Biomedical subjects
Publications and source records attributed to J T Eppig.
The Mammalian Comparative Database provides genetic maps of mammalian species. Comparative maps are valuable aids for predicting linkages, developing animal models and studying genome organization and evolution.
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We describe a service that permits users to draw a genetic linkage map by email. The map that is produced displays loci at their relative positions along a chromosome and can be varied in a number of ways to suit individual needs. The user sends a text file via email and receives by return email a postscript file. This file, when sent to a postscript printer, will produce a genetic linkage map.
We established two mouse interspecific backcross DNA panels, one containing 94 N2 animals from the cross (C57BL/6J x Mus spretus)F1 x C57BL/6J, and another from 94 N2 animals from the reciprocal backcross (C57BL/6J x SPRET/Ei)F1 x SPRET/Ei. We prepared large quantities of DNA from most tissues of each animal to create a community resource of interspecific backcross DNA for use by laboratories interested in mapping loci in the mouse. Initial characterization of the genetic maps of both panels has been completed. We used MIT SSLP markers, proviral loci, and several other sequence-defined genes to anchor our maps to other published maps. The BSB panel map (from the backcross to C57BL/6J) contains 215 loci and is anchored by 45 SSLP and 32 gene sequence loci. The BSS panel map (from the backcross to SPRET/Ei) contains 451 loci and is anchored by 49 SSLP loci, 43 proviral loci, and 60 gene sequence loci. To obtain a high density of markers, we used motif-primed PCR to "fingerprint" the panel DNAs. We constructed two maps, each representing one of the two panels. All new loci can be located with a high degree of certainty on the maps at current marker density. Segregation patterns in these data reveal several examples of transmission ratio distortion and permit analysis of the distribution of crossovers on individual chromosomes.
Technological advances have made possible the development of high-resolution genetic linkage maps for the mouse. These maps in turn offer exciting prospects for understanding mammalian genome evolution through comparative mapping, for developing mouse models of human disease, and for identifying the function of all genes in the organism.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Cytological analysis of the mouse Y* chromosome revealed a complex rearrangement involving acquisition of a functional centromere and centromeric heterochromatin and attachment of this chromosomal segment to the distal end of a normal Y* chromosome. This rearrangement positioned the Y* short-arm region at the distal end of the Y* chromosome and the pseudoautosomal region interstitially, just distal to the newly acquired centromere. In addition, the majority of the pseudoautosomal region was inverted. Recombination between the X and the Y* chromosomes generates two new sex chromosomes: (1) a large chromosome comprised of the X chromosome attached at its distal end to all of the Y* chromosome but missing the centromeric region (XY*) and (2) a small chromosome containing the centromeric portion of the Y* chromosome attached to G-band-negative material from the X chromosome (YX). Mice that inherit the XY* chromosome develop as sterile males, whereas mice that inherit the Y*X chromosome develop as fertile females. Recovery of equal numbers of recombinant and nonrecombinant offspring from XY* males supports the hypothesis that recombination between the mammalian X and Y chromosomes is necessary for primary spermatocytes to successfully complete spermatogenesis and form functional sperm.
The efficacy and outcome of bone marrow transplantation therapy following lethal irradiation were examined in syngeneic mice that had a hereditary macrocytic anemia (an/an) or were genotypically normal (+/+). Successful RBC and WBC replacement, based on blood cell parameters and donor genetic markers, were observed in all combinations of transplant therapy. Nevertheless, the an/an mice died prematurely several months after treatment, whether they received +/+ or an/an marrow cells. In contrast, the +/+ recipients of either +/+ or an/an marrow cells survived for at least 1 year after transplantation. Premature death of the an/an mice was associated with lymphopenia, anemia, kidney lesions, and severe pathogen-free pneumonitis. On the basis of our results, we hypothesize that the premature deaths of an/an mice are caused by a kind of chronic irradiation damage to which an/an mice are especially susceptible.
Mice with the recessive hereditary disease, Hertwig's anemia (an/an), exhibit a persistent mild macrocytic anemia and reduced fertility. We examined mitotic figures from bone marrow and kidney cells of adult mice and from liver cells of fetal mice that were genetically normal or had Hertwig's anemia. Uniformly normal mitotic figures were observed in the nonanemic mice (+/+ or +/an). In contrast, 5% to 15% of the mitotic figures were abnormal in mice homozyous for Hertwig's anemia (an/an). These aberrant cells were hyperploid, containing more than the normal complement of c40 chromosomes, but fewer than 80 chromosomes. Cells with abnormal numbers of chromosomes may show decreased viability or proliferative capacity. The occurrence of such abnormal cells in an/an mice could explain (1) the loss of progenitor stem cells during erythroid maturation, resulting in an anemic phenotype; and (2) the depletion of germ cells during ontogeny, resulting in reduced fertility.