Influenza Infection Neutralizes the Attractiveness of Male Odour to Female Mice (Mus musculus)

This study aimed to determine if female house mice, Mus musculus domesticus, are able to assess a male's infection status from odour cues. We collected urine from male mice before, during, and after they were experimentally infected with influenza, a respiratory virus. Females spent more time investigating urine collected from males while they were uninfected than when they were infected. Also 70 % of females released into a large enclosure preferred to nest in boxes containing urine collected from uninfected rather than infected males. This is the first evidence that mice can discriminate virally infected individuals through chemical signals and the first evidence that infection causes odour changes in the urine. To determine if the odour of infected males is repulsive, we presented females with urine samples and neutral water blanks. Normal urine collected from uninfected males was more attractive, whereas urine collected during infection was as attractive as water. This indicates that rather than being aversive, influenza infection abolishes the attractiveness of a male's odour. A similar effect also occurs when male mice are infected with coccidian gut parasites (Kavaliers & Colwell 1995, Proc. R. Soc. Lond. 261B, 31–35). One proximate reason for the neutralization of the attractiveness of a male's odour may be a decrease in serum androgen concentrations during infection.     

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.     

Mice (Mus musculus) lacking a vomeronasal organ can discriminate MHC-determined odortypes

Major histocompatibility complex (MHC) genes in mammals (H-2 in mice) play a major role in regulating immune function. They also bestow individuality in the form of a chemical signature or odortype. At present, the respective contributions of the olfactory epithelium and the vomeronasal organ (VNO) in the recognition of individual odortypes are not well defined. We examined a possible role for the VNO in the recognition of MHC odortypes in mice by first removing the organ (VNX) and then training the mice to distinguish the odors of two congenic strains of mice that differed only in their MHC type. C57BL/6J mice (bb at H-2) and C57BL/6J-H-2(k) (kk at H-2) provided urine for sensory testing. Eight VNX and six sham-operated mice were trained to make the discrimination. Neither the number of training trials-to-criterion nor the rate of learning differed significantly for VNX and sham-operated mice. We conclude that the VNO is not necessary for learning to discriminate between MHC odortypes.     

Oxytocin and Social Preference in Female House Mice (Mus musculus domesticus)

In social species, same‐sex individuals may form social bonds behaviourally expressed as individual preferences, resulting in fitness benefits such as increased offspring survival, longevity and group cohesion. As a result of individual preferences, female house mice (Mus musculus domesticus) form social affiliations while communally nursing and may do so with kin or non‐kin. However, the mechanisms behind the formation of such preferences are unknown. Oxytocin has been linked to a range of social behaviours including bond facilitation, social memory and parental care. Here, we experimentally increased oxytocin in pairs of unfamiliar, unrelated females and predicted that females with elevated oxytocin would demonstrate increased affiliative behaviours compared against a control. Subsequently, we tested for the formation of a social preference, using a preference test with the previous partner and a new unfamiliar female. Our results indicated no significant effect of treatment on positive and negative behaviours between females during the three initial cohabitation days. In both treatments, females demonstrated increased socio‐positive behaviours and cohabitation time with their partner and decreased socio‐negative behaviours and latency to meet, over the 3‐d period. During the partner preference test, control but not oxytocin females demonstrated a significant preference for their cohabitation partner, and oxytocin females spent similar amounts of time with both stimulus females. Therefore, increasing peripheral oxytocin appears not to be involved in the facilitation of initial encounters with a stranger but may hinder the formation of a preference for this new partner.     

扬子鳄幼鳄出壳前后的鸣声特征比较

成年扬子鳄(Alligator sinensis)的声信号已经有过深入的研究,然而其声音的个体发育,特别是幼鳄出壳前后鸣声的时空特征至今还不为人所知。为了解扬子鳄声音的发育过程,记录和分析了21只扬子鳄幼鳄的260个叫声,结果表明,幼鳄出壳前后的鸣声具有相似的特征,即开始向上的频率调节和较长的向下的频率调节。出壳前和出壳后的两组叫声均包括持续叠加的多组谐波,并且绝大多数的鸣声都是在第3谐波显示了最强的能量。分析了出壳前后鸣声的9个参数,即总时长、向上调频的时长、向下调频的时长、基频的起始频率、最高频率、结束频率、向上调频的倾斜度、向下调频的倾斜度、主频。除了向上调频的时长,出壳前后鸣声的其他时长参数均没有表现出显著差异。与之相反的是,出壳前后鸣声的频谱参数,特别是基频的最高频率和主频均表现出显著差异(P0.05)。出壳前鸣声基频的最高频率为(573±103)Hz,出壳后的声音最高频率(460±52)Hz,出壳前比出壳后高113 Hz;出壳前的声音主频(1 359±229)Hz,出壳后的声音主频(1 123±216)Hz,前者比后者高236 Hz。幼鳄发出主频较高的鸣叫有利于吸引附近母鳄的注意同时避免天敌的捕食。     

Olfactory Mechanisms Affording Protection from Attack to Juvenile Mice (Mus musculus L.)

In the course of their evolution domestic animals were selected by man not only for physical characteristics and physiological properties, but also for certain behaviour patterns. This permits us to trace the development of new behaviours during historically documented time. In three pigeon breeds — Swing Pouter, Birmingham Roller, Rhine Ringbeater — the development and evolution of breed-specific flight manoevers with courtship function under the influence of human selection was examined, and their course reconstructed. Behaviour patterns which in wild animals would have been eliminated through natural selection were able to develop under human protection and selection.     

转Bar基因稻谷对小鼠(Mus musculus)肠道菌群的作用研究

选取6周龄、雌雄各半、体重18~22 g的SPF级昆明小鼠(Mus musculus)100只,随机分成5组,每组4个重复,每个重复5只小鼠。分别用含量为40%和60%的转Bar基因稻谷Bar68-1和非转基因稻谷D68日粮喂养小鼠,亲代小鼠饲养180 d后开始繁殖子一代(F1),每代小鼠饲养180 d。在180 d后分别从亲代和子一代每组随机抽取5只小鼠,提取肠道内容物基因组DNA,利用细菌通用引物对细菌16S r DNA的V3区序列进行PCR扩增,并将扩增产物用变性梯度凝胶电泳(denaturing gradient gel electrophoresis DGGE)。研究显示,各组小鼠肠道菌群相似性系数无显著差异(P0.05);肠道主要优势菌群相同。结果表明,转Bar基因稻谷对小鼠肠道菌群的作用不明显。     

Extraintestinal Development of Caryospora simplex (Apicomplexa: Eimeriidae) in Experimentally Infected Mice,Mus musculus1

Developmental stages of Caryospora simplex were found in connective tissue of the cheek, tongue, and nose of Swiss-Webster and C57 BL/6 mice (Mus musculus) from 8 through 70 days after oral inoculation with 50,000 or 250,000 oocysts, or 60,000 free sporocysts of the same species obtained from an Ottoman viper, Vipera xanthina xanthina. The earliest developmental stages were seen on day 8 post-inoculation (PI) and consisted of two types of meronts and gamonts (undifferentiated sexual stages). Gamonts, microgametocytes, macrogametes, and unsporulated oocysts were found on days 10 and 12 PI. Fully sporulated, thin-walled oocysts containing eight sporozoites surrounded by a thin sporocyst membrane were first seen 12 days PI. Monozoic cysts (caryocysts) were first seen 12 days PI and appeared fully viable throughout the duration of the study, 70 days PI. Four mice injected intra-peritoneally with 150,000 free sporozoites and killed 12 days PI contained unsporulated and sporulated oocysts in connective tissues of the cheek, tongue, and nose, suggesting that sporozoites may be carried to the site of infection via the lymphatic/circulatory system. Four cotton rats, Sigmodon hispidus, inoculated orally with 250,000 oocysts all had unsporulated and sporulated oocysts of C. simplex in connective tissue of the cheek, tongue, and nose when killed on day 12 PI, indicating extraintestinal development in the secondary host is not species specific. This is the first report of a heteroxenous coccidium with both asexual and sexual development in the primary (predator) and secondary (prey) hosts.     

