红翅皱膝蝗减数分裂染色体的螺旋与轴结构

用低渗处理和苯酚品红染色,在经过卡诺液(甲醇3∶冰醋酸1)固定和未经固定的红翅皱膝蝗减数分裂染色体上都看到了螺旋结构。观察和测量结果表明,每条染色单体都是由430nm左右的染色线螺旋形成的。由染色线到染色体的压缩率为4∶1。低渗处理后固定的材料经过银染,则显示了染色体轴结构。同样,未经低渗处理直接固定的材料银染时也出现了轴结构。银染的轴结构位于每个染色单体的中央,并贯穿整个染色单体。在光镜下,这个轴并不是直径均一的棒状结构,而似乎是由许多大小相近的颗粒相连而成。本文对染色体结构的有关模型、骨架和轴结构的真实性以及轴和螺旋的关系等问题进行了讨论。

SPIRAL STRUCTURE AND CHROMOSOME CORE IN MEIOTIC CHROMOSOMES OF GRASSHOPPER ANGARACRIS RHODOPA

By using hypotonic treatment and Carbol-fuchsin staining, spiral structures of chromosomes were observed in meiotic chromosomes of Angaracris rhodopa either fixed in a fixative of methanol-acetic acid (3:1) or unfixed. Measurements and analyses of the coiling structure of chromosomes indicate that the chromatid in meiosis of this grasshopper is formed by the helical coiling of the chromonema about 430 nm in diameter and the packing ratio of a chromonema coiled to from a chromatid is about 4:1. When materials trcated with a hypotonic solution and fixed in a mixture of methanol-acetic acid (3:1) were silver stained, chromatid cores were shown within the chromosomes, likewise, chromatid cores were also displayed when chromosomes were silver stained directly without hypotonic treatment. Silver stained core structure is located in the centre of each chromatid and runs longitudinally throghout the length of each chromatid. Under the light microscope, it is evident that the silver stained core is not a uniform rod-like structure but consists of a number of particles in similar size.The models of the higher-order structure of chromosomes, the reality of the scaffold and core structures seen in chromosomes and the possible relationship between chromosome core and coiling structures were discussed.