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C M Warner

Publications and source records attributed to C M Warner.

At least 37 records · Page 2Linked to original sources
PubMed1994

Identification of the Ped gene at the molecular level: the Q9 MHC class I transgene converts the Ped slow to the Ped fast phenotype.

The Ped (preimplantation embryo development) gene, which maps to the Q region of the mouse major histocompatibility complex (MHC), controls the rate of cleavage division of preimplantation mouse embryos and subsequent embryonic survival. Of the ten known MHC class I genes in the Q region of the mouse MHC, four--Q6, Q7, Q8, and Q9--are almost identical and encode similar proteins, all called the Qa-2 antigen. Previous studies have suggested that the Q9 gene encodes the Ped gene. To test this directly, one-cell embryos from the CBA/Ca strain (Ped slow) that is missing the Q9 gene and the Qa-2 antigen were injected with the Q9 gene from the C57BL/10 strain (Ped fast) that possesses the Q9 gene and expresses the Qa-2 antigen. The resulting Q9 transgenic mice were found to express the Qa-2 antigen. In addition, it was found that introduction of the Q9 gene converted the Ped gene phenotype of the recipient strain from slow to fast. Therefore, the Ped gene product is the Qa-2 antigen encoded by the Q9 gene.

Animals↗
PubMed1993

Induction of embryonic major histocompatibility complex antigen expression by gamma-IFN.

Preimplantation mouse embryos were incubated in vitro with mouse recombinant gamma-interferon (IFN). The effect of the gamma-IFN on major histocompatibility complex (MHC) class I antigen expression was tested using an ELISA procedure. It was found that there is a doubling of Db antigens and a tripling of Qa-2 antigens on C57BL/6 mouse embryos cultured from the 8-cell stage for 24 h in the presence of 10(5) units/ml gamma-IFN. The effect of gamma-IFN on the rate of preimplantation embryonic development was tested by culturing 2-cell embryos for 48 h and 8-cell embryos for 24 h in the presence of varying concentrations of gamma-IFN up to 10(6) units/ml. Two methods were used to assess the cell number per embryo after the culture period: incorporation of [3H]thymidine into DNA, and direct counting of nuclei in fixed and stained embryos. Both methods showed that treatment with gamma-IFN increases the rate of development of preimplantation mouse embryos. Since rate of preimplantation embryonic development is genetically controlled by the Ped gene, it is suggested that gamma-IFN has a direct effect on the Ped gene phenotype of preimplantation mouse embryos.

Animals↗
PubMed1993

Modulation of preimplantation embryonic development by antisense oligonucleotides to major histocompatibility complex genes.

The Ped (preimplantation embryo development) gene, which controls the rate of mouse preimplantation embryonic cleavage division and subsequent survival of the embryo, maps to the Q region of the MHC (major histocompatibility complex). Mouse embryos were treated with antisense oligonucleotides to mRNA for the Q region genes Q7/Q9, each of which encodes the Qa-2 antigen. The reverse transcription polymerase chain reaction (RT-PCR) was used to show that antisense treatment, but not sense treatment, decreased the level of mRNA for Qa-2 antigen in preimplantation embryos. Furthermore, both the expression of Qa-2 protein and the rate of embryonic cleavage division were decreased by treatment with antisense but not sense oligonucleotides. These results provide direct evidence that the Ped gene phenotype is at least partially encoded by the Q7/Q9 genes. It is likely that the mouse Ped gene has a human homolog, perhaps within HLA-F. Identification of genes--such as the Ped gene--that affect survival of the embryo may be vitally important for the enhancement of animal and human reproductive success.

Animals↗
PubMed1993

Expression of H-2K major histocompatibility antigens on preimplantation mouse embryos.

