Tine Mbaye, de Lorgeril Julien, D'Cotta Hélèna, Pepey Elodie, Bonhomme François, Baroiller Jean François, Durand Jean-Dominique
Biologie Intégrative ISEM CNRS-UMR 5554 (Université Montpellier II), Station Méditerranéenne de l'Environnement Littoral, 1 quai de la Daurade, Sète 34200, France; UR070 (IRD), route des hydrocarbures, BP 1386, 18524 Dakar, Sénégal.
Mar Genomics. 2008 Jun;1(2):37-46. doi: 10.1016/j.margen.2008.06.001. Epub 2008 Jul 29.
Sarotherodon melanotheron is one of the most euryhaline teleosts able to withstand variations in environmental salinity ranging from freshwater (FW) to 130‰ hyper-saline waters (HSW). Although significant progress has been made in exploring the cellular and molecular changes that accompany salinity adaptation in teleosts, little is known about the effects of long-term acclimation to HSW. We sought to identify in this tilapia species the genes whose transcription is induced by long-term acclimation either to HSW or FW. Two subtractive cDNA libraries were made from gills of fish acclimated for 45 days to either condition, with 320 partial cDNA sequences encoding proteins potentially involved in the response to the two salinity extremes. The ESTs comparisons with genomic databases allowed putative functions to be attributed to 197 of these genes. The suppression subtractive hybridisation (SSH) results were validated by Real-time PCR for 13 candidate genes having presumably a role in osmoregulation, supplemented by Na(+), K(+)-ATPase α-subunit and carbonic anhydrase, two genes known to be implicated in this function. In fish acclimated to both salinity extremes, the functional category of cellular process was the predominant one, which may indicate high cellular turnover rates in FW and HSW-adapted fish. The acclimation to FW and HSW also appeared to trigger the expression of genes involved in transport activity, biological regulation and metabolic processes, at a higher level in fish acclimated to HSW, suggesting higher metabolic activity in this situation. These results are a first step towards the identification of key molecular processes involved in the fish acclimation to extreme salinities.
黑罗非鱼是最广盐性的硬骨鱼之一，能够耐受从淡水（FW）到130‰高盐水（HSW）的环境盐度变化。尽管在探索硬骨鱼盐度适应过程中伴随的细胞和分子变化方面已经取得了显著进展，但对于长期适应高盐水的影响却知之甚少。我们试图在这种罗非鱼物种中鉴定出那些因长期适应高盐水或淡水而被诱导转录的基因。从分别适应这两种环境45天的鱼的鳃中构建了两个消减cDNA文库，其中有320个部分cDNA序列编码可能参与应对两种极端盐度反应的蛋白质。通过与基因组数据库比较ESTs，可将假定功能赋予其中197个基因。通过实时PCR对13个推测在渗透压调节中起作用的候选基因的抑制消减杂交（SSH）结果进行了验证，并补充了已知参与该功能的两个基因——Na(+)，K(+)-ATP酶α亚基和碳酸酐酶。在适应两种极端盐度的鱼中，细胞过程功能类别占主导地位，这可能表明适应淡水和高盐水的鱼具有较高的细胞更新率。适应淡水和高盐水似乎也会触发参与转运活性、生物调节和代谢过程的基因表达，在适应高盐水的鱼中表达水平更高，这表明在这种情况下代谢活性更高。这些结果是朝着鉴定鱼类适应极端盐度所涉及的关键分子过程迈出的第一步。
