Interacting Genes Control Glycerol-3-Phosphate Dehydrogenase Expression in Developing Cerebellum of the Mouse

The cerebellum of BALB/cJ mice has approximately 2.5 times as much glycerol-3-phosphate dehydrogenase (GPDH) as that of C57BL/6J mice. This difference in enzyme levels, which positively correlates with similar differences in the levels of hybridizable GPDH mRNA, is controlled by at least two unlinked regulatory loci and the structural gene, Gdc-1, located on chromosome 15. These regulatory loci, which act predominantly during the second and third weeks of postnatal cerebellar development and differentiation, have been separated from each other in the CXB recombinant inbred strains of mice. One regulatory locus, Gdcr-1, although unlinked to the structural gene, has an allele in BALB/c mice that preferentially enhances expression of the BALB/c structural allele at Gdc-1. The other locus, Gdcr-2, which may or may not be single, enhances GPDH expression at Gdc-1 irrespective of the allele present, as is commonly observed for loci acting from a distance. Measurements of GPDH mRNA in the recombinant inbred mice suggest that these regulatory genes act by modulating mRNA levels. Accordingly, the regulation of GPDH expression in the cerebellum of mice depends on a complex interaction of unlinked regulatory elements with regulatory elements near the structural gene. Furthermore, since the Gdc-1 locus is expressed in virtually every tissue of the mouse except blood and since the observed genetic variation is restricted to the cerebellum, it is likely that other tissues will have their own distinctive genetic mechanisms for modulating Gdc-1 expression.     

Female-predominant expression of testosterone 16 alpha-hydroxylase ("I"-P-450(16)alpha) and its repression in strain 129/J

Using specific testosterone 16 alpha-hydroxylase activity as the basis for selection of fractions during purification, the cytochrome P-450 ("I"-P-450(16)alpha) has been isolated from livers of phenobarbital-treated 129/J female mice [K. Devore, N. Harada, and M. Negishi (1985) Biochemistry, 24, 5632-5637]. An antibody elicited in rabbits to "I"-P-450(16)alpha was used to determine the amount of hepatic microsomal 16 alpha-hydroxylase activity due to "I"-P-450(16)alpha in untreated females and males of the two mouse strains, 129/J and BALB/cJ. The activities inhibited were 0.03 and 0.3 nmol/min/mg protein in the 129/J and BALB/cJ females, respectively. No significant level of "I"-P-450(16)alpha-dependent activity was detected in the microsomes from males of either mouse strain. Immunoblotting of microsomal proteins with the antibody to "I"-P-450(16)alpha revealed approximately a 10-fold greater amount of a 54-kDa protein in the microsomes from BALB/cJ than from 129/J females (0.03 and 0.26 pmol/micrograms protein, respectively). A cDNA clone (R17) for phenobarbital-inducible rat cytochrome P-450 selected "I"-P-450(16)alpha mRNA of mice, indicating a high degree of homology between the mRNAs of mouse "I"-P-450(16)alpha and phenobarbital-inducible rat cytochrome P-450s. Northern and dot hybridization of total mouse liver poly(A)+ RNA with the R17 cDNA probe indicated that the specific content of the hybridizable mRNA was more than 10 times higher in BALB/cJ females than in males, and that the mRNA level in female 129/J mice was very similar to that of 129/J and BALB/cJ males. The repression of "I"-P-450(16)alpha in 129/J females was inherited as an autosomal recessive trait in 129/J and BALB/cJ pairs as indicated by the levels of mRNA in female F1 offspring and the "I"-P-450(16)alpha-dependent hydroxylase activity. Female and male mice of eight more inbred strains (AKR/J, DBA/2J, C57BL/6J, C3H/HeJ, NZB/J, A/J, CBA/CaJ, and P/J) were tested for levels of mRNA. The results showed that the levels of mRNA were always 5- to 10-fold greater in the females than in the corresponding males, although there was some variation in the mRNA content in the males from the different strains. 129/J females appear to be a genetic variant where the female-predominant expression of the mRNA is repressed.     

