Biomedical subjects

T Imamichi

Publications and source records attributed to T Imamichi.

76 records · Page 5Linked to original sources

PubMedDate not supplied

Congenital osteochondrodysplasia with systemic subcutaneous edema (ocd/ocd): a new lethal autosomal recessive mutant of the rat.

The inheritance of a new lethal mutant rate showing congenital osteochondrodysplasia with systemic subcutaneous edema (ocd for the gene symbol) was examined by crossings between the carriers and between F1s derived from the carrier x Long-Evans crossing. The ratio of the affected to phenotypically normal was 276:89 in pups derived from the crossings between the carriers and 83:17 in those at the LE-F2 generation derived from the proven carriers of the LE-F1 animals, thus showing that the ratio is 3:1. The female:male ratio was 47:42 in the affected and 133:143 in the phenotypically normal pups, showing the sex ratio is 1:1, irrespective of the affected or phenotypically normal. The ratio of affected:carrier:noncarrier was 26:58:27 in littermates derived from the crossings between the carriers, showing the ratio is 1:2:1. The results fitted well to the hypothesis that the inheritance is a single autosomal recessive trait. Independence of the gene from linkage group I was also revealed, because the ratio of colored to albino was 14:3 and 65:18 in affected and phenotypically normal pups at the LE-F2 generation, respectively, which fitted to the ratio of 3:1.

Animals↗

PubMedDate not supplied

Male hypogonadism as a candidate of deficiency of postnatal testicular growth or differentiating factor(s): a new autosomal recessive mutation in the rat.

A new rat mutant showing severe male hypogonadism (hgn for the gene symbol) was found and isolated from the hereditary hydronephrosis rat strain originating from the Wistar-Imamichi rat. The affected rats have very tiny testes that weigh 26 mg in the adult, and contain small numbers of seminiferous tubules with degenerated Sertoli cells. It is difficult to identify the gonocyte in the seminiferous tubules in the mutant testis. Very small male accessory sex organs are all present in the mutant. The number of chromosomes is 42 (40A + XY). The structure of each chromosome is normal, showing that the mutant has male sex genes. Thus, it was considered that this status is not due to either lack of the H-Y antigen or Muellerian inhibiting factor or expression of the Tfm. By analyzing the pedigree of the matings producing the mutant, it was concluded that the status was expressed only in the male, but inherited with a single autosomal recessive trait with existence of the phenotypically normal fertile female recessive homozygote. A possible deficiency of certain known or unknown testicular growth or differentiating factor(s) in the mutant is suggested.

Aging↗

PubMedDate not supplied

Different abilities of two types of Fc gamma receptor on guinea-pig macrophages to trigger the phosphatidylinositol turnover.

When exposed to hen ovalbumin (OA) complexes of IgG antibodies, guinea-pig macrophages were found to augment the phosphatidylinositol (PI) turnover. This response depended on the IgG isotype of antibodies used; OA complex of IgG2 antibody (OA gamma 2) triggered it about 3 times more effectively than did OA complex of IgG1 antibody (OA gamma 1). The inhibition experiments with monoclonal antibodies to Fc gamma 1/gamma 2R and Fc gamma 2R showed that Fc gamma 2R triggered activation of the PI turnover more intensively than did Fc gamma 1/gamma 2R. The same results were also obtained by the cross-linking of Fc gamma 2Rs or Fc gamma 1/gamma 2Rs by a combination of anti-mouse IgG F(ab')2 and anti-Fc gamma 2R F(ab')2 or anti-Fc gamma 1/gamma 2R F(ab')2. 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 the response was found to be much greater than that of Fc gamma 1/gamma 2R. Despite this difference, neither the activity of Fc gamma 2R nor that of Fc gamma 1/gamma 2R to augment the PI turnover were affected by depletion of the intracellular Ca2+ by incubating the cells with Ionomycin and EGTA, and also by the treatment with pertussis toxin.

Animals↗

PubMedDate not supplied

Functions of two types of Fc gamma receptor on guinea-pig macrophages in immune complex-induced arachidonic acid release.

Guinea-pig macrophages respond to ovalbumin (OA) complexes of IgG antibodies with the extracellular release of arachidonic acid (AA). The AA release by OA complex of IgG2 antibody (OA gamma 2) was found to occur more intensively than did that by OA complex of IgG2 antibody (OA gamma 1). To clarify the roles of the Fc gamma receptor (Fc gamma R) for IgG2 alone (Fc gamma 2R) and that for both IgG1 and IgG2 (Fc gamma 1/gamma 2R) in these responses, the effects of Fab's of monoclonal anti-Fc gamma 2R and anti-Fc gamma 1/gamma 2R antibodies were examined. Anti-Fc gamma 1/gamma 2R Fab' inhibited completely the response to OA gamma 1. The response to OA gamma 2, on the other hand, was not inhibited by anti-Fc gamma 1/gamma 2R Fab', but by anti-Fc gamma 2R Fab'. By cross-linking of the Fc gamma Rs, the ability of Fc gamma 2R to trigger the AA release was found to be 2-3 times greater than its Fc gamma 1/gamma 2R counterpart. The Fc gamma 1/gamma 2R-mediated response to OA gamma 1 was completely inhibited with EGTA. In contrast, the Fc gamma 2R-mediated response to OA gamma 2 was not affected at all with EGTA, though it disappeared on depletion of the intracellular Ca2+ of macrophages with EGTA and Ionomycin. In conclusion, the mechanisms of Fc gamma 1/gamma 2R- and Fc gamma 2R-mediated signal transduction leading to the AA release differ from each other in the dependency upon the Ca influx.

Animals↗