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R Kominami

Publications and source records attributed to R Kominami.

At least 73 records · Page 4Linked to original sources
PubMed1995

Dose-response of a radiation induction of a germline mutation at a hypervariable mouse minisatellite locus.

Dose-response of an induction of a germline mutation was studied at a hypervariable mouse minisatellite locus, Ms6hm, which consists of tandem repeats of a sequence motif GGGCA. Male C3H/HeN mice were exposed to various doses of 60Co gamma-ray and mated with unirradiated C57BL/6N female mice. Matings were done at various time after irradiation to assess the effects of radiation on spermatozoa, spermatids and spermatogonia. DNA samples of F1 offsprings were analysed by Southern blotting for the repeat length mutation at the Ms6hm locus. The mutation frequency per gamete of the paternal allele was 9.1% for the unirradiated control group. The spermatids stage was most sensitive to radiation and a statistically significant dose-response was observed. The mutation frequency of the paternal allele in F1 mice increased to 22% for 1 Gy, 28% for 2 Gy, and 28% for 3 Gy. The spermatogonia stage was less sensitive to radiation, and the mutation frequencies of the paternal allele were 14% for 2 Gy, and 16% for 3 Gy. The spermatozoa stage germ cells were also less sensitive and the frequency of mutation of the paternal allele increased to 14% for 3 Gy. However, these increases were statistically not significant. Possible mechanisms of radiation induction of germline mutation at the hypervariable minisatellite locus will be discussed.

Alleles↗
PubMed1995

Mutational and LOH analyses of p53 alleles in colon tumors induced by 1,2-dimethylhydrazine in F1 hybrid mice.

To elucidate the role of p53 in colon tumorigenesis in mice, we examined allele loss and mutational alteration of the p53 gene in colon tumors induced by 1,2-dimethylhydrazine (DMH) in F1 hybrid mice. Intragenic polymorphism of the p53 gene among parental strains enabled us to assess allele loss of the p53 gene and also to determine parental origin of mutated and/or lost alleles. Allele loss was detected in two of 163 tumors heterozygous for the p53 gene. Polymerase chain reaction-single-strand conformation polymorphism analysis of p53 exons 5-8 revealed 33 mutations in 20 of 182 colon tumors, the incidence being lower than that in human colon cancers. The majority of these mutations were of transition type: G:A transitions at non-CpG sites were most prevalent, while those at CpG sites were less common. Distribution of the mutations along p53 amino acid sequence revealed a difference in the location of 'hot spots' between mice and humans. Incidence of p53 alterations did not differ among alleles of different parental origins, suggesting that genetic changes in DMH-induced mouse colon tumors had occurred independently of parental origin and DMH susceptibility. Detailed analysis of p53 mutations on each allele revealed intratumoral heterogeneity in mouse colon tumors. The low incidence of p53 mutations and rare allele loss suggest that p53 alteration plays only a minor role in colon tumorigenesis in mice.

1,2-Dimethylhydrazine↗
PubMed1994

A functional site of the GTPase-associated center within 28S ribosomal RNA probed with an anti-RNA autoantibody.

An anti-RNA autoantibody (anti-28S) was employed to identify structural and functional elements characteristic of a domain termed the 'GTPase center' in eukaryotic 28S ribosomal RNA. This antibody, an inhibitor of ribosome-associated GTP hydrolysis, has a unique property: it binds to the RNA domain of eukaryotes but not to that of prokaryotes. The antibody binding occurred in the presence of Mg2+ and protected from chemical modification three conserved bases (U1958, G1960 and A1990) and the base G1959 which is replaced by A in prokaryotic 23S rRNA (A1067 in Escherichia coli). In vitro substitution of G1959 to A drastically weakened the antibody binding, and the reciprocal substitution, A1067-->G of the E.coli domain conferred the binding ability. This suggests that the G base determines the specificity of antibody binding. The G1959 was also protected by the association of ribosomes with elongation factor EF-2. The result, together with protection of E.coli base A1067 by EFG [D.Moazed, I.M. Robertson and H.F. Noller (1988) Nature, 334, 362-364], suggests that the position of G1959 in eukaryotes and A1067 in prokaryotes constitutes at least part of the factor binding site irrespective of the base replacement during evolution.

Animals↗
PubMed1994

Lymphadenopathy induced by the cooperation between lprcg and gld genes is of lpr but not of gld phenotype.

