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Soyabean meal (SBM), the major protein source in feeds in sub-Saharan Africa, is in short supply. The shortage is a major constraint to intensified animal production to meet increased demand hence the dire need to search for alternatives. Kigelia africana, Mumisops zeyheri, Terminalia sericea and Ximenia caffra are indigenous fruit bearing trees (IFBTs) whose seeds’ potential as alternative protein sources in feeds were evaluated. The evaluation consisted of an initial physico-chemical characterization of the seeds followed by determining in vitro the safety of seed oils on cell lines. Based on the physico-chemical and in vitro evaluation, the most suitable seed was selected, defatted and its meal used as a dietary substitute to SBM in the in vivo trials using adult and weanling male Sprague Dawley rats. The T. sericea seed yield was not viable. Chemically K. africana and X. caffra seed demonstrated potential as protein sources in feeds. M. zeyheri seed demonstrated potential as an energy source. The IFBTs seeds oil yield surpassed that of some traditional oilseed crops. Oleic and linoleic acid were the major fatty acids contained in the oils. In vitro, K. africana, M. zeyheri and X. caffra seed oils suppressed Caco-2 and HEK-293 cell proliferation without causing cell death. X. caffra seed, deemed the most suitable, was defatted and its seed meal used in the in vivo trials. In mature rats, dietary substitution of SBM with the defatted X. caffra seed meal did not affect (P > 0.05) dry matter intake, apparent digestibility of nutrients and nitrogen absorption and retention. In weanling rats, the defatted X. caffra seed meal had no effect on termination (body mass at the end of the feeding trial) and empty carcass mass and linear growth of the rats. Metabolic substrate storage, fasting blood glucose concentration and the general health profile of the growing rats were not altered by dietary X. caffra seed meal. The defatted X. caffra seed meal increased the mass of the stomach and small intestine (P = 0.0071; P = 0.0001) of rats on the test diet where a 100% dietary crude protein (CP) from SBM was substituted by CP from the defatted X. caffra seed meal. Defatted X. caffra seed meal could substitute SBM in rat and possibly monogastrics feeds without compromising digestibility, nitrogen balance, growth and general health.

Further in vivo and in vitro studies using the truncated OsRMR1 proteins from the culture media of transgenic BY-2 cells demonstrated that OsRMR1 functioned as a receptor in transporting vicilin-like storage proteins via specific interaction with their vacuolar sorting determinants. Taken together, the OsRMR1 is a sorting receptor for the PSV pathway that defines a novel organelle as PVC for PSV in rice. / Receptor-mediated protein sorting is one of the mechanisms for transporting soluble proteins to the protein storage vacuoles (PSVs) in plant cells. Members of vacuolar sorting receptor (VSR) family proteins and receptor homology region-transmembrane domain-RING-H2 (RMR) family proteins have been shown to function in mediating the transport of storage proteins to PSVs in plants. However, no prevacuolar compartment (PVC) for the PSV pathway has been identified. In this study, I used a rice RMR protein (OsRMR1) as a probe to study the PSV pathway in rice. Using confocal immunofluorescent and immunogold electron microscopy (EM) with specific OsRMR1 antibodies, I have identified a novel organelle as a PVC for the PSV pathway, because OsRMR1 antibodies labeled the Golgi apparatus, trans-Golgi network (TGN) and the novel organelle in both rice cultured cells and developing rice seeds, as well as the protein body Type II (PBII) in developing rice seeds. This novel organelle is morphologically distinct from the lytic PVC or multivesicular body (MVB). / Shen, Yun. / "May 2008." / Adviser: Liwen Jiang. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1428. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 124-139). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

No description available.

