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At least 1,063 records · Page 59Linked to original sources
PubMed1990

Transcription of testicular angiotensin-converting enzyme (ACE) is initiated within the 12th intron of the somatic ACE gene.

Angiotensin-converting enzyme (ACE) is a zinc-containing dipeptidyl carboxypeptidase that catalyzes the conversion of angiotensin I to the potent vasoconstrictor angiotensin II. By analyzing cDNA and genomic DNA, we have constructed a consensus sequence encoding the testis isozyme of mouse ACE. Testis ACE cDNA contains 2,435 base pairs and encodes a protein of 732 amino acids. The N-terminal 66 amino acids are unique to the testis isozyme, while the remaining 666 are identical to the carboxyl half of mouse somatic ACE. The overall conservation of amino acid sequence between the testis isozymes of the mouse, rabbit, and human is 78 to 84%. The conservation of amino acids for the N-terminal domain uniquely expressed within the testis is 63 to 67% between these species. Primer extension and RNase protection experiments show that RNA transcription of the testis ACE isozyme begins 16 or 17 bases upstream from the translation start site. A sequence element resembling a TATA box is found 25 bases 5' of the transcription start site. To create its unique isozyme of ACE, the testis begins mRNA transcription in the middle of the exonic-intronic structure of somatic ACE, within a sequence treated as an intron by somatic tissues. Testis ACE is not the result of alternative RNA splicing but seems due to the start of transcription at a unique site within the ACE gene.

Amino Acid Sequence↗
PubMed1997

Testis-specific expression of the mouse histone gene H1t is regulated by several promoter elements.

The testis-specific histone gene H1t is expressed only in mammalian testis at the stage of pachytene spermatocytes. The tissue-specific regulation of the mouse H1t gene was examined in mouse testicular primary culture cells with gene constructs consisting of H1t promoter elements fused to the chloramphenicol acetyltransferase or the firefly luciferase reporter gene. Our experiments demonstrate that expression of the mouse H1t gene is enhanced by a conserved H1 histone gene-specific TG box 452 base pairs upstream of the transcription start site. The transcription of the H1t gene appears to be reduced by sequences between -1999 and -1506. No regulatory effect could be shown for the H1 box in the expression of the mouse H1t gene. Binding of nuclear protein extracted from mouse testis to these consensus elements was shown by electrophoretic mobility-shift assays with mouse testicular nuclear proteins and labeled oligonucleotides containing the upstream TG box sequences or the two testis-specific elements of the H1t gene.

Animals↗
PubMed1997

Transplantation of testis germinal cells into mouse seminiferous tubules.

In the adult male, germ cell differentiation takes place in the seminiferous tubules of the testis by a complex, highly organized and very efficient process. A population of diploid stem-cell spermatogonia that lie on the basement membrane of the tubule continuously undergoes self-renewal and produces progeny cells, which initiate the process of cellular differentiation to generate mature spermatozoa. Each testis contains many seminiferous tubules, which are connected at both ends to a collecting system called the rete testis. The mature spermatozoa pass from the tubules into the rete and are then carried through efferent ducts to the epididymis for final maturation before they are ready to fertilize an egg. In previous studies, we have demonstrated that donor testis cells collected from a fertile mouse are able to generate spermatogenesis when transplanted to the seminiferous tubules of an infertile male. The spermatozoa produced by the recipient from the donor-derived spermatogonial stem cells are able to fertilize eggs and produce progeny carrying the donor male haplotype. Furthermore, donor testis stem cells from a rat will generate normal rat spermatozoa following transplantation to a mouse testis. The spermatogonial transplantation technique is clearly valuable and applicable to many species, but it is difficult. Therefore, several procedures to introduce donor cells into the seminiferous tubules of a recipient have been developed using the mouse as a model, and they are described here in detail. The results indicate that microinjection of cell suspensions into the seminiferous tubules, efferent ducts or rete testis are equally effective in generating donor cell-derived spermatogenesis in recipients. Each approach is likely to be useful for different experimental purposes in a variety of species.

Animals↗
PubMed2004

Identification and complete sequencing of novel human transcripts through the use of mouse orthologs and testis cDNA sequences.