Mice homozygous for the lpr (lymphoproliferation), lprcg or gld (generalized lymphoproliferative disease) mutation develop strikingly similar lymphadenopathy with expansion of B220+ CD4- CD8- double-negative (DN) T cells and autoimmunity. To elucidate the roles of bone marrow (BM) and lymph node (LN) in lymphoproliferation, BM and LN were transplanted simultaneously into normal or +/+ mice in various genotype combinations. In lpr/lpr or lprcg/lprcg BM recipients grafted lpr/lpr and lprcg/lprcg LN swelled but +/+ and gld/gld LN atrophied. In gld/gld BM recipients all of LN swelled regardless of genotype. Thus, lpr and lprcg are phenotypically different from gld in the interaction of BM-derived DN T cells and +/+ LN. Compared with lpr the lprcg gene differs in its ability to complement with gld in induction of lymphadenopathy. To determine whether lymphoproliferation induced by the cooperation between lprcg and gld is of lpr or gld phenotype, LN of various genotypes were implanted into double heterozygous lprcg/+, gld/+ mice. Grafted lpr/lpr and lprcg/lprcg LN swelled but +/+ and gld/gld LN atrophied, indicating that it is of lpr phenotype. Moreover, grafted lprcg/+ LN swelled but lpr/+ LN atrophied, indicating that, in the heterozygous state, lprcg is phenotypically different from lpr as it allows for LN accumulation of DN T cells induced by lprcg-gld cooperation.

Animals↗
PubMed1994

2-Hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine induction of recombinational mutations in mammalian cell lines as detected by DNA fingerprinting.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the most abundant mutagenic heterocyclic amine in cooked foods. Two mouse tumor cell lines, BMT11 and FM3A, were exposed to its proximate form, 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-OH-PhIP). Fifty-six subclones of BMT11 and 39 subclones of FM3A were isolated and analyzed by DNA fingerprinting. Treatment with 10-20 microM N-OH-PhIP gave rise to extra bands or shifted bands, but treatment without N-OH-PhIP did not. This suggests that mutations resulting from recombination were induced. The mutation frequencies were 21-53% and 22-35% for BMT11 and FM3A, respectively. These findings suggest that PhIP induces recombinational mutations.

Animals↗
PubMed1994

Methylation imprinting was observed of mouse mo-2 macrosatellite on the pseudoautosomal region but not on chromosome 9.

Mouse mo-2 macrosatellites consisting of 31-bp tandem repeat units are mainly located at two loci in the C57BL/6 genome, one being at the centromere-distal telomeric region of chromosome 9 and the other at the pseudoautosomal (PA) region of chromosomes X and Y. The two clusters constitute approximately 300 kb and 150 kb, respectively. Southern analysis of a methylation-sensitive enzyme, HpaII-digested DNA showed that the mo-2 macrosatellites are detected as more than 30 polymorphic bands. Comparison of those bands between reciprocally crossed F1 mice revealed that approximately 20% of the allele-specific fragments exhibit different band intensities depending on the sex of the parent of origin. The differential methylation is observed in the mo-2 macrosatellite on the PA region but not in that on chromosome 9. Several fragments including the 3.4-kb fragment without internal HpaII site are more clearly detected when paternally derived, suggesting that the male-derived macrosatellite is undermethylated. Interestingly, the difference is much more remarkable in inter-subspecific F1 mice between C57BL/6 and MSM than F1 between C57BL/6 and C3H/He. This suggests the presence of a modifier(s) that affect(s) the methylation of mo-2 in the MSM genome.

Animals↗
PubMed1994

Radiation induction of germline mutation at a hypervariable mouse minisatellite locus.

Paternal 60Co gamma-irradiation was tested for the induction of germline mutation at the mouse hypervariable minisatellite locus, Ms6hm. Male C3H/HeN mice were exposed to 3 Gy 60Co gamma-ray and mated with C57BL/6N females. Matings were made at 1-7, 15-21 and 71-77 days post-treatment to test spermatozoa, spermatids and spermatogonia stages. Reciprocal crosses were also made with irradiated C57BL/6N males. Southern analysis was carried out on DNA from parents and F1 mice. The paternal mutation frequencies per gamete of the Ms6hm locus were 8.3, 13, 28 and 15% for the C3H/HeN control, exposed spermatozoa, spermatids and spermatogonia stages, respectively. The paternal mutation frequencies per gamete were 7.7% for the C57BL/6N control and 13% for the C57BL/6N exposed spermatozoa stage. The increase in the paternal germline mutation frequency was statistically significant for C3H/HeN spermatids irradiation (p < 0.005). The induced mutation frequencies were of the order of 10(-1), and was too high to be accounted for by the direct action of radiation on the locus. These results suggest the presence of a previously unexpected mechanism of radiation induction of germline mutation. In addition, we demonstrate that the hypervariable minisatellite locus can serve as a sensitive monitor for genetic damages to germline cells.

