Rhythmic Changes in Synapse Numbers in Drosophila melanogaster Motor Terminals
2013 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 8, no 6, e67161Article in journal (Refereed) Published
Previous studies have shown that the morphology of the neuromuscular junction of the flight motor neuron MN5 in Drosophila melanogaster undergoes daily rhythmical changes, with smaller synaptic boutons during the night, when the fly is resting, than during the day, when the fly is active. With electron microscopy and laser confocal microscopy, we searched for a rhythmic change in synapse numbers in this neuron, both under light: darkness (LD) cycles and constant darkness (DD). We expected the number of synapses to increase during the morning, when the fly has an intense phase of locomotion activity under LD and DD. Surprisingly, only our DD data were consistent with this hypothesis. In LD, we found more synapses at midnight than at midday. We propose that under LD conditions, there is a daily rhythm of formation of new synapses in the dark phase, when the fly is resting, and disassembly over the light phase, when the fly is active. Several parameters appeared to be light dependent, since they were affected differently under LD or DD. The great majority of boutons containing synapses had only one and very few had either two or more, with a 70:25:5 ratio (one, two and three or more synapses) in LD and 75:20:5 in DD. Given the maintenance of this proportion even when both bouton and synapse numbers changed with time, we suggest that there is a homeostatic mechanism regulating synapse distribution among MN5 boutons.
Place, publisher, year, edition, pages
2013. Vol. 8, no 6, e67161
Zoology Cell Biology
IdentifiersURN: urn:nbn:se:su:diva-92809DOI: 10.1371/journal.pone.0067161ISI: 000321148400039OAI: oai:DiVA.org:su-92809DiVA: diva2:642601
Programa de Desarrollo Tecnologico 058-54; Swedish Research Council; Programa de Deserrollo de las Ciencias Basicas (PEDECIBA;) Tullberg Foundation (Uppsala University); Silen Foundation (Stockholm University); Boehringer Ingelheim Fonds; NICHD 2013-08-222013-08-202015-07-07Bibliographically approved