title: Circadian phenotypes of Drosophila fragile x mutants in alternative genetic backgrounds.
abstract: Drosophila FMR1 mutants are models of human fragile X syndrome. They show a loss of locomotor activity rhythm and severe degradation of eclosion timing. We analyzed the circadian behavior of FMR1 mutants (dfmr1B55) in two genetic backgrounds, yellow white (yw) and Canton S (CS). The arrhythmic phenotype of circadian locomotor activity in constant darkness (DD) did not significantly change in either genetic background. Surprisingly, eclosion timing was completely restored by backcrossing dfmr1B55 with yw or CS flies. Morphological analysis of the small ventrally located lateral neurons of FMR1 mutants revealed that the dorsal-projection area was significantly larger in arrhythmic than rhythmic flies. In addition, dfmr1B55 mutants in both genetic backgrounds had a significantly lower evening peak in the light-dark (LD) cycle. These results indicate that lack of FMR1 does not affect eclosion timing, but alters locomotor activity patterns in both LD and DD conditions by affecting the arborization of small ventrally located lateral neurons. Thus, the FMR1 gene may regulate the circadian-related locomotor activity of Drosophila.
authors.affiliation: National Institute of Agrobiological Science, Tsukuba, Ibaraki, Japan.
authors.forename: Tatsumori
authors.initials: T
authors.lastname: Sekine
authors.forename: Terumi
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Kunikatsu
authors.initials: K
authors.lastname: Hamano
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Siomi
authors.forename: Lino
authors.initials: L
authors.lastname: Saez
authors.forename: Norio
authors.initials: N
authors.lastname: Ishida
authors.forename: Masami
authors.initials: M
authors.lastname: Shimoda
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics* / Q000502:physiology; D003433:Crosses, Genetic; D017931:DNA Primers / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics*; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics*; D007150:Immunohistochemistry; D008124:Locomotion / Q000235:genetics* / Q000502:physiology; D008156:Luciferases; D009154:Mutation / Q000235:genetics*; D009474:Neurons / Q000166:cytology; D010641:Phenotype; D017440:Photoperiod; D013997:Time Factors
chemical_list: D017931:DNA Primers; D029721:Drosophila Proteins; D051860:Fragile X Messenger Ribonucleoprotein 1; D008156:Luciferases; C467328:FMR1 protein, Drosophila