Epigenetic formation of lactate dehydrogenase isozymes in the house mouse, Mus musculus.

The origin of mouse lactate dehydrogenase (LDH) sub-bands was investigated by using our miniaturized polyacrylamide gel electrophoretic apparatus. Mouse LDH isozymes are generated by combinations of three types of A subunit, the primary type and two epigenetically modified forms. These are designated A1, A2, and A3 in the order of their electrophoretic mobilities towards the anode. The A1 subunit arises from the covalent binding of molecules of glutathione through disulfide bonds to the original subunit, A3. The A2 subunit arises from the covalent binding of molecules of cysteine through disulfide bonds to the A3 subunit. All isozymes can be explained as tetramers composed of the three kinds of A subunit (A1, A2, or A3) in combination with B subunits to yield a total of 35 isozymes. The kinetic properties of these sub-bands were also examined. There was no difference between A24 and A34 in the Km for pyruvate and for lactate. Thermostability at 56 degrees C was greater for A34 than for A24. The activities of tetramers at the electrophoretic position of A3B1 and A4 in extracts containing all five isozymes were increased by treatment of the extracts with high concentrations of reduced glutathione or cysteine with the concomitant disappearance or decrease in activity of tetramers at the position of B4 and A3B1. These results suggest that, in the presence of reduced glutathione or cysteine, LDH isozymes containing the B subunit are first dissociated and then the A subunits are preferentaially recombined.     

Studies on salmonellosis in the house mouse, Mus musculus.

Salmonellae were isolated from the faeces from 17 of 170 (10%) wild house mice. Salmonella typhimurium was isolated from 10, S. typhimurium, var. Copenhagen from 2, S. thompson from 1, and S. muenchen from 4. It was concluded that house mice could be a reservoir of infection and play an important role in human and animal salmonellosis.     

The genetics of an electrophoretic variant of an erythrocytic protein in the house mouse (Mus musculus)

An electrophoretic mobility variant of a protein band anodal to haemoglobin in alkaline starch gels was found in wild house mouse populations in South Australia. Most wild mice and all inbred lines examined are homozygous for the Erp-1 ^a allele at the locus controlling this variation. The rare allele Erp-1 ^b, which has a frequency of about 1% in South Australia, produces a protein band of slower mobility in alkaline gels. Homozygotes show one protein band whilst the heterozygote has three bands. The Erp-1 protein does not appear to be haemoglobin or carbonic anhydrase. The Erp-1 locus is closely linked to Es-1 on chromosome 8 with a recombination fraction of 6.04 ± 1.32%.     

Genetic differences in alteration of albumin in the house mouse,Mus musculus

Two strains of mice were shown to differ in relative proportion of two major protein bands of liver under acid conditions of electrophoresis. Genetic control was autosomal and by a pair of dominant and recessive genes. The difference was observed only if liver homogenates were extracted by treating with dilute acid and alkali. The two protein bands were identified as albumin on the basis of electrophoretic migration, molecular weight, and immunological response. No differences were found between strains in relative amounts of comparable bands of plasma. However, in studies with extraction of mixtures, liver homogenates of one strain but not another were capable of converting a large proportion of albumin from several sources to a faster-migrating form. It was concluded that the strains differ in a factor in liver capable of causing a secondary modification of the albumin molecule.     

Organ specific expression of esterase-6 in the house mouse,Mus musculus

Summary Esterase-6 in fresh homogenates of heart muscle and testis of the house mouse shows a two band (C allele) or three band (A allele) pattern in disc electrophoresis. These primary bands generated a series of secondary bands upon lowering the pH of the homogenates, and the secondary pattern, possibly resulting from partial proteolysis, was seen in varying degrees in fresh homogenates from a range of organs. Interrelationships between the primary and secondary bands were demonstrated by isoelectric focusing. The esterase-6 content of twenty different organ homogenates was estimated from electrophoretic gels, and a high level of this enzyme was observed in those organs most actively involved in fat metabolism. The possible participation of esterase-6 in fatty acid utilization is discussed. Similarities between esterase-6 of the house mouse and esterase-4 of the rat were demonstrated, further strengthening the view that these enzymes are homologous.Supported by the Deutsche Forschungsgemeinschaft (SFB 46)This is communication no 36 of a research program devoted to the cellular distribution, genetics, and regulation of non-specific esterases     

Linkage of the locus for serum albumin in the house mouse,Mus musculus

An electrophoretic variant for serum albumin in Mus musculus has been used to map the structural gene for this protein to chromosome 5.     

Purification and characterization of esterase 2B of the house mouse, Mus musculus

The N-terminal tryptic peptide of Crithidia oncopelti cytochrome c557 X-Pro-Me3Lys-Ala-Arg in which X represents an unknown N-terminal blocking group was characterized by electrophoresis at pH 2 and by 1H and 13C nuclear magnetic resonance. 1H-NMR spectra of the tryptic peptide suggested that the blocking group X was N,N-dimethylproline although the electrophoretic mobility of the peptide suggested a larger molecular weight. The peptides X-Pro-Me3Lys and X-Pro were generated by treatment of the tryptic peptide with thermolysin and carboxypeptidase and the free blocking group X was prepared by acid hydrolysis. Comparison of the 1H-NMR spectra of these peptides with spectra of synthetic N,N-dimethylproline and N,N-dimethylprolylproline demonstrated that the blocking group was indeed N,N-dimethylproline. The 13C-NMR spectrum of the tryptic peptide was consistent with this conclusion although unambiguous assignments to all resonances could not be obtained because of the small amount of material available. The origin of the dimethylproline blocking group is discussed.     

