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T Shiroishi

Publications and source records attributed to T Shiroishi.

At least 91 records · Page 5Linked to original sources
PubMed1987

Sexual preference of meiotic recombination within the H-2 complex.

The recombination frequency between the H-2K and H-2D marker loci in male mice was measured using heterozygotes that carry the H-2wm7 haplotype derived from the Japanese wild mouse and common H-2 haplotypes derived from inbred mice. Previous mating experiments in which backcross progeny of heterozygous females were screened demonstrated that the H-2wm7 displays marked enhancement of recombination within the H-2 complex. In contrast to recombination in female mice, no enhancement of recombination was observed during male meiosis in the present study. Thus, it appeared that enhancement of recombination is specific to female mice. A genealogical study of recombination indicated that the postmeiotic stage is not involved in the generation of sexual preference of enhancement of recombination, suggesting that the preference is meiotic-drive and that a female-specific mechanism is involved in meiotic recombination mediated by the H-2wm7 haplotype.

Animals↗
PubMed1987

Lethal deletion of the complement component C4 and steroid 21-hydroxylase genes in the mouse H-2 class III region, caused by meiotic recombination.

A recombinant H-2 haplotype, designated aw18, was produced that underwent meiotic recombination in the E alpha (I-E alpha chain)--Slp (sex-limited protein) interval of the H-2 class III region between B10.A (H-2a) and wild-derived B10.MOL-SGR (H-2wm7) strains. It appeared that the H-2aw18 haplotype has a single, recessive, lethal mutation, since homozygotes for H-2aw18 were not detected in progeny generated from the intercross of mice that were heterozygous for this H-2 haplotype. Nine newly established recombinant H-2 haplotypes, which arose from the heterozygous mice that resulted from a cross between common inbred H-2 haplotypes and the aw18 haplotype, allowed us to map the lethal gene to the class III region of the H-2 complex. Southern blot analysis indicated that the aw18 haplotype has a deletion of the C4 gene and a deletion of one of the steroid 21-hydroxylase genes. This result was confirmed by an immunodiffusion test that demonstrated the absence of production of the C4 protein in mice of haplotype H-2aw18. All data that were obtained supported the hypothesis that the meiotic, presumably unequal, recombination between homologous chromosomes of the H-2a and H-2wm7 haplotypes caused the deletion of the C4 and the 21-hydroxylase genes.

Animals↗
PubMed1986

Characterization of newly isolated monoclonal antibodies against MHC of a Japanese wild mouse.

We have already developed nine B10.MOL congenic strains carrying H-2 haplotypes derived from Japanese wild mice, Mus musculus molossinus, with the C57BL/10 genetic background. To obtain monoclonal antibodies against the H-2 antigen of the Japanese wild mouse, we carried out cell fusion using spleen cells from the animal immunized with one of the B10.MOL strains, B10.MOL-SGR (H-2wm7). As a result, 19 hybridomas producing monoclonal antibodies were produced. Analysis with the intra-H-2 recombinants derived from B10.MOL-SGR indicated that 8 of them reacted with the class I and 11 with the class II molecule. The class I antibodies were tested for their cross-reactivities on wild mice and on the panels of standard inbred and B10.MOL strains. Most of the antibodies reacted with both the Japanese wild mice and the other subspecies, including standard inbred, while two antibodies highly specific for the donor H-2K region reacted with only three wild-derived mice, two M. m. molossinus from Anjo and Shizuoka, Japan, and one M. m. domesticus from Pigeon, Canada. In addition, all of the other four antibodies reactive with the K antigen of B10.MOL-SGR also reacted with the same three wild mice. The wild mice belonging to different subspecies might share very similar H-2K antigenic determinants in spite of their genetic and geographical remoteness.

Animals↗
PubMed1985

In vitro mutagenesis of a mouse MHC class I gene for the examination of structure-function relationships.

