Adult Circadian Behavior in Drosophila Requires Developmental Expression of cycle, But Not period

Abstract

Circadian clocks have evolved as internal time keeping mechanisms that allow anticipation of daily environmental changes and organization of a daily program of physiological and behavioral rhythms. To better examine the mechanisms underlying circadian clocks in animals and to ask whether clock gene expression and function during development affected subsequent daily time keeping in the adult, we used the genetic tools available in Drosophila to conditionally manipulate the function of the CYCLE component of the positive regulator CLOCK/CYCLE (CLK/CYC) or its negative feedback inhibitor PERIOD (PER). Differential manipulation of clock function during development and in adulthood indicated that there is no developmental requirement for either a running clock mechanism or expression of per. However, conditional suppression of CLK/CYC activity either via per over-expression or cyc depletion during metamorphosis resulted in persistent arrhythmic behavior in the adult. Two distinct mechanisms were identified that may contribute to this developmental function of CLK/CYC and both involve the ventral lateral clock neurons (LNvs) that are crucial to circadian control of locomotor behavior: (1) selective depletion of cyc expression in the LNvs resulted in abnormal peptidergic small-LNv dorsal projections, and (2) PER expression rhythms in the adult LNvs appeared to be affected by developmental inhibition of CLK/CYC activity. Given the conservation of clock genes and circuits among animals, this study provides a rationale for investigating a possible similar developmental role of the homologous mammalian CLOCK/BMAL1 complex.

Drosophila Clock Is Required in Brain Pacemaker Neurons to Prevent Premature Locomotor Aging Independently of Its Circadian Function

“…s-LNv projections were impaired in the cyc 0 mutant, as previously shown [38, 39], but not in the Clk AR mutant. This difference does not seem to play a part in the differential impact of the two mutants on ARLI, since s-LNv projections appeared completely wild-type when expressing RNAi for either cyc or Clk in the PDF neurons.…”

“…Note that projections from the s-LNv appeared wild-type in the Clk AR , Clk RNAi - and cyc RNAi -expressing flies, while they were disrupted in cyc 0 flies (S7–S9 Figs), as previously reported for both cyc 0 and Clk Jrk [38, 39]. Indeed one of the reasons that prompted us to analyze the Clk AR rather than the Clk Jrk mutant was to avoid such a developmental effect, another one being the known dominant-negative character of Clk Jrk [40].…”

NAT1/DAP5/p97 and Atypical Translational Control in the Drosophila Circadian Oscillator

“…Because some circadian genes are required during development for proper circadian rhythms in adults (Huang et al 2009;Goda et al 2011) and because NAT1 alleles have been reported to cause developmental lethality (Takahashi et al 2005), we asked whether a comparable period effect would result if we restricted the knockdown to adult circadian cells. This was done by coexpressing a temperaturesensitive GAL80 transgene driven by the ubiquitous tubulin promoter along with tim .…”

A New Promoter Element Associated with Daily Time Keeping in Drosophila

“…qRT-PCR expression analyses were carried out as described previously (22,23). Slob or Pdp1 4xCATAC-luciferase flies were entrained to 12 h light/12 h dark cycles at 25…”

“…The RNA samples were then analyzed with the SensiFAST SYBR No-ROX One-Step qPCR Kit (Bioline) using experimental primer pairs designed to specifically amplify fragments of the circadian Pdp1 or Slob transcripts, the transgenic luciferase transcript or the EF1β control transcript (see Supplementary Table S1). All primers and amplicons used in this study have been described before (22,23 • C to 95…”