[Yeast] Request For PhD Position---INDIA

lijo john IGIB via yeast%40net.bio.net (by lijoigib At gmail.com)
Sat Jan 13 05:42:51 EST 2007

Hi all ,

I myself Lijo John ,completed post graduation in microbiology from ANJA
College affiliated to Madurai Kamraj University , India .
Currently Im working as a Research Assistant at the institute of Genomics
and Integrative Biology , Delhi India .

 Currently I'm  working  mainly on  these  projects.

a)  *Intracellular  thiols  mediated effects in Yeast -Mechanistic insights
and physiological regulation. *

*Here we are studying the effect of  Intracellular thiols like cysteine,
homocysteine and glutathione by using Baker's Yeast *Saccharomyces cerevisae
*. we demonstrate that cysteine and homocysteine, but not glutathione,
inhibit yeast growth in a concentration dependent manner. Using deletion
strains ( *str2_ *and *str4_*) we show that cysteine and homocysteine
independently inhibit yeast growth. Transcriptional profiling revealed that
genes coding for antioxidant enzymes like glutathione peroxidase, catalase
and superoxide dismutase. were down-regulated. These results indicate that
homocysteine- and cysteine induced growth defect is not due to the oxidative
stress. However, we found an increase in the expression of *KAR2 *(karyogamy
2)gene, a well-known marker of ER (endoplasmic reticulum) stress and also
observed *HAC1 *cleavage in homocysteine- and cysteinetreated cells, which
indicates that homocysteine- and cysteine-mediated growth defect may
probably be attributed to ER stress. Transcriptional profiling also revealed
that genes involved in one carbon metabolism, glycolysis and serine
biosynthesis were up-regulated on exogenous addition of cysteine and
homocysteine, suggesting that cells try to reduce the intracellular
concentration of thiols by up-regulating the genes involved in their
metabolism *This  work got published in   - Biochem J. 2006 May

    "Homocysteine and Cysteine mediated growth defect is not associated
with induction of oxidative stress response genes in yeast"

*b) Bakers yeast as a screening tube to reveal molecular mechanism of
toxicants. *

We are using yeast for screening various toxicants to reveal the molecular
mechanism of different toxicants which is not clearly understood . The
response of Saccharomyces cerevisiae cells to an aqueous extract of
cigarette smoke was studied in our lab. Exposure to cigarette smoke extract
inhibits yeast growth and results in global changes in gene expression
spanning many functional classes of genes. Genes involved in response to
oxidative stress are upregulated after a brief exposure to cigarette smoke
extract. Also we found   that cigarette smoke extract on yeast growth can be
reversed by treatment with anti-oxidants. Mutants lacking superoxide
dismutase gene were hypersensitive to cigarette smoke exposure. YAP1 is a
central transcriptional regulator of oxidative stress in yeast. YAP1
dependent expression of b-galactosidase was enhanced following exposure to
cigarette smoke. The overall agreement between our observations and the
recently reported effects of cigarette smoke on gene expression in rodent
and human cells suggests that yeast can be used as a model system in
toxicogenomics studies for monitoring toxic agents and studying the cellular
and molecular consequences of exposure to potentially toxic agents.

Now Im continuing these project for screening  the toxic mechanism of other
compunds  like , drugs pesticides .

*This  work got published in BBRC and the link of this article is given

*" Cigarette smoke extract induces changes in growth and gene expression
of saccharomyces cerevisae"


I would extremely appreciate, if you give me an opportunity for
proving myself.

I will be highly obliged if you kindly give information whether you have a
position available and do I stand up to your requirements. Please find My CV
and pdf format of the published articles hereby attached.

Thanking you,
Yours truly,

lijo john

Lijo John
Functional Genomics Unit
Institute of Genomics & Integrative Biology(CSIR)
Mall Road
Delhi- 110007
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