Hara T, Hara R
J Gen Physiol. 1980 Jan;75(1):1-19. doi: 10.1085/jgp.75.1.1.
The deep-sea squid, Todarodes pacificus, possesses well-developed parolfactory vesicles as extraocular photoreceptors connected with the brain. The ventral set of vesicles forms a thread approximately 3mm long and looks orange owing to photopigments. The vesicle mainly consists of receptor cells, each of which is similar in structure to the visual cell, carrying rhabdomeres in the distal process and lamellated myeloid bodies in the proximal part. Recently we noticed that a crude extract of the vesicles is capable of isomerizing retinal from all-trans to the 11-cis form in the light, and confirmed that the vesicles in fact contained retinochrome in addition to rhodopsin. This is the first time that retinochrome has been detected in any place other than ocular tissues. The optical and chemical nature of these photopigments is the same as that we have observed in the Todarodes retina. Quantitative extractions have shown that the total yield of photopigments is approximately 0.0006 in absorbance at lambda max (light path, 10 mm) per milliliter per thread of vesicles, and that the amount of retinochrome in the vesicles is roughly equivalent to that of rhodopsin. Whereas rhodopsin is located in the rhabdomal membranes, retinochrome is probably associated with lamellated structures and their derivatives in the cytoplasm. In the parolfactory vesicles, retinochrome may also cooperate with rhodopsin in the same way as has been discussed for retinal photoreception.
深海鱿鱼太平洋褶柔鱼拥有发达的副嗅觉囊，作为与大脑相连的眼外光感受器。腹侧的那组囊形成一条约3毫米长的细丝，由于含有光色素而呈橙色。该囊主要由受体细胞组成，每个受体细胞的结构与视觉细胞相似，在远端突起中带有视杆，在近端部分带有层状髓样体。最近我们注意到，该囊的粗提物能够在光照下将视黄醛从全反式异构化为11-顺式，并证实该囊除了含有视紫红质外，实际上还含有视黄醛色素。这是首次在眼组织以外的任何地方检测到视黄醛色素。这些光色素的光学和化学性质与我们在太平洋褶柔鱼视网膜中观察到的相同。定量提取表明，每毫升每细丝囊的光色素在最大吸收波长（光路10毫米）处的总吸光度产量约为0.0006，并且囊中的视黄醛色素量大致相当于视紫红质的量。视紫红质位于视杆膜中，而视黄醛色素可能与细胞质中的层状结构及其衍生物相关。在副嗅觉囊中，视黄醛色素也可能与视紫红质以与视网膜光接收中所讨论的相同方式协同作用。
