Identification and genetic mapping of 151 dispersed members of 16 ribosomal protein multigene families in the mouse

More than 150 individual members of 16 ribosomal protein multigene families were identified as DNA restriction fragments and genetically mapped. The ribosomal protein gene-related sequences are widely dispersed throughout the mouse genome. Map positions were determined by analysis of 144 progeny mice from both an interspecific (C57BL/6J × SPRET/Ei)F₁ × SPRET/Ei and an intersubspecific (C57BL/6J × CAST/Ei)F₁ × C57BL/6J backcross. In addition, 30 members of the multigene families encoding PGK1 ODC, and TPI, including five new loci for ODC and one new locus for TPI, were characterized and mapped. Interspecific backcross linkage data for 29 nonecotropic murine leukemia retroviruses endogenous to C57BL/6J mice are also reported. Transmission ratio distortions and recombination frequencies are compared between the two backcrosses.     

Fine mapping of Ath6, a quantitative trait locus for atherosclerosis in mice

Ath6 is a novel quantitative trait locus associated with differences in susceptibility to atherosclerosis between C57BL/6J (B6) and C57BLKS/J (BKS) inbred mouse strains. Combining data from an intercross and a backcross (1593 meioses) between mice from B6 and BKS strains and from The Jackson Laboratory interspecific backcross panels, (C57BL/6J ×Mus spretus) F₁× C57BL/6J and (C57BL/6J × SPRET/Ei) F₁× SPRET/Ei, we constructed a consensus genetic map and narrowed Ath6 to a 1.07 ± 0.26 cM interval between the anonymous DNA marker D12Pgn4 and the gene Nmyc1. This region is near the proximal end of murine Chromosome (Chr) 12, which is homologous to the human chromosomal region 2p24-p25. Marker order in the Ath6 region was concordant among the two crosses and The Jackson Laboratory interspecific backcross panels. This high resolution map rules out candidate genes encoding apolipoprotein B, syndecan 1, and Adam17. The two Ath6 crosses have a combined potential resolution of 0.06 cM. Received: 12 September 2000 / Accepted: 22 February 2001     

Mapping of mouse intracisternal A-particle proviral markers in an interspecific backcross

We present a linkage map of intracisternal A-particle (IAP) proviral loci. The IAP family consists of 2000 endogenous proviral elements that are widely dispersed in the mouse genome. The map was constructed by using an interspecific backcross and markers defined by oligonucleotide probes specific for subclasses of expressed IAP elements. In genomic DNA from C57BL/6J mouse, these probes each detected from 12 to 44 HindIII restriction fragments that represent junctions between proviral and 5-flanking DNA. The fragments have characteristic strain distribution patterns (SDPs) that are particularly polymorphic in the DNAs of C57BL/6J and Mus spretus mice used for the backcross. IAP loci were placed on the map by comparison of their distribution patterns with those of known genetic markers in the backcross. The map includes 51 IAP loci that have not been previously mapped and 23 IAP proviruses that had been previously mapped in recombinant inbred (RI) strains. Comparable map positions were obtained with the IAP markers in the interspecific backcross and the RI strains. The mapped IAP loci were widely dispersed on the X Chromosome (Chr) and all of the autosomes except Chrs 9 and 19, providing useful genetic markers for linkage studies.     

An interstitial telomere array proximal to the distal telomere of mouse chromosome 13