Oligonucleotide-directed, site-specific mutagenesis has been employed to elucidate the role of individual amino acids on the expression and function of a MHC class I antigen. Two oligonucleotides were synthesized to introduce single amino acid substitutions in the murine H-2Ld gene. The highly conserved glycosylation site at amino acid position 86 was changed from asparagine to lysine to remove the carbohydrate moiety from the first external domain of the H-2 molecule, and the phenylalanine at position 116 was changed to tyrosine, replacing the Ld residue with the Kb type amino acid analogous to Kb mutants: bm5 and bm16 mutants derived from the Kb antigen have the Ld-type residue at this position. The mutant genes were constructed by annealing the mutagenic oligomers to the single stranded H-2Ld gene, followed by chain elongation reaction. The expected mutations were confirmed by DNA sequence determination. The mutant genes were introduced into mouse L cells by DNA-mediated gene transfer. Both mutant genes expressed the antigens on the cell surface, as detected by antibody binding; these antigens were reactive with the cytotoxic T cells specific for the H-2Ld antigen. Detailed examination with 16 monoclonal anti-H-2Ld antibodies revealed that the binding of some antibodies was significantly reduced in the glycosylation mutant, implying a certain contribution of the carbohydrates to the antigenic activity of some determinants. No detectable changes have been observed in the mutant of the substitution at position 116 by the parameters we tested.

Amino Acid Sequence↗
PubMed1984

Role of a disulfide bridge in the immune function of major histocompatibility class I antigen as studied by in vitro mutagenesis.

Polymorphic major histocompatibility class I antigens have highly conserved disulfide bridges in the second and third external domains. To study the role of a disulfide bridge, we have introduced a mutation into the mouse H-2Ld gene by oligonucleotide-directed site-specific mutagenesis, disrupting the disulfide bridge in the second domain of the protein by changing cysteine at amino acid position 101 into serine. Upon introduction of the mutant gene into L cells, the mutant transplantation antigens were synthesized, inserted into the membrane, and displayed on the cell surface, indicating that the disulfide bridge is not essential for surface expression of the H-2 antigen. Binding studies carried out with 16 monoclonal antibodies specific for the H-2Ld antigen showed that most of the allodeterminants are lost or greatly altered in the mutant antigen. Further, almost complete loss of the recognition by H-2Ld-specific alloreactive cytotoxic T cells was observed. These results indicate that polymorphic determinants are dependent on a protein folding pattern dictated by the disulfide bridge. However, two antibodies previously found to react with antigenic sites present in the first and third domains were reactive with the mutant, implying an element of domain independence with respect to the determinants recognized by these antibodies.

Animals↗
PubMed1981

A simplified micro-method for cytotoxicity testing using a flat-type titration plate for the detection of H-2 antigens.

A new micro-method for cytotoxicity testing using a flat-type titration plate has been developed. This micro-method is so simple that it involves no washing and staining procedures. In this method, cell viability is judged on the basis of the refractility change in the lymphocytes seen under the phase-contrast microscope. This micro-method has higher sensitivity and reproducibility than the dye exclusion method and 51Cr-release assay. Fixation of cells with glutaraldehyde and tight covering of the plate allow us to read the result even after 3 weeks. These advantage of the new method enable us to deal with a large number of samples at one time. We also introduce a rapid technique for the preparation of a cell suspension from the lymph node without killing the animal.

Animals↗
PubMed1981

Identification of surface proteins on viable Plasmodium knowlesi merozoites.

Viable merozoites of Plasmodium knowlesi were isolated and the proteins that were labeled on intact merozoites by lactoperoxidase-catalyzed radioiodination were identified. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography of Triton soluble extracts of labeled merozoites demonstrated eight major bands ranging in apparent molecular weight from 150,000 D to 22,000 D. Exposure of intact merozoites to trypsin (10 microgram/ml) for 10 min resulted in the loss of the two highest molecular weight proteins (150,000 D and 105,000 D) and the appearance of two new bands at 70,000 D and 62,000 D. Trypsin treatment under these conditions also removed the receptor(s) for merozoite attachment to erythrocytes. Therefore, these high molecular weight proteins are candidates for the merozoite component that attaches to erythrocytes. There was no evidence that the labeled membrane components were serum or erythrocyte membrane components, two potential contaminants in the preparation. Anti-rhesus erythrocyte antibody did not precipitate labeled merozoite proteins. Furthermore, the immunoprecipitation of labeled merozoite proteins by rhesus anti-merozoite serum was not inhibited by erythrocyte ghosts.

Animals↗
PubMed1981

High frequency fo X-Y chromosome dissociation in primary spermatocytes of F1 hybrids between Japanese wild mice (Mus musculus molossinus) and inbred laboratory mice.

