γ-Glutamyl Cyclotransferase: A New Genetic Polymorphism in the Mouse (MUS MUSCULUS) Linked to LYT–2

Electrophoretically variant forms of gamma-glutamyl cyclotransferase have been identified in red cells of inbred mouse strains. Each inbred strain exhibited a major band of activity and a minor band that migrated more anodally. The polymorphism affects the migration of both the major and minor bands in a similar way. F1 hybrids between strains with fast forms (A/J) and strains with the slow forms (C57BL/6J) exhibited a four-banded pattern consistent with co-dominant inheritance. The patterns observed in backcross and F2 mice were consistent with the segregation of a pair of autosomal co-dominant alleles. Recombinant inbred strains and a congenic strain were used to show that the locus controlling gamma-glutamyl cyclotransferase (Ggc) is linked to Lyt-2, a lymphocyte alloantigen locus on chromosome 6, with an estimated map distance of 5.0 +/- 2.5 centimorgans.     

The Effects of Mutations in the Ant Promoter of Phage P22 Depend on Context

Restriction fragment length polymorphisms have been identified between inbred strains of mice for the homeo box gene complex Hox-2. These genetic markers were used to follow the segregation of different Hox-2 alleles among recombinant inbred strains of mice and among the progeny of a three point genetic cross. The results place the Hoax-2 locus approximately 1 cM from the rex (Re) locus on mouse chromosome 11.     

Analysis of the mouseAmy locus in recombinant inbred mouse strains

Pancreatic and salivary amylase cDNA probes have been used to search for new DNA fragment length variation among a total of 43 inbred mouse strains. Fragment length differences found with three restriction endonucleases grouped the strains into two major classes. The segregation of these variant fragments has been analyzed among several sets of recombinant inbred strains and is presented here. Previously reported differences for strains YBR and CE have been confirmed. New segregation data for carbonic anhydrase, a locus near the proximal end of mouse chromosome 3, are presented.     

Segregation of restriction fragment length polymorphism in an interspecies cross of laboratory and wild mice indicates tight linkage of the murine IFN-beta gene to the murine IFN-alpha genes.

Southern blot analysis with murine (Mu) interferon (IFN)-alpha cDNA of restricted genomic DNA of three inbred strains of mice belonging to the species Mus musculus domesticus (BALB/c, C57BL/6, and DBA/2) revealed only a limited degree of polymorphism. For example, with HindIII there were only two polymorphic bands out of 14 hybridizing fragments. With Mu IFN-beta cDNA there was no polymorphism at all between BALB/c and C57BL/6 in DNA restricted with seven different enzymes. In contrast, HindIII-restricted DNA of an inbred strain of wild mice (M. spretus Lataste) hybridized with the IFN-alpha probe displayed a high degree of polymorphism compared with the three strains of laboratory mice and was also polymorphic when probed with IFN-beta cDNA. Although M. musculus domesticus and M. spretus Lataste represent different species, certain interspecies crosses are possible in the laboratory. This enabled us to follow segregation of restriction fragment length polymorphism in HindIII-restricted DNA obtained from 18 backcross progeny of a (DBA/2 X M. spretus)F1 X DBA/2 interspecies cross. There was complete coincidence between the segregation of parental (DBA/2) and (DBA/2 X M. spretus)F1-type IFN-beta and IFN-alpha restriction fragment length polymorphism, indicating tight linkage of the IFN-beta and IFN-alpha genes. In addition, in 15 of 18 progeny the segregation coincided with that of the brown locus on chromosome 4, in accord with previous results obtained with the IFN-alpha probe in strains derived from crosses between BALB/c and C57BL/6 mice. Thus, the Mu IFN-beta gene is tightly linked to the Mu IFN-alpha gene cluster on chromosome 4 near the brown locus.     

Chromosomal localization of zinc finger protein genes in man and mouse

We have determined the mouse and human chromosomal location of a gene (Zfp-3) that codes for a protein that contains potential DNA zinc-binding fingers. An analysis of the segregation of restriction fragment length polymorphisms in recombinant inbred strains and in an interspecific backcross demonstrated that Zfp-3 is located on mouse chromosome 11. Zfp-3 is very closely linked to the Trp53-1 locus but unlinked to another finger protein gene Zfp-4 located on mouse chromosome 8. In humans ZFP3 has been localized to chromosome 17p12-17pter and thus is part of the conserved linkage group between this chromosome and the distal half of mouse chromosome 11.     

