Katagiri Nobuko, Suzuki Tatsuo, Shimatani Yuichi, Katagiri Yasuo
Medical Research Institute, Tokyo Women's Medical University, Tokyo, Japan.
Zoolog Sci. 2002 Nov;19(11):1231-40. doi: 10.2108/zsj.19.1231.
Onchidium possesses stalk eye (SE) and dorsal eye (DE) which comprise part of a unique multiple photoreceptive system. The retina of SE consists of rhabdomeric-type visual cells, whereas the DE contains two types of photoreceptor cells; ciliary-type cells in the retina and rhabdomeric-type cells in the lens. High-performance liquid chromatography (HPLC) analyses revealed the presence of 11-cis-retinal as well as all-trans-retinal in both eyes. The amount of retinal of one DE (0.17 pmol) is far less than that in one SE (0.41 pmol) in the dark-adapted Onchidium. In the dark-adapted SE, the amount of all-trans-retinal was higher than that of 11-cis-retinal. This finding is consistent with the presence of photic vesicles, including retinochrome, in rhabdomeric-type visual cells. In contrast, a higher amount of 11-cis-retinal than all-trans-retinal was present in dark-adapted DE, although this was decreased in light-adapted DE. Upon UV irradiation following treatment with sodium borohydride (NaBH(4)), the fluorescence (derived from retinochrome) was observed in the somatic layer of SE. Additional fluorescence (due to rhodopsin) was observed in the villous layer upon treatment with NaBH(4) after denaturation. However, only weak, obscure fluorescence of retinyl proteins was observed in the DE, not in a specific but an indefinite area on treatment with NaBH4 with or without denaturation. With fluorescence histochemistry, the localization of rhodopsin and retinochrome was confirmed at specific regions in the retina of the SE, whereas no distinct localization of these photopigments in DE was demonstrated. The amount of retinal to detect the fluorescence may be too low in the DE, or photopigments of DE may differ in chemical nature from those of SE.
石磺拥有柄眼（SE）和背眼（DE），它们构成了独特的多重感光系统的一部分。柄眼的视网膜由视杆型视觉细胞组成，而背眼包含两种类型的光感受器细胞；视网膜中的睫状型细胞和晶状体中的视杆型细胞。高效液相色谱（HPLC）分析显示，两只眼睛中均存在11-顺式视黄醛以及全反式视黄醛。在暗适应的石磺中，一个背眼的视黄醛含量（0.17皮摩尔）远低于一个柄眼的视黄醛含量（0.41皮摩尔）。在暗适应的柄眼中，全反式视黄醛的含量高于11-顺式视黄醛。这一发现与视杆型视觉细胞中存在包括视紫红质在内的光小泡一致。相比之下，暗适应的背眼中11-顺式视黄醛的含量高于全反式视黄醛，尽管在光适应的背眼中这种情况有所减少。在用硼氢化钠（NaBH₄）处理后进行紫外线照射时，在柄眼的体细胞层中观察到了荧光（源自视紫红质）。变性后用NaBH₄处理时，在绒毛层中观察到了额外的荧光（由于视紫红质）。然而，在用NaBH₄处理（无论是否变性）后，在背眼中仅观察到了微弱、模糊的视黄醛蛋白荧光，且不是在特定区域，而是在不确定区域。通过荧光组织化学，视紫红质和视紫红质在柄眼视网膜的特定区域的定位得到了证实，而在背眼中未显示出这些光色素的明显定位。背眼中检测荧光所需的视黄醛含量可能过低，或者背眼的光色素在化学性质上可能与柄眼的不同。
