Pouchkina-Stantcheva Natalia N, McGee Brian M, Boschetti Chiara, Tolleter Dimitri, Chakrabortee Sohini, Popova Antoaneta V, Meersman Filip, Macherel David, Hincha Dirk K, Tunnacliffe Alan
Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT, UK.
Science. 2007 Oct 12;318(5848):268-71. doi: 10.1126/science.1144363.
Theory suggests it should be difficult for asexual organisms to adapt to a changing environment because genetic diversity can only arise from mutations accumulating within direct antecedents and not through sexual exchange. In an asexual microinvertebrate, the bdelloid rotifer, we have observed a mechanism by which such organisms could acquire the diversity needed for adaptation. Gene copies most likely representing former alleles have diverged in function so that the proteins they encode play complementary roles in survival of dry conditions. One protein prevents desiccation-sensitive enzymes from aggregating during drying, whereas its counterpart does not have this activity, but is able to associate with phospholipid bilayers and is potentially involved in maintenance of membrane integrity. The functional divergence of former alleles observed here suggests that adoption of asexual reproduction could itself be an evolutionary mechanism for the generation of diversity.
理论表明，无性生殖的生物体应该很难适应不断变化的环境，因为基因多样性只能源于在直系祖先中积累的突变，而不是通过有性交换产生。在一种无性的微型无脊椎动物——蛭形轮虫中，我们观察到了一种机制，通过这种机制，此类生物体能够获得适应所需的多样性。很可能代表以前等位基因的基因拷贝在功能上已经发生了分化，因此它们编码的蛋白质在干燥条件下的存活中发挥着互补作用。一种蛋白质可防止对干燥敏感的酶在干燥过程中聚集，而其对应物则没有这种活性，但能够与磷脂双层结合，并可能参与维持膜的完整性。此处观察到的以前等位基因的功能分化表明，采用无性生殖本身可能是一种产生多样性的进化机制。
