Burnside B, Smith B, Nagata M, Porrello K
J Cell Biol. 1982 Jan;92(1):199-206. doi: 10.1083/jcb.92.1.199.
Teleost retinal cones contract in the light and elongate in the dark. In the green sunfish, Lepomis cyanellus, the necklike myoid region of the cone contracts from as much as 120 micrometers (midnight dark-adapted) to 6 micrometers in fully light-adapted state. When dark-adapted fish are exposed to light (1.4 lux), cone myoids contract with a linear rate of 1.5 +/- 0.1 micrometers/min. We report here that detergent-lysed motile models of teleost retinal cones exhibit calcium- and ATP-dependent reactivated contraction, with morphology and rate comparable to that observed in vivo. For reactivation studies isolated dark-adapted retinas were lysed with nonionic detergent Brij-58 (0.1-1.0%). In reactivation medium containing 10(-5) M free calcium and 4 mM ATP, the lysed cones contracted with normal morphology at in vivo rates (1.4 +/- 1 micrometer/min). Little contraction was observed if ATP or detergent was deleted from the medium or if free calcium levels were less than 10(-8) M. Ultrastructural examination of cone models lysed with 1% Brij-58 revealed that, in spite of extensive extraction of the cytoplasmic matrix, cytoskeletal components (thin filaments, intermediate filaments, microtubules) were still present. Thus we have produced extensively extracted motile models of teleost retinal cones which undergo calcium- and ATP-dependent reactivated contraction with normal morphology at physiological rate.
硬骨鱼视网膜视锥细胞在光照下收缩，在黑暗中伸长。在绿太阳鱼（Lepomis cyanellus）中，视锥细胞的颈部类肌样区域从午夜暗适应状态下的多达120微米收缩至完全光适应状态下的6微米。当暗适应的鱼暴露于光照（1.4勒克斯）时，视锥细胞的肌样以1.5±0.1微米/分钟的线性速率收缩。我们在此报告，硬骨鱼视网膜视锥细胞经去污剂裂解后的运动模型表现出钙和ATP依赖性的再激活收缩，其形态和速率与体内观察到的情况相当。为了进行再激活研究，将分离的暗适应视网膜用非离子去污剂Brij - 58（0.1 - 1.0%）裂解。在含有10⁻⁵M游离钙和4mM ATP的再激活培养基中，裂解后的视锥细胞以体内速率（1.4±1微米/分钟）正常形态收缩。如果从培养基中去除ATP或去污剂，或者游离钙水平低于10⁻⁸M，则几乎观察不到收缩。用1% Brij - 58裂解的视锥细胞模型的超微结构检查显示，尽管细胞质基质被大量提取，但细胞骨架成分（细肌丝、中间丝、微管）仍然存在。因此，我们制备了大量提取的硬骨鱼视网膜视锥细胞运动模型，这些模型在生理速率下以正常形态经历钙和ATP依赖性的再激活收缩。
