Despite the fact that eight cases of Lyme disease were diagnosed in San Luis Obispo County between 2005-2013, the identity of wildlife hosts serving as sources for tick infection in this region remained unidentified. The primary cause of Lyme disease in the U.S. is the spirochetal bacterium Borrelia burgdorferi sensu stricto, and this agent had not been previously isolated from the region. Borrelia bissettii, a related species that has not been implicated as a common causative agent of Lyme disease, was isolated in small rodents inhabiting coastal scrub and chaparral habitats in a previous San Luis Obispo County study. However, B. burgdorferi was not detected. In northwestern California, B. burgdorferi has been primarily associated with high populations of the tick vector Ixodes pacificus in dense woodlands or hardwood-conifer habitats, particularly in the western gray squirrel reservoir host, Sciurus griseus. My study investigated the role of S. griseus and other associated rodents as potential reservoirs for B. burgdorferi in central coastal California woodland habitats. Rodents were live-trapped at four sites in San Luis Obispo County in oak and mixed woodland. Rodent ear samples were tested for B. burgdorferi genospecies by bacterial culture and PCR. Ticks were collected from captured rodents and surrounding environments and tested by PCR for the presence of Borrelia. Of 119 captured rodents, seven were positive for Borrelia infection (5.9%) and of these, six were positive for B. burgdorferi (5.0%). There were multiple infected rodent species that included two western gray squirrels, three deer mice (Peromyscus maniculatus), and one brush mouse (P. boylii). Borrelia spp. were not detected by PCR from the 81 ticks recovered from the environment and rodents. Here, for the first time, we verify the presence of B. burgdorferi sensu stricto in San Luis Obispo county rodents. However, in contrast to previous Northern California studies, the western gray squirrel may not be the primary reservoir host for B. burgdorferi in this region. Multiple rodent species in oak woodlands may be involved in spirochete maintenance in San Luis Obispo County.

Emerging or re-emerging tick-borne pathogens are expected to increase in prevalence and become more geographically widespread in Canada. Borrelia burgdorferi, the bacterium causing Lyme disease, is the most common vector-borne pathogen in North America, but additional tick-borne pathogens have started to be detected more frequently through surveillance efforts in Canada. The spread and transmission of these tick-borne pathogens are modulated by changes in the abundance and distribution of tick and host populations. Abiotic factors, such as temperature, precipitation, and snow, may affect tick and host abundances as well as host dispersal. Furthermore, biotic factors, such as the abundance and diversity of hosts, may alter tick abundance and consequent tick-borne disease risk. In this dissertation, I assess the historical associations and spatiotemporal changes of the tick vectors, hosts, and pathogens in Canada as well as the impact of abiotic and biotic factors on these key players. In Chapter 1, I present the first systematic assessment of the literature that identifies historical associations and spatiotemporal changes in the tick-host-pathogen disease systems in Canada over broad spatial and temporal scales. Borrelia burgdorferi was the most detected tick-borne pathogen and Ixodes scapularis harboured the greatest number of tick-borne pathogens. Several spatial outliers of high pathogen presence in ticks in addition to five spatiotemporal clusters were identified, which were located in areas of southern Canada with long-established tick populations. In addition, six spatiotemporal clusters of high pathogen presence were also identified, with four clusters associated with passive surveillance and two clusters related to active surveillance. In chapter 2, I concurrently evaluated high-resolution environmental and host-related factors to determine the relative impacts of abiotic and biotic factors on questing I. scapularis abundance in Ontario and Quebec. High-resolution abiotic factors were derived from remote sensing satellite imagery and meteorological towers, while biotic factors related to mammal hosts were derived from active surveillance data that I collected in the field. Important abiotic and biotic drivers of questing I. scapularis abundance were identified, which included monthly mean precipitation, accumulated snow, and mammal species richness. These results demonstrate the need to incorporate host active surveillance data with high-resolution environmental factors when trying to determine the key drivers impacting the abundance and distribution of tick populations and tick-borne pathogens. In Chapter 3, I analyzed the presence and prevalence of multiple tick-borne pathogens extracted from tick and small mammal specimens collected during field surveys in Ontario and Quebec. Three pathogen species were detected in ticks, which included Babesia odocoilei and B. burgdorferi in I. scapularis as well as Rickettsia rickettsii in Haemaphysalis leporispalustris. In small mammal hosts, three pathogen species were detected including B. odocoilei in one shrew, B. microti in one deer mouse, and Hepatozoon in one deer mouse and one white-footed mouse. My findings provide evidence that emerging or re-emerging tick-borne pathogens may be present outside currently defined risk areas identified by surveillance efforts in Canada. Finally, in chapter 4, I examined the effect of biotic factors related to I. scapularis and mammal hosts on the presence, prevalence, and diversity of pathogens in Ontario and Quebec using data from field surveys. Local infection prevalence ranged from 0% to 25.4% in questing ticks and from 0% to 16.7% in small mammal hosts. Local pathogen presence and prevalence were not impacted by I. scapularis abundance nor the abundance and diversity of mammal hosts. However, mammal species richness was a key predictor of the number of pathogen species. Collectively, my dissertation provides insight into the historical and contemporary relationships between ticks, hosts, and pathogens in Canada. My results demonstrate that additional tick species such as H. leporispalustris may be of public health importance due to their ability to maintain pathogens within the environment without needing a host. In addition, certain emerging or re-emerging tick-borne pathogens, such as B. odocoilei and R. rickettsii, were detected outside of currently defined risk areas in southeastern Quebec, which may impact future surveillance efforts in these regions. Furthermore, this work highlights the need for proactive and comprehensive surveillance efforts that test questing and feeding ticks of all life stages and species, as well as their hosts in areas outside currently defined risk areas or those targeted by sentinel surveillance to better determine the spread, transmission, and co-occurrence of tick-borne pathogens in Canada.

