Govardovskii V I, Fyhrquist N, Reuter T, Kuzmin D G, Donner K
lnstitute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg.
Vis Neurosci. 2000 Jul-Aug;17(4):509-28. doi: 10.1017/s0952523800174036.
Absorbance spectra were recorded by microspectrophotometry from 39 different rod and cone types representing amphibians. reptiles, and fishes, with A1- or A2-based visual pigments and lambdamax ranging from 357 to 620 nm. The purpose was to investigate accuracy limits of putative universal templates for visual pigment absorbance spectra, and if possible to amend the templates to overcome the limitations. It was found that (1) the absorbance spectrum of frog rhodopsin extract very precisely parallels that of rod outer segments from the same individual, with only a slight hypsochromic shift in lambdamax, hence templates based on extracts are valid for absorbance in situ: (2) a template based on the bovine rhodopsin extract data of Partridge and De Grip (1991) describes the absorbance of amphibian rod outer segments excellently, contrary to recent electrophysiological results; (3) the lambdamax/lambda invariance of spectral shape fails for A1 pigments with small lambdamax and for A2 pigments with large lambdamax, but the deviations are systematic and can be readily incorporated into, for example, the Lamb (1995) template. We thus propose modified templates for the main "alpha-band" of A1 and A2 pigments and show that these describe both absorbance and spectral sensitivities of photoreceptors over the whole range of lambdamax. Subtraction of the alpha-band from the full absorbance spectrum leaves a "beta-band" described by a lambdamax-dependent Gaussian. We conclude that the idea of universal templates (one for A1- and one for A2-based visual pigments) remains valid and useful at the present level of accuracy of data on photoreceptor absorbance and sensitivity. The sum of our expressions for the alpha- and beta-band gives a good description for visual pigment spectra with lambdamax > 350 nm.
通过显微分光光度法记录了代表两栖动物、爬行动物和鱼类的39种不同视杆和视锥类型的吸光光谱，这些视杆和视锥具有基于A1或A2的视觉色素，其最大吸收波长范围为357至620纳米。目的是研究视觉色素吸光光谱假定通用模板的精度极限，并尽可能修正模板以克服这些限制。研究发现：（1）青蛙视紫红质提取物的吸光光谱与来自同一个体的视杆外段的吸光光谱非常精确地平行，仅最大吸收波长有轻微的紫移，因此基于提取物的模板对于原位吸光是有效的；（2）基于Partridge和De Grip（1991）的牛视紫红质提取物数据的模板很好地描述了两栖动物视杆外段的吸光情况，这与最近的电生理结果相反；（3）对于最大吸收波长较小的A1色素和最大吸收波长较大的A2色素，光谱形状的最大吸收波长/等波长不变性不成立，但偏差是系统性的，并且可以很容易地纳入例如Lamb（1995）模板中。因此，我们提出了针对A1和A2色素主要“α带”的修正模板，并表明这些模板描述了整个最大吸收波长范围内光感受器的吸光和光谱敏感性。从全吸光光谱中减去α带后留下一个由最大吸收波长依赖的高斯函数描述的“β带”。我们得出结论，在目前光感受器吸光和敏感性数据的精度水平上，通用模板（一个用于基于A1的视觉色素，一个用于基于A2的视觉色素）的概念仍然有效且有用。我们对α带和β带的表达式之和对最大吸收波长>350纳米的视觉色素光谱给出了很好的描述。
