*Dissertation Defense Announcement:
To:  The George Mason University Community*

*Neeraja Podugu
PhD Biosciences Candidate
*Date:   Monday November 1, 2010
Time:   11:00 a.m. 
Place:  George Mason University
** 	     Room 249, Bull Run Hall
	     Prince William campus <>
Dissertation Chair: Dr. James D. Willett
Committee members: Dr. Yuntao Wu, Dr. Jenefir Isbister, Dr. Jennifer Weller *
*Title: "Stress Related Changes in Purine, Tyrosine and Trytophan Metabolites of /Caenor/*/*habditis Elegans**"*/

A copy of the dissertation is on reserve in the Johnson Center Library, 
Fairfax campus.  The doctoral project will not be read at the meeting, 
but should be read in advance.

All members of the George Mason University community are invited to attend.


/Caenorhabditis elegans /has been used as a model organism in many areas 
of research over the last few decades. This research investigated stress 
related changes in /C.elegans/ following exposure to different 
components of /B.anthracis /and varying dosages of lead acetate. 
Metabolites of purine, tyrosine and tryptophan pathways of /C.elegans/ 
were measured using/ /high profile liquid chromatography coupled with 
electrochemical detection. Perturbations in metabolites of these 
pathways in /C.elegans /were measured and compared to the metabolites of 
the untreated. /C.elegans / cultures grown under axenic and monoxenic 
conditions responded differently to the same stressors. The results from 
this research support the hypothesis that a relationship exists between 
the initial stress response and the subsequent changes in the metabolic 
constituents of purine, tyrosine and/or tryptophan pathways of /C.elegans/.

 The exposure of axenic mixed cultures of /C.elegans /to a /Bacillus 
anthracis/ three- toxin combination resulted in an acute response 
showing perturbations in purine, tyrosine and tryptophan pathways. 
Increasing the concentration of lead affected growth in axenic young, 
reproductive processes in axenic middle aged after 1.5 days of exposure 
whereas the adult /C.elegans/ lysed. Perturbations in analytes of 
purine, tyrosine and tryptophan, as well as unknown analytes specific to 
the life stage and dosage of lead treatment, were observed. Axenic and 
monoxenic /C.elegans/ demonstrated time and dose-dependent responses to 
lead exposure. Axenic /C.elegans/ cultures responded to biological 
stressors and lead acetate more rapidly than monoxenic cultures, 
suggesting that axenic cultures could provide a superior model system 
for measuring acute stress responses.