Linkage analysis of the Bcg gene on mouse chromosome 1. Identification of a tightly linked marker

We have mapped and determined the gene order of five cloned genes in the vicinity of the murine host resistance gene Bcg on mouse chromosome 1. For this, we have used a RFLP-type analysis in panels of 43 recombinant inbred strains, 3 congenic mouse strains, and 186 segregating backcross progeny derived from inbred strains of Bcgr and Bcgs genotypes. The Bcg alleles of segregating animals were established by in vivo infection with Mycobacterium bovis (Bacillus Calmette-Guérin) strain Montreal. Genomic DNA prepared from progenitor mouse strains was isolated, digested with restriction endonucleases, and analyzed by Southern blotting to identify strain-specific RFLP for each DNA marker tested. Among a number of DNA markers tested, Len2, Fn, Vil, Alpi, and Achrg were found to co-segregate with Bcg in mouse strains congenic for this locus. Detailed segregation analysis of the five markers and Bcg showed that Vil was extremely close to Bcg with no recombinant identified, whereas Fn and Len2 were located 4.5 and 9 cM proximal of Bcg, respectively. Alpi and Achrg mapped 5 and 5.5 cM distal from Bcg, respectively. Pedigree analysis in the recombinant inbred strains and backcross animals indicated the gene order: centromere-Len2-Fn-Vil,Bcg-Alpi-Achrg. The tightly linked Vil marker can now be used as an entry point in recombinant genomic DNA libraries to clone sequences overlapping Bcg. This group of five genes flanking Bcg on mouse chromosome 1 is precisely conserved on the telomeric end of the long arm of human chromosome 2q. Our results suggest that a likely location for a putative human homologue to the murine host resistance gene Bcg is the long arm of human chromosome 2 (2q32-qter).     

Novel DNA polymorphism in the mouse tumor necrosis factor receptors type 1 and type 2

The introduction of the polymerase chain reaction (PCR) provides an entirely new means of analyzing DNA polymorphism and makes practical the analysis of length variation in simple-sequence tandem repeats of dinucleotides. In the process of cloning and sequencing the mouse genomic DNA for tumor necrosis factor (TNF) receptors type 1 and type 2, we identified two simple dinucleotide repeats within the noncoding regions of TNF receptor type 1 and three such sequences within TNF receptor type 2. PCR analysis of these sequences, using genomic DNA from 21 different inbred and wild mouse strains, as demonstrated by running the amplified products on sequencing gels, showed that the repeats are highly polymorphic. We identified seven alleles of TNF receptor type 2 and five alleles of TNF receptor type 1. Using these polymorphic markers in two sets of recombinant inbred strains of mice, the chromosomal localization of Tnfr-1 was mapped to mouse chromosome 6 and Tnfr-2 was located to the distal portion of mouse chromosome 4.     

Chromosomal mapping of murine c-fes and c-src genes.

The murine homologs of two viral oncogenes associated with tyrosine-specific kinase activity have been assigned to different loci in the mouse genome. The segregation of restriction site polymorphisms, as detected by probes that are specific for endogenous c-fes and c-src sequences, was followed in the DNA of recombinant inbred strains. The c-fes gene was mapped to the proximal portion of chromosome 7, very close to the Gpi-1 locus, whereas c-src was linked to the Psp locus on the distal half of chromosome 2.     

A catalog of nonsynonymous polymorphism on mouse Chromosome 16

Numerous phenotypic traits differ among inbred mice, and the genetic diversity of inbred strains has been exploited in studies of quantitative trait loci (QTL). Sequencing the mouse genome has resulted in improved tools for the study of QTL, but a comprehensive catalog of sequence variants between strains would be of great value in identifying and testing potentially causative alleles. A/J DNA was included in the Celera shotgun sequence of the mouse genome and C57BL/6 DNA was sequenced by an international consortium. We have resequenced A/J and B6 DNA to cover nearly all of the protein-coding portions of mouse Chromosome 16, revealing that there are 106 nonsynonymous substitutions in 74 of the 779 genes on the chromosome. The pattern of substitution is more similar to the spectrum of benign polymorphism in the human population than it is to human disease-causing mutations. In mouse, polymorphic variants tend to be associated with one another on large haplotypes; this pattern also holds true for nonsynonymous polymorphism. However, sufficient fragmentation of haplotypes is present to suggest that only a very-high-resolution haplotype map will enable effective inference of alleles in additional strains. SNP data have been submitted to dbSNP with ssid No. 46531525-46532013.     

