PubMed Health⌕ Search

Biomedical subjects

L B Barnett

Publications and source records attributed to L B Barnett.

At least 19 recordsLinked to original sources
PubMed1992

ENU mutagenesis in the mouse electrophoretic specific-locus test. 2. Mutational studies of mature oocytes.

Experiments were conducted using the biochemical specific-locus test to assess the mutagenicity of N-ethyl-N-nitrosourea (ENU) in mature oocytes of mice. C57Bl/6J females were treated with 100 mg/kg ENU by intraperitoneal injection and mated to untreated DBA males for 1 week following treatment. 1447 progeny were screened for evidence of mutations affecting the electrophoretic mobility of 32 different proteins; two mutants were detected by electrophoretic analyses. These results provide evidence that ENU is a germ-cell mutagen in mouse mature oocytes, although the frequency of mutants is somewhat lower than that obtained from spermatogonia treated with the same dose.

Animals↗
PubMed1992

Ethylene dibromide: negative results with the mouse dominant lethal assay and the electrophoretic specific-locus test.

Ethylene dibromide (1,2-dibromoethane; EDB) was tested for the induction of dominant lethal and electrophoretically-detectable specific-locus mutations in the germ cells of DBA/2J male mice. Males were treated with a single intraperitoneal injection of 100 mg/kg EDB and mated to two C57BL/6J females. In the dominant lethal assay, matings were carried out to measure the effect of EDB on meiotic and postmeiotic stages; germ cells representing spermatogonial stem cells were analyzed in the electrophoretic specific-locus test. Neither of these germ cell tests produced any evidence that EDB is a germ cell mutagen. It appears from these data and those reported in the literature that EDB, a genotoxic carcinogen that affects male fertility in some mammalian species, is not mutagenic in the germ cells of the male mouse.

Animals↗
PubMed1992

A malic enzyme probe detects cross-hybridizing sequences closely linked to loci encoding other metabolic enzymes.

The cytoplasmic malic enzyme (Mod-1) catalyzes the oxidative decarboxylation of malate: malate + NADP+----pyruvate + CO2 + NADPH + H+. Using a cDNA clone of Mod-1 as a probe, two new DNA markers not at the Mod-1 locus (restriction fragment length polymorphisms, RFLP) were detected by Southern blot analysis that showed extensive homology to Mod-1 sequences. Linkage of each restriction fragment length polymorphism to loci other than Mod-1 was assessed using the BXD (C57BL/6J x DBA/2J) recombinant inbred strains and confirmed by backcrosses. One polymorphic site, designated D9Rti1, was found to be closely linked to the phosphoglucomutase (Pgm-3) locus on Chromosome 9. The other hybridization site, designated D1Rti2, was closely linked to the isocitrate dehydrogenase (Idh-1) locus on Chromosome 1. The data presented imply that Mod-1 homologous sequences are tightly linked to three different metabolic enzymes.

Animals↗
PubMed1991

ENU mutagenesis in the mouse electrophoretic specific-locus test, 1. Dose-response relationship of electrophoretically-detected mutations arising from mouse spermatogonia treated with ethylnitrosourea.

The mouse electrophoretic specific-locus test for induced germ-cell mutations, was used to determine the response of spermatogonial stem cells to a series of doses of the germ cell mutagen N-ethyl-N-nitrosourea (ENU). Male DBA/2J and C57B1/6J mice were treated with doses of 50, 100, 200 or 250 mg/kg ENU and their progeny screened for electrophoretically-detectable mutations at 32 separate loci. As expected, increasing doses of ENU led to increasing mutant frequencies. The differences in mutant frequencies between treated DBA/2J and C57B1/6J males were not statistically significant.

Alleles↗
PubMed1990

A new dominant neurological mutant induced in the mouse by ethylene oxide.

This paper describes a dominant neurological mutation identified among the progeny of a male parent treated with ethylene oxide. The defects observed in the heterozygous mutant include: head tossing, poor limb coordination, and corneal clouding. Both the behavior and ocular manifestations of the mutant syndrome worsen progressively as the affected animals grow older. The mutant animals swim poorly, although they do orient themselves in reference to the surface of the water. Breeding in general is poor. Very small litter sizes result when heterozygous animals of either sex are mated to normal mice. Many male carriers are functionally sterile. All mutant animals had abnormal karyotypes. The original carrier mouse had a translocation between Chromosomes 4 and 17, which was also present in all but one mutant animal. The exceptional animal, which showed all mutant behavioral characteristics, had 41 chromosomes which included two normal 4 and 17 homologs and the small 4(17) translocation chromosome. Karyotypes of unaffected siblings of mutants were normal. Because the small translocation chromosome appears to be inseparably associated with the mutant phenotype, we have named the mutation translocation induced circling mutation symbol, Tim.

Age Factors↗
PubMed1990

Biochemical and molecular analysis of spontaneous and induced mutations at the mouse Mod-1 locus.