Differential pathogenesis of respiratory syncytial virus clinical isolates in BALB/c mice

Airway mucus is a hallmark of respiratory syncytial virus (RSV) lower respiratory tract illness. Laboratory RSV strains differentially induce airway mucus production in mice. Here, we tested the hypothesis that RSV strains differ in pathogenesis by screening six low-passage RSV clinical isolates for mucogenicity and virulence in BALB/cJ mice. The RSV clinical isolates induced variable disease severity, lung interleukin-13 (IL-13) levels, and gob-5 levels in BALB/cJ mice. We chose two of these clinical isolates for further study. Infection of BALB/cJ mice with RSV A2001/2-20 (2-20) resulted in greater disease severity, higher lung IL-13 levels, and higher lung gob-5 levels than infection with RSV strains A2, line 19, Long, and A2001/3-12 (3-12). Like the line 19 RSV strain, the 2-20 clinical isolate induced airway mucin expression in BALB/cJ mice. The 2-20 and 3-12 RSV clinical isolates had higher lung viral loads than laboratory RSV strains at 1 day postinfection (p.i.). This increased viral load correlated with higher viral antigen levels in the bronchiolar epithelium and greater histopathologic changes at 1 day p.i. The A2 RSV strain had the highest peak viral load at day 4 p.i. RSV 2-20 infection caused epithelial desquamation, bronchiolitis, airway hyperresponsiveness, and increased breathing effort in BALB/cJ mice. We found that RSV clinical isolates induce variable pathogenesis in mice, and we established a mouse model of clinical isolate strain-dependent RSV pathogenesis that recapitulates key features of RSV disease.     

Genetic and dietary interactions in the regulation of HMG-CoA reductase gene expression.

Inbred strains of mice exhibit large genetic variations in hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity. A tissue-specific genetic variation between the strains BALB/c and C57BL/6, resulting in about 5-fold higher levels in hepatic reductase activity in strain C57BL/6, was examined in detail. The activity difference between these two strains could be explained entirely by differences in hepatic reductase mRNA levels. In genetic crosses, the variation segregated as a single major Mendelian element. Surprisingly, the mode of inheritance was recessive since F1 mice exhibited the BALB/c levels of enzyme activity. Despite the fact that the rates of hepatic sterol synthesis also differed between the strains by a factor of about five, the altered hepatic reductase expression did not significantly influence plasma lipoprotein levels. The response to a high cholesterol, high fat diet between the strains was remarkably different. Thus, in BALB/c mice, both hepatic reductase activity and mRNA levels were affected only slightly, if at all, by cholesterol feeding, while in strain C57BL/6 mice both were reduced more than 10-fold by cholesterol feeding. Several lines of evidence, including analysis of cis-acting regulatory elements, the nonadditive mode of inheritance, and genetic studies of the HMG-CoA reductase gene locus on mouse chromosome 13, support the possibility that the variation in reductase expression is not due to a mutation of the structural gene but, rather, is determined by a trans-acting factor controlling reductase mRNA levels. The variation provides a striking example, at the molecular level, of the importance of dietary-genetic interactions in the control of cholesterol metabolism.     

Immune responses to the 18-kDa protein of Mycobacterium leprae. Similar B cell epitopes but different T cell epitopes seen by inbred strains of mice.

