Worm Breeder's Gazette 9(3): 43

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Duplications of the ama-1 IV Gene

T.M. Rogalski, A.M.E. Bullerjahn and D.L. Riddle

Figure 1

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 
{Figure 1}

Figure 1