Jacobs G H, Neitz M, Neitz J
Department of Psychology, University of California, Santa Barbara 93106, USA.
Proc Biol Sci. 1996 Jun 22;263(1371):705-10. doi: 10.1098/rspb.1996.0105.
Most primates have short-wavelength sensitive (S) cones and one or more types of cone maximally sensitive in the middle to long wavelengths (M/L cones). These multiple cone types provide the basis for colour vision. Earlier experiments established that two species of noctural primate, the owl monkey (Aotus trivirgatus) and the bushbaby (Otolemur crassicaudatus), lack a viable population of S cones. Because the retinas of these species have only a single type of M/L cone, they lack colour vision. Both of these species have an S-cone pigment gene that is highly homologous to the human S-cone pigment gene. Examination of the nucleotide sequences of the S-cone pigment genes reveals that each species has deleterious mutational changes: in comparison to the sequence for the corresponding region of the human gene, exon 4 of the bushbaby S-cone pigment gene has a two nucleotide deletion and a single nucleotide insertion that produces a frame shift and results in the introduction of a stop codon. Exon 1 of the owl monkey S-cone pigment gene likewise contains deletions and insertions that produce a stop codon. The absence of colour vision in both of these nocturnal primates can thus be traced to defects in their S-cone pigment genes.
大多数灵长类动物具有短波敏感（S）视锥细胞和一种或多种在中长波中敏感度最高的视锥细胞类型（M/L视锥细胞）。这些多种视锥细胞类型为色觉提供了基础。早期实验表明，两种夜行性灵长类动物，即夜猴（Aotus trivirgatus）和婴猴（Otolemur crassicaudatus），缺乏存活的S视锥细胞群体。由于这些物种的视网膜只有一种M/L视锥细胞类型，它们缺乏色觉。这两个物种都有一个与人类S视锥色素基因高度同源的S视锥色素基因。对S视锥色素基因的核苷酸序列进行检查发现，每个物种都有有害的突变变化：与人类基因相应区域的序列相比，婴猴S视锥色素基因的外显子4有两个核苷酸缺失和一个单核苷酸插入，这会导致移码并引入一个终止密码子。夜猴S视锥色素基因的外显子1同样包含产生终止密码子的缺失和插入。因此，这两种夜行性灵长类动物缺乏色觉可追溯到它们的S视锥色素基因缺陷。
