This study assessed the influence of terrestrial invertebrate abundance and vegetation characteristics on northwest Minnesota greater prairie chicken brood success. Radio telemetry was used to determine movements of greater prairie chicken hens and their broods. Invertebrate abundance indices were collected using a sweep net and vegetation data were recorded with overhead and dot-board photographs. Invertebrates were dried, sorted by size and order, and weighed and counted. Vegetation was classified according to life form and height was measured. Greater prairie chicken broods appear to use those habitats most readily available with increased invertebrate resources. Invertebrate biomass was not related to the occurrence of uncultivated forbs which averaged < 17% in Minnesota habitats where greater prairie chicken broods were located. Relatively undisturbed grasslands produce sufficient invertebrate resources to fledge greater prairie chicken chicks. However, location data and invertebrate-habitat indices suggest increased brood success would be likely with improved habitat placement/availability and irregular disturbance regimes that produce beneficial mixed grass/forb vegetation attractive to both greater prairie chicken broods and their invertebrate prey.

In birds, estrogen is a strong stimulator of gene programs that regulate the formation of very low density lipoproteins (VLDL). Apolipoprotein-B (ApoB) is an integral part of very low density lipoproteins. In mammals, the rate of ApoB synthesis is controlled by post-translational means. In contrast, estrogen treated birds show changes in ApoB transcript level; in a natural setting, the bird?s metabolism and transcription are in great flux due to yolk formation. Besides the ApoB gene, the entire complement of genes that is necessary to form a VLDL is not known. To determine the genes that play a role in the formation of VLDL 7-10d old chicks were injected with estrogen at several time points over a 24hr period. Following exsanguinations by cardiac puncture, livers were removed and RNA was extracted. The RNA was quantified and hybridized to microarrays using a dual-dye system. Slides were scanned and analyzed, and features were extracted. To qualify microarray results, quantitative real time PCR (q-RTPCR) was done on a selection of genes. Previous studies had shown that approximately 200 genes are upregulated by the treatment of hormone naive chickens with estrogen. As a result of our liver transcriptional profiling, we identified 1,528 genes at 1.5hrs, 1,931 genes at 3hrs, 2,398 genes at 6hrs, 2,356 at 12hrs, and 1,713 genes at 24hrs following estrogen exposure. We determined that these regulated genes include those responsible for the transcription of RNA used to create the gene products that serve as components of VLDL itself or that act in VLDL assembly. These include genes encoding structural proteins, like ApoB, and genes encoding assembly-related proteins. Of the differentially expressed genes as compared to time 0, there were approximately 30% which were unannotated with regards to function limiting conclusions. We hope to determine the function of these genes and to annotate them based on this information.

Thesis (Ph. D.)--University of Missouri--Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 171-188). Also available on the Internet.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1920. / Cover title. Reprinted from American naturalist - Part 1: vol. LII (Feb.-Mar. 1918), Part 2: vol. LV (July-Aug. 1921). Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri--Columbia, 1999. / "December 1999." Typescript. Vita. Includes bibliographical references (leaves 171-188). Also available on the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Auburn University, 2004. / Title from PDF title page (viewed on 06/19/2007). Abstract. Vita. Includes bibliographical references.

Campylobacter is the leading cause of bacterial food-borne diarrhoeal disease in the developed world and a significant cause of infant morbidity and mortality in developing countries. Epidemiological studies implicate poultry as a key source of infection, with up to 80% of human cases being attributable to the avian reservoir. An effective vaccine for broilers is predicted to limit the incidence of human campylobacteriosis. Vaccination of chickens with CjaA, either in recombinant form or vectored in live-attenuated Salmonella, has been reported to significantly reduce caecal colonisation by C. jejuni, with more invasive carriers eliciting greater protection. However, protection remains modest and is slow to develop. I therefore sought to improve such vaccines, first by vectoring codon-optimised CjaA in a licensed avian pathogenic E. coli ΔaroA vaccine. In two independent trials, White Leghorn birds were vaccinated subcutaneously on the day of hatch and 14 days later then challenged with C. jejuni M1 at 28 days post-hatch. No protection was observed despite significant induction of CjaA-specific serum IgY, however, a previously described S. Typhimurium ΔaroA vaccine vectoring CjaA also failed to protect. Owing to the variability observed with live CjaA-based vaccines in these and previous studies, other candidate antigens were sought and evaluated as subunits. Twenty-one candidate C. jejuni antigens were cloned and expressed as glutathione-S-transferase (GST) fusions. Nine of these could be purified in adequate soluble quantities to be tested in vivo. The intervals of vaccination and challenge were as above, with GST alone or GSTCjaA acting as negative and positive controls, respectively. Each antigen was administered subcutaneously in TiterMax Gold® adjuvant at the molar equivalent of the doses of GSTCjaA. Repeated testing of initially promising candidates revealed that, when averaged across three independent trials, GST-SodB and GST-FliD induced statistically significant reductions in caecal colonisation of 1-2 log10 colony-forming units of C. jejuni at 48 and 56 days post-hatch compared to negative controls. Induction of antigen-specific serum IgY was measured by enzyme linked-immunosorbent assays using maltose-binding protein fusions to each antigen. This revealed significant induction of antigen specific serum IgY for the majority of the antigens tested, even when no protection was observed. In the SodB- and FliD-vaccinated groups, the peak of antigen-specific serum IgY was not coincident with the onset of protection and the fold-change in specific IgY levels in individual birds did not correlate with caecal Campylobacter numbers. Furthermore, sera from SodB-vaccinated birds failed to detect SodB in the outer membrane or surface of Campylobacter cells, indicating that SodB-specific antibodies are unlikely to be neutralising. Taken together, these studies identified two novel protective antigens that, with further optimisation, could form part of an anti-Campylobacter vaccine for broilers. However further studies are required to define the nature and consequences of immune responses required for protection.

