Program of the 2001 International Worm Meeting - Sternberg Lab ...

1069
immune system of the human host. This attack
includes the release of a variety of reactive
oxygen species from stimulated host phagocytic
cells which cause an external oxidative stress.
This means that O. volvulus must have evolved
additional mechanisms to protect itself against
the immune response of the human host to
ensure its own survival.
A glutathione S-transferase of O. volvulus
(Ov-GST-3), shown to be upregulated in
response to oxidative stress, is suspected to be
involved in the defense against the host’s
immune system. To have the chance to
investigate the function of this molecule in more
detail, transgenic C. elegans (AK1) containing
the Ov-GST-3 gene under the control of a C.
elegans promotor (let-858) were generated. The
comparison of AK1 worms and control worms
on plates with artificially produced oxidative
stress revealed significant higher survival rates
of the transgenic line. The extent of lipid
peroxidation, one type of damage caused by
oxidative stress, is also reduced in the transgenic
worms as determined by the measurement of the
level of malondialdehyde (MDA). These
findings clearly demonstrate that the
overexpression of Ov-GST-3 confers an
increased resistance to oxidative stress in the
transgenic AK1 worms.
1070. ENHANCEMENT OF
STEINERNEMA CARPOCAPSAE
DESICCATION TOLERANCE BY
GENETIC IMPROVEMENT
Christopher W. Brey, Randy
Gaugler
1070
Department of Entomology, Rutgers University,
New Brunswick, NJ 08901
The entomopathogenic nematode (ENP)
Steinernema carpocapsae , is an important
biological control agent for a wide range of soil
dwelling insect pests. However, the field
efficacy of this ENP is limited by its sensitivity
to high drought and salinity conditions. We
report efforts to improve the desiccation
tolerance of S. carpocapsae by transforming it
with the trehalose-6-phosaphate synthase (tps1)
and glycogen synthase(gsy1)genes.
Trehalose-6-phosphate synthase and glycogen
synthase are enzymes involved in the
biosynthesis of trehalose, a disaccharide that
accumulates to stabilize the lipid biomembranes
in many organisms when in response to stress.
To increase desiccation tolerance by genetic
modification, we have cloned gene tps1 from
yeast and C. elegans into expression vectors
pJJ436 and pPD95.67, respectively. In addition,
we also cloned gsy1 from Steinernema feltiae
into expression vector pJJ436. Vector pJJ436
contained the Ce sq-1 promoter, whereas
pPD95.67 contained the promoter of the tps1 Ce
gene. All vectors contained the gfp
transformation gene which was used as a
selection marker. Vector constructions (yeast:
pJYeTr.1; C. elegans : pP67CeTr.2; S. feltiae :
pJSfTr.1) were microinjected independently into
young S. carpocapsae females (48 h from
infective juvenile stage). Injected females were
mated with noninjected males for 2-4 days and
progeny were screened for gfp expression. After
selecting and retaining gfp expressing
individuals for three generations, F3 progeny
were tested for desiccation tolerance. We will
present details of our methodology and results
in our presentation.