The minimal length of the differential segment in H-2 congenic lines

Of volatiles and peptides: in search for MHC-dependent olfactory signals in social communication

Genes of the major histocompatibility complex (MHC), which play a critical role in immune recognition, are considered to influence social behaviors in mice, fish, humans, and other vertebrates via olfactory cues. As studied most extensively in mice, the polymorphism of MHC class I genes is considered to bring about a specific scent signature, which is decoded by the olfactory system resulting in an individual-specific reaction such as mating. On the assumption that this signature resides in volatiles, extensive attempts to identify these MHC-specific components in urine failed. Alternatively, it has been suggested that peptide ligands of MHC class I molecules are released into urine and can elicit an MHC-haplotype-specific behavioral response after uptake into the nose by sniffing. Analysis of the urinary peptide composition of mice shows that MHC-derived peptides are present, albeit in extremely low concentrations. In contrast, urine contains abundant peptides which differ between mouse strains due to genomic variations such as single-nucleotide variations or complex polymorphisms in multigene families as well as in their concentration. Thus, urinary peptides represent a real-time sampling of the expressed genome available for sensory evaluation. It is suggested that peptide variation caused by genomic differences contains sufficient information for individual recognition beyond or instead of an influence of the MHC in mice and other vertebrates.

Polygenic influences on the length of oestrous cycles in inbred mice involve MHC alleles

Genetic influences on female reproductive cycles were analysed in histocompatibility-congenic strains of mice. Oestrous cycles of young, virgin mice of inbred-congenic strains, hybrid crosses (F1), and parental-hybrid backcrosses (F2) were monitored for 3 months. Oestrous cycles were categorized by length (inter-oestrous interval): 4, 5, 6, or 7-14 days. Mice with the following H-2 haplotypes had a greater proportion of 5-day oestrous cycles: H-2b, H-2r, H-2h2, H-2h4, and H-2i5. In contrast, the H-2k and H-2d haplotypes had mostly 4-day oestrous cycles. Influences of H-2 haplotype were seen on two genetic backgrounds, C57BL/10Sn and C3H. Non-H-2 alleles were also implied by different patterns of cycles between strains with the same H-2b haplotype: C57BL/10Sn with predominantly 5-day cycles vs. C57BL/6J with a mix of 4- and 5-day cycles. The genetic basis for strain differences was investigation in F1 hybrids and their backcrosses. F1 hybrids of an H-2b (C57BL/10Sn; 5-day cycles) and an H-2k (B10.BR; 4-day cycles) strain had mostly 5-day cycles, indicating dominance of an H-2b allele(s). However, F1 hybrids from the reciprocal B6 x B10 cross (both H-2b) also display a preponderance of 5-day cycles, indicating dominance of a non-H-2 autosomal allele from the C57BL/10Sn strain. Among F2 mice, a '4-day' phenotype segregated with homozygosity for the k haplotype (P < 0.05, chi 2). These findings demonstrate the influence of genetic differences at the major histocompatibility complex on oestrous cycles.

Susceptibility to murine hepatitis virus (type 3)-induced paralysis is influenced by class I genes of the MHC

Using H-2 recombinant congenic strains of mice, genetic analysis of resistance to murine hepatitis virus type 3 (MHV3)-induced paralysis was performed. It appeared that both H-2K and H-2D, two class I gene regions of the mouse major histocompatibility complex (MHC), can play independent significant roles in the establishment of such resistance.

Age-related down regulation of hepatic cytochrome P1-450, P3-450, catalase and CuZn-superoxide dismutase RNA

The influence of age on liver gene expression was investigated in two strains of H-2 congenic mice. In B10.RIII mice (H-2r), basal P1- and P3-450 RNA levels progressively decreased 65 and 95%, respectively, between 4 and 28 months of age (P less than or equal to 0.05). Polyaromatic hydrocarbon (PAH) induced P1- and P3-450 RNA levels decreased about 50% during this time (P less than or equal to 0.05). In contrast, in C57BL/10 mice (H-2b) little or no change was detected in basal or induced P1- or P3-450 RNA levels. CuZn-superoxide dismutase RNA decreased 80 to 90% between 4 and 9 months of age in B10.RIII mice, while a quantitatively smaller decrease of 50 to 65% was found in C57BL/10 mice (P less than or equal to 0.05). Catalase RNA decreased approximately 80% between 4 and 9 months of age in B10.RIII mice, and a similar decrease was found in C57BL/10 mice. Down regulation of these genes may explain the reduced activities of the cognate hepatic enzymes, and reduced xenobiotic metabolism found in older animals.

