<p>Studies in the ankyrin-B+/- mouse reveal that ankyrin-B deficiency is associated with both the benefits of enhanced cardiac contractility and the costs of arrhythmia, early senescence, reduced lifespan, and impaired glucose tolerance. This constellation of traits is known as ankyrin-B syndrome, which may have important implications for humans possessing functional ankyrin-B mutations. We found that ankyrin-B variants are surprisingly common, ranging from 2 percent of European individuals to 8 percent in individuals from West Africa. Furthermore, by studying of the metabolic phenotype associated with ankyrin-B mouse, we have uncovered a major new dimension to ankyrin-B syndrome, a link between ankyrin-B and parasympathetic control of insulin secretion. Stimulation of pancreatic beta cells by acetylcholine augments glucose-stimulated insulin secretion by inducing inositol-trisphosphate receptor (InsP3R)-mediated Ca2+ release. We report that ankyrin-B is also enriched in pancreatic beta cells. Ankyrin-B-deficient islets display impaired potentiation of insulin secretion by the muscarinic agonist carbachol, blunted carbachol-mediated intracellular Ca2+- release, and reduced InsP3R stability. Ankyrin-B(+/-) mice also display postprandial hyperglycemia, consistent with impaired parasympathetic potentiation of glucose-stimulated insulin secretion. R1788W mutation of ankyrin-B impairs its function in pancreatic islets and associates with type 2 diabetes in Caucasians and Hispanics. Finally, we have generated knockin mice corresponding to the R1788W and L1622I mutations. Functional characterization of these animals will allow us to better understand the relationship between human ankyrin-B variants and ankyrin-B syndrome.</p> / Dissertation

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With the introduction of antibiotics in animal feed becoming less popular, the agricultural industry has begun a shift towards the use of probiotics in animal feed. Since there is no current method to evaluate the risks of using genetically modified probiotics in animal feed. The goal of this project was to create a genetically modified model organism for risk assessment. The genetic marker for that was chosen was GFP that was to be expressed on the surface of the cell. The fluorescent properties allow for visualisation of the genetically modified bacteria and the surface expression would allow for the easy capture and recovery of the bacteria for culturing and cell counts. Genome wide screens were performed using the CW PRED algorithm to locate proteins with LPXTG motif for cell wall anchoring. 16 hypothetical proteins were detected and 6 were selected as candidates for possible surface display of GFP. Of these candidates, the novel L. casei protein LSEI_2320 was found to be expressed at the mRNA during early growth by RT PCR and at then protein level during stationary phase with western blot. This LPXTG protein was found at the surface of L. casei ATCC334 during stationary phase and late stationary phase with immunofluorescence microscopy. A genetically modified L. casei ATCC334 was constructed using the surface protein LSEI_2320 locus as a region for recombination with the pRV300 suicide plasmid. Genetic modification of the locus by the insertion of a GFP reporter region just before the predicted signal peptide site resulted in the abrogation of the expression of LSEI_2320 from the cell surface at the late stationary phase. It appears that this particular gene is not necessary to cell survival even though it is abundantly expressed on the cell surface and can be used as a location for genetic modification in L. casei ATCC334.

With the introduction of antibiotics in animal feed becoming less popular, the agricultural industry has begun a shift towards the use of probiotics in animal feed. Since there is no current method to evaluate the risks of using genetically modified probiotics in animal feed. The goal of this project was to create a genetically modified model organism for risk assessment. The genetic marker for that was chosen was GFP that was to be expressed on the surface of the cell. The fluorescent properties allow for visualisation of the genetically modified bacteria and the surface expression would allow for the easy capture and recovery of the bacteria for culturing and cell counts. Genome wide screens were performed using the CW PRED algorithm to locate proteins with LPXTG motif for cell wall anchoring. 16 hypothetical proteins were detected and 6 were selected as candidates for possible surface display of GFP. Of these candidates, the novel L. casei protein LSEI_2320 was found to be expressed at the mRNA during early growth by RT PCR and at then protein level during stationary phase with western blot. This LPXTG protein was found at the surface of L. casei ATCC334 during stationary phase and late stationary phase with immunofluorescence microscopy. A genetically modified L. casei ATCC334 was constructed using the surface protein LSEI_2320 locus as a region for recombination with the pRV300 suicide plasmid. Genetic modification of the locus by the insertion of a GFP reporter region just before the predicted signal peptide site resulted in the abrogation of the expression of LSEI_2320 from the cell surface at the late stationary phase. It appears that this particular gene is not necessary to cell survival even though it is abundantly expressed on the cell surface and can be used as a location for genetic modification in L. casei ATCC334.