No description available.

Salmonellosis is one of the most important bacterial food borne illnesses worldwide. Among the many Salmonella serotypes, Typhimurium is the most commonly implicated serotype in human disease in the United States. A major source of infection for humans is consumption of chicken or egg products that have been contaminated with S. Typhimurium. The breadth of knowledge regarding colonization and persistence factors in the chicken is small when compared to our knowledge of factors that are important for these processes in other species used in Salmonella research, such as cattle and mice. Defining the factors important for these processes in the chick is the first step in decreasing the transmission of Salmonella between animal and human hosts. In this work, we developed a chicken model to identify and study intestinal colonization and persistence factors of Salmonella enterica serovar Typhimurium. We studied the degree of enteric and systemic colonization of wild type S. Typhimurium ATCC14028, one of the most widely studied Typhimurium isolates, in White Leghorn chicks and in Salmonella-resistant CBA/J mice during infection. Furthermore, we determined the distribution of wild type S. Typhimurium and a SPI-1 mutant (invA) during competitive infection in the cecum of 1-week-old chicks and 8-week-old mice. Cell associated, intracellular and luminal distributions of these strains in the cecum were analyzed as total counts in each compartment and also as a competitive index. Localization of S. Typhimurium ATCC14028 and the role of SPI-1 in colonization are well studied in murine models of infection, but comparative infection in chicks with the same strain has not been undertaken previously. We show that the cecal contents are the major site for recovery of S. Typhimurium in the cecum of 1-week-old chicks and Salmonella-resistant mice. We also show that while SPI-1 is important for successful infection in the murine model, it is important only for cell association in the cecum of 1-week-old chicks. Finally, we found that in chicks infected at 1 week of age, bacterial counts in the feces do not reflect those seen in the cecum as they do in mice.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 93-120).

Prostanoid receptors (PG-Rs: prostaglandin D, E, F, prostacyclin and thromboxane receptors (DP, EP1-4, FP, IP and TP)) are known to mediate a diverse range of biological responses, such as cardiovascular homeostasis, nociception and reproduction, via binding to their respective ligands belonging to the five classes of prostanoids (PGs: class D, E, F, I and thromboxane). The majority of these findings were reported in mammals, and despite suggestive evidence provided by previous pharmacological and physiological studies in non-mammalian vertebrates, investigations on the mechanisms behind actions of PGs were impeded by the limited information on their receptors. In the present study, the full-length cDNAs of chicken (c-) and zebrafish (z-) prostanoid receptors – cEP3, cFPs, zEP1s and zFP – were identified from respective adult ovaries and their tissue distribution examined by RT-PCR. A novel middle-truncated splice variant, cFPb, which lacks 107 amino acids between transmembrane domains 4 and 6 but otherwise identical to cFPa was first identified. Three isoforms of zEP1 – zEP1a, zEP1b, zEP1c – were found, which might have subfunctionalized in their ligand binding and G protein coupling specificity, in addition to differential tissue distribution. Using various luciferase reporter systems (pGL3-CRE, pGL-NFAT-RE, pGL4-SRE), all the cloned receptors, except cFPb, were shown to potentially couple to intracellular cAMP, Ca2+, and/or MAPK signaling pathways. Owing to the proposed roles of PGs and its potential regulation by and/or on EGFR ligands and gonadotropins in mammals and chicken, genes involved in regulation of PG functions at various levels, including biosynthesis (COX1, COX2, mPGES1, mPGES2 and cPGES), availability (PGT) and signaling (cEPs and cFPs), were also characterized in granulosa cells during hen follicular development. Lastly, using our experimental data and systematic sequence retrieval from available databases, the PG receptor cascades from representative vertebrate species were pooled and analysed using phylogenetic analyses and synteny studies. Three putative clusters (IP-like, EP4-like and EP1-like cluster) were found in lamprey genome; meanwhile, only one PG-R-like cluster was identified from the Cephalochordate lancelet (amphioxus) genome. This concurs with the 1-2-4 rule proposed in first round/second round (1R/2R) whole genome duplication in which the missing lamprey cluster was presumably lost secondarily. With support from conserved orthologs-localization, the four PG-R paralogs (proto-EP4, proto-IP/EP2/DP, proto-TP/FP/EP1 & putative proto-EP3 genes) in the ancestral vertebrates might have further diversified via either localized- (e.g. EP2 and DP) or chromosomal segmental duplication (e.g. EP1, FP and TP) which resulted in the present array of vertebrate PGRs. Additional paralogs (e.g. EP1 and EP4) were identified from fishes, by which molecular dating coincide with and hint of their origins whence the ancient fishspecific whole genome duplication (3R) occurred ~350 million years ago. The present study offers the first glimpse and a better understanding of the roles of the PG-Rs and presents a higher resolution to the evolutionary history of each PG-R family member, consolidating that particular care has to be taken when studying non-mammalian PG-R functions in which some members are absent or present in multiples and propel the investigation of adaptational changes in the coding sequence during evolution of vertebrate PG-Rs. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

No description available.

Thesis (doctoral)--University of Tampere, 1987. / Includes bibliographical references (p. 42-56).

Thesis (Ph. D.)--University of Chicago, Committee on Neurobioloy, March 2001. / Includes bibliographical references. Also available on the Internet.

No description available.

The results secured from the series of tests appear to be conclusive enough to be used as a basis for certain recommendations. / Master of Science

An attempt was made to study the effects of a tranquilizer (metoserpate hydrochloride), specifically designed for poultry, on the neonatal approach response of domestic chicks. Acquisition of this response was accomplished in a straight alley on birds ranging in age from 24 to 120 hours old. Testing of this response was done when all birds were 144 hours old under a no-drug condition. At 168 hours of age all subjects were subjected to extinction procedures. The strength of the response was measured in terms of latency to start as well as time spent traversing the alley. Resistance to extinction was measured in terms of the latencies mentioned above as well as number of trials to extinction. The results of the present study show a peak in imprinting susceptibility between 72 and 96 hours after hatching. The tranquilizer had a traditional interference effect except for those birds exposed on Day 3 while the injection control procedure had an enhancement effect on birds treated on Days 4 and 5. In addition, there were no differences observed during extinction between groups. / Master of Science