Experimental maduromycosis in the laboratory mouse

Summary 1. A 0.5 ml inoculum containing 1.4×10⁴ spores and/or mycelial fragments ofAllescheria boydii when injected intraperitoneally, did not cause death in 18–20 g female Swiss mice in 18 days.2. Focal, pin-point lesions developed in the liver and spleen of mice injected with the stock suspension and the 1:10 dilution of it (2.8×10⁴ and 2.8×10³ infective units ofA. boydii per ml, respectively); no lesions developed from the 1:100 dilution of the original suspension.3.Allescheria boydii was recovered from the livers and spleens of all mice, as well as from the peritoneal exudate of one mouse injected with the stock suspension ofA. boydii; the fungus was not isolated from heart's blood.4. Inability to cause death by the intraperitoneal injection ofA. boydii inocula might be attributed to the natural defense mechanisms in the mice or to the excessive dilution of the inoculum; it is improbable that any genetically controlled resistance to allescheriosis exists in the mice used in this study.Paper no. 664, Department of Botany and Plant Pathology, Ohio State University, 1735 Neil Avenue, Columbus 10, Ohio.This is the report of research done by the junior authors with the guidance of the senior author during a course in medical mycology in this department.     

Growth of the laboratory mouse

Summary Body weights and tail lengths were observed every 3 days from birth to 60 days of age and every 6 days from 60 to 96 days in four lines of mice: C57BL/6J, an inbred; J, a synthetic outbred; GR, Goodale large body size line; and FR, Falconer large body size line. Mean 96-day body weights for lines C57BL, J, GR and FR were 25.4, 29.7, 48.8 and 49.1 gm for males, and 19.9, 23.8, 38.5 and 38.2 gm for females, respectively. Lines GR and FR gave identical body weights at all ages studied. Both of these lines had previously plateaued in response to selection for large body size. The variability in body weight was smallest for lines C57BL and J, intermediate for FR and highest for GR. The pattern of variance over time was very similar in all lines and both sexes, showing a minimum at birth and a maximum at age of inflection. Growth in tail length of the four lines showed similar between line differences except that length in GR was greater than in FR. Age at vaginal opening in females coincided closely with age of inflection in body weight growth. Age at point of inflection did not differ between lines but appeared to occur somewhat earlier in females than in males.

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Zusammenfassung Vier Linien von Laboratoriumsmäusen: der Inzuchtstamm C57BL/6J, der Kreuzungsstamm J, eine vonGoodale auf Körpergröße selektierte Linie GR und die vonFalconer auf Körpergröße ausgelesene Linie FR, wurden auf Körpergewicht und Schwanzlänge untersucht, und zwar von der Geburt bis zum 60. Lebenstage in 3 tägigem Abstand, von 60. bis 96. Lebenstage in 6tägigem Abstand. Am 96. Lebenstag betrugen die Durchschnittsgewichte für die 4 Linien 25,4; 29,7; 48,8 und 49,1 g für Männchen und 19,9; 23,8; 38,5 und 38,2 g für Weibchen. Die Linien GR und FR zeigten in allen untersuchten Altersstadien gleiche Gewichte. Beide waren durch vorangegangene Selektion auf Körpergröße weitgehend angeglichen. Die Variabilität des Gewichtes erwies sich bei den Linien C57BL und J als am geringsten, als intermediär bei FR und als am höchsten bei GR. Das Varianzmuster war bei allen Linien und für beide Geschlechter innerhalb des Untersuchungszeitraumes sehr ähnlich, mit einem Minimum bei der Geburt und einem Maximum am Ende der Wachstumsperiode (Inflexion). Das Schwanzwachstum zeigte die Linienunterschiede in gleicher Weise, lediglich der Stamm GR hatte eine größere Länge als FR. Das Öffnen der Vagina fällt zeitlich mit der Inflexion der weiblichen Tiere zusammen. Der Zeitpunkt der Inflexion differiert nicht zwischen den untersuchten Linien, scheint jedoch bei den weiblichen Tieren etwas früher als bei den männlichen zu liegen.

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Department of Animal Science.     

Modification toward dominance of a recessive lethal in the mouse.

The effect of the recessive siren (srn) gene singly in the presence of one Danforth's short tail (Sd) gene was to modify the expression of srn towards dominance with 46 percent penetrance. All mice that could be classified as sirens from srn/+ x Sd/+ matings had the Sd type short tail, indicating that interaction between Sd and srn was the principal cause for modification towards dominance of srn. External expressivity was variable in Sd srn pups, with true sirens, semi-sirens and apposed leg pups produced, each traceable to pelvic abnormalities. Variation in the urogenital system was similar to that found in siren pups with the srn/srn genotype.     

Hereditary erythroblastic anaemia in the laboratory mouse

Hereditary erythroblastic anaemia was found in a homozygous mutant (hea/hea) of an inbred strain CFO, which originated from noninbred CF#1 mice from Carworth Inc. This newly-described anaemia is inherited as an autosomal recessive and is lethal at 15-25 days of age. Erythrocytes of anaemic mice show striking polychromasia, anisocytosis, and poikilocytosis. One of the most marked features of this anaemia is the presence of large numbers of nucleated cells, mainly orthochromatophilic erythroblasts and myeloid cells, in the circulation. They also include immature erythroid and myeloid cells. Many naked nuclei appear on smears from circulating blood of anaemic infants. Erythrocytes, haematocrit percentage, and haemoglobin content of older anaemic infants were only about 50% of those of the normal. Formation of erythroid, myeloid cells, and megakaryocytes in the bone marrow seems to be progressively affected by mutant alleles in the anaemic infants.     

Plasma testosterone and male dominance in a Japanese macaque (Macaca fuscata) troop compared with repeated measures of testosterone in laboratory males

Plasma testosterone levels measured by radioimmunoassay did not correlate with dominance rank or aggressive behavior in 21 adult males of a natural troop of Japanese macaques (Macaca fuscata). The data were replicated during two consecutive breeding seasons. Levels of male dominance and aggressive behavior were highly correlated from year to year, but testosterone levels of individual males were not. Nor were individual levels of testosterone correlated in five laboratory males sampled every 15 min over a 2-hr period. These laboratory males showed multiple, apparently random peaks but the mean testosterone level of 11.73 ng/ml did not vary significantly throughout the 120 min that were studied. By demonstrating that the stress of blood collection did not depress plasma testosterone titers in laboratory males, these data validated the method used in the study of the natural troop.     

Competition for limited environmental resources on the social dominance model in laboratory mice

Asymmetry of social rank in the competition for food and female was studied using the social dominance model with only two male mice. Marking activity was recorded as a useful indicator of the social status. Social rank was determined by asymmetry in aggressive behavior. A food test was presented for 10 min daily within 5 days of the experiment, whereas a sexual test was performed only on the 5th day for 30 min. Marking behavior was estimated twice: before the first interaction and on the 4th day of the experiment. The competition for food was accompanied by active attacks, escapes, vertical defense postures, and sniffing. The level of aggression, sniffing, and food activity was higher in dominant than submissive males. Time course of aggressive, defensive, and sniffing behaviors was characterized by maximum scores in the period of formation of social hierarchy; however, the rate of food activity in this period was low and increased only to the 4th day. Introduction of a receptive female into the male group with the stable social hierarchy stimulated the intermale aggression, defensive and sniffing behaviors. Dominant males were characterized by a greater number of victories over and sniffing contacts with both male and female. Marking activity was also more intense in dominants. Thus, significant unidirectional rank differences in agonistic, sniffing, food, sexual, and marking behaviors were shown on the social dominance model with the minimum number of partners.     

Comparisons of butterfly richness and abundance measures in prairie and barrens

Transect surveys of adult butterflies were conducted along fixed routes at 27 study sites grouped into three subregions of tallgrass prairie and one subregion of pine-oak barrens in the midwestern USA. Within subregion, each site was visited the same number of times over 5–7 years on similar dates with similar weather. For each site, five indices of species richness and/or abundance were calculated both for total butterflies and for specialist species primarily restricted to native herbaceous vegetation. These indices were then analysed as to how much they agreed or conflicted in site ranking and how site rankings based on total butterflies compared to those based on specialists. Variation in site ranking by different indices was relatively low. Mean site rank by specialist indices covaried significantly with mean site rank by indices for total butterflies. Numerous studies have shown that on a regional scale, areas of higher richness for all species in a taxonomic group are different habitat types (based on amount of canopy or degree of degradation) from hotspots for that taxon's subset of species of conservation concern (endemics or specialists). But in this study, within a habitat type, site rankings based on total butterflies significantly tended to agree with site rankings based on specialist butterflies. This suggests that site prioritization and management favouring specialist butterflies would also favour the overall butterfly fauna possible in the same habitat.     

Immunity to Trichuris muris in the laboratory mouse

Of all the laboratory models of intestinal nematode infection, Trichuris muris in the mouse is arguably the most powerful. This is largely due to the fact that the ability to expel this parasite is strain dependent. Thus, most mouse strains readily expel T. muris. However certain mouse strains, and indeed some individuals within particular mouse strains, are unable to mount a protective immune response and harbour long term chronic infections. This unique model thus presents an opportunity to examine the immune events underlying both resistance to infection and persistent infection within the same host species, and in some cases, the same host strain.     

