Worm Breeder's Gazette 6(1): 21

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 Characterization of "BAL-X-1" (szT1)

P. Deak, A. Fodor

Figure 1

In the last issue we reported about a chromosome rearrangement (then 
called Bal-X-I; the new name is szT1), which : 
1.  suppresses crossover in the dpy-8 f the 
X chromosome; 
2.  is marked with lon-2 (e678); 
3.  is homozygous lethal; 
4.  as hemizygous (her-1) hermaphrodite is sterile; 
5.  as hemizygous male is viable and fertile; 
6.  segregates about 8-20% of males.  
We are interested to know whether szT1 is an inversion, 
translocation or free duplication.  If it were a homozygous lethal 
inversion, 25% egg lethality could be expected.  If it were a free 
duplication, the population would tend to lose the balancer chromosome.
However, if it were a translocation, a high rate of embryo mortality 
could be expected.  In an experiment eggs were collected from young 
immediately and viable adult progeny were scored two days later.  From 
1233 fertilized eggs counted, 385 viable adult progeny developed (31%).
This finding suggests that szT1 might be a translocation.  In 
pseudolinkage experiments we wanted to establish which autosome is 
involved in this translocation.  Double mutants homozygous for unc-3 (
e151) and different dpy alleles from different linkage groups were 
combined and crossed out with szT1 (lon-2) males.  The frequencies of 
recombination between lon-2 and the autosomal dpy alleles were studied.
(Only the males were scored, because all male categories were viable.
[See Figure 1]
This corresponds to p = 0.5 between unc-3 and the autosomal markers, 
and p = 0.5 between lon-2 and markers of LG II, III, IV and V, but p 
between lon-2 and dpy-5 (I.) was 0.
We concluded that the szT1 chromosome is an (X;I) translocation.

Figure 1