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Y Nishimune

Publications and source records attributed to Y Nishimune.

At least 55 records · Page 3Linked to original sources
PubMed1998

The mouse RecA-like gene Dmc1 is required for homologous chromosome synapsis during meiosis.

The mouse Dmc1 gene is an E. coli RecA homolog that is specifically expressed in meiosis. The DMC1 protein was detected in leptotene-to-zygotene spermatocytes, when homolog pairing likely initiates. Targeted gene disruption in the male mouse showed an arrest of meiosis of germ cells at the early zygotene stage, followed by apoptosis. In female mice lacking the Dmc1 gene, normal differentiation of oogenesis was aborted in embryos, and germ cells disappeared in the adult ovary. Meiotic chromosome analysis of Dmc1-deficient mouse spermatocytes revealed random spread of univalent axial elements without correct pairing between homologs. In rare cases, however, we observed complex pairing among nonhomologs. Thus, the mouse Dmc1 gene is required for homologous synapsis of chromosomes in meiosis.

Adenosine Triphosphatases↗
PubMed1998

Characterization and expression of a stage specific antigen by monoclonal antibody TRA 54 in testicular germ cells.

To study the mechanism of spermatogenesis, we have isolated many monoclonal antibodies (mAb) which recognize specific steps of mouse germ cell differentiation and then have evaluated the specific expression and characterization of antigenic molecules using immunohistochemistry and Western blotting. Monoclonal antibody TRA 54 recognized specific organelles in germ cell cytoplasm from spermatocytes to spermatids; that is, a large granule was stained in mid-late pachytene, diplotene and secondary spermatocytes and in round spermatids at stage I while the acrosome of spermatids at steps 2-3 to step 12 were also positive. Thereafter, the antigens disappeared from spermatids at more advanced stages of differentiation. Western blots using TRA 54 revealed broad bands with approximate molecular weights of >200, 190 and 85 kDa in the testis. The expression of these antigens during testicular germ cell development should be of interest in relation to the biogenesis of organelles such as the chromatoid body and acrosome and will be a useful stage-specific molecular marker for the study of spermatogenesis.

Animals↗
PubMed1998

Expression of selenoprotein-P messenger ribonucleic acid in the rat testis.

It has been suggested that a plasma protein, selenoprotein P, functions as an antioxidant and that its mRNA is expressed ubiquitously, including in the testis. To determine its physiological function, we have investigated the expression of selenoprotein-P mRNA in the rat testis. Northern blot analysis showed that selenoprotein P was exclusively expressed in the Leydig cell fraction. In situ hybridization experiments further supported this observation. Testes of rats administered ethylene dimethane sulfonate (EDS) were also examined by Northern blot analysis. Selective degeneration of Leydig cells by EDS treatment resulted in disappearance of selenoprotein-P mRNA from the testis. Furthermore, upon recovery, in association with regenerative differentiation of Leydig cells, reappearance of the selenoprotein-P mRNA was observed. These results indicated that selenoprotein-P mRNA was predominantly expressed in the interstitial Leydig cells.

Animals↗
PubMed1998

Prevalence of herpes B virus antibody in nonhuman primates reared at the National University of Japan.

A serological investigation by means of an enzyme immuno assay test for herpes B virus (cercopithecine herpesvirus 1) was performed on 961 sera of healthy nonhuman primates reared in laboratory animal facilities which belong to the Association of Laboratory Animal Facilities of the National University of Japan. An antibody prevalence of 40% (384/ 961) was demonstrated. The antibody titer was shown to be higher among macaques (60% of cynomolgus monkeys, 53% of rhesus monkeys, and 34% of Japanese monkeys) than among non-macaque species (21%). These data indicate that nonhuman primates reared in animal facilities may present an occupational health problem and a potential zoonotic biohazard as demonstrated in limited cases in the United States.

Animals↗
PubMed1997

Cloning and characterization of the human Calmegin gene encoding putative testis-specific chaperone.

The putative chaperone Calmegin is required for sperm fertility in mouse and the relevance of the gene to certain cases of human male infertility has been suggested. In the present paper, we have isolated and characterized the human homolog cDNA of the mouse germ cell-specific Calmegin. The entire coding region of the human cDNA showed 80% identity with the previously reported mouse Calmegin. The predicted amino acid sequence showed strong conservation of the two sets of internal repetitive sequences (Ca2+ binding motif), and the hydrophilic COOH terminus, which corresponds to the putative endoplasmic reticulum (ER) retention motif. Our finding will support diagnosis of male infertility. Northern blotting analysis of various human tissues showed that the transcript was 3 kb in length and was expressed exclusively in the testis. Using the fluorescence in situ hybridization (FISH) technique, human Calmegin gene was mapped to chromosome 4q28.3-q31.1.

Amino Acid Sequence↗
PubMed1997

Mapping of eight testis-specific genes to mouse chromosomes.