Animals↗
PubMed1994

Novel mouse microsatellites: primer sequences and chromosomal location.

Sixty-nine sequences containing microsatellites were determined by analysis of clones from a pUC118 library of total genomic mouse DNA. These sequences were examined for size variation using polymerase chain reaction and gel electrophoresis. Fifty-one of them showed allelic variations between C57BL/6 and MSM, the two strains used for genetic mapping. Hence, their chromosomal location was determined using a panel consisting of 131 backcross mice that had been typed with 85 anchor loci. The microsatellites were distributed to most chromosomes except for chromosomes 16 and 19. These novel markers with defined locations are useful in linkage and genome mapping studies.

Animals↗
PubMed1994

Difference in allelic expression of genes probably associated with tumor progression in murine fibrosarcomas and cell lines.

Allelic expression was examined by single-strand conformation polymorphism analysis in murine fibrosarcomas from inter-subspecific F1 mice between C57BL/6 and MSM. Ten genes encoding p53, mdm2, E-cadherin, 72 kD metalloproteinase and its inhibitor (Timp2), thymidine kinase and four glucose transporters (Gluts) were examined. These genes were chosen because of their probable association with tumor development and progression. In some of the tumors and cell lines, p53, E-cadherin and Glut3 genes showed remarkable differences in allelic expression, one allele being poorly expressed. The allele-specificity persisted in nine cell lines obtained by repeated transplantations from one tumor. These results suggest that expression of some genes is allele-specific in tumor cells and the pattern of specificity is stable. Such a decrease or a loss of expression in one of the alleles may be functionally equivalent to the loss of heterozygosity of the gene, and therefore this may confer malignant properties on tumor cells. It is also suggested that differential expression of two alleles is a common event in tumor cells.

Alleles↗
PubMed1994

Serological association of lupus autoantibodies to a limited functional domain of 28S ribosomal RNA and to the ribosomal proteins bound to the domain.

Site-specific anti-RNA antibodies were sought in 120 sera of patients with autoimmune diseases by ribonuclease-protection assay using six fragments covering 28S ribosomal RNA (rRNA) as antigens. Fifteen of 90 sera from patients with systemic lupus erythematosus (SLE), but none of 30 sera of the other autoimmune diseases, provided a 60 nucleotide fragment within a region termed the 'GTPase domain' of 28S rRNA. These sera had potency to precipitate 0.42-69.3 nmol of the RNA domain per ml serum, which was higher than 15 control sera of healthy donors. No other specific antigenic site was detected in 28S rRNA under conditions used. All of the 15 sera having this anti-RNA antibody showed reactivity to ribosomal P proteins (anti-P), and two of them contained an additional antibody to ribosomal protein L12. These results suggested a strong association of the production of these three antibodies. Since P and L12 proteins form a stable complex with the GTPase domain, this serological association may result from an immune response to epitopes clustered on a single RNA-protein complex domain in ribosomes.

Autoantibodies↗
PubMed1994

A novel nonreceptor tyrosine kinase, Srm: cloning and targeted disruption.

We have isolated a novel nonreceptor tyrosine kinase, Srm, that maps to the distal end of chromosome 2. It has SH2, SH2', and SH3 domains and a tyrosine residue for autophosphorylation in the kinase domain but lacks an N-terminal glycine for myristylation and a C-terminal tyrosine which, when phosphorylated, suppresses kinase activity. These are structural features of the recently identified Tec family of nonreceptor tyrosine kinases. The Srm N-terminal unique domain, however, lacks the structural characteristics of the Tec family kinases, and the sequence similarity is highest to Src in the SH region. The expression of two transcripts is rather ubiquitous and changes according to tissue and developmental stage. Mutant mice were generated by gene targeting in embryonic stem cells but displayed no apparent phenotype as in mutant mice expressing Src family kinases. These results suggest that Srm constitutes a new family of nonreceptor tyrosine kinases that may be redundant in function.

