Stenico M, Lloyd A T, Sharp P M
Department of Genetics, Trinity College, Dublin, Ireland.
Nucleic Acids Res. 1994 Jul 11;22(13):2437-46. doi: 10.1093/nar/22.13.2437.
Synonymous codon usage varies considerably among Caenorhabditis elegans genes. Multivariate statistical analyses reveal a single major trend among genes. At one end of the trend lie genes with relatively unbiased codon usage. These genes appear to be lowly expressed, and their patterns of codon usage are consistent with mutational biases influenced by the neighbouring nucleotide. At the other extreme lie genes with extremely biased codon usage. These genes appear to be highly expressed, and their codon usage seems to have been shaped by selection favouring a limited number of translationally optimal codons. Thus, the frequency of these optimal codons in a gene appears to be correlated with the level of gene expression, and may be a useful indicator in the case of genes (or open reading frames) whose expression levels (or even function) are unknown. A second, relatively minor trend among genes is correlated with the frequency of G at synonymously variable sites. It is not yet clear whether this trend reflects variation in base composition (or mutational biases) among regions of the C.elegans genome, or some other factor. Sequence divergence between C.elegans and C.briggsae has also been studied.
秀丽隐杆线虫基因间同义密码子的使用差异很大。多变量统计分析揭示了基因间的一个主要趋势。在该趋势的一端是密码子使用相对无偏差的基因。这些基因似乎表达水平较低，其密码子使用模式与受相邻核苷酸影响的突变偏差一致。在另一个极端是密码子使用极度有偏差的基因。这些基因似乎高度表达，其密码子使用似乎是由对有限数量的翻译最优密码子的选择所塑造的。因此，一个基因中这些最优密码子的频率似乎与基因表达水平相关，对于那些表达水平（甚至功能）未知的基因（或开放阅读框）而言，这可能是一个有用的指标。基因间第二个相对较小的趋势与同义可变位点处G的频率相关。目前尚不清楚这种趋势是反映了秀丽隐杆线虫基因组区域间碱基组成的差异（或突变偏差），还是其他一些因素。也对秀丽隐杆线虫和布氏秀丽线虫之间的序列差异进行了研究。
