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Molecular evolution of circadian clock genes in spotted gar (Lepisosteus oculatus)

2019年05月28日 09:23  点击:[]

报告时间:2019-06-01 9:00

报告地点:西山湖校区三教D区七鳃鳗中心

报告人:孙毅

主办单位:生命科学学院

报告时间:2019-06-01 9:00

报告地点:西山湖校区三教D区七鳃鳗中心

报告人:孙毅

主办单位:生命科学学院

报告人简介:

孙毅,男,1977年出生于江苏省徐州市。1999年本科毕业于南京师范大学,2005年硕士研究生毕业于辽宁师范大学,2008年博士研究生毕业于厦门大学,获动物学博士学位。2009年至2011年在华东师范大学生命科学学院从事博士后研究,2012年1月起在苏州大学基础医学与生物科学学院任职,副教授。兼职中国中西医结合学会时间生物学委员会青年委员。

报告简介:

Circadian rhythms are biological rhythms with a period of approximately 24 hours. While canonical circadian clock genes and their regulatory mechanisms appear highly conserved, the evolution of clock gene families is still unclear due to several rounds of whole genome duplication in vertebrates. The spotted gar (Lepisosteus oculatus) as a non-teleost ray-finned fish represents a fish lineage that diverged before the teleost genome duplication (TGD), providing an outgroup for exploring the evolutionary mechanisms of circadian clocks after whole-genome duplication. In this study, we interrogated the spotted gar draft genome sequences and found that spotted gar contains 26 circadian clock genes from 11 families. Phylogenetic analysis showed that 9 of these 11 spotted gar circadian clock gene families have the same number of genes as humans, while the members of the nfil3 and cry families are different between spotted gar and humans. Using phylogenetic and syntenic analyses, we found that nfil3-1 are conserved in vertebrates. And nfil3-2 and nfil3-3 are maintained in spotted gar, teleost fishes, amphibians and reptiles also, but the orthologs have been lost in all mammals. Following the two-round vertebrate genome duplication (VGD), spotted gar retained cry1a, cry1b and cry2. In addition, spotted gar, teleost fishes, turtle and birds each have one cry3 while mammals lack of. We hypothesize that duplication of core clock genes (nfil3 and cry) in spotted gar likely facilitated a diversity of circadian regulatory mechanisms, regulating local peripheral circadian oscillators. Moreover, we also found that transcription factor binding element (Arnt::Ahr) is only retained in one of the per1 or per2 paralogs in the teleost family whose per1 or per2 genes have been duplicated from the TGD. Our research implies that the evolution of some clock gene families is different between teleosts (even without additional teleost genome duplication) and mammals. These results will help to decipher the repertoires of the spotted gar circadian system, and shed light on how the vertebrate circadian clock systems have evolved.

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