Worm Breeder's Gazette 10(2): 14

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unc-51 and tRNATrp Amber Suppressors

Kazunori Kondo, Jonathan Hodgkin, Robert H. Waterston, Sydney Brenner and Ed Hedgecock

Figure 1

unc-51(e369) was found to be an amber allele by Ed Hedgecock.  
Throughout life time, unc-51 animals are severely uncoordinated, 
especially in the posterior part of the animal.  Cross suppression 
tests and reversion experiments (by EMS) were carried out.  Revertants 
isolated by Sydney Brenner (EMS) and by Ed Hedgecock (EMS) were also 
analyzed by oligomer Southern to detect the single base change at the 
anticodon of tRNA(Trp) genes.  For cross suppression tests, an unc-51; 
as constructed for each suppressor (except 
*'s), and evaluated for the extent of restoration of movement.  
Results are summarized 
[See Figure 1]
These results show that the suppression pattern of unc-51 by the 
eight known suppressors is very similar to that of unc-13: it is 
suppressed effectively by only sup-5 and sup-7, weakly by sup-24 and 
not detectably suppressed by others.  unc-13 affects the nervous 
system (I.  Maruyama, WBG vol.  9, #3, 33).  An amber allele of unc-52 
which is presumably expressed in muscle cells is suppressed to a 
similar extent by each of seven tRNA(Trp) suppressors (sup-29 was the 
only one not active).  The suppression pattern might suggest that unc-
51 is not a muscle-gene but a neuronal-gene, consistent with the 
observation that the unc-51 mutant animal has normal muscle structure.
To date about 130 revertants from unc-13, dpy-20,
n analyzed.  Eight out of 12 
tRNA(trp) genes have been converted to amber suppressors (same as WBG 
vol.10, #1, 54), but four are still silent (two are probably 

Figure 1