We have analyzed five Mod-1 (malic enzyme) mutants at the molecular and biochemical level. Four of these mutants, three electrophoretic variants and one null mutant, were induced by ethylnitrosourea (ENU). Another null mutant was the result of a spontaneous mutation. All of these mutations were heritable in a Mendelian fashion and viable in the homozygous condition. Restriction endonuclease and Southern blot analysis revealed that the spontaneous null mutant possessed an altered restriction fragment banding pattern. All of the ENU-induced mutants possessed normal restriction fragment banding patterns. All 5 mutants produced normal levels of Mod-1-specific mRNA. Only the spontaneous null mutant produced mRNA with altered size, which was consistent with the altered DNA-banding pattern. MOD-1 enzyme activity levels were normal in the three ENU-induced mutants with altered electrophoretic mobility. Enzyme activity was significantly lower than normal in tissues from animals homozygous for the null alleles, however, using Western blot analysis, low but significant levels of MOD-1 protein in Mod-1 null homozygotes were detected.

Animals↗
PubMed1988

N-ethyl-N-nitrosourea-induced null mutation at the mouse Car-2 locus: an animal model for human carbonic anhydrase II deficiency syndrome.

Electrophoretic screening of (C57BL/6J x DBA/2J)F1 progeny of male mice treated with N-ethyl-N-nitrosourea revealed a mouse that lacked the paternal carbonic anhydrase II (CA II). Breeding tests showed that this trait was heritable and due to a null mutation at the Car-2 locus on chromosome 3. Like humans with the same inherited enzyme defect, animals homozygous for the new null allele are runted and have renal tubular acidosis. However, the prominent osteopetrosis found in humans with CA II deficiency could not be detected even in very old homozygous null mice. A molecular analysis of the deficient mice shows that the mutant gene is not deleted and is transcribed. The CA II protein, which is normally expressed in most tissues, could not be detected by immunodiffusion analysis in any tissues of the CA II-deficient mice, suggesting a nonsense or a missense mutation at the Car-2 locus.

Alleles↗
PubMed1986

Dominant visible and electrophoretically expressed mutations induced in male mice exposed to ethylene oxide by inhalation.

The offspring of DBA/2J male mice exposed to ethylene oxide (EtO) by inhalation had an increased incidence of both dominant visible and electrophoretically detected mutations over that found in control populations. The progeny at risk were obtained from matings during the exposure period and were the products of germ cells that were exposed throughout the entire spermatogenic process. The results reported here suggest that male germ cells repeatedly exposed to EtO during spermatogenesis are susceptible to EtO-induced transmissible damage.

Administration, Inhalation↗
PubMed1986

Linkage of Pep-2 and Apk on mouse chromosome 10.

An ethylnitrosourea (ENU)-induced electrophoretic variant of mouse PEP-2, a tripeptidase, has been used to determine the location of the structural gene on chromosome 10. Gene order and recombination frequencies were estimated as Apk-21.8 +/- 3.9%-Pep-2-3.7 +/- 2.1%-Sl. Methods for rapid determination of Apk and Pep-2 alleles by cellulose acetate electrophoresis and a valuable linkage testing stock carrying the unique Apkm and Pep-2b alleles are described.

Acid Phosphatase↗
PubMed1985

A mutation in the beta-globin gene detected in the progeny of a female mouse treated with ethylnitrosourea.

A mouse with a variant hemoglobin was discovered during electrophoretic screening of (C57BL/6J X DBA/2J)F1 progeny of females treated with ethylnitrosourea. The variant trait was transmitted as a simple Mendelian alternate at the Hbb locus in all crosses except those involving the original carrier of the mutation. The proband mouse which received the mutation directly from the mutagen-treated parent was a germinal mosaic for the mutant and normal Hbbs alleles. The mutant allele was designated Hbbs2. The mutant haplotype specifies both an electrophoretically fast hemoglobin band and a hemoglobin band in the normal beta single hemoglobin position. Thus, the mutation has altered one of the tandemly duplicated genes at the Hbbs locus. A comparison of the relative concentrations of the two hemoglobins in Hbbs2 mice demonstrates preferential expression of the mutant gene, possibly analogous to the enhanced expression of Hbbdmaj in the Hbbd haplotype. Analysis of the amino acid sequence of the variant beta-globin revealed that the valine at position 60 was changed to glutamic acid. The simplest mutation mechanism for such an alteration is an A X T----T X A transversion.

Animals↗
PubMed1983

A mouse model for beta-thalassemia.

