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  • 1.
    Audehm, Uwe
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Trube, Anke
    Institute of Zoophysiology, University of Bonn, Germany.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Patterns and projections of crustacean cardioactive-peptide-immunoreactive neurons of the terminal ganglion of crayfish.1993In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 272, no 3, p. 473-485Article in journal (Refereed)
    Abstract [en]

    Three distinct clusters of crustacean cardioactive-peptide-immunoreactive neurones occur in the terminal abdominal ganglion of the crayfish species Orconectes limosus, Astacus leptodactylus, Astacus astacus and Procambarus clarkii, as revealed by immunocytochemistry of whole-mount preparations and sections. They exhibit similar topology and projection patterns in all four studied species. An anterior ventral lateral and a posterior lateral cluster contain one small, strongly stained perikaryon and two large, less intensely stained perikarya, each showing contralateral projections. A posterior medial lateral cluster of up to six cells also contains these two types of perikarya. Whereas the small type perikarya belong to putative interneurones, the large type perikarya give rise to extensive neurohaemal plexuses in perineural sheaths of the third roots of the fifth abdominal ganglia, the connectives, the dorsal telson nerves, the ganglion itself, its roots and arteriolar supply. Thin fibres from these plexuses reach newly discovered putative neurohaemal areas around the hindgut and anus via the intestinal and the anal nerves, and directly innervate the phasic telson musculature. A comparison with earlier investigations of motoneurones and segmentation indicates that these three cell groups containing putative neurosecretory neurones may be members of at least three neuromeres in this ganglion. Crustacean cardioactive peptide released from these neurones may participate in the neurohumoral and modulatory control of different neuronal and muscle targets, thereby exceeding its previously established hindgut and heart excitatory effects.

  • 2. Breidbach, O
    et al.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Wegerhoff, R
    Common general morphological pattern of peptidergic neurons in the arachnid brain: crustacean cardioactive peptide-immunoreactive neurons in the protocerebrum of seven arachnid species.1995In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 279, no 1, p. 183-197Article in journal (Refereed)
    Abstract [en]

    A polyclonal antiserum raised against crustacean cardioactive peptide labels 14 clusters of immunoreactive neurons in the protocerebrum of the spiders Tegenaria atrica and Nephila clavipes, and the harvestman (opilionid) Rilaena triangularis. In all species, these clusters possess the same number of neurons, and share similar structural and topological characteristics. Two sets of bilateral symmetrical neurons associated with the optic lobes and the arachnid "central body" were analysed in detail, comparing the harvestman R. triangularis and the spiders Brachypelma albopilosa (Theraphosidae), Cupiennius salei (Lycosidae), Tegenaria atrica (Agelenidae), Meta segmentata (Metidae) and Nephila clavipes (Araneidae). Sixteen neurons have been identified that display markedly similar axonal pathways and arborization patterns in all species. These neurons are considered homologues in the opilionid and the araneid brains. We presume that these putative phylogenetically persisting neurons represent part of the general morphological pattern of the arachnid brain.

  • 3. Breidbach, Olaf
    et al.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Crustacean cardioactive peptide-immunoreactive neurons in the ventral nerve cord and the brain of the meal beetle Tenebrio molitor during postembryonic development1991In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 265, no 1, p. 129-144Article in journal (Refereed)
    Abstract [en]

    By use of an antiserum against the crustacean cardioactive peptide (CCAP) several types of bilaterally symmetrical neurons were mapped quantitatively in the ventral nerve cord and brain of Tenebrio molitor. The general architecture of these neurons was reconstructed. From the suboesophageal to the 7th abdominal ganglia 2 types of neurons showed a repetitive organization of contralateral projection patterns in each neuromere. The first type had few branches in the central neuropil and a distinct peripheral projection. The 2nd type was characterized by an elaborate central branching pattern, which included ascending and descending processes. Some of its peripheral branches supplied peripheral neurohaemal areas. In the protocerebrum, 10 CCAP-immunoreactive neurons occurred with projections into the superior median protocerebrum and the tritocerebrum. Immunopositive neurons were mapped in larvae, pupae and adults. All types of identified neurons persisted throughout metamorphosis, maintaining their essential structural and topological characteristics. The CCAP-immunoreactive neurons of T. molitor were compared with those described for Locusta migratoria. Putative structural homologies of subsets of neurons in both species are discussed.

  • 4.
    Breidbach, Olaf
    et al.
    Institute of Applied Zoology, University of Bonn, Germany.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Proctolin-immunoreactive neurons persist during metamorphosis of an insect: A developmental study of the ventral nerve cord of Tenebrio molitor(Coleoptera)1989In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 257, no 1, p. 217-225Article in journal (Refereed)
    Abstract [en]

    Proctolin-immunoreactive neurons in all neuromers of the ventral nerve cord of Tenebrio molitor L. have been quantitatively demonstrated and mapped throughout metamorphosis. Each neuromer contains an anterior and a posterior group of neurons with light and dark staining properties as revealed by peroxidase-antiperoxidase labeling. Serial homologous subsets of dark staining neurons with central and peripheral projections have been identified and found to persist during morphogenetic changes from the larva to the adult. Most neurons maintain their topological and structural characteristics throughout metamorphosis. The identified proctolin-immunoreactive neurons exhibit structures similar to those described in other insect species; some may correspond known motoneurons.

  • 5.
    Brooke-Jones, Megan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gáliková, Martina
    Stockholm University, Faculty of Science, Department of Zoology.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Cyanobacterial Neurotoxin Beta-Methyl-Amino-l-Alanine Affects Dopaminergic Neurons in Optic Ganglia and Brain of Daphnia magna2018In: Toxins, ISSN 2072-6651, E-ISSN 2072-6651, Vol. 10, no 12, article id 527Article in journal (Refereed)
    Abstract [en]

    The non-proteinogenic amino acid beta-methyl-amino-l-alanine (BMAA) is a neurotoxin produced by cyanobacteria. BMAA accumulation in the brain of animals via biomagnification along the food web can contribute to the development of neurodegenerative diseases such as Amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC), the latter being associated with a loss of dopaminergic neurons. Daphnia magna is an important microcrustacean zooplankton species that plays a key role in aquatic food webs, and BMAA-producing cyanobacteria often form part of their diet. Here, we tested the effects of BMAA on putative neurodegeneration of newly identified specific dopaminergic neurons in the optic ganglia/brain complex of D. magna using quantitative tyrosine-hydroxylase immunohistochemistry and fluorescence cytometry. The dopaminergic system was analysed in fed and starved isogenic D. magna adults incubated under different BMAA concentrations over 4 days. Increased BMAA concentration showed significant decrease in the stainability of dopaminergic neurons of D. magna, with fed animals showing a more extreme loss. Furthermore, higher BMAA concentrations tended to increase offspring mortality during incubation. These results are indicative of ingested BMAA causing neurodegeneration of dopaminergic neurons in D. magna and adversely affecting reproduction. This may imply similar effects of BMAA on known human neurodegenerative diseases involving dopaminergic neurons.

  • 6. Bungart, D
    et al.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Keller, R
    Quantitative determination and distribution of the myotropic neuropeptide orcokinin in the nervous system of astacidean crustaceans.1994In: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 15, no 3, p. 393-400Article in journal (Refereed)
    Abstract [en]

    For quantitative determinations of orcokinin, an indirect, noncompetitive sandwich ELISA was developed. This ELISA is highly specific for orcokinin and the detection limit is 1 fmol. In three astacidean species (Orconectes limosus, Homarus americanus, and Astacus astacus) orcokinin immunoreactivity (OK-IR) was measurable in all parts of the nervous system. Upon normalization to the protein content of the tissue (pmol/mg protein), concentrations were shown to be in the same range in all three species. The distribution of OK-IR in the nervous system is also very similar in the three species. In Orconectes limosus the following values were obtained (in pmol/mg protein): cerebral ganglion 215, optic ganglia in the eyestalk 38, subesophageal ganglion 182. The thoracic ganglia have lower concentrations (35-72) and the abdominal ganglia (AG) 1-5 even lower ones (11-17). In the AG 6 of Orconectes, from which the innervation of the hindgut arises, concentrations are approximately five times higher than in the other AG. In hindgut tissue, relatively high concentrations of 22 pmol/mg were measured, which is in agreement with the demonstrated function of orcokinin as a hindgut excitatory substance. Markedly elevated levels of orcokinin were observed in the AG 6 of Astacus, but not in Homarus. Orcokinin could also be measured consistently and reliably in the hemolymph, where its concentration is approximately 1 x 10(-11) M. These results show that orcokinin may be released into the hemolymph and may act as a hormone, in addition to its role as a locally acting neurotransmitter/modulator.

