Circadian oscillations of RPCH gene expression in the eyestalk of the crayfish Cherax quadricarinatus

The RPCH and β-actin cDNAs from the crayfish Cherax quadricarinatus were amplified, cloned and sequenced. The primary structure sequences of these cDNAs were compared to other members of the AKH/RPCH family. Fluctuations in the amount of the C. quadricarinatus RPCH and β-actin mRNAs, as cDNAs, were quantified every 3 h by RT-PCR. Single cosinor analysis supports the notion of β-actin and RPCH mRNA circadian behavior in animals subjected to 12 h:12 h light/dark regimes. In constant darkness RPCH mRNA concentration changes to ultradian cycles.