Organic aciduria and butyryl CoA dehydrogenase deficiency in BALB/cByJ mice

A metabolic screening program of inbred strains of mice has detected a marked organic aciduria in the BALB/cByJ strain. Gas chromatographic and mass spectrometric analysis identified large quantities ofn-butyrylglycine plus lesser quantities of ethylmalonic acid. Crosses with the nonexcreting C57BL/6J strain indicate that this condition is inherited as an autosomal recessive trait. Independently from this screening a variant with no detectable enzyme activity of butyryl CoA dehydrogenase (BCD) in liver and kidney of the BALB/cByJ strain but not other BALB/c sublines was discovered. Data from a three-point cross indicated that the null variant maps to the structural locus for the enzyme,Bcd-1, on chromosome 5. The findings indicate that a mutation at or nearBcd-1 in the BALB/cByJ strain resulted in a biochemical abnormality manifest as the BCD deficiency. It is concluded that accumulation of butyryl CoA due to a block in the oxidation of short-chain fatty acids results in an overproduction of organic metabolites leading to the observed organic aciduria. The fact that other BALB/c substrains do not exhibit this abnormality further suggests that this disorder reflects subline divergence within the BALB/c family.This work was supported by NIH Grants RR02512 and GM32592 to the University of Pennsylvania and HD23168, NS17752, and HD08536 to the Children's Hospital of Philadelphia, National Science Foundation Grant BSR 84-18828 to The Jackson Laboratory, and a Postdoctoral Fellowship from the Juvenile Diabetes Foundation International to Dr. Prochazka.     

Mammary tumor modifiers in BALB/cJ mice heterozygous for p53

BALB/c mice are predisposed to developing spontaneous mammary tumors, which are further increased in a p53 heterozygous state. C57BL/6J mice are resistant to induced mammary tumors and develop less than 1% mammary tumors in both wild-type and p53 ^+/− states. To map modifiers of mammary tumorigenesis, we have established F₁ and F₂ crosses and backcrosses to BALB/cJ (N2-BALB/cJ) and C57BL/6J (N2-C57BL/6J) strains. All cohorts developed mammary carcinomas in p53 ^+/− females, suggesting that multiple loci dominantly and recessively contributed to mammary tumorigenesis. We mapped two modifiers of mammary tumorigenesis in the BALB/cJ strain. Mtsm1 (mammary tumor susceptibility modifier), a dominant-acting modifier, is located on chromosome 7. Mtsm1 is suggestive for linkage to mammary tumorigenesis (p = 0.001). We have analyzed the Mtsm1 region to locate candidate genes by comparing it to a rat modifier region, Mcs3, which shares syntenic conservation with Mtsm1. Expression data and SNPs were also taken into account. Five potential candidate genes within Mtsm1 are Aldh1a3, Chd2, Nipa2, Pcsk6, and Tubgcp5. The second modifier mapped is Mtsm2, a recessive-acting modifier. Mtsm2 is located on chromosome X and is significantly linked to mammary tumorigenesis (p = 1.03 × 10⁻⁷). Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

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.     

Liver size and lipid content differences between BALB/c and BALB/cJ mice on a high-fat diet are due,in part,to Zhx2

Mammalian Genome - BALB/cJ mice exhibit considerable phenotypic differences with other BALB/c substrains. Some of these traits involve the liver, including persistent postnatal expression of genes...     

AVP and Glu systems interact to regulate levels of anxiety in BALB/cJ mice

While the roles of glutamic acid(Glu), arginine vasopressin(AVP) and their respective receptors in anxiety have been thoroughly investigated, the effects of interactions among Glu, N-methyl-D-aspartic acid(NMDA) receptor, AVP and a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid(AMPA) receptor on anxiety are still unclear. In the present study, the agonist and antagonist of the NMDA receptor and AMPA receptor, as well as the antagonist of AVP V1 receptor(V1aR) were introduced into BALB/cJ mice by intracerebroventricular microinjection, and the anxiety-like behaviors of the mice were evaluated by open field and elevated plus-maze tests. Compared with C57BL/6 mice, BALB/cJ mice displayed higher levels of anxiety-like behavior. Significant anxiolytic effects were found in the NMDA receptor antagonist(MK-801) and the AMPA receptor or V1 aR antagonist(SSRI49415), as well as combinations of AVP/MK-801 and SSRI49415/DNQX. These results indicated that anxiety-like behaviors expressed in BALB/CJ mice may be due to a coordination disorder among glutamate, NMDA receptor, AMPA receptor, AVP and V1 aR, resulting in the up-regulation of the NMDA receptor and V1 aR and down-regulation of the AMPA receptor. However, because the AMPA receptor can execute its anxiolytic function by suppressing AVP and V1 aR, we cannot exclude the possibility of the NMDA receptor being activated by AVP acting on V1 aR.     