  • 7. Bungart, D
    et al.
    Hilbich, C
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Keller, R
    Occurrence of analogues of the myotropic neuropeptide orcokinin in the shore crab, Carcinus maenas: evidence for a novel neuropeptide family.1995In: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 16, no 1, p. 67-72Article in journal (Refereed)
    Abstract [en]

    By use of an enzyme immunoassay that was developed for the determination of orcokinin, a myotropic neuropeptide of the sequence NFDEIDRSGFGFN from the crayfish, Orconectes limosus, immunoreactive material was detected in extracts of thoracic ganglia from the shore crab, Carcinus maenas. Isolation of the immunoreactive material was achieved by the following steps: 1) prepurification by gel filtration, 2) immunoaffinity chromatography on an anti-orcokinin IgG protein-A sepharose column, and 3) reversed-phase HPLC. The HPLC profile after affinity purification revealed three main immunoreactive peptides that were rechromatographed. None of these peptides was identical to orcokinin in terms of retention time. Automated gas-phase sequencing revealed these peptides to be analogues of orcokinin differing in one amino acid residue. They were named [Ser9]-, [Ala13]- and [Val13]orcokinin (NFDEIDRSSFGFN, Mr 1549.3; NFDEIDRSGFGFA, Mr 1475.3; NFDEIDRSGFGFV, Mr 1503.9). Carboxypeptidase A treatment of the peptides indicated a free C-terminus. Complete characterization of the three peptides was achieved from approximately 230 thoracic ganglia of Carcinus maenas.

  • 8.
    Böcking, Detlef
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Keller, Rainer
    Institute of Zoophysiology, University of Bonn, Germany.
    The crustacean neuropeptides of the CHH/MIH/GIH family: Structures and biological activities.2002In: The Crustacean Nervous System. / [ed] Konrad Wiese, Heidelberg: Springer , 2002, p. 84-97Chapter in book (Other academic)
  • 9. Campos, Bruno
    et al.
    Rivetti, Claudia
    Kress, Timm
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Barata, Carlos
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Depressing antidepressant: Fluoxetine affects serotonin neurons causing adverse reproductive responses in Daphnia magna2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 11, p. 6000-6007Article in journal (Refereed)
    Abstract [en]

    Selective serotonin reuptake inhibitors (SSRIs) are widely used antidepressants. As endocrine disruptive contaminants in the environment, SSRIs affect reproduction in aquatic organisms. In the water flea Daphnia magna, SSRIs increase offspring production in a food ration-dependent manner. At limiting food conditions, females exposed to SSRIs produce more but smaller offspring, which is a maladaptive life-history strategy. We asked whether increased serotonin levels in newly identified serotonin-neurons in the Daphnia brain mediate these effects. We provide strong evidence that exogenous SSRI fluoxetine selectively increases serotonin-immunoreactivity in identified brain neurons under limiting food conditions thereby leading to maladaptive offspring production. Fluoxetine increases serotonin-immunoreactivity at low food conditions to similar maximal levels as observed under high food conditions and concomitantly enhances offspring production. Sublethal amounts of the neurotoxin 5,7-dihydroxytryptamine known to specifically ablate serotonin-neurons markedly decrease serotonin-immunoreactivity and offspring production, strongly supporting the effect to be serotonin-specific by reversing the reproductive phenotype attained under fluoxetine. Thus, SSRIs impair serotonin-regulation of reproductive investment in a planktonic key organism causing inappropriately increased reproduction with potentially severe ecological impact.

  • 10. Chung, J S
    et al.
    Dircksen, Henrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Webster, S G
    A remarkable, precisely timed release of hyperglycemic hormone from endocrine cells in the gut is associated with ecdysis in the crab Carcinus maenas1999In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 96, no 23, p. 13103-7Article in journal (Refereed)
    Abstract [en]

    Molting or ecdysis is the most fundamentally important process in arthropod life history, because shedding of the exoskeleton is an absolute prerequisite for growth and metamorphosis. Although the hormonal mechanisms driving ecdysis in insects have been studied extensively, nothing is known about these processes in crustaceans. During late premolt and during ecdysis in the crab Carcinus maenas, we observed a precise and reproducible surge in hemolymph hyperglycemic hormone (CHH) levels, which was over 100-fold greater than levels seen in intermolt animals. The source of this hormone surge was not from the eyestalk neurosecretory tissues but from previously undescribed endocrine cells (paraneurons), in defined areas of the foregut and hindgut. During premolt (the only time when CHH is expressed by these tissues), the gut is the largest endocrine tissue in the crab. The CHH surge, which is a result of an unusual, almost complete discharge of the contents of the gut endocrine cell, regulates water and ion uptake during molting, thus allowing the swelling necessary for successful ecdysis and the subsequent increase in size during postmolt. This study defines an endocrine brain/gut axis in the arthropods. We propose that the ionoregulatory process controlled by CHH may be common to arthropods, in that, for insects, a similar mechanism seems to be involved in antidiuresis. It also seems likely that a cascade of very precisely coordinated release of (neuro) hormones controls ecdysis.

  • 11.
    Chung, J S
    et al.
    Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA.
    Wilcockson, D C
    Zmora, N
    Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA.
    Zohar, Y
    Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA.
    Dircksen, H
    Stockholm University, Faculty of Science, Department of Zoology.
    Webster, S G
    Identification and developmental expression of mRNAs encoding crustacean cardioactive peptide (CCAP) in decapod crustaceans.2006In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 209, no Pt 19, p. 3862-72Article in journal (Refereed)
    Abstract [en]

    Full-length cDNAs encoding crustacean cardioactive peptide (CCAP) were isolated from several decapod (brachyuran and astacuran) crustaceans: the blue crab Callinectes sapidus, green shore crab Carcinus maenas, European lobster Homarus gamarus and calico crayfish Orconectes immunis. The cDNAs encode open reading frames of 143 (brachyurans) and 139-140 (astacurans) amino acids. Apart from the predicted signal peptides (30-32 amino acids), the conceptually translated precursor codes for a single copy of CCAP and four other peptides that are extremely similar in terms of amino acid sequence within these species, but which clearly show divergence into brachyuran and astacuran groups. Expression patterns of CCAP mRNA and peptide were determined during embryonic development in Carcinus using quantitative RT-PCR and immunohistochemistry with whole-mount confocal microscopy, and showed that significant mRNA expression (at 50% embryonic development) preceded detectable levels of CCAP in the developing central nervous system (CNS; at 70% development). Subsequent CCAP gene expression dramatically increased during the late stages of embryogenesis (80-100%), coincident with developing immunopositive structures. In adult crabs, CCAP gene expression was detected exclusively in the eyestalk, brain and in particular the thoracic ganglia, in accord with the predominance of CCAP-containing cells in this tissue. Measurement of expression patterns of CCAP mRNA in Carcinus and Callinectes thoracic ganglia throughout the moult cycle revealed only modest changes, indicating that previously observed increases in CCAP peptide levels during premoult were not transcriptionally coupled. Severe hypoxic conditions resulted in rapid downregulation of CCAP transcription in the eyestalk, but not the thoracic ganglia in Callinectes, and thermal challenge did not change CCAP mRNA levels. These results offer the first tantalising glimpses of involvement of CCAP in environmental adaptation to extreme, yet biologically relevant stressors, and perhaps suggest that the CCAP-containing neurones in the eyestalk might be involved in adaptation to environmental stressors.

  • 12. Chung, J. Sook
    et al.
    Katayama, Hidekazu
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    New Functions of Arthropod Bursicon: Inducing Deposition and Thickening of New Cuticle and Hemocyte Granulation in the Blue Crab, Callinectes sapidus2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 9, p. e46299-Article in journal (Refereed)
    Abstract [en]

    Arthropod growth requires molt-associated changes in softness and stiffness of the cuticle that protects from desiccation, infection and injury. Cuticle hardening in insects depends on the blood-borne hormone, bursicon (Burs), although it has never been determined in hemolymph. Whilst also having Burs, decapod crustaceans reiterate molting many more times during their longer life span and are encased in a calcified exoskeleton, which after molting undergoes similar initial cuticle hardening processes as in insects. We investigated the role of homologous crustacean Burs in cuticular changes and growth in the blue crab, Callinectes sapidus. We found dramatic increases in size and number of Burs cells during development in paired thoracic ganglion complex (TGC) neurons with pericardial organs (POs) as neurohemal release sites. A skewed expression of Burs β/Burs α mRNA in TGC corresponds to protein contents of identified Burs β homodimer and Burs heterodimer in POs. In hemolymph, Burs is consistently present at ~21 pM throughout the molt cycle, showing a peak of ~89 pM at ecdysis. Since initial cuticle hardness determines the degree of molt-associated somatic increment (MSI), we applied recombinant Burs in vitro to cuticle explants of late premolt or early ecdysis. Burs stimulates cuticle thickening and granulation of hemocytes. These findings demonstrate novel cuticle-associated functions of Burs during molting, while the unambiguous and constant presence of Burs in cells and hemolymph throughout the molt cycle and life stages may implicate further functions of its homo- and heterodimer hormone isoforms in immunoprotective defense systems of arthropods.

