Hopkins Marine Station, Stanford University, Oceanview Blvd., Pacific Grove, CA 93950, USA.
Mol Ecol. 2011 Feb;20(3):517-29. doi: 10.1111/j.1365-294X.2010.04973.x. Epub 2010 Dec 28.
The invasive marine mussel Mytilus galloprovincialis has displaced the native congener Mytilus trossulus from central and southern California, but the native species remains dominant at more northerly sites that have high levels of freshwater input. To determine the extent to which interspecific differences in physiological tolerance to low salinity might explain limits to the invasive species' biogeography, we used an oligonucleotide microarray to compare the transcriptional responses of these two species to an acute decrease in salinity. Among 6777 genes on the microarray, 117 genes showed significant changes that were similar between species, and 12 genes showed significant species-specific responses to salinity stress. Osmoregulation and cell cycle control were important aspects of the shared transcriptomic response to salinity stress, whereas the genes with species-specific expression patterns were involved in mRNA splicing, polyamine synthesis, exocytosis, translation, cell adhesion, and cell signalling. Forty-five genes that changed expression significantly during salinity stress also changed expression during heat stress, but the direction of change in expression was typically opposite for the two forms of stress. These results (i) provide insights into the role of changes in gene expression in establishing physiological tolerance to acute decreases in salinity, and (ii) indicate that transcriptomic differences between M. galloprovincialis and M. trossulus in response to salinity stress are subtle and involve only a minor fraction of the overall suite of gene regulatory responses.
入侵性海洋贻贝厚壳贻贝已经取代了加利福尼亚中部和南部的本地贻贝，但在淡水输入量较高的更北部地区，本地物种仍然占据主导地位。为了确定种间对低盐度生理耐受性差异在多大程度上可以解释入侵物种生物地理学的限制，我们使用寡核苷酸微阵列比较了这两个物种对盐度急性下降的转录反应。在微阵列上的 6777 个基因中，有 117 个基因的变化在物种间相似，有 12 个基因对盐度胁迫有显著的种特异性反应。渗透调节和细胞周期控制是盐度胁迫下共享转录组反应的重要方面，而具有种特异性表达模式的基因则参与 mRNA 剪接、多胺合成、胞吐作用、翻译、细胞黏附和细胞信号转导。在盐度胁迫期间表达显著变化的 45 个基因在热胁迫期间也表达显著变化，但两种胁迫下表达变化的方向通常相反。这些结果：（i）深入了解了基因表达变化在建立对盐度急性下降的生理耐受性中的作用；（ii）表明厚壳贻贝和 M. trossulus 对盐度胁迫的转录组差异很细微，仅涉及整体基因调控反应的一小部分。