Antibody responses to the 18-kDa protein of Mycobacterium leprae have been analyzed in different strains of mice. High, intermediate, and low responder strains have been identified and these response patterns show clear linkage to genes encoded in the H-2 complex. Three peptides, residues 1-50, 51-100, and 101-148 have been synthesized, as well as a series of 20-mer peptides, which span the entire 18-kDa protein. Repeated immunization of different strains of mice with the 18-kDa protein resulted in IgG responses to epitopes found on all three synthetic peptides. Immunization of BALB/cJ and B10.BR mice, two high responder strains, with 18-kDa protein resulted in high levels of IgG antibody to epitopes found on peptides 1-20, 16-35, 31-50, 46-65, and 76-95. B10.BR mice also contained IgG that bound peptide 61-80 and BALB/cJ mice produced IgG that bound peptide 91-110. Although B10.BR mice produced IgG that bound the 50-mer peptide 101-148, this IgG was not detected by binding to peptides 91-110, 106-125, 121-140, and 131-148. Immunization of B10.BR mice with individual overlapping 20-mer peptides as Ag revealed that peptides 1-20, 16-35, 31-50, and 76-95 elicited high titers of IgG that bound both the immunizing peptide as well as 18-kDa protein. As these peptides induce antibody synthesis they must contain both B cell and T cell epitopes. By contrast, immunization of BALB/cJ mice with the same 20-mer peptides, all of which contain B cell epitopes for this strain, failed to elicit IgG responses with one exception. Peptide 91-110 induced IgG that bound peptide 91-110, but not the intact 18-kDa protein. We conclude that peptides 1-20, 16-35, 31-50, and 76-95 either lack T cell epitopes for BALB/cJ mice, or activate different T cell subpopulations in the two strains. We suggest that the induction of IgG responses to small peptide Ag is an in vivo assay of the activity of Th2 cell subpopulations.     

Inhibition of nitric oxide synthesis increases mortality in Sindbis virus encephalitis.

Sindbis virus (SV) is an alphavirus that causes acute encephalomyelitis in mice. The outcome is determined by the strain of virus and by the age and genetic background of the host. The mortality rates after infection with NSV, a neurovirulent strain of SV, were as follows v: 81% (17 of 21) in BALB/cJ mice; 20% (4 of 20) in BALB/cByJ mice (P < 0.001); 100% in A/J, C57BL/6J, SJL, and DBA mice; and 79% (11 of 14) in immunodeficient scid/CB17 mice. Treatment with Nomega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthetase (NOS) inhibitor, increased mortality to 100% (P < 0.05) in NSV-infected BALB/cJ mice, to 95% (P < 0.001) in BALB/cByJ mice, and to 100% in scid/CB17 mice. BALB/cJ and BALB/cByJ mice had similar levels of inducible NOS mRNA in their brains, which were not affected by L-NAME or NSV infection. Brain NOS activity was similar in BALB/cJ and BALB/cByJ mice before and after infection and was markedly inhibited by L-NAME. NSV replication in the brains of BALB/cJ mice, BALB/cByJ mice, and mice treated with L-NAME was similar. Treatment of N18 neuroblastoma cells with NO donors S-nitroso-N-acetylpenicillamine or sodium nitroprusside in vitro before infection increased cell viability at 42 to 48 h compared with untreated NSV-infected N18 cells with little effect on virus replication. These data suggest that NO protects mice from fatal encephalitis by a mechanism that does not directly involve the immune response or inhibition of virus growth but rather may enhance survival of the infected neuron until the immune response can control virus replication.     

Genetic regulation of testosterone 15 alpha-hydroxylase (cytochrome P-450(15)alpha) in renal microsomes of female mice

P-450(15)alpha is a form of cytochrome P-450 purified from liver microsomes of female 129/J mice that is specific for oxidation of testosterone to its 15 alpha-hydroxylated product. Testosterone 15 alpha-hydroxylase activity that was inhibited by anti-P-450(15)alpha antibody was approximately 50 times higher in renal microsomes from 129/J than in BALB/cJ females. Western blots of renal microsomes using anti-P-450(15)alpha antibody showed the presence of immunoreactive protein with a molecular weight identical with that of hepatic P-450(15)alpha in 129/J but not in BALB/cJ female mice. To investigate the genetic basis for the strain differences in this activity, the distribution of P-450(15)alpha-dependent testosterone 15 alpha-hydroxylase activity in renal microsomes from individual females of 129/J and BALB/cJ, of F1 offspring of these strains, and of F1 back-crosses to the progenitor strains were determined. The results were consistent with a sex-related autosomal dominant regulation of the higher activity in 129/J females by a single locus, designated Rsh (regulation of steroid hydroxylase). The amounts of immunochemically cross-reactive P-450(15)alpha protein were linearly correlated with testosterone 15 alpha-hydroxylase activities in renal microsomes from Rsh heterozygotes and homozygotes. At least twice as much mRNA, which hybridized with the cDNA clone for hepatic P-450(15)alpha, was detected in 129/J and 129CF1/J compared to BALB/cJ female kidneys. The evidence suggests a pretranslational regulation of the P-450(15)alpha isozyme in the female mouse kidney by the Rsh locus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic Determination of the Developmental Program for Mouse Liver β-GALACTOSIDASE: Involvement of Sites Proximate to and Distant from the Structural Gene

