--- res: bibo_abstract: - Light represents the principal signal driving circadian clock entrainment. However, how light influences the evolution of the clock remains poorly understood. The cavefish Phreatichthys andruzzii represents a fascinating model to explore how evolution under extreme aphotic conditions shapes the circadian clock, since in this species the clock is unresponsive to light. We have previously demonstrated that loss-of-function mutations targeting non-visual opsins contribute in part to this blind clock phenotype. Here, we have compared orthologs of two core clock genes that play a key role in photic entrainment, cry1a and per2, in both zebrafish and P. andruzzii. We encountered aberrantly spliced variants for the P. andruzzii per2 transcript. The most abundant transcript encodes a truncated protein lacking the C-terminal Cry binding domain and incorporating an intronic, transposon-derived coding sequence. We demonstrate that the transposon insertion leads to a predominantly cytoplasmic localization of the cavefish Per2 protein in contrast to the zebrafish ortholog which is distributed in both the nucleus and cytoplasm. Thus, it seems that during evolution in complete darkness, the photic entrainment pathway of the circadian clock has been subject to mutation at multiple levels, extending from opsin photoreceptors to nuclear effectors.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Rosa Maria foaf_name: Ceinos, Rosa Maria foaf_surname: Ceinos - foaf_Person: foaf_givenName: Elena foaf_name: Frigato, Elena foaf_surname: Frigato - foaf_Person: foaf_givenName: Cristina foaf_name: Pagano, Cristina foaf_surname: Pagano - foaf_Person: foaf_givenName: Nadine foaf_name: Frohlich, Nadine foaf_surname: Frohlich - foaf_Person: foaf_givenName: Pietro foaf_name: Negrini, Pietro foaf_surname: Negrini - foaf_Person: foaf_givenName: Nicola foaf_name: Cavallari, Nicola foaf_surname: Cavallari foaf_workInfoHomepage: http://www.librecat.org/personId=457160E6-F248-11E8-B48F-1D18A9856A87 - foaf_Person: foaf_givenName: Daniela foaf_name: Vallone, Daniela foaf_surname: Vallone - foaf_Person: foaf_givenName: Silvia foaf_name: Fuselli, Silvia foaf_surname: Fuselli - foaf_Person: foaf_givenName: Cristiano foaf_name: Bertolucci, Cristiano foaf_surname: Bertolucci - foaf_Person: foaf_givenName: Nicholas S foaf_name: Foulkes, Nicholas S foaf_surname: Foulkes bibo_doi: 10.1038/s41598-018-27080-2 bibo_issue: '1' bibo_volume: 8 dct_date: 2018^xs_gYear dct_identifier: - UT:000434640800008 dct_language: eng dct_publisher: Nature Publishing Group@ dct_title: Mutations in blind cavefish target the light regulated circadian clock gene period 2@ ...