Search

A rat cDNA clone encoding a portion of phosphate-activated glutaminase was used to identify DNA restriction fragment length polymorphisms (RFLPs) in sets of somatic cell hybrids and between wild-derived and inbred strains of mice. Segregation of rat and mouse chromosomes among somatic cell hybrids indicated assignment to rat chromosome 9 and mouse chromosome 1. Analysis of chromosome 1 alleles for several genes in an interspecific cross between Mus spretus and C3H/HeJ-gld/gld mice indicates that glutaminase can be positioned within 5.5 +/- 2.0 cM proximal to Ctla-4. Similarly, human-hamster somatic cell hybrids were examined for RFLPs, and four human EcoRI restriction fragments were found to hybridize with the rat glutaminase probe. Two of these restriction fragments cosegregated and mapped to human chromosome 2 in a region that is syntenic with mouse chromosome 1 and rat chromosome 9.

Allelic variants of Ly-5 in inbred commensal and other natural populations of mice were analyzed by patterns of restriction fragment length polymorphisms (RFLP) and Southern hybridization using an Ly-5 cDNA probe and by cell-surface staining with a panel of antibodies directed against polymorphic and nonpolymorphic Ly-5 determinants. New Ly-5 alleles were defined by RFLPs generated by both Eco RI and Bam HI restriction enzyme digests. The Mus musculus subspecies and other species within the genus Mus showed a strong correlation between allelic variants defined by restriction enzymes and serologic specificities. The data also suggest the conservation of the Ly-5 gene throughout the genus Mus.

We have examined the context of mouse T-cell receptor gamma (Tcr gamma) chain variable (V gamma) and constant (C gamma) genes among a panel of geographically isolated species of mice. Our Southern hybridization survey with C gamma reveals that essentially three C gamma genes are found among mouse species extending phylogenetically from inbred mice through the feral species Mus pahari. However, a V gamma DNA probe detects three to nine V gamma restriction fragment bands among the same group of mice. These results suggest that certain feral mice such as M. pahari, M. platythrix, and M. shortridgei have amplified numbers of V gamma genes. Studies of individual mice from these particular species indicate the highly amplified V gamma content is not the result of a catastrophic gene duplication or deletion event. We conclude that certain species of mice maintain increased content of V gamma presumably for increased diversity in a T-cell response.

DNA from a panel of inbred strains of mice and colony bred mice, isolated from different geographical locations, was hybridized to mouse V preB and lambda 5 probes under stringent conditions, indicating sequence similarities greater than 80%. The probe for lambda 5 detects one gene and the probe for V preB detects two genes (V preB1 and V preB2) in the inbred strains of mice examined under the stringency used. No restriction endonuclease fragment length polymorphisms (RFLP) were detected with the V preB and lambda 5 DNA probes among the inbred strains of mice using Bam HI and Hind III. Very few RFLP were detected among Mus musculus subspecies, and the intensity of the hybridization did not differ significantly with either DNA probe. The number of RFLP increased slightly when different species and subgenera were examined, and the intensity of the hybridization signal began to decrease in samples from the different subgenera, suggesting a slight decrease in sequence similarity for both V preB genes with increased time of divergence. Fewer RFLP were detected with the lambda 5 DNA probe. DNA from 11 different Mus species representing 4 subgenera, genetically isolated from laboratory mice for approximately 1-12 million years, continued to hybridize under high stringency conditions using both DNA probes. A comigrating lambda 5 and V preB restriction endonuclease fragment was detected in most of the samples examined, suggesting the close physical linkage of V preB1 and lambda 5 is maintained within the genus Mus. These results suggest that V preB1, V preB2 and lambda 5 have been present for over 12 million years.

Mo-10, a homeo box-containing sequence in the Hox-1 complex of genes referred to as Hox-1.5, was found to be polymorphic in inbred and wild mice, and a strain distribution of three allelic forms of Hox-1.5 are reported. The position of Hox-1.5 was mapped in backcross experiments to within 1 cM of the hypodactyly locus on chromosome 6. This identifies the Hd mutation as a useful model for the examination of homeo box expression during mammalian development.