Lambda clones of mouse DNA from BALB/c and C57BL/10, each containing an array of telomere hexamers, were localized by FISH to a region close to the telomere of Chr 13. Amplification of mouse genomic DNA with primers flanking SSRs within the cloned DNA showed several alleles, which were used to type eight sets of RI strains. The two lambda clones contained allelic versions of the interstitial telomere array, Tel-rs4, which is 495 bp in C57BL/10 and which includes a variety of sequence changes from the consensus telomere hexamer. Comparison of the segregation of the amplification products of the SSRs with the segregation of other loci in an interspecies backcross (C57BL/6JEi × SPRET/Ei) F₁× SPRET/Ei shows recombination suppression, possibly associated with ribosomal DNA sequences present on distal Chr 13 in Mus spretus, when compared with recombination in an interstrain backcross, (C57BL/6J × DBA/J) F₁× C57BL/6J, and with the MIT F₂ intercross. Analysis of recombination in females using a second interstrain backcross, (ICR/Ha × C57BL/6Ha) F₁× C57BL/6Ha, also indicates recombination suppression when compared with recombination in males of the same strains, using backcross C57BL/6Ha × (ICR/Ha × C57BL/6Ha) F₁. Thus, more than one cause may contribute to recombination suppression in this region. The combined order of the loci typed was D13Mit37–D13Mit30–D13Mit148–(D13Rp1, 2, 3, 4, Tel-rs4)–D13Mit53–D13Mit196–D13Mit77–(D13Mit78, 35). Data from crosses where apparently normal frequencies of recombination occur suggest that the telomere array is about 6 map units proximal to the most distal loci on Chr 13. This distance is consistent with evidence from markers identified in two YAC clones obtained from the region. Received: 24 September 1996/Accepted: 20 January 1997     

Response of TNF-hyporesponsive SPRET/Ei mice in models of inflammatory disorders

Most inflammatory disorders are becoming more prevalent, especially in Western countries. The proinflammatory cytokine tumor necrosis factor- (TNF) plays a prominent role in many of these inflammatory disorders. We have previously shown that SPRET/Ei mice exhibit an extreme and dominant resistance to high doses of TNF. In this report, we investigate the response of heterozygous (C57BL/6xSPRET/Ei)F1 mice in different models of inflammatory diseases. Compared with C57BL/6 mice, (B×S)F1 mice are protected against TNF-induced arthritis and are partially protected against allergic asthma in an ovalbumin-induced model. However, these mice display complete susceptibility to TNF-induced inflammatory bowel disease. These results indicate that the SPRET/Ei genome harbors potent dominant antiinflammatory genes that might be relevant for the treatment of certain chronic inflammatory diseases. It is very well possible that different genes are implicated in the different models.     

New murine polymorphisms detected by random amplified polymorphic DNA (RAPD) PCR and mapped by use of recombinant inbred strains

Oligonucleotide primers of random sequence that were 12 bases in length, 58% in GC content, and lacking internal palindromes were designed. By random amplified polymorphic DNA (RAPD) PCR, these primers were used to survey for DNA variations between the progenitors of the mouse AXB and BXA recombinant inbred sets (A/J and C57BL/6J). We identified 17 DNA variants detected by 10 primers. Map positions for these variants were determined by comparing their strain distribution patterns in the AXB, BXA recombinant inbred sets with strain distribution patterns of previously published loci. When necessary, BXD and NXSM recombinant inbred sets were also used. These 17 new loci mapped to 12 chromosomes. The 10 primers were also used to survey 20 inbred mouse strains including the progenitors of other recombinant inbred sets and four mouse strains recently inbred from the wild (CAST/Ei, MOLF/Ei, PERA/Ei, and SPRET/Ei).     

Localization of the murine cholecystokinin A and B receptor genes

We have determined the chromosomal locations of the two cholecystokinin (CCK) receptor genes in the mouse. Genetic localization utilized an interspecific backcross panel formed from the cross (C57BL/6J x Mus spretus) F₁ x Mus spretus. Genomic DNAs from 94 individuals in the backcross were analyzed by Southern hybridization with rat CCK_A and CCK_B receptor cDNA probes. Unique map positions were determined by haplotype analysis with 650 previously mapped loci in the mouse backcross. The CCK_A receptor gene (Cckar) mapped to mouse Chromosome (Chr) 5, in tight linkage with the DNA marker D5Bir8. The CCK_B receptor gene (Cckbr) mapped to mouse Chr 7, tightly linked to the -hemoglobin locus (Hbb). This localization places Cckbr in the same region as the mouse obesity mutation tubby (tub), which also maps near Hbb (2.4±1.4 cM). Since CCK can function as a satiety factor when administered to rodents, localization of Cckbr near the tub mutation identifies this receptor as a possible candidate gene for this obesity mutation.     

