Differences in liver ganglioside patterns in various inbred strains of mice

The ganglioside patterns in the liver of different inbred and hybrid strains of mice were investigated. The inbred strains were Balb/cAnNCr1BR, C57BL/6NCr1BR, DBA/2NCr1BR. C3H/HeNCr1BR; the hybrid strain was the Swiss albino. The following major gangliosides were found to be present in mouse liver: GM3-NeuAc; GM3-NeuGl, GM2 [a mixture of one species carrying N-acetylneuraminic acid (NeuAc) and one carrying N-glycollylneuraminic acid (NeuGl)], GM1 and GD1a-(NeuAc,NeuGl). The qualitative and quantitative patterns of liver gangliosides were markedly different in the various inbred strains of mice; in Balb/cAnNCr1BR strain, ganglioside GM2 was preponderant (99.2% of total ganglioside content); in C57BL/6NCr1BR, the major ganglioside was GM2 (90.4%), followed by GM3-NeuAc (5.6%) and GM3-NeuGl (4.0%); in DBA/2NCr1BR, GM2 accounted for 77.1%, GD1a-(NeuAc,NeuGl) 18.9% and GM1 3.1% of gangliosides; in C3H/HeNCr1BR, GM2 constituted 50.6%, GM1 22.8% and GD1a-(NeuAc,NeuGl) 22.1%. In the hybrid Swiss albino mice, liver ganglioside composition markedly varied from one animal to another, GM3-NeuGl, GM2 and GD1a-(NeuAc,NeuGl) being the predominant gangliosides in the various cases.     

Impulsive choice in inbred strains of mice

When humans or non-humans are given a choice between receiving a sooner-smaller (SS) reinforcer, or a later-larger (LL) reinforcer, the choice of a SS reinforcer represents impulsive choice whereas the choice of a LL reinforcer represents self-controlled choice. It has been suggested that both biological and genetic factors influence impulsive/self-control choice in this paradigm. In the present study, the inbred strains of BALB/c, C57BL/6, and DBA/2 mice were given a choice to press one of two levers in an operant chamber. Depending on their choice, mice received either a smaller reinforcer (one pellet delivered after 6s) sooner (SS) or a larger reinforcer (two pellets after 6, 9, 12, 18, or 30s) later (LL). Mice preference for the larger reinforcer decreased with longer delays. More importantly, the BALB/c mice chose the SS reinforcer more often than the C57BL/6 mice under the 9- and 12-s delays, and more often than the DBA/2 mice under the 9-s delay. This indicates that the choice pattern of the BALB/c strain is more "impulsive" than the other strains and suggests that specific gene configurations influence impulsive choice in mice.     

Quiet mutations in inbred strains of mice

The year 2009 is the 100th anniversary of the founding of the first inbred strain of mouse, called DBA. During the last 100 years, inbred strains have proved their value for biomedical research and the number of such strains has mushroomed to over 450, each with different genotypic and phenotypic characteristics and useful for the study of disease and normal function. However, although inbred strains are stable, they are not fixed entities and researchers need to be aware of the phenomena of new mutations and of genetic drift, which occur within all mouse colonies. If the mutations are what we term in this review 'quiet mutations', then they might result in rather unexpected and sometimes tremendously valuable results. Here, we discuss these phenomena and look at how new genomic technologies might help us to detect 'quiet mutations' and use them to our advantage.     

Sex ratio of inbred strains of mice

A study of the sex ratio in mice of the inbred strains (CBA and C3H) and connection of the postimplantation embryonic mortality in mice of these strains with the sex distribution of embryos demonstrated that the sex ratio in these mice was 1:1. Literature and the author's personal data suggested that genetic features of mice of the inbred strains failed to influence significantly the sex ratio of the offspring. The postimplantation embryonic death rate in the C3H mice exceeded that in the CBA mice (14.4 and 9.3%, respectively). However, the balanced sex ratio in mice of these strains points to the absence of selective mortality of the embryos of any one sex during embryogenesis.     

Cryptosporidium infections in inbred strains of mice.

Cryptosporidium, a protozoan parasite of man and animals, is an important etiological agent of diarrhea throughout the world, particularly in children and immunocompromised individuals such as AIDS patients. Unfortunately, because of the lack of both in vivo laboratory models and reliable in vitro parasite culture systems, virtually nothing is known about the immunological events occurring during disease. In order to identify reliable animal models for infection, we studied C. parvum infections in 19 different strains of mice representing 12 H-2 haplotypes: A/J, AKR/J, B10.D2/J, B10.M/J, C3H/HeJ, C57BL/65, C57BL/6J-bgJ, CBA/NJ, DBA/1J, DBA/2J, HRS/J, HTG/J, NZB/B1NJ, NZW/J, P/J, RIII/J, SJL/J, SWR/J, and WB/ReJ, and in one gerbil: Meriones unguiculatus. Fecal samples and histological sections of the intestine taken on day 7 post-Cryptosporidium inoculation indicated that only the beige mouse (C57BL/6J-bgJ) harbored significant numbers of parasites compared to the other strains. The numbers of parasites harbored in these NK cell-deficient beige mice were, however, considerably lower than those seen in neonatal mice. Adult inbred mouse strains susceptible to Cryptosporidium infections are discussed.     

