Baur P S
J Neurobiol. 1977 Jan;8(1):19-42. doi: 10.1002/neu.480080103.
The ultrastructure, absorbance, and elemental content of lipochondria present in the cytoplasm of Aplysia giant neurons have been investigated before and after 30-1,200 sec doses of white light at intensities which produce saturated light responses. The effects of exposure to the calcium ionophore A-23187 and to EGTA were also examined. The lipochondria of nonilluminated neurons are membrane-bound, and contain lipids, protein, Na, K, Mg Ca, Si, Cl, Br, P, and a pigment which is probably beta-carotene. The cytoplasm appeared to have little pigment. When neurons were illuminated for 20 min, 60-70% of the lipochondria showed marked ultrastructural alterations, the most notable being the appearance of membranous material. Earlier changes which occur after 30 sec of illumination include the appearance of paracrystalline arrays and mottling. Less than 10% of lipochondria in nonilluminated neurons have a similar appearance. These effects were greatly enhanced in illuminated neurons exposed to the calcium ionophore or EGTA. In nonilluminated neurons, the ionophore also produced ultrastructural changes. In frozen specimens, the calcium content of the most electron dense lipochondria of illuminated neurons was reduced. Other elements which were counted were also reduced. The lipochondria are the main intracellular site of photopigment. They may also act as an intracellular source for calcium which, as the accompanying paper indicated, may mediate phototransduction in Aplysia neurons.
对海兔巨型神经元细胞质中存在的脂质体在30至1200秒剂量的白光照射前后的超微结构、吸光度和元素含量进行了研究，照射强度为产生饱和光反应的强度。还研究了暴露于钙离子载体A - 23187和乙二醇双四乙酸（EGTA）的影响。未受光照的神经元的脂质体是有膜包被的，含有脂质、蛋白质、钠、钾、镁、钙、硅、氯、溴、磷，以及一种可能是β - 胡萝卜素的色素。细胞质中似乎色素很少。当神经元被光照20分钟时，60 - 70%的脂质体显示出明显的超微结构改变，最显著的是出现膜状物质。光照30秒后出现的早期变化包括准晶体阵列的出现和斑点。未受光照的神经元中不到10%的脂质体有类似外观。在暴露于钙离子载体或EGTA的受光照神经元中，这些影响大大增强。在未受光照的神经元中，离子载体也产生超微结构变化。在冷冻标本中，受光照神经元中电子密度最高的脂质体的钙含量降低。其他被计数的元素也减少了。脂质体是光色素的主要细胞内位点。它们也可能作为细胞内钙源，正如随附论文所指出的，钙可能介导海兔神经元中的光转导。