The H-mshi antigen is conserved among standard BALB/cBy, C57BL/6J, and wild-derived CAST/Ei and SPRET/Ei inbred strains of mice

 The recessive male sterility and histoincompatibility mutation (mshi) arose spontaneously in the standard inbred mouse strain BALB/cBy. In addition to generating sterility in homozygous males, mshi controls the loss of a minor histocompatibility antigen designated H-mshi. To determine whether the H-mshi antigen normally expressed by the BALB/cBy strain (H-mshi^c) is the same as or different from the antigen (H-mshi^x) expressed by the standard inbred C57BL/6J strain or the wild-derived CAST/Ei and SPRET/Ei strains, animals heterozygous for the mutant antigen-loss allele (H-mshi ^– ) and H-mshi ^x were grafted with tail skin from BALB/cBy mice. The long-term retention of grafts by these hosts indicates that the H-mshi antigen encoded by the BALB/cBy, C57BL/6J, CAST/Ei, and SPRET/Ei strains is histogenically identical. Conservation of this minor histocompatibility antigen among these evolutionarily diverse strains suggests that H-mshi encodes a functionally important cellular product(s). Received: 1 August 1998 / Accepted: 26 October 1998     

Visual detection, pattern discrimination and visual acuity in 14 strains of mice

Based on the procedure of Prusky et al. (2000, Vision Research, 40, 2201-2209), we used a computer-based, two-alternative swim task to evaluate visual detection, pattern discrimination and visual acuity in 14 strains of mice from priority groups A and B of the JAX phenome project (129S1/SvImJ, A/J, AKR/J, BALB/cByJ, BALB/cJ, C3H/HeJ, C57BL/6J, CAST/Ei, DBA/2J, FVB/NJ, MOLF/Ei, SJL/J, SM/J and SPRET/Ei). Each mouse was tested for eight trials/day for 8 days on each of the three tests. There was a significant strain difference in visual ability in all three tests. Mice with reported normal vision (129S1/SvImJ, C57BL/6J and DBA/2J) and one albino strain (AKR/J) performed very well in these tasks. The other albino strains (A/J, BALB/cByJ and BALB/cJ) took longer to learn the tasks than mice with normal vision and did not reach the criterion of 70% correct. Mice with retinal degeneration (C3H/HeJ, FVB/NJ, MOLF/Ei and SJL/J) performed only at chance levels as did the three strains with unknown visual abilities (CAST/Ei, SM/J and SPRET/Ei). Because many behavioral tasks for rodents rely on visual cues, we suggest that the visual abilities of mice should be evaluated before they are tested in commonly used visuo-spatial learning and memory tasks.     

Macronutrient diet selection in thirteen mouse strains

The strain distribution for macronutrient diet selection was described in 13 mouse strains (AKR/J, NZB/B1NJ, C57BL/6J, C57BL/6ByJ, DBA/2J, SPRET/Ei, CD-1, SJL/J, SWR/J, 129/J, BALB/cByJ, CAST/Ei, and A/J) with the use of a self-selection protocol in which separate carbohydrate, fat, and protein diets were simultaneously available for 26-30 days. Relative to carbohydrate, nine strains consumed significantly more calories from the fat diet; two strains consumed more calories from carbohydrate than from fat (BALB/cByJ, CAST/Ei). Diet selection by SWR/J mice was variable over time, resulting in a lack of preference. One strain (A/J) failed to adapt to the diet paradigm due to inadequate protein intake. Comparisons of proportional fat intake across strains revealed that fat selection/consumption ranged from 26 to 83% of total energy. AKR/J, NZB/B1NJ, and C67BL/6J mice self-selected the highest proportion of dietary fat, whereas the CAST/Ei and BALB/cByJ strains chose the lowest. Finally, epididymal fat depot weight was correlated with fat consumption. There were significant positive correlations in AKR/J and C57BL/6J mice, which are highly sensitive to dietary obesity. However, absolute fat intake was inversely correlated with epididymal fat in two of the lean strains: SWR/J and CAST/Ei. We hypothesize that the SWR/J and CAST/Ei strains are highly sensitive to a negative feedback signal generated by increasing body fat, but the AKR/J and C67BL/6J mice are not. The variation in dietary fat selection across inbred strains provides a tool for dissecting the complex genetics of this trait.     

Localization of insulin-2 (Ins-2) and the obesity mutant tubby (tub) to distinct regions of mouse chromosome 7.

