Laboratoire Génome Populations Interaction Adaptation, UMR CNRS IFREMER 5171, Université de Montpellier 2, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
Comp Biochem Physiol Part D Genomics Proteomics. 2007 Mar;2(1):74-83. doi: 10.1016/j.cbd.2006.12.002. Epub 2006 Dec 13.
Although prolactin has been demonstrated to be the main hormone involved in adaptation to dilute media in several freshwater teleosts, few studies have been conducted in marine teleosts. In the Mediterranean, the sea bass Dicentrarchus labrax inhabits environments ranging from the open sea to coastal lagoons, where salinity varies greatly. We characterised the prolactin (prl) gene and analysed its expression in two organs (gill and intestine) in D. labrax acclimated to either freshwater or seawater. A 2819 bp long sequence encompassing the prl gene and a part (282 bp) of the promoter were identified, and these comprised 5 coding exons separated by 4 introns. Prolactin was similarly expressed in fresh- and seawater adapted fish, although expression in gills was significantly greater than in the intestine. Nonetheless, individuals unable to successfully regulate osmotic balance in freshwater presented overall low expression rates. Results are discussed according to the mechanism of sea bass adaptation in the wild and to their life cycle between open sea and lagoons. Finally, a phylogenetic analysis indicated that teleosts are not branched according to their life-history features (e.g. seawater vs. freshwater habitats), and no signature of positive selection was detected across the phylogeny of the prl gene in teleosts.
虽然催乳素已被证明是几种淡水硬骨鱼适应稀释介质的主要激素，但在海洋硬骨鱼中进行的研究较少。在地中海，鲈鱼（Dicentrarchus labrax）栖息于从开阔海域到沿海泻湖的各种环境中，盐度变化很大。我们对鲈鱼催乳素（prl）基因进行了特征描述，并分析了其在适应淡水或海水的两个器官（鳃和肠）中的表达。鉴定出了一个 2819bp 长的序列，包含 prl 基因和启动子的一部分（282bp），这些序列由 5 个编码外显子和 4 个内含子隔开。催乳素在适应淡水和海水的鱼中表达相似，尽管在鳃中的表达显著高于肠。然而，在淡水中无法成功调节渗透压平衡的个体总体表达率较低。根据鲈鱼在野外的适应机制及其在开阔海域和泻湖之间的生命周期，对结果进行了讨论。最后，系统发育分析表明，硬骨鱼不是根据其生活史特征（例如海水与淡水栖息地）分支的，并且在硬骨鱼催乳素基因的系统发育中没有检测到正选择的迹象。