Francisella tularensis Vaccines Elicit Concurrent Protective T- and B-Cell Immune Responses in BALB/cByJ Mice

In the last decade several new vaccines against Francisella tularensis, which causes tularemia, have been characterized in animal models. Whereas many of these vaccine candidates showed promise, it remains critical to bridge the preclinical studies to human subjects, ideally by taking advantage of correlates of protection. By combining in vitro intramacrophage LVS replication with gene expression data through multivariate analysis, we previously identified and quantified correlative T cell immune responses that discriminate vaccines of different efficacy. Further, using C57BL/6J mice, we demonstrated that the relative levels of gene expression vary according to vaccination route and between cell types from different organs. Here, we extended our studies to the analysis of T cell functions of BALB/cByJ mice to evaluate whether our approach to identify correlates of protection also applies to a Th2 dominant mouse strain. BALB/cByJ mice had higher survival rates than C57BL/6J mice when they were immunized with suboptimal vaccines and challenged. However, splenocytes derived from differentially vaccinated BALB/cByJ mice controlled LVS intramacrophage replication in vitro in a pattern that reflected the hierarchy of protection observed in C57BL/6J mice. In addition, gene expression of selected potential correlates revealed similar patterns in splenocytes of BALB/cByJ and C57BL/6J mice. The different survival patterns were related to B cell functions, not necessarily to specific antibody production, which played an important protective role in BALB/cByJ mice when vaccinated with suboptimal vaccines. Our studies therefore demonstrate the range of mechanisms that operate in the most common mouse strains used for characterization of vaccines against F. tularensis, and illustrate the complexity necessary to define a comprehensive set of correlates.     

Isolation of protective T cells from BALB/cJ mice chronically infected with Leishmania donovani

BALB/cJ mice, which are homozygous for Lshs on chromosone 1, are genetically susceptible to Leishmania donovani (S3), but spontaneously reduce their parasite burdens late in the course of infection. Spleens from chronically infected mice (5 to 8 mo) were found to have T cells that responded to leishmanial Ag by proliferating and secreting immune IFN. An IFN-secreting T cell line derived from the spleen of a chronically infected mouse, after boosting with leishmanial Ag and treatment with Pentostam to kill residual parasites, was able to activate macrophages to kill amastigotes in vitro. Furthermore, after adoptive transfer of this cell line, naive BALB/cJ mice challenged with amastigotes demonstrated a 42-fold reduction in parasite burden compared to controls. Four of five clones derived from the protective T cell line secreted IFN and proliferated between days 7 and 14 after Ag stimulation. All clones were Ly1+2-, L3T4+. Another T cell line, which had Ly1+2-, L3T4+ phenotype, was derived from the lymph nodes of s.c. immunized, uninfected mice. It multipled but never produced IFN in response to leishmanial Ag and failed to protect macrophages against L. donovani infection in vitro or in vivo. This nonprotective T cell line and the fifth clone from the protective line, which also did not secrete IFN, proliferated between days 2 and 7 after Ag stimulation. In summary, leishmania-responsive helper/inducer T cells, which produced IFN but were slow to proliferate in response to Ag in vitro and which were able to activate macrophages to reduce amastigotes in vitro and in vivo, are present in chronically infected BALB/cJ mice and may mediate the decrease in parasite burden during chronic infection.     

Plasmodium chabaudi chabaudi: B-1 cell expansion correlates with semiresistance in BALB/cJ mice

The largest obstacle impeding the development of an effective malaria vaccine is the incomplete understanding of how the immune response is regulated during infection. B-1a cells, a poorly understood subcategory of B lymphocytes, produce nonpathologic autoantibodies of low affinity which have been shown to have distinct immunoregulatory capabilities. What the exact activity of B-1a cells are during the course of malaria has yet to be determined. By use of flow cytometry, it was observed that B-1a cells significantly expand by day 3 postinfection in the spleen and peritoneum of Plasmodium chabaudi chabaudi semiresistant BALB/cJ mice, but not until day 8 postinfection in the spleen of P. chabaudi chabaudi fully susceptible BALB/cByJ mice. The activation of B-1a cells was also demonstrated by the measurement of natural autoantibody IgM production from the serum and cultured peritoneal B-1a cells. Infected semiresistant BALB/cJ mice generated higher levels of anti-ssDNA IgM antibodies than infected fully susceptible BALB/cByJ mice. The preliminary data presented here suggest a possible roll of B-1 cells in contributing to the successful survival of murine malarial infection.     