A DNA mapping panel derived from an interspecific backcross was used to position the mouse insulin-2 locus (Ins-2) on Chromosome 7, near H19 (0/114 recombinants) and Th (1/114 recombinants). Ins-2 is part of a human-mouse conserved linkage group that includes Th, H19, and Igf-2. Analysis of segregation in the F2 generation from the cross C57BL/6J-tub/tub x CAST/Ei demonstrated that Ins-2 and the obesity mutant tubby (tub) are distinct loci, thus eliminating Ins-2 as a candidate gene for tub. These results also refine the estimated genetic distance between tub and Hbb to 2.4 +/- 1.4 cM. The predicted location for a human homolog of tubby is HSA 11p15.     

Teratocarcinoma transplantation rejection loci: AnH-2-linked tumor rejection locus

Embryoid bodies (ascites tumor) from a 129/Sv transplantable teratocarcinoma produce tumors (100%) in syngenic 129/Sv mice but fail to form tumors (3–6%) in BALB/c mice, C3H/He mice and C57BL/6 mice, in spite of the fact that the malignant stem cells of this tumor do not express detectable H-2 antigens. The available evidence indicates that this allogeneic tumor restriction has an immunological basis; 100% of the F₁ hybrid mice between 129/Sv and the three other inbred mouse strains accept the 129/Sv teratocarcinoma. The backcross and F₂ mice segregate the BALB/c, C3H/He and C57BL/6 tumor transplantation rejection loci in a manner that indicates that each of these inbred strains of mice contain one to two major transplantation rejection loci. A linkage analysis in the BALB/c and C3H/He backcross and F₂ generations indicates that these mice have a teratocarcinoma transplantation rejection locus on chromosome 17, about eight to nine recombination units from theH- 2 complex. An F₁ complementation analysis between allogeneic mice that each reject teratocarcinomas tumors (BALB/c × C57BL/6 and C3H/He × C57BL/6), indicates that the C57BL/6 mice have the 129/Sv tumor-accepting (sensitive) allele at theH-2-linked locus but reject teratocarcinomas because of antigenic differences at a second locus.While these major teratocarcinoma transplantation rejection loci determine the acceptance or rejection of a tumor by a mouse injected with high doses of tumor tissue (750 g of tumor protein), evidence is presented for a number of minor genetic factors that can (1) affect the efficiency of tumor rejection and (2) cause complete tumor rejection at lower tumor doses (7.5–75 g of tumor protein).     

Reciprocal Hemizygosity Analysis of Mouse Hepatic Lipase Reveals Influence on Obesity

Objectives: We previously demonstrated coincident quantitative trait loci (QTLs) for percentage body fat, plasma hepatic lipase (HL) activity, and plasma cholesterol on mouse chromosome 7. In the present study, we investigated whether hepatic lipase (Lipc) is an obesity gene, whether Lipc interacts with an unknown gene on chromosome 7, and how HL activity is linked to the chromosome 7 locus. Research Methods and Procedures: BSB mice are a model of complex obesity due to interactions among genes from C57BL/6J and Mus spretus (SPRET) in (C57BL/6J × SPRET) × C57BL/6J backcross mice. Five crosses tested the impact on obesity of combinations of inactive (knockout) and wild‐type Lipc alleles from C57BL/6J or SPRET in a reciprocal hemizygosity analysis. Results: The combined data from this allelic series suggest that Lipc alleles, and not alleles from a gene linked to Lipc, influence obesity. No interaction between Lipc and chromosome 7 was demonstrated. We confirmed the chromosome 7 QTLs for obesity, HL activity, and cholesterol. Because obesity and HL activity are not consistently associated in the BSB model, linkage of HL activity to chromosome 7 is not secondary to obesity per se. We also report, for the first time to our knowledge, a QTL in mammals for food intake. Discussion: This use of reciprocal hemizygosity analysis in mammals, which, to our knowledge, is the first reported, reveals its power to detect previously unknown effects of Lipc on obesity.     

Mapping anti-müllerian hormone (Amh) and related sequences in the mouse: identification of a new region of homology between MMU10 and HSA19p.

