Classes of retrotransposons constitute a large portion of metazoan genome. There have been cases re- ported that genomic abundance of retrotransposons is correlated with the severity of low environmental temperatures. However, the molecular mechanisms underlying such correlation are unknown. We show here by cell transfection assays that retrotransposition （RTP） of a long interspersed nuclear element （LINE） from an Antarctic nototbenioid fish Dissostichus mawsoni （droLl） could be activated by low temperature exposure, causing increased dmLl copies in the host cell genome. The cold-induced droll propagation was demonstrated to be mediated by the mitogen-activated protein kinases （MAPK）]p38 signaling pathway, which is activated by accumulation of reactive oxygen species （ROS） in cold-stressed conditions. Surprisingly, droLl transfected cells showed an increase in the number of viable cells after prolonged cold exposures than non-transfected cells. Features of cold inducibility of dmLl were reca- pitulated in LINEs of zebrafish origin both in cultured cell lines and tissues, suggesting existence of a common cold-induced LINE amplification in fishes. The findings reveal an important function of LINEs in temperature adaptation and provid insights into the MAPK/p38 stress responsive pathway that shapes LINE composition in fishes facing cold stresses. Copyright 2017, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Limited and Science Press. All rights reserved.
