This study was undertaken primarily to examine the skeletal and muscular anatomy of a small species of field mouse, Microtus oregoni serpens Merriam, which inhabits the Puget Sound area of British Columbia and Washington. This species is largely subterranean in its habits and in an attempt to discern the degree of specialization for its habitat comparison was made between serpens and Microtus townsendi townsendi, (Backman) and Microtus longicauda vellerosa (Allen) species which burrow to a limited degree only. A detailed comparison of the external features, skeletal and muscular anatomy of the three species was made and a juvenile specimen of Microtus richardsoni richardsoni, (De Kay) was used for some comparisons. Certain parts of Microtus oregoni serpens were found to be strongly modified in a direction which seems to better adapt the animal to its subterranean mode of life. The external features which are of adaptive significance are the soft plush-like pelage, the short tail and the arrangement of the vibrissae the longest ones being furthest from the snout rather than scattered. The eyes are only about one-half the size of those of the larger species and associated with them is an interesting modification of the orbicularis oculi muscle whereby it is strongly developed doubtless as an aid in preventing dirt from entering the eyes. Microtus oregoni serpens does not have conspicuously enlarged or elongated fore-feet but among the modifications for digging which do occur are the shortening of the limbs and the inclusion of a larger part of them within the body skin. Almost the entire musculature of the anterior segment of the body is more strongly developed in serpens including the muscles of the shoulder, chest, and fore-limbs and to some extent the masticatory musculature and the musculature of the spinal column. The muscles attached to the pectoral girdle show the most marked modifications they are almost universally better-developed in serpens than in townsendi or longicauda. Correlated with a greater development of the pectoralis muscles is the development of a heel on the manubrium sterni and the sternebras in serpens, providing a larger area for muscle attachments. Microtus oregoni serpens seems to represent one of the earliest stages of adaptive specialization of a mammal for subterranean life externally approaching the condition found in specialized burrowers such as the mole but having no radical skeletal modifications. / Science, Faculty of / Zoology, Department of / Graduate

The Distal-less homeobox (Dlx) genes encode a group of transcription factors that are involved in early vertebrate development of limbs, sensory organs, branchial arches and the forebrain. In the forebrain, four Dlx genes, Dlx1, Dlx2, Dlx5, Dlx6, play essential role in the differentiation and proper migration of GABAergic interneurons to the cortex. Dlx genes are organized in convergently transcribed bigene clusters and each cluster includes a short intergenic region harboring cis-regulatory elements (CREs): specifically, the Dlx1/2 cluster includes I12b and I12a CREs, while Dlx5/6 harbors I56i and I56ii. In an effort to determine the regulatory role of the CREs on Dlx expression and forebrain development, I characterized mice with an I56i deletion and both I12b and I56i deletions. At late embryonic stage (E18.5) and the adult stage (P35), both mutants had similar expression levels of Dlx2 and Gad2 gene, encoding enzyme glutamic acid decarboxylase that is responsible for synthesis of GABA. Mutant mice showed impaired expression levels of Dlx5. The expression levels of Gad1 were decreased in ΔI56i mutants but increased in ΔI12b/I56i mutants at E18.5, and both adult mutants had comparable expression of Gad1 as wildtype mice. Together with previous in situ hybridization results of mice at earlier stages (E11.5, E14.5), my data show that Dlx CREs have different levels of activity in regulating the expression of Dlx genes at different developmental stages. The mutations of I56i and I12b CREs did not affect the development of two subtypes of GABAergic neurons (calbindin and calretinin expressing neurons) in the forebrain. Compared to wildtype mice, both mutants had hypersociability and deficits of memory and learning ability. This opens the possibility that the deletions of Dlx intergenic CREs caused some developmental abnormalities and, therefore affected the behavior of the mice. Through studying the mice lacking Dlx intergenic CREs, I gained a better understanding of the role that I56i and I12b play in the regulation of the expression of Dlx genes, the development of GABAergic neurons, and the social and cognitive behavior.