A mutation that produces an absolute deficiency of normal beta-major globin polypeptides has been recovered from a DBA/2J male mouse. Most mice homozygous for the deficiency survived to adulthood and reproduced but were smaller at birth than their littermates and demonstrated a hypochromic, microcytic anemia with severe anisocytosis, poikilocytosis, and reticulocytosis and the presence of inclusion bodies in a high proportion of circulating erythrocytes. Mice heterozygous for the deficiency demonstrated a mild reticulocytosis but were not clinically anemic. Analysis of globin chain synthesis in vitro by 3H-leucine incorporation revealed that beta-globin synthesis was nearly normal (95%) in heterozygotes and about 75% of normal in deficiency homozygotes. Molecular characterization of the mutation by restriction analysis revealed a deletion of about 3.3 kb of DNA, including regulatory sequences and all coding blocks for beta-major globin. Based on genetic and hematological criteria, mice homozygous for the mutant allele, designated Hbbth-1, represent the first animal model of beta-thalassemia (Cooley's anemia), a severe genetic disease of humans.

Animals↗
PubMed1981

A null mutation at the mouse Phosphoglucomutase-1 locus and a new locus Pgm-3.

A null mutation at the phosphoglucomutase locus (Pgm-1) was discovered by electrophoretic analysis of the inbred mouse strain C57BL/6J. The null allele (Pgm-1n) was shown to segregate as a Mendelian unit alternative to the Pgm-1a and Pgm-1b alleles. Mice expressing the Pgm-1n allele, either in the heterozygous or homozygous state, are viable, healthy, and fertile. The occurrence of the Pgm-1n mutant revealed a previously unreported genetic locus (Pgm-3) that controls the expression of a third phosphoglucomutase. Two electrophoretically expressed alleles of Pgm-3 (inherited without dominance) are found in the inbred mouse strains C57BL/6J and DBA/2J. Linkage observed between the Pgm-3 locus, the dilute locus (d) and the cytoplasmic malic enzyme locus (Mod-1) has allowed assignment of the Pgm-3 locus to chromosome 9. A striking tissue specific expression of Pgm-1 and Pgm-3 was observed. Products of the Pgm-3 locus were detected in kidney, testes, brain, and heart. In contrast, Pgm-1 controlled isozymes were present in kidney, spleen, ovaries, and erythrocytes.

Alleles↗
PubMed1981

Genetic control of antibody production to myelin basic protein in mice.

Experimental allergic encephalomyelitis (EAE) is a disease produced by inoculation of myelin basic protein (BP) into susceptible animals. Data in this report link the production of anti-BP antibody to the murine H-2 histocompatibility background. H-2k and H-2a animals produce high levels of anti-BP antibodies as measuring during both primary and secondary immune responses. Strains with H-2b,d,p,q,s haplotypes are poor responders after primary immunization; however some H-2s and H-2d animals showed an increase in antibody after boosting. The use of M. tuberculosis instead of M. butyricum resulted in greater antibody production in H-2d strains. The response observed in 4 congenic pairs of mice support the association between antibody formation and the H-2 complex. Experiments with recombination inbred strains indicate that responsible genes reside in the I-A region of the H-2 complex.

Animals↗
PubMed1980

Neuropathology of experimental allergic encephalomyelitis in inbred strains of mice.

Ten inbred strains of mice were tested for their susceptibility to experimental allergic encephalomyelitis (EAE) after sensitization with mouse spinal cord in complete Freund's adjuvant followed by booster injections of Bordetella pertussis. The results extended previous findings in that not all susceptible mice possessed the H-2s haplotype, but mice with an H-2q background (DBA1/J strain) were also susceptible. Neuropathologic examination of experimental allergic encephalomyelitis in the mouse showed that from strain to strain, the condition was similar. The over-all pathologic picture was somewhat midway between that seen in other species sensitized with whole nervous tissue in complex Freund's adjuvant and hyperacute experimental allergic encephalomyelitis in rats similarly sensitized but with the addition of B. pertussis. Perivascular cuffing, though present, was less pronounced than in other species. There was a prominent polymorphonuclear response, and extravasation of fibrin and red cells occurred. Primary demyelination was a transient, early feature of the disease process in mice, but nerve fiber depletion and gliosis occurred as the disease progressed. The observed myelin degradation most commonly involved the ingestion by macrophages of small fragments of dissociated myelin via crypts or infoldings of the cell surface, at the bases of which were pinocytic, coated vesicles. A similar pattern of myelin breakdown has been described in mouse hepatitis virus encephalomyelitis and multiple sclerosis.

Animals↗
PubMed1974

Cerebral reticulum cell sarcoma after multiple renal transplants.

A case is reported of a 34 year old white male with chronic renal failure secondary to glomerulonephritis who received four renal transplants over a period of five years. He died 25 months after the fourth transplant. Necropsy revealed a reticulum cell sarcoma-microglioma of the brain. The possibility that multiple transplants may have had a synergistic effect in the development of a malignant cerebral lymphoma in this patient is briefly discussed in the light of the current theories concerning the pathogenesis of the tumours in transplant recipients and in the context of the present therapeutic approach to graft rejection.

Adult↗