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THE THOMAS LABORATORY
Our laboratory is located in Science Building 166, Department
of Natural Sciences
We Build Undergraduate Research Biologists Daily!
Goals for my laboratory
Understand the molecular basis of gene expression during environmental stress
and exposure to plant growth regulators.
Engineering crops against insect, viral and environmental insult.
Promote collaborations and provide employment/higher education directions
for students.
Current Topics of Reseach in My Laboratory
Gene expression that accompanies salt stress must result from the reception
of a signal and a chain of events that affects gene expression and physiology.
Besides NaCl , and the plant growth regulators ABA and cytokinins, a recent
extension of my stress studies involve metal stress. Using copper as a model
heavy metal we have shown that copper stress can be exerted during germination
and/or vegetative growth. Some, but not all NaCl linked stress indicators
are also induced by heavy metal stress. For this reason, we are using differential
display of cDNAs to delineate differences in RNA populations in the presence
or absence of stress in tolerant Mesembryanthemum crystallinum and
non tolerant species Arabidopsis thaliana. We are also engineering
plants as bioremediators and potentially bioindicators of copper. Normally,
yeast accumulate CUP-1 encoded protein in copper excess. We have over-expressed
the CUP-1 protein in transgenic Arabidopsis thaliana and tobacco
in an attempt to equip the plants with a greater copper binding ability,
conferring some degree of metal tolerance. Studies are underway to determine
the effects of CUP-1 on plant metal tolerance.
Additional studies are now focused on the isolation genes induced by copper
metal using several methods including PCR and differential display. One
metalothionein has been isolated from Mesembryanthemum crystallinum which
confers copper tolerance.
Nearly 40% of the national insecticide consumption involves the cotton crop.
Insecticide production within cotton may be more effective and impact less
upon the land and the people processing the crop. We have cloned, expressed
and patented three insecticidal protease inhibitors from Manduca sexta
L. (the tobacco horn worm). Results indicate that protection against insect
reproduction occurs on plants expressing PIs (Plant Cell Reports 14: 758-762,
Plant Physiol. and Biochem. 33(5): 611-614). An industrial proposal has
been submitted to use these PIs together with a chitinase and a "Super
promoter" to improve insecticidal activity in Gossypium hirsutum
L. cotton. Furthermore, a third gene, tryptophan decarboxylase, has been
engineered and expressed in transgenic tobacco and petunia (Plant Physiology
109: 717-720). These plants convert tryptophan to tryptamine, an indole
alkaloid. Below is a western blot of control (35S-GUS) and TDC expressing
tobacco from the above-mentioned article. Insect tests on diets containing
tryptamine or transgenic plants producing tryptamine strongly suggest an
opposite correlation between the presence of tryptamine and the extent of
insect feeding damage.
A study of plant single stranded DNA viruses is directed towards novel anti-viral
strategies. We have begun producing transgenic tomatoes expressing anti-sense
RNA constructs to movement proteins of Chino del Tomate, a geminivirus.
In addition efforts to clone and sequence the A component of this virus
are underway.
We are happy to have a visiting scientist, Ms. Elizabeth Godsall. Liz
completed her BSc from University of Nottingham and is most recently from
Nickerson BIOCHEM Ltd, in Cambridge England. Her project is focused on understanding
stress and copper inducible gene expression in metallophytes and glycophytes.
Other Interesting Links:
E-mail JCTHOMAS@umd.umich.edu