Höring Flavia, Biscontin Alberto, Harms Lars, Sales Gabriele, Reiss Christian S, De Pittà Cristiano, Meyer Bettina
Alfred Wegener Institute Helmholtz Centre for Polar und Marine Research, Am Handelshafen 12, Bremerhaven, Germany; Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26111 Oldenburg, Germany.
Dipartimento di Biologia, Università degli Studi di Padova, via Ugo Bassi 58b, 35121 Padova, Italy.
Mar Genomics. 2021 Apr;56:100806. doi: 10.1016/j.margen.2020.100806. Epub 2020 Aug 7.
The Antarctic krill, Euphausia superba, has evolved seasonal rhythms of physiology and behaviour to survive under the extreme photoperiodic conditions in the Southern Ocean. However, the molecular mechanisms generating these rhythms remain far from understood. The aim of this study was to investigate seasonal differences in gene expression in three different latitudinal regions (South Georgia, South Orkneys/Bransfield Strait, Lazarev Sea) and to identify genes with potential regulatory roles in the seasonal life cycle of Antarctic krill. The RNA-seq data were analysed (a) for seasonal differences between summer and winter krill sampled from each region, and (b) for regional differences within each season. A large majority of genes showed an up-regulation in summer krill in all regions with respect to winter krill. However, seasonal differences in gene expression were less pronounced in Antarctic krill from South Georgia, most likely due to the milder seasonal conditions of the lower latitudes of this region, with a less extreme light regime and food availability between summer and winter. Our results suggest that in the South Orkneys/Bransfield Strait and Lazarev Sea region, Antarctic krill entered a state of metabolic depression and regressed development (winter quiescence) in winter. Moreover, seasonal gene expression signatures seem to be driven by a photoperiodic timing system that may adapt the flexible behaviour and physiology of Antarctic krill to the highly seasonal environment according to the latitudinal region. However, at the lower latitude South Georgia region, food availability might represent the main environmental cue influencing seasonal physiology.
南极磷虾（Euphausia superba）已经进化出了生理和行为的季节性节律，以便在南大洋极端的光周期条件下生存。然而，产生这些节律的分子机制仍远未被理解。本研究的目的是调查三个不同纬度区域（南乔治亚岛、南奥克尼群岛/布兰斯菲尔德海峡、拉扎列夫海）基因表达的季节性差异，并鉴定在南极磷虾季节性生命周期中具有潜在调控作用的基因。对RNA测序数据进行了分析：（a）比较每个区域夏季和冬季采样的磷虾之间的季节性差异，以及（b）每个季节内的区域差异。绝大多数基因在所有区域的夏季磷虾中相对于冬季磷虾呈现上调。然而，南乔治亚岛的南极磷虾基因表达的季节性差异不太明显，这很可能是由于该区域较低纬度的季节性条件较为温和，夏季和冬季之间的光照模式和食物可利用性不那么极端。我们的结果表明，在南奥克尼群岛/布兰斯菲尔德海峡和拉扎列夫海区域，南极磷虾在冬季进入了代谢抑制和发育倒退（冬季静止）状态。此外，季节性基因表达特征似乎由一个光周期计时系统驱动，该系统可能根据纬度区域使南极磷虾灵活的行为和生理适应高度季节性的环境。然而，在较低纬度的南乔治亚岛区域，食物可利用性可能是影响季节性生理的主要环境线索。
