A CRY FROM THE KRILL Gabriella M. Mazzotta, 1 Cristiano De Pittà, 2 Clara Benna, 1 Silvio C. E. Tosatto, 1 Gerolamo Lanfranchi, 2 Cristiano Bertolucci, 3 and Rodolfo Costa 1 1 Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy 2 CRIBI Biotechnology Centre, Università degli Studi di Padova, Padova, Italy 3 Dipartimento di Biologia ed Evoluzione, Università degli Studi di Ferrara, Ferrara, Italy Antarctic krill (Euphausia superba) inhabit a region with strong seasonality in several parameters, such as photoperiod, light intensity, extent of sea ice, and food availability. In particular, seasonal changes in environmental light regimes have been shown to strongly influence krill metabolism, representing control signals for seasonal regulation of physiology of this key Southern Ocean species. Here, we report the identification of a cryptochrome gene, a cardinal component of the clockwork machinery in several organisms. EsCRY appears to be an ortholog of mammalian-like CRYs and clusters with the insect CRY2 subfamily. EsCRY has the canonical bipartite CRY structure, with a conserved N-terminal domain and a highly divergent C-terminus, that bears several binding motifs, some of them shared with insect CRY2 and others peculiar for EsCRY. We have evaluated the temporal expression of Escry both at mRNA and protein levels in individuals harvested from the Ross Sea at different times throughout the 24 h cycle during the Antarctic summer. We observed a daily fluctuation in abundance for Escry mRNA in the head, with high levels around 06:00 h, which is not mirrored by a cycle in the corresponding protein. Our findings represent a first step toward establishing the presence of an endogenous circadian time-keeping mechanism that might allow this organism to synchronize its physiology and behavior to the Antarctic light regimes. (Author correspondence: bru@unife.it or rodolfo.costa@unipd.it) Keywords Euphausia superba; Circadian clock; Cryptochrome; Phylogeny; Gene expression Sources of support: This work was supported by the Italian Programma Nazionale di Ricerche in Antartide – PNRA (grant 2003/1.3 and grant 2005/1.04 to RC and CB). RC also thanks the European Community (6th Framework Project EUCLOCK No. 018741) and the Italian Space Agency (DCMC grant). CB also thanks University of Ferrara research grants. C. Benna was supported by the University of Padova (Assegno di Ricerca CPDR042471). The first two authors equally contributed to the work described in this paper. Address correspondence to C. Bertolucci, Dipartimento di Biologia ed Evoluzione, Università degli Studi di Ferrara, Via L. Borsari, 46, 44100 Ferrara, Italy; Tel.: +39-0532-455485; Fax: +39- 0532-207143, E-mail: bru@unife.it; or R. Costa, Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi, 58/B, 35121, Padova, Italy; Tel.: +39-049-8276217; Fax: +39-049-8276209, E-mail: rodolfo.costa@unipd.it Submitted August 21, 2009, Returned for revision September 16, 2009, Accepted December 4, 2009 Chronobiology International, 27(3): 425–445, (2010) Copyright © Informa UK Ltd. ISSN 0742-0528 print/1525-6073 online DOI: 10.3109/07420521003697494 425 Chronobiol Int Downloaded from informahealthcare.com by University of Padova on 06/04/10 For personal use only.