Worm Breeder's Gazette 9(3): 43
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.
We have recently isolated a duplication of the left arm of LG IV (
mDp1) which we intend to use to refine the existing fine-structure map
of ama-I (see Bullerjahn and Riddle: this issue). mDp1 was obtained in
a screen designed to identify duplications and deficiencies of the dpy-
13 region. Briefly, N2 males that had been exposed to 1500 rads 7-
radiation were mated to unc-17(e113)dpy-13(e184) hermaphrodites and
the Fl generation was screened for the presence of rare wild-type
length (e184/+/+) or Dpy (e184/mDf) individuals among the semi-Dpy (
e184/+) cross progeny. Six Wild and two Dpy worms were found after
screening approximately 1500 Fl hermaphrodites. One of the Dpy mutants
carried an apparent dpy-13 allele whereas the other carried a small
deficiency (mDf 10), which includes let-278,
the strains established from wild-type cross progeny have been
characterized, and both appear to carry duplications (mDp1 and mDp2).
mDp1 carries wild-type alleles of dpy-9, dpy-13,
ng that the entire left arm of LG
IV is duplicated. The unc-8, e
not included in mDp1, thereby placing the duplication breakpoint in
the interval between unc-S and unc-8. This duplication recombines with
the normal fourth chromosome at a low frequency since we have found
both Dpy and semi-Dpy Unc recombinants in an unc-17(e113)dpy-13(e184)
IV; mDp1(lV:III) strain. In addition, mDp1 appears to be homozygous
viable, albeit slow-growing.
We have determined that mDp1 is linked to unc-32 and to unc-45 but
not unc-25, suggesting that this duplication is attached to the left
arm of LG III. In these mapping crosses suppression of dpy-13(e184) is
the phenotypic marker for the duplication (e184/+; mDp1 are wild;
e184/e184; mDp1 are semi-Dpy).
In contrast to mDp1, the mDp2 duplication appears to carry only a
small region of LG IV. Of the 5 genes tested, only dpy-13 and ama-1
are included in mDp2 whereas unc-17,
We have not tested this duplication for linkage to any chromosome
besides the X: however, mDp2 is most likely a free duplication since
it is apparently lost at a high frequency.
Below is a genetic map of LG IV showing the extent of both
duplications.
{Figure 1}