In the hybrids between Japanese wild mice (Mus musculus molossinus) and inbred laboratory mice (BALB/c and B10.BR, which were probably derived from M. m. domesticus), the X and Y chromosomes dissociated precociously at the first meiotic metaphase in some 70% of spermatocytes; that percentage was only 8.9% in inbred laboratory mice and 21.1% in wild mice. X-Y dissociation began at least at early diakinesis and continued during metaphase I (MI). Some autosomes of the hybrid (10.1%) and BALB/c (10.6%) mice also dissociated precociously, but there was no distinctive correlation between X-Y and autosomal dissociation. In B10 or B6 congenic lines with a Y chromosome from wild M. m. molossinus, there was an apparent tendency for the percentage of precocious X-Y dissociation to decrease with an increasing number of back cross generations. Based on these observations we concluded that: 1. the X-Y dissociation found is genetically controlled, perhaps by multiple genes; 2. these genes are located on autosomes and are active only when they are heterozygous; 3. the frequent dissociation of the sex chromosomes neither affects male fertility nor induces non-disjunction of the X and Y chromosomes, though it significantly reduces testes weight.

Animals↗
PubMed1980

Factors affecting the ability of isolated Plasmodium knowlesi merozoites to attach to and invade erythrocytes.

Plasmodium knowlesi merozoites were prepared by the polycarbonate sieving method of Dennis, Mitchell, Butcher & Cohen (1975). Merozoite function was assayed by their attachment to and invasion of rhesus erythrocytes at 37 degrees C. The early merozoites from the culture chamber were the most invasive, although maximum numbers of merozoites appeared later. Merozoites were most stable when incubated at room temperature (23 degrees C). At 37 and 0 degrees C invasiveness rapidly declined to zero. Attachment was rapidly lost at 37 degrees C but was retained at 0 degrees C. Attachment was unchanged in the pH range 6.8--7.9 but invasion was reduced at pH 7.9. The presence of L-fucose, D-galactose, D-glucose, D-mannose, N-acetyl-D-galactosamine or N-acetyl-D-glucosamine did not reduce invasion. Attachment and invasion were greatly reduced or abolished by the presence of 2.5 mM EDTA or EGTA, by lactoperoxidase-catalysed iodination of the merozoites, or by treatment of the merozoites with trypsin at a concentration of 1 micrograms/ml or greater for 10 min at 23 degrees C.

Animals↗
PubMed1980

Genetic regulation of the expression of H-2-K.5 antigen of erythroid cells by H-2K end.

Difference in the amounts of H-2K.5 antigens present on erythrocytes was observed, using quantitative absorption method, among several B 10 congenic strains. However, no such variation was seen on the lymphocytes and lung cells. The variability in the amount of this antigen on the erythrocyte surface was primarily dependent on the haplotype of the H-2K end in the B 10 recombinant strains examined. This suggests that the regulator of H-2 expression on erythrocytes is in this region. Further genetic analysis confirmed that this regulation functions in the cis-position. Finally, the H-2K.5 antigenic activity was expressed on the reticulocytes of all strains tested, but appeared lower in the type 2 group indicating that the regulation begins early in erythropoietic differentiation and eventually results in a complete loss of detectable activity.

Animals↗
PubMed1979

Interaction between cytochalasin B-treated malarial parasites and erythrocytes. Attachment and junction formation.

We have previously demonstrated that invasion of erythrocytes (RBCs) by malaria merozoites follows a sequence: recognition and attachment in an apical orientation associated with widespread deformation of the RBC, junction formation, movement of the junction around the merozoite that brings the merozoite into the invaginated RBC membrane, and sealing of the membrane. In the present paper, we describe a method for blocking invasion at an early stage in the sequence. Cytochalasin-treated merozoites attach specifically to host RBCs, most frequently by the apical region that contains specialized organelles (rhoptries) associated with invasion. The parasite then forms a junction between the apical region and the RBC. Cytochalasin blocks movement of this junction, a later step in invasion. Cytochalasin-treated (Plasmodium knowlesi) merozoites attach to Duffy-negative human RBCs, although these RBCs are resistant to invasion by the parasite. The attachment with these RBCs, however, differs from susceptible RBCs in that there is no junction formation. Therefore the Duffy associated antigen appears to be involved in junction formation, not initial attachment.

Animals↗
PubMed1979

Frequency distribution of histocompatibility-2 antigenic specificities in the Japanese wild mouse genetically remote from the European subspecies.