Hexamitiasis in a laboratory mouse colony

An acute fatal disease occurred in a mouse colony at the authors' institution. The disease caused 50% mortality among weanling mice, and was characterized clinically by depression, rough hair coat, and distention of the abdomen. The most prominent gross lesions were watery fluid and gas in the small intestine. Numerous organisms identified as Hexamita muris were seen in direct smears of the intestinal fluid. Microscopic and electron microscopic examination revealed the same organisms in the intestinal crypts, within the mucosal epithelium, and in the lamina propria. Treatment with dimetridazole controlled the clinical disease but did not eliminate the infection.     

Lifelong learning: ocular dominance plasticity in mouse visual cortex

Ocular dominance plasticity has long served as a successful model for examining how cortical circuits are shaped by experience. In this paradigm, altered retinal activity caused by unilateral eye-lid closure leads to dramatic shifts in the binocular response properties of neurons in the visual cortex. Much of the recent progress in identifying the cellular and molecular mechanisms underlying ocular dominance plasticity has been achieved by using the mouse as a model system. In this species, monocular deprivation initiated in adulthood also causes robust ocular dominance shifts. Research on ocular dominance plasticity in the mouse is starting to provide insight into which factors mediate and influence cortical plasticity in juvenile and adult animals.     

Little epistasis for anxiety-related measures in the DeFries strains of laboratory mice

Recent advances in methodologies for testing epistatic interactions, combined with several successes in demonstrating genetic interaction effects in animal and human genetics, have rekindled interest in the role of epistatic influences on complex traits. It has even been suggested that the unacknowledged presence of epistasis vitiates the genetic dissection of human and animal behavior. Here we report a genome-wide interaction analysis of 1636 F₂ mice to show that epistasis is of minimal importance in an animal model of anxiety. By using a sufficiently large sample of F₂ animals, we provide evidence that interaction effects between any two loci contribute less than 5% to the total phenotypic variance in multiple tests of anxiety. We conclude that interactions between loci do not necessarily vitiate the genetic analysis of behavior in at least one animal model of anxiety.     

Female dominance in captive gray mouse lemurs (Microcebus murinus)

Female dominance or female feeding priority seem to be characteristic for many lemur species, but are rare traits in other primates and mammals in general. The nocturnal lemur species, however, are underrepresented in the quantitative studies on social dominance. The aim of this study is to investigate the pattern of intersexual dominance relationships in the gray mouse lemur (Microcebus murinus), a species that is generally thought to possess a number of ancestral lemur traits. The context, distribution, and outcome of intersexual conflicts are analyzed in four captive groups of gray mouse lemurs. Intersexual conflicts occurred in the study groups in different behavioral contexts and were mostly spatial interactions (chasing/fleeing, approach/avoidance). The majority of conflicts were decided, and were in all but one case won by females. This is the first evidence suggesting unconditional female dominance in a cheirogaleid primate. The existence of female dominance in most families of the Lemuriformes suggests it is an ancient trait that evolved in their common ancestor.     

An imputed genotype resource for the laboratory mouse

We have created a high-density SNP resource encompassing 7.87 million polymorphic loci across 49 inbred mouse strains of the laboratory mouse by combining data available from public databases and training a hidden Markov model to impute missing genotypes in the combined data. The strong linkage disequilibrium found in dense sets of SNP markers in the laboratory mouse provides the basis for accurate imputation. Using genotypes from eight independent SNP resources, we empirically validated the quality of the imputed genotypes and demonstrated that they are highly reliable for most inbred strains. The imputed SNP resource will be useful for studies of natural variation and complex traits. It will facilitate association study designs by providing high-density SNP genotypes for large numbers of mouse strains. We anticipate that this resource will continue to evolve as new genotype data become available for laboratory mouse strains. The data are available for bulk download or query at /. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A genomewide functional network for the laboratory mouse

Establishing a functional network is invaluable to our understanding of gene function, pathways, and systems-level properties of an organism and can be a powerful resource in directing targeted experiments. In this study, we present a functional network for the laboratory mouse based on a Bayesian integration of diverse genetic and functional genomic data. The resulting network includes probabilistic functional linkages among 20,581 protein-coding genes. We show that this network can accurately predict novel functional assignments and network components and present experimental evidence for predictions related to Nanog homeobox (Nanog), a critical gene in mouse embryonic stem cell pluripotency. An analysis of the global topology of the mouse functional network reveals multiple biologically relevant systems-level features of the mouse proteome. Specifically, we identify the clustering coefficient as a critical characteristic of central modulators that affect diverse pathways as well as genes associated with different phenotype traits and diseases. In addition, a cross-species comparison of functional interactomes on a genomic scale revealed distinct functional characteristics of conserved neighborhoods as compared to subnetworks specific to higher organisms. Thus, our global functional network for the laboratory mouse provides the community with a key resource for discovering protein functions and novel pathway components as well as a tool for exploring systems-level topological and evolutionary features of cellular interactomes. To facilitate exploration of this network by the biomedical research community, we illustrate its application in function and disease gene discovery through an interactive, Web-based, publicly available interface at http://mouseNET.princeton.edu.