Varriale Annalisa, Bernardi Giorgio
Laboratory of Molecular Evolution, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy.
Gene. 2006 Dec 30;385:122-7. doi: 10.1016/j.gene.2006.05.034. Epub 2006 Aug 23.
Very recent investigations have provided evidence for a higher DNA methylation level in polar and sub-antarctic fishes compared to temperate/tropical fishes, the latter being in turn higher than the DNA methylation level of warm-blooded vertebrates. These results confirm and extend the finding [Jabbari, K., Cacciò, S., Pais de Barros, J.P., Desgres, J., Bernardi G., 1997. Evolutionary changes in CpG and methylation levels in the genome of vertebrates. Gene 205, 109-118] that DNA methylation level of vertebrates is inversely related to body temperature. Here we studied the methylation level of reptilian genomes. The species previously analyzed exhibited methylation levels closer to those of mammals and birds rather than to those of fishes and amphibians. The sample was, however, too small to reach a final conclusion. Here we used Reversed-Phase-High-Performance Liquid Chromatography (RP-HPLC) to analyze the DNA methylation levels of 43 reptiles representing three out of four orders and 20 families. Such analysis has shown that snakes and lizards exhibit methylation levels covering the whole range comprised between those of temperate/tropical fish and mammals, while turtles, and, more so, crocodiles are close to mammals. We discuss some ecological and physiological data that explain these results.
最近的研究表明，与温带/热带鱼类相比，极地和亚南极鱼类的DNA甲基化水平更高，而温带/热带鱼类的DNA甲基化水平又高于温血脊椎动物。这些结果证实并扩展了[Jabbari, K., Cacciò, S., Pais de Barros, J.P., Desgres, J., Bernardi G., 1997.脊椎动物基因组中CpG和甲基化水平的进化变化。基因205, 109 - 118]的发现，即脊椎动物的DNA甲基化水平与体温呈负相关。在此，我们研究了爬行动物基因组的甲基化水平。之前分析的物种显示出的甲基化水平更接近哺乳动物和鸟类，而不是鱼类和两栖动物。然而，样本量太小，无法得出最终结论。在此，我们使用反相高效液相色谱法（RP - HPLC）分析了代表四个目中三个目和20个科的43种爬行动物的DNA甲基化水平。这种分析表明，蛇和蜥蜴的甲基化水平涵盖了温带/热带鱼类和哺乳动物之间的整个范围，而龟类，尤其是鳄鱼，接近哺乳动物。我们讨论了一些解释这些结果的生态和生理数据。
