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T Imamichi

Publications and source records attributed to T Imamichi.

At least 19 recordsLinked to original sources
PubMed1992

Polymorphic microsatellite loci of the rat (Rattus norvegicus).

The EMBL and GenBank DNA databases were searched for microsatellite sequences of the rat containing dinucleotide repeats of (CA)n and (GA)n. Among those obtained, 23 sequences were analyzed by polymerase chain reaction to examine the size variation of the amplified fragment in inbred rat strains. All of the 23 microsatellite sequences varied in size among the strains tested. The 23 microsatellite loci in a pair of substrains separated from the same progenitor strain were then analyzed. Fragments identical in size were observed in all loci of the two substrains, indicating the stability of the microsatellite over a large number of generations. The microsatellite loci, therefore, should be useful markers for linkage analyses in the rat.

Animals↗
PubMed1992

A polymorphism detected in a variable number of tandem repeats (VNTR) of the seminal vesicle secretion (SVS) IV gene in inbred rats.

The second intron of the rat SVS IV gene contains a tandem repeat region of 20-bp sequences. This region was amplified using the polymerase chain reaction to detect variations. Three alleles, characterized by amplified fragments of 750, 490, and 390 bp, respectively, were found in 24 strains examined. This variation segregated in F1 and backcross progeny in an autosomal codominant manner. We tentatively designated this locus Svs-4. Analysis of linkages between the Svs-4 locus and other loci revealed that it was closely linked to the Svp-1 (less than 2.9%) and the a (10.0 +/- 6.7%) loci, which belong to rat linkage group IV. The Svp-1 and Svs-4 loci, however, were differently distributed among the inbred rat strains.

Alleles↗
PubMed1992

Sexing of mouse preimplantation embryos by detection of Y chromosome-specific sequences using polymerase chain reaction.

Detection of genes known to be present on the mammalian Y chromosome was adapted for sexing mouse early embryos using the polymerase chain reaction (PCR) method. Sry and Zfy genes located in the sex-determining region of the Y chromosome were chosen for Y-specific target sequences, and DXNds3 sequence on the X chromosome was chosen for control. The two-step PCR method using two pairs of primers for each of the target sequences was employed for detecting the sequences. When DNAs of male and female mice were amplified with these primers, male-specific fragments were detected even in DNAs that were equivalent in amount to two cells. Mouse embryos at the two-cell stage were separated into two individual blastomeres, and one blastomere was karyotyped at the second cleavage. The remaining blastomere was subjected to PCR amplification immediately or after having been cultured for 48 h up to the morula stage. The Sry and Zfy sequences were detected in about half the embryos; detection of the Sry and Zfy sequences corresponded exactly to the presence of the Y chromosome, except in one sample of male morula in which embryos may have been lost before the PCR amplification. It is concluded that the sex of mouse preimplantation embryos can be accurately determined through detection of the Y-specific sequences using the two-step PCR method, even with the single blastomeres separated at the two-cell stage.

Animals↗
PubMed1992

An aspermia rat mutant (as/as) with spermatogenic failure at meiosis.

A newly identified aspermia rat mutant was investigated on testicular histology and mode of inheritance of the defect. Average testis weight of mutants was about one-third of that of phenotypically normal males. Spermatogenesis was interrupted at meiosis. Pachytene spermatocytes significantly decreased in number. Secondary spermatocytes and few round spermatids were seen, but no elongated spermatids and sperms were observed. A large basophilic inclusion-like body existed in the cytoplasm of late pachytene spermatocytes. Genetic analysis revealed an autosomal recessive transmission of the defect. Aspermia (As) was designated for the locus.

Animals↗
PubMed1992

[Effect of age on the copulatory behavior of the male rat].

Fifteen male SPF Wistar-Imamichi rats, aged 10, 27 and 44 weeks, that had been raised in the authors' laboratory, were used for the observation of copulatory behavior. Each male was given the opportunity to mate with a proestrous female. During a two hour period, standard measures of copulatory behavior, e.g., mounting, intromission and ejaculation, were documented by a video recording. The following results were obtained; the number of ejaculations in 10-week-old rats, over a two hour period, was 6 to 8. Males showed a subsequent post-ejaculatory interval. The males aged 27 weeks performed 3 to 4 times during the first hour, and then refrained from sexual activity. The copulatory behavior in males aged 44 weeks declined, as compared with that of their 10 and 27 weeks old counterparts.

Aging↗
PubMed1992

[A new esterase locus, Es-19, in the rat].