Chromosomal location of the gene encoding the murine acute-phase protein serum amyloid P-component (SAP)

A full-length cDNA clone, pmSAP3, encoding the serum P component (SAP), has been used to search for DNA fragment length variation among mouse strains previously analyzed for differences in endogenous SAP levels. Three alleles were found usingEcoRI-digested DNA. The finding of a single 5.4-kb fragment, alleled, in DNA from DBA/2J mice suggests the presence of a singleSap locus. Segregation of DNA fragment associated withSap ^b andSap ^d alleles was analyzed in three sets of recombinant inbred (RI) strains. The strain distribution pattern found for theSap alleles was identical to that of alleles ofLy-9 in 43 individual RI strains, suggesting tight linkage withLy-9 on mouse chromosome 1. In the BXD RI strains, the SDP of theSap locus, defined by the difference in the endogenous SAP level, is also identical to the SDP of the DNA fragments. We propose to redesignate theSap locus to include both the structural element defined by the DNA polymorphism and the regulatory element involved in the regulation of SAP synthesis. TheSap locus is the major genetic element contributing to the regulation of SAP production. Other genetic factors are also involved, as shown by the presence of nonparental phenotypes in the individual BXH RI strains. This study was performed through special Coordination Funds of the Science and Technology Agency of the Japanese Government and PHS Grant GM24464 to R.W.E.     

Localization of the cryptdin locus on mouse chromosome 8

Cryptdin is a defensin-related peptide, and its mRNA accumulates to high abundance in epithelial cells of intestinal crypts beginning in the second week of postnatal development. The cryptdin (Defcr) locus was assigned to mouse chromosome 8 by Southern blotting of DNAs from mouse/hamster somatic hybrid cell lines. Analysis of somatic hybrid DNAs for mouse-specific restriction fragments showed zero discordance and perfect concordance with chromosome 8. The Defcr locus was localized on chromosome 8 by analysis of DNAs from recombinant inbred (RI) strains of mice after identification of three potential Defcr alleles based on restriction fragment length polymorphisms (RFLPs) in inbred strains. The strain distribution patterns of the Defcr locus were compared with those of chromosome 8 markers in five panels of RI strains. Analysis of cosegregation of Defcr with xenotropic proviral locus Xmv-26 and additional loci confirmed the chromosomal assignment and showed that Defcr is on proximal chromosome 8 within approximately 6 (1.3 to 21.3) cM of Xmv-26. The mouse Defcr locus and the human defensin gene(s) located on chromosome 8p23 appear to map to homologous regions.     

Characterization, chromosome assignment, and segregation analysis of endogenous proviral units of mouse mammary tumor virus.

In the course of analyzing sites of proviral integration in tumors induced by mouse mammary tumor virus (MMTV), we have isolated recombinant DNA clones corresponding to the 5' and 3' ends of four endogenous MMTV proviruses present in BALB/c and BR6 mice. This has permitted the structural characterization of each locus by detailed restriction mapping and the preparation of DNA probes specific for the cellular sequences flanking each provirus. These probes have been used to trace the segregation patterns of the proviruses, designated Mtv-8, Mtv-9, Mtv-17, and Mtv-21, in a panel of inbred strains of laboratory mice and to map Mtv-17 and Mtv-21 to mouse chromosomes 4 and 8, respectively. The unambiguous resolution of these four proviruses on Southern blots has greatly facilitated the analysis of other endogenous MMTV proviruses in these inbred mice.     

Localization of the growth hormone gene to the distal half of mouse chromosome 11

A DNA fragment size variant for the growth hormone gene, Gh, has been identified among inbred strains of mice. The inbred strains SM/J and CAST/Ei carry the less frequent allele Ghb and 11 other strains carry the Gha allele. Segregation analysis of data from two crosses involving SM/J and NZB/BINJ and a cross involving BALB/cJ and CAST/Ei confirmed the assignment of Gh to mouse chromosome 11 and placed the locus 2.6 +/- 1.8 map units distal to Erba (avian erythroblastosis oncogene A), a position consistent with the assignment of the Gh locus to the q22-q24 region of chromosome 17 on the human map. Segregation analysis also refined the location of Sparc (secreted acidic cysteine-rich glycoprotein) on mouse chromosome 11 to a position 16.7 +/- 4.2 map units proximal to Evi-2 (ecotropic viral integration site 2).     