Plicatic acid and 5-isopropyltropolone, which are found in the heartwood of western red cedar (Thuja plicata, Donn), are known chelators of copper. A study has been made of their effects on some aspects of copper metabolism in rats and mice. As a basis of comparison similar experiments were carried out using penicillamine (PEN), a chelating agent with wide clinical use. In the experiments the sodium salt of 5-isopropyltropolone (T-Na) and the potassium salt of plicatic acid (P-K) were used. When administered daily, P-K and PEN caused an increase in urinary and fecal excretion of copper in rats on a normal diet and an increase in the level of copper in the liver and kidney and a decreased level of copper in the heart and brain. The increased urinary excretion is much more marked with PEN than with P-K. T-Na administered daily had no effect on the excretion of copper in rats on a normal diet and causes a rise in copper content of liver and kidney and a lowering of copper content of heart and brain. It appears that the copper level elevation in kidney and liver caused by P-K and PEN is due to an increased utilization of the routes of excretion while the increased level due to T-Na is probably due to deposition in the cells. When these compounds are administered daily to copper-fed rats similar observations were made with the difference that in organs where copper levels are increased the increases are greater and in organs where copper levels are decreased the decreases are smaller. With T-Na there is one marked difference in that the copper level in the brain is increased. It is felt that this increase is due to a greater penetrating ability of the T-Na-copper chelate because of its lipid solubility. P-K and PEN have very little effect on the toxicity of a single large dose of copper. Earlier experiments with T-Na showed that when T-Na is given shortly after a single large dose of copper the toxicity is greatly increased. The explanation of this is very likely that T-Na increases the penetration of the copper into the CNS and it is here that the toxic effect is exerted. It is felt that this is due to a solubility factor, T-Na and its chelate being lipld-soluble and P-K, PEN and their chelates being water-soluble. When T-Na, P-K and PEN are given to rats in small daily doses over a long period, the atria from such rats exhibited a reduced chronotropic response to tyramine. If at the same time as the rats are being given the chelating agent, they are given excess copper in drinking water the tyramine response remains close to normal. In this regard T-Na possesses the most activity. These observations support the theory that chelating agents inhibit dopamine-β-hydroxylase by rendering copper inaccessible to the enzyme and that subsequent to this inhibition the biosynthesis of the catecholamines is inhibited at the dopamine stage preventing the formation of norepinephrine and epinephrine. As the levels of endogenous norepinephrine and epinephrine fall, the result is a reduced tyramine response. If T-Na, P-K, PEN and D-Na are given in a large single dose the inhibition of dopamine-β-hydroxylase is not evident while it appears that COMT may be being inhibited. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

The paired preputial glands of the albino mouse, Mus musculus, (Swiss strain) were studied with regard to histology, physiology and basic histochemistry. For the histological study of the development and subsequent aging of the preputial gland, the glands of male and female mice of different ages, ranging from newborn to 12 months old, were used. In order to study the effects of androgens and estrogens upon the macroscopic and microscopic structure of the preputial gland, white Swiss mice were divided into four major groups (according to age and status) each of which were, in turn, divided into subgroups a, b, c, and d for treatment; mice in subgroups a and b received daily subcutaneous injections of testosterone propionate and of estradiol benzoate respectively; mice in subgroup creceived daily subcutaneous injections of the vehicle, sesame oil; mice in subgroup d served as controls. There were, of course, male and female mice in each grouping. Routine histochemical tests for lipids and proteins were carried out on the excised preputial glands of weanling and of young adult mice, of both sexes, in order to localize and to identify the secretory products of the acinar cells. Histologically and physiologically (in terms of response to androgens and estrogens) the preputial glands of the mouse are similar, in most respects, to those of the rat as described by other authors. However, there are apparent differences in the microscopic anatomy and in the histochemistry of these homologous organs; firstly, the presence of an intimate association of the mouse preputial gland with a central hair follicle which persists throughout the lifetime of the animal and which is not found in the rat gland; secondly, the absence of perinuclear proteinaceous granules in the acinar cells of the mouse preputial gland which are present in the acinar cells of the rat preputial gland, in addition to lipid droplets. Lipids, primarily in the form of droplets of neutral fats are, to my knowledge, the only secretory products of the mouse preputial gland. Developmentally, histologically, and histochemically, the preputial gland of the mouse is an excessively developed sebaceous gland and unlike the rat preputial gland which cannot be categorized so simply, belongs to the "monocrine" variety of holocrine gland. / Science, Faculty of / Zoology, Department of / Graduate

