Aggressive behaviour in related and unrelated wild house mice (Mus musculus L.)

Aggressive behaviour was observed to be rare in small family groups of confined wild house mice, Mus musculus L. Unrelated mice were attacked when they were introduced to a family group and in their presence intra-family aggressive behaviour increased. When two family groups of mice were allowed to meet there were frequent aggressive encounters between unrelated animals and the two groups remained separate. Resident mice were found to be aggressive towards males and females individually isolated and returned to their own family after 2 or 3 weeks absence but not after 1 week. The possibility is discussed that in wild mice odour discrimination influences the dispersal and build-up of free-living populations.     

Anatomy of musculus levator veli palatini in the 15-week human fetus

The morphology of musculus levator veli palatini in the 15-week fetus was analyzed using 30-micrometer subserial sections. The sample included 26 specimens, of which 9 each were sectioned coronally and sagittally while 8 were sectioned in the transverse plane. At this stage of development m. levator veli palatini takes a general attachment to the precursor of the petrous part of the temporal bone, and, in some cases, auxiliary attachments to the auditory tube complex were also observed. At its origin, the muscle is located anterior to the tube. It then runs medially, passing beneath the auditory tube prior to entering the velum. As it nears the region of the lateral pharyngeal wall, a small fascicle trails posteriorly and inferiorly to the main muscle mass and occasionally runs into the upper margin of m. constrictor pharyngis superior. The levator muscle is more localized within the velum at this stage of development than it has been reported to be in the adult, being confined here to the central third of the soft palate. Most of the fibers of the muscle appear to form a sling within the central 20% of the velum, although some were seen to take attachment to loose connective tissue and the palatine raphe. Upon its entry into the velum, m. levator veli palatini is intersected vertically by bundles of both mm. palatoglossus and palatopharyngeus.     

Allozymic Polymorphism Among 14 Populations of the House Mouse, Mus musculus domesticus, From Greece

Nineteen loci from 239 individuals of the house mouse Mus musculus domesticus (Rodentia, Muridae) were analyzed by means of thin layer electrophoresis. The mice were collected from 14 localities of Greece mainly confined to the area of NW Peloponnese, where a Robertsonian (Rb) system is observed. The individuals were chromosomally characterized by nine diploid numbers, the 2n = 24, 26, 27, 28, 29, 30, 31, 32, and 40. The statistic elaboration revealed that all 14 populations studied were not characterized by cohesive demic structure and high inbreed levels while the gene flow among them has resulted in low levels of genetic differentiation. The resulting values for Neis genetic distance corresponded to distances known for the level of geographical populations of, M. musculus. Wagners cladogram for the phylogenetic relations between the populations studied implied that it is the diploid number, rather than the geographical factor, that characterizes or dominates each population, which mainly influences the phylogenetic relationships.     

Genetic analysis of the hybridization zone between two subspecies Mus musculus domesticus and Mus musculus musculus in Bulgaria

The hybrid zone between the two subspecies of mice Mus musculus domesticus and Mus musculus musculus, which has been studied extensively in Denmark, crosses Europe to the Black Sea through the Alps and the Balkans. Two hundred and seventy-nine animals were captured in 22 localities along a transect across the Balkans. The animals were characterized for seven diagnostic nuclear loci by protein electrophoresis and by restriction pattern analysis of their mitochondrial DNA. The nuclear data show a sharp transition between the two subspecies, most of the variations in allele frequencies (from 0.9 to 0.1) occurring within a 36-km section of the transect. The introgression varies from one locus to the other and is more pronounced, in terms of distance, in M. m. musculus territory. Mitochondrial DNA introgression is important but occurs in one direction only, i.e. from M. m. musculus to M. m. domesticus, while a cytoplasmic transfer from M. m. domesticus to M. m. musculus has been reported. A previous study showed that no Y chromosome introgression occurs. The different behaviour of these three types of markers could be due to the interaction between selection against hybrid genomes and meiotic recombination. Objectively, it would appear that the genes that can introgress are neutral or nearly so and have been separated from deleterious genes they were linked to by recombination. This could explain the differential introgression between autosomal loci. The mitochondrial and Y chromosomes undergo no or very little recombination and each is transmitted as a whole. Their degree of introgression is thus indicative of the intensity of selection resulting from the amount of functional differentiation between the two taxa, which seems to be strong for the Y chromosome and weak for mitochondrial DNA. We propose that the asymmetry of nuclear introgression is due to different population structures. As M. m. musculus is relatively less structured, the rapid spreading of introgressed genes would be favoured. Such a scheme, however, can hardly account for the unidirectionality of the mitochondrial flow, which could be due to sex-dependent behaviour.     

Genetic divergence of Mus musculus musculus and M. m. hortulanus

Genetic divergence between house mouse and gleaner mouse from different regions of Ukraine was estimated by electrophoresis at 26 loci. Four diagnostic loci were established among these species: IDH-1, Est-1,2,4. Genetic distance between species is 0.217, which is in accordance with genetic differences between other species of the genus Mus. The results obtained give evidence that house and gleaner mouse are different species.     

Mitochondrial DNA in the hybrid zone between Mus musculus musculus and Mus musculus domesticus: a comparison of two transects

We studied mtDNA introgression across the contact zone between Mus musculus musculus and M. m. domesticus in two independent transects in the Czech Republic and Bavaria, Germany. A total of 1270 mice from 98 localities in the Czech transect and 456 mice from 41 localities in the Bavarian transect were examined for presence or absence of a Bam HI restriction site in the mt-Nd1 gene. Using this simple mtDNA marker, variants that belonged to the M. m. domesticus lineage (presence of restriction site) could be unequivocally distinguished from those belonging to the M. m. musculus lineage (absence of restriction site). The extent of introgression of mtDNA, three autosomal allozymes and the X chromosome was compared. The introgression of X markers was more limited than was that of the allozymes and mtDNA. In the Czech transect, the centre for the mtDNA cline was shifted about 3.6 km to the west relative to the X chromosome cline, with asymmetric introgression from M. m. musculus to M. m. domesticus . Interestingly, in the Bavarian transect, the centre of the mtDNA cline was shifted about 10.9 km to the east relative to the X chromosome cline, with asymmetric introgression from M. m. domesticus to M. m. musculus, opposite in direction to that observed in the Czech transect.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 363–378.     

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.     

Motivational and Heritable Determinants of Dispersal Latency in Wild Male House Mice (Mus musculus musculus)

Divergence of dispersal regimens has been suggested to be the selective basis for the evolutionary differentiation of agonistic phenotypes found in natural populations of house mice. Dispersal propensity may, therefore, be expected to exhibit heritable variation in wild house mice, ultimately related to motivational differences causing observable differences in agonistic behaviour. To test for heritable components in dispersal propensity in wild house mice, father–offspring regressions of dispersal latencies from residential social groups were determined in standardized seminatural social settings. To evaluate potential motivational causes of phenotypic variation in dispersal behaviour, all test animals (fathers, sons, and daughters) were scored prior to the dispersal experiment in a standardized behavioural test, at 60 d of age. Activities were monitored in a 1 m² square test arena during 10‐min observation periods. Test arenas exhibited four equidistant openings leading to cages containing fresh, own, sibling, or foreign bedding material. The apparatus allowed for scoring anxiety, exploratory activity, and kin preference. Subsequently, test animals were exposed to a resident population in a semi‐natural enclosure providing a dispersal opportunity. Father–son regressions of dispersal latencies were significantly positive, but no significant relationship was found for daughters. Dispersal latency decreased with increasing exploratory activity scores in males, but increased in females. Anxiety as well as kin preferences did not affect dispersal propensity. Hence sex‐linked, motivational components reflect heritable social behaviour variation in male house mice that may ultimately be caused by diverging dispersal regimens.     