Of mice and 'convicts': origin of the Australian house mouse, Mus musculus

The house mouse, Mus musculus, is one of the most ubiquitous invasive species worldwide and in Australia is particularly common and widespread, but where it originally came from is still unknown. Here we investigated this origin through a phylogeographic analysis of mitochondrial DNA sequences (D-loop) comparing mouse populations from Australia with those from the likely regional source area in Western Europe. Our results agree with human historical associations, showing a strong link between Australia and the British Isles. This outcome is of intrinsic and applied interest and helps to validate the colonization history of mice as a proxy for human settlement history.     

Ejaculate allocation under varying sperm competition risk in the house mouse, Mus musculus domesticus

A common mechanism through which males can enhance their successin postcopulatory contests over paternity is to inseminate moresperm than their rivals. However, ejaculate production is costlyand the evolution of prudent sperm allocation strategies sensitiveto variation in local levels of sperm competition has now beendemonstrated in diverse taxa, including mammals. Theory predictsan increased sperm allocation in response to an elevated riskof sperm competition, but here we show that male house mice(Mus musculus domesticus) instead ejaculate fewer sperm perejaculate when mating in the presence of a rival male. Thissurprising sperm allocation pattern may be a necessary consequenceof adaptive changes in copulatory behavior, enabling males toachieve more rapid sperm transfer and/or to ejaculate repeatedlyunder risk of sexual competition. The size of a second ejaculatecomponent, the copulatory plug, is unaffected by sperm competitionrisk. Our results highlight how the often complex interplaybetween different reproductive traits can affect the evolutionof sperm competition phenotypes.     

The role of salivary androgen-binding protein in reproductive isolation between two subspecies of house mouse: Mus musculus musculus and Mus musculus domesticus

Previous behavioural studies using inbred lines have suggested that the gene ( Abpa ) for the alpha subunit of salivary androgen-binding protein (ABP) plays a role in prezygotic isolation between house mouse Mus musculus subspecies. We tested this hypothesis in animals from wild allopatric (121 individuals from four samples) and parapatric (320 animals from 15 samples) populations sampled on the Czech–Bavarian transect across the hybrid zone between M. m. domesticus and M. m. musculus . The study did not reveal a consistent statistically significant trend of homosubspecific preferences in individual allopatric and parapatric populations. Nonetheless, the whole pattern of preference was skewed toward homosubspecific preference mostly on the M. m. musculus side of the hybrid zone. The pattern of homosubspecific preferences was stronger for the time spent sniffing than it was for the first choice of the signal (the ratio of homosubspecific vs. heterosubspecific preferences for both sexes was 6 : 2 in allopatric and 21 : 9 in parapatric populations, while the same rates were 4 : 4 and 16 : 14 for the first choice). To the extent that Y-maze tests reflect preference under wild conditions, we suggest that this slight preference may not in itself be sufficient to impede gene flow between the two subspecies and thus act as a reproductive barrier. ABP most probably participates in a complex system of subspecies-specific recognition in the hybrid zone, but the picture is far too complex at this time to allow a conclusive evaluation of the importance of this role.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 349–361.     

Succinate dehydrogenase activity in the developing molar of the hairless mouse Mus musculus

Synopsis Succinate dehydrogenase activity in the odontogenic tissues of the hairless mouse (hr/hr) has been studied from the initiation of the dental lamina through apposition. Enzyme activities were designated as negative, slight, moderate and strong as a function of intensity of the reaction product. Enzyme levels in the odontogenic tissues increased with advancing tooth morphogenesis. Greatest activity was observed in the ameloblastic layer which peaked on the fourth to sixth postnatal days. This cell layer displayed higher enzyme activity than the ectomesenchymally-derived odontoblasts. Succinate dehydrogenase activity appeared to be related to the degree of differentiation and functional competence on the odontogenic tissues of the hairless mouse.     

Structural differences between albumin A and albumin C of the house mouse,Mus musculus

Two albumins, albumin A from C3H mice and albumin C isolated from descendents of the wild mice in which the variant was first uncovered, were found to differ in their electrophoretic properties. Albumin C was shown to bind two more H⁺ ions than albumin A at pH 5.4. Peptide mapping after trypsin digestion revealed that albumin C had three peptides (TP-C1, TP-C2, and TP-C3) which were missing in albumin A. The latter likewise had a peptide (TP-A1) which was not found in albumin C. An amino acid analysis of the variant peptides suggests that TP-A1 had been split into TP-C1 and TP-C2 on digestion with trypsin, because a glutamic acid in TP-A1 was replaced by a lysine. This change would also appropriately alter the electrophoretic properties of albumin C. No obvious counterpart was discovered for TP-C3 of albumin C in albumin A.This work was supported by a grant from the National Research Council of Canada.