The populations of cells which infiltrate tissue allografts in W mutant mice and their non-mutant littermates were investigated using the light and electron microscopes. Initially, thyroid allografts were attempted but this tissue proved unsatisfactory for comparative studies and skin was used instead. The cells infiltrating the skin grafts were isolated enzymatically and characterized using the light microscope. In addition, cells in epon sections of skin grafts were identified using the electron miscroscope. The frequency of the various cell types isolated from grafts in mutant mice differed significantly from that of cells isolated from grafts in non-mutant mice. The electron microscope studies indicated that the cell types infiltrating skin allografts are the same in both mutant and non-mutant hosts. / Science, Faculty of / Zoology, Department of / Graduate

Chlamydia trachomatis is a leading cause of bacterial genital infection in the US and worldwide. The chlamydial replication cycle is biphasic, meaning it enters the host cell as an infectious elementary body (EB), differentiates into an actively dividing reticulate body (RB) inside of a vacuole-like compartment, called a chlamydial inclusion, and differentiates back into EB form before exiting the host. Studies have demonstrated that estrogen aids Chlamydia infection in human and swine endometrial cells and in guinea pigs. Our prior data showed that antibody blockage of estrogen receptors or exposure to the ERβ antagonist tamoxifen in vitro decreased the development of chlamydial inclusions. Given these observations, we wanted to further examine the role of ER signaling on chlamydial infection in a murine model. We hypothesized that the absence of estrogen receptors would alter the establishment and/or progression of chlamydial infection in mice. To test this hypothesis, we compared C. muridarum infection in wild type (ERαWT or ERβWT) versus knockout (ERαKO or ERβKO) mice. Groups of eight ERαWT, ERβWT, ERαKO, or ERβKO mice were Depo-Provera treated seven days prior to vaginal infection with C. muridarum. Vaginal swabs were taken every three days for 21 days to monitor infection by EB titer analysis. Interestingly, titer data showed that peak EB shedding occurred earlier in the ERαKO mice compared to the ERαWT. At day 3 pi, EB shedding from ERαKO mice was 12-fold greater than shedding from ERαWT mice. On day 6, however, ERαWT mice shed >3-fold more EB than ERαKO mice. Conversely, there was no significant difference observed in ERβKO versus ERβWT mice or in ERαKO versus ERβKO mice. In a subset of experiments, genital tracts were collected on day 9pi and processed for flow cytometry analysis of the immune response to infection. ERαKO mice had significantly more monocytes and macrophages than ERαWT and ERβKO mice, as well as significantly more T cells than ERβKO mice. There was no significant difference in the immune cells in ERβKO and ERβWT mice. Together, these data suggest that: 1) the absence of ERs in mice does not inhibit chlamydial infection as has been observed in human cells in vitro; and 2) C. muridarum infection progression is affected by ERα signaling, possibly via alterations in the immune response.

The objectives of this study were: (1) to make a detailed study of the distribution of the genus Parognathus in Utah; (2) to determine if any species or races not now recorded occur in the state; (3) to bring together notes on life histories of this genus, both from the literature and field studies; and (4) to determine habitat preferences of the species represented. This paper lists 14 subspecies belonging to 7 species of Perognathus occurring in Utah. One species is a new occurrence record, Perognathus fasciatus callistus, from northeastern Utah east of the Green River. The ranges of Perognathus longimembris, P. parvus, and P. formosus have been extended in Utah. Most of the pocket mice in Utah are found at an elevation of 6,000 feet or less. Perognathus parvus is the most widely distributed of any of the species and may be found at elevations as high as 10,000 feet. The other species appear to prefer special habitats. One group of P. parvus from the east slope of the Henry Mountains is believed to contain sufficient taxonomic traits to warrant separation into a new race. The reproductive cycle of the Utah species appears to be from April to July reaching its peak in June. There is little evidence that pocket mice have more than one litter per year. As a rule pocket mice are relatively free of ectoparasites. However, ticks, mites, lice, and fleas were taken from some of the Utah specimens.