Fifty-eight Japanese wild mice, Mus musculus molossinus, collected from twenty-eight localities were surveyed for twelve H-2 antigens using the haemagglutination method. Significantly higher frequencies of H-2.3 and H-2.5 specifities and relatively lower frequencies of the other public specificities were observed. This was confirmed by examining four specificities, H-2.3, 5, 13 and 23, in 370 mice. Quantitative absorption of the alloantisera by erythrocytes and spleen lymphocytes of molossinus mouse revealed definite absorption of H-2.3, 5 and 8 antigens, though their antigenic strength was apparently weaker than the controls, B10 congenic mice. Comparative assay of the strength of H-2.5 antigen in either homozygous and heterozygous conditions distinctly eliminated the possibility of gene-dose effect for the reduced strength of the public antigens in molossinus mouse. To explain this, divergence time between molossinus and domesticus was computed based on the allelic frequency data already reported on ten loci in both subspecies. It is roughly 1.5 x 10(6) years, which could allow for the occurrence of considerable genetic changes in many public antigens, except those conserved through selection.

Animals↗
PubMed1978

The Duffy blood group and resistance to Plasmodium vivax in Honduras.

To test the hypothesis that the Duffy blood group negative genotype is a factor in resistance to Plasmodium vivax, we determined the Duffy blood group, the malaria antibodies, and the slide-demonstrated infection rates with P. vivax and P. falciparum of 420 persons living in Nueva Armenia, Honduras. In all, 247 persons were Duffy negative. Demonstrated infections with P. falciparum were almost equally distributed between Duffy-positive (5,8%) and Duffy-negative (4.9%) persons. Similarly, Duffy-positive (25.6%) and Duffy-negative (28.2%) persons had equal proportions of indirect fluorescent antibody test titers suggestive of past or present P. falciparum infection. In contrast, all 14 P. vivax infections were found in Duffy-negative persons. There was no evidence suggesting that Duffy-positive and Duffy-negative persons had different exposures to malaria. The Duffy negative genotype FyFy appears to be a factor in resistance to P. vivax.

Antibodies↗
PubMed1977

Evidence for differences in erythrocyte surface receptors for the malarial parasites, Plasmodium falciparum and Plasmodium knowlesi.

Human erythrocytes lacking various blood group determinants were susceptible to invasion by Plasmodium falciparum including Duffy-negative erythrocytes that are refractory to invasion by Plasmodium knowlesi. Erythrocytes treated with trypsin or neuraminidase had reduced susceptibility of P. falciparum and normal susceptibility to P. knowlesi. Chymotrypsin treatment (0.1 mg/ml) blocked invasion only by P. knowlesi. The differential effect of enzymatic cleavage of determinats from the erythrocyte surface on invasion by these parasites suggests that P. falciparum and P. knowlesi interact with different determinants on the erythrocyte surface.

Chymotrypsin↗
PubMed1977

A simplified method for reading hemagglutinations on a flat-bottom microtitration plate in the mouse H-2 assay.

Kaliss' method for determining hemagglutination titer of mouse alloantiserum was modified to a simpler form. It became possible to read the hemagglutination directly on a flat-bottom microtitration plate using an inverted type microscope. Sensitivity of the modified method was almost the same as that of the original one. This method seems to be useful especially for the larger scale assay of H-2 specificities.

Animals↗
PubMed1977

The Duffy blood group determinants: their role in the susceptibility of human and animal erythrocytes to Plasmodium knowlesi malaria.

Duffy blood group negative erythrocytes from blacks are refractory to invasion by Plasmodium knowlesi merozoites in vitro, and blacks with this genotype are resistant to infection by P. vivax in vivo. In order to evaluate in a direct manner the role of Duffy blood group determinants in invasion by P. knowlesi merozoites, we studied erythrocytes from three rare non-black Duffy negative individuals, Fy(a-b-), in whom the Duffy negative phenotype probably represents a mutation and not the introduction of the black Fy gene. These cells were resistant to invasion by P. knowlesi in vitro indicating that resistance to invasion is mediated by the FyFy genotype and not another closely linked factor. The erythrocyte receptors for invasion, however, may not be the Fya or Fyb Duffy antigens themselves, or at least not restricted to these determinants, since refractory Duffy negative human erythrocytes were invaded after treatment with trypsin or neuraminidase although these enzyme-treated cells still lacked Fy a and Fy b determinants. Furthermore, new world monkey erythrocytes and chymotrypsinized chimpanzee and kra monkey erythrocytes were invaded, although there was no serologic evidence of Fya or Fyb determinants on these cells.

Animals↗