Transcriptional response to low temperature in the yellow drum (Nibea albiflora) and identification of genes related to cold stress. Xu Dongdong,You Qiaochu,Chi Changfeng,Luo Shengyu,Song Hongbin,Lou Bao,Takeuchi Yutaka Comparative biochemistry and physiology. Part D, Genomics & proteomics The yellow drum (Nibea albiflora) is an economically important maricultured fish in China, but the aquaculture of this species is severely affected by overwinter mortality associated with cold stress. Characterization of the molecular mechanisms underlying the susceptibility of the yellow drum to cold might increase our understanding of how this fish adapts to environmental challenges. Here, the transcriptional response of the yellow drum to cold stress (7.5 °C) was investigated with RNA-Seq analysis. We compared brain and muscle transcriptomes among cold-tolerant (Tol) fish that survived the cold treatment, cold-sensitive (Sen) fish that were killed by the cold treatment, and control (Con) fish that were not subjected to cold. Our analysis recovered 233,245 unigenes. The genes (DEGs) differentially expressed in the brain and muscle of the Tol versus Con group, the Sen versus Con group, and the Tol versus Sen group had tissue-specific expression patterns. Gene ontology, enrichment, and pathway analyses indicated the most highly enriched pathways in the DEGs were signaling molecules and interaction, signal transduction, carbohydrate metabolism, lipid metabolism, digestive system, and endocrine system pathways. These pathways were all associated with biological functions relevant to cold adaptation in the yellow drum, including transduction of stress signals, energy metabolism, and stress-induced cell membrane changes. We identified genes likely to be involved in cold-susceptibility and -tolerance as those differentially expressed in the Tol group as compared to the Sen group. Further investigation and characterization of these candidate genes might improve our understanding of the mechanisms underlying cold adaptation in the yellow drum. 10.1016/j.cbd.2018.07.003

Climate change impacts on fish reproduction are mediated at multiple levels of the brain-pituitary-gonad axis. Servili Arianna,Canario Adelino V M,Mouchel Olivier,Muñoz-Cueto José Antonio General and comparative endocrinology Anthropogenic emissions of carbon dioxide in the atmosphere have generated rapid variations in atmospheric composition which drives major climate changes. Climate change related effects include changes in physico-chemical proprieties of sea and freshwater, such as variations in water temperature, salinity, pH/pCO and oxygen content, which can impact fish critical physiological functions including reproduction. In this context, the main aim of the present review is to discuss how climate change related effects (variation in water temperature and salinity, increases in duration and frequency of hypoxia events, water acidification) would impact reproduction by affecting the neuroendocrine axis (brain-pituitary-gonad axis). Variations in temperature and photoperiod regimes are known to strongly affect sex differentiation and the timing and phenology of spawning period in several fish species. Temperature mainly acts at the level of gonad by interfering with steroidogenesis, (notably on gonadal aromatase activity) and gametogenesis. Temperature is also directly involved in the quality of released gametes and embryos development. Changes in salinity or water acidification are especially associated with reduction of sperm quality and reproductive output. Hypoxia events are able to interact with gonad steroidogenesis by acting on the steroids precursor cholesterol availability or directly on aromatase action, with an impact on the quality of gametes and reproductive success. Climate change related effects on water parameters likely influence also the reproductive behavior of fish. Although the precise mechanisms underlying the regulation of these effects are not always understood, in this review we discuss different hypothesis and propose future research perspectives. 10.1016/j.ygcen.2020.113439