The identification and mode of action of genetic loci that program gene expression during development are important for understanding differentiation in higher organisms. Previous work from this laboratory has identified two patterns for the postnatal development of liver beta-galactosidase among inbred mouse strains: type I, where activity levels remain constant after about 30 days of age, is found in strains DBA/2J, CBA/J, and BALB/cJ, among others; type II, where activity levels increase between 25 and 50 days of age to reach a new adult level, is found in strain C57BL/6J and related strains. It has been shown that the type I vs. type II developmental difference between strains C57BL/6J and DBA/2J is due to variation at a locus, Bgl-t, that maps with the beta-galactosidase complex, [Bgl], on chromosome 9. In the present study, we have confirmed the existence of Bgl-t as a temporal locus within [Bgl] by analysis of both a congenic strain carrying the beta-galactosidase complex of strain CBA/J in the C57BL/6J genetic background and a cross of strains CBA/J and C57BL/6J. The existence of additional temporal loci for beta-galactosidase that segregate independently of the structural gene and participate in determination of the type I vs. type II difference was revealed by analysis of: (1) a congenic strain containing the beta-galactosidase complex of strain BALB/cJ in the C57BL/10Sn background; (2) recombinant inbred lines derived from progenitor strains C57BL/6ByJ and BALB/cByJ; and (3) a genetic cross between strains C57BL/6ByJ and BALB/cByJ. Thus, for these pairs of strains, the type I vs. type II developmental difference is due to variation at a temporal locus (or loci) unlinked to the enzyme structural gene, and not at Bgl-t. These facts, together with information gathered from an examination of the distribution of beta-galactosidase phenotypes among over 100 inbred strains (Breen, Lusis and Paigen 1977), have led us to conclude that the postnatal developmental pattern for liver beta-galactosidase is determined by a set of interacting temporal genes. One of these, Bgl-t, is located within [Bgl], and one or more are separable from [Bgl] by recombination. A possible mode of interaction among the temporal and instructural loci is suggested.     

Regulation of polyunsaturated fat induced postprandial hypercholesterolemia by a novel genePHC-2

Inbred mouse strains vary in susceptibility or resistance to dietary induced atherosclerosis. To investigate the effect of polyunsaturated fat feeding on postprandial serum cholesterol levels, in C57BL/67 (B6) and BALB/cJ inbred mice, we fed by stomach gavage previously fasted mice, a mixture containing 30% sunflower oil, 5% cholesterol, 2% sodium cholate and 0.5% choline chloride. The most significant difference in serum cholesterol levels between B6 and BALB/cJ mouse strains was observed at 2 h postfeeding. Susceptible B6 strain mice had a 41% postprandial increment in serum cholesterol. The resistant BALB/cJ strain had an insignificant 16% rise in serum cholesterol, at 2 h. We next examined eight other inbred mouse strains, to identify the gene(s) that regulate the observed 2 h postprandial hypercholesterolemia response, in the susceptible B6 mouse strain. Only the C57BR/cdJ and C57L/J strains developed postprandial hypercholesterolemia, at 2 h. The C57BR/cdJ strain had a 20% increase and the C57L/J strain a 62% increase in postprandial serum cholesterol levels. From this result, we found that the postprandial hypercholesterolemic response to an acute polyunsaturated fat-cholesterol feed, cosegregated with the a allele at the Gpd-1 and Ahd-1 loci, on mouse chromosome 4. In this study, non-responsiveness cosegregated with the b allele at the Gpd-1 and Ahd-1 loci. Thus polyunsaturated fat-cholesterol induced postprandial hypercholesterolemia appeared to be genetically determined by a gene located between the Gpd-1 and Ahd-1 loci, in mice. The putative gene regulating polyunsaturated fat-cholesterol induced post-absorptive hypercholesterolemia was designated Phc-2. Further studies with (BALB/cJ×C57BL/6J) Recombinant Inbred strains mapped the Phc-2 gene to a 2 cM region, within the Gpd-1 and Ahd-1 chromosomal segment, between the Pgd and Gpd-1 loci, on mouse chromosome 4.Abbreviations B6 C57BL/6J - HDL High Density Lipoprotein - LDL Low Density Lipoprotein - Phe Postprandial Hypercholesterolemia - PUFA-C Polyunsaturated Fat with Cholesterol - VLDL Very Low Density Lipoprotein     

