Redi C A, Garagna S, Mazzini G, Winking H
Chromosoma. 1986;94(1):31-5. doi: 10.1007/BF00293527.
The pericentromeric heterochromatin of meiotic trivalents formed by the Robertsonian (Rb) chromosomes and the two homologous acrocentrics in the house mouse was evaluated by static cytophotometry after selective staining. To reveal pericentromeric heterochromatin specifically, C-banding Giemsa and Hoechst 33258 stains were utilized. Five different Rb chromosomes were investigated and none of them possessed less pericentromeric heterochromatin than the sum of the two homologous acrocentrics. Moreover the total A-T (DAPI) and DNA (PI) content was quantitatively evaluated, by flow cytometry, in G0/G1 nuclei belonging to four different Rb mouse populations, karyotypically characterized by the presence of up to nine Rb chromosomes. Again there were no significant difference, of DAPI and PI content, in the Rb populations nor between any of them and the NMRI/HAN strain with forty acrocentric chromosomes. We conclude that the main consequence of Robertsonian processes (i.e. the rapid variation of the karyotype structure) does not imply detectable quantitative variation in the genome portion involved in the Rb process. We also discuss the possibility that the high rate of Rb exchange in the house mouse could be favoured by the simultaneous effects of undetectable losses of chromosomal material, high repetitiveness of the DNA involved, the presence of the same major type of satellite DNA over each chromosome and the all acrocentric constitution of the karyotype.
通过选择性染色后的静态细胞光度法，对小家鼠中由罗伯逊易位（Rb）染色体以及两条同源近端着丝粒染色体形成的减数分裂三价体的着丝粒周围异染色质进行了评估。为了特异性地显示着丝粒周围异染色质，使用了C带吉姆萨染色和Hoechst 33258染色。研究了五条不同的Rb染色体，它们的着丝粒周围异染色质均不少于两条同源近端着丝粒染色体的异染色质总和。此外，通过流式细胞术对属于四个不同Rb小鼠群体的G0/G1期细胞核中的总A-T（DAPI）和DNA（PI）含量进行了定量评估，这些群体的核型特征是存在多达九条Rb染色体。同样，在Rb群体之间以及它们与具有四十条近端着丝粒染色体的NMRI/HAN品系之间，DAPI和PI含量均无显著差异。我们得出结论，罗伯逊易位过程的主要后果（即核型结构的快速变化）并不意味着参与Rb过程的基因组部分存在可检测到的定量变化。我们还讨论了小家鼠中Rb交换率高的可能性，这可能受到染色体物质不可检测的丢失、所涉及DNA的高重复性、每条染色体上存在相同主要类型的卫星DNA以及核型的全近端着丝粒构成的同时影响。
