哺乳动物P1精蛋白基因表达的研究

目的:研究哺乳动物P1精蛋白基因在大鼠和小鼠中的表达。方法:用RT-PCR法制备大鼠P1精蛋白(rP)cDNA,用小鼠P1精蛋白(mP1)DNA重组质粒(pUC8)制备mP1cDNA,rPcDNA和mP1cDNA经迪高辛标记后作为探针,用Northern杂交等技术分析基因表达情况。结果:rPcDNA与大鼠睾丸RNA有杂交反应,而与肝、脑RNA无交叉反应;rPcDNA和小鼠睾丸RNA有交叉反应;mP1cDNA探针与性成熟不同阶段小鼠睾丸RNA杂交结果表明:小鼠性成熟过程中,在睾丸出现圆形精子细胞后mP1基因开始转录,而翻译成蛋白质是在性成熟小鼠睾丸内出现长形精子细胞后。结论:哺乳动物P1精蛋白的表达有器官特异性,是睾丸特异表达的基因,P1精蛋白基因在进化上保守,因而在大、小鼠睾丸中均能检测到杂交讯号;精蛋白基因的表达表现为翻译延迟,该基因在圆形精子细胞阶段开始转录,而在长形精子细胞阶段翻译成蛋白质。

Expression of Mammalian P1 Protamine Gene

Objective:To study the expression of the mammalian P1 protamine gene in rat and mouse. Methods: Rat protamine (rP) cDNA was obtained by using RT-PCR technique. Mouse P1 protamie (mP1) cDNA was prepared from recombinate plasmid pUC8. Dig-labelled rP cDNA and mPl cDNA were used for Northern bolt analysis to study the expression of P1 protamine. Results: P1 protamine mRNA was detect- ed only in rat testis,no hybridization signals were detected in rat brain and liver. In addition, the presence of PI protamine mRNA was detected in both rat testis and in mouse testis. In the process of sexual maturation of mouse, 7-8 d after birth, no mP1 mRNA could be detected; at 24-26 d, mP1 mRNA was detectable migrating as a homogeneous band at 580 nudeotides, whereas in sexually mature animals, a heterogeneous mixture of RNAs ranging from 450-580 bases in length was observed. Histological studies revealed that in the testis of 7 - 8-day-old mouse, spermatogenesis has developed to the spermatocyte stage, whereas round spermatids (Rs) were present in the testis of the 24- 26-day-old mouse and elongating spermatids (Es) were present in the testis of sexually mature animals. Conclusion: P1 protamine gene is tissue-specifically expressed and the P1 protamine is showed to be conservative in evolution. During the process of sexual maturation, along with morphological changes, mP1 gene was transcribed in Rs and translated in Es.