<p>Plant natriuretic peptides (PNPs) are a novel class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. Natriuretic peptides were first identified in vertebrates where they play a role in the regulation of salt and water balance. Subsequent experimental investigations have identified the presence of a natriuretic peptide hormone system in plants. While PNPs have been implicated in various physiological responses such as stomatal guard cell movements and regulation of net water uptake, its biological role has remained elusive. Here we have used co-expression and promoter content analysis tools to understand the biological role of the Arabidopsis thaliana PNP (AtPNP-A). The analysis of AtPNP-A and its co-expressed genes revealed that genes annotated as part of the systemic acquired resistance (SAR) pathway were over-represented, thus suggesting that AtPNP-A may function as a component of plant defense responses and specifically, SAR. The results further show that AtPNP-A shares many characteristics with pathogenesis related (PR) proteins in that its transcription is strongly induced in response to pathogen challenges, thus implying a newly described role for AtPNP-A in pathogen attack. Additional tissue expression analysis also indicated distinct localization of PNP activity in sepals and transcriptional meta-analysis showed that AtPNP-A may play a role in starch breakdown. Therefore, together with the finding that AtPNP-A plays a role in regulating phloem transport, we also hypothesize that AtPNP-A may play a role in phloem unloading in sepals to assist processes such as seed formation in plants. In plants, the second messenger, guanosine 3&rsquo / ,5&rsquo / -cyclic monophosphate (cGMP) mediates a whole range of important processes including salinity tolerance, disease resistance, drought tolerance and responses to light. Since PNPs regulate water and salt homeostasis via a cGMP-dependent signaling pathways, it is thus important to analyse the transcriptome induced by the second messenger (cGMP) in Arabidopsis thaliana to give a better understanding of its mechanism of action. This study was also supplemented by the analysis of the gibberellic acid (GA) dependent transcriptome, since cGMP also plays a role its transcription pathway. This data analysis, together with promoter content investigation, revealed that genes upregulated after cGMP treatment and down-regulated in the GA insensitive mutant (ga1-3) were enriched with a GA response element (GARE), while no GARE enrichment were observed in genes up-regulated in the ga1-3 mutant. These findings suggest that GARE is indicative of GA-induced and cGMP-dependent transcriptional up-regulation. Gene ontology analysis confirmed previous reports that cGMP is involved in ion homeostasis and indicated that the transcriptional cGMP response is bi-polar in the sense that both genes up- and down-regulated in response to cGMP is involved in cation transport. Additionally, ab initio analysis of genes transcriptionally dependent on cGMP identified CHX8 as a hub gene and promoter content of CHX8 co-expressed genes show enrichment of the GARE motif. The fact that CHX8 has its highest expression levels during male gametogenesis and pollen tube growth, together with our findings, suggest that GA-induced and cGMP- dependent genes may play a key role in ion and water homeostasis in the male gametophyte. Finally, we propose that the type of analysis undertaken here can yield new insights into gene regulation networks and inform experimental strategies to unravel complex transcription regulatory systems under different developmental and stimulus specific conditions.</p>

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 16, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Science, Department of Agricultural, Food and Nutritional Sciences, University of Alberta." Includes bibliographical references.

The effects of extracts from purple nutsedge tubers were determined on the germination, growth, root leakage, water status, and photosynthesis of an Upland cotton, DPL 5415, and a Pima cotton, Pima S-7. Tubers extracts inhibited secondary root growth of seedlings more than primary root growth. At 500 ppmw, primary root growth was inhibited 44 percent whereas inhibition of secondary root growth was 64 percent. Non-polar extracts were more inhibitory to growth than polar extracts. Cotton plants grown in soil treated with hexane extracts of tubers containing non-polar allelopathic substances also lost electrolytes from their roots indicating an effect on root function. The effects on root function resulted in perturbations to the capacity of the plants to maintain efficient water status. At 250 ppmw of the hexane extract, the plant water potential, the leaf water content, and the leaf osmotic potential decreased from -0.7 to -1.3 MPa, from 89 to 79 percent, and from -0.8 to -1.0 MPa, respectively. In addition, the photosynthetic capacity of cotton was decreased 50 percent in both cotton cultivars in the second and third day after transplanting to soil treated with 62 ppmw of the hexane extracts. Leaf dehydration to below 70 percent relative water content and a reduction of quantum yield was detected in DPL 5415 at 125 ppmw of the hexane extracts. However, Pima S-7 was capable of tolerating higher levels of dehydration and did not show the reduction of quantum yield. Leaf expansion and epicotyl growth were also inhibited by 30 and 37 percent, respectively, by the hexane extracts at 250 ppmw. Purple nutsedge tubers released volatile substances that inhibited growth when trapped and tested on cotton seedlings, and caused root leakage. GC analyses showed that both the hexane extracts of purple nutsedge tubers and the volatile compounds released from the tubers contained substances with retention times that are characteristic of sesquiterpenes. These results demonstrate that purple nutsedge tubers contain allelopathic substances capable of inhibiting the growth of cotton by interfering with membranes of root cells, disrupting water status, and affecting photosynthesis.

