Knau H, Kremers J, Schmidt H-J, Wolf S, Wissinger B, Sharpe L T
University Eye Hospital, FEO, 72076, Tübingen, Germany.
Vision Res. 2002 Jul;42(15):1888-96. doi: 10.1016/s0042-6989(02)00054-8.
Molecular genetic studies demonstrate that the human cone opsin gene array on the q-arm of the X-chromosome typically consists of one long-wave-sensitive (L) cone opsin gene and from one to several middle-wave-sensitive (M) cone opsin genes. Although the presence of the single L-cone opsin gene and at least one M-cone opsin gene is essential for normal red-green colour discrimination, the function of the additional M-cone opsin genes is still unclear. To investigate whether any variations in phenotype correlate with differences in the number of M-cone opsin genes, we selected 13 normal trichromat males, for whom four independent molecular techniques have exactly determined their number of M-cone opsin genes, ranging from one to four. Their phenotype was characterized by estimating their foveal L- to M-cone ratio from heterochromatic flicker photometric (HFP) thresholds, by measuring the wavelength corresponding to their 'unique yellow', and by determining their L- and M-cone modulation thresholds (CMTs). No correlation was found between these psychophysical measures and the number of M-cone opsin genes. Although, we found a reasonably good correlation between the L/M-cone ratios based on HFP and on CMT, we did not find any correlation between the estimated L/M-cone ratios and the settings of 'unique yellow'. Our results accord with previous molecular genetic studies that suggest that only the first two genes in the X-linked opsin gene array are expressed.
分子遗传学研究表明，位于X染色体q臂上的人类视锥细胞视蛋白基因阵列通常由一个长波敏感（L）视锥细胞视蛋白基因和一至几个中波敏感（M）视锥细胞视蛋白基因组成。虽然单个L视锥细胞视蛋白基因和至少一个M视锥细胞视蛋白基因的存在对于正常的红绿色觉辨别至关重要，但额外的M视锥细胞视蛋白基因的功能仍不清楚。为了研究表型的任何变化是否与M视锥细胞视蛋白基因数量的差异相关，我们选择了13名正常三色觉男性，通过四种独立的分子技术准确确定了他们的M视锥细胞视蛋白基因数量，范围从1到4个。通过从异色闪烁光度法（HFP）阈值估计他们的中央凹L视锥细胞与M视锥细胞的比例、测量与他们的“独特黄色”相对应的波长以及确定他们的L视锥细胞和M视锥细胞调制阈值（CMT）来表征他们的表型。在这些心理物理学测量与M视锥细胞视蛋白基因数量之间未发现相关性。虽然我们发现基于HFP和CMT的L/M视锥细胞比例之间有相当好的相关性，但我们没有发现估计的L/M视锥细胞比例与“独特黄色”的设置之间有任何相关性。我们的结果与先前的分子遗传学研究一致，这些研究表明X连锁视蛋白基因阵列中只有前两个基因表达。