The characterization of rodent cell mutants hypersensitive to UV light has led to the identification of at least 10 complementation groups all defective in some aspect of the first step in the excision repair of UV damaged DNA. The phenotypic properties of these mutants are thus of considerable importance to our understanding of DNA repair. In recent years five different excision repair cross complementing (ERCC) human genes have been isolated which correct the DNA repair deficiency in a number of Chinese Hamster Ovary (CHO) cell mutants and at least three of these genes also complement the repair deficiency in cells from patients suffering from xeroderma pigmentosum (XP), Cockayne syndrome (CS) and/or Trichothiodystrophy (TTD). Adenovirus (Ad) infection of rodent cells is generally semi-permissive and does not give rise to viral progeny, such that Ad reactivation in CHO cells has not previously been reported. This study utilizes the ability of CHO cells and human cells to replicate viral DNA in order to examine the reactivation of Ad in several CHO as well as human cell DNA repair mutants. Unirradiated and UV-irradiated suspensions of Ad were assayed for their ability to synthesize viral DNA following the infection of several CHO and human cell DNA repair mutants. The cell types examined included CHO cell mutants from complementation groups 1, 2, 3, 4, 5, 6, 9, 10 as well as human XP and tumour cells. The survival of viral DNA synthesis for UV-irradiated Ad was significantly reduced in several of the CHO and human cell mutants compared to that in normal cells. Cell mutants showing a reduced UV survival for this viral function included CHO cell mutants from complementation groups 1 to 6, XP cells and the 2 human tumour cell lines examined. This reduced host cell reactivation (HCR) for Ad indicates a reduced capacity for the repair of viral DNA in these cell types. DNA replication for unirradiated virus was also reduced for some of the mutants, especially the UV20 CHO cell mutant from complementation group 1, suggesting a deficiency for both DNA replication and repair in these cells. This study also used the recombinant viruses Ad5(denV) and Ad5(ERCC1) as vectors to examine the effect of the bacteriophage T 4 denV gene and the human ERCC1 gene on viral reactivation in the various cell mutants. UV survival of Ad5(denV) was increased compared to that of the control Ad5(LacZ) following infection of all the CHO and human cell types examined, indicating the denV gene product increases repair of Ad in both repair-proficient and repair-deficient cells. UV survival of Ad5(ERCC1) was increased compared to that of control Ad5(LacZ) following infection of the CHO mutant UV20 from complementation group 1, as well as all CHO cell types having normal HCR for AdS. However, UV survival of Ad5(ERCC1) was not increased compared to Ad5(LacZ) following infection of CHO mutants from complementation groups 2 to 6 and 10. These results support a specific complementation of the UV20 repair defect by ERCC1 and suggest that the human ERCC1 gene is more efficient than its hamster counterpart in repair-proficient CHO cells or that the ERCC 1 product is rate-limiting for the excision repair process in CHO cells. UV survival of Ad5(ERCC1) was also increased compared to Ad5(LacZ) in the normal human fibroblast cells and human tumour cells, but not in the XP (group D) cells. The kinetics of viral DNA synthesis and viral protein synthesis for unirradiated Ad5(denV) and Ad5(ERCC1) was also investigated following the infection of human and rodent cells. The deficiency in viral DNA synthesis and viral protein synthesis found for AdS(LacZ) following infection of rodent compared to human cells is partially complemented by either denV or ERCC1. The more marked deficiency in viral DNA synthesis of the UV20 CHO mutant was also complemented by either ERCC1 or denV, suggesting an ability of these genes to function in both repair and replication of viral DNA. / Thesis / Master of Science (MS)

No description available.

Thesis (Ph. D.)--Montana State University--Bozeman, 2004. / Title from PDF t.p. (viewed on June 12, 2006). Chairperson, Graduate Committee: Daniel Goodman. Includes bibliographical references (p. 189-207).

Thesis (M.S.)--University of Alaska Fairbanks, 2005. / Title from PDF t.p. (viewed Aug. 22, 2006). Includes bibliographical references (p. 59-67).

No description available.