A new esterase polymorphism was identified in epididymal homogenates from inbred rat strains by polyacrylamide gel electrophoresis. The inbred rat strains showed either fast (A) or slow (B) bands. Strain distributions of the phenotypes differed from those of other esterase loci. Genetic analyses revealed that the polymorphism is controlled by codominant alleles (Es-19a and Es-19b) and is not linked to linkage groups, I, II, IV, V, VI, XIII of the rat.

Alleles↗
PubMed1990

Two distinct types of Fc receptor for IgG on guinea pig macrophages activate the NADPH oxidase through different signal-transduction pathways.

Neither 5 microM calmodulin antagonist W-7 nor depletion of the intracellular Ca2+ affected the O2- generation triggered by the Fc receptor for IgG2 (Fc gamma 2 R) on guinea pig macrophages, although that by the Fc receptor for both IgG1 and IgG2 (Fc gamma 1/gamma 2 R) was lowered to 50% of a control level by W-7 and the Ca2+ depletion, respectively. Staurosporine inhibited all these responses, but to different extents. These results reveal that the signal-transduction pathways linked to these receptors differ from each other, and that Fc gamma 1/gamma 2 R triggers the O2- generation through the Ca2(+)-calmodulin system and the Ca2(+)-independent system.

Animals↗
PubMed1990

Restriction fragment length polymorphisms detected in N-ras-related sequences of rats and their linkage analyses.

Novel restriction fragment length polymorphisms (RFLPs) in inbred rats were revealed with the human N-ras gene as probe. Three fragments hybridizing to the probe were detected by Southern blot hybridization under highly stringent conditions, and one of the fragments showed variation in inbred rat strains. Furthermore, on hybridization under low-stringency conditions, an additional fragment hybridizing to the probe was observed, and this fragment also showed interstrain variation. These two variant fragments showed different distributions in 27 inbred rat strains and segregated in backcross progeny as codominant alleles of independent single autosomal loci. Therefore, the loci for these RFLPs were named Nras-1 and Nras-2, respectively. Analyses of linkages between the RFLPs and 11 other loci revealed that the Nras-2 locus was closely linked to the c locus (3.7 +/- 2.6%), which belongs to rat linkage group I.

Animals↗
PubMed1990

Different abilities of two types of Fc gamma receptor on guinea-pig macrophages to trigger the intracellular Ca2+ mobilization and O2- generation.

When exposed to hen ovalbumin (OA)-complexed IgG antibodies, guinea-pig macrophages undergo O2- generation and a rapid rise in the intracellular concentration of free Ca2+ ((Ca2+]i). These responses were found to depend on the IgG isotype of antibodies used; OA-complexed IgG2 antibody (OA gamma 2) induced these responses 3-5 times more intensively than did OA-complexed IgG1 antibody (OA gamma 1). The inhibitory effects of monoclonal antibody to Fc gamma receptor for IgG2 alone (Fc gamma 2R) and that to Fc gamma receptor for both IgG1 and IgG2 (Fc gamma 1/gamma 2R) showed that Fc gamma 2R triggered both an increase in [Ca2+]i and activation of the respiratory burst NADPH oxidase more effectively than did Fc gamma 1/gamma 2R. As the number of Fc gamma 2R molecules per macrophage is about one-half that of Fc gamma 1/gamma 2R molecules, the ability of Fc gamma 2R to trigger these responses may be much higher than that of Fc gamma 1/gamma 2R. This difference between their abilities was further demonstrated by measuring the responses induced by cross-linking of Fc gamma 2R or Fc gamma 1/gamma 2R molecules. In addition, the O2- generation with OA gamma 1 was found to be enhanced with cytochalasin B, and to be lowered by depletion of the intracellular Ca2+ of macrophages with Ionomycin and EGTA, though cytochalasin B and the Ca2+ depletion did not affect the O2- generation with OA gamma 2. These results suggest that the mechanisms of Fc gamma 2- and Fc gamma 1/gamma 2 R-mediated signal transmission leading to activation of the NADPH oxidase also differ from each other.

Animals↗
PubMed1990

Different effects of cinnamic acid on the O2- generation by guinea pig macrophages stimulated with a chemotactic peptide and immune complex.