We previously identified eight testis-specific genes using antibodies raised against testicular germ cells. They are expressed during spermatogenesis and are presumed to be involved in testicular germ cell differentiation and sperm formation. We have mapped the genomic loci for these testis-specific genes using restriction fragment length variants in interspecific backcross mice. The calmegin gene (Clgn) was mapped to Chr 8. The synaptonemal complex protein gene 1 (Sycp1) probe hybridized with two sequences on different chromosomes; Sycp1-rs2 was mapped to Chr 3, whereas Sycp1-rs3 was mapped to Chr 7. The relaxin-like factor gene (Rlnl) was mapped to Chr 8, and collapsin response mediator protein 1 (Crmp1) was mapped to Chr 5. Three novel genes encoding testis-specific proteins A2 (Tsga2), A8 (Tsga8), and A12 (Tsga12) were mapped to chromosomes 3, X, and 10, respectively.

Animals↗
PubMed1997

The putative chaperone calmegin is required for sperm fertility.

The proper folding of newly synthesized membrane proteins in the endoplasmic reticulum (ER) is required for the formation of functional mature proteins. Calnexin is a ubiquitous ER chaperone that plays a major role in quality control by retaining incompletely folded or misfolded proteins. In contrast to other known chaperones such as heat-shock proteins, BiP and calreticulin, calnexin is an integral membrane protein. Calmegin is a testis-specific ER protein that is homologous to calnexin. Here we show that calmegin binds to nascent polypeptides during spermatogenesis, and have analysed its physiological function by targeted disruption of its gene. Homozygous-null male mice are nearly sterile even though spermatogenesis is morphologically normal and mating is normal. In vitro, sperm from homozygous-null males do not adhere to the egg extracellular matrix (zona pellucida), and this defect may explain the observed infertility. These results suggest that calmegin functions as a chaperone for one or more sperm surface proteins that mediate the interactions between sperm and egg. The defective zona pellucida-adhesion phenotype of sperm from calmegin-deficient mice is reminiscent of certain cases of unexplained infertility in human males.

Animals↗
PubMed1997

'Green mice' as a source of ubiquitous green cells.

The green fluorescent protein (GFP) is responsible for the green bioluminescence of the jellyfish Aequorea victoria. Many classes of GFP mutants exist that display modified fluorescence spectra and an increased extinction coefficient. We produced transgenic mouse lines with an 'enhanced' GFP (EGFP) cDNA under the control of a chicken beta-actin promoter and cytomegalovirus enhancer. All of the tissues from these transgenic lines, with the exception of erythrocytes and hair, were green under excitation light. The fluorescent nature of the cells from these transgenic mouse lines would facilitate their use in many kinds of cell transplantation experiments.

Actins↗
PubMed1997

The regulation of membrane cofactor protein (CD46) expression by the 3' untranslated region in transgenic mice.

Regulation of the membrane cofactor protein (MCP: CD46) was examined. While the expression of MCP in mice carrying MCP(BC2) cDNA with 125 bp of 3' untranslated region (3'UT) was minimal, that in mice carrying MCP cDNA without total 3' UT was evident in many organs. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis clearly showed the presence of mRNA even in transgenic mice with 3' UT, suggesting that the expression was regulated at the post-transcriptional stage. The in vitro expression data of MCP molecules on the stable Chinese hamster ovary (CHO) cell clone corresponded to that in transgenic mice. The first 125 bp downregulated the expression of MCP molecules in combination with not only beta-actin, but also SR alpha, promoter. Also, this region inhibited expression of decay accelerating factor (DAF: CD55) molecules when it was inserted into cDNA of DAF. Furthermore, the first 32 bp of the 3' UT revealed the same downregulation effect as 125 bp on MCP molecules. These findings indicated that the first 125 bp (and the first 32 bp in particular) of 3' UT regulate the expression of MCP molecules in transgenic mice.

Animals↗
PubMed1997

Aberrant methylation of an imprinted gene U2af1-rs1(SP2) caused by its own transgene.

Genomic imprinting refers to the parental allele-specific expression of genes. The precise mechanism underlying this phenomenon, which may involve DNA methylation, is not yet known. U2af1-rs1(SP2) is an imprinted gene expressed from the paternal allele and is methylated on the maternal allele. Here we report an artificial system in which expression and methylation of the endogenous imprinted gene U2af1-rs1 can be affected by interaction with its own transgene in the testis. We suggest that there is a mechanism in male gametogenesis by which the U2af1-rs1 gene is kept unmethylated to be expressed in the offspring in addition to a mechanism in female gametogenesis by which the U2af1-rs1 gene is methylated and is not expressed in the offspring.

Alleles↗
PubMed1997

A germ cell-specific nuclear antigen recognized by a monoclonal antibody raised against mouse testicular germ cells.

A monoclonal antibody (mAb TRA 104) raised against mouse testicular germ cells was able to recognize the nuclei of testicular germ cells at all the stages of differentiation from embryonic gonocytes to spermatids and did not react with any somatic cells. The antigen recognized by mAb TRA 104 was exclusively present in testicular extracts. The molecular weights and isoelectric point (pI) of the antigens determined by Western blotting analysis were 60-110 kDa and 7.2, respectively. This antigen(s) is referred to as a germ cell-specific nuclear antigen(s) (GENA) since GENA was first detected specifically in the genital ridge at around 12 days of gestation by Western blotting analysis. In the testis, the expression increased gradually until adulthood whereas it was lost in the ovary by postpartum day 5. Thus, GENA is a molecule(s) exclusively present in the nuclei of germ cells and may be a useful marker with which to study the mechanism of germ cell development and differentiation at the molecular level.

