用DDRT-PCR方法克隆小鼠精子发生早期相关基因的EST

为了避免差异显示技术中的放射性污染 ,并用之于筛选、克隆精子发生早期的相关基因 ,分离纯化了小鼠的原始精原细胞及B型精原细胞 ,提取其总RNA ,逆转录获得cDNA ,以荧光差异显示方法筛选差异表达基因。利用斑点杂交技术对差异片段进行快速鉴定以排除假阳性。选取 16条差异显著的片段做克隆测序 ,通过Gen Bank/Blast比较 ,有 7个片段属于新的EST ,且均表现为在B型精原细胞中表达强度高于原始精原细胞。提交Gen Bank获得注册号。从中选取较有意义的 3条基因片段通过半定量RT PCR方法进一步验证其表达特征。和传统的差异显示方法比较 ,文中所采用的mRNA差异显示技术可快速排除假阳性结果 ,避免同位素标记带来的放射性污染。结果表明所获得的 7个新EST均表现为B型精原细胞中高表达 ,这些表达升高的基因可能与其后精子发生过程中的一系列特殊现象 (如减数分裂、变态成形 )有关 ,为生精细胞的分化做物质上的准备。

Cloning of ESTs of Spermatogenesis-related Genes From Early Stage Spermatogenic Cells of Mice Using a Modified DDRT-PCR Method

To avoid the shortcomings of radioactive pollution and high rate of false positives in DDRT-PCR method, the technique have been modified by replacement of radioactive reagents with fluorescent reagents followed by confirming the results using reverse RNA dot blot. The modified DDRT-PCR method was used in this study to clone spermatogenesis-related genes from early stage spermatogenic cells of mice. Primitive spermatogonia were isolated from 6-day-old mice and type B spermatogonia from 9-day-old mice. The purity of isolated cells was over 90%. Total RNA was extracted from the cells, fluorescent differential display technique was performed to screen the differentially expressed genes. Differences in expression of the screened fragments were identified by reverse RNA dot blot. 16 ESTs were selected for sequencing. The analysis results in GenBank/Blast database revealed that 7 of them were novel ESTs, and they were then registered in GenBank. All of them expressed stronger in B spermatogonia than in primitive spermatogonia. 3 of them were chosen to further identify their expression patterns by semi- quantitative RT-PCR. Compared with traditional differential display technique, the modified method used in this study can avoid radioactive pollution and eliminate false positive results. The present study suggests that the gene activation or up-regulation in B spermatogonia may be related to some specific process in the following steps of spermatogenesis.