Characterization of H-2 congenic strains using DNA markers

Congenic mouse strains are widely used in mapping traits to specific loci or short chromosomal regions. The precision of the mapping depends on the information available about the length of the differential segment--the segment introduced from the donor into the background strain. Until recently, very few markers flanking the differential locus were known and consequently the length of the foreign segment could only be determined imprecisely. Now, in an attempt to construct a map of the mouse chromosome 17, we have produced a set of DNA markers distributed along the chromosome. These markers provide a new opportunity to measure the length of the differential segment of the congenic strains and thus increase their usefulness for gene mapping. Here we examined the DNA of 96 H-2 congenic strains using 30 DNA markers; of these, the most proximal is located roughly 1.5 centiMorgans (cM) from the centromere and the most distal is about 20 cM telomeric from the H-2 complex (the complex itself being some 20 cM from the centromere). The mapping depends on polymorphism among the input strains and can therefore establish only the minimal length of the differential segment. This point is emphasized by the fact that the average observed length of the differential segment is only about one half of the expected values.

Qa-12--a novel determinant of activated T and B lymphocytes

Investigation of the antigenic phenotype of activated lymphocytes using the broadly cross-reactive mAb 6.3.4 revealed two phenotypic alterations as compared with the resting lymphocytes. The Qa specificity Qa-m208 disappears after lectin activation of Qa-m208-positive T lymphocytes. Analysis of Q7 and Q9 transfectants expressing the Qa-2 polypeptides shows that Qa-m208 is an epitope of the Qa-2 antigen. Because the Qa-2 antigens are still expressed on T lymphoblasts which have lost Qa-m208, changes of the Qa-2 molecules occur and result in the loss of certain epitopes. The second phenotypic change that we observed is the appearance of a novel specificity, Qa-12. Its expression is induced by lymphocyte activation and it is expressed on lymphoblasts of both T and B cell origin. The presence of this novel non-ubiquitous antigenic specificity is determined by the Tla region.

The H-2 class II genes and the susceptibility to the development of pulmonary adenoma in mice

To determine the locus in the H-2 complex that affects susceptibility to the development of pulmonary adenomas in mice, H-2 congenic and recombinant strains of mice with A/Wy, BALB/c, C3H, and B10 backgrounds were subjected to treatment with urethane. The average number and the incidence of adenoma foci were recorded five months after the treatment. In H-2 congenic strains on the A/Wy background, the average number of adenoma foci per mouse was significantly higher in mice of the A/Wy, A/J, and A-Tlab (H-2a) strains than in A.BY (H-2b) mice. In BALB/c and C3H congenic strains, the strains carrying the H-2k haplotype were more susceptible than those carrying the H-2b haplotype. In H-2 congenic strains on the B10 background, the average number and incidence of foci was also higher in haplotypes a, h2, k, and j than in haplotypes b, s, f, d, r, h4, i3, i5, and t4. The average numbers of adenoma foci in (A/J X A.BY)F1 (H-2a/H-2b) and (B10 X B10.A)F1 (H-2b/H-2a) were intermediate between the numbers in the parental strains. In [B10.A(4R) X B10.A (3R)]F1 (H-2h4/H-2i3) and [B10.A(4R) X B10.A(5R)]F1 (H-2h4/H-2i5), the numbers of adenoma foci were higher than in resistant parental recombinants. These patterns of response to urethane matched the patterns of the immune response to lactate dehydrogenase-B (LDH-B) and immunoglobulin gamma 2a (IgG2a) proteins. These differences between mice in their susceptibility to the development of pulmonary adenomas is probably due to the polymorphism of the class II genes in the H-2 complex.

