The isolation and first characterization about a balancer chromosome temporarily called Bal-X-1 was presented at the Cold Spring Harbor meeting. This chromosome when heterozygous with an X chromosome marked by
dpy-8 and
unc-3 suppress crossover on this region. Characterizing the Bal-X-1 further on, we found, that Bal-X-1 viable only in heterozygous or hemizygous form. Bal-X-1 has been marked with
lon-2(
e678) allele. Bal-X-1 (lon) males are perfectly normal and fertile. Hermaphrodites heterozygous for Bal-X-1 always segregate males about 8-20% frequencies. The males are XO. Bal-X animals homozygous for
her-1(
e1520) (kindly provided by Jonathan Hodgin) are viable but almost completely sterile. Even if they lay some eggs, their oldest progeny has never been larger than L1, which die soon. Bal-X-1 can balance the following mutants: mn-110 (BH);
let-2(
e1470) (A.F.);
let-15(
e1471) (A.F.). We are going on to learn, whether Bal-X-1 is a translocation. In these experiments, we use stocks of double homozygous for two markers ( one in the medium and one in one of the ends the autosome) of the different autosomes and measure the recombination between them. If Bal-X-1 is a translocation like Dp-1 (BH) we expect, that the recombination frequency will be changed on the autosome being involved.