Browsing by Subject "Agriculture"
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Item Genetic Engineering and the Food Supply(2000-12-01) Kennedy, W. Russ; Samuel F. AtkinsonAs food sources high in the trees became inadequate, our predecessors climbed to the ground and through centuries of adaptation learned to stand upright and cultivate plants. Plant cultivation has been practiced for more than ten thousand years with continuous improvements made to crop plants to meet the growing food needs of human domesticated animal populations. Biotechnology has been practiced for thousands of years with fermentations of fruits and grains to make wine and beer and the use of yeast in baking. More recently, advances in molecular biology allow the analysis and manipulation of genetic material to achieve desired changes in the organism. Transgenics or genetic engineering is the process of identifying specific genetic defects or desirable traits and altering an organism’s DNA by addition or deletion of specific DNA sequences. Nearly 100 million acres (40 million hectares) were planted in transgenic crops in 1999. The largest acreages of more than 40 different transgenic crops grown were in cotton, corn, soybean and rapeseed. Fifty-five percent of all cotton, 50% of soybeans, and 33% of corn grown in the U.S. in 1999 were transgenic varieties. The large plantings stem from fairly straightforward manipulations of single genes, such as the transferring to corn and cotton genetic material from the bacterium Bacillus thuringiensis (Bt) which produces an insecticidal toxin or transferring to the soybean, corn, cotton, sugar beets, and canola a gene with resistance to herbicides, such as glyphosate. The American farmer is perceived to be the beneficiary of lowered production costs primarily through better weed and pest control and a reduction in pesticide use with accompanying environmental improvement. Agro-chemical companies, who for the most part have spearheaded research and development of these crops, became involved because they foresaw a declining market for pesticides. Another area of promise widely discussed in the scientific and popular press is the improvement of food quality and composition resulting from genetic engineering. Because plants and plant products provide much of the world’s food supply, it is only fitting that early applications of this technology be in this area. Recent estimates suggest that the market for transgenic seed has already reached several hundred million dollars per year and that more than 15 million hectares (37 million acres) were grown in the U.S. in 1998. Concerns of food risk to the food supply and environment that using transgenic methods present, although not always science based, have some merit and require careful scientific scrutiny.Item Quorum Sensing in Sinorhizobium meliloti(2008-12-01) Patankar, Arati V.; Juan E. Gonzales; Jerry W. Simecka; Stephen O. MathewPatankar, Arati V., Quorum Sensing in Sinorhizobium meliloti. Doctor of Philosophy (Microbiology and Immunology), December 2008, 170 pp., 14 tables, 23 illustrations, bibliography, 212 titles. The overall goal of this study was to elucidate the role of a series of transcriptional regulators and potential signal molecules in the coordination of gene regulation in Sinorhizobium meliloti. The agriculturally important gram-negative soil bacterium S. meliloti, forms a symbiotic association with its host legume, Medicago sativa (alfalfa); thereby serving as a good model for studying host-bacterial interactions. Often, bacteria associated with eukaryotic hosts utilize global gene regulatory systems to coordinate their behavior in order to establish pathogenic or symbiotic associations. Quorum sensing is one such form of bacterial gene regulation which is mediated by signaling molecules and regulatory proteins in a population density dependent manner. In S. meliloti, the process of quorum sensing has been shown to play an important role in the relationship with its host plant. Control of essential processes such as plant nodulation and exopolysaccharide production has been attributed to the Sin/ExpR quorum-sensing system of S. meliloti. Interestingly, S. meliloti contains four additional (SMc04032, SMc00658, Smc00878 and SMc00877) putative quorum-sensing response regulators whose regulatory network was not known. The predicted protein sequences of these genes contain features typical of the LuxR family of proteins i.e., an N-terminal signal binding domain and C-terminal helix-turn-helix DNA biding domain. In order to identify their regulatory role, mutants of the response regulators were constructed and their expression profile was determined by employing genome-wide microarray and real-time PCR expression analysis. Through these analyses, it was determined that the SMc004032 locus controls expression of genes involved in the active methyl cycle, while the SMc00658, SMc00878 and SMc00877 loci control expression of genes from the denitrification of pathway of S. meliloti. Further, through phenotypic studies it was established that SMc04032 impacts stress response adaptation, and effective competition for plant nodulation. This suggests that SMc04032 