Doc and copia instability in an isogenic Drosophila melanogaster stock

A high degree of heterogeneity and an overall increase in number of insertion sites of the mobile elements Doc and copia were revealed in one substock of an isogenic Drosophila melanogaster stock, while in two other substocks the distribution of copia sites was highly homogenous, but that of Doc sites was again heterogenous. We therefore concluded that copia was unstable in one of the substocks and Doc was unstable in all. Doc instability presumably arose earlier than copia instability. Doc and copia transpositions were directly observed in experiments with one substock. An abundance of copia insertions was revealed in the X chromosome where insertions with deleterious effects are exposed to selection in hemizygous condition. The locations of many other mobile elements (mdg1, mdg2, mdg3, mdg4, 297, B104, H.M.S. Beagle, I, P, BS, FB) were found to be conserved in each substock and did not differ between them, indicating that these mobile elements were stable. This homogeneity is a strong argument against any possibility of inadvertent contamination.     

Differential susceptibility to actively induced experimental allergic encephalomyelitis and experimental allergic orchitis among BALB/c substrains

Experimental allergic orchitis (EAO) and experimental allergic encephalomyelitis (EAE) are animal models of organ-specific autoimmune disease. In this study, BALB/cByJ and BALB/cAnNCr mice were susceptible to both autoimmune diseases whereas BALB/cJ subline mice were resistant. Disease resistance in BALB/cJ mice did not appear to be a reflection of either (i) a nonspecific generalized impairment of cellular immunity or (ii) an alteration in the phenotypic expression of Bordetella pertussis-induced histamine sensitization, a phenotype which has been shown to be associated with susceptibility to both diseases. Susceptibility to both EAE and EAO was inherited as a dominant trait in F1 hybrid animals. Segregation analysis in a (BALB/cByJ X BALB/cJ) X BALB/cJ backcross population suggested that disease resistance may be associated with a single genotypic difference in a common regulatory gene affecting susceptibility to both diseases. Linkage analysis of the backcross population failed to demonstrate an association of disease resistance with the mutant raf-1b allele carried by BALB/cJ mice. The results of these studies support previous observations that multiple genotypic differences may in fact exist in mice of the BALB/cJ subline and that such differences play a significant role in the genetic control of susceptibility to EAE and EAO.     

Phenotypic mechanisms of host resistance against greenbug (Homoptera: Aphididae) revealed by near isogenic lines of wheat

Interactions between biotype E greenbug, Schizaphis graminum (Rondani), and wheat, Triticum aestivum L., were investigated using resistant and susceptible near isogenic lines of the greenbug resistance gene Gb3. In an antixenosis test, the greenbugs preferred susceptible plants to resistant ones when free choice of hosts was allowed. Aphid feeding resulted in quick and severe damage to susceptible plants, which seemed to follow a general pattern spatially and was affected by the position where the greenbugs were initially placed. Symptom of damage in resistant plants resembled senescence. Within-plant distribution of aphids after infestation was clearly different between the two genotypes. Significantly more greenbugs fed on the first (oldest) leaf than on the stem in resistant plants, but this preference was reversed in the susceptible one. After reaching its peak, aphid population on the susceptible plants dropped quickly. All susceptible plants were dead in 10-14 d after infestation due to greenbug feeding. Aphid population dynamics on resistant plants exhibited a multipeak curve. After the first peak, the greenbug population declined slowly. More than 70% of resistant plants were killed 47 d after infestation. Performance of both biotype E and I greenbugs on several Gb3-related wheat germplasm lines were also examined. It seems that the preference-on-stem that was characteristic of biotype E greenbugs on the susceptible plants was aphid biotype- and host genotype-dependent. Results from this study suggested that antixenosis, antibiosis, and tolerance in the resistant plants of wheat might all contribute to resistance against greenbug feeding.     

Altered splenic T cell function of BALB/cByJ mice infected with mouse hepatitis virus or Sendai virus

Mouse hepatitis virus and Sendai virus are among the most common viruses naturally infecting laboratory mice. Concanavalin A-stimulated in vitro proliferative responses of splenocytes were examined after infection of BALB/cByJ mice with the JHM strain of mouse hepatitis virus (MHV-JHM) or Sendai virus. Mice were exposed to these viruses by presumed natural routes (per os or intranasally). Immunodepression was marked but transient among BALB/cByJ mice exposed to MHV-JHM. Among mice exposed to Sendai virus and examined over a 21-day period, spleen cells from only one mouse, sacrificed 10 days postinoculation, exhibited a severely impaired ability to respond to concanavalin A. Lymphokine production by spleen cells from control and infected mice was then assessed. IL 2 was either absent or present at very low levels in culture supernates of concanavalin A-unresponsive spleen cells from MHV-JHM-infected mice. Spleen cells from the single Sendai virus-infected mouse also produced very low levels of IL 2. In contrast, IL 1 was detected in supernatants of all spleen cell cultures derived from control, MHV-JHM-infected, or Sendai virus-infected mice. There was not a clear correlation between concanavalin A responsiveness and the ability of spleen cells to produce interferon-gamma. These results stress the importance of using laboratory mice of known microbiological status for immunologic experiments.     

