Grandjean V, Hauck Y, Beloin C, Le Hégarat F, Hirschbein L
Institut de Génétique et Microbiologie C.N.R.S-URA 2225, Centre d'Orsay, France.
Biol Chem. 1998 Apr-May;379(4-5):553-7.
Epigenetic mechanisms are not exclusively reserved to eukaryotic organisms. They are also observed in prokaryotes. As described first by Hotchkiss and Gabor, protoplast fusion between strains of Bacillus subtilis produces heterodiploid cells. Heterodiploidy is associated with the inactivation of one of the chromosomes. To study the physical structure of the fusion product and the molecular mechanisms of inactivation, we constructed heterodiploid clones containing two chromosomes labeled by a NotI restriction fragment length polymorphism. In the progeny, we identified haploid recombinant clones that contain a chromosome carrying large regions of inactivated DNA. Studies of both recombinants of the latter kind and heterodiploid cells indicated that chromosomal inactivation was not determined by alteration of the inactivated nucleotide sequence, but was probably due to a modification in the structure of the bacterial chromatin.
表观遗传机制并非真核生物所特有。在原核生物中也能观察到。正如霍奇基斯和加博尔首次描述的那样，枯草芽孢杆菌菌株间的原生质体融合产生异二倍体细胞。异二倍体与其中一条染色体的失活有关。为了研究融合产物的物理结构和失活的分子机制，我们构建了含有两条由NotI限制性片段长度多态性标记的染色体的异二倍体克隆。在后代中，我们鉴定出了单倍体重组克隆，其包含一条携带大片段失活DNA区域的染色体。对后一种重组体和异二倍体细胞的研究表明，染色体失活不是由失活核苷酸序列的改变决定的，而可能是由于细菌染色质结构的改变。
