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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The electrokaryotype and molecular characterization of Trypanosoma cervi isolates using recombinant DNA techniques

Bennett, J. Lindsley 01 January 1990 (has links)
The distribution of trypanosomes infecting wild ruminants of North America has only recently been investigated . Many isolates have been mensurally studied and were determined to be conspecific with Trypanosoma cervi. Widely divergent forms exist however, between host species and seasonally within a host . To determine the validity of all inclusions in the taxon and the extent of intraspecific variability , trypanosome isolates of moose, reindeer , antelope, muledeer, Roosevelt Elk and two discrete transplant populations of Rocky Mountain elk were characterized and differentiated using recombinant DNA techniques.
2

Morphological and Genetic Comparisons between Babesia bovis and Trypanosoma spp. Found in Cattle and White-tailed Deer

Fisher, Amanda 2012 August 1900 (has links)
Babesia bovis has been an important disease agent in the U.S. cattle industry for over a century. Recently, B. bovis-like parasites have been identified in white-tailed deer (WTD; Odocoileus virginianus) in Texas. If the parasites found in the WTD are B. bovis that are able to infect cattle, the disease could re-emerge. Susceptible adult cattle often die from this disease, which would result in severe production losses, as well as a decrease in carcass weights of disease survivors. The B. bovis-like parasite found in WTD was compared to B. bovis from cattle, by ribosomal DNA sequence analysis. Babesia isolated from WTD were found to have 99% identity to B. bovis from GenBank cattle sequences. No cattle samples in this study were found to be positive for B. bovis. On culture of WTD samples, a Babesia parasite could not be visualized based on common morphological features. Trypanosoma cervi has been studied for decades, but all the previous research identified this parasite solely by morphology. Trypanosoma species obtained from different host species was compared by ribosomal DNA sequence analyses. In this study, the Trypanosoma cultured from WTD had the morphological appearance of T. cervi. On sequence analysis, the cattle sequences aligned together with cattle isolates and the WTD sequences aligned closely with elk (Cervus canadensis) sequences, indicating that wild ungulates (WTD and elk) and cattle most likely have separate trypanosome species. On distribution analysis there was a trend in three South Texas counties, where the county with the highest occurrence of Trypanosoma had the lowest occurrence of Babesia; and vice versa. It is possible that Trypanosoma and Babesia blood parasites compete within the mammalian host, but the chi-squared test did not show a significant association between the two parasites in the different counties. On seasonal analysis, the correlation between positive samples and season could not be statistically confirmed, but it appears that Babesia infected animals are found in lowest numbers during hot, dry seasons. It also appears that there is another vector for Trypanosoma in South Texas besides the ked (Lipoptena mazamae) and tabanid fly (Tabanus spp.).
3

<i>Acropora</i> Habitat Evaluation and Restoration Site Selection Using a Species Distribution Modeling Approach

Wirt Ames, Katherine 28 March 2016 (has links)
While populations of nearly all stony coral species along the Florida reef tract have exhibited decline, the most notable decline has occurred in the once-dominant acroporid species (Acropora cervicornis, A. palmata). Both species were listed in 2006 as threatened under the Endangered Species Act. This listing, combined with their continued decline, has resulted in large-scale restoration efforts throughout Florida and the Western Caribbean. Currently, there is little to no information regarding spatial prioritization of sites for these restoration efforts. The primary objective of this dissertation was to utilize species distribution modeling, informed by existing data from the Florida reef tract, to identify sites for restoration of acroporid corals that should have strong likelihood for success. The initial focus was to use a database of reported field observations, in combination with benthic habitat maps, to model the extent of suitable habitat for Acropora spp. The mapped coral reef and hardbottom classifications throughout Florida, Puerto Rico, and the US Virgin Island reef tracts were used to generate potential-habitat polygons using buffers that incorporated 95% and 99% of reported observations of Acropora spp. Resulting maps demonstrated that A. palmata habitat is relatively well defined, while that of A. cervicornis is more variable and difficult to constrain. Thus, as the major focus of this dissertation, available monitoring data from the Florida reef tract were used to construct and compare two types of statistical species distribution models, random forest and boosted classification trees, as an approach to inform siting of restoration efforts for A. cervicornis. Boosted classification trees were more accurate than the random forest model at classifying A. cervicornis population trends. Further analyses of the two most important environmental parameters identified by the model, depth and light availability, revealed that reef areas predicted to not have had A. cervicornis present from 1996-2013 were deeper, on average, and had lower light availability and greater variance than areas predicted to have had continuous or transient A. cervicornis presence over this time frame. This study represents a first step at deriving an ecologically-guided approach to spatial prioritization of restoration efforts. The overarching goal of this project has been to design a strategy for creating models to define and predict where conservation and restoration actions should be most effective, that can be utilized for a variety of coral species. With existing populations mapped, the results can also aid in protecting the limited areas in which these species still occur.

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