Estrous cycle effects on behavior of C57BL/6J and BALB/cByJ female mice: implications for phenotyping strategies

Systematic behavioral phenotyping of genetically modified mice is a powerful method with which to identify the molecular factors implicated in control of animal behavior, with potential relevance for research into neuropsychiatric disorders. A number of such disorders display sex differences, yet the use of female mice in phenotyping strategies has been a rare practice because of the potential variability related to the estrous cycle. We have now investigated the behavioral effects of the estrous cycle in a battery of behavioral tests in C57BL/6J and BALB/cByJ inbred strains of mice. Whereas the performance of BALB/cByJ female mice varied significantly depending on the phase of the estrous cycle in the open field, tail flick and tail suspension tests, the behavior of C57BL/6J females, with the exception of the tail suspension performance, remained stable across all four phases of the estrous cycle in all of the tests including open field, rotarod, startle reflex and pre-pulse inhibition, tail flick and hot plate. We also found that irrespective of the estrous cycle, the behavior of C57BL/6J females was different from that of BALB/cByJ groups in all of the behavioral paradigms. Such strain differences were previously reported in male comparisons, suggesting that the same inter-group differences can be revealed by studying female or male mice. In addition, strain differences were evident even for behaviors that were susceptible to estrous cycle modulations, although their detection might necessitate the constitution of large experimental groups.     

Restraint increases prolactin and REM sleep in C57BL/6J mice but not in BALB/cJ mice

Sleep is generally considered to be a recovery from prior wakefulness. The architecture of sleep not only depends on the duration of wakefulness but also on its quality in terms of specific experiences. In the present experiment, we studied the effects of restraint stress on sleep architecture and sleep electroencephalography (EEG) in different strains of mice (C57BL/6J and BALB/cJ). One objective was to determine if the rapid eye movement (REM) sleep-promoting effects of restraint stress previously reported for rats would also occur in mice. In addition, we examined whether the effects of restraint stress on sleep are different from effects of social defeat stress, which was found to have a non-REM (NREM) sleep-promoting effect. We further measured corticosterone and prolactin levels as possible mediators of restraint stress-induced changes in sleep. Adult male C57BL/6J and BALB/cJ mice were subjected to 1 h of restraint stress in the middle of the light phase. To control for possible effects of sleep loss per se, the animals were also kept awake for 1 h by gentle handling. Restraint stress resulted in a mild increase in NREM sleep compared with baseline, but, overall, this effect was not significantly different from sleep deprivation by gentle handling. In contrast, restraint stress caused a significant increase in REM sleep compared with handling in the C57BL/6J mice but not in BALB/cJ mice. Corticosterone levels were significantly and similarly elevated after restraint in both strains, but prolactin was increased only in the C57BL/6J mice. In conclusion, this study shows that the restraint stress-induced increase in REM sleep in mice is strongly strain dependent. The concomitant increases in prolactin and REM sleep in the C57BL/6J mice, but not in BALB/cJ mice, suggest prolactin may be involved in the mechanism underlying restraint stress-induced REM sleep. Furthermore, this study confirms that different stressors differentially affect NREM and REM sleep. Whereas restraint stress promotes REM sleep in C57BL/6J mice, we previously found that in the same strain, social defeat stress promotes NREM sleep. As such, studying the consequences of specific stressful stimuli may be an important tool to unravel both the mechanism and function of different sleep stages.     

Doc and copia instability in an isogenic Drosophila melanogaster stock

A high degree of heterogeneity and an overall increase in number of insertion sites of the mobile elements Doc and copia were revealed in one substock of an isogenic Drosophila melanogaster stock, while in two other substocks the distribution of copia sites was highly homogenous, but that of Doc sites was again heterogenous. We therefore concluded that copia was unstable in one of the substocks and Doc was unstable in all. Doc instability presumably arose earlier than copia instability. Doc and copia transpositions were directly observed in experiments with one substock. An abundance of copia insertions was revealed in the X chromosome where insertions with deleterious effects are exposed to selection in hemizygous condition. The locations of many other mobile elements (mdg1, mdg2, mdg3, mdg4, 297, B104, H.M.S. Beagle, I, P, BS, FB) were found to be conserved in each substock and did not differ between them, indicating that these mobile elements were stable. This homogeneity is a strong argument against any possibility of inadvertent contamination.