Previous studies have shown that transcriptional differences in the orf224-atp6 mitochondrial gene region are correlated with fertility restoration of the pol CMS trait by the dominant nuclear Rfp gene in Brassica napus. Recently, the recessive rfp allele, or a tightly linked gene, was found to act as a dominant gene, designated Mmt, in controlling the production of additional, smaller transcripts of two other mitochondrial loci. The results presented in this thesis reveal that Mmt-specific transcripts lack sequences found at the $5 sp prime$ end of the full-length transcripts of these loci and contain a common sequence, UUGUGG, which maps immediately downstream of their $5 sp prime$ termini. A similar sequence, UUGUUG, is found within orf224 downstream of the major Rfp-specific $5 sp prime$ transcript terminus; these hexanucleotide sequences may serve as recognition motifs in the generation of Mmt- and Rfp-specific transcripts. These results suggest that Rfp/Mmt is a novel nuclear locus affecting the expression of multiple mitochondrial gene regions, with different alleles or haplotypes affecting different mitochondrial genes.

<p>Plant natriuretic peptides (PNPs) are a novel class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. Natriuretic peptides were first identified in vertebrates where they play a role in the regulation of salt and water balance. Subsequent experimental investigations have identified the presence of a natriuretic peptide hormone system in plants. While PNPs have been implicated in various physiological responses such as stomatal guard cell movements and regulation of net water uptake, its biological role has remained elusive. Here we have used co-expression and promoter content analysis tools to understand the biological role of the Arabidopsis thaliana PNP (AtPNP-A). The analysis of AtPNP-A and its co-expressed genes revealed that genes annotated as part of the systemic acquired resistance (SAR) pathway were over-represented, thus suggesting that AtPNP-A may function as a component of plant defense responses and specifically, SAR. The results further show that AtPNP-A shares many characteristics with pathogenesis related (PR) proteins in that its transcription is strongly induced in response to pathogen challenges, thus implying a newly described role for AtPNP-A in pathogen attack. Additional tissue expression analysis also indicated distinct localization of PNP activity in sepals and transcriptional meta-analysis showed that AtPNP-A may play a role in starch breakdown. Therefore, together with the finding that AtPNP-A plays a role in regulating phloem transport, we also hypothesize that AtPNP-A may play a role in phloem unloading in sepals to assist processes such as seed formation in plants. In plants, the second messenger, guanosine 3&rsquo / ,5&rsquo / -cyclic monophosphate (cGMP) mediates a whole range of important processes including salinity tolerance, disease resistance, drought tolerance and responses to light. Since PNPs regulate water and salt homeostasis via a cGMP-dependent signaling pathways, it is thus important to analyse the transcriptome induced by the second messenger (cGMP) in Arabidopsis thaliana to give a better understanding of its mechanism of action. This study was also supplemented by the analysis of the gibberellic acid (GA) dependent transcriptome, since cGMP also plays a role its transcription pathway. This data analysis, together with promoter content investigation, revealed that genes upregulated after cGMP treatment and down-regulated in the GA insensitive mutant (ga1-3) were enriched with a GA response element (GARE), while no GARE enrichment were observed in genes up-regulated in the ga1-3 mutant. These findings suggest that GARE is indicative of GA-induced and cGMP-dependent transcriptional up-regulation. Gene ontology analysis confirmed previous reports that cGMP is involved in ion homeostasis and indicated that the transcriptional cGMP response is bi-polar in the sense that both genes up- and down-regulated in response to cGMP is involved in cation transport. Additionally, ab initio analysis of genes transcriptionally dependent on cGMP identified CHX8 as a hub gene and promoter content of CHX8 co-expressed genes show enrichment of the GARE motif. The fact that CHX8 has its highest expression levels during male gametogenesis and pollen tube growth, together with our findings, suggest that GA-induced and cGMP- dependent genes may play a key role in ion and water homeostasis in the male gametophyte. Finally, we propose that the type of analysis undertaken here can yield new insights into gene regulation networks and inform experimental strategies to unravel complex transcription regulatory systems under different developmental and stimulus specific conditions.</p>

Thesis (M. Sc.)--University of Stellenbosch, 2008. / Includes bibliographical references. Also available via the Internet.