Current Biology:科学家成功恢复洞穴鱼视力
通过对没有视力的洞穴鱼进行杂交实验，最近科学家成功地恢复了一些洞穴鱼的视力。
洞穴鱼的形成大约在更新世中期，它们的祖先生活在地表，而且是有视力的。已有的研究表明，洞穴鱼视力的退化至少经历了三次独立的进化事件。来自纽约大学的Richard Borowsky通过对生活在墨西哥东北部的不同的洞穴鱼群体进行杂交实验研究了洞穴鱼的视力恢复情况。结果表明，所有地表鱼和洞穴鱼杂交的子一代都具有完好的视力。但是，洞穴鱼之间杂交的后代中子一代最多只有将近40%的个体视力完好，而子二代中视力完好的个体所占的比例则要低得多。用来自不同地点的洞穴鱼和地表鱼的杂交后代作为亲本杂交的后代中，相距较远的群体之间的后代其视力要远高于由较近的群体间繁殖产生的后代。Richard Borowsky解释说，地理距离较近的群体间具有最近的共同祖先并且享有共同的眼睛位点。洞穴鱼的祖先处于地下没有光的环境中已经有100万年的历史了。因此，主导进化方向的是环境因素，而不是最初的基因类型。
相关论文发表在1月份的《当代生物学》（Current Biology）上。（科学新闻杂志 王保成/编译）
生物谷推荐原始出处：
（Current Biology），Vol 18, R23-R24，Richard Borowsky
Restoring sight in blind cavefish
Richard Borowsky
Summary
Twenty-nine populations of the blind cavefish, Astyanax mexicanus, are known from different caves in North-Eastern Mexico (Figure 1). They evolved from eyed, surface-dwelling forms which only reached the area in the mid-Pleistocene . Quantitative genetic analyses have shown that the evolutionary impairment of eye development — as well as the loss of pigmentation and other cave-related changes — results from mutations at multiple gene sites (‘eye loci’) . Eye loss has evolved independently at least three times and at least some of the eye loci involved differ between the different cave populations . Hybrids between blind cavefish from different caves have larger and better developed eye rudiments than their parents (Figure 2), reflecting these independent origins and complementation. Given the large number of mutations at different loci that have accumulated in these populations, we reasoned that hybridization among independently evolved populations might restore visual function. Here we demonstrate restoration of vision in cavefish whose immediate ancestors were blind and whose separate lineages may not have been exposed to light for the last one million years.
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