A panel of 78 backcross progeny, BALB/cJ x (BALB/cJ x CAST/Ei)F1, was used to map the gene encoding anti-Müllerian hormone (Amh), also called Müllerian inhibiting substance, to mouse Chromosome 10 (MMU10). This analysis identified a new region of linkage homology between human Chromosome 19p (HSA 19p) and MMU10 and localized an apparent recombinational hot spot in (C57BL/6J x Mus spretus)F1 females [compared with (BALB/cJ x CAST/Ei)F1 males] to the interval between phenylalanine hydroxylase (Pah) and mast cell growth factor (Mgf). In addition, eight unlinked polymorphic sequences, provisionally designated Amh-related sequences (Amh-rs1 through Amh-rs8), were identified by Southern blot analysis using Amh probes. Amh-rs1, -rs2, -rs4, and -rs7 were mapped to MMU1, 13, 12, and 15, respectively, by recombinant inbred (RI) strain and intraspecific backcross analyses. The NXSM RI strain distribution patterns for the four unmapped loci are also presented.     

A High-Resolution Map in the Chromosomal Region Surrounding theLpsLocus

TheLpslocus on mouse chromosome 4 controls host responsiveness to lipopolysaccharide, a major component of the outer membrane of Gram-negative bacteria. The C3H/HeJ inbred mouse strain is characterized by a mutantLpsallele (Lps^d) that renders it hyporesponsive to LPS and naturally tolerant of its lethal effects. To identify theLpsgene by a positional cloning strategy, we have generated a high-resolution linkage map of the chromosomal region surrounding this locus. We have analyzed a total of 1604 backcross mice from a preexisting interspecific backcross panel of 259 (Mus spretus× C57BL/6J)F1 × C57BL/6J and two novel panels of 597 (DBA/2J × C3H/HeJ)F1 × C3H/HeJ and 748 (C57BL/6J × C3H/HeJ)F1 × C3H/HeJ segregating atLps.A total of 50 DNA markers have been mapped in a 11.8-cM span overlapping theLpslocus. This positions theLpslocus within a 1.1-cM interval, flanked proximally by a large cluster of markers, including three known genes (Cd30l, Hxb,andAmbp), and distally by two microsatellite markers (D4Mit7/D4Mit178). The localization of theLpslocus is several centimorgans proximal to that previously assigned.     

Pleiotropic and other genetic effects influencing the activities of brain and liver enzymes in congenic lines of C57BL/6J mice with defined electrophoretic variant markers

A single genetic factor may affect the realization of several enzymes. To investigate the extent of pattern pleiotropy in the mouse, the activities of 28 enzymes in livers and brains from an inbred stock of C57BL/6J Nctr and five F₁ stocks heterozygous for known electrophoretic variants were measured. Five congenic backcross stocks of C57BL/6J, each homozygous for one or more electrophoretic markers, were mated with C57BL/6J Nctr to construct the heterozygous variant F₁ stocks. One of the five F₁ stocks had no enzyme activities significantly different from those of C57BL/6J Nctr, while two had one enzyme, one had four enzymes, and another had six enzymes with activities that were significantly different from those of C57BL/6J Nctr. The latter two F₁ stocks with multiple activity differences were those having the largest proportion of their genome of donor origin. Two of the F₁ stocks were different from each other for one enzyme, and two were different for another enzyme. These differences and the relationship of these enzyme activities to the variant genes suggest that several genetic factors may affect an enzyme's realization.     

Genome-wide screening for genetic loci associated with noise-induced hearing loss

Noise-induced hearing loss (NIHL) is one of the more common sources of environmentally induced hearing loss in adults. In a mouse model, Castaneous (CAST/Ei) is an inbred strain that is resistant to NIHL, while the C57BL/6J strain is susceptible. We have used the genome-tagged mice (GTM) library of congenic strains, carrying defined segments of the CAST/Ei genome introgressed onto the C57BL/6J background, to search for loci modifying the noise-induced damage seen in the C57BL/6J strain. NIHL was induced by exposing 6-8-week old mice to 108 dB SPL intensity noise. We tested the hearing of each mouse strain up to 23 days after noise exposure using auditory brainstem response (ABR). This study identifies a number of genetic loci that modify the initial response to damaging noise, as well as long-term recovery. The data suggest that multiple alleles within the CAST/Ei genome modify the pathogenesis of NIHL and that screening congenic libraries for loci that underlie traits of interest can be easily carried out in a high-throughput fashion.