Social Status and Resistance to Disease in House Mice (Mus musculus): Status-related Modulation of Hormonal Responses in Relation to Immunity Costs in Different Social and Physical Environments

Unrelated and previously unfamiliar male mice were maintained in groups of six tor different periods and at different ambient temperatures. High- and low-ranking males differed in hormone-related resistance to a subsequent experimental infection with the blood protozoan Babesia microti and there were rank differences in the apparent modulation of immunodepressive hormones relative to an individual's internal, social and physical environment. Resistance to B. microti was influenced by serum concentrations of corticosterone and testosterone. Associations between aggressiveness and measures of immunocompetence and resistance were related to corticosterone concentration, but only among low rankers. Effects of testosterone on resistance were confined to high rankers but were not associated with aggressiveness, although high rankers maintained greater aggressiveness than low rankers in all experimental treatments. The effects of group duration and temperature on resistance can be interpreted in terms of changing hormone and antibody levels in relation to metabolic stress. The results emphasize the importance of interactions between underlying physiological changes in relationships between behaviour, immune function and disease.     

Cryptosporidium tyzzeri and Cryptosporidium muris originated from wild West-European house mice (Mus musculus domesticus) and East-European house mice (Mus musculus musculus) are non-infectious for pigs

Three and 8 week old pigs were inoculated with Cryptosporidium muris HZ206 (Mus musculus musculus isolate), Cryptosporidium tyzerri CR2090 (M. m. musculus isolate) or C. tyzzeri CR4293 (isolate from a hybrid between Mus musculus domesticus and M. m. musculus) at a dose of 1 × 10(7) oocysts per animal. Inoculated pigs showed no detectable infection and no clinical symptoms of cryptosporidiosis during 30 days post infection (DPI), and no macroscopic changes were detected in the digestive tract following necropsy. Developmental stages were not detected in gastrointestinal tract tissue by histology or PCR throughout the duration of the experiment. The infectivity of isolates was verified on SCID mice, in which oocysts shedding started from 4 to 8 DPI. Based on our findings, it can be concluded that pigs are not susceptible to C. muris or C. tyzzeri infection.     

Nonspecific esterases of Mus musculus

Seventeen genes controlling the expression of carboxylic ester hydrolases, commonly known as esterases, have been identified in the mouse Mus musculus. Seven esterase loci are found on chromosome 8, where two clusters of esterase loci occur. It seems probable that the genes within these clusters have arisen from a common ancestral gene by tandem duplication. Close linkage of esterase genes is also found in the rat, rabbit, and prairie vole. Some mouse esterases appear to be homologous with certain human esterases. The function of these nonspecific enzymes is still unknown.     

Polymorphism in hybrid male sterility in wild-derived Mus musculus musculus strains on proximal chromosome 17

The hybrid sterility-1 (Hst1) locus at Chr 17 causes male sterility in crosses between the house mouse subspecies Mus musculus domesticus (Mmd) and M. m. musculus (Mmm). This locus has been defined by its polymorphic variants in two laboratory strains (Mmd genome) when mated to PWD/Ph mice (Mmm genome): C57BL/10 (carrying the sterile allele) and C3H (fertile allele). The occurrence of sterile and/or fertile (wild Mmm × C57BL)F₁ males is evidence that polymorphism for this trait also exists in natural populations of Mmm; however, the nature of this polymorphism remains unclear. Therefore, we derived two wild-origin Mmm strains, STUS and STUF, that produce sterile and fertile males, respectively, in crosses with C57BL mice. To determine the genetic basis underlying male fertility, the (STUS × STUF)F₁ females were mated to C57BL/10 J males. About one-third of resulting hybrid males (33.8%) had a significantly smaller epididymis and testes than parental animals and lacked spermatozoa due to meiotic arrest. A further one-fifth of males (20.3%) also had anomalous reproductive traits but produced some spermatozoa. The remaining fertile males (45.9%) displayed no deviation from values found in parental individuals. QTL analysis of the progeny revealed strong associations of male fitness components with the proximal end of Chr 17, and a significant effect of the central section of Chr X on testes mass. The data suggest that genetic incompatibilities associated with male sterility have evolved independently at the proximal end of Chr 17 and are polymorphic within both Mmd and Mmm genomes.     

The Mus musculus domesticus Tdy allele acts later than the Mus musculus musculus Tdy allele: a basis for XY sex-reversal in C57BL/6-YPOS mice.

