Makapedua Daisy Monica, Barucca Marco, Forconi Mariko, Antonucci Niki, Bizzaro Davide, Amici Adolfo, Carradori Maria Rita, Olmo Ettore, Canapa Adriana
Dipartimento di Biochimica, Biologia e Genetica, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
Mar Genomics. 2011 Sep;4(3):167-72. doi: 10.1016/j.margen.2011.04.001. Epub 2011 Jul 8.
The living fossil Latimeria menadoensis is important to understand sarcopterygian evolution. To gain further insights into this fish species we studied its genome size, GC% and 5mC level. The genome size and the GC% of the Indonesian coelacanth seem to be very similar to those of the African coelacanth. Moreover the GC%, the CpG frequency and the 5mC level of L. menadoensis are more similar to those of fish and amphibians than to those of mammals, birds and reptiles and this is in line with the hypothesis that two different DNA methylation and CpG shortage equilibria arose during vertebrate evolution. Our results suggest that the genome of L. menadoensis has remained unchanged for several million years, maybe since the origin of the lineage which from lobe-finned fish led to tetrapods. These data fit a conservative evolutionary landscape and suggest that the genome of the extant crossopterygians may be a sort of evolutionarily frozen genome.
活化石曼氏空棘鱼对于理解肉鳍鱼的进化具有重要意义。为了进一步深入了解这种鱼类，我们研究了它的基因组大小、GC含量和5-甲基胞嘧啶水平。印度尼西亚腔棘鱼的基因组大小和GC含量似乎与非洲腔棘鱼非常相似。此外，曼氏空棘鱼的GC含量、CpG频率和5-甲基胞嘧啶水平与鱼类和两栖动物的更为相似，而与哺乳动物、鸟类和爬行动物的不同，这与脊椎动物进化过程中出现两种不同的DNA甲基化和CpG短缺平衡的假说相符。我们的研究结果表明，曼氏空棘鱼的基因组在数百万年里一直保持不变，可能自叶鳍鱼类演化出四足动物的谱系起源之时起就未曾改变。这些数据符合保守的进化图景，并表明现存总鳍鱼类的基因组可能是一种进化上冻结的基因组。