Genetic dissection of intermale aggressive behavior in BALB/cJ and A/J mice

Aggressive behaviors are disabling, treatment refractory, and sometimes lethal symptoms of several neuropsychiatric disorders. However, currently available treatments for patients are inadequate, and the underlying genetics and neurobiology of aggression is only beginning to be elucidated. Inbred mouse strains are useful for identifying genomic regions, and ultimately the relevant gene variants (alleles) in these regions, that affect mammalian aggressive behaviors, which, in turn, may help to identify neurobiological pathways that mediate aggression. The BALB/cJ inbred mouse strain exhibits relatively high levels of intermale aggressive behaviors and shows multiple brain and behavioral phenotypes relevant to neuropsychiatric syndromes associated with aggression. The A/J strain shows very low levels of aggression. We hypothesized that a cross between BALB/cJ and A/J inbred strains would reveal genomic loci that influence the tendency to initiate intermale aggressive behavior. To identify such loci, we conducted a genomewide scan in an F2 population of 660 male mice bred from BALB/cJ and A/J inbred mouse strains. Three significant loci on chromosomes 5, 10 and 15 that influence aggression were identified. The chromosome 5 and 15 loci are completely novel, and the chromosome 10 locus overlaps an aggression locus mapped in our previous study that used NZB/B1NJ and A/J as progenitor strains. Haplotype analysis of BALB/cJ, NZB/B1NJ and A/J strains showed three positional candidate genes in the chromosome 10 locus. Future studies involving fine genetic mapping of these loci as well as additional candidate gene analysis may lead to an improved biological understanding of mammalian aggressive behaviors.     

Differential DNA-repair activity in prespermiogenic cells of various mouse strains

The present report demonstrates differential DNA-repair activity among 14 strains of immature (20 ± 2 days old) male mice (inbred strains: C57BL/6J, RF/J, Nude homo/nu, RIII/2J, Pl/J, AKR/J, Nude hetro/nude, C3H/HeJ, SWR/J, SM/J, ST/J, LP/J, BALB/cJ and random-bred strain: CD-1). The prespermiogenic cells were isolated and enriched by collagenase-trypsin digestion of seminiferous tubules and subsequent 3% albumin-gradient centrifugation. Enriched prespermiogenic cells demonstrated a viabiilty greater than 95% by trypan blue exclusion criteria. For in vitro unscheduled DNA synthesis (UDS) determination, prespermiogenic cells (10⁶ cells/ml) were incubated with methyl methanesulfonate (0.4 mM) in the presence of 20 mM hydroxyurea (HU). At 20 mM HU concentration, 90% of S-phase DNA activity in prespermiogenic cells was inhibited and thus, the net UDS activity following MMS exposure was readily determined. MMS-induced UDS activity in the CD-1 mouse strain was both linear up to 4 h of incubation and dose-dependent at 4 h incubation. The apparent K_m for MMS-induced UDS activity in prespermiogenic cells was approx. 1.8 × 10^?4 M. Of the 14 mice strains tested, C57BL/6J and RF/J exhibited the highest DNA-repair activity, while BALB/cJ, LP/J, and ST/J showed the lowest. A maximal difference in UDS activity fo 3.5-fold was observed between C57BL/6J and BALB/cJ. Furthermore, a 2.5-fold difference was also noted between RF/J and LP/J mouse strains. Thus, wide variations in DNA-repair activity among 14 mouse strans were clearly demonstrated. Whether genetically select mouse strains with the lowest DNA-repair activity should have greater sensitivity toward environmental mutagens needs to be tested.     

