Worm Breeder's Gazette 9(1): 48

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.

Identification and Mapping of a New tRNATrp Amber Suppressor

K. Kondo, P. Powell-Abel, J. Galante, and R.H. Waterston

Figure 1

Previous experiments have demonstrated that the information 
suppressors sup-5 and sup-7 are tRNA(trp) amber suppressors (Cell 33,
575-583; P.N.A.S.  81, 6784-6788 our unpublished results).  By 
Southern analysis using a tRNA(Trp) gene as a probe there appears to 
be twelve members in the tRNA(Trp) family (P.N.A.S.  81, 6784-6788).  
We have now cloned all twelve members of this tRNA family and are 
presently sequencing each member.
Part of our studies of this gene family are aimed at trying to 
isolate suppressor alleles of each member.  From reversion studies of 
unc-13(e1091); 64) using nitroso-guanidine as a 
mutagen we have isolated a new amber suppressor mutation, st354.  This 
new mutation is a weaker suppressor than either sup-5 or sup-7.  
Altering a tRNA(Trp) to an amber suppressor creates an XbaI site in 
the anticodon loop.  By Southern analysis we have demonstrated that 
st354 has a new XbaI site in a 10kb XbaI fragment which contains a 
tRNA(Trp) family member.
Genetic mapping studies reveal that st354 is loosely linked to dpy-
13 on chromosome IV.  By 3-factor mapping we have placed it to the 
right of dpy-4.  This data is shown 
[See Figure 1]
From a 2-factor cross we have determined that st354 is about 0.6 map 
units right of ipy-4.  This tRNA(Trp) gene is at present the most 
distal marker on the right half of chromosome IV.

Figure 1