A quantitative analysis of H-2 linked effects on hepatic ganglioside composition

We have conducted a quantitative analysis of the gangliosides extracted from brain, spleen, thymus, and liver tissue of 8-week-old male mice from H-2 congenic mouse strains on the B10 background, using high performance thin-layer chromatography (HPTLC). An analysis of variance of replicate samples of liver from strains B10, B10.A, and B10.G revealed that the time of sample and colony of origin were not sources of significant variance but that for N-glycolylated gangliosides GM2, GM1, and GD1a, the differences detected between strains were significant. Particularly important were the differences for GM1: the values of 0.0% for B10, 19.0% for B10.A, and 36.0% for B10.G were each significantly different from the others (P less than 0.0005). Further studies with liver tissue from B10/A H-2 recombinant strains also revealed three significantly different levels of GD1a: less than or equal to 4.0% [B10, B10.A (3R), B10.A (5R), B10.A (18R)], 11.0% (B10.A), and 33% [B10.A (1R), B10.A (2R), B10.A (4R)]. Our findings support prior studies which indicate that a gene linked to the H-2 complex affects hepatic GM2 galactosyltransferase activity. However, they also indicate that the current model, which classifies all strains as possessing either an allele for "high" enzyme activity or a single alternative allele for "low" enzyme activity, is probably oversimplified, since at least three levels of enzyme activity appear to exist as stable phenotypic markers. Moreover, the current model cannot readily account for the three different levels of GD1a observed with B10/A H-2 recombinants. Alternative models are proposed, including the novel suggestion that a distinct H-2 linked gene may affect hepatic GM1 sialyltransferase activity. These findings demonstrate that further study of H-2 linked genes affecting the activities of glycosyltransferases is indicated.

Vitamin A-enhanced cleft palate susceptibility associated with H-2

Pregnant mice from the congenic strains C57BL/10Sn, B10.BR, B10.A/SgSn, B10.A(5R)/SgSn, B10.A(2R)SgSn and B10.A(18R)Sg were fed Purina Laboratory Chow or the same diet plus approximately 400 IU vitamin A daily and given 80 mg/kg dexamethasone intra-peritoneally or a sham injection on the 12th day of pregnancy. It was found that only strains with b alleles between H-2S and H-2D had significantly higher frequencies of isolated cleft palate among their progeny when fed the supplemental vitamin A. The locus appears to be on the centromeric side of a dexamethasone-induced cleft palate gene which has been mapped to the same general area.

Effects of H-2 complex and non-H-2 background on urethane-induced chromosomal aberrations in mice

The incidence of in vivo urethane-induced chromosomal aberrations was examined in H-2 congenic strains of mice with B10 and A backgrounds. Chromosome analysis of bone-marrow cells could divide 7 lines of A.H-2 congenic strains into 2 groups: one with a higher frequency of chromosomal aberrations such as in A/Wy (haplotype H-2a), A/J (H-2a), A.AL (H-2al) and A.TL (H-2tl), and the other consisting of A.TH (H-2t2), A.CA (H-2f), A.BY (H-2b) and A.SW (H-2s). The same tendency was also observed in the spleen cells. Among B10.H-2 congenic mice, B10.A (H-2a), B10.BR (H-2k), B10.A(3R) (H-2i3), B10.A(5R) (H-2i5) and B10.S(9R) (H-2t4) exhibited significantly higher rates of induced chromosomal aberrations than those in B10 (H-2b), B10.S (H-2s), B10.A(2R) (H-2h2), B10.A(4R) (H-2h4) and B10.S(7R) (H-2t2). To determine the effect on non-H-2 genetic backgrounds on urethane-induced chromosomal aberrations, 4 pairs of strains which have the same H-2 haplotypes, such as in B10 vs. A.BY (H-2b), B10.A vs. A/Wy (H-2a), B10.S vs. A.SW (H-2s), and B10.S(7R) vs. A.TH (H-2t2), were compared. The strains with a B10 background exhibited significantly higher frequencies of deletions and lower frequencies of exchanges than the strains with an A background. These data suggested that at least two genes are involved in the regulation of urethane-induced chromosomal aberrations in mice, one of which is mapped between the S and D regions in the H-2 complex, and another not belonging to H-2.

