Thesis (Ph.D.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 169-215). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NQ99230

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Jan. 11, 2010). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Food Science and Technology, Department of Agricultural, Food and Nutritional Science, University of Alberta." Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2003. / Includes bibliographical references (leaves 168-174).

Thesis (M.Inst.Agrar. (Animal Production (Animal and Wildlife Sciences)) -- University of Pretoria, 2009. / Abstract in English. Includes bibliographical references.

 Galanin is a multi-functional neuropeptide with widespread distribution in the central and peripheral nervous systems of different species. It exerts a broad spectrum of physiological functions through the interactions with three galanin receptor subtypes namely the GalR1, GalR2 and GalR3, which have only been identified in mammals. In contrast to the extensive studies in mammals, little is known about the structures and functions of galanin and its receptors in avian species. In the present study, a total of nine chicken cDNAs including four galanin prepropeptide transcript variants (cGal -v1 to -v4), the three known galanin receptor subtypes (cGalR1, cGalR2 and cGalR3), and two novel galanin receptor subtypes designated the GalR1-like (cGalR1-L) and GalR2-like (cGalR2-L), were cloned from the brain and intestine tissues, respectively. The four cGal transcript variants encode precursor peptides of 117, 141, 88 and 150 residues, respectively, which eventually produce two isoforms of mature chicken galanin peptide, the cGal (1-29) and a novel cGal (1-53), through proteolytic processing of the galanin prepropeptide. The five isolated cGalR cDNAs encode receptor proteins of 357-to 405-residue-long, which share amino acid sequence identities ranged from 50% to 86% with their corresponding mammalian counterparts. From RT-PCR analysis, the cGal and cGalRs (except for cGalR3) showed diverse mRNA expression profiles among the adult chicken tissues examined including different regions of the oviduct. Using luciferase reporter systems, it was demonstrated that all the five cGalRs, transiently transfected in Chinese hamster ovary (CHO) cells, were functionally and differentially coupled to Gs, Gi or Gq protein signalling pathways upon the activations of chicken galanin peptides cGal (1-29), cGal (1-53) and human galanin-like peptide hGALP (1-60), with distinct potencies. The newly identified cGalR1-L and cGalR2-L share similarities with cGalR1 and cGalR2, respectively, in terms of the sequence homology, exon/intron organization and signalling pathways, thus suggesting an early gene duplication event in vertebrate evolution in the galanin receptor family. On the other hand, the failure of identifying GalR1-L and GalR2-L genes in mammalian species suggests their deletion events in the mammalian lineage, which are supported by the comparative synteny analyses of galanin receptor family between the human, chicken, zebrafish and Xenopus genomes. Together, these findings establish a molecular basis to elucidate the physiological roles of galanin and its receptors in birds. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

Not available / text

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

No description available.

Antibiotics have been included in poultry feeds to improve growth performance. However, it is a concern that pathogens have become increasingly resistant to antibiotics. Lysozyme is a potential replacement for antibiotics. A trial with or without heat stress was conducted to investigate different inclusion levels (0, 50, 100 and 200ppm) of lysozyme on broiler chickens. Another two trials were conducted using clean or used litter to determine the effect of 100 ppm lysozyme on broiler chickens in each period of the growth cycle. Birds fed the 50 ppm treatment had heavier weight than birds fed the 200 ppm treatment on day 35 (P<0.05). When used litter was provided, feeding lysozyme to birds from days 5-14 and throughout the trial reduced the number of E. coli in the ileum compared with feeding antibiotic to birds (P<0.05). Dietary lysozyme positively influences bacterial numbers in the gastrointestinal tract of broiler chickens.

Changes in the levels of expression of the prolactin receptor (PRLR) mRNA in the pituitary gland, hypothalamus, liver, pancreas, kidney and gonad from embryonic day (ED) 15 and ED21 to 1 day post-hatch, respectively, in chickens and turkeys were measured by real-time PCR. In both species, PRLR mRNA increased from low levels during the last week of ED to reach maxima at the peri-hatch period. Similarly, circulating levels of prolactin (PRL) also increased during this interval and were correlated with the observed increases in tissue content of PRLR mRNA. This suggested that PRL was up-regulating its own receptor during late embryogenesis. In support of this, in vitro stimulation of the pituitary gland of turkeys with VIP on ED24 resulted in a 4 fold and 3 fold increase in PRL and PRLR, respectively. Stimulation with VIP of either the hypothalamus or gonad had no effect on either levels of the PRLR transcript. This suggests that VIP acts indirectly through increased PRL to upregulate the number of receptors. In order to investigate the transcription of genes that may be induced/suppressed by PRL, suppressive subtractive hybridization (SSH) libraries from control or VIP stimulated ED24 turkey pituitary glands were constructed. Stimulation with VIP resulted in a 5.7 and 2.8 fold increase in media and pituitary content of PRL, respectively. The changes in PRL were consistent with endogenous levels of PRL observed just prior to hatch. Following sequence analysis of random clones (n=96) from each library, a total of 145 non-redundant putative genes were obtained. About 51% of the putative genes have as yet no assigned function, whereas, 15% were housekeeping genes and 34% had known functions within various pathways. Real-time PCR was used to confirm the differential expression of 21 of these genes in VIP treated and control pituitaries. Since the majority of these genes were expressed at levels consistent with the direction of subtraction, these data suggest that these libraries may be useful to study the direct and indirect effects of increasing levels of PRL on anterior pituitary function at about the time of hatch.