Department of Biological Sciences, Asahikawa Medical University, Asahikawa, Japan.
Int J Radiat Biol. 2011 Mar;87(3):320-9. doi: 10.3109/09553002.2011.530334. Epub 2010 Nov 19.
To quantitatively and qualitatively investigate the changes in chromosomal aberrations during early cleavage in mouse embryos derived from γ-irradiated spermatozoa.
Mature males were exposed to 2 Gy or 4 Gy of ¹³⁷Cs γ-rays, and their spermatozoa were used to produce embryos via in vitro fertilisation (IVF). The metaphase chromosomes were prepared from one-cell, two-cell, and four-cell embryos. In the chromosome preparations from two-cell and four-cell embryos, the separation of the sister blastomeres was precluded by treatment of the embryos with concanavalin A. The incidence of embryos with structural chromosomal aberrations, aneuploidy, or mosaicism was estimated. The fates of the different types of γ-ray-induced structural chromosomal aberrations were also investigated in those embryos.
The exposure of spermatozoa to 2 Gy or 4 Gy γ-rays caused structural chromosomal aberrations in 25.9% and 35.7% of the resultant one-cell embryos, respectively. At two-cell embryonic stage, the incidence of structural chromosomal aberrations was 17.4% in the 2 Gy group and 27.1% in the 4 Gy group. At the four-cell embryonic stage, although the incidence of control embryos with structural chromosomal aberrations was considerably high, the net incidence of embryos with radiation-induced structural chromosomal aberrations was similar to that at the one-cell stage. The incidence of aneuploidy was high in two-cell and four-cell embryos after both doses of γ-rays. The incidence of mosaicism increased significantly in dose- and embryonic-stage-dependent manners. Anaphase lag, and the degeneration and non-disjunction of the aberrant chromosomes were frequently observed in aneuploid and mosaic embryos.
Mouse sperm DNA is highly vulnerable to γ-rays. The structural chromosomal aberrations of sperm origin are unstable in their behaviour and structure during cleavage, and therefore cause secondary aneuploidy and mosaicism in the early cleavage embryos.
定量和定性研究来源于γ射线照射精子的小鼠胚胎在早期卵裂中染色体畸变的变化。
成熟雄性接受 2Gy 或 4Gy 的 ¹³⁷Cs γ射线照射，并用其精子通过体外受精（IVF）产生胚胎。从单细胞、二细胞和四细胞胚胎中制备中期染色体。在二细胞和四细胞胚胎的染色体制备中，通过用刀豆球蛋白 A 处理胚胎来防止姐妹卵裂球的分离。估计具有结构染色体畸变、非整倍体或镶嵌型的胚胎的发生率。还研究了不同类型的γ射线诱导的结构染色体畸变在这些胚胎中的命运。
精子暴露于 2Gy 或 4Gy γ射线分别导致 25.9%和 35.7%的单细胞胚胎发生结构染色体畸变。在二细胞胚胎阶段，2Gy 组的结构染色体畸变发生率为 17.4%，4Gy 组为 27.1%。在四细胞胚胎阶段，尽管对照胚胎具有结构染色体畸变的发生率相当高，但具有辐射诱导的结构染色体畸变的胚胎的净发生率与单细胞阶段相似。二细胞和四细胞胚胎在两种剂量的 γ射线后均出现高非整倍体率。镶嵌型的发生率以剂量和胚胎阶段依赖的方式显著增加。在非整倍体和镶嵌型胚胎中经常观察到后期滞后、畸变染色体的退化和不分离。
小鼠精子 DNA 对 γ射线高度敏感。来源于精子的结构染色体畸变在其行为和结构在卵裂过程中不稳定，因此在早期卵裂胚胎中引起继发性非整倍体和镶嵌型。
