Michailova P, Ramella L, Sella G, Bovero S
Insitute of Zoology, Bulgarian Academy of Sciences, Tzar Osvoboditel, Sofia, Bulgaria.
Cytobios. 1997;90(362-363):139-51.
C banding in polytene chromosomes of Chironomus riparius from a Santena polluted station of the river Po, Italy was described. A large variation in the appearance of C bands was established. The process involved the transformation of euchromatin into heterochromatin. Activation of all chromosomes at telomeres was found. A structural modification of telomeric heterochromatin may exist. The centromeric heterochromatin was rarely observed. A high percentage of an amplification (88%) in arm F, B3h, was recorded. These changes in the appearance of heterochromatin in the population studied could be considered as a type of polymorphic system, existing in the polluted population. For the first time in C. riparius two types of position effect variegation are reported. In arm E the euchromatin near to the centromere became inactive due to a heterozygous inversion and in arms D and F the opposite phenomenon was observed in which a heterozygous inversion partly suppressed the inactivation of heterochromatin.
描述了来自意大利波河桑泰纳污染站点的里氏摇蚊多线染色体的C带。确定了C带外观的巨大差异。该过程涉及常染色质向异染色质的转化。发现端粒处所有染色体均被激活。端粒异染色质可能存在结构修饰。着丝粒异染色质很少被观察到。记录到F臂、B3h臂有高比例（88%）的扩增。在所研究群体中异染色质外观的这些变化可被视为一种多态系统类型，存在于受污染群体中。首次在里氏摇蚊中报道了两种位置效应斑驳类型。在E臂中，靠近着丝粒的常染色质由于杂合倒位而失活，而在D臂和F臂中观察到相反的现象，即杂合倒位部分抑制了异染色质的失活。