Genes in the major histocompatibility complex (MHC) have been shown to play a role in development and reproduction. In the mouse, class I MHC proteins are expressed on oocytes and preimplantation embryos. Each mouse strain contains multiple class I genes located in the classical regions, K and D, and the nonclassical regions, Q and TL, of the mouse MHC, the H-2 complex. This study was undertaken to evaluate the expression of the classical class I MHC antigen, H-2K, on preimplantation mouse embryos. Through use of appropriate monoclonal antibodies (mAb) and an ELISA procedure, it was shown that H-2K antigens are detectable on oocytes and blastocyst-stage embryos, but not on 2-cell or 8-cell embryos. This pattern of expression is different from that reported in previous studies showing expression of total class I antigens and the nonclassical MHC antigen, Qa-2, on all stages of preimplantation embryos, including 2-cell- and 8-cell-stage embryos. To analyze the nature of the H-2K protein on blastocysts, H-2K antigens were isolated from an H-2K overproducing cell line (RDM-4) and used in blocking experiments. It was found that the purified antigen blocked binding to tissue culture cells by 54% and to embryos by 68%. Therefore, H-2K antigens on tissue culture cells and embryos appear to be very similar, but perhaps not identical. Thus escape of embryos from surveillance by the maternal immune system may not be effected by the expression of a different or embryonic form of MHC antigens.

Animals↗
PubMed1993

Isolation and characterization of cDNA clones for chicken major histocompatibility complex class II molecules.

The chicken major histocompatibility complex (MHC), the B complex, is being intensively analysed at the DNA level. To further probe the molecular structure of chicken MHC class II genes, cDNA clones coding for chicken MHC class II (B-L) beta chain molecules were isolated from an inbred G-B2 Leghorn chicken spleen and liver. Twenty-nine cDNA clones were isolated from the spleen and eight cDNA clones were isolated from the liver. Based on restriction maps, most clones could be clustered into one family of genes. Four cDNA clones were sequenced (S7, S10 and S19 from the spleen and L1, which was identical to S19, from the liver). Complete amino acid sequences of B-L beta chain molecules were predicted from the nucleotide sequences of the cDNA clones. Although both the nature and the location of the conserved residues were similar in chicken and mammalian sequences, some species-specific differences were found, suggesting that the structures of the B-L molecules of this haplotype are similar, but not identical, to their mammalian counterparts.

Amino Acid Sequence↗
PubMed1993

Preferential survival of mice expressing the Qa-2 antigen.

The Ped gene, a gene that influences the rate of embryonic cleavage division, birth weight, litter size and weaning weight, is at least partially encoded by gene(s) that specify the Qa-2 antigen. Two congenic strains of mice, B6.K1 (Qa-2 negative) and B6.K2 (Qa-2 positive), which differ only at the Q region of the mouse major histocompatibility complex (MHC), were tested for the effect of the presence or absence of Qa-2 antigen on litter size, duration of gestation and embryo survival. It was confirmed that B6.K1 (Qa-2 negative) mice have smaller litters than do B6.K2 (Qa-2 positive) mice. In addition, the duration of gestation for the B6.K1 mice was found to be longer than the duration of gestation for the B6.K2 mice. Finally, a comparison of the relative survival of Qa-2-positive and Qa-2-negative mice in a single uterine environment showed the preferential survival of mice expressing the Qa-2 antigen. Thus, the presence of Qa-2 antigen appears to be advantageous for reproductive success.

Animals↗
PubMed1993

Lymphocyte aging in bone marrow chimeras.