The parasitic mites on mammals living in the chaparral community of Utah are practically unknown ecologically. Keegan (1953) was the first to publish on parasitic mites from Utah. He listed mites of 12 species and 9 genera from Tooele and Juab counties from hosts which included one Peromyscus truei, five P. crinitus, and 20 P. maniculatus. Brennan and Beck (1955) published on the chiggers of Utah and included a key to 38 species. Allred (1954, 1956, 1957, 1958) studied the geographical distribution, seasonal occurrence, and biology of mites found on mice of the genus Peromyscus in Utah.

Intraspecific competition is important in determining habitat utilization by members of a single species. Effective use of habitat may involve partitioning the available resources: space, time and food among individuals of different age, sex, and/or reproductive state. Numerous publications deal with interspecific competition (McCloskey and Fieldwick 1975, Cody 1973, Rosenzweig 1973, Stewart and Levin 1973, Gaby 1972, Brown 1971, Koshkina 1971, Sheppe 1967, Caldwell and Gentry 1965, Cameron 1964, Clough 1964, Gause 1932), but little has been written on intraspecific competition among populations of organisms in nature.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2018 / The morphological variation between populations is shaped by adaptive responses to prevailing environmental conditions and/or not adaptive stochastic effects. Within-population variation is mainly related to age and sexual dimorphism, as well as temporal and spatial variation in environmental conditions. The aim of this study was to investigate patterns of variation in the skull, mandibles, and dentition in a population of the African four-striped mouse Rhabdomys dilectus chakae. Geometric morphometrics was used to assess the variation related to allometry and age, sexual dimorphism, and the inter-annual variation between specimens collected in different years (1975, and 1994-1997). A review of the literature on the application of geometric morphometrics to rodent morphological variation was conducted and landmark morphometrics were concluded to be the most appropriate methods for the skull and the mandible analyses, with a separate analysis using landmarks and semi-landmarks to analyse the variation of mandibular curves, and outline morphometrics with an Elliptic Fourier analysis of the upper molars. Images of the skull (ventral and lateral view at 5x magnification), mandible (at 6.8x magnification), and the three left upper molars (at 10.5x magnification) were captured using a stereoscopic microscope. Landmarks were digitized on the skull and mandible images, with semi-landmarks digitized on mandible images, and outlines were digitized on molars. Multivariate analysis of variance was used to analyse shape and size variation due to age, sex, and year of sampling and a multivariate regression was used to analyse allometry. A PCA was used to visualize shape variation, and boxplots of log-centroid size to visualize size variation between age classes, sexes, and years of sampling. Shape variation was significantly predicted by age and year of sampling, while size was significantly predicted by age, sex, and year of sampling. Size significantly contributed to shape variation, although size alone did not appear to explain much of the variation present. Most age-related variation in shape was due to differences between the first three age classes and age class IV, while size increased with increased age (i.e. growth). Males were larger than females although no sexual shape dimorphism was evident between sexes. Typical of species with male-male competition, Rhabdomys dilectus chakae demonstrated sexual size dimorphism; larger males have greater mating opportunities. Specimens from 1994 and 1997 had more variable shapes and were consistently smaller than those collected in 1975, 1995 and 1996, except for dentition where these latter specimens were smaller than those collected in 1994 and 1997. Annual variation in morphology may be a plastic response to prevailing local climatic conditions (i.e. rainfall and temperature), Masters Dissertation Candice Neves iv resulting in annual variation in diet, affecting the skull and dentition. Further studies should consider more populations in the species to assess the generalizability of the findings, particularly annual variation, and to consider spatial variation across the distribution of a population. / GR2019