Consomic C57BL/6 males, carrying either the Mus musculus musculus-derived C57BL/6 Y chromosome or the Mus musculus domesticus-derived Poschiavinus Y chromosome, were outcrossed to females of the inbred strains C3H/Bi and CXBH/By and to females of the random bred strain MF1/Ola. In a study at 12.5 days post coitum, gonads of XYC57 and XYPOS fetuses were assessed for the presence of testicular cords. It was found that XYPOS fetuses had a later onset of testicular development than XYC57 fetuses. Limb development, which was monitored as a measure of overall development, was unaffected by the strain of Y present. These data were supported by a longitudinal study in which the increased growth rate of the testes relative to undifferentiated gonads, was also shown to be delayed in XYPOS fetuses. The extent of the delay was estimated to be approximately 14 h. It is concluded that this delay in the onset of testicular differentiation must be caused by differences between the two Y-chromosome types, most probably allelic differences in the testis determinant Tdy.     

Allelic profile at 37 biochemical loci of two inbred strains of the house mouse derived from wild Mus musculus musculus

Two newly established inbred strains derived from Mus musculus musculus, designated PWD/Ph (F29) and PWK/Ph (F33), were examined for their alleles at 37 biochemical loci located on 12 different chromosomes. The allelic pattern showed characteristic differences from those observed in common inbred strains. The genetic distance D between PWK/Ph and PWD/Ph was 0.027, whereas the corresponding values for the genetic distances between PWK/Ph and C57BL/6J, DBA/2J, BALB/cJ and SWR/J were 0.777, 0.721, 0.721 and 0.838 respectively. New allozymes are described as being controlled by the loci Es-23, Pre-2 and Tam-1. The genetic relationship to M.m.molossinus is indicated by identical alleles at six other loci (Es-2, Es-9, Es-10, Es-11, Es-18 and Es-22).     

Immunologic Control of Mus musculus Papillomavirus Type 1

Persistent papillomas developed in ~10% of out-bred immune-competent SKH-1 mice following MusPV1 challenge of their tail, and in a similar fraction the papillomas were transient, suggesting potential as a model. However, papillomas only occurred in BALB/c or C57BL/6 mice depleted of T cells with anti-CD3 antibody, and they completely regressed within 8 weeks after depletion was stopped. Neither CD4+ nor CD8+ T cell depletion alone in BALB/c or C57BL/6 mice was sufficient to permit visible papilloma formation. However, low levels of MusPV1 were sporadically detected by either genomic DNA-specific PCR analysis of local skin swabs or in situ hybridization of the challenge site with an E6/E7 probe. After switching to CD3+ T cell depletion, papillomas appeared upon 14/15 of mice that had been CD4+ T cell depleted throughout the challenge phase, 1/15 of CD8+ T cell depleted mice, and none in mice without any prior T cell depletion. Both control animals and those depleted with CD8-specific antibody generated MusPV1 L1 capsid-specific antibodies, but not those depleted with CD4-specific antibody prior to T cell depletion with CD3 antibody. Thus, normal BALB/c or C57BL/6 mice eliminate the challenge dose, whereas infection is suppressed but not completely cleared if their CD4 or CD8 T cells are depleted, and recrudescence of MusPV1 is much greater in the former following treatment with CD3 antibody, possibly reflecting their failure to generate capsid antibody. Systemic vaccination of C57BL/6 mice with DNA vectors expressing MusPV1 E6 or E7 fused to calreticulin elicits potent CD8 T cell responses and these immunodominant CD8 T cell epitopes were mapped. Adoptive transfer of a MusPV1 E6-specific CD8+ T cell line controlled established MusPV1 infection and papilloma in RAG1-knockout mice. These findings suggest the potential of immunotherapy for HPV-related disease and the importance of host immunogenetics in the outcome of infection.     

