Mori C, Welch J E, Sakai Y, Eddy E M
Gamete Biology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709.
Biol Reprod. 1992 May;46(5):859-68. doi: 10.1095/biolreprod46.5.859.
Northern blot analysis with a cDNA clone for mouse spermatogenic cell-specific glyceraldehyde 3-phosphate dehydrogenase (Gapd-s) previously identified transcripts in isolated round spermatids, but not in isolated pachytene spermatocytes, strongly suggesting that Gapd-s transcription first occurs in haploid germ cells. In the present study, in situ hybridization was carried out with a [35S]-labeled anti-sense RNA probe of Gapd-s to define more precisely the temporal expression and spatial distribution of Gapd-s mRNA in adult mouse testes. Gapd-s transcripts were not detected in spermatogonia, primary spermatocytes, secondary spermatocytes, or spermatozoa. However, they were abundant in round spermatids and condensing spermatids. Transcripts were not detected in somatic cells of the testis, in oocytes in pre-antral or antral follicles, or in skeletal muscle. Grain counts were used to define when the Gapd-s gene was expressed during round spermatid development in adult mice. The number of silver grains first exceeded background levels in step 4-6 spermatids (early cap phase of spermiogenesis) and were high in step 7-15 spermatids (acrosome and elongation phases of spermiogenesis). However, they returned to background levels in step 16 spermatids, the final step of spermiogenesis in the mouse. In 20-day-old juvenile mice, Gapd-s transcripts were first detected in round spermatids during the early cap phase of development. These observations confirmed that Gapd-s mRNA is expressed during the post-meiotic phase of male germ cell development, demonstrated that Gapd-s transcripts are present in step 4-15 spermatids, and established that transcription begins in round spermatids during the early cap phase of spermiogenesis in both juvenile and adult mice.
用小鼠生精细胞特异性甘油醛-3-磷酸脱氢酶（Gapd-s）的cDNA克隆进行的Northern印迹分析，先前已在分离的圆形精子细胞中鉴定出转录本，但在分离的粗线期精母细胞中未鉴定出，这强烈表明Gapd-s转录首先发生在单倍体生殖细胞中。在本研究中，用[35S]标记的Gapd-s反义RNA探针进行原位杂交，以更精确地确定Gapd-s mRNA在成年小鼠睾丸中的时间表达和空间分布。在精原细胞、初级精母细胞、次级精母细胞或精子中未检测到Gapd-s转录本。然而，它们在圆形精子细胞和浓缩精子细胞中大量存在。在睾丸的体细胞、窦前或窦状卵泡中的卵母细胞或骨骼肌中未检测到转录本。用颗粒计数来确定成年小鼠圆形精子细胞发育过程中Gapd-s基因何时表达。银颗粒数量在第4-6步精子细胞（精子发生的早期帽期）首次超过背景水平，并在第7-15步精子细胞（精子发生的顶体和伸长阶段）中较高。然而，在第16步精子细胞（小鼠精子发生的最后一步）中它们又回到了背景水平。在20日龄的幼年小鼠中，在发育的早期帽期首次在圆形精子细胞中检测到Gapd-s转录本。这些观察结果证实了Gapd-s mRNA在雄性生殖细胞发育的减数分裂后阶段表达，表明Gapd-s转录本存在于第4-15步精子细胞中，并确定在幼年和成年小鼠精子发生的早期帽期，转录开始于圆形精子细胞。