  • 13. Davis, N T
    et al.
    Homberg, U
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Levine, R B
    Hildebrand, J G
    Crustacean cardioactive peptide-immunoreactive neurons in the hawkmoth Manduca sexta and changes in their immunoreactivity during postembryonic development.1993In: Journal of Comparative Neurology, ISSN 0021-9967, E-ISSN 1096-9861, Vol. 338, no 4, p. 612-27Article in journal (Refereed)
    Abstract [en]

    An antiserum against crustacean cardioactive peptide was used, in indirect immunocytochemistry on whole-mounts and Vibratome sections, to map immunoreactive neurons at various stages of postembryonic development of the hawkmoth Manduca sexta. About 90 immunoreactive neurons were identified. Many of these cells are immunoreactive at hatching and persist into the adult stage; others become immunoreactive late in postembryonic development. During adult development, transient immunoreactivity is expressed in several cells in the subesophageal and thoracic ganglia. Two sets of immunoreactive neurons are found in the protocerebrum of larvae, but only one of these sets persists into the adult stage. Paired lateral interneurons and neurosecretory neurons are segmentally repeated in the abdominal ganglia and are present from the first larval stage to the adult; the abdominal interneurons project contralaterally to arborizations in adjacent ganglia, and some ascend to tritocerebral arborizations. The abdominal neurosecretory cells, which correspond to a pair of cells reported to contain bursicon, project posteriorly to neurohemal release organs. Motor neurons of dorsal external oblique abdominal muscles become immunoreactive in the fourth larval stage. Paired median neurosecretory cells of abdominal ganglia become immunoreactive during the fifth larval stage. The immunoreactive median and lateral abdominal neurosecretory cells are a subset of a group of cells known to contain cardioactive peptides. Paired lateral neurosecretory cells of the subesophageal ganglion become immunoreactive during pupation and project to the corpora cardiaca and aorta of the adult. Many of the neurons identified here are comparable to crustacean cardioactive peptide-immunoreactive cells described previously in locusts and the mealworm beetle.

  • 14. Derst, Christian
    et al.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Meusemann, Karen
    Zhou, Xin
    Liu, Shanlin
    Predel, Reinhard
    Evolution of neuropeptides in non-pterygote hexapods2016In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 16, article id 51Article in journal (Refereed)
    Abstract [en]

    Background

    Neuropeptides are key players in information transfer and act as important regulators of development, growth, metabolism, and reproduction within multi-cellular animal organisms (Metazoa). These short protein-like substances show a high degree of structural variability and are recognized as the most diverse group of messenger molecules. We used transcriptome sequences from the 1KITE (1K Insect Transcriptome Evolution) project to search for neuropeptide coding sequences in 24 species from the non-pterygote hexapod lineages Protura (coneheads), Collembola (springtails), Diplura (two-pronged bristletails), Archaeognatha (jumping bristletails), and Zygentoma (silverfish and firebrats), which are often referred to as “basal” hexapods. Phylogenetically, Protura, Collembola, Diplura, and Archaeognatha are currently placed between Remipedia and Pterygota (winged insects); Zygentoma is the sistergroup of Pterygota. The Remipedia are assumed to be among the closest relatives of all hexapods and belong to the crustaceans.

    Results

    We identified neuropeptide precursor sequences within whole-body transcriptome data from these five hexapod groups and complemented this dataset with homologous sequences from three crustaceans (including Daphnia pulex), three myriapods, and the fruit fly Drosophila melanogaster. Our results indicate that the reported loss of several neuropeptide genes in a number of winged insects, particularly holometabolous insects, is a trend that has occurred within Pterygota. The neuropeptide precursor sequences of the non-pterygote hexapods show numerous amino acid substitutions, gene duplications, variants following alternative splicing, and numbers of paracopies. Nevertheless, most of these features fall within the range of variation known from pterygote insects. However, the capa/pyrokinin genes of non-pterygote hexapods provide an interesting example of rapid evolution, including duplication of a neuropeptide gene encoding different ligands.

    Conclusions

    Our findings delineate a basic pattern of neuropeptide sequences that existed before lineage-specific developments occurred during the evolution of pterygote insects.

  • 15.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Conserved crustacean cardioactive peptide neural networks and functions in arthropod evolution1998In: Recent Advances in Arthropod Endocrinology / [ed] Geoffrey M. Coast, Simon G. Webster, Cambridge: Cambridge University Press, 1998, 65, p. 302-333Chapter in book (Refereed)
  • 16.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Crustacean bioactive peptides2013In: Handbook of Biologically Active Peptides / [ed] Abba J. Kastin, New York: Academic Press Elsevier , 2013, 2, p. 209-221Chapter in book (Refereed)
    Abstract [en]

    Research on crustacean peptides has concentrated mainly on decapods and isopods, and a growing number of >200 peptides have been sequenced from these two groups, the majority from decapods, but recently, the annotation of the Daphnia pulexgenome has contributed many more novel peptides many of which were also sequenced de novo. Identified and bioactive crustacean peptides — the only ones reported here — regulate a large range of physiological functions, including color change, activities of heart, exoskeletal and visceral muscles, metabolic function, development, metamorphosis, and reproduction.

  • 17.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Distribution and physiology of crustacean cardioactive peptide in arthropods1994In: Perspectives in Comparative Endocrinology / [ed] Davey, K. G. Peter, R. E. Tobe, S. S., Ottawa: Natl Research Council Canada , 1994, p. 139-148Chapter in book (Other academic)
  • 18.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Fine structure of the neurohemal sinus gland of the shore crab, Carcinus maenas, and immuno-electron-microscopic identification of neurosecretory endings according to their neuropeptide contents1992In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 269, no 2, p. 249-266Article in journal (Refereed)
    Abstract [en]

    The sinus gland of the shore crab, Carcinus maenas, is a compact assembly of interdigitating neurosecretory axon endings abutting upon the thin basal lamina of a central hemolymph lacuna. Four types of axon endings are distinguishable by the size distribution, shape, electron density and core structure of their neurosecretory granules. One additional type of axon ending is characterized by electron-lucent vacuoles and vesicles. The axon profiles are surrounded by astrocyte-like glial cells. Various fixations followed by epoxy- or Lowicryl-embedding were compared in order to optimize the preservation of the fine structure of the granule types and the antigenicity of their peptide hormone contents. By use of specific rabbit antisera, the crustacean hyperglycemic, molt-inhibiting, pigment-dispersing, and red-pigment-concentrating hormones were assigned to the four distinct granule types which showed no overlap of immunostaining. Epi-polarization microscopy and ultrathin section analysis of immunogold-stained Lowicryl-embedded specimens revealed that immunoreactivity to Leu-enkephalin and proctolin is co-localized with molt-inhibiting hormone immunoreactivity in the same type of granule. The size and core structure of the immunocytochemically identified granule types vary little with the different pretreatments but, in some cases, to a statistically significant extent. The present results are compared with those from earlier studies of sinus glands in different crustaceans. The methods of granule identification used in this study supplement the classical approach in granule typing; they are easier to perform and more reliable for the analysis of release phenomena in identified secretory neurons supplying the neurohemal sinus gland.

  • 19.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Immunocytochemical identification of the neurosecretory products of the pericardial organs of Carcinus maenas1990In: Frontiers in crustacean neurobiology / [ed] K. Wiese, W.D. Krenz , J. Tautz, H. Reichert, B. Mulloney, Basel, Boston, Berlin: Birkhäuser , 1990, p. 487-491Chapter in book (Other academic)
  • 20.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Department of Functional Morphology.
    Insect ion transport peptides are derived from alternatively spliced genes and differentially expressed in the central and peripheral nervous system.2009In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 212, no Pt 3, p. 401-12Article in journal (Refereed)
    Abstract [en]

    Insect ionic and fluid homeostasis relies upon the Malpighian tubules (MT) and different hindgut compartments. Primary urine formed in MTs is finally modified by ion, solute and water reabsorptive processes primarily in the hindgut under the control of several large peptide hormones. One of these, the ion transport peptide (ITP), is a chloride transport-stimulating and acid secretion-inhibiting hormone similar to crustacean hyperglycaemic hormones (CHHs). In locusts, moths and fruit flies, ITP together with the slightly longer ITPL isoforms, inactive in hindgut bioassays, arise by alternative splicing from very similar itp genes. ITP and ITPL are differentially distributed in (1) pars lateralis/retrocerebral complex neurosecretory cells (NSCs) containing both splice forms, (2) interneurons with either one of the splice forms, (3) hindgut-innervating abdominal ITP neurons (in Drosophila only), and (4) intrinsic, putative sensory NSCs in peripheral neurohaemal perisympathetic/perivisceral organs or transverse nerves (usually containing ITPL). Both splice forms occur as hormones released into the haemolymph in response to feeding or stress stimuli. ITPL mainly released from the peripheral NSCs is discussed as a competitive inhibitor (as established in vitro) of ITP action on yet to be identified hindgut ITP receptors. Furthermore, some evidence has been provided for possible ecdysis-related functions of ITP and/or ITPL in moths. The comparative data on the highly similar gene, precursor and primary structures and similar differential distributions in insect and crustacean NSCs suggest that CHH/ITP and ITPL neuropeptide-producing cells and their gene products share common phylogenetic ancestry.

