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Cloning, sequencing and In situ localisation of guppy brain aromatase, cyp19b
Stockholm University, Faculty of Science, Department of Zoology. (HOL)
Karolinska Institutet.
(English)Manuscript (Other academic)
Abstract [en]

Oestrogens are biosynthesised by cytochrome p450-aromatase (Cyp19). Brain oestrogens serve several important functions of which nerve protection, cell proliferation, nerve development and behaviour control are a few. Teleost brain aromatase activity is exceptionally high (between 100-1000 times) compared to mammals and birds. We have successfully cloned and sequenced a 950 bp long partial fragment of the guppy CYP19B gene (PrCyp19b) derived from adult brain mRNA. Sequence alignment of translated amino acid sequence shows PrCYP19b having high sequence similarity to teleost brain aromatase. Anatomical distribution of PrCYP19b expression in adult guppy brains was studied using in situ-hybridisation with an antisense riboprobe synthesised from the cloned PrCYP19b gene. Expression of brain aromatase appeared at ventricular surfaces of the ventral telencephalic zones and the pre-optic area, in the hypothalamus, the pituitary gland, optic tectum and the cerebellum. This pattern is similar to previously reported distribution of brain aromatase in other teleosts. Measurement of brain aromatase activity in telencephalon, mesencephalon/diencephalon and rhombencephalon revealed female guppies producing the most oestrogens in mesencephalon/diencephalon, whereas males produces the most oestrogens in both telencephalon and mesencephalon/diencephalon. This indicates that brain oestrogen production is sexually dimorphic in the guppy and may serve different functions in the two genders.

Keyword [en]
Brain aromatase, teleost brain, In Situ-hybridisation, anatomical distribution
National Category
Zoology
Research subject
Functional Zoomorphology
Identifiers
URN: urn:nbn:se:su:diva-26905OAI: oai:DiVA.org:su-26905DiVA: diva2:211937
Projects
Aromatase and androgens in fish reproductive behaviour
Available from: 2009-04-20 Created: 2009-04-17 Last updated: 2010-01-14Bibliographically approved
In thesis
1. Brain Aromatase in the guppy, Poecilia reticulata: Distribution, control and role in behaviour
Open this publication in new window or tab >>Brain Aromatase in the guppy, Poecilia reticulata: Distribution, control and role in behaviour
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Oestrogens are produced by aromatisation of androgens by the aromatase enzyme. In the vertebrate brain this synthesis has vital functions in nerve protection, cell proliferation and nerve development during injury respectively brain development. Brain oestrogens are also crucial in activating certain reproductive and aggressive behaviours in mammals and birds. Teleosts have remarkably high activity of brain aromatase (bAA) compared to mammals and birds; 100-1000 times higher in brain regions like the hypothalamus, pre-optic area and optic tectum. The role of brain oestrogens in teleost behaviour is, however, less clear than in e.g. songbirds and rodents. This thesis studies the potential role of brain aromatase and brain oestrogens in the reproductive behaviour of the guppy male (Poecilia reticulata), how guppy brain aromatase responds to steroids and is distributed in the adult brain.

The thesis shows that male behaviour can be affected by brain aromatase. Reduction of bAA by aromatase inhibitor treatment reduced the sexual behaviours sigmoid display and gonopodium swinging (I) and oestrogen receptor blocking with an oestrogen antagonist reduced the number of successful mating attempts (II). The anatomical study (IV) showed that brain aromatase is distributed in areas of the adult guppy brain that are connected to reproductive control and behaviour in vertebrates.

Guppy bAA is stimulated by both androgens and oestrogens (III) but is more sensitive to oestrogens, especially in males, and could thus be used as an indicator of endocrine disruption at low concentrations found in the environment.

The thesis can also conclude that females possess more brain aromatase than males, and that although it is expressed in the same pattern throughout the brain in both genders the enzymatic activity is differently distributed between the sexes.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2009. 41 p.
Series
Södertörn Doctoral Dissertations, ISSN 1652-7399 ; 36
Keyword
Oestrogen production, behaviour, anatomy, endocrinology, bio markers, endocrine disruption
National Category
Microbiology
Research subject
Functional Zoomorphology
Identifiers
urn:nbn:se:su:diva-26942 (URN)978-91-86069-03-2 (ISBN)978-91-7155-870-1 (ISBN)
Public defence
2009-05-26, MA624, Södertörns högskola, Alfred Nobels allé 7, Huddinge, 10:00 (English)
Opponent
Supervisors
Projects
Aromatase and androgens in fish reproductive behaviour
Available from: 2009-05-05 Created: 2009-04-20 Last updated: 2009-06-09Bibliographically approved

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