Worm Breeder's Gazette 10(3): 79

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.

A New Trans-Spliced Leader in C. elegans

Xin-Yun Huang and David I. Hirsh

While determining the 5' ends of C.  elegans GAPDH mRNAs by primer 
extension sequencing, we found a new trans-spliced leader (SL2).  The 
previously identified SL is present on mRNAs from three of the four C. 
elegans GAPDH genes.  However, a new 22-nucleotide spliced leader 
sequence is found on mRNA from one of the four GAPDH genes.  
RNA Northern analysis showed that the SL2 is present on many RNAs 
isolated from C.  elegans var.  Bristol, C.  elegans var.  Bergerac 
and C.  briggsae, but not on RNAs from Panagrellus redivivus and 
Haemonchus contortus.  In this regard it differs from the original SL 
that is found in other nematodes.  The hybridized RNAs showed a broad 
spectrum of different molecular weights.
From the genomic Southern blot, it seems there are two clusters of 
SL2 genes.  We have screened a C.  elegans EMBL4 genomic library.  Two 
groups of phages were isolated.  Using the phage DNAs as templates, 
two kinds of SL2 genes have been sequenced.  These two genes are 
nearly identical in the SL RNA region but differ in the 5' and 3' 
flanking regions.  A consensus Sm binding site of snRNAs is present.  
The SL2 RNA can be folded into a secondary structure similar to that 
proposed for the original SL RNA.  The SL2 RNA probably has a TMG cap 
because it can be precipitated by anti-TMG-antibody.  The original SL 
and the new SL2 are similar; 16 out of 22 nucleotides are the same in 
the best alignment.