Genetic analysis of strains C57BL/6J and BALB/cJ for Ath-1, a gene determining atherosclerosis susceptibility in mice

We previously reported that mice have at least one major gene determining atherosclerosis susceptibility, Ath-1. Susceptible alleles of Ath-1 are found in strain C57BL/6J and are associated with relatively low levels of high-density lipoprotein cholesterol (HDL-C) when these mice are fed an atherogenic diet. Resistant alleles of Ath-1 are found in strains C3H/HeJ and BALB/cJ and are associated with relatively high levels of HDL-C. Data reported earlier from the set of seven recombinant inbred (RI) strains, derived from C57BL/6By and BALB/cBy, showed that these parental strains differed at Ath-1. However, due to the limited number of RI strains, it was not possible to determine with certainty whether Ath-1 was the only major gene determining atherosclerosis susceptibility in these two strains or to determine its map position accurately. In this report, examination of F1, F2, and backcross progeny from a cross between C57BL/6J and BALB/cJ demonstrates that Ath-1 is the major gene determining atherosclerotic lesion formation and HDL-C levels in female mice. The data from male animals suggest that environmental factors or modifying genes also influence male HDL-C levels and thus partly obscure the Ath-1 phenotype. HDL-C levels in F1 progeny resemble the BALB/c parent. The data from the cross provide confirmatory evidence that Ath-1 is linked to Alp-2 on chromosome 1 with a map distance of 4.8 +/- 2.3 (SE). Combining these data with a previous cross between strain C57BL/6 and strain C3H/HeJ gives a map distance between Ath-1 and Alp-2 of 4.9 +/- 1.8 based on 7 crossovers found among 144 tested chromosomes.     

Genetic control of immune responses to the 18-kDa protein of Mycobacterium leprae. Different TH1 subsets may be involved in proliferative and delayed-type hypersensitivity responses.

In vitro and in vivo responses to the 18-kDa protein of Mycobacterium leprae have been analysed in different strains of mice. Lymphocytes from BALB/cJ (H-2d), BALB.B (H-2b), B10.BR (H-2k), and B10.M (H-2f) mice primed with 18-kDa protein yielded high T cell proliferative responses, while those from C57BL/10J (H-2b) mice yielded lower responses. Both H-2 and non-H-2 genes contributed to the magnitude of responsiveness. F1 mice from high and low responder strains showed high responsiveness to the 18-kDa protein. Supernatants from lymph node cell cultures prepared from 18-kDa protein-immunised BALB/cJ, B10.BR, and C57BL/10J mice contained IL-2 but no IL-4, indicating that activated T cells from both high and low responder mice were of a TH1 phenotype. Cell cultures from low responder C57BL/10J mice produced less IL-2 than those from high responders. The low responsiveness to the 18-kDa protein in proliferative assays might be due to a low frequency of antigen-specific T cells in the C57BL/10J mouse strain. BALB/cJ, C57BL/10J, and F1 (BALB/cJ x B10.BR) mouse strains were tested for in vivo DTH reactions to the 18-kDa protein. All strains, including C57BL/10J, were high DTH responders. Although DTH effector cells and 18-kDa protein-specific proliferative T cells belong to the TH1 subset, our data comparing high and low responder status indicate that distinct TH1 subpopulations are stimulated in response to the 18-kDa protein of M. leprae.     

Association of mouse fibrinogen-like protein with murine hepatitis virus-induced prothrombinase activity.

Previously, we demonstrated induction of a unique macrophage prothrombinase during infection of BALB/cJ mice by mouse hepatitis virus strain 3 (MHV-3). By immunologic screening, a clone representing this prothrombinase was isolated from a cDNA library and sequenced. The sequence identified this clone as representing part of a gene, musfiblp, that encodes a fibrinogen-like protein. Six additional clones were isolated, and one clone, p11-3-1, encompassed the entire coding region of musfiblp. Murine macrophages did not constitutively express musfiblp but, when infected with MHV-3, synthesized musfiblp-specific mRNA. musfiblp mRNA induction was earlier and significantly greater in BALB/cJ than A/J macrophages. Prothrombinase activity was demonstrated when musfiblp was expressed from p11-3-1 in RAW 264.7 cells. These data suggest that musfiblp encodes the MHV-induced prothrombinase.     