Cinnamic acid inhibits the O2(-)-generating response of guinea pig peritoneal macrophages elicited with a chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP), but not those with ovalbumin complex of immunoglobulin G2 antibody and phorbol-myristate acetate. During the course of study on the inhibitory mechanism of cinnamic acid, we found that the acid also inhibited the Ca2+ mobilization elicited with fMLP, but not that with the immune complex. In addition, the treatment of macrophages with Ionomycin and ethyleneglycol bis-(beta-aminoethylether)-N,N'-tetraacetic acid for depletion of the intracellular Ca2+ inactivated completely the O2- generation elicited with fMLP, but not its counterpart of the immune complex. Thus, the inhibitory activity of cinnamic acid on the O2- generation elicited with fMLP seems partly due to that on the Ca2+ mobilization. On the other hand, cinnamic acid augmented the intracellular accumulation of adenosine 3',5'-cyclic monophosphate (cyclic AMP) in the presence of 3-isobutyl 1-methylxanthine (IBMX), and elevated more intensively the concentration of cyclic AMP when macrophages were stimulated with fMLP. Since IBMX inhibited the O2- generation elicited with fMLP, the enhancement of activation of an adenylate cyclase by cinnamic acid might cause depression of the O2- generation. This possibility, however, seems to be excluded by the fact that the same effect of cinnamic acid was observed even when macrophages were stimulated with the immune complex.

Animals↗
PubMed1990

Polymorphisms detected in actin-related sequences of rats (Rattus norvegicus).

Southern blot hybridization of EcoRI digests of DNAs from 13 rat strains using human cardiac actin gene as a probe revealed polymorphisms in actin-related sequences of rats. EcoRI fragments of 11 kb, 7 kb, 6 kb, 5 kb, 4.5 kb and 4 kb detected in several strains were absent in the remaining strains. The presence of these fragments was suggested to be due to presence of extra sequences homologous to the actin genes, such as processed pseudogenes, in the particular strains. The 13 strains were assigned to each of 7 specific patterns of the polymorphic EcoRI fragments. It was concluded that the polymorphisms of actin-related sequences should be useful for genetic monitoring of laboratory rats.

Actins↗
PubMed1990

[Ragged--a new rexoid mutant rat with large sebaceous gland].

A new hair defected mutant rat was established. This mutant was covered with ragged hair since about 10 days of age, then transiently lost most of hair in the back at approximately 5 weeks of age and re-covered with ragged hair thereafter. Thickened eyerids occurred since about 3 weeks of age. Histological examination revealed enlarged sebaceous glands with greater number of sebaceous cells in the back skin. The oil stained skin samples showed normal sebaceous transformation and pilosebaceous canal. Genetical analysis showed that the ragged hair character was a single recessive trait and indicated that this single recessive gene was not linked with the coat color genes, non-agouti (a), albino (c) and hooded (h). From the present data and previous reports, we recommended this single recessive gene is a new rexoid mutation thereby we termed this gene "Ragged (rg)".

Animals↗
PubMed1989

Novel restriction fragment length polymorphism of the growth hormone gene in inbred rats.

A novel restriction fragment length polymorphism in inbred rats was detected by Southern blot analysis with rat growth hormone cDNA as a probe. Four alleles, characterized by PstI fragments of 1.2, 1.1, 0.9, and 0.7 kb, respectively, were detected in 27 strains examined. The same distribution of polymorphisms was observed on digestion of DNAs of these strains with three other enzymes, PvuII, HindIII, and BamHI. Moreover, the same differences in length of allelic restriction fragments were obtained with these restriction enzymes as with PstI. These findings suggested that the polymorphism was caused by insertion or deletion of variable DNA segments in the second intron of the growth hormone gene. Linkage analyses using backcross progeny provided no evidence for close linkage between the restriction fragment length polymorphism locus and 10 other loci examined.

Alleles↗
PubMed1989

A Chinese traditional medicine, juzentaihoto, inhibits the O2- generation by macrophages.

Guinea pig peritoneal macrophages generate superoxide anion (O2-), when stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), phorbol-myristate acetate (PMA) or ovalbumin complex of guinea pig IgG2 antibody (OA gamma 2). These responses were found to be inhibited by a Chinese traditional medicine, Juzentaihoto (JT). When the inhibition was assayed by the use of fMLP as a stimulant, at least one of the substances responsible for the inhibitory activity of JT was identified to be cinnamic acid. An authentic sample of cinnamic acid also inhibited the O2- generation by fMLP-stimulated macrophages. Cinnamic acid, however, did not inhibit the O2- generation, when macrophages were stimulated with PMA and OA gamma 2. These results indicate that a certain cinnamic acid-inhibitable factor may be involved in the intracellular triggering event(s) initiated by fMLP, leading to activation of the respiratory burst reduced nicotinamide adenine dinucleotide phosphate oxidase, but not in those by PMA and OA gamma 2.

Animals↗