Avian coccidiosis is caused by the intestinal protozoa Eimeria. The parasite"s site of infection in the intestine is site specific. Eimeria acervulina infects the duodenum, E. maxima the jejunum, and E. tenella the ceca. Lesions in the intestinal mucosa cause reduced feed efficiency and body weight gain in Eimeria-challenged chickens. The growth reduction may be due to changes in expression of digestive enzymes and nutrient transporters in the intestine. The objective of this thesis was to examine the expression of digestive enzymes: APN and SI, peptide and amino acid transporters: Pept1, ASCT1, bo,+AT/rBAT, B0AT, CAT1/2, EAAT3, LAT1 and y+LAT1/2, sugar transporters: GLUT1, GLUT2, GLUT5 and SGLT1, mineral transporter: ZNT1 and an immune factor: LEAP2 in the duodenum, jejunum, ileum and ceca of Eimeria-challenged layers and broilers. Comparisons were made between E. acervulina-challenged layers and broilers and E. acervulina, E. maxima and E. tenella-challenged broilers to examine the effect of chicken breeds and Eimeria species, respectively, on digestive enzymes and nutrient transporter expression. E. acervulina-challenged layers and broilers showed downregulation of APN, bo,+AT/rBAT, B0AT, CAT2, EAAT3, GLUT2, SI, ZNT1 and LEAP2 in the duodenum, but not in the jejunum and ileum. E. acervulina-challenged duodenum, E. maxima-challenged jejunum and E. tenella-challenged ceca samples showed common downregulation of APN, GLUT5 and ZNT1. These results demonstrate that there are common changes in intestinal gene expression in response to E. acervulina in broilers and layers, and common changes in response to challenge by different Eimeria species in broilers. / Master of Science

Phage libraries are a versatile source of recombinant antibody fragments directed against a wide variety of antigens. Recombinant antibodies have the advantage that they can be engineered to improve their binding or other characteristics. A chicken single chain variable fragment (scFv) phage library was panned against the 16 kDa antigen of Mycobacterium tuberculosis. Three phage displayed antibodies were obtained which bound specifically to the antigen. In soluble scFv format, however, they produced low ELISA signals. For this reason they were able to be used as models for antibody engineering. Three mutant sub-libraries were created by random mutagenesis. High stringency panning of the mutant sub-libraries against the target antigen yielded stronger binders which produced ELISA signals of up to eleven times higher than the parent scFvs. An increase in affinity was confirmed by surface plasmon resonance. One mutant scFv with a single amino acid exchange also showed an increase in the yield of scFvs it produced. Upon shortening the linker sequence between the heavy and light chains, size exclusion chromatography showed that multimerisation had occurred. Dimers, trimers and tetramers were formed thus increasing the avidity of the scFvs. Tetramers derived from the unmutated scFv showed the greatest improvement in ELISA binding. To improve expression and purification, an alternate bacterial expression vector with a histidine tag was investigated. For this series of experiments the coding region for a chicken scFv directed against VP7 of bluetongue virus was transferred from the pHEN1 display vector to the pSANG 14-3F vector, which fuses the scFv gene to a bacterial alkaline phosphatase gene. A bi-functional chicken scFv-alkaline phosphatase fusion protein that exhibits both alkaline phosphatase activity and specific antigen binding was expressed in Escherichia coli and purified in a single step via metal affinity chromatography. Furthermore the scFv-AP fusion protein was directly detected in ELISA without the use of secondary detection reagents. This study confirms that the strategies used can efficiently enhance the characteristics of chicken scFvs. / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted