Circadian rhythm - fly - Apis mellifera (honey bee)

Circadian rhythm is an internal biological clock, which enables to sustain an approximately 24-hour rhythm in the absence of environmental cues. In the fruit fly Drosophila melanogaster, seven genes that contribute to the central clock function are known: period (per), timeless (tim), Clock (Clk), cycle (cyc), vrille (vri), double-time (dbt), and shaggy (sgg). The core of the circadian clock consists of molecular feedback loops where per and tim gene products (PER and TIM proteins) eventually turn off their own transcription. The CLK/CYC heterodimer activates transcription of per and tim genes, while the PER and TIM repressor proteins accumulate in the cytoplasm. After nuclear entry of PER and TIM, transcription is inhibited by direct binding of the PER/TIM heterodimer to the CLK/CYC heterodimer. This shutoff lasts until the PER and TIM proteins are degraded allowing a new round of transcription to occur.

Organismal Systems; Environmental adaptation

Apis mellifera (honey bee) [GN:ame]

PMID:12015613

Panda S, Hogenesch JB, Kay SA.

Circadian rhythms from flies to human.

Nature 417:329-35 (2002)

PMID:11687489

Harmer SL, Panda S, Kay SA.

Molecular bases of circadian rhythms.

Annu Rev Cell Dev Biol 17:215-53 (2001)

PMID:11533719

Young MW, Kay SA.

Time zones: a comparative genetics of circadian clocks.

Nat Rev Genet 2:702-15 (2001)

PMID:12581523

Cyran SA, Buchsbaum AM, Reddy KL, Lin MC, Glossop NR, Hardin PE, Young MW, Storti RV, Blau J.

vrille, Pdp1, and dClock form a second feedback loop in the Drosophila circadian clock.

Cell 112:329-41 (2003)

PMID:16351879

Helfrich-Forster C

The circadian system of Drosophila melanogaster and its light input pathways.

Zoology (Jena) 105:297-312 (2002)

PMID:12486701

Stanewsky R

Genetic analysis of the circadian system in Drosophila melanogaster and mammals.

J Neurobiol 54:111-47 (2003)