  • 21.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Myoactive and neuroactive peptides in crustaceans2002In: Proceedings of the 21st Conference of European Comparative Endocrinologists / [ed] Keller, R. Dircksen, H. Sedlmeier, D. Vaudry, H., Bologna: Medimond S R L , 2002, p. 367-373Chapter in book (Other academic)
    Abstract [en]

    Bioassays of visceral muscles in decapod crustaceans have been used to identify bioactive peptides from neurohaemal pericardial organs (POs) or nervous systems. PO-peptides such as proctolin, FLRFa-related peptides (FaRPs) and CCAP affect heart beat and ventilatory activity, and using hindgut bioassays (even insect hindguts) helped to discover further myoactive FaRPs, orcokinins, orcomyotropin and members, e.g., of tachykinin, myokinin, sulfakinin and allatostatin peptide families. Immunocytochemistry revealed wide distributions of the peptides in neurosecretory neurones and interneurones of the CNS and peripheral nervous systems indicative of several neuronal activities, some of which have been established on e.g. stomatogastric ganglion (STG) or nerve-(skeletal) muscle preparations.

  • 22.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Neurosecretory endings in the pericardial organs of the shore crab Carcinus maenas L., and their identification by neuropeptide immunocytochemistry1991In: Comparative aspects of neuropeptide function. / [ed] Ernst Florey, George B. Stefano, Manchester, New York: Manchester University Press, 1991, p. 198-200Chapter in book (Other academic)
  • 23.
    Dircksen, Heinrich
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Burdzik, S.
    Sauter, A.
    Keller, R.
    Two orcokinins and the novel octapeptide orcomyotropin in the hindgut of the crayfish Orconectes limosus: identified myostimulatory neuropeptides originating together in neurones of the terminal abdominal ganglion2000In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 203, no 18, p. 2807-2818Article in journal (Refereed)
    Abstract [en]

    The tridecapeptides Asn(13)-orcokinin and Val(13)-orcokinin, two known members of the orcokinin neuropeptide family native to crustaceans, and a novel octapeptide, orcomyotropin, FDAFTTGFamide, have been identified from extracts of hindguts of the crayfish Orconectes limosus using an isolated hindgut contractility bioassay, high-performance liquid chromatography, microsequencing and mass spectrometry. All three peptides display strong inotropic actions on crayfish hindguts. Orcomyotropin showed higher potency than the two orcokinins. Threshold concentration was approximately 5 x 10(-12)mol l(-1)versus 10(-10)mol l(-1) for the two orcokinins. An approximately fivefold increase in contraction amplitude was observed with 10(-9)mol l(-1) orcomyotropin and 10(-7)mol l(-1) of the orcokinins. Asn(13)- and Val(13)-orcokinin did not differ significantly with regard to their biological effects. Semi-isolated crayfish hearts and locust oviducts did not respond to the three peptides. Immunocytochemistry using antisera against Asn(13)-orcokinin and orcomyotropin showed that these neuropeptides are co-localized in approximately 80-90 neurones of the terminal abdominal ganglion that have been shown to innervate the entire hindgut muscularis via the intestinal nerve. The neurones form elaborate terminal branches preferentially on longitudinal hindgut muscles. Orcomyotropin is a novel crustacean member of the GF-amide family of myotropic and/or allatotropic neuropeptides from annelids, molluscs and insects.

  • 24.
    Dircksen, Heinrich
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Böcking, D
    Heyn, U
    Mandel, C
    Chung, J S
    Baggerman, G
    Verhaert, P
    Daufeldt, S
    Plösch, T
    Jaros, P P
    Waelkens, E
    Keller, R
    Webster, S G
    Crustacean hyperglycaemic hormone (CHH)-like peptides and CHH-precursor-related peptides from pericardial organ neurosecretory cells in the shore crab, Carcinus maenas, are putatively spliced and modified products of multiple genes.2001In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 356, no Pt 1, p. 159-70Article in journal (Refereed)
    Abstract [en]

    About 24 intrinsic neurosecretory neurons within the pericardial organs (POs) of the crab Carcinus maenas produce a novel crustacean hyperglycaemic hormone (CHH)-like peptide (PO-CHH) and two CHH-precursor-related peptides (PO-CPRP I and II) as identified immunochemically and by peptide chemistry. Edman sequencing and MS revealed PO-CHH as a 73 amino acid peptide (8630 Da) with a free C-terminus. PO-CHH and sinus gland CHH (SG-CHH) share an identical N-terminal sequence, positions 1-40, but the remaining sequence, positions 41-73 or 41-72, differs considerably. PO-CHH may have different precursors, as cDNA cloning of PO-derived mRNAs has revealed several similar forms, one exactly encoding the peptide. All PO-CHH cDNAs contain a nucleotide stretch coding for the SG-CHH(41-76) sequence in the 3'-untranslated region (UTR). Cloning of crab testis genomic DNA revealed at least four CHH genes, the structure of which suggest that PO-CHH and SG-CHH arise by alternative splicing of precursors and possibly post-transcriptional modification of PO-CHH. The genes encode four exons, separated by three variable introns, encoding part of a signal peptide (exon I), the remaining signal peptide residues, a CPRP, the PO-CHH(1-40)/SG-CHH(1-40) sequences (exon II), the remaining PO-CHH residues (exon III) and the remaining SG-CHH residues and a 3'-UTR (exon IV). Precursor and gene structures are more closely related to those encoding related insect ion-transport peptides than to penaeid shrimp CHH genes. PO-CHH neither exhibits hyperglycaemic activity in vivo, nor does it inhibit Y-organ ecdysteroid synthesis in vitro. From the morphology of the neurons it seems likely that novel functions remain to be discovered.

  • 25.
    Dircksen, Heinrich
    et al.
    University of Bonn, Germany.
    Heyn, Uwe
    Crustacean hyperglycemic hormone-like peptides in crab and locust peripheral intrinsic neurosecretory cells1998In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 839, p. 392-394Article in journal (Refereed)
  • 26.
    Dircksen, Heinrich
    et al.
    Rheinische Friedrich-Wilhelms-Universität, Germany.
    Homberg, Uwe
    Crustacean Cardioactive Peptide-immunoreactive neurons innervating brain neuropils, retrocerebral complex and stomatogastric nervous-system of the locust, Locusta migratoria1995In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 279, p. 495-515Article in journal (Refereed)
    Abstract [en]

    The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.

  • 27.
    Dircksen, Heinrich
    et al.
    Rheinische Friedrich-Wilhelms Universität, Germany.
    Keller, Rainer
    Immunocytochemical localization of CCAP, a novel crustacean cardioactive peptide, in the nervous system of the shore crab, Carcinus maenas L.1988In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 254, no 2, p. 347-360Article in journal (Refereed)
    Abstract [en]

    Polyclonal antibodies were raised in rabbits against synthetic crustacean cardioactive peptide (CCAP) conjugated to bovine thyroglobulin, and were used to map CCAP-immunoreactive structures in the central nervous system of Carcinus maenas. As expected, the neurohemal pericardial organs (PO) displayed abundant immunoreactivity in nerve fibers and terminals. In addition, immunoreactive neurons were demonstrated in other parts of the nervous system. At least some of them do not appear to terminate in neurohemal structures and may have a non-endocrine, as yet unknown function. Immunoreactive perikarya with a diameter of 25–30 m occur in the brain. They project into the optic and antennary neuropil, and into the eyestalk. One cell was found in the medulla terminalis of the eyestalk and in the connective ganglion, respectively. From the latter, axonal branches could be traced into the brain and the thoracic ganglia (TG). In the TG, small-diameter perikarya give rise to extensive networks of varicose fibers. Some of the perikarya occur in a characteristic paired arrangement with larger CCAP-immunoreactive somata (diameter 40–50 m). These pairs of one small and one large cell occur in all mouthpart and leg segments of the TG, except the abdominal ganglia (AG), where only large cells were found. The main projections of the large neurons comprise one or more fibers in each of the seven segmental nerves (SN), leading to neurosecretory terminals in the PO. The fibers in the SN are joined by branches of an ascending axonal tract from the large perikarya in the AG. The large-type perikarya are considered to be the principal source of CCAP in the PO. The optic ganglia in the eyestalk, except the medulla terminalis, the neurohemal sinus gland and the stomatogastric nervous system are devoid of CCAP-immunoreactivity.In axon terminals of the PO, CCAP is not colocalized with other PO-neuropeptides, i.e. proctolin-, FMRFamide-like, and Leu-enkephalin-like immunoreactive materials. Electron-microscopic immunocytochemistry revealed a distinct CCAP-containing granule type in specific axon profiles and terminals in the PO.The architecture of CCAP-immunoreactive neurons is discussed with respect to previous morphological studies on the origin and pathways of fibers terminating in the PO.