Chimeric mice provide a unique approach to the analysis of genetic factors associated with aging since cells with two genetically distinct backgrounds can be analyzed in the same animal. In this study, bone marrow chimeras were produced by reconstituting lethally irradiated female B6AF1 [(C57BL/6 female x A male)F1] mice with varying mixtures of T cell-depleted bone marrow cells from A (short-lived) and C57BL/6 (long-lived) mice. The phenotypic composition of the peripheral blood lymphocytes was analyzed using either a cytotoxicity assay or flow cytometry with indirect immunofluorescence. The percentage of A-derived lymphocytes in the peripheral blood following reconstitution was generally higher than the percentage of A bone marrow cells with which the irradiated mice were inoculated, suggesting that the cells from the A donor bone marrow were more efficient at marrow reconstitution than the cells from the C57BL/6 donor bone marrow. In order to determine whether the percentage of A- versus C57BL/6-derived cells changed with age in each animal, the chimeric mice were bled for phenotype analysis of peripheral blood lymphocytes between 2-6 months following reconstitution and at 2-3 month intervals until death. For most animals [93/127 (73%)], there was no consistent pattern of increase or decrease (> 20%) with regard to the percentage of A lymphocytes in the peripheral blood over time. However, in 34/127 (27%) of the chimeras, a change greater than 20% in the phenotypic composition of the peripheral blood lymphocytes was observed and these animals were considered unstable. Among these 34 unstable animals, 6 (18%) showed an overall increase in A-derived lymphocytes, 24 (71%) showed an overall decrease in A-derived lymphocytes, and 4 (12%) showed fluctuating increases and decreases over their lifespan. While the lifespans of the chimeric animals in these studies were considerably shorter than those reported for untreated mice of the same strain and gender, in these animals increased proportions of A cells were associated with significantly longer lifespans. In addition, the lifespan of the B6AF1 chimeric mice was a function of the proportion of A lymphocytes present in the peripheral blood over the course of the animal's life.

Animals↗
PubMed1992

Mapping of the SLA complex of miniature swine: mapping of the SLA gene complex by pulsed field gel electrophoresis.

The overall order of the regions of the swine major histocompatibility complex (MHC), the SLA complex, was determined by pulsed field gel electrophoresis (PFGE). It was found that the order of the regions is class II-class III-class I. A class I probe hybridized to a 420 kb Mlu I and a 420 kb Not I fragment as did a class III probe for C2. None of the class II probes hybridized to these fragments. Thus, linkage of class I to class III was shown. The class III C2, Bf, and C4 genes were found to residue in a 190 kb Not I fragment. Linkage of class III and class II genes was shown when both the class III C4 and the class II DR probes hybridized to the same 195 kb Sac II and 340 kb Not I fragments. The class I probe did not hybridize to these fragments. The order of the regions, class II-class III-class I, is similar to that of human MHC genes and may have been conserved in evolution so that coordinated expression of MHC genes could be achieved.

Animals↗
PubMed1992

Removal of Qa-2 antigen alters the Ped gene phenotype of preimplantation mouse embryos.

Embryo survival is influenced by both genetic and environmental factors. Previous research in our laboratory has identified one gene associated with embryonic survival, the Ped gene, a gene that is linked to the major histocompatibility complex (MHC) of the mouse. The Ped gene has been shown to influence the rate of preimplantation embryonic cleavage division, as well as litter size, birth weight, and weaning weight. Genetic mapping of the Ped gene has located it in the Q region of the MHC and has suggested that possible Q region genes encoding the Ped gene are Q3, Q5, Q6, Q7, Q8, and/or Q9. Whereas the protein products of the Q3 and Q5 genes are unknown, the protein product of the very similar Q6, Q7, Q8, and Q9 genes is the Qa-2 antigen. Two forms of membrane-bound Qa-2 antigen are known: glycosylphosphatidylinositol (GPI)-linked and transmembrane bound. Only the GPI-linked form is sensitive to cleavage by phosphatidylinositol phospholipase C (PI-PLC). The first purpose of the present study was to determine the nature of the linkage of the Qa-2 antigen to the cell surface of preimplantation mouse embryos. It was found that all detectable Qa-2 antigen on the embryonic cell surface is sensitive to cleavage by PI-PLC and is therefore bound to the cell membrane by a GPI linkage. Furthermore, removal of Qa-2 antigen from the embryonic cell surface slows down the rate of development of preimplantation mouse embryos. These results suggest the likelihood that the Qa-2 antigen is the Ped gene product.

Animals↗
PubMed1992

Expression of phosphatidylinositol-dependent phospholipase C sensitive Qa-2 antigen is increased on peripheral blood lymphocytes of aging mice.