could play a role in bacterial survival in the soil as well as within the host. The ability to denitrify is highly variable in different strains of S. meliloti. Through growth and enzymatic assays, it was established that the wild-type strain of this study, S. meliloti Rm8530, is a partial dentrifier in which, the capacity to metabolize nitrate is impaired. It was further determined that SMc00658, SMc00878 and SMc0877 modulated nitrite reductase activity under aerobic conditions, implying that these genes are involved in aerobic denitrification and therefor probably play a role in detoxification in S. meliloti. Based on the sequenced-genome analysis, S. meliloti possess homologs of other mediators of quorum sensing, that might be responsible for the synthesis of novel signal molecules. Bioreporter strains and mass spectrometry analysis were employed to identify production of cyclic dipeptides in S. meliloti. These compounds have been previously reported as quorum-sensing signal molecules in several bacteria. The results presented in this study provide a better understanding of S. meliloti’s metabolic and physiological properties and will be fundamental in future studies of bacterial interaction with its host and survival within its ecological niche.Item Scientific Proceedings of the Royal Dublin Society; AN EXAMPLE OF THE MULTIPLE COUPLINGOF MENDELIAN FACTORS .(The Royal Dublin Society; Williams and Norgate, 1913-03-01) Wilson, JamesItem Scientific Proceedings of the Royal Dublin Society; Inter-Alternative as Opposed to Coupled Mendelian Factors: A Solution of the Agouti-Black Colour in Rabbits(The Royal Dublin Society; Williams and Norgate, 1915-01-01) Wilson, JamesItem Scientific Proceedings of the Royal Dublin Society; THE INHERITANCE OF COAT COLOUR IN HORSES.(The Royal Dublin Society; Williams and Norgate, 1910-04-01) Wilson, JamesItem The Mechanism of Agriculture and Health Exploration of Links Between Agricultural Practice and Human Nutrition in Rural China(2008-05-01) Campos-Bower, Monica Haydee; Nuha Lackan; Robert Kaman; Sejong BaeCampos-Bower, Monica Haydee, The mechanism of agriculture and health-Exploration of links between agricultural practice and human nutrition in rural China Doctor of Public Health (Health Management and Policy), May 2008, 73 pp, 9 Tables, 5 Figures, bibliography, 23 titles. Health consequences of nutritional deficiencies remain a concern for more than half of the global population. Agriculture improvement has helped to alleviate nutritional deficiencies, especially among the rural developing world, where populations are more susceptible. In China, approximately 80% of the population lives in rural areas with close to 40% suffering from at least one nutrient deficiency. Current agricultural development projects in China are geared toward enhancing crop nutrition, but more research is needed to determine the relationship between food practices, agricultural diversity and the nutritional health in rural areas. The purpose of this research was to evaluate the direct relationship of agriculture on human health through assessment of agricultural practices and agricultural policy on human health symptoms in rural populations in China. A comparative study was performed on data from the University of North Carolina Population Center-China Health and Nutrition Survey (CHNS) and a case study based on field research in western China. The study demonstrated relationships between agricultural practices with human health symptoms. In addition, agricultural and environmental policies adopted in rural areas did impact ability to engage in agricultural practices as well as diet and human activity among rural households. Future agricultural and environmental policies should consider repercussions of policy effects on community social infrastructure, economy and health and create measures to address these issues.Item The Relationship Between Atrazine Exposure and Breast and Ovarian Cancer Incidence Rates in Texas Agricultural Statistical Districts(2006-05-01) Hull, Kimberly M.; Terrance Gratton; Eric Johnson; Sejong BaeHull, Kimberly M., The Relationship Between Atrazine Exposure and Breast and Ovarian Cancer Incidence Rates in Texas Agricultural Statistical Districts. Masters of Public Health (Environmental Health), May 2006, 95pp., 16 tables, 7 illustrations, reference, 74 titles. The herbicide, atrazine, is suspected to cause cancer primarily through drinking water. This ecological study analyzed relationships between potential atrazine exposures and female breast and ovarian cancer incidence rates in Texas Agricultural Statistical Districts. Atrazine exposures are: atrazine usage, rural population, and public water systems. Study results indicate an inverse relationship between four atrazine exposures and breast and ovarian cancer incidence rates (county level). There is a positive relationship between surface water systems and ovarian cancer incidences rates (county level). There also is an inverse relationship between one atrazine usage index and ovarian cancer incidence rates (district level). Study results are similar to other atrazine and cancer studies; correlations prevent statements of causal inference.