  • 28.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Stockholm University, Faculty of Science, Department of Zoology.
    Mandali, Aditya
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Stockholm University, Faculty of Science, Department of Zoology.
    Yoshii, Taishi
    Strauss, Johannes
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Stockholm University, Faculty of Science, Department of Zoology.
    Helfrich-Foerster, Charlotte
    Nässel, Dick R
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Stockholm University, Faculty of Science, Department of Zoology.
    Differential neuronal expression of three Drosophila ion transport peptide splice forms indicate multiple functions of peptidergic neurons2009In: Comparative Biochemistry and Physiology A, ISSN 1095-6433, E-ISSN 1531-4332, Vol. 153A, no 2, suppl. 1, p. S79-Article in journal (Refereed)
    Abstract [en]

    We identified previously two long (DrmITPL1 and -L2) and one amidated short isoform (DrmITP) of insect ion transport peptides (ITPs) as products derived by alternatively splicing from the Drosophila itp-gene (CG13586). The peptides are members of a large family of arthropod neuropeptides incl. crustacean hyperglycemic hormones (CHH/ITP-family), but similar ITPs are only known in locusts to have antidiuretic bioactivity on the hindgut. We localised the peptides by in situ hybridisation and immunocytochemistry with isoform-specific antibodies in the nervous system of larval (L3) and adult Drosophila melanogaster and screened Gal4-lines specific for peptidergic cells. Four neurosecretory cells in brain-corpora cardiaca/allata putatively release DrmITP as a hormone in all stages. DrmITP also occurs in interneurons in the brain/ventral ganglia and in neurons efferent towards the hindgut. Some interneurons are identical to well-known circadian clock neurons for which the effector molecules were elusive but are responsible for the evening bouts of locomotor activity in flies. DrmITPL1 and -L2 were found only in peripheral lateral bipolar and putative sensory neurons which are likely to play a role in the control of growth, hindgut ion transport and heart beat. With DrmITP identified in brain neurosecretory cells, hindgut-innervating neurons in the abdominal ganglia and one pair in the abdomen close to the larval anal organ or innervating the adult rectal pads, both chloride-transporting organs, we are facing an enormous complexity in multiple functions of differentially expressed ITP/Ls derived from a single gene. Preliminary results using Gal4-driven RNAi in distinct peptidergic neurons look promising to find deficiency phenotypes.

  • 29.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Müller, Arno
    Keller, Rainer
    Crustacean cardioactive peptide in the nervous system of the locust, Locusta migratoria: an immunocytochemical study on the ventral nerve cord and peripheral innervation1991In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 263, p. 439-457Article in journal (Refereed)
    Abstract [en]

    Crustacean cardioactive peptide-immunoreactive neurons occur in the entire central nervous system of Locusta migratoria. The present paper focuses on mapping studies in the ventral nerve cord and on peripheral projection sites. Two types of contralaterally projecting neurons occur in all neuromers from the subesophageal to the seventh abdominal ganglia. One type forms terminals at the surface of the thoracic nerves 6 and 1, the distal perisympathetic organs, the lateral heart nerves, and on ventral and dorsal diaphragm muscles. Two large neurons in the anterior part and several neurons of a different type in the posterior part of the terminal ganglion project into the last tergal nerves. In the abdominal neuromers 1–7, two types of ipsilaterally projecting neurons occur, one of which gives rise to neurosecretory terminals in the distal perisympathetic organs, in peripheral areas of the transverse, stigmata and lateral heart nerves. Four subesophageal neurons have putative terminals in the neurilemma of the nervus corporis allati II, and in the corpora allata and cardiaca. In addition, several immunoreactive putative interneurons and other neurons were mapped in the ventral nerve cord. A new in situ whole-mount technique was essential for elucidation of the peripheral pathways and targets of the identified neurons, which suggest a role of the peptide in the control of heartbeat, abdominal ventilatory and visceral muscle activity.

  • 30.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Neupert, Susanne
    Predel, Reinhard
    Verleyen, Peter
    Huybrechts, Jurgen
    Strauss, Johannes
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Hauser, Frank
    Stafflinger, Elisabeth
    Schneider, Martina
    Pauwels, Kevin
    Schoofs, Liliane
    Grimmelikhuijzen, Cornelis J. P.
    Genomics, transcriptomics and peptidomics of Daphnia pulex neuropeptides and protein hormones2011In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 10, no 10, p. 4478-4504Article in journal (Refereed)
    Abstract [en]

    We report 43 novel genes in the water flea Daphnia pulex encoding 73 predicted neuropeptide and protein hormones as partly confirmed by RT-PCR. MALDI-TOF mass spectrometry identified 40 neuropeptides by mass matches and 30 neuropeptides by fragmentation sequencing. Single genes encode adipokinetic hormone, allatostatin-A, allatostatin-B, a first crustacean allatotropin, Ala7-CCAP, one CCHamide, Arg7-corazonin, CRF-like (DH52) and calcitonin-like (DH31) diuretic hormones, two ecdysis-triggering hormones, two FIRFamides, one insulin- and one each of three IGF-related peptides, two alternative splice forms of short and long ion transport peptide (ITP), one each of two N-terminally elongated ITPs, myosuppressin, neuroparsin, two neuropeptide-F splice forms, three periviscerokinins (but no pyrokinins), pigment dispersing hormone, proctolin, Met4-proctolin, one novel short neuropeptide-F, three RYamides, SIFamide, two sulfakinins, three tachykinins. Two genes encode orcokinins, three genes different allatostatins-C. Paired gene clusters occur for two novel eclosion hormones; bursicons alpha, beta; glycoproteins GPA2, GPB5; and two of the allatostatin-C genes. Detailed comparisons of genes or their products with those from insects and decapod crustaceans revealed that the D. pulex peptides are often closer to their insect than to their decapod crustacean homologues, confirming that branchiopods, to which Daphnia belongs, are the ancestor group of insects.

  • 31.
    Dircksen, Heinrich
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Skiebe, Petra
    Freie Universität Berlin.
    Abel, Britta
    University of Bonn.
    Agricola, Hans
    University of Jena.
    Buchner, Klaus
    Freie Universität Berlin.
    Muren, J. Eric
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Nässel, Dick
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Structure, distribution, and biological activity of novel members of the allatostatin family in the crayfish Orconectes limosus.1999In: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 20, no 6, p. 695-712Article in journal (Refereed)
    Abstract [en]

    In the central and peripheral nervous system of the crayfish, Orconectes limosus, neuropeptides immunoreactive to an antiserum against allatostatin I (= Dipstatin 7) of the cockroach Diploptera punctata have been detected by immunocytochemistry and a sensitive enzyme immunoassay. Abundant immunoreactivity occurs throughout the central nervous system in distinct interneurons and neurosecretory cells. The latter have terminals in well-known neurohemal organs, such as the sinus gland, the pericardial organs, and the perineural sheath of the ventral nerve cord. Nervous tissue extracts were separated by reverse-phase high-performance liquid chromatography and fractions were monitored in the enzyme immunoassay. Three of several immunopositive fractions have been purified and identified by mass spectroscopy and microsequencing as AGPYAFGL-NH2, SAGPYAFGL-NH2, and PRVYGFGL-NH2. The first peptide is identical to carcinustatin 8 previously identified in the crab Carcinus maenas. The others are novel and are designated orcostatin I and orcostatin II, respectively. All three peptides exert dramatic inhibitory effects on contractions of the crayfish hindgut. Carcinustatin 8 also inhibits induced contractions of the cockroach hindgut. Furthermore, this peptide reduces the cycle frequency of the pyloric rhythms generated by the stomatogastric nervous system of two decapod species in vitro. These crayfish allatostatin-like peptides are the first native crustacean peptides with demonstrated inhibitory actions on hindgut muscles and the pyloric rhythm of the stomatogastric ganglion.

  • 32.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Tesfai, Lily Kahsai
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Albus, Christina
    Nässel, Dick R
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Ion transport peptide splice forms in central and peripheral neurons throughout postembryogenesis of Drosophila melanogaster.2008In: The Journal of comparative neurology, ISSN 1096-9861, Vol. 509, no 1, p. 23-41Article in journal (Refereed)
    Abstract [en]

    Ion transport peptides (ITPs) belong to a large arthropod neuropeptide family including crustacean hyperglycaemic hormones and are antidiuretic hormones in locusts. Because long and short ITP isoforms are generated by alternative splicing from a single gene in locusts and moths, we investigated whether similarly spliced gene products occur in the nervous system of Drosophila melanogaster throughout postembryogenesis. The itp gene CG13586 was reanalyzed, and we found three instead of the two previously annotated alternatively spliced mRNAs. These give rise to three different neuropeptides, two long C-terminally carboxylated isoforms (DrmITPL1 and DrmITPL2, both 87 amino acids) and one short amidated DrmITP (73 amino acids), which were partially identified biochemically. Immunocytochemistry and in situ hybridization reveal nine larval and 14 adult identified neurons: four pars lateralis neurosecretory neurons, three hindgut-innervating neurons in abdominal ganglia, and a stage-specific number of interneurons and peripheral bipolar neurons. The neurosecretory neurons persist throughout postembryogenesis, form release sites in corpora cardiaca, and invade corpora allata. One type of ITP-expressing interneuron exists only in the larval and prepupal subesophageal ganglia, whereas three types of interneurons in the adult brain arise in late pupae and invade circumscribed neuropils in superior median and lateral brain areas. One peripheral bipolar and putative sensory neuron type occurs in the larval, pupal, and adult preterminal abdominal segments. Although the neurosecretory neurons may release DrmITP and DrmITPL2 into the haemolymph, possible physiological roles of the hindgut-innervating and peripheral neurons as well as the interneurons are yet to be identified.

