Cyclic metabolism of photoreceptor cells.
Cyclic metabolism of photoreceptor cells.
复制标题
感光细胞的循环代谢。
DOI：
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发表时间：
1978
影响因子：
4.4
通讯作者：
S. Basinger
中科院分区：
文献类型：
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作者：
Joe G. Hollyfield;S. Basinger
这一期的《眼科学与视觉科学》包含三篇关于感光细胞代谢周期性的论文。' 9i 26这个研究领域代表了当今视觉研究最活跃的领域之一。光感受器及其支持组织，色素上皮细胞的研究的速度和范围，已经加速到的程度，更多的新信息外节营业额的控制机制，已获得在过去的2年内比以前获得的十年。这一系列研究的任何年表都必须从拜拉蒂和奥扎莱西对人类色素上皮的早期超微结构研究开始开始。这些作者是第一个正确解释的层状包涵体在这个组织中，现在被称为吞噬体，最初是感光细胞外节的一部分。他们进一步建议，应通过向外节基部添加新形成的膜材料来平衡该材料从外节尖端的分离和吞噬作用。这为Young和Young和Droz的经典放射自显影研究奠定了基础，这些研究坚定地确立了视杆细胞外节膜在整个生命过程中都会更新。当给动物注射放射性氨基酸来标记新合成的蛋白质时，第一个掺入的位点是在光感受器内节内，正如Droz早些时候观察到的那样。这种新合成的蛋白质的大部分然后被运输到外节基部，在那里它被用来形成放射性外节膜盘带。随着这一膜添加过程的继续，放射性条带沿着外节的长度移位到尖端，在那里它作为一包膜盘脱落。然后这些膜碎片被色素上皮吞噬和降解。Hall等人的实验进一步证明，许多新的膜蛋白是视杆视色素视紫红质。这种视杆细胞外节更新的模式在每一种脊椎动物中都能观察到。在这些放射自显影研究中，观察到锥体外节被弥散标记，但从未形成标记盘的离散带。这导致杨提出，锥体外节是通过整个外节中的单个分子的替换而更新的，而不是通过底部的膜组件的杆系统和尖端的膜包的损失。然而，安德森、费舍尔和斯坦伯格对松鼠视网膜中的视锥光感受器的形态学研究以及斯坦伯格、伍德和霍根对人类视网膜中的视锥光感受器的形态学研究21
iis issue of INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE contains three papers dealing with the cyclic nature of photoreceptor cell metabolism.' 9i 26 This field of investigation represents one of the most active areas of vision research today. The speed and range of studies on photoreceptors and their supportive tissue, the pigment epithelium, have accelerated to the degree that more new information on the control mechanisms of outer segment turnover has been obtained within the last 2 years than had formerly been obtained in a decade. Any chronology of this line of investigation must begin with a reference to the early ultrastructural studies of the human pigment epithelium by Bairati and Orzalesi. These authors were the first to interpret correctly the lamellar inclusion bodies within this tissue, now termed phagosomes, as having originally been a part of the photoreceptor outer segments. They further suggested that the detachment and phagocytosis of this material from the outer segment tip should be balanced by the addition of newly formed membrane material to the outer segment base. This set the stage for the classic autoradiographic studies of Young and Young and Droz, which firmly established that the outer segment membranes of rod photoreceptors are renewed throughout life. When animals were injected with radioactive amino acids to label newly synthesized protein, the first site of incorporation was within the photoreceptor inner segment as had been observed by Droz earlier. Much of this newly synthesized protein was then transported to the outer segment base where it was used to form a band of radioactive outer segment membrane discs. As this process of membrane addition continued, the radioactive band was displaced along the length of the outer segment to the tip where it was shed as a packet of membrane discs.' 28 These membrane fragments were then phagocytized and degraded by the pigment epithelium.' 20 The experiments of Hall et al. further demonstrated that much of the new membrane protein was the rod visual pigment rhodopsin. This pattern of rod outer segment renewal has been observed in every vertebrate examined. Throughout these autoradiographic studies, cone outer segments were observed to become diffusely labeled, but a discrete band of labeled discs was never formed. This led Young to suggest that cone outer segments were renewed by the replacement of individual molecules throughout the outer segment rather than by the rod system of membrane assembly at the base and loss of membrane packets from the tip. However, the morphological studies of cone photoreceptors in the squirrel retina by Anderson, Fisher, and Steinberg" and in the human retina by Steinberg, Wood, and Hogan21