A Mathematical Model for Glucose-Oxygen Kinectics and Cell-Mediated Response in Prostate Cancer Cells of Type II Diabetes
Mathematical models offer a foundation to gain valuable insight in the development and growth of tumor-immune dynamics. I present a new mathematical model that will describe prostate tumor growth in Type II diabetic patients. Additionally, I will offer a mathematical model that will describe immune response, focusing on the role of T-lymphocytes. Finally, I will propose a model that will describe tumor-immune interactions. Each model uses a system of differential equations. Growth rates are determined, under intrinsic Glucose-Oxygen environments. Parameter estimates and mathematical model validations employ published human studies. The model will attempt to provide an adequate first step toward the understanding of cancer dynamics influenced by type II diabetes.
Dept of Biology, Dept of Mathematics, Columbus State University, Columbus, GA
151 • Linda A. Major, Roger A. Sauterer
Histone Binding to Mitochondria in Plants
The genome is continuously exposed to DNA damaging agents that activate the DNA damage response to either repair the DNA or induce apoptosis. During the early DNA damage response, the chromatin compaction around damaged sites is relaxed through specific core histone modifications and displacement of the linker histone H1. In mammalian cells, studies suggest that displaced histones enter the cytoplasm and bind to mitochondria, leading to the permeabilization of the inner and outer mitochondria membranes. This event triggers the release of pro-apoptotic proteins, including cytochrome C, from the mitochondrial intermembrane space to the cytosol where they activate caspases and endonucleases that initiates apoptosis. We investigated whether this mechanism occurs in plants as well. Our preliminary results indicate that histone proteins bind to mitochondria and induce mitochondrial membrane permeabilization in plants. We isolated mitochondria and histone fractions from store-bought cauliflower; then a histone-enriched fraction was added to a mitochondria-enriched fraction, incubated, and examined by Western Blotting against histone H3 and cytochrome C. The results show H3 histones in the mitochondrial pellet but not in the supernatant of the experimental sample, cytochrome C in the pellets of the control and experimental sample, and cytochrome C in the supernatant of the expermental sample but not in the control. The results of this study suggest that histone proteins bind to mitochondria affecting the release of cytochrome C from the intermembrane space of the mitochondria and suggest that the interactions between mitochondria and histones may be broadly conserved across eukaryotes.
Plant Cell Nuclear, Mitochondrial and Chloroplast Isolation: Procedures and Pitfalls
Organelle purification from plant cells is much more challenging than from animal cells due to the presence of cell walls, vacuoles and often relatively low organelle concentrations and each plant tissue is different. We describe suggested procedures for fractionating fairly clean mitochondria, chloroplasts and nuclei from plant cells. Plant tissue can be treated with Viscozyme to obtain protoplasts, but yields are low and intact cells contaminate the samples. Grinding soft leaves in a blender or with a mortar and pestle works best. Tissues with small cells or thick cell walls require empirically determined blending speeds and time. Differential centrifugation followed by Percoll step gradient centrifugation works best to fractionate organelles. Fairly pure chloroplasts are easily obtained by Percoll gradient centrifugation from soft leaves such as spinach. Nuclei are best obtained using chloroplast-free tissues such as cauliflower, as chloroplasts contaminate nuclei fractions on Percoll gradients. Triton differential lysis procedures result in contamination of nuclei by chloroplasts and other organelles. Mitochondria are best obtained by low-speed centrifugation to remove cells, nuclei and large organelles, followed by high-speed centrifugation of the supernatant and Percoll gradient centrifugation of the pellet. In all cases, the exact Percoll concentration for each layer may differ substantially from published procedures depending on tissue type used, age of tissue, and plant species and must be determined empirically. Both plant material amount and the volume of each Percoll gradient step is critical to get sharp bands at the gradient interfaces rather than diffuse bands in a given Percoll layer.
Dept of Biology, Jacksonville State University, Jacksonville, Alabama
153 • Daniel W. Konzman, Linda Niedziela
The Effect of Pentylenetetrazol-Induced Seizure and the Anti-Epileptic Drug Phenytoin on Learning in Danio rerio
Impairments of cognitive function can be caused by both epileptic seizures and anti-epileptic drugs, complicating the management of epileptic disorders. The present study investigated the cognitive impairments due to seizures to those caused by the anti-epileptic drug phenytoin. Adult zebrafish (Danio rerio) will be used as the model system, as they have been shown to be reliable model systems for epilepsy as well as simple learning and conditioning. Learning through operant conditioning in a T-maze was used to measure cognitive impairment. Seizures will be kindled using pentlyenetetrazol (PTZ), a compound that has been established for its utility in seizure research in adult zebrafish. Three chemical treatment groups were tested to compare the effects of seizure with those of the phenytoin and their interaction: PTZ alone, phenytoin alone, PTZ with phenytoin pretreatment, and an untreated control. Each fish was conditioned over 16 trials in a T-maze using positive punishment. Learning was assessed primarily by the number of trials it took each fish to reach a total of three correct responses. Results showed learning speed was significantly (p<0.01) reduced for the PTZ only condition and the doubly-treated condition as compared to control. A trend toward increased impairment was seen when fish received the combination treatment compared to the PTZ only group. These results indicate that phenytoin does not ameliorate the cognitive impairment associated with seizures, as was expected based on similar studies using different anti-epileptic compounds. The observed effect poses a potential problem for those managing their epilepsy with phenytoin and warrants further investigation.