  • 33.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Rheinische Friedrich-Wilhelms Universität, Germany.
    Webster, Simon G.
    School of Biological Sciences University of Wales, Bangor, UK.
    Keller, Rainer
    Immunocytochemical demonstration of the neurosecretory systems containing putative moult-inhibiting hormone and hyperglycemic hormone in the eyestalk of brachyuran crustaceans1988In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 251, p. 3-12Article in journal (Refereed)
    Abstract [en]

    By use of antisera raised against purified moultinhibiting (MIH) and crustacean hyperglycemic hormone (CHH) from Carcinus maenas, complete and distinct neurosecretory pathways for both hormones were demonstrated with the PAP and immunofluorescence technique. By double staining, employing a combination of silver-enhanced immunogold labelling and PAP, both antigens could be visualized in the same section. Immunoreactive structures were studied in Carcinus maenas, Liocarcinus puber, Cancer pagurus, Uca pugilator and Maja squinado. They were only observed in the X-organ sinus gland (SG) system of the eyestalks and consisted of MIH-positive perikarya, which were dispersed among the more numerous CHH-positive perikarya of the medulla terminalis X-organ (XO). The MIH-positive neurons form branching collateral plexuses adjacent to the XO and axons that are arranged around the CHH-positive central axon bundle of the principal XO-SG tract. In the SG, MIH-positive axon profiles and terminals, clustered around hemolymph lacunae, are distributed between the more abundant CHH-positive axon profiles and terminals. Colocalisation of MIH and CHH was never observed. The gross morphology of both neurosecretory systems was similar in all species examined, however, in U. pugilator and M. squinado immunostaining for MIH was relatively faint unless higher concentrations of antiserum were used. Possible reasons for this phenomenon as well as observed moult cycle-related differences in immunostaining are discussed.

  • 34.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Wilcockson, Dave C
    Webster, Simon G
    Neuropeptides in a forgotten crustacean neurohaemal organ classic, the postcomissural organs of the shrimp Palaemon serratus2005In: Comparative Biochemistry and Physiology A, ISSN 1095-6433, E-ISSN 1531-4332, Vol. 141, no 3, p. S156-S157Article in journal (Refereed)
  • 35.
    Dircksen, Heinrich
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Zahnow, Cynthia A.
    Gaus, Gabriele
    Keller, Rainer
    Rao, K. Ranga Rao
    Riehm, John P.
    The ultrastructure of nerve endings containing pigment-dispersing hormone (PDH) in crustacean sinus glands: Identification by an antiserum against a synthetic PDH1987In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 250, no 2, p. 377-387Article in journal (Refereed)
    Abstract [en]

    A high-liter antiserum has been obtained from two rabbits immunized with a glutaraldehyde conjugate of synthetic pigment-dispersing hormone (PDH) from Uca pugilator and bovine thyroglobulin. The antiserum blocked melanophore-dispersing activity of the peptide in vivo. In sinus glands (SG) of Carcinus maenas, Cancer pagurus, Uca pugilator and Orconectes limosus, electron-microscopic immunocytochemistry revealed sparsely distributed axon endings containing a distinct PDH-immunoreactive type of neurosecretory granules (diameter 90–130 nm). Exocytotic figures indicating release of the content of these granules into hemolymph lacunae were occasionally observed. Preservation of fine structure and antigenicity of the PDH granules were markedly dependent on the fixation procedure used. A preliminary experiment with C. maenas showed that preterminal axon dilatations near the basal lamina seemed to accumulate PDH-granules when animals were kept in complete darkness for three days. Immunodot blotting of fractions after high pressure liquid chromatography (HPLC) of extracts from SGs of C. maenas and O. limosus revealed a strongly immunoreactive substance at a retention time very similar to those of synthetic PDHs of Uca pugilator and Pandalus borealis. It is also coincident with a zone of biological activity. Thus, the antigen demonstrated by immunocytochemistry is identical or very similar to one of the known PDHs.

  • 36. Gruber, Barbara
    et al.
    Köster, Bärbel
    Dircksen, Heinrich
    Institute of Cytology and Micromorphology, University of Bonn, Germany.
    Korfmann, Gunter
    Rinast, Karl
    Stockem, Wilhelm
    Nahrungsaufnahme beim Pantoffeltier Paramecium caudatum. Versuche zur Phagocytose und Cyclose III.1980In: Mikrokosmos, ISSN 0026-3680, Vol. 70, p. 315-319Article in journal (Refereed)
  • 37.
    Gáliková, Martina
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology.
    The thirsty fly: Ion transport peptide (ITP) is a novel endocrine regulator of water homeostasis in Drosophila2018In: PLOS Genetics, ISSN 1553-7390, E-ISSN 1553-7404, Vol. 14, no 8, article id e1007618Article in journal (Refereed)
    Abstract [en]

    Animals need to continuously adjust their water metabolism to the internal and external conditions. Homeostasis of body fluids thus requires tight regulation of water intake and excretion, and a balance between ingestion of water and solid food. Here, we investigated how these processes are coordinated in Drosophila melanogaster. We identified the first thirst-promoting and anti-diuretic hormone of Drosophila, encoded by the gene Ion transport peptide (ITP). This endocrine regulator belongs to the CHH (crustacean hyperglycemic hormone) family of peptide hormones. Using genetic gain- and loss-of-function experiments, we show that ITP signaling acts analogous to the human vasopressin and renin-angiotensin systems; expression of ITP is elevated by dehydration of the fly, and the peptide increases thirst while repressing excretion, promoting thus conservation of water resources. ITP responds to both osmotic and desiccation stress, and dysregulation of ITP signaling compromises the fly’s ability to cope with these stressors. In addition to the regulation of thirst and excretion, ITP also suppresses food intake. Altogether, our work identifies ITP as an important endocrine regulator of thirst and excretion, which integrates water homeostasis with feeding of Drosophila.

  • 38. Harzsch, Steffen
    et al.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Beltz, Barbara S
    Development of pigment-dispersing hormone-immunoreactive neurons in the American lobster: homology to the insect circadian pacemaker system?2009In: Cell and tissue research, ISSN 1432-0878, Vol. 335, no 2, p. 417-29Article in journal (Refereed)
    Abstract [en]

    We have examined the development of pigment-dispersing hormone (PDH)-immunoreactive neurons in embryos of the American lobster Homarus americanus Milne Edwards, 1837 (Decapoda, Reptantia, Homarida) by using an antiserum against beta-PDH. This peptide is detectable in the terminal medulla of the eyestalks and the protocerebrum where PDH immunoreactivity is present as early as 20% of embryonic development. During ontogenesis, an elaborate system of PDH-immunoreactive neurons and fibres develops in the eyestalks and the protocerebrum, whereas less labelling is present in the deuto- and tritocerebrum and the ventral nerve cord. The sinus gland is innervated by PDH neurites at hatching. This pattern of PDH immunoreactivity has been compared with that found in various insect species. Neurons immunoreactive to pigment-dispersing factor in the medulla have been shown to be a central component of the system that generates the circadian rhythm in insects. Our results indicate that, in view of the position of the neuronal somata and projection patterns of their neurites, the immunolabelled medulla neurons in insects have homologous counterparts in the crustacean eyestalk. Since locomotory and other activities in crustaceans follow distinct circadian rhythms comparable with those observed in insects, we suggest that PDH-immunoreactive medulla neurons in crustaceans are involved in the generation of these rhythms.

  • 39.
    Helle, Johannes
    et al.
    Universität Göttingen.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Eckert, Manfred
    Friedrich-Schiller-Universität, Jena.
    Nässel, Dick
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Spörhase-Eichmann, Ulrike
    Universität Göttingen.
    Schürmann, Friedrich-Wilhelm
    Putative neurohemal areas in the peripheral nervous system of an insect, Gryllus bimaculatus, revealed by immunocytochemistry.1995In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 281, no 1, p. 43-61Article in journal (Refereed)
    Abstract [en]

    The morphology and position of putative neurohemal areas in the peripheral nervous system (ventral nerve cord and retrocerebral complex) of the cricket Gryllus bimaculatus are described. By using antisera to the amines dopamine, histamine, octopamine, and serotonin, and the neuropeptides crustacean cardioactive peptide, FMRFamide, leucokinin 1, and proctolin, an extensive system of varicose fibers has been detected throughout the nerves of all neuromeres, except for nerve 2 of the prothoracic ganglion. Immunoreactive varicose fibers occur mainly in a superficial position at the neurilemma, indicating neurosecretory storage and release of neuroactive compounds. The varicose fibers are projections from central or peripheral neurons that may extend over more than one segment. The peripheral fiber varicosities show segment-specific arrangements for each of the substances investigated. Immunoreactivity to histamine and octopamine is mainly found in the nerves of abdominal segments, whereas serotonin immunoreactivity is concentrated in subesophageal and terminal ganglion nerves. Immunoreactivity to FMRFamide and crustacean cardioactive peptide is widespread throughout all segments. Structures immunoreactive to leucokinin 1 are present in abdominal nerves, and proctolin immunostaining is found in the terminal ganglion and thoracic nerves. Codistribution of peripheral varicose fiber plexuses is regularly seen for amines and peptides, whereas the colocalization of substances in neurons has not been detected for any of the neuroactive compounds investigated. The varicose fiber system is regarded as complementary to the classical neurohemal organs.

