Worm Breeder's Gazette 11(4): 25

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.

Cloning and Sequencing the C. elegans Na+/H+ Antiporter Gene

Marco A. Marra, Shiv Prasad, Denise V. Clark and David L. Baillie

The cosmid C11F2 has been shown to rescue two alleles of let-56, s46 
and s173, using the technique of germ line transformation (1).  Two 
adjacent PstI subclones of this cosmid detect transcripts on Northern 
blots.  Neither of these two PstI subclones have been shown to rescue 
let-56.  One PstI subclone (fragment 'q', see 2) detects a 2.4 kb 
message.  This PstI subclone was used to screen a lambda gt10 cDNA 
library obtained from B.  Meyer.  This resulted in the isolation of a 
1.3 kb cDNA, found to be contained entirely within fragment q.  This 1.
3 kb cDNA (called 'C2'; 2) was sequenced and found to contain a single 
long open reading frame of approximately 1200 nucleotides.  This cDNA 
was incomplete, representing the 3' portion of the expected message (3)
.  When the inferred amino acid sequence of this single long open 
reading frame was used to search the translated EMBL DNA databank (
release 20), significant homology was detected with the human growth 
factor activatable Na+/H+ antiporter protein sequence (3;4).
We have commenced sequencing genomic C.  elegans Na+/H+ antiporter 
DNA contained within a 6.2 kb HindIII fragment (called 'FH6'; 2) 
subcloned from fragment q.  This subclone contains all of the C2 cDNA 
homologous region, plus an additional 800 nucleotides 5' of the C2 
homologous sequence.  Preliminary results indicate that the 5' end of 
the C.  elegans Na+/H+ antiporter is not entirely contained within the 
additional 800 nucleotides of genomic DNA immediately upstream of the 
C2 homologous sequence residing within FH6.
Currently, we are attempting to subclone the 5' end of the C.  
elegans Na+/H+ antiporter gene from fragment q.  In addition, we will 
screen a lambda zap cDNA library obtained from B.  Barstead in order 
to recover a full length Na+/H+ antiporter cDNA.  Questions we intend 
to address include: (1) whether let-56 encodes the C.  elegans Na+/H+ 
antiporter gene and (2) whether the C.  elegans Na+/H+ antiporter 
protein is regulated in a manner similar to its human equivalent.