Y Chromosome Evolution in the Subgenus Mus (Genus Mus)

A 305 base pair DNA sequence isolated from the Y chromosome of the inbred mouse strain C57BL/10 was used to investigate the pattern and tempo of evolution of Y chromosome DNA sequences for five species in the subgenus Mus, including Mus spretus, Mus hortulanus, Mus abbotti, Mus musculus and Mus domesticus. Variation in hybridization patterns between species was characterized by differences in fragment lengths of both intensely and faintly hybridizing fragments, whereas variation in hybridization patterns within species was characterized primarily by differences in fragment lengths of faintly hybridizing fragments. Phylogenetic analyses were conducted based on fragment size variation within and among species. Phylogenetic relationships inferred from these analyses partly agree with the phylogenetic relationships obtained from biochemical and mitochondrial DNA data. We conclude that a set of DNA sequences common to the Y chromosomes of a closely related group of species in the subgenus Mus has evolved rapidly as reflected by sequence divergence and sequence amplification.     

Autosomal genes involved in mammalian primary sex determination

Beginning with findings made during the late 1950s and early 1960s, evidence continues to accumulate in support of the hypothesis that the mammalian Y chromosome carries a gene that induces the undifferentiated foetal gonad in XY individuals to develop as a testis. Recently a DNA sequence has been isolated from the human Y chromosome that appears to be the hypothesized Y-linked testis-determining gene, and advances have also been made toward identifying genes that interact with the Y-linked testis-determining (Tdy) gene to initiate testis formation. These loci have been identified in specific stocks of mice carrying the mutant Thp or TOrl allele at the T locus located on chromosome 17, and in crosses involving the transfer of a Y chromosome from two populations of Mus domesticus into the genomes of specific inbred strains of mice. The data in both cases support the hypothesis that there are several loci involved in testis determination and that abnormal interaction of these loci disrupts initiation of testis determination, resulting in development of ovarian tissue in XY individuals.     

Location of phosphorylase kinase (Phk) in the mouse X chromosome

The phosphorylase kinase deficiency (Phk) locus has been located in the mouse X chromosome, the order of genes being centromere-Bn-Phk-Ta-jp. Since the Phk locus of the mouse may be identical to the locus responsible for the X-linked phosphorylase kinase deficiency trait of man, and there may be a high degree of gene-order homology in the X chromosome of all mammals, the location of Phk in the mouse reported here may aid in locating the phosphorylase kinase gene on the X chromosome of man.This research was supported by grants AM 13359 (to F.H.) and AM 14461 (to D.L.C.) from the National Institute of Arthritis and Metabolic Diseases, and by an allocation (to E.M.E.) from NIH General Research Support Grant RR-05545 from the Division of Research Resources to The Jackson Laboratory. F.H. is a recipient of a Research Career Development Award (AM 46 421) of the National Institute of Arthritis and Metabolic Diseases.     

The Original Pink-Eyed Dilution Mutation (P) Arose in Asiatic Mice: Implications for the H4 Minor Histocompatibility Antigen, Myod1 Regulation and the Origin of Inbred Strains

Allelic variation of the mouse pink-eyed dilution (p) gene in common laboratory strains and wild mice was examined by Southern blot and by polymerase chain reaction. In these assays the original p mutation allele found in strains SJL/J, 129/J, B10.129(21m), P/J and FS/Ei most closely matches an Asian Mus musculus allele, confirming anecdotal accounts of the Asian origin of this mutation. In contrast, the wild-type allele found in other common laboratory strains was apparently derived from Mus domesticus. Analysis of chromosome 7 loci both proximal and distal to the p locus demonstrates that strains SJL/J, 129/J, B10.129(21M), P/J and FS/Ei contain DNA segments of varying length derived from M. musculus. Strains 129/J and B10.129(21M) contain the largest segment of M. musculus-derived DNA (about 5 cM), including the loci Myod1, p, three clustered GABA(A) receptor subunit loci (Gabrg3, Gabra5 and Gabrb3), and Snrpn. The difference in the species origin of genes from this region of chromosome 7 may underlie the basis of the antigenicity of the minor histocompatibility antigen H4, defined by the strain B10.129(21M), and may account for the enhanced Myod1 activity observed in SJL/J mice.     

Mapping of nucleoside phosphorylase (Np-1) and esterase 10 (Es-10) on mouse chromosome 14

A method for detecting two alleles at Np-1 (nucleoside phosphorylase) and three alleles at Es-10 (esterase 10) from mouse blood by cellulose acetate electrophoresis is described. The allelic constitution at these loci for 44 inbred strains and stocks was determined. The location of Np-1 on chromosome 14 was established by backcross experiments in which alleles at Np-1 and Robertsonian translocations were segregating. Es-10 was shown to be linked to Np-1, and the following genetic map of Chr 14 was constructed: centromere-(8.9±4.0 cM)-[Np-1, Wc]-(10.2±1.9 cM)-Es-10-(15.5±3.7 cM)-s. The homologous human loci, NP and ES-D, are not linked.This work was supported by Contract E(11-1)-3267 with the Energy Research and Development Administration, by Contracts NO1-ES4-2156 and NO1-ES4-2159 with the National Institute of Environmental Health Sciences, and by Grants GM 19656 and GM 20919 from the National Institute of General Medical Sciences. D. A. K. was a participant in the 1975 Summer Program for College, Graduate, and Medical Students, which was supported, in part, by the Clark Foundation. The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care.     

Antioxidant role and subcellular location of hypotaurine and taurine in human neutrophils.

The subcellular location of taurine, and its precursor, hypotaurine, within human neutrophils has been examined by nitrogen cavitation, Percoll-gradient centrifugation and HPLC analysis. Hypotaurine and taurine were found to reside within the cytosolic compartment of the cell. The ratio of taurine to hypotaurine is approx 50:1. The cytosolic concentration of taurine is approx. 50 mM. The concentration of hypotaurine decreased by 80% when resting neutrophils were converted into actively respiring cells by exposure to opsonized zymosan. These results prompted in vitro studies on the antioxidant properties of hypotaurine. We demonstrate by EPR spectroscopy that hypotaurine competes with 5,5'-dimethyl-1-pyrroline N-oxide) (DMPO) for hydroxyl radicals, and that it is the sulfinyl group which confers hydroxyl radical scavenging activity to it. Following its exposure to hydroxyl radicals, two oxidation products were isolated by HPLC, one of which has been identified as taurine. The biological roles of hypotaurine and taurine in the neutrophil are discussed with respect to their antioxidant properties and subcellular location within the cell.