  • 40. Hermann, Christiane
    et al.
    Saccon, Rachele
    Senthilan, Pingkalai R.
    Domnik, Lilith
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Yoshii, Taishi
    Helfrich-Foerster, Charlotte
    The circadian clock network in the brain of different Drosophila species2013In: Journal of Comparative Neurology, ISSN 0021-9967, E-ISSN 1096-9861, Vol. 521, no 2, p. 367-388Article in journal (Refereed)
    Abstract [en]

    Comparative studies on cellular and molecular clock mechanisms have revealed striking similarities in the organization of the clocks among different animal groups. To gain evolutionary insight into the properties of the clock network within the Drosophila genus, we analyzed sequence identities and similarities of clock protein homologues and immunostained brains of 10 different Drosophila species using antibodies against vrille (VRI), PAR-protein domain1 (PDP1), and cryptochrome (CRY). We found that the clock network of both subgenera Sophophora and Drosophila consists of all lateral and dorsal clock neuron clusters that were previously described in Drosophila melanogaster. Immunostaining against CRY and the neuropeptide pigment-dispersing factor (PDF), however, revealed species-specific differences. All species of the Drosophila subgenus and D. pseudoobscura of the Sophophora subgenus completely lacked CRY in the large ventrolateral clock neurons (lLNvs) and showed reduced PDF immunostaining in the small ventrolateral clock neurons (sLNvs). In contrast, we found the expression of the ion transport peptide (ITP) to be consistent within the fifth sLNv and one dorsolateral clock neuron (LNd) in all investigated species, suggesting a conserved putative function of this neuropeptide in the clock. We conclude that the general anatomy of the clock network is highly conserved throughout the Drosophila genus, although there is variation in PDF and CRY expression. Our comparative study is a first step toward understanding the organization of the circadian clock in Drosophila species adapted to different habitats.

  • 41. Hermann-Luibl, Christiane
    et al.
    Yoshii, Taishi
    Senthilan, Pingkalai R.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Helfrich-Förster, Charlotte
    The Ion Transport Peptide Is a New Functional Clock Neuropeptide in the Fruit Fly Drosophila melanogaster2014In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 34, no 29, p. 9522-9536Article in journal (Refereed)
    Abstract [en]

    The clock network of Drosophila melanogaster expresses various neuropeptides, but a function in clock-mediated behavioral control was so far only found for the neuropeptide pigment dispersing factor (PDF). Here, we propose a role in the control of behavioral rhythms for the ion transport peptide (ITP), which is expressed in the fifth small ventral lateral neuron, one dorsal lateral neuron, and in only a few nonclock cells in the brain. Immunocytochemical analyses revealed that ITP, like PDF, is most probably released in a rhythmic manner at projection terminals in the dorsal protocerebrum. This rhythm continues under constant dark conditions, indicating that ITP release is clock controlled. ITP expression is reduced in the hypomorph mutant ClkAR, suggesting that ITP expression is regulated by CLOCK. Using a genetically encoded RNAi construct, we knocked down ITP in the two clock cells and found that these flies show reduced evening activity and increased nocturnal activity. Overexpression of ITP with two independent timeless-GAL4 lines completely disrupted behavioral rhythms, but only slightly dampened PER cycling in important pacemaker neurons, suggesting a role for ITP in clock output pathways rather than in the communication within the clock network. Simultaneous knockdown (KD) of ITP and PDF made the flies hyperactive and almost completely arrhythmic under constant conditions. Under light-dark conditions, the double-KD combined the behavioral characteristics of the single-KD flies. In addition, it reduced the flies' sleep. We conclude that ITP and PDF are the clock's main output signals that cooperate in controlling the flies' activity rhythms.

  • 42.
    Hill, Jason
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics. Uppsala University, Sweden.
    Rastas, Pasi
    Hornett, Emily A.
    Neethiraj, Ramprasad
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Clark, Nathan
    Morehouse, Nathan
    de la Paz Celorio-Mancera, Maria
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Carnicer Cols, Jofre
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Meslin, Camille
    Keehnen, Naomi
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Pruisscher, Peter
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Sikkink, Kristin
    Vives, Maria
    Vogel, Heiko
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Woronik, Alyssa
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics. New York University, USA.
    Boggs, Carol L.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution2019In: Science Advances, E-ISSN 2375-2548, Vol. 5, no 6, article id eaau3648Article in journal (Refereed)
    Abstract [en]

    Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.

  • 43.
    Hofer, Sabine
    et al.
    Department of Biology, University of Marburg, D-35032 Marburg, Germany.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Tollbäck, Petter
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Homberg, Uwe
    Department of Biology, University of Marburg, D-35032 Marburg, Germany.
    Novel insect orcokinins: characterization and neuronal distribution in the brains of selected dicondylian insects.2005In: Journal of Comparative Neurology, ISSN 0021-9967, E-ISSN 1096-9861, Vol. 490, no 1, p. 57-71Article in journal (Refereed)
    Abstract [en]

    Orcokinins are a family of myotropic neuropeptides identified in various decapod crustaceans and recently in a cockroach. Their presence in the crustacean nervous system and hemolymph suggests that they act as hormones and as locally acting neuromodulators. To provide further evidence for the existence of orcokinins in insects, we identified a novel orcokinin-related peptide in the locust Schistocerca gregaria and used an antiserum against Asn13-orcokinin for immunostaining in the brains of selected dicondylian insects, including a silverfish, three polyneopteran species (a cockroach and two locusts), and three endopterygote species (a moth, a bee, and a fly). As analyzed by MALDI-TOF spectrometry and nanoelectrospray Q-TOF, the locust orcokinin is a novel tetradecapeptide with striking sequence similarity to crustacean orcokinins. Orcokinin immunostaining was widespread and occurred in similar patterns in the brain of the silverfish and the polyneopteran species. Prominent immunostaining was detected in the optic lobe, especially in the medulla and in the accessory medulla, in local interneurons of the antennal lobe, and in extrinsic and intrinsic mushroom-body neurons. All parts of the central complex and many other areas of the brains were densely stained. In the silverfish, the cockroach, and the locusts, processes in the corpora cardiaca showed orcokinin immunoreactivity, suggesting that orcokinins also serve a hormonal role. In contrast to the case in polyneopteran species, immunostaining was completely lacking in the brains of the honeybee, fruitfly, and sphinx moth. This indicates that orcokinins either are modified considerably or may be completely absent in the brains of endopterygote insects.

  • 44. Homberg, Uwe
    et al.
    Würden, Stefan
    Dircksen, Heinrich
    Institut für Zoophysiologie der Universität,Bonn, Germany.
    Rao, K. Ranga
    Comparative anatomy of pigment-dispersing hormone-immunoreactive neurons in the brain of orthopteroid insects1991In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 266, no 2, p. 343-357Article in journal (Refereed)
    Abstract [en]

    In a comparative study, the anatomy of neurons immunoreactive with an antiserum against the crustacean beta-pigment-dispersing hormone was investigated in the brain of several orthopteroid insects including locusts, crickets, a cockroach, and a phasmid. In all species studied, three groups of neurons with somata in the optic lobes show pigment-dispersing hormone-like immunoreactivity. Additionally, in most species, the tritocerebrum exhibits weak immunoreactive staining originating from ascending fibers, tritocerebral cells, or neurons in the inferior protocerebrum. Two of the three cell groups in the optic lobe have somata at the dorsal and ventral posterior edge of the lamina. These neurons have dense ramifications in the lamina with processes extending into the first optic chiasma and into distal layers of the medulla. Pigment-dispersing hormone-immunoreactive neurons of the third group have somata near the anterior proximal margin of the medulla. These neurons were reconstructed in Schistocerca gregaria, Locusta migratoria, Teleogryllus commodus, Periplaneta americana, and Extatosoma tiaratum. The neurons have wide and divergent arborizations in the medulla, in the lamina, and in several regions of the midbrain, including the superior and inferior lateral protocerebrum and areas between the pedunculi and alpha-lobes of the mushroom bodies. Species-specific differences were found in this third cell group with regard to the number of immunoreactive cells, midbrain arborizations, and contralateral projections, which are especially prominent in the cockroach and virtually absent in crickets. The unusual branching patterns and the special neurochemical phenotype suggest a particular physiological role of these neurons. Their possible function as circadian pacemakers is discussed.