Infectious Diseases in Wild Mice (Mus musculus) Collected on and around the University of Pennsylvania (Philadelphia) Campus

Laboratory mice serve as important models in biomedical research. Monitoring these animals for infections and infestations and excluding causative agents requires extensive resources. Despite advancements in detection and exclusion over the last several years, these activities remain challenging for many institutions. The infections and infestations present in laboratory mouse colonies are well documented, but their mode of introduction is not always known. One possibility is that wild rodents living near vivaria somehow transmit infections to and between the colonies. This study was undertaken to determine what infectious agents the wild mice on the University of Pennsylvania (Philadelphia) campus were carrying. Wild mice were trapped and evaluated for parasites, viruses, and selected bacteria by using histopathology, serology, and PCR-based assays. Results were compared with known infectious agents historically circulating in the vivaria housing mice on campus and were generally different. Although the ectoparasitic burdens found on the 2 populations were similar, the wild mice had a much lower incidence of endoparasites (most notably pinworms). The seroprevalence of some viral infections was also different, with a low prevalence of mouse hepatitis virus among wild mice. Wild mice had a high prevalence of murine cytomegalovirus, an agent now thought to be confined to wild mouse populations. Helicobacter DNA was amplified from more than 90% of the wild mice (59% positive for H. hepaticus). Given the results of this study, we conclude that wild mice likely are not a source of infection for many of the agents that are detected in laboratory mouse colonies at the University of Pennsylvania.Abbreviations: EDIM, epizootic diarrhea of infant mice; MAV, mouse adenovirus; MCMV, murine cytomegalovirus; MFIA, multiplex fluorescent immunoassay; MHV, mouse hepatitis virus; MNV, murine norovirus; MPV, mouse parvovirus; MVM, minute virus of mice; TMEV, Theiler mouse encephalomyelitis virusLaboratory mice constitute the most popular animal models used in biomedical research today. Like all animals, even mice housed in so-called ‘barrier’ facilities are subject to infection. The infectious agents and organisms present in laboratory mouse colonies on the University of Pennsylvania campus are known and documented by the University Laboratory Animal Resources Diagnostic Services Unit. Sentinel mice that are housed on soiled bedding from resident mouse cages are screened onsite at 3 quarterly intervals for fur mites and pinworms and for a panel of viral infections: mouse hepatitis virus (MHV); epizootic diarrhea of infant mice (EDIM) virus; minute virus of mice (MVM); mouse parvovirus (MPV); Theiler mouse encephalomyelitis virus (TMEV); and Sendai virus. Comprehensive bacteriology and parasitology assessments are performed on all sentinels once yearly during the fourth quarter. In addition, these sentinels are screened serologically for 18 viral infections, Mycoplasma pulmonis, cilia-associated respiratory bacillus, and Encephalitozoon cuniculi and by PCR for Helicobacter spp. and M. pulmonis. Mesenteric lymph nodes from sentinels monitoring barrier-maintained colonies are also screened once yearly by PCR for MPV. In addition, University Laboratory Animal Resources maintains a quarantine facility for rodents received from nonapproved sources (sources other than selected commercial breeding facilities). Mice entering the quarantine facility are housed in semirigid isolators, and contact sentinels are tested for all of the agents included in the fourth quarter comprehensive health assessment described, including PCR for MPV.Wild mice (Mus musculus) could serve as a source of infection or infestation in laboratory mouse colonies, although little is known about the prevalence of infectious diseases in wild mouse populations in Philadelphia. However, we have surveyed wild mouse populations in other geographic areas.^1,9 Significant seroprevalence of MHV, EDIM, murine cytomegalovirus (MCMV), parvovirus, and thymic virus (murid herpesvirus 3), in addition to the presence of many types of parasites and bacteria including Myocoptes spp., Myobia spp., Radfordia spp., Spironucleus spp., Giardia spp., Pasteurella pneumotropica, Pseudomonas spp., and Leptospira spp. were found in wild populations of mice from farms in southeastern Connecticut.¹ Studies of wild mouse (Mus domesticus) populations in the cereal-growing region of southeastern Australia revealed a high serologic prevalence of MHV, EDIM, and MCMV, as well as significant seroprevalence of mouse adenovirus (MAV), MPV, and reovirus type 3.⁹The goal of the current study was to expand preliminary data obtained from wild mice trapped in the University City district of Philadelphia in 2005 (which are included with the current results from a 2007 survey). These data document the prevalence of various infectious agents and parasites commonly found in populations of wild mice on the University of Pennsylvania campus in Philadelphia and are discussed in the context of infectious disease outbreaks in campus vivaria over the past 5 y.     

