TABLE CONTENTS

Expressed Genome of Heterorhabditis bacteriophora Reveals Interesting
Longevity and Stress Tolerance Genes in Entomopathogenic Nematodes
Grewal, P.S. (1), X. Bai (1), B.J. Adams (2), T. Ciche (3), R. Gaugler (4), P. Sternberg (5), S.
Clifton (6) & J. Spieth (6)
(1) Department of Entomology, Ohio State University, Wooster, Ohio; (2) Brigham Young University, Salt
Lake City, Utah; (3) Department of Microbiology, Michigan State University, East Lancing, Michigan; (4)
Department of Entomology, Rutgers University, New Brunswick, New Jersey; (5) California Institute of
Technology, Pasadena, California; (6) Genome Sequencing Center, Washington University School of Medicine,
St Louis, Missouri
Understanding molecular mechanisms of survival is extremely important for enhancing the
utility of entomopathogenic nematodes that are used in biological control of insects. The
entomopathogenic nematode Heterorhabditis bacteriophora is a cosmopolitan species which
is found worldwide in diverse habitats. Our recent studies have revealed correlation between
the infective juvenile longevity and environmental stress tolerance in natural populations of
H. bacteriophora. In this species, we have also shown that both the heat and cold shock
responses are correlated with trehalose metabolism. In anticipation of the availability of the
genome sequence of H. bacteriophora TTO1, we obtained and compared expressed sequence
tags (ESTs) to the ESTs and proteins of the free-living nematodes Caenorhabditis elegans
and C. briggsae using BLAST algorithms. A total of 27,380 ESTs were generated and
analyzed. We identified 334 ESTs encoding 29 aging and stress-related genes that include
components in insulin/IGF-1, JNK, and TOR signaling pathways, which shed light on the
aging mechanisms of H. bacteriophora. We found major differences in expressed genes
between H. bacteriophora and C. elegans with respect to the lipid metabolism. We also
identified 7 genes in RNA interference pathways, two of which are missing in the draft
genome of Brugia malayi. So far, we failed to identify dicer- or Argonaut-encoding ESTs.
However, as demonstrated in recently published work, RNAi pathway seems to be functional
in H. bacteriophora. We expect to identify more components as more ESTs and the
complete genome sequence become available.
5 th International Congress of Nematology, 2008 50