Structure and expression of murine fourth complement component (C4) and sex-limited protein (Slp)

During the past 4 years we have used recombinant DNA technology to build upon previous genetic and biochemical studies of the C4 and Slp genes and their products. We have isolated DNA probes specific for C4 and Slp, determined the complete sequences of C4 and Slp molecules, established the role of liver mRNA levels in determining serum C4 and Slp levels identified the C4 and Slp genes in Balb/c mice, and begun to probe the structures of the C4 and Slp genes in a variety of inbred mouse strains. This work has provided the tools and a framework for future studies aimed at understanding the multiple functions of the C4 protein and the regulatory mechanisms controlling the expression of the C4 and Slp genes.

A component of genetic variation among mice in activity of transmembrane methyltransferase I determined by the H-2 region

The effects of the mouse major histocompatibility complex, H-2, on phospholipid methyltransferase I and II activities were investigated on hepatocyte membranes from inbred, congenic and recombinant strains. Each methyltransferase was assayed individually by measuring the incorporation of radiolabel from S-adenosyl-L-[methyl-3H]methionine into endogenous phospholipids. Our results indicate that H-2 exerted a significant effect on methyltransferase I but not on methyltransferase II activity. Thus, as in lower eukaryotes, two distinct enzymes were involved in methylation of phosphatidylethanolamine (PE) to phosphatidylcholine (PC). In addition, this effect was localized to the K end of the major histocompatibility complex by the use of recombinant haplotypes.

The genetics of hormone-induced cyclic AMP production and phospholipid N-methylation in inbred strains of mice

Genetic variation in hormone-sensitive cyclic AMP production was investigated among inbred strains of mice. Significant strain differences were observed in β-adrenergic- and glucagon-stimulated adenylate cyclase activity. Comparable differences were also found in membrane methyl-transferase I activity in these strains. Our results of studies using F1progeny of high and low strains suggest a dominance of high MT I activity over low MT I activity. Investigation of recombinant inbred lines between the high and low strains indicates that MT I activity is regulated by at least two major genes;H-2-congenic lines of several inbred strains were then used to identify an association between hormone-stimulated MT I activity and the mouse major histocompatibility complex.

Trichinella spiralis: Genetics of worm expulsion in inbred and F1 mice infected with different worm doses

The nematode Trichinella spiralis is rejected from the intestine at a time that is characteristic for each inbred strain of mouse. Previous work (R. G. Bell et al. 1982a) had empirically identified strong, intermediate, and weak phenotypes (NFR, C3H/He, and C57B1/10 mice, respectively) in mice infected with 400 muscle larvae. It is shown that this classification applies to another eight inbred strains: SWR, DBA/2, DBA/1, LP, Bub/Bn--all intermediate, and NZB/BIN, C57L, A, and Mus molossinus--all weak. This phenotypic classification consistently applies with infections of 400-800 muscle larvae. Below doses of 300 muscle larvae, the strain designation of phenotype does not consistently apply. By this it is meant that the relative rejection rate changes for certain strains so that eventually some strains that were strong (NFR) or intermediate (AKR) responders to 400 muscle larvae become weak responders to 50 muscle larvae. Other strains increase their relative rejection time (B10 . BR, B10 . Q) while many do not change (NFS, C3Heb/Fe, DBA/2, DBA/1). The phenomenon is most apparent in inbred parental strains rather than in F1 crosses, and it represents a phenotypic variation in rejection time that is dependent on dose. It is also demonstrated that time of rejection is directly proportional to dose in all inbred and F1 mouse strains that we have examined. Analysis of F1 crosses shows that most have the rejection time of the strongest responding parental line, suggesting simple genetic control of strong, intermediate, and weak responses. Two F1 crosses invalidated this theory. The DBA/1 X C3H/He (intermediate X intermediate) showed a strong response. The additive effects of parental rejection phenotype indicated that these lines could not be genetically identical for intermediate responsiveness. Similarly, the NFR (strong) X B10 . BR (weak) F1 showed intermediate rejection, indicating partial dominance of C57B1/10 genes over the strong responder NFR strain. Neither the primary expulsion time phenotype, phenotypic variation to low doses, or the rejection characteristics of F1 crosses could be ascribed to genes linked to the major histocompatibility complex.

