The Cryptochrome1 (cry1) Gene has Oscillating Expression Under Short and Long Photoperiods in Sesamia nonagrioides

A In order to understand whether and how the circadian system is connected to photoperiodism, an important piece of information is whether clock genes products oscillate and how they react to a changing photoperiod. In the moth Sesamia nonagrioides, which undergoes a facultive diapause controlled by photoperiod, we isolated the clock gene cryptochrome1 (cry1), named Sncry1. Sncry1 consists of 1762 bp encoding a polypeptide of 528 amino acid residues. SnCRY1 presented two characteristic conserved domains: the DNA photolyase and the Flavin-Adenine Dinucleotide (FAD) binding domain, which been demonstrated to be sufficient for light detection and phototransduction in Drosophila. SnCRY1 had significant homology with the CRY1 sequences identified from other insects. We also investigated the expression patterns of Sncry1 in brain of larvae growing under long-day 16L: 8D (LD), constant darkness (DD) and short-day 10L: 14D (SD) conditions using qRT-PCR assays. The mRNAs of Sncry1 expression was rhythmic in LD, DD and SD cycles. Sncry1 abundance tended to decrease during the day and then increase in the night. It is remarkable that the photoperiodic conditions affected the expression patterns and/or amplitudes of circadian clock gene Sncry1. Our data indicate that this gene may be associated with diapause in S. nonagrioides, because under SD (diapause conditions) the photoperiodic signal altered mRNA accumulation. Keywords: Circadian clock; Cryptochrome; Photoperiodism; Diapause; Sesamia nonagrioides