Amino Acid Sequence↗
PubMed1994

Mutation of the p53 gene in gallbladder cancer.

Genetic alteration of the p53 gene was examined in tissue specimens of primary gallbladder cancer (GBC) using PCR-single strand conformation polymorphism (SSCP) and direct sequencing analyses. The p53 gene mutation was detected in five of the 16 GBC cases examined (31%). All five cases showed single point mutations; four were mutations resulting in amino acid substitution and the other was one base-pair deletion. Of the five mutations detected, four occurred at evolutionarily conserved regions and the remaining one at a well conserved region among species. Our result is similar to those of previous reports for various human cancers in mutation scattering over four of the five conserved domains.

Adult↗
PubMed1994

Allelic losses and metastatic ability of mouse tumor cell clones derived from a heterozygous mouse.

Some chromosomal or subchromosomal deletions observed in a variety of cancer cells may be related with metastatic properties of the tumor cells. Thus, relationship between allelic losses and metastatic ability is here investigated of ten in vitro clones obtained from 505 cells that are derived from a fibrosarcoma induced in a F1 mouse between C3H and C57BL strains. Allelic loss was examined using 61 microsatellite markers spanning all autosomes and deletions of various loci were observed in all of the clones. One clone showed a metastatic ability higher than the parental 505 cells and the other clones. This particular clone specifically lost a chromosome 16 derived from C57BL, suggesting an association of this chromosome deletion with the metastatic ability. Consistently, examination of metastatic nodules derived from 505 cells and one in vitro clone showed that the cells with deletion of the C57BL chromosome increased in number during metastasis. These results suggest that mouse chromosome 16 may harbor a gene(s) involved in metastasis.

Alleles↗
PubMed1994

Sex typing of forensic DNA samples using male- and female-specific probes.

Forensic DNA samples have been examined to ascertain the feasibility of a sex-typing procedure that we have recently developed. This uses two sets of primers complementary to the DXZ4 and SRY genes for polymerase chain reaction (PCR). PCR target in the DXZ4, an 80-bp sequence within the 130-bp fragment specific to females, is generated from inactive chromosome X by the DNA digestion with a methylation-sensitive restriction enzyme, HpaII. Therefore, the DXZ4 amplification and subsequent agarose gel electrophoresis detect the 80-bp fragment from female DNA. On the other hand, the SRY probe identifies a male-specific sequence on chromosome Y. Testing DNAs from fresh Turner's blood and from postmortem tissues exhibited band-signals confirming the sex identification. Degraded DNAs isolated from severely decomposed specimens were also identifiable when high-molecular-weight DNA was isolated before the assay. This demonstrates the usefulness of this method in forensic identification.

Base Sequence↗
PubMed1994

[Research on the correlation between DNA recombinational mutation and cancer malignancy in human colon cancers].

The mutagenicity of quercetin, a flavonoid, was examined by means of DNA fingerprint analysis using the Pc-1 and Pc-2 minisatellite probes that efficiently detect mutations due to recombination. Treatment of FM3A and BMT-11 tumor cells with 55 microM quercetin resulted in gain and loss of bands in the fingerprints in both cell lines. The frequencies of the clones having undergone mutation were 9/26 and 2/11, using Pc-1 probe, respectively, in the two lines. These results seem to provide a molecular basis for the phenotypic variations of BMT-11 tumor cells induced by quercetin, giving direct evidence of genetic instability of the tumor cells. Moreover, we examined for a possible correlation between frequencies of DNA recombinational mutations and cancer malignancy in human colon cancers. DNA of four human colon cancer tissues and corresponding peripheral blood cells were prepared, respectively, and examined by DNA fingerprint analysis using hPc-1 polymorphic minisatellite probe. These four specimens exhibited no extra-bands resulting from recombination and/or DNA slippage at present. We would explain how the prognosis of cancer patients is related to frequencies of DNA recombinational mutation.

Aged↗
PubMed1993

A variant family of mouse minor satellite located on the centromeric region of chromosome 2.

A variant sequence of minor satellite that exhibits a polymorphism in strains and a subspecies of the mouse by pulsed-field gel analysis has been cloned. A segregation study using intrasubspecific backcross mice reveals that the variant maps to the centromeric region of chromosome 2. A long-range physical analysis of the region shows that the variant family is probably located between the proximal telomere and the major satellite. The sequence probe provides an important marker of the chromosome 2-specific centromere.

Animals↗