Genetic individuality of intracisternal A-particles of Mus musculus.

The nucleic acid sequence relationship between mouse intracisternal type A-particles and type C and B viruses was examined by reciprocal complementary DNA-RNA hybridization; complementary DNAs prepared from the RNAs of intracisternal A-particles were hybridized with high-molecular-weight RNAs from a variety of murine tumor viruses, and complementary DNAs representing a variety of RNA tumor virus genomes were hybridized with the high-molecular-weight RNAs from A-particles. The criterion for homology between two types of virus was that the heterologous hybridization reaction occurs over the same RNA concentration range as the homologous reacton. The results of these hybridizations indicate that there are no major sequence homologies between the RNA of intracisternal A-particles and the RNA of representative members of type B and C viruses of Mus musculus.     

Two types of mouse (Mus musculus domesticus) Y chromosomes in Quebec.

A Y chromosomal repetitive sequence identified two types of Y chromosomes in mice (Mus musculus domesticus) caught near Ste. Anne de Bellevue, Quebec. One type is apparently identical to the Y chromosome found in Maryland, Delaware, and California, whereas the other type is similar, but not identical, to the Y chromosome present in M.m. poschiavinus, an Alpine race of M.m. domesticus. These findings suggest that the domesticus Y chromosome is highly polymorphic and thus useful for elucidating the relationships among American and European house mouse populations.     

Expression of glucose phosphate isomerase in interspecific hybrid (Mus musculus x Mus caroli) mouse embryos.

Hybrid Mus musculus x Mus caroli embryos were produced by inseminating M. musculus (C57BL/OlaWs) females with M. caroli sperm. Control M. caroli embryos developed more rapidly than did control M. musculus embryos and implanted approximately 1 day earlier. At 1 1/2 days, both the hybrid embryos and those of the maternal species (M. musculus) had cleaved to the 2-cell stage. By 2 1/2 days some of the hybrids were retarded compared to M. musculus, and by 3 1/2 days most were lagging behind. This is consistent with the idea that the rate of development of hybrid embryos declines once it becomes dependent on embryo-coded gene products. We have used this difference in rate of preimplantation development, between hybrid and M. musculus embryos, to try to determine whether the activation of embryonic Gpi-1s genes, that encode glucose phosphate isomerase (GPI-1), is age-related or stage-related. In control M. musculus embryos (both mated and Al groups), the GPI-1AB and GPI-1A allozyme, indicative of paternal gene expression, were detected in 7 of 9 samples of 3 1/2-day compacted morula stage embryos and were seen in all 19 samples of 3 1/2-day blastocysts. In hybrid embryos, these allozymes were detected 1 day later. They were not detected in any 3 1/2-day samples (12 samples of compacted morulae) but were consistently detected at 4 1/2 days (4 samples of blastocysts and 2 samples of uncompacted morulae). Our interpretation of the results is that gene activation in hybrid embryos is stage-specific, rather than age-specific, and probably begins around the 8-cell stage, with detectable levels of enzyme accumulating later. Analysis of GPI-1 electrophoresis indicated that both the paternal (M. caroli) and maternal (M. musculus) Gpi-1s alleles were equally expressed in hybrid embryos and that the paternally derived allele was not activated before the maternally derived allele.     

The pancreatic islet system of the mouse (Mus musculus)

Summary The pancreatic islet in the mouse has a highly complex and heterogeneous structure. It contains Aa, Ab, Ac, B, C, D, E, and F cells. The classification of cell types is primarily based on the shape, size and electron opacity of secretory granules and on the spatial relationship of the granules to their unit membranes. Morphological evidence is supported by a statistical analysis of the size distribution of granules and of their membranes. Experimental immunization of mice with insulin, provides additional data to support the existence of eight different cell types in the islet of the normal animal and reveales marked immunological stimulation of B cells, secondary stimulation of Aa, D and F cells, atrophy of Ac cells and hyperplasia of C cells. It is proposed that corresponding cell types exist in other mammals and man. The experimental insulin immunization process appears to perform an immunofunctional analysis of the islet, and suggests that in mice the Aa, D and F cells might be involved in cell energy supply. Lipocaic and some pancreatic factors with insulin-like activity (NSILA) will likely find their morphological equivalents. It is proposed that chemical solubility techniques represent the most promising avenues of approach to the isolation of secretory products from the endocrine pancreas, and that the assay of these extracts should primarily be conducted at the cell level.Dedicated to Prof. Dr. med. W. Masshoff on his 60th birthday.The author is indebted to Dr. med. H. J. Stolpmann for guidance in applying the techniques of electron microscopy and wishes to express his special appreciation to Mrs. Marjanne Hinz for her valuable assistance in completing different aspects of this work and for her competent technical aid.     

Reproduction of the House mouse (Mus musculus) in farm buildings

Live and kill traps were used to remove House mice living in granaries, mixed-food stores, dairy units and ancillary stores on farms. Structural weaknesses were common to all buildings. Cavities in walls, in particular, provided favourable living and nesting quarters for mice and were rapidly exploited. The body-weight structure and reproductive traits of the populations in the different habitats were compared. The onset of maturity, in both sexes, was closely related to body-weight increase in the 10 to 14 g range. Breeding, unlike that in most out-door populations in temperate climates, continued throughout the year. Ancillary buildings holding limited food supported small reservoir populations. Mice inhabiting dairy units containing pelleted cattle feed tended to be heavier than those sampled elsewhere and females in the units produced the largest litters. Reproductive performance on farms was intermediate between that of mice occupying urban buildings and corn ricks. There was evidence that environmental and behavioural factors were operating to limit increase in numbers in the dairy units.     

Spontaneous thyroid follicular adenoma in a laboratory mouse (Mus musculus)

Spontaneous thyroid micro-follicular adenoma was found in an 18-month-old nursing Swiss albino mouse. The lesion was first noted as a tiny bulge at the base of the neck. The tumor was solid, and within two months, had grown such an enormous size that movement, feeding and suckling of the litter were greatly hampered. The litter of seven mice later died due to improper nursing while their mother remained generally unaffected by the mass.     

Genetical variation in three Pacific House mouse (Mus musculus) populations

Studies of allozymic variation at 36 loci in samples of House mouse ( Mus musculus ) populations collected from the island of Hawaii and two islets in the Enewetak Atoll, Marshall Islands are reported. All three populations carried a great deal of inherited variation: the Hawaiian sample had a mean heterozygosity of 16.6% per locus, which is the highest value so far found for a mouse population. The mean heterozygosities for the two atoll populations were 11.4% and 10.9%.
There were no changes in either heterozygosity or allozyme frequencies with age. In this respect, these populations from the tropical Pacific differed from populations living in cold temperate regions where natural selection has been shown to affect allele frequencies in different ways at different stages of the life cycle.     

The skeletal correlates of behavioral modification in the laboratory mouse (Mus musculus)

The effects of behavioral modification on the skeletal morphology of the laboratory mouse (Mus musculus) are investigated. Climibing, with increrased prehensile use of the foot, is found to bring about significant changes in metatarsal and long bone morphology. Differences in metatarsal robusticity related to weight-bearing differences associated with different locomotor patterns are reported for a natural history setting for Peromyscus.     

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     

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.