Lawrence J G, Hendrix R W, Casjens S
Pittsburgh Bacteriophage Institute and Dept of Biological Sciences, University of Pittsburgh, PA 15260, USA. jlawrenc+@pitt.edu
Trends Microbiol. 2001 Nov;9(11):535-40. doi: 10.1016/s0966-842x(01)02198-9.
Most bacterial genomes have very few pseudogenes; notable exceptions include the genomes of the intracellular parasites Rickettsia prowazekii and Mycobacterium leprae. As DNA can be introduced into microbial genomes in many ways, the compact nature of these genomes suggests that the rate of DNA influx is balanced by the rate of DNA deletion. We propose that the influx of dangerous genetic elements such as transposons and bacteriophages selects for the maintenance of relatively high deletion rates in most bacteria; the sheltered lifestyle of intracellular parasites removes this threat, leading to reduced deletion rates and larger pseudogene loads.
大多数细菌基因组中的假基因很少；值得注意的例外包括细胞内寄生虫普氏立克次氏体和麻风分枝杆菌的基因组。由于DNA可以通过多种方式引入微生物基因组，这些基因组的紧凑性质表明DNA流入速率与DNA缺失速率相平衡。我们提出，转座子和噬菌体等危险遗传元件的流入促使大多数细菌维持相对较高的缺失率；细胞内寄生虫的隐蔽生活方式消除了这种威胁，导致缺失率降低和假基因负荷增加。
