Division II

Abstracts Submitted: Division II - Graduate students (1-2 years) - Natural Sciences & Mathematics


REGULATION OF DIAPAUSE BY GENES IN THE INSULIN PATHWAY

Andrew B. Barker, Dr. Hugh Miller III, and Dr. Karl Joplin, Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614.

Diapause is a programmed developmental arrest triggered by external events that allows insects to survive their surroundings during harsh environmental conditions. Diapausing insects have been shown to be in a state of cellular arrest, therefore insects during diapause are considered to be ageless. Experimentation using the model organism Caenorhabditis elegans has linked a diapause-like dauer larvae formation to the aging pathway through the insulin receptor pathway. Knockouts or down-regulations within the insulin pathway induce a cellular arrest similar to that of diapause, thus, linking the insulin pathway to the diapause state. It is a working hypothesis that the diapause and aging programs have a common set of gene expression pathways. To determine the effect of regulated genes on the diapause state and ultimately their significance in the aging process a microarray analysis was conducted using Sarcophaga crassipalpis diapausing and non-diapausing RNA probes against a partial Drosophila gene set. Results suggest approximately 353 genes are significantly up-regulated during diapause and 216 genes down-regulated. It was found that two genes present in the microarray, involved in the insulin pathway, were down regulated during diapause. Both of these genes, one a member of the phosphotidylinositol 3OH kinase (PI3K) and the other a member of the phosphodiesterase 3B complexes (Pde6), are targets for further investigation. The insulin receptor gene (InR) was not present in the microarray, but is also a candidate for investigation. RT-PCR analysis shows the genes PI3K, Pde6, and InR are significantly diapause down- regulated, thus verifying the preliminary microarray data. These genes have been isolated, cloned, and sequences have been obtained. Northern blot analysis is being conducted for further verification of gene expression. RNA interference experimentation is being conducted to characterize the role these genes have in the diapause and aging programs.


PREPARATION AND PROPERTY OF THE SOL-GEL/CARBON NANOTUBE COMPOSITE MATERIAL

Jing Wang and Mian Jiang, Department of Chemistry, East Tennessee State University, Johnson City, TN 37614.

Sol-Gel techniques are used to make glass-like silicon oxide network but possessing much lower operating temperatures than conventional glass manufacturing. These techniques depend on the hydrolysis and condensation reactions of organosilicon precursors in aqueous media, and thus provide an inclusive environment with bioaffinity. On the other hand, carbon nanotubes ( CNTs ) possess unique electric, thermal, mechanic, and chemical properties including their high surface area / volume ratio that can be further surface-functionlized to address different material or sensing demands. In this work we made a new composite material that combines the unique Sol-Gel network with conductive CNTs. Hydrolysis and subsequent condensation of tetramethyloxysilane ( TMOS ) in the presence of CNTs result in the formation of a dense, homogeneous bulky material. When coating this material onto the substrate electrode surface, the film can permeate and retain the redox-active ferricyanide. This resulting electroactive Sol-Gel/CNTs/FeCN film is very stable for repetitive voltammetric scanning as well as some harsh chemical and electrochemical environments.

The electrochemical property of this new Sol-Gel material was studied. The film has also been examined for their potentials in sensor fabrication. A unique reversible Fe(II/III) voltammetric peak emerges from the CNTs-dispersed Sol-Gel background that is tolerable for a wide pH range. The film exhibits excellent electrocatalysis for environmental nitrite and Cr(VI). These catalysis occur on the redox catalytic centers of Fe(II/III). Optimization and quantification of these catalysis were carried out and the mechanistic reaction scheme were given.

This work was supported by Starter Award from SACP ( Pittsburgh, PA ) and by RDC, Student-Faculty Grants from ETSU ( Johnson City, TN ).


POTENTIAL ENERGY SURFACE AROUND THE TROPYLIUM ION

Kenny Bullins and Thomas Huang, Department of Chemistry, East Tennessee State University, Johnson City, TN 37614

The formation and decomposition of the tropylium ion, C7H7+, in the mass spectrum of toluene is a chemical process that has been studied extensively in the past. The advances in computational power of personal computers have made the investigation of this mechanism feasible at a fairly high level of theory. The calculations that we performed were at the HF/6-31G (d, p) and the B3LYP/6-311++G (2d) levels of theory. We will show some areas of the potential energy surface around the highly symmetric tropylium ion to give a glance of possible mechanisms for its formation and decomposition. Our results have confirmed some of the mechanisms reported by literature, and in addition new areas are explored in the report.


EXTENSIONS OF THE CAYLEY-HAMILTON THEOREM

Alberto Mokak Teguia, Dept. Of Mathematics College of Arts and Sciences, East Tennessee State University, Johnson City, 37614

The Cayley-Hamilton theorem is an important result in the study of linear transformations over finite dimensional vector spaces. In this poster, we show that the Cayley-Hamilton theorem can be extended to self-adjoint trace- class operators and to closed self-adjoint operators with trace-class resolvent over a separable Hilbert space. Applications of these results include calculating operator resolvents and finding the inverse of a frame operator.