A new X chromosome-duplication, called mnDp57(X;I), carries the wild- type alleles of
unc-2,
unc-20, not carry the wild-type alleles of
dpy-3 or
dpy-8, which flank this region. The duplication is situated less than one map unit from
unc-54 I; it does not have much effect on crossing over on linkage group (LG) I, and it is homozygous viable. Duplication-bearing males mate well. The autosomal duplication mnDp37(III;f) is very large, extending from the left of
dpy-1 (but not including
unc-45), to the right of unc- 25 (but not including
unc-64). Because of the way in which it was made, it carries the mutation
unc-32(
e189). It occasionally recombines with the normal chromosome III. We have also obtained variants of mnDp37, some spontaneous and some apparently induced by gamma rays. One spontaneous variant is called mnDp40(III;f); it carries the wild-type alleles of
dpy-1, s several markers farther to the right, such as
lon-1,
unc-36 and
unc-50. Hermaphrodites carrying mnDp40 give more nullo-duplication self- progeny than do hermaphrodites carrying mnDp37.The X-ray-induced translocation mnT4(III;IV) was identified by virtue of its property of reducing the apparent recombination between
dpy-1 and
unc-32 to less than 1%. Recombination on LGIV is not greatly affected. There is strong pseudolinkage between
dpy-1 III and
unc-8 IV (about 1% recombination), suggesting that the latter is in the neighborhood of a breakpoint. We have evidence for significant nondisjunction between mnT4 and the normal chromosome III, leading to animals that are mnT4/III/III.