2008 Proceedings - St. Cloud State University

Abstracts
Session C Biochemistry North Glacier
Toxoplasma Gondii CDK7 Ortholog Protein-Protein Interactions
Toxoplasma gondii is an obligate intracellular protozoan parasite with the ability to infect humans. Congenital toxoplasmosis may lead to
fetal abortions. Immunocompromised individuals, such as those with HIV, have increased mortality, when infected with T. gondii. Once
within a host, the tachyzoite form of the parasite divides asexually by endodyogeny, resulting in the formation of two daughter cells within a
mother cell. This unique cell cycle could be exploited to develop a better pharmacological treatment for this disease. Unfortunately, this
method of cell division is not well understood. However, homologous cell division protein coding genes exist within the T. gondii genome.
One of these proteins, cell division kinase 7 (CDK7) activates other CDKs by phosphorylating a threonine residue on their T-loop domains.
This activity is dependent upon interaction with a cyclin H (CycH) subunit. The CDK7/CycH interaction is strengthened by the interaction of
a third subunit, Mat1. This trimeric complex is termed the CDK activating kinase (CAK). To determine if these or other interactions occur
with the T. gondii CDK7 homolog a screen was performed against a cDNA library with the yeast 2-hybrid system. The gene sequences of
the interacting proteins were obtained and then identified using the T. gondii genome database, www.toxodb.org. Identification of the
protein-protein interactions of these cell cycle regulators would increase our understanding of the process of endodyogeny and could lead
to better parasite-targeted pharmacological treatment.
Presentation Index: C2
Time: 9:50 a.m.
Department: Biological Sciences
Project Sponsor(s):
Student Presenter(s): Reberg, Alexander
Kvaal, Christopher
Taratogenic Effects of Ethylene Glycol Ethers on Xenopus Laevis Development and Role of Aldehyde Dehydrogenases in
Determining Taratogenicity
Aldehyde dehydrogenase enzymes (ALDHs) are known to toxify ethylene glycol ether aldehydes in animal models. ALDHs are expressed
differentially during the development of Xenopus. Accordingly, the purpose of this research project is to identify ALDHs that may play a
role in toxification of ethylene glycol ether aldehydes during the developing Xenopus laevis embryos. The toxicity of ethylene glycol ether
aldehydes was made by inducing mating in Xenopus laevis and growing the embryos at varying concentrations of ethylene glycol ether
aldehyde concentrations, the two ethylene glycol ethers used in this study were ethoxyethanal and butoxyethanal. To determine which
ALDH was present, various stages of X. laevis development were collected and subjected to an ALDH assay to determine if ALDH was
present. The stages that showed the most ALDH activity were further subjected to isoelectric focusing. Butoxyethanal was found to be
toxic to developing embryos at a concentration of 500 ìM or greater, whereas ethoxyethanal was not toxic at levels of 1 mM. The assays
showed that ALDH activity was present in the embryos at various stages and aldehyde dehydrogenase activity seems to correlate with eh
toxicity. Identification of ALDHs present in various stages of Xenopus development is on-going.
Presentation Index: C3
Time: 10:10 a.m.
Department: Chemistry; Biological Sciences
Student Presenter(s): Petersen, David
Project Sponsor(s):
Sreerama, Lakshmaiah; Gregory, Dan;
Schuh, Timothy
Toxoplasma Gondii CYC2 Ortholog Protein-Protein Interactions
Toxoplasma gondii, an obligate intracellular pathogen that infects the nucleated cells of warm-blooded vertebrates, is the causative agent
of human toxoplasmosis. T. gondii infection rates in human populations worldwide range from 10-90%. Twenty-two percent of Americans
are seropositive. As a member of the phylum Apicomplexa, it is related to several parasites, including Plasmodium Falciperum, the
causative agent of malaria and Cryptosporidium Pavum, which causes life threatening prolonged diarrhea to immunocompressed patients.
T.gondii has a very a complex lifecycle composed of sexual cycle, which occurs in cats, the definitive host, and asexual cycle, which is
composed of two distinct , tachyzoite and bradyzoite, stages, which occurs in warm blooded mammals including humans. Just like all other
eukaryotes, T.gondii cell cycle is regulated by sequential activation of different CDK/Cyclin complexes. Better understanding of these
interactions will lead to designing a control of T.gondii cell cycle and possibly of other related Apicomplexan parasites. Cyclins are positive
regulatory subunits of cdks whose levels oscillate during cell cycle progression. Cyclin 2 was chosen as a bait, and a yeast two-hybrid
screen was performed against a cDNA library. The interactive proteins were sequenced and identified using bioinformatics tools. Further,
an effort was made to produce and purify cyclin2 protein with an objective of studying the interactions in detail.
Presentation Index: C4
Time: 10:30 a.m.
Department: Biological Sciences
Project Sponsor(s):
Student Presenter(s): Kane, Rahul
Kvaal, Christopher
St. Cloud State University Student Research Colloquium 37
April 22, 2008