title: Clock genes period and timeless are rhythmically expressed in brains of newly hatched, photosensitive larvae of the fly, Sarcophaga crassipalpis.
abstract: While roles of the clock genes period (per) and timeless (tim) are relatively well understood in relation to circadian clocks, their potential roles in insect photoperiodism remain enigmatic. In this study, the expression of per and tim genes under two contrasting photoperiods is described in the central nervous system of photoperiodically sensitive, newly hatched first instar larvae of the flesh fly, Sarcophaga crassipalpis. Using qPCR, diel oscillations were observed in the mRNA levels of both genes under long-day (15 h light:9h dark, promotes direct development) and short-day conditions (11 h light:13 h dark, induces pupal diapause). Peak per and tim mRNA oscillations were closely associated with the light/dark transition. The conspicuous difference between the two photoperiodic conditions was that the sharp increase in per and tim mRNA abundance occurred during the light phase under long days but during the dark phase under short days. The diel oscillations were, at least in part, driven by an endogenous component, as demonstrated by transferring larvae to continuous darkness. The cells displaying Tim- and Per-like immunoreactivities (Tim- and Per-LIRs) were localized using anti-Drosophila-Per and anti-Chymomyza-Tim antibodies. Per-LIR and Tim-LIR co-localized in three groups of cells in each brain hemisphere. Two other groups, one in the brain hemispheres and the other in the fused ventral nerve ganglion, expressed only the Per-LIR.
authors.affiliation: Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Entomology, Branisovská 31, Ceské Budejovice 370 05, Czech Republic. kostal@entu.cas.cz
authors.forename: Vladimír
authors.initials: V
authors.lastname: Kostál
authors.forename: Radka
authors.initials: R
authors.lastname: Závodská
authors.forename: David
authors.initials: D
authors.lastname: Denlinger
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000528:radiation effects; D002940:Circadian Rhythm / Q000528:radiation effects; D004175:Diptera / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D005260:Female; D015870:Gene Expression / Q000528:radiation effects; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D017440:Photoperiod; D021381:Protein Transport
chemical_list: D019476:Insect Proteins