College of Animal Science and Technology, Chongqing Key Laboratory of Forage & Herbivore, Southwest University, Beibei, Chongqing 400716, People's Republic of China.
Mol Biol Rep. 2011 Mar;38(3):1621-8. doi: 10.1007/s11033-010-0272-2. Epub 2010 Sep 17.
As one of the transport systems on the sperm plasma membrane, CD4 molecule plays a distinct role in the process of sperm/DNA interaction. This makes it possible to explain the mechanism of sperm-mediated gene transfer (SMGT), which at present is still a mystery in this area. In this study, seminal samples of 60 individuals from seven breed bucks were collected to detect the ability of sperm in internalizing exogenous DNA, and genomic DNA from 147 individual blood samples (including 60 bucks referred ahead) were extracted to test the polymorphisms of CD4 genes by using PCR-SSCP technique. Then the correlation between them was evaluated. The results showed that: (1) it was a novel finding that breed-dependence of exogenous DNA binding to goat spermatozoa. There was the most significant difference among the buck breeds of sperm in binding exogenous DNA (F((6, 53)) = 4.811, P = 0.001) and in internalizing them into nuclei (F((6, 53)) = 4.587, P = 0.001). The ability of Lezhi Black goat was the lowest (P < 0.01) among the seven breeds. (2) There was no significant correlation between the ability of sperm in internalizing exogenous DNA and each semen quality parameter (P > 0.05). (3) In particular, three single-nucleotide polymorphisms (SNP) were described and there was one SNP (G/A(700)) of CD4 gene that made G234R substitution in the amino acid sequence of CD4 molecule. Nanjiang Yellow goat and Lezhi Black goat had higher hereditary variation compared with other breeds. (4) CD4 polymorphisms were highly associated with the ability of sperm in internalizing exogenous DNA. The SNP of Caprine CD4 gene exon 6 might be an important molecular marker of the ability to internalize exogenous DNA into sperm.
作为精子质膜上的转运系统之一，CD4 分子在精子/DNA 相互作用过程中发挥着独特的作用。这使得解释精子介导的基因转移（SMGT）的机制成为可能，而目前这一领域仍然是一个谜。本研究采集了 7 个品种公鹿的 60 份精液样本，检测精子内化外源 DNA 的能力，并提取了 147 份个体血液基因组 DNA（包括 60 头公鹿），应用 PCR-SSCP 技术检测 CD4 基因多态性，评估它们之间的相关性。结果表明：（1）本研究首次发现，不同品种的公鹿对外源 DNA 与精子结合的能力存在品种依赖性，公鹿精子对外源 DNA 的结合能力（F((6, 53)) = 4.811，P = 0.001）和内化到核内的能力（F((6, 53)) = 4.587，P = 0.001）差异极显著，其中乐至黑山羊的结合能力最低（P < 0.01）。（2）精子内化外源 DNA 的能力与各精液质量参数均无显著相关性（P > 0.05）。（3）本研究共发现 3 个单核苷酸多态性（SNP），其中 CD4 基因的一个 SNP（G/A(700))，导致 CD4 分子氨基酸序列第 234 位甘氨酸（G）突变为精氨酸（R）。南江黄羊和乐至黑山羊与其他品种相比，具有更高的遗传变异。（4）CD4 多态性与精子内化外源 DNA 的能力密切相关。山羊 CD4 基因外显子 6 的 SNP 可能是精子内化外源 DNA 能力的重要分子标记。
