Worm Breeder's Gazette 9(3): 58

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.

Further Analysis of C. elegans Introns

C. Fields, D. Hirsh and T. Blumenthal

Figure 1

We have continued the analysis of C. 
described in the Nov. '85 Gazette. Several 
introns from collagen and other genes have been added to the worm 
intron data set, enlarging it to 72 examples.
The consensus sequence 5'-GTAAGTT ... TTTCAG-3' for C. 
plice junctions derived from the original 
data set of 53 introns also accurately describes the splice junctions 
in the larger data set. m e underlined nucleotides are absolutely 
conserved. An A has been found in the -3 position in the 3' junction 
in two cases; G has not been observed in this position.
We have re-examined the question of whether a lariatforming 
consensus sequence exists in C. ted 
previously, many worm introns lack the eukaryotic consensus lariat-
forming sequence YNYTRAY (R=purine, Y=pyrimidine). We have performed a 
new search of the larger data set for any weaker consensus sequence. 
78% of the 72 introns were found to contain the sequence YRAY; the 
remaining 22% contain either YRAR or RRAY. The consensus sequence 
derived from this search 
{Figure 1}
where the underlined RA is absolutely conserved, and the remaining 
nucleotides occur at the indicated frequencies. 89% of these sequences 
occur between positions -15 and -35, with respect to the conserved G 
of the 3' splice junction.
In the absence of experimental data, it is unclear whether this 
consensus sequence plays any role in worm splicing. We are performing 
an information-theoretic analysis of the regions of the introns 
surrounding these sequences in order to assess the statistical 
significance of the consensus.

Figure 1