no longer in operation, the Expression Project has proved a rich
source of genetic information.
objective of the project was to define the RNA expression profiles
in specific tissues and cells, and developmental stages of C.
elegans. Two complementary approaches were applied: serial
analysis of gene expression (SAGE), and the construction of promoter::GFP
fusions for in vivo analysis of gene expression.
objective was the development of a protein expression baseline
for specific tissues during development.
Monitoring in vivo expression of the fusion constucts in transgenic
worms allows the determination of the developmental stage, tissue,
and in some cases, the cells where a particular gene is expressed.
Our goal was to build promoter::GFP fusion constructs for C.
elegans genes that have human orthologues. We analyzed approximately
2000 of the 5000 genes that fall into this category. When coupled
with SAGE and knockout data, this provides valuable and more complete
expression profiles for cells, tissues, and developmental stages.
SAGE is a sensitive and specific method for obtaining qualitative
and quantitative information on expressed RNAs. SAGE also allowed
us to identify non-protein-coding genes, and provided insight
into alternatively spliced mRNA isoforms and their relative abundance
examined total mRNA populations in all developmental stages, both
in whole worms and in specific cells and tissues. We have generated
17 SAGE libraries, which include all developmental stages, mutation-specific
populations, and specific tissues and cells, totalling approximately
1.8 million observed tags. Tissue- and cell-specific libraries
were generated from FACS-sorted cells marked by expression of
specific promoter::GFP fusions. To date, we have SAGE libraries
for purified embryonic muscle, gut, and a subset of neurons.