The neuropeptide hormone oxytocin plays an integral role in mammalian reproductive endocrinology and behaviour. It has been utilised to study the physiological factors driving maternal behaviour in both laboratory and domestic mammals, but few studies have successfully detected oxytocin in wild individuals, or linked detected concentrations to the behaviours they exhibit. Phocid seals present an excellent system in which to study oxytocin's effects on maternal behaviour in the wild. The energetic constraints placed on a phocid mother during the dependant period should cause strong selection pressure for behaviour that maximises reproductive success with the least cost to the mother. However in many phocid species, substantial variations in maternal behaviour persist. In order to investigate whether oxytocin plays a role in driving this variation, behavioural and hormonal datasets were collected from grey seal mothers and pups on two breeding colonies in Scotland. A protocol for the detection of plasma oxytocin in phocid seals was successfully developed, along with the methodology to manipulate peripheral oxytocin concentrations to directly test the hormone's impact on behaviour. Both correlatory studies on natural oxytocin concentrations and behaviour in wild mother-pup pairs and manipulation experiments on newly weaned pups show that plasma oxytocin concentrations influence behaviours that makes mother – pup separation less likely. These include increasing the time spent in close proximity to each other, increasing the number of checks performed on the pup and reducing the aggressive behaviour directed towards the other individual. Additionally, plasma oxytocin could be used as an indicator of weak maternal bonds between mother and pup, which resulted in behaviours such as abandonment and fostering. This study highlights the potential of oxytocin for studying variations in behaviours critical to an individual's reproductive success and provides the methodological framework for studies on other wild species to be conducted in the future.

A large proportion of the earth's surface is dedicated to food production, and agriculture is widely acknowledged to influence local biodiversity via habitat loss and degradation. Landscape genetics is an emerging field which can provide detailed understanding of how wildlife populations are influenced by landscape configuration and composition but the approach is yet to be fully integrated with agroecology. When addressing landscape genetics questions, small mammals may provide insight; they may act as model organisms, they are abundant, they are relatively easy to sample and they may have important ecological roles within arable ecosystems. This thesis merged the study of arable landscapes, landscape genetics and small mammals, to develop what is known about the landscape genetics of wild species in this dynamic habitat type. To decide upon a study organism, small mammals were surveyed at an example arable field site. Wood mice (Apodemus sylvaticus) were found to be the most abundant species and a microsatellite marker multiplex was developed for genotyping individuals. Two aspects of their landscape genetics in arable habitat were investigated. First, the possibility of temporal patterns in fine scale genetic structure of arable populations was explored, since this had not been investigated previously. Next, inter-population genetic differentiation was examined to determine whether arable habitat acted as a barrier to gene flow for this species. At the fine scale, three genetically distinct clusters of wood mice were identified and temporal variation in the spatial pattern was confirmed. There was no evidence that arable habitat acted as a barrier to gene flow for this species in comparison to populations in urban habitat, which showed significant differentiation. It is hoped that the landscape genetic insights provided by this thesis will encourage greater momentum for conducting landscape genetics studies in agricultural habitat.

Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Habitat heterogeneity is a key driver of biodiversity in many ecosystems. In native ecosystems, habitat heterogeneity can arise from multiple drivers including nutrients, topoedaphic conditions, and ecological disturbance. Historically, the prairies of North America existed as a heterogeneous mosaic of habitat conditions created by the interaction of fire and grazing by native ungulates. The focus of many grazing systems has been to minimize disturbance caused by grazing by promoting uniform distributions of grazing animals across management units. Patch-burn grazing is an alternative rangeland management practice that has been proposed to restore historical patch dynamics and biodiversity to rangelands by simulating historical disturbance processes. In my dissertation research, I tested the hypothesis that patch- burn grazing restores habitat heterogeneity to rangelands, and that the resulting habitat heterogeneity can promote biodiversity of native wildlife. I focus on responses of small mammals and coyotes to patch-burn grazing to gain a better understanding of wildlife responses to rangeland management, and because grassland mammals are an ecologically important group. My 3.5-year field study of habitat and small mammal responses to rangeland management showed that: 1) patch-burn grazing created greater heterogeneity in vegetative structure and composition of plant functional groups than in positive and negative controls; 2) habitat heterogeneity created by the interaction of fire and grazing increased small mammal richness and diversity compared to a negative control managed for uniform grazing distributions; 3) the interaction of fire and grazing structured small mammal communities in tallgrass prairie; and 4) population dynamic responses of small mammals to fire and grazing disturbance were species- specific. My 3-year study of coyote survival and resource selection revealed that: 1) rangeland management influences resource selection by coyotes in seasons when they depend on small mammal prey, but not during other seasons; and 2) anthropogenic sources of mortality are important for coyotes at a protected area, even in the absence of harvest. My field results show that restoring the drivers of historical patch dynamics to managed rangelands and publicly held grasslands that are not currently grazed could have profound effects on biodiversity conservation in North America, while continuing to provide ecosystem services to society.