Taenia taeniaeformis: early inflammatory response around developing metacestodes in the liver of resistant and susceptible mice I. Identification of leukocyte response with monoclonal antibodies

Female BALB/cJ (resistant), C3H/HeJ (intermediate resistant), and C3H/HeDub (susceptible) inbred mice, 4-5 wk old, were infected with Taenia taeniaeformis. Liver sections were stained by an immunoperoxidase technique (avidin-biotin complex, ABC) for the differentiation antigens Lyt-1, Lyt-2, Mac-1, Mac-2, Mac-3, and B220. Binding of ABC to the cytoplasm of hepatocytes around the developing parasite was observed at 4 days postinfection (PI) in all 3 strains of mice, persisting in BALB/cJ and C3H/HeJ liver sections at 5 and 6 days PI, suggesting the presence of high concentrations of biotin, a fatty acid synthesis mediator. Two cell populations were labeled with B220 monoclonal antibodies: lymphocytes and polymorphonuclear (PMN) cells. At 4 days PI the number of labeled PMN cells peaked in infected C3H/HeJ and BALB/cJ mice; however a low number of PMN cells were labeled in infected C3H/HeDub mice. Few lymphocytes bound the B220 antibody in either BALB/cJ, C3H/HeJ, or C3H/HeDub infected mice. The number of Mac-1+ cells detected in infected C3H/HeJ and BALB/cJ liver sections were similar whereas fewer Mac-1+ cells were present in infected C3H/HeDub mice. Mac-2+ cells appeared in high numbers around the growing parasite at 5 and 6 days PI in the liver of C3H/HeDub mice, but not in the liver of BALB/cJ mice. Mac-3+ cells followed a similar pattern to that of the cell population defined by Mac-2. Few Lyt-1+ and Lyt-2+ cells were detected around the parasite site in the 3 strains of mice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rip locus: regulation of female-specific isozyme (I-P-450(16 alpha) of testosterone 16 alpha-hydroxylase in mouse liver, chromosome localization, and cloning of P-450 cDNA

The constitutive expression of phenobarbital-inducible mouse cytochrome P-450 (I-P-450(16 alpha) at the mRNA level and its associated testosterone 16 alpha-hydroxylase activity in liver microsomes was a female characteristic in many inbred mice, including BALB/cJ, A/HeJ, and C57BL/6J. This sex-dependent constitutive expression of the mRNA and enzyme activity was severely reduced in females of mouse strain 129/J. The distribution patterns of the mRNA and activity levels in individual offspring of F1, F2, and F1 backcrosses to progenitors, generated from crosses between 129/J and BALB/cJ mice, indicated that the female-specific expression of I-P-450(16 alpha) is an autosomal dominant trait under the regulation of a sex-limited single locus. It was found that the genotypes of this locus exhibited concordance with that of the coumarin hydroxylase locus (Coh locus) in eight out of nine 9 X A recombinant inbred strains, suggesting the localization of this sex-limited locus on chromosome 7. We propose Rip (regulation of sex-dependent, constitutive expression of phenobarbital-inducible P-450) as the name of this sex-limited locus. With the use of the rat P-450e cDNA probe, a cDNA library from liver poly(A+) RNA of BALB/cJ was screened, and three distinct cDNAs (pf3, pf26, and pf46) were selected on the basis of their restriction patterns. Nucleotide sequences of the cDNAs revealed that pf3 and pf46 are clones overlapped, with the exception that the 27-bp DNA is inserted in the coding region of pf46. The nucleotide sequence (named pf3/46) obtained from the overlapping sequences of pf3 and pf46 contained 1473 or 1500 bp of open-reading frame, and the deduced amino acid sequence shared 93% similarity with those of rat P-450b. The 27-bp insertion resulted in nine extra amino acids just in front of the cysteine residue, the fifth ligand for heme binding. The mRNA with 27-bp insertion was ubiquitously present in other inbred mice such as A/HeJ and C57BL/6J, but not in 129/J. S-1 nuclease analysis estimated a ratio of p46 and pf3 to be 1:50. Nucleotide and deduced amino acid sequences of the 1473-bp open-reading frame in pf26 possessed 83% similarity to those of pf3/46. Hybridizations of oligonucleotide probes (pf26-cu and pf3/46-cu) specific to either pf26 or pf3/46 with liver poly(A+) RNA from males and females of BALB/cJ, 129/F, and F1 offspring demonstrated that the expression of pf26, but not pf3/46, mRNA was associated with the autosomal dominant inheritance of I-P-450(16 alpha).(ABSTRACT TRUNCATED AT 400 WORDS)     

