Meeting Abstract
The circadian rhythm is important to all organisms and plays a key role in physiology. Although much is known about the genetic regulation of the circadian clock in Drosophila melanogaster and in Mus musculus, less is known about the circadian clock in lower metazoans. This study attempts to fill the information gap between Cnidaria and higher metazoans by characterizing the core circadian clock of Isodiametra pulchra (Acoelomorpha). Isodiametra are marine worms that are exposed to a wide array of daily environmental changes. I. pulchra circadian core-clock mRNA sequences were identified by blasting Drosophila and Mus protein orthologues for CLOCK, CYCLE/BMAL, ARNT, PERIOD (PER), TIMELESS (TIM1), and TIMEOUT (TIM2) identified in NCBI against an I. pulchra transcriptome. Three full-length I. pulchra sequences and two incomplete I. pulchra sequences were identified. I. pulchra protein sequences were aligned with other circadian proteins found in a wide variety of organisms identified through NCBI searches and maximum likelihood trees were constructed. The results reveled that I. pulchra has an ARNT orthologue, a TIM2 orthologue, and a PER orthologue. Additionally, I examined the variation in mRNA expression at two time points using sqRT-PCR approach for I. pulchra ARNT and I. pulchra PER. I found that I. pulchra ARNT varied in a circadian fashion where expression was highest one hour before lights on, while I. pulchra PER did not vary significantly in expression between the two time points. The I. pulchra circadian clock is the most primitive bilaterian clock studied to date. I am grateful to the Ladurner lab (Univ. of Innsbruck) and the Reddien lab (MIT) for sharing the unpublished transcriptomes, and to SCINBRE (NCRR 5 P2O RR016461 and NIGMS 8 P20 GM103499).
