Quax-Jeuken Y, Bruisten S, Bloemendal H, de Jong W W, Nevo E
Department of Biochemistry, University of Nijmegen, The Netherlands.
Mol Biol Evol. 1985 Jul;2(4):279-88. doi: 10.1093/oxfordjournals.molbev.a040351.
The mole (Talpa europaea; Insectivora) and the mole rat (Spalax ehrenbergi; Rodentia) both have degenerated eyes as a convergent adaptation to subterranean life. The rudimentary eye lenses of these blind mammals no longer function in a visual process. The crystallin genes, which display a lens-specific expression pattern, were studied in these blind mammals and in related species with normal eyes by hybridizing their genomic DNAs with probes obtained from cDNA clones for alpha A-, alpha B-, and beta Bp-crystallins from calf and gamma 3-crystallin from the rat. For all crystallin genes examined, the hybridization signals of mole and mole rat genomic DNA were comparable, respectively, with those of shrew and of rat and mouse, normal-vision representatives of the orders Insectivora and Rodentia. The expression of the crystallins at the protein level was tested by using antiserum specific for alpha-crystallin in immunofluorescence reactions on lens sections of mole and mole rat eyes and by using antisera against the beta- and gamma-crystallins on sections of the mole eye. All antisera gave positive fluorescence reactions exclusively with lens tissue of these blind mammals, indicating that the crystallins are still normally expressed despite the fact that these lenses have had no function in a visual process in these mammals for at least many million years. These findings apparently imply that some unknown selective advantage has conserved the crystallin genes and their expression after the loss of normal function of the lenses.
鼹鼠（欧洲鼹鼠；食虫目）和鼹形鼠（埃氏鼹形鼠；啮齿目）都有退化的眼睛，这是对地下生活的一种趋同适应。这些失明哺乳动物的残留晶状体不再在视觉过程中发挥作用。通过将它们的基因组DNA与从小牛的αA-、αB-和βBp-晶状体蛋白以及大鼠的γ3-晶状体蛋白的cDNA克隆获得的探针杂交，对这些失明哺乳动物以及相关的具有正常眼睛的物种中显示晶状体特异性表达模式的晶状体蛋白基因进行了研究。对于所有检测的晶状体蛋白基因，鼹鼠和鼹形鼠基因组DNA的杂交信号分别与鼩鼱以及大鼠和小鼠（食虫目和啮齿目具有正常视力的代表物种）的杂交信号相当。通过在鼹鼠和鼹形鼠眼睛的晶状体切片上进行免疫荧光反应，使用对α-晶状体蛋白特异的抗血清，并在鼹鼠眼睛切片上使用针对β-和γ-晶状体蛋白的抗血清，来检测晶状体蛋白在蛋白质水平的表达。所有抗血清仅与这些失明哺乳动物的晶状体组织产生阳性荧光反应，这表明尽管这些晶状体在这些哺乳动物的视觉过程中至少数百万年都没有功能，但晶状体蛋白仍然正常表达。这些发现显然意味着在晶状体失去正常功能后，某种未知的选择优势保留了晶状体蛋白基因及其表达。