Qa-2 antigen, a nonclassical MHC antigen, is one of a group of cell surface antigens that may be anchored to the cell surface by a glycophosphatidylinositol (GPI) linkage rather than, as is the case with the classical MHC antigens, K, D, and L, by a transmembrane linkage. Recent studies have shown that T cells may be activated through the cross-linking of GPI anchored Qa-2 antigens by anti-Qa-2 antiserum. The Qa-2 antigens involved in signal transduction in activated T cells are sensitive to lipolytic cleavage by phosphatidylinositol-dependent-phospholipase C (PI-PLC). Since T cell function is known to decline with age, a study was undertaken to determine whether the relative amount of lipase sensitive Qa-2 antigen changes with age. Ficoll- Hypaque purified peripheral blood lymphocytes were obtained from C57BL/6 and A strain mice from 6-30 months of age. The cells were incubated with or without phosphatidylinositol- dependent-phospholipase C followed by incubation with anti-Qa-2 monoclonal antibodies and a fluorescein labeled second antibody. Analysis on a FACScan flow cytometer demonstrated that the A strain mice had a single population of Qa-2 positive lymphocytes which increased in lipase sensitivity with age. The C57BL/6 strain mice of all ages had two populations of Qa-2 positive cells, one staining with high fluorescence intensity (high antigen density) and the other with low fluorescence intensity (low antigen density). The proportion of cells found in the high density peak increased markedly with age, suggesting on overall increase in Qa-2 expression. In young animals, only the high density peak was sensitive to PI-PLC treatment. In older animals, the cells originally appearing in the high density population shifted to the low density population after treatment with PI-PLC, suggesting that there must be both lipase sensitive and lipase insensitive forms of Qa-2 present on lymphocytes in these aging C57BL/6 mice. Overall, these data suggest that the proportion of lymphocytes expressing lipase sensitive Qa-2 is increased on lymphocytes of old mice. Since a role for lipase sensitive GPI-linked Qa-2-antigen has recently been postulated in T cell activation, it is possible that the increased lipase sensitive Qa-2 antigen may play a role in age-related changes in T cell function.

Aging↗
PubMed1991

Analysis of litter size and weight in mice differing in Ped gene phenotype and the Q region of the H-2 complex.

A gene has been described, Ped (Preimplantation embryo development), that influences the rate of cleavage of preimplantation mouse embryos. Previous studies of linkage of Ped gene phenotype (fast or slow embryo development) and H-2 haplotype (H-2b or H-2k) in backcross embryos from the C57BL/10Sn and B10.BR congenic strains have shown that the Ped gene is located in the H-2 complex, the major histocompatibility complex (MHC) of the mouse. The present study was undertaken to localize the Ped gene to a particular subregion of the H-2 complex. Analysis of the B6.K1 and B6.K2 congenic strains, which differ at only the Q subregion of the MHC, was undertaken to test whether the Ped gene is located in the Q subregion of the MHC. Qa-2 antigen expression was used as a marker for the Q subregion and fast or slow development was used to assess Ped gene phenotype in backcross embryos generated from the mating of (B6.K1 x B6.K2)F1 and B6.K1 mice. The results showed linkage of Ped gene phenotype and Qa-2 antigen expression, which strongly supports the idea that the Ped gene is located in the Q subregion of the MHC. In a further set of experiments, litter size and weight were investigated in the B6.K1 and B6.K2 mice. Pure line and reciprocal crosses were made using sires and dams of both the B6.K1 and B6.K2 genotypes. Traits measured on pups included birth weight, weaning weight and weight per day of age from birth to weaning. Litter traits measured were number born and weaned and survivability. Sex effects existed for weaning weight and weight gain per day of age. Males gained more and were heavier than female pups (P less than 0.05). Pups whose sire or dam were B6.K2 were significantly (P less than 0.05) heavier at birth than those pups whose sire or dam were B6.K1, and B6.K2 homozygous pups were significantly (P less than 0.001) heavier than all others. Litters whose dams were B6.K2 had significantly more pups at birth (P less than 0.05) than those litters whose dams were B6.K1. Results suggest that pups that are heterozygous or homozygous B6.K2 are more apt to be heavier at birth and be in larger litters suggesting that genes in the Q region of the H-2 complex are advantageous to reproductive performance.

Animals↗