年龄对小家鼠筑巢的影响

为研究不同年龄组小家鼠筑巢能力的差异,分别采用24-h等级法和连续4d巢材获取重量法,对幼年组、亚成年组、成年组小家鼠筑巢能力进行了测定。结果表明:1)小家鼠在亚成年期已具备较强的筑巢能力;2)成年组与亚成年组小家鼠能够快速完成筑巢,24h即可筑成稳定的杯状巢,而幼年组未能筑成稳定巢;3)小家鼠雄性与雌性筑巢能力相当;4)连续4d巢材获取重量表现为成年组>亚成年组,这与两组间身体大小有关,而4d后两组间筑巢等级无显著差异。研究结果提示,不同年龄组的小家鼠均有较强的筑巢需求,筑巢能力基本形成于亚成年期。     

Recombinant expression of Mus musculus myoglobin

The cDNA encoding for Mus musculus myoglobin (Mb) was amplified using standard RT-PCR techniques and cloned in an appropriate bacterial expression vector. For the first time, mouse Mb was recombinantly expressed in Escherichia coli cells, BL21(DE3), and purified in sufficient amounts to carry out a preliminary characterization. As shown by mass spectrometry, the protein is found in complex with glutathione, which binds the Cys residue in the topological position E9, in the proximity of the heme group. In recombinant murine Mb, azide affinities are only slightly dependent on the Cys(E9) oxidation state. This suggests that Cys(E9) does not provide a relevant contribution for the stabilization of ligands bound to the heme iron atom. Recombinant expression of M. musculus Mb might have an important role in order to investigate the eventual involvement of Cys(E9) in the new physiological roles proposed for Mb.     

Norwegian house mice (Mus musculus musculus/domesticus): distributions, routes of colonization and patterns of hybridization

We investigated the distributions and routes of colonization of two commensal subspecies of house mouse in Norway: Mus musculus domesticus and M. m. musculus. Five nuclear markers (Abpa, D11 cenB2, Btk, SMCY and Zfy2) and a morphological feature (tail length) were used to differentiate the two subspecies and assess their distributions, and mitochondrial (mt) D‐loop sequences helped to elucidate their colonization history. M. m. domesticus is the more widespread of the two subspecies, occupying the western and southern coast of Norway, while M. m. musculus is found along Norway’s southeastern coast and east from there to Sweden. Two sections of the hybrid zone between the two subspecies were localized in Norway. However, hybrid forms also occur well away from that hybrid zone, the most prevalent of which are mice with a M. m. musculus‐type Y chromosome and an otherwise M. m. domesticus genome. MtDNA D‐loop sequences of the mice revealed a complex phylogeography within M. m. domesticus, reflecting passive human transport to Norway, probably during the Viking period. M. m. musculus may have colonized earlier. If so, that leaves open the possibility that M. m. domesticus replaced M. m. musculus from much of Norway, with the widely distributed hybrids a relict of this process. Overall, the effects of hybridization are evident in house mice throughout Norway.     

Characterization of two electrophoretic lactate dehydrogenase-A mutants inMus musculus

Two lactate dehydrogenase (LDH) mutations were recovered independently among offspring of ethylnitrosourea-treated male mice by screening for alterations of isoelectric focusing pattern in liver homogenates. Investigations of physicochemical and kinetic properties of the mutant enzymes indicated that the mutant traits resulted from point mutations at theLdh-1 structural locus. Therefore, the new alleles were designatedLdh-1 ^a-m5Neu andLdh-1 ^a-m6Neu, respectively. Both mutant alleles code for proteins which exhibit an altered stability to heat, in addition to changes in isolectric focusing pattern and a reduction in anodal electrophoretic mobility. While LDH-A^a-m5Neu proteins are markedly less heat stable, LDH-A^a-m6Neu proteins are more heat stable than the wild-type enzyme. Furthermore, a small elevation ofK _m for pyruvate, a slightly reduced inhibition by high pyruvate concentrations, and a slight acidic shift of the pH activity profile distinguish LDH-A^a-m6Neu from both wild-type and LDH-A^a-m5Neu enzymes. Significant alterations of LDH activity were detected in some tissues from LDH-A^a-m5Neu individuals but not in those from LDH-A^a-m6Neu animals. Erythrocytes and blood of LDH-A^a-m5Neu mutants revealed activity levels which were reduced by approximately 6 and 13% compared with those of wild types in heterozygous and homozygous individuals, respectively. In addition, an elevation of approximately 6% in LDH activity was found in skeletal muscle in homozygous mutants. Consistent with the unaltered or only slightly altered LDH activity in tissues, the genetic as well as the physiological characterization yielded no easily detectable effects from either mutation on metabolism or fitness of the affected individuals.This research was supported in part by Contract BI6-156-D from the Commission of the European Communities.