Worm Breeder's Gazette 11(1): 26

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.

Trans-splicing of tra-2: Variations on a Theme

Patricia Kuwabara and Judith Kimble

We have previously reported the isolation and characterization of a 
cDNA clone corresponding to the 4.6 Kb transcript of tra-2 (1).  
Primer extension and S1 protection analyses of the 5' end strongly 
suggested that this tra-2 transcript was trans-spliced.  Sequence 
ambiguities impeded identification of the leader by dideoxy sequencing 
RNA using reverse transcriptase.  Consequently, we have used a PCR 
method (2) to obtain additional cDNA clones that encompass the entire 
5' end of the 4.6Kb transcript.  In brief, the 4.6Kb transcript of tra-
2 is trans-spliced to the SL-2 sequence originally found associated 
with the C.  elegans gene, GAPDH (3).  Surprisingly, we have also 
isolated 5 other cDNA clones that contain variations in the SL-2 
sequence.  These differences include insertions and deletions that 
result in a 23 or 21 nucleotide leader, and base substitutions in the 
original SL-2 sequence.  We do not know if these differences are 
artifacts induced during the PCR reaction or if they reflect 
heterogeneity among SL-2 genes.  If the latter, then this observed 
heterogeneity could explain our inability to identify the tra-2 leader 
by reverse transcriptase sequencing.  These results also imply that a 
transcript can be trans-spliced to leader sequences encoded by 
different genes, perhaps with different regulatory functions.