Demonstration of H-2 antigens on preimplantation mouse embryos using conventional antisera and monoclonal antibody

Mouse embryos at the 2-cell, 8-cell, and blastocyst stages of development were examined for the presence of H-2 antigens by immunoperoxidase labeling and transmission electron microscopy. Conventional antisera made in congenic mouse strains were used to study embryos of four different haplotypes: b, a, k, and d. Blastocysts showed uniform heavy labeling of all cells of the trophectoderm, 8-cell embryos showed lighter labeling of only some of the cells, and 2-cell embryos showed no labeling. Similar results were found for all four haplotypes studied. In addition, monoclonal antibody 11-4.1 (anti-Kk) was reacted with homologous (H-2k) and heterologous (H-2b) blastocysts. Positive results with the monoclonal antibody corroborates the concept that H-2 antigens are expressed on early mouse embryos.

Glucocorticoid-induced cleft palate genes in chromosome 17: genetic linkage and mapping analyses

Genes that influence susceptibility to dexamethasone-induced cleft palate and tentatively designated Dep are linked to the major histocompatibility complex H-2 in chromosome 17 of the mouse. Experiments presented refine the map of genes. The results show two or three Dep loci. The two-locus model maps Dep genes to the class II gene E beta and to the chromosomal region between the S and D genes. The three-locus model maps the Dep genes to the chromosomal regions from the centromere to E beta, from E beta to S, and from D to Pgk-2. Experiments were done by comparing the dexamethasone-induced cleft palate dose response of congenic strains with H-2 haplotypes that are recombinants of H-2a and H-2b. The analysis of genetic linkage between H-2 and Dep was expanded to include reciprocal backcrosses. A maternal factor was found to influence the frequency of dexamethasone-induced cleft palate in the backcross fetuses. The factor's origin is associated with the H-2 haplotype of the outcross mother, so the effect is actually a "grandmother effect" that probably is transmitted horizontally. Finally, the sexes were distributed unevenly between the fetuses with cleft palate in two of the congenic strains. This suggests interaction between the H-2-linked Dep genes and a Dep sex-associated gene that modulates susceptibility to dexamethasone-induced cleft palate.

Genetics of palate development

We are beginning to see a tantalizing picture by looking into the "genetic window" on the teratogenesis of cortisone-induced cleft palate and on normal palate development. We must continue to open this window. So far, all strains of mice that have been treated with cortisone do react with induced cleft palate and, from their dose-response behaviors, they appear to react in the same way. It is tempting to conclude that dosage tolerance is the only genetic variation in the reaction. We do not attach any significance to this because we must emphasize the fact that these different strains represent an insignificant sample of the hundreds of genetically different, recognized strains of the mouse. We have emphasized previously that systematic strain surveys must become an active part of teratological genetics in order to obtain an approximation of how much genetic variation exists in a trait in the species (e.g., Biddle, 1981). Now, we need to go beyond strain surveys. Crosses between strains must become part of this activity. Dominance appears to be a property of the homeostatic model of palate development as far as the cortisone probe is concerned, but it may not be a universal property. The significance of dominance and the architecture of gene action can only be interpreted by exploring more strain pairs in the mouse. A study of two or three or four strains is simply inadequate. From the crosses between a limited number of strains, major genetic factors in cortisone reactivity have been identified. These major genetic factors may regulate the homeostatic model of palate development, but we do not know this for a fact. The identification of major genetic factors has moved us to a new horizon; we can move now from a purely descriptive biology to a study of the functional biology of the process of palate development. This move will require not only the molecular probes with which to walk along the specific chromosomes to the major genetic factors but also a library of fully characterized strains of the mouse in which to use these probes. The library of strains that have been genetically characterized for the cleft palate reaction is missing.