Animals↗
PubMed1997

Coexpression of multiple Sertoli cell and Leydig cell marker genes in the spontaneous testicular tumor of F344 rat: evidence for phenotypical bifurcation of the interstitial cell tumor.

The development of testicular tumor has been frequently observed in some laboratory rat strains. In the present study, we have further characterized the testicular tumor that spontaneously develops in the F344 rat (F344/Jcl). Tumor cells first appeared in the interstitium and developed into multifocal nodular lesions. In the later stage, the whole testes were occupied by tumor cells that consisted of three different types of cells in morphological appearance: large clear type, small eosinophilic type and intermediate type. To determine the character of these cells, we examined the expression of marker genes for Sertoli cells (e.g., transferrin) and Leydig cells (e.g., 3 beta-hydroxysteroid dehydrogenase 1 (3 beta-HSD 1)). Transferrin and 3 beta-HSD 1 mRNAs were found in all 8 tumor samples analyzed by northern blotting. By in situ hybridization, we observed a substantial amount of 3 beta-HSD 1 mRNA and little or no transferrin mRNA in the large clear cells. In contrast, the small eosinophilic cells showed little or no 3 beta-HSD 1 mRNA and a large amount of transferrin mRNA, suggesting that the tumor was a mixture of at least two types of cells. Other Sertoli cell marker genes, such as cyclic protein 2 and sulfated glycoprotein 2, were expressed in all 8 tumors analyzed, and testin and steel factor (SLF), the c-kit receptor ligand, were also expressed in some of the tumors (testin, 75%; SLF, 25%), while other Leydig cell markers, LH receptor and c-kit, were expressed in 87% and 80% of the tumors, respectively. These results indicate that the spontaneous testicular tumor of F344 rat is of interstitium origin, showing phenotypical bifurcation possibly via transdifferentiation.

3-Hydroxysteroid Dehydrogenases↗
PubMed1997

Cessation of spermatogenesis in juvenile spermatogonial depletion (jsd/jsd) mice.

BACKGROUND: Mice homozygous for the jsd (juvenile spermatogonial depletion) allele are sterile because they become azoospermic. The onset of such azoospermia was investigated by histologic analysis of sections of testes from jsd/jsd mice. METHOD: The testes removed from C57BL/6-jsd/jsd mice aged 3 to 10 weeks were examined microscopically. RESULTS: At 3 weeks of age, spermatocytes were seen in most of the seminiferous tubules of jsd/jsd mice. However, the number of tubules that contained spermatids was significantly smaller than that counted in the wild-type mice. Since degenerative figures were not abundant in the jsd/jsd testes, the decreased number of spermatids found in the tubules suggested a longer duration of development from spermatocyte to spermatid in jsd/jsd mice. The abnormality extended to the development of type B spermatogonia, and a decrease in their number became apparent after 6 weeks of age in most of the jsd/jsd tubules. However, as early as 3 weeks of age, a few seminiferous tubules in jsd/jsd mice already contained only Sertoli cells and type A spermatogonia. CONCLUSION: It is assumed that the decrease in type B spermatogonia occurred at various ages and locations. The defect of spermatogenesis in jsd/jsd mice was attributable to aberrations in multiple steps of spermatogenesis.

Aging↗
PubMed1996

A receptor tyrosine kinase, Sky, and its ligand Gas 6 are expressed in gonads and support primordial germ cell growth or survival in culture.

Although a number of growth factors and their receptors are involved in the proliferation and differentiation of primordial germ cells (PGCs), the only factor that has been shown to be active in vivo is Steel factor, a ligand for c-Kit. To identify new growth factor receptors that may be required for PGCs function in vivo, we used an reverse transcription-polymerase chain reaction-based strategy to screen for protein kinase genes expressed in PGC-derived embryonic germ cells. We report here that one such gene encoding the receptor tyrosine kinase, Sky, is expressed in both PGCs and their supporting cells in male genital ridges after 11.5 dpc. Interestingly, Sky expression was not detected in female genital ridges, although transcripts were detected in supporting cells in the developing ovary at later stages. Gas 6, a ligand for Sky, was also expressed in interstitial cells which surround Sky positive cells in genital ridges, and, in addition, it supported PGC growth or survival in culture. After birth, Sky expression in testis was restricted to Sertoli cells, and Gas 6 was detected around peritubular cells and Leydig cells. These results suggest that Gas 6-Sky signaling plays a role in PGC growth, sexual differentiation, and Sertoli cell functions in vivo. Sky expression in Sertoli cells diminished by 3 weeks of age, when haploid germ cells first appear. On the other hand, the expression in Sertoli cells was markedly upregulated in the testis of germ cell-deficient W/Wv and jsd/jsd mice. The results suggest that signals from differentiated germ cells suppress Sky gene expression in Sertoli cells. High-resolution chromosomal mapping of Sky is also reported.

Animals↗