Hooper Sean D, Berg Otto G
Department of Molecular Evolution, Uppsala University, Norbyvagen 18C, SE-75236 Uppsala, Sweden.
Genome Biol. 2003;4(8):R48. doi: 10.1186/gb-2003-4-8-r48. Epub 2003 Jul 11.
Recent developments in the understanding of paralogous evolution have prompted a focus not only on obviously advantageous genes, but also on genes that can be considered to have a weak or sporadic impact on the survival of the organism. Here we examine the duplicative behavior of a category of genes that can be considered to be mostly transient in the genome, namely laterally transferred genes. Using both a compositional method and a gene-tree approach, we identify a number of proposed laterally transferred genes and study their nucleotide composition and frequency of duplication.
It is found that duplications are significantly overrepresented among potential laterally transferred genes compared to the indigenous ones. Furthermore, the GC3 distribution of potential laterally transferred genes was found to be largely uniform in some genomes, suggesting an import from a broad range of donors.
The results are discussed not in a context of strongly optimized established genes, but rather of genes with weak or ancillary functions. The importance of duplication may therefore depend on the variability and availability of weak genes for which novel functions may be discovered. Therefore, lateral transfer may accelerate the evolutionary process of duplication by bringing foreign genes that have mainly weak or no function into the genome.
对旁系同源进化理解的最新进展不仅促使人们关注明显有利的基因，还关注那些被认为对生物体生存有微弱或偶发影响的基因。在此，我们研究了一类在基因组中大多被认为是短暂存在的基因，即横向转移基因的复制行为。我们使用组成方法和基因树方法，鉴定了一些假定的横向转移基因，并研究了它们的核苷酸组成和复制频率。
发现与原生基因相比，潜在横向转移基因中的重复现象明显过多。此外，发现在某些基因组中，潜在横向转移基因的GC3分布在很大程度上是均匀的，这表明它们是从广泛的供体中导入的。
我们不是在已充分优化的既定基因的背景下讨论这些结果，而是在具有微弱或辅助功能的基因的背景下进行讨论。因此，复制的重要性可能取决于那些可能发现新功能的弱基因的变异性和可用性。因此，横向转移可能通过将主要具有微弱功能或无功能的外源基因引入基因组来加速复制的进化过程。