The correct identification of all human genes, and their derived transcripts, has not yet been achieved, and it remains one of the major aims of the worldwide genomics community. Computational programs suggest the existence of 30,000 to 40,000 human genes. However, definitive gene identification can only be achieved by experimental approaches. We used two distinct methodologies, one based on the alignment of mouse orthologous sequences to the human genome, and another based on the construction of a high-quality human testis cDNA library, in an attempt to identify new human transcripts within the human genome sequence. We generated 47 complete human transcript sequences, comprising 27 unannotated and 20 annotated sequences. Eight of these transcripts are variants of previously known genes. These transcripts were characterized according to size, number of exons, and chromosomal localization, and a search for protein domains was undertaken based on their putative open reading frames. In silico expression analysis suggests that some of these transcripts are expressed at low levels and in a restricted set of tissues.

Amino Acid Sequence↗
PubMed1996

Molecular cloning of mouse somatic and testis-specific H2B histone genes containing a methylated CpG island.

We have isolated a mouse testis-specific H2B histone gene based on the unusual methylation of the CpG island of rat testis-specific H2B gene in somatic tissues. After digestion of genomic DNA with the methylation-sensitive restriction enzyme Hha I, we found that, among 10-20 copies of mouse H2B histone genes, at least three copies are methylated in somatic tissues, but not in testis. Cloning and sequence analysis of two methylated H2B genes revealed that one gene, MTH2B, is strikingly similar to the testis-specific histone H2B (TH2B) gene of rat and the other, psH2B, is a pseudogene of the somatic-type H2B gene. Northern blot analysis revealed that the expression of the MTH2B gene is testis-specific. During spermatogenesis, the MTH2B gene is expressed predominantly in pachytene spermatocytes, as observed in the expression of rat TH2B gene. Interestingly, the MTH2B gene is largely unmethylated in embryonic stem cells, but methylated in F9 embryonal carcinoma cells. The psH2B pseudogene is methylated in somatic tissues and F9 cells, but only partially methylated in embryonic stem cells. Methylation of the psH2B pseudogene seems to be attributed to its location within the context of repetitive sequences including the B1 element. The unmethylation of both H2B histone genes in the testis explains how CpG islands of those histone genes can be maintained during evolution despite heavy methylation in somatic tissues.

Amino Acid Sequence↗
PubMed2004

Immunohistochemical detection of glucose transporters class I subfamily in the mouse, rat and human testis.

A family of glucose transporters (GLUT) mediates the cellular uptake of glucose at the plasma membrane by facilitated diffusion. We investigated the presence of isoforms GLUT1-4 of class I subfamilies in different types of cells in the mouse, rat and human testis by indirect immunofluorescence technique. Immunocytochemical analyses demonstrated that GLUT1 was expressed in the rat testis, GLUT2 in the mouse and rat testis, GLUT3 in the mouse, rat and human testis and GLUT4 was not presented in the testis at all. A very intensive positive immunoreaction for GLUT3 was found in Sertoli cells, peritubular myoid cells, macrophage-like interstitial cells, testicular endothelial cells and early spermatocytes. GLUT3 positive cells were not found in the luminal part of Sertoli cells, spermatids or Leydig cells. The present results suggest that glucose uptake in different testicular cells is mediated by GLUT1, GLUT2 and GLUT3 and the GLUT3 was the prominent glucose transporter type in the testicular cells.

Animals↗
PubMed1993

Age-related morphological changes in the testis of the BDF1 mouse.

Age-related morphological changes in the testis of the BDF1 mouse were studied by light and transmission electron microscopy. No apparent changes were detected until 12 months of age. After 18 months of age, vacuoles firstly appeared in the seminiferous epithelium. These vacuoles were gradually increased in number and showed a tendency to cluster with each other in accordance with age. While, germ cells were decreased in number. The sloughing of germ cells caused a thin seminiferous epithelium. In the tubule with a thin epithelium, spermatogenesis was severely interrupted. After 30 months of age, extremely thin seminiferous epithelia were observed. In these epithelia, most of spermatids and spermatocytes disappeared, and most of Sertoli cells lost their polarity to be flattened. On the other hand, in the interstitial region, PAS-positive cells (mononuclear phagocytes) tended to increase in number after 24 months of age. PAS-positive extracellular matrix newly appeared at 27 months of age. In the cytoplasm of Leydig cells, a whorl of sER was frequently found. Degeneration of testes proceeded with age. The regressive tubules occupied only 2.2% at 18 months of age, but extended to 63.0% at 33 months.

Aging↗