cis-acting determinants of basal and lipid-regulated apolipoprotein A-IV expression in mice

The levels of apolipoprotein A-IV (apoA-IV) mRNA are regulated by dietary lipid in the liver of both the mouse and rat. Thirteen different inbred mouse strains were fed a high lipid diet, and the effect on apoA-IV liver mRNA levels was examined. It was found that each strain responded in one of two ways. Mice of four strains had higher liver apoA-IV mRNA levels as compared with syngeneic mice fed a normal chow diet. Mice of the other nine strains had decreased liver apoA-IV mRNA levels as compared with syngeneic mice fed a normal chow diet. Using F1 hybrids between mice from BALB/c, C3H, and C57BL/6 and between 129 and C57BL/6, as well as recombinant inbred strains derived from a cross between BALB/c and C57BL/6, we have shown that both the normal level of liver apoA-IV mRNA in the chow-fed mice and the lipid-dependent regulation of apoA-IV mRNA levels are controlled by cis-acting genetic elements. The apoA-IV mRNA levels in mice fed a normal diet varied dramatically among strains, with the largest difference (90-fold) being between the 129/J inbred strain and the C57BL/6J strain. In addition, we have examined the expression of apoA-IV during mouse development. ApoA-IV mRNA is expressed early in mouse liver (16 days postcoitum), whereas others have shown previously that rat liver apoA-IV mRNA is undetectable until 14 days after birth. ApoA-IV mRNA levels in the intestine and apoA-I mRNA levels in the liver and intestine, by contrast, mirror the pattern seen in the rat.     

Comparison of allergic lung disease in three mouse strains after systemic or mucosal sensitization with ovalbumin antigen

Murine models of allergic lung disease have many similar traits to asthma in humans and can be used to investigate mechanisms of allergic sensitization and susceptibility factors associated with disease severity. The purpose of this study was to determine strain differences in allergic airway inflammation, immunoglobulin production, and changes in respiratory responses between systemic and mucosal sensitization routes in BALB/cJ, FVB/NJ, and C57BL/6J, and to provide correlations between immune and pathophysiological endpoints. After a single intranasal ovalbumin (OVA) challenge, all three strains of mice systemically sensitized with OVA and adjuvant exhibited higher airflow limitation than non-sensitized mice. No changes were seen in mice that were pre-sensitized via the nose with OVA. Systemic sensitization resulted in an elevated response to methacholine (MCH) in BALB/cJ and FVB/NJ mice and elevated total and OVA-specific IgE levels and pulmonary eosinophils in all three strains. The mucosal sensitization and challenge produced weaker responses in the same general pattern with the C57BL/6J strain producing less serum IgE, IL5, IL13, and eosinophils in lung fluid than the other two strains. The converse was found for IL6 where the C57BL/6J mice had more than twice the amount of this cytokine. The results show that the FVB/NJ and BALB/cJ mice are higher Th2-responders than the C57BL/6J mice and that the levels of pulmonary eosinophilia and cytokines did not fully track with MCH responsiveness. These differences illustrate the need to assess multiple endpoints to provide clearer associations between immune responses and type and severity of allergic lung disease.