RAPID SYNTHESIS AND DESTRUCTION OF PHOTORECEPTOR MEMBRANE BY A DINOPID SPIDER - DAILY CYCLE
RAPID SYNTHESIS AND DESTRUCTION OF PHOTORECEPTOR MEMBRANE BY A DINOPID SPIDER - DAILY CYCLE
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DOI：
10.1098/rspb.1978.0027
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发表时间：
1978-01-01
期刊：
影响因子：
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通讯作者：
BLEST, AD
中科院分区：
文献类型：
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作者：
BLEST, AD
地龙后正中眼的感受节横断面为六角形，6个面各由横纹肌组成。支持细胞的突起在横纹的交界处被简化为链，并且6个横纹的每一个都与不同接受节段的横纹相连；这种排列允许细胞之间光和电耦合的可能性。白天，感受节较短，横纹肌膜仅占其体积的一小部分。夜幕降临时，片段加长，新的膜被加入到快速合成的过程中，几乎填满了片段。黎明时，顺序颠倒，膜以吞饮小泡的形式被移除，这些小泡组装成多囊泡体，并裂解在横纹之间的细胞质和视网膜下肿胀的感受器轴突中。膜的合成和破坏显然在一定程度上是由视网膜光照的即时状态控制的，这些状态叠加在日常节律上。这种代谢过度的系统的进化不太可能主要与适应状态的操纵有关，因此提出了一些替代假设来解释它。
Receptive segments of the posterior median eyes of Dinopis subrufus are hexagonal in transverse profile, and each of the 6 faces is composed of a rhabdomere. Supportive cell processes are reduced to strands at the junction of the rhabdoms, and each of the 6 rhabdomeres is contiguous with the rhabdomere of a different receptive segment; this arrangement allows the possibility of optical and electrical coupling between cells. During the day, receptive segments are short, and rhabdomere membrane occupies only a small proportion of their volumes. At nightfall, the segments lengthen, and novel membrane is added in a rapid burst of synthesis almost to fill them. At dawn, the sequence is reversed, and the membrane is removed as pinocytotic vesicles which are assembled into multivesicular bodies and lysed in the inter-rhabdomeral cytoplasm and in the swollen receptor axons which underlie the retina. Synthesis and destruction of membrane apparently are controlled in part by immediate states of retinal illumination, superimposed upon a daily rhythm. The evolution of this metabolically extravagant system is unlikely to be primarily concerned with manipulation of states of adaptation, and some alternative hypotheses are proposed to account for it.