Identification and mapping of Lm-1, an Igh-linked locus for a murine alloantigen

Analyzing Igh congenic, Igh recombinant, and recombinant inbred mouse strains with a cytotoxic T-cell assay, we have identified and mapped an Igh-linked locus (Lm-1) that codes for a cell-surface alloantigen (Lm-1). Lm-1 maps 5 units telomeric to Pre-1 and is genetically distinct from previously described Igh-linked loci. The importance of Lm-1 and its possible relationship to other Igh-linked alloantigens is discussed.

A new H-2-linked class I gene whose expression depends on a maternally inherited factor

The maternally transmitted antigen (Mta) is expressed on the cells of most strains of mice. It is a medial histocompatibility antigen, that is, it is recognized by unrestricted cytotoxic T lymphocytes as are major H antigens, but unlike these it is a weak transplantation antigen and does not itself restrict the T-cell recognition of minor H antigens. All other medial H antigens are encoded by genes closely linked to the major histocompatibility complex, H-2 in the mouse. By contrast, Mta appeared to follow extrachromosomal, maternal inheritance. Several substrains of NZB, NZO and non-inbred European NMRI mice are Mta-negative. Females of these strains bear only Mta- offspring, while females of the inbred Mta+ strains bear only Mta+ offspring. Repeated backcrossing from Mta+ females to NZB or NMRI males has shown that, given the right cytoplasmic genes, the chromosomal genes of these Mta- strains permit expression of Mta2. As the Mta type of a mouse cannot be influenced by embryo transfer or foster nursing, we concluded that it was determined by a cytoplasmic factor (Mtf), transmitted through the egg. We now show that a gene, Hmt, closely linked to the H-2 complex, is also required for expression of Mta.

cDNA clone spanning the alpha-gamma subunit junction in the precursor of the murine fourth complement component (C4)

cDNA clones carrying parts of murine fourth complement component (C4, serum substance protein) mRNA sequences have been identified by differential hybridization to mRNA from a high C4-producing strain, B10.WR, and a congeneic low C4 strain, B10.BR, followed by hybrid-selected translation and DNA sequence analysis. One clone, pMLC4/w7-2, encodes an open amino acid reading frame that includes four tandem arginine residues immediately preceding a sequence 85% homologous with the NH2-terminal sequence of the human C4 gamma-chain. The amino acid composition of the predicted sequence upstream of the tandem arginines matches quite closely with the composition of a similar sized peptide at the COOH terminus of the human C4 alpha chain. The latter result raises questions regarding the nature and extent of plasma-mediated postsynthetic processing of the C4 alpha-chain COOH terminus. The results also demonstrate that strain differences in plasma C4 levels (low C4 vs. high C4) reflect differences in steady-state levels of liver C4 mRNA in these strains.

Serum gp70 production regulated by a gene on murine chromosome 7

We mated 129 mice (prototype strain of GIX+) with C57BL/6 mice (prototype strain of GIX-) and thereby identified the gene controlling enhancement of serum gp70 production after lipopolysaccharide (LPS) injection. This gene has been tentatively designated Sgp-2. Sgp-2 is linked with the Hbb locus on chromosome 7. The estimated frequency of recombination between Sgp-2 and Hbb in this setting is about 20%.

H-2-linked regulation of serum gp70 production in mice

By using many congenic strains of C57BL/10 (B10) mice and NZB mice, we have demonstrated a genetic system that controls the production of serum gp70. Our system has been tentatively designated as Sgp-1 and is composed of three phenotypes, Sgp-1a, 1b, and 1c. This system appears to be closely linked to, but not in the H-2 region on chromosome 17. Sgp-1a, which is associated with H-2d, correlates with relatively large amounts of serum gp70 in B10 congenic lines. Sgp-1b, which appeared in most of the H-2 types tested, corresponds with low serum gp70 output in B10 congenic lines and F1 hybrid offspring of B10 and NZB crosses and with increased gp70 production after lipopolysaccharide (LPS) stimulation. Sgp-1c, which is associated with H-2s, also relates to small amounts of serum gp70 in B10 congenic lines and their F1 hybrids from NZB matings, but shows lack of serum gp70 responsiveness to LPS. This failure to accelerate serum gp70 production after injection of LPS is independent of other acute phase responses and polyclonal activation of B cells.