Molecular Markers for the agouti Coat Color Locus of the Mouse

The agouti (a) coat color locus of the mouse acts within the microenvironment of the hair follicle to control the relative amount and distribution of yellow and black pigment in the coat hairs. Over 18 different mutations with complex dominance relationships have been described at this locus. The lethal yellow (Ay) mutation is the top dominant of this series and is uniquely associated with an endogenous provirus, Emv-15, in three highly inbred strains. However, we report here that it is unlikely that the provirus itself causes the Ay-associated alteration in coat color, since one strain of mice (YBR-Ay/a) lacks the provirus but still retains a yellow coat color. Using single-copy mouse DNA sequences from the regions flanking Emv-15 we have detected three patterns of restriction fragment length polymorphisms (RFLPs) within this region that can be used as molecular markers for different agouti locus alleles: a wild-type agouti (A) pattern, a pattern which generally cosegregates with the nonagouti (a) mutation, and a pattern which is specific to Emv-15. We have used these RFLPs and a panel of 28 recombinant inbred mouse strains to determine the genetic linkage of these sequences with the agouti locus and have found complete concordance between the two (95% confidence limit of 0.00 to 3.79 centimorgans). We have also physically mapped these sequences by in situ hybridization to band H1 of chromosome 2, thus directly confirming previous assignments of the location of the agouti locus.     

Genetic control of two electrophoretic variants of glucosephosphate isomerase in the mouse (Mus musculus)

The autosomal variation and the genetic control of GPI has been determined by a comparison of electrophoretic patterns of F₁ and backcross progeny of three inbred strains of mice. The locus controlling the production of GPI in the mouse has been designated Gpi-1. Two alleles at this locus have been described and designated Gpi-1 ^a and Gpi-1 ^b, which represent, respectively, the slow and fast electrophoretic forms. Twenty-seven inbred strains of mice have been classified for these two alleles. The absence of close linkage of Gpi-1 to seven other genetic loci has been determined. It has been demonstrated that the polymorphism of Gpi-1 is widely distributed in feral mice. GPI was expressed in vitro and in four types of malignant tumors.Supported by U.S. Public Health Service Grants GM-09966, from General Medical Sciences, and GY 4193.     

Male-offspring-specific, haplotype-dependent, nonrandom cosegregation of alleles at loci on two mouse chromosomes

F(1) backcrosses involving the DDK and C57BL/6 inbred mouse strains show transmission ratio distortion at loci on two different chromosomes, 11 and X. Transmission ratio distortion on chromosome X is restricted to female offspring while that on chromosome 11 is present in offspring of both sexes. In this article we investigate whether the inheritance of alleles at loci on one chromosome is independent of inheritance of alleles on the other. A strong nonrandom association between the inheritance of alleles at loci on both chromosomes is found among male offspring, while independent assortment occurs among female offspring. We also provide evidence that the mechanism by which this phenomenon occurs involves preferential cosegregation of nonparental chromatids of both chromosomes at the second meiotic division, after the ova has been fertilized by a C57BL/6 sperm bearing a Y chromosome. These observations confirm the influence of the sperm in the segregation of chromatids during female meiosis, and indicate that a locus or loci on the Y chromosome are involved in this instance of meiotic drive.     

Mouse DNA ''fingerprints'': analysis of chromosome localization and germ-line stability of hypervariable loci in recombinant inbred strains.

Human minisatellite probes cross-hybridize to mouse DNA and detect multiple variable loci. The resulting DNA "fingerprints" vary substantially between inbred strains but relatively little within an inbred strain. By studying the segregation of variable DNA fragments in BXD recombinant inbred strains of mice, at least 13 hypervariable loci were defined, 8 of which could be regionally assigned to mouse chromosomes. The assigned loci are autosomal, dispersed and not preferentially associated with centromeres or telomeres. One of these minisatellites is complex, with alleles 90 kb or more long and with internal restriction endonuclease cleavage sites which produce a minisatellite "haplotype" of multiple cosegregating fragments. In addition, one locus shows extreme germ-line instability and should provide a useful system for studying more directly the rates and processes of allelic variation of minisatellites.     

The Mos proto-oncogene maps near the centromere on mouse chromosome 4

The Mos proto-oncogene, the cellular homolog of the transforming gene of Moloney murine sarcoma virus, was originally assigned to mouse chromosome 4 using independent panels of mouse/hamster somatic cell hybrids. By in situ hybridization to metaphase chromosomes and standard genetic backcrosses, we have confirmed this assignment and determined that Mos maps near the centromere in a region devoid of other markers. We have also identified a restriction fragment length polymorphism (RFLP) that defines two alleles of the Mos locus in selected inbred strains of laboratory mice. Using the RFLP, we determined the strain distribution pattern for the Mos gene in three sets of recombinant inbred strains and in five strains congenic for histocompatibility antigen genes localized on chromosome 4. These results establish Mos as a useful marker in a poorly characterized region of the mouse genome. In addition, these results will facilitate the genetic analysis of the Mos locus.