Variation in reproductive isolation across a species range

Reproductive isolation is often variable within species, a phenomenon that while largely ignored by speciation studies, can be leveraged to gain insight into the potential mechanisms driving the evolution of genetic incompatibilities. We used experimental greenhouse crosses to characterize patterns of reproductive isolation among three divergent genetic lineages of Campanulastrum americanum that occur in close geographic proximity in the Appalachian Mountains. Substantial, asymmetrical reproductive isolation for survival due to cytonuclear incompatibility was found among the lineages (up to 94% reduction). Moderate reductions in pollen viability, as well as cytoplasmic male sterility, were also found between some Mountain populations. We then compared these results to previously established patterns of reproductive isolation between these Mountain lineages and a fourth, widespread Western lineage to fully characterize reproductive isolation across the complete geographic and genetic range of C. americanum. Reproductive isolation for survival and pollen viability was consistent across studies, indicating the evolution of the underlying genetic incompatibilities is primarily determined by intrinsic factors. In contrast, reproductive isolation for germination was only found when crossing Mountain populations with the Western lineage, suggesting the underlying genetic incompatibility is likely influenced by environmental or demographic differences between the two lineages. Cytoplasmic male sterility was also limited in occurrence, being restricted to a handful of Mountain populations in a narrow geographic range. These findings illustrate the complexity of speciation by demonstrating multiple, independent genetic incompatibilities that lead to a mosaic of genetic divergence and reproductive isolation across a species range.     

Quantifying patterns in the evolution of reproductive isolation

We present a likelihood-based statistical method for examining the pattern or rate of evolution of reproductive isolation. The method uses large empirical datasets to estimate, for a given clade, the average duration of two phases in the divergence of populations. The first phase is a lag phase and refers to the period during which lineages diverge but no detectable reproductive isolation evolves. The second is an accumulation phase, referring to the period during which the magnitude of reproductive isolation between diverging lineages increases. The pattern of evolution is inferred from the relative durations of these two phases. Results of analyses of postzygotic isolation data indicate significant differences among taxa in the pattern of evolution of postzygotic isolation that are consistent with predictions based on genetic differences among these groups. We also examine whether the evolution of postzygotic isolation is best explained by either of two models for the rate of accumulation: a linear model or a quadratic function as may be suggested by recent studies. Our analysis indicates that the appropriateness of either model varies among taxa.     

Genetic marker patterns of inbred strains of mice at the Cancer Research Institute, Bombay

36 genetic markers were examined in 14 inbred strains of mice maintained at the Cancer Research Institute, Bombay. The genetic marker profiles of these strains when compared with the profiles of similar strains maintained elsewhere revealed discrepancies in 4 of them which are reported and discussed. The results emphasize the importance of genetic monitoring of inbred strains.     

Allele frequencies and diversity parameters of 27 single nucleotide polymorphisms within and across goat breeds

Single‐nucleotide polymorphisms (SNPs) are useful markers for biodiversity assessment, linkage analysis, traceability and paternity testing. To date, there are no available SNPs for goat in the NCBI dbSNP database and only a few are reported in the literature. Within the European Union Econogene project, we characterized 27 SNPs in goats using a targeted‐gene approach. Polymorphisms were identified in a panel of 16 unrelated individuals belonging to eight different goat breeds selected throughout Europe. Genotypes of 30 goats from each of the eight breeds were determined for all the SNPs characterized and diversity measures were estimated. The caprine SNPs described will be a useful complement to the available genome markers.     

Stability of liver nuclear proteins in inbred strains of mice

1. A remarkable similarity in the gel patterns of liver nuclear proteins between four inbred strains of mice (A.CA, B10.A, CBA and DBA/2) was observed. 2. Only a very few quantitative differences were detected in the protein spot patterns of nucleoplasmic (spot of about 41 kDa) and chromatin (spot of about 37 kDa) non-histone proteins between those strains of mice. 3. Comparison of two-dimensional gel patterns of non-histone proteins from males and females revealed a few sex-linked spots. Nucleoplasmic protein with molecular weight of about 59 kDa and chromatin proteins with molecular weights of approximately 47 and 57 kDa were more abundant in liver nuclei of male mouse.