Bedo D G
Chromosoma. 1975 Jul 21;51(3):291-300. doi: 10.1007/BF00284822.
Polytene and mitotic chromosomes of Simulium ornatipes and S. melatum were subjected to C banding procedures. In both species polytene chromosomes consistently show C banding of centromere regions, telomeres, nucleolar organiser and, unexpectedly, numerous interstitial sites. The interstitial C banding sites correspond to morphologically single polytene bands. Their response is graded and independent of band size. Interstitial C bands in S. ornatipes are scattered throughout the complement, whereas in S. melatum they are clustered. Supernumerary heterochromatic segments in S. ornatipes also exhibit strong C banding and inverted segments can differ from standard in C banding pattern. -- Mitotic chromosomes of both species show a single centric C band with indications of two weak interstitial bands in S. ornatipes, suggesting that many C band regions, detectable in polytene chromosomes, are not resolved by present techniques in mitotic chromosomes. -- Contrary to current opinion that C banding is diagnostic for constitutive heterochromatin, the interstitial C band sites of polytene chromosomes are regarded as euchromatic. Conversely, the heterochromatic pericentric regions of S. ornatipes are not C banded. -- It appears that polytene chromosomes offer a promising system for the elucidation of C banding mechanisms.
对饰颜蚋和黑足蚋的多线染色体和有丝分裂染色体进行了C带处理。在这两个物种中，多线染色体始终显示着丝粒区域、端粒、核仁组织区以及意外出现的众多居间位点的C带。居间C带位点对应于形态学上单一的多线带。它们的反应呈梯度变化且与带的大小无关。饰颜蚋的居间C带散布于整个染色体组，而黑足蚋的居间C带则成簇分布。饰颜蚋的超数异染色质片段也表现出强烈的C带，并且倒位片段在C带模式上可能与标准片段不同。——这两个物种的有丝分裂染色体均显示出单一的着丝粒C带，饰颜蚋有迹象表明存在两条较弱的居间带，这表明在多线染色体中可检测到的许多C带区域，在有丝分裂染色体中目前的技术无法分辨。——与目前认为C带是组成型异染色质的诊断特征的观点相反，多线染色体的居间C带位点被视为常染色质。相反，饰颜蚋的异染色质着丝粒周围区域没有C带。——看来多线染色体为阐明C带机制提供了一个有前景的系统。
