Tiersch T R, Wachtel S S
Department of Biology, Memphis State University, Tennessee.
J Hered. 1991 Sep-Oct;82(5):363-8. doi: 10.1093/oxfordjournals.jhered.a111105.
We measured genome size (nuclear DNA content) by fluorescence flow cytometry in 55 species of birds representing 12 different orders. Similar studies were performed in approximately 100 species by laboratories using absorption cytophotometry of Feulgen-stained nuclei. Although there have been apparent discrepancies in the assigned values for the species used as a reference, the values obtained in the different laboratories are generally in agreement. When the data are standardized in relation to a diploid (2C) value of 2.5 picograms (pg) of DNA for the domestic chicken (Gallus gallus domesticus), the mean for DNA content in 135 species representing 17 orders is 2.82 +/- 0.33 (SD) pg with a range of 2.0-3.8 pg. Thus the genome size of birds is the most conservative of any vertebrate class and, all values considered, is smaller and more uniform in size than previous estimates would indicate. This could be explained by a previously unexplored hypothesis: that the genome of birds has evolved from a small ancestral genome that was reduced before emergence of the protoavian.
我们通过荧光流式细胞术测量了代表12个不同目鸟类的55个物种的基因组大小（核DNA含量）。其他实验室使用福尔根染色细胞核的吸收细胞光度法对大约100个物种进行了类似研究。尽管用作参考的物种的指定值存在明显差异，但不同实验室获得的值总体上是一致的。当数据相对于家鸡（Gallus gallus domesticus）二倍体（2C）值2.5皮克（pg）的DNA进行标准化时，代表17个目的135个物种的DNA含量平均值为2.82±0.33（标准差）pg，范围为2.0 - 3.8 pg。因此，鸟类的基因组大小是所有脊椎动物类群中最保守的，综合所有数值来看，其基因组比之前的估计更小且大小更均匀。这可以用一个之前未被探索的假说来解释：鸟类的基因组是从一个在原鸟类出现之前就已缩小的小祖先基因组进化而来的。