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.     

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.     

Effects of Different Types of Bedding Materials on Behavioral Development in Laboratory CD1 Mice (Mus musculus)

Male and female mice were housed in cages, containing different types of bedding materials (wood flakes or pulp chips), from 4 weeks of age in the F₀ generation to 11 weeks of age in the F₁ generation; selected reproductive and neurobehavioral parameters were measured in the F₁ generation. There were no adverse effects of bedding materials on litter size, litter weight, or sex ratios at the time of birth. With regard to behavioral development parameters, bedding materials did not influence any variables (p > 0.05) in both sexes. Regarding exploratory behavior in the F₁ generation, number of defecations significantly varied (p = 0.0203) with bedding materials in males at 3 weeks of age. The number of horizontal activities also significantly varied (p = 0.0342) with bedding materials in males at 8 weeks of age. Multiple‐T water maze performance data indicated that the time required was significantly shortened across trials in pulp chips group than wood flakes group in males (p = 0.0211). Moreover, all spontaneous behavior variables in males significantly varied with bedding materials, particularly the average time of movement was significantly different (p = 0.0037) in distance between parallel lines of types of bedding materials in the F₁ generation. The present study shows that bedding materials influence the neurobehavioral development in mice     

Impact of Social Ties on Dispersal,Reproduction and Dominance in Feral House Mice (Mus musculus domesticus)

The existence of a relationship between the social ties an individual has to other family members and its further role within the family was tested in feral house mice (Mus musculus domesticus), according to the ‘Social cohesions hypothesis’. It is predicted by the hypothesis that individuals not forming strong social ties are the first who emigrate. House mice were studied using a population cage system that allowed continuous observation of individually marked animals. Data on time staying with other animals (social ties), aggressive interactions, body weight, reproduction, and emigration were collected daily. The results may be summarized as follows:

• 1 Male emigrants were less integrated in cohorts of male littermates compared with their brothers of the same age. These male cohorts appeared to protect single males from attacks by the dominant male. No difference could be observed in social ties to other family members.
• 2 After weaning, there was no difference in social ties of male and female offspring. However, after sexual maturation social ties of males decreased significantly while those of females remained almost constant.
• 3 Female emigrants showed the same intensity of social ties as their resident sisters.
• 4 No difference could be found between social ties of females becoming pregnant and their nonreproductive sisters of the same age. Reproduction or reproductive suppression could not be explained by having more or less contact with other reproductive females.
• 5 Dominant males spent least of all time with other family members.

The social cohesions hypothesis has to be rejected in analysing proximate causes of emigration. In house mice, male emigration was caused by aggression of the dominant male in competition for the top rank within the group. This was enhanced by a lower integration in the group of same-aged brothers but is not related to a lack of integration into the family.