Pittoggi C, Zaccagnini G, Giordano R, Magnano A R, Baccetti B, Lorenzini R, Spadafora C
Institute of General Biology, University of Siena, Italy.
Mol Reprod Dev. 2000 Jun;56(2 Suppl):248-51. doi: 10.1002/(SICI)1098-2795(200006)56:2+<248::AID-MRD7>3.0.CO;2-V.
Exogenous DNA molecules are spontaneously taken up by sperm cells, internalized in nuclei, and eventually integrated in the sperm genome. The actual occurrence of the integration suggests that the sperm chromosomal DNA is not uniformly and tightly packed with protamines, implying the existence of genomic sites where the chromosomal DNA is accessible to foreign molecules. We have characterized a hypersensitive, nucleosomal subfraction of mouse sperm chromatin that is highly enriched in unmethylated retroposon DNA from a variety of families. Here we propose that both the integration of exogenous DNA molecules, and the endogenous retroposition activity, occur in the same site(s) of sperm chromatin.
外源DNA分子会自发地被精子细胞摄取，内化于细胞核中，并最终整合到精子基因组中。整合的实际发生表明精子染色体DNA并非均匀且紧密地与鱼精蛋白结合，这意味着存在染色体DNA可被外源分子接近的基因组位点。我们已经对小鼠精子染色质的一种超敏感核小体亚组分进行了表征，该亚组分高度富集来自各种家族的未甲基化逆转座子DNA。在此我们提出，外源DNA分子的整合以及内源性逆转座活性均发生在精子染色质的相同位点。
