Worm Breeder's Gazette 7(1): 88

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.

Suppressible Lethals Near dpy-10 II

P. Meneely, B. Wood, P. Pesavento

We have been using a simple scheme to isolate sup-7(st5)-
suppressible lethals near dpy-10 II.  We chose this region because 
some of the interesting temperature-sensitive lethals are near dpy-10, 
but the scheme should be generally applicable to any autosomal region. 
Our immediate goal is to find and characterize amber mutants 
affecting early embryogenesis; we also hope to find null alleles of 
genes defined by ts alleles.
The method is to mutagenize dpy-10 II;unc-6 X hermaphrodites and 
mate them with sup-7 X/0 males; unc-6 is closely linked to sup-7, and 
neither dpy-10(e128) nor unc-6(e78) is suppressed by sup-7.  
Individual F1's are put on separate plates and allowed to self-
fertilize.  Broods that have Dpy's and Unc's, but no Dpy Unc's are 
candidates for mutants that carry a suppressed nonmaternal lethal 
linked to dpy-10.  To look for suppressed steriles and maternal-effect 
lethals, we pick Dpy's, Unc's, and Dpy Unc's from each brood that has 
them.  If the stock carries a linked suppressible lethal, then both 
the Dpy's and Unc's will be fertile, while the Dpy Unc's, homozygous 
for the lethal mutation and lacking sup-7, will be sterile.  The Dpy's 
are picked to maintain a homozygous mutant stock that has at least one 
copy of sup-7.  All candidates are backcrossed at least twice and 
outcrossed at least once to rol-5 II;unc-6.
So far, we have screened about 700 F1's and found 3 mutants; several 
other candidates are still being cleaned up.  One mutant is 
nonmaternal and the other two show a maternal effect; of these two, 
one is male rescuable and one is not.  All three are maintained as sup-
7 homozygotes; the mutants are suppressed poorly by one copy of the 
suppressor; no lines that segregated Dpy Unc's could be maintained.  
This scheme seems to be an effective way to isolate amber mutants in 
autosomal essential genes.  Such mutants are found at a fairly high 
frequency in the dpy-10 region.