The composition of 15 VT beta gene subfamilies has been examined by Southern hybridization among a broad spectrum of colony bred rat and mouse species extending phylogenetically from Rattus to Mus musculus domesticus. Most mouse species contain a similar content of VT beta genes as determined by the number of hybridizing restriction fragment (RF) bands. Furthermore, the extent of restriction fragment length polymorphism (RFLP) appears to be limited. Some VT beta gene families, however, are missing from Rattus (VT beta 7, VT beta 12) and M. shortridgei (VT beta 9, VT beta 16). Extension of the VT beta survey to a panel of 38 wild caught mice reveals that nearly a third lack specific hybridization to the VT beta 5 probe. Previous reports have established that the mouse inbred strains SJL, C57BR, C57L, and SWR lack 50% of their VT beta repertoire, including VT beta 5 (Behlke et al. 1985). This study demonstrates that natural populations of mice also carry a significantly reduced VT beta gene repertoire.

In the mouse three lymphocyte gene families have been positioned on the proximal region of chromosome 6. Originally the immunoglobulin kappa light chain (Igk) and the thymocyte surface antigens Lyt-2 and Lyt-3 were assigned to chromosome 6, and recently the beta chain of the T-cell receptor for antigen was positioned proximal to Igk. Molecular clones which recognize the constant (C) region of the beta chain of the T-cell receptor for antigen (CT beta) and the constant region of the immunoglobulin kappa (C kappa) chain were used to determine recombination frequencies with respect to the morphological marker hypodactyly (Hd). SJL/JL W pi mice were mated with C.B6.C3-Hd/+ mice, and the progeny expressing the Hd phenotype were mated with SJL/JL W pi mice. Backcross progeny which expressed the Hd phenotype were nephrectomized, and kidney DNA was examined by Southern hybridization for the polymorphic restriction endonuclease fragment (REF) patterns of the parental mice. Of the 88 progeny tested in this three-point cross, 3 CT beta and 4 C kappa homozygote REF patterns were detected. These homozygotes were mutually exclusive. This implies the following gene order: centromere-CT beta-Hd-Igk and CT beta 1 would be 7.95 +/- 2.88 centimorgans from C kappa.

Substrains of NZB mice have been compared by Southern blot analysis using several probes. The restriction fragment length polymorphism of probes derived from the Igh-V, Igk-V, Tcr alpha-C loci and of the long terminal repeat of the mouse mammary tumour virus revealed that NZB/BlLwPtIbm were grossly different from NZB/BlNJ and NZB/BlOla. Comparison with mouse strains of the Igk-V haplotypes a and d suggested that NZB/BlLwPtIbm contain genetic material of the C58 mouse strain.

One mouse with a known recombination (NAK) at the Igk locus on chromosome 6 and two new recombinants [B6.PL (75NS) and B6.PL (85NS)] were examined using a series of probes, each of which is specific for a set of immunoglobulin (Ig) Vk genes. Under high stringency conditions, each probe detects from 1 to 19 Bam HI restriction endonuclease fragments (REFs) in genomic DNA by Southern transfer hybridization techniques. Analysis of the REF patterns indicate that the NAK recombination event occurred within the variable region of Igk. The REF patterns of the two B6.PL congenic mice provided two additional recombination events which could be examined. Although some of the REFs had shared mobility among the parental strains, at least 1 and up to 13 polymorphic REFs were present for a given probe among the NZB and AKR parental strains. The results from the NAK mouse indicate that at least some members of Vk4, Vk8, Vk10, and Vk21 were on one side of the recombination event linked to the Lyt-2 alpha and Igk-Ef1 alpha alleles of AKR, while the Vk9, Vk11, and Vk24 REF patterns came from the NZB parental strain linked to the Igk-Ef2 beta (Vk1) allele. The two B6.PL congenics produced a refined map on the Lyt-2, Lyt-3 side of the Vk region. The B6.PL (85NS) mice retained the Vk21 REF pattern of the Lyt-2 alpha, Lyt-3 alpha donor strain PL/J, while displaying the C57BL/6 REF pattern for the other Vk gene groups tested. The B6.PL (75NS) mice retained the REF patterns of PL/J for Vk21 and Ef-1, indicating a third recombination. This indicates the Vk gene order is (Lyt-2; Vk21); Ef-1; (Vk4; Vk8; Vk10); and (Vk9; Vk11; Vk24; Ef-2).