Worm Breeder's Gazette 13(5): 67 (February 1, 1995)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

emb-5 homolog in Caenorhabditis briggsae

Ken-ichiro Higashi and Johji Miwa

Fundamental Research Laboratories, NEC Corporation
34 Miyukigaoka, Tsukuba, Ibaraki 305 JAPAN

The emb-5 gene is required for the correct timing of division ofgut
precursor cells during gastrulation in C. elegans.  A protein database
search indicates that the predicted emb-5 gene product has no significant
similarity to any other known proteinsexcept for the Saccharomyces
cerevisiae nuclear protein SPT6, which has been shown to affect the
transcription of various genes. To investigate the universality and
general importance implicated bythe emb-5 gene product in biological
systems, we have begun to search for emb-5 homologs in other animals.

First, we looked for an emb-5 homolog in C. briggsae, a close kin to C.
elegans.  Genomic DNA from C. briggsae was digested with several
restriction enzymes and hybridized in Southern blots with a C-terminal
fragment(about 1.7 kb) of emb-5 cDNA as a probe.  We detected a 2.5-kb
positive fragment in ClaI digested DNA and cloned it into pBluescript KS(-
).  Sequencing of this fragment has revealed that it is a C-terminus of an
emb-5 homolog.  Next, we constructed a C. briggsae genomic DNA library of
Sau3AI partially digested DNA cloned in lambda DASH II vector, and
obtained the clones that hybridyzed to the above 2.5-kb ClaI fragment. 
Finally, we sequenced the entire emb-5 homolog DNA by analyzing these

The predicted amino acid sequence (1521 aa) has 80% homology to that of
EMB-5, although homology is 60% at the DNA level, and there exist both
highly conserved and less conserved regions.  The mutation site of hc61 is
located in a highly conserved region.  The positions of introns found in
the emb-5 homolog are almost the same as in C. elegans emb-5, although the
intron corresponding to the 6th one of C. elegans is missing in C.
briggsae.  There is little obvious identity in the lengths and sequences
of corresponding introns between C. briggsae and C. elegans.

We are trying to rescue the hc61 mutation of C. elegans by injecting C.
briggsae DNA.