  • 45.
    Jaros, Peter P.
    et al.
    Rheinische Friedrich-Wilhelms-Universität, Germany.
    Dircksen, Heinrich
    Rheinische Friedrich-Wilhelms-Universität, Germany.
    Keller, Rainer
    Rheinische Friedrich-Wilhelms-Universität, Germany.
    Occurrence of immunoreactive enkephalins in a neurohemal organ and other nervous structures in the eyestalk of the shore crab, Carcinus maenas L. (Crustacea, Decapoda)1985In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 241, no 1, p. 111-117Article in journal (Refereed)
    Abstract [en]

    Light-microscopical observations with immunofluorescence and peroxidase staining procedures revealed leu-enkephalin-like immunoreactivity in axon profiles of the sinus gland (SG) and in single small neurons in the optic ganglia of the eyestalk of Carcinus maenas. Electron microscopy of the SG showed reactivity to be associated with neurosecretory granules 82±23 nm in diameter. High performance liquid chromatography of SG-extracts revealed radioimmunoreactive substances with the retention times of synthetic met- and leu-enkephalin and met-enkephalin-Arg6-Phe7, respectively.

  • 46.
    Johard, Helena A D
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Yoishii, Taishi
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Cusumano, Paola
    Rouyer, Francois
    Helfrich-Förster, Charlotte
    Nässel, Dick R
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Peptidergic clock neurons in Drosophila: ion transport peptide and short neuropeptide F in subsets of dorsal and ventral lateral neurons2009In: The Journal of comparative neurology, ISSN 1096-9861, Vol. 516, no 1, p. 59-73Article in journal (Refereed)
    Abstract [en]

    About 150 clock neurons are clustered in different groups in the brain of Drosophila. Among these clock neurons, some pigment-dispersing factor (PDF)-positive and PDF-negative lateral neurons (LNs) are principal oscillators responsible for bouts of activity in the morning and evening, respectively. The full complement of neurotransmitters in these morning and evening oscillators is not known. By using a screen for candidate neuromediators in clock neurons, we discovered ion transport peptide (ITP) and short neuropeptide F (sNPF) as novel neuropeptides in subpopulations of dorsal (LN(d)s) and ventral (s-LN(v)s) LNs. Among the six LN(d)s, ITP was found in one that coexpresses long neuropeptide F (NPF) and cryptochrome. We detected sNPF in two LN(d)s that also express cryptochrome; these cells are distinct from three LN(d)s expressing NPF. Thus, we have identified neuropeptides in five of the six LN(d)s. The three LN(d)s expressing cryptochrome, with either ITP or sNPF, are the only ones with additional projections to the accessory medulla. Among the five s-LN(v)s in the adult brain, ITP was detected in the fifth neuron that is devoid of PDF and sNPF in the four neurons that also express PDF. By using a choline acetyltransferase (Cha) Gal4, we detected Cha expression in the two sNPF producing LN(d)s and in the fifth s-LN(v). In the larval brain, two of the four PDF-producing s-LN(v)s coexpress sNPF. Our findings emphasize that the LN(d)s are heterogeneous both anatomically and with respect to content of neuropeptides, cryptochrome, and other markers and suggest diverse functions of these neurons.

  • 47. Johnen, Christa
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Changes in haemolymph ecdysteroid levels and CNS contents of crustacean cardioactive peptide-immunoreactivity during the moult cycle of the isopod Oniscus asellus1995In: Netherlands journal of zoology (Print), ISSN 0028-2960, E-ISSN 1568-542X, Vol. 45, p. 38-40Article in journal (Refereed)
    Abstract [en]

    By use of newly developed enzyme immunoassays for ecdysteroids (ECD) and crustacean cardioactive peptide (CCAP) it was found (1) that in the isopod Oniscus asellus a peak occurs of hemolymph (HL)-ECD contents in prcmoult stages followed by a second but smaller peak 1 h after posterior ecdysis, and (2) that concomitantly with a drop in the first ECD-peak, CCAP-contcnts of the ventral nerve cord rise tenfold basal level around posterior ecdysis. This suggests that CCAP plays a role in isopod moulting processes.

  • 48.
    Kahsai, Lily
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Kapan, Neval
    Stockholm University, Faculty of Science, Department of Zoology.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Winther, Åsa ME
    Stockholm University, Faculty of Science, Department of Zoology.
    Nässel, Dick R
    Stockholm University, Faculty of Science, Department of Zoology.
    Metabolic stress responses in Drosophila are modulated by brain neurosecretory cells that produce multiple neuropeptides2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 7, p. e11480-Article in journal (Refereed)
    Abstract [en]

    In Drosophila, neurosecretory cells that release peptide hormones play a prominent role in the regulation of development, growth, metabolism, and reproduction. Several types of peptidergic neurosecretory cells have been identified in the brain of Drosophila with release sites in the corpora cardiaca and anterior aorta. We show here that in adult flies the products of three neuropeptide precursors are colocalized in five pairs of large protocerebral neurosecretory cells in two clusters (designated ipc-1 and ipc-2a): Drosophila tachykinin (DTK), short neuropeptide F (sNPF) and ion transport peptide (ITP). These peptides were detected by immunocytochemistry in combination with GFP expression driven by the enhancer trap Gal4 lines c929 and Kurs-6, both of which are expressed in ipc-1 and 2a cells. This mix of colocalized peptides with seemingly unrelated functions is intriguing and prompted us to initiate analysis of the function of the ten neurosecretory cells. We investigated the role of peptide signaling from large ipc-1 and 2a cells in stress responses by monitoring the effect of starvation and desiccation in flies with levels of DTK or sNPF diminished by RNA interference. Using the Gal4-UAS system we targeted the peptide knockdown specifically to ipc-1 and 2a cells with the c929 and Kurs-6 drivers. Flies with reduced DTK or sNPF levels in these cells displayed decreased survival time at desiccation and starvation, as well as increased water loss at desiccation. Our data suggest that homeostasis during metabolic stress requires intact peptide signaling by ipc-1 and 2a neurosecretory cells.

  • 49. Klepsatel, Peter
    et al.
    Nagaraj Girish, Thirnahalli
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Gáliková, Martina
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Slovak Academy of Sciences, Slovakia.
    Reproductive fitness of Drosophila is maximised by optimal developmental temperature2019In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 222, no 10, article id 202184Article in journal (Refereed)
    Abstract [en]

    Whether the character of developmental plasticity is adaptive or non-adaptive has often been a matter of controversy. Although thermal developmental plasticity has been studied in Drosophila for several traits, it is not entirely clear how it affects reproductive fitness. We, therefore, investigated how developmental temperature affects reproductive performance (early fecundity and egg-to-adult viability) of wild-caught Drosophila melanogaster. We have tested competing hypotheses on the character of developmental thermal plasticity using a full factorial design with three developmental and adulthood temperatures within the natural thermal range of this species. To account for potential intraspecific differences, we examined flies from tropical (India) and temperate (Slovakia) climate zones. Our results show that flies from both populations raised at intermediate developmental temperature (25°C) have comparable or higher early fecundity and fertility at all tested adulthood temperatures, while lower (17°C) or higher developmental temperatures (29°C) did not entail any advantage under the tested thermal regimes. Importantly, the superior thermal performance of flies raised at 25°C is apparent even after taking two traits positively associated with reproductive output into account – body size and ovariole number. Thus, in Drosophila melanogaster, development at a given temperature does not necessarily provide any advantage at this thermal environment in terms of reproductive fitness. Our findings strongly support the optimal developmental temperature hypothesis which claims that at different thermal environments the highest fitness is achieved when an organism is raised at its optimal developmental temperature.

  • 50.
    Kress, Timm
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Harzsch, Steffen
    University of Greifswald, Germany.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Neuroanatomy of the optic ganglia and central brain of the water flea Daphnia magna (Crustacea, Cladocera)2016In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 363, no 3, p. 649-677Article in journal (Refereed)
    Abstract [en]

    We reveal the neuroanatomy of the optic ganglia and central brain in the water flea Daphnia magna by use of classical neuroanatomical techniques such as semi-thin sectioning and neuronal backfilling, as well as immunohistochemical markers for synapsins, various neuropeptides and the neurotransmitter histamine. We provide structural details of distinct neuropiles, tracts and commissures, many of which were previously undescribed. We analyse morphological details of most neuron types, which allow for unravelling the connectivities between various substructural parts of the optic ganglia and the central brain and of ascending and descending connections with the ventral nerve cord. We identify 5 allatostatin-A-like, 13 FMRFamide-like and 5 tachykinin-like neuropeptidergic neuron types and 6 histamine-immunoreactive neuron types. In addition, novel aspects of several known pigment-dispersing hormone-immunoreactive neurons are re-examined. We analyse primary and putative secondary olfactory pathways and neuronal elements of the water flea central complex, which displays both insect- and decapod crustacean-like features, such as the protocerebral bridge, central body and lateral accessory lobes. Phylogenetic aspects based upon structural comparisons are discussed as well as functional implications envisaging more specific future analyses of ecotoxicological and endocrine disrupting environmental chemicals.

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