Subject: Dp(1;Y)s for the 10C to 11D Region
Isolation and Characterization of Duplications of the 10C to 11D Region of
the Drosophila X chromosome
Millicent A. Gornek, Kevin P. Bogart and Kevin R. Cook
Bloomington Drosophila Stock Center
Indiana University
Here we describe a screen for Y-linked duplications of the X chromosomal
region distal to 11D3-8.
In(1)sc260-14 with breakpoints 1B2-3;11D3-8 was recombined onto C(1;Y)6
to create C(1;Y)6, In(1)sc260-14. An attached-X stock of C(1;Y)6,
In(1)sc260-14 was generated that lacked a free Y chromosome. Males from
this stock were irradiated at 4000 rads using a cesium source and mated to
homozygous y1 w1 females. 93,000 progeny (54,000 males) were screened
for the presence of y+ w- males. Stocks were established by crossing
these males to y1 w1 females. Ten out of thirty-nine y+ w- males
were fertile and were used to make stocks.
The screen was designed to recover deletions within C(1;Y)6,
In(1)sc260-14 which extend from some point distal to the 11D3-8
breakpoint to X centric heterochromatin yielding a Dp(1;Y) chromosome with
the following structure: the X tip to 1B1,2; a segment from 11D3-8 to a
random breakpoint in region 10 or 11; a portion of X heterochromatin; a Y
chromosome. The XLt to 1B1,2 segment carries a wild type allele of y, which
allows the Dp(1;Y) chromosomes to be followed in crosses.
Since the breakpoint of interest in these Dp(1;Y) chromosomes is juxtaposed
to centric heterochromatin, determining precise breakpoints is impossible
cytologically. Nevertheless, the bands visible in polytene preparations
gave minimal extents of the duplicated regions:
Dp(1;Y)BSC1 10C1,2;11D3-8
Dp(1;Y)BSC2 10E1,2;11D3-8
Dp(1;Y)BSC3 11B1,2;11D3-8
Dp(1;Y)BSC4 11B1,2;11D3-8
Dp(1;Y)BSC5 11B18;11D3-8
Dp(1;Y)BSC6 11B18;11D3-8
Dp(1;Y)BSC7 11B18;11D3-8
Dp(1;Y)BSC8 11C3-4;11D3-8
The polytene bands closest to the chromocenter in squashes appear to be
from region 10 or 11.
More precise placement of breakpoints for some, but not all Dp(1;Y)
chromosomes came from comparing our cytology to information about the
rescue of recessive mutations in regions 10 and 11 by the Dp(1;Y) chromosomes.
Dp(1;Y)BSC1 rescued
P{lacW}l(1)G0241G0241 10D1-3
P{lacW}l(1)G0102G0102 10E1-4
In(1)m38c, m38c 10E1-2;13B4-5
dy1 10E3-4
P{lacW}l(1)G0111G0111 10E
qs1 10F1-7
fw34e 11A4
tsg2 11A2
P{lacW}l(1)G0060G0060 11B14-C2
We found no mutations distal to l(1)G0241 rescuable by Dp(1;Y)BSC1. The
chromosomes with lethal mutations in 10BC we tested likely carried
additional lethals. In this case, complementation tests did not allow us to
refine the cytology. We suggest 10C1,2;11D3-8 as the provisional cytology
of Dp(1;Y)BSC1 until a more precise distal breakpoint can be determined.
Dp(1;Y)BSC2 rescued
P{lacW}l(1)G0102G0102 10E1-4
In(1)m38c, m38c 10E1-2;13B4-5
dy1 10E3-4
P{lacW}l(1)G0111G0111 10E
qs1 10F1-7
fw34e 11A4
tsg2 11A2
P{lacW}l(1)G0060G0060 11B14-C2
but did not rescue
P{lacW}l(1)G0241G0241 10D1-3
These complementation tests are consistent with our cytological analysis
which showed a breakpoint distal to 10E1,2, but do not provide any
additional information for refining the position of the distal breakpoint.
We suggest using 10E1,2;11D3-8 as provisional breakpoints for Dp(1;Y)BSC2.
Dp(1;Y)BSC3, Dp(1;Y)BSC4, Dp(1;Y)BSC5, Dp(1;Y)BSC6, Dp(1;Y)BSC7 and
Dp(1;Y)BSC8 all rescued P{lacW}l(1)G0060G0060 (11B14-C2), but not tsg
(11A2) or more distal mutations. This is consistent with the cytology of
Dp(1;Y)BSC3 and Dp(1;Y)BSC4, but does not refine their distal 11B1,2
breakpoints; we suggest provisional breakpoints of 11B1,2;11D3-8. These
complementation results allowed a more accurate placement of the distal
breakpoints of Dp(1;Y)BSC5, Dp(1;Y)BSC6, Dp(1;Y)BSC7 and Dp(1;Y)BSC8; we
suggest provisional breakpoints 11B14-C2;11D3-8.
Two Dp(1;Y) chromosomes, Dp(1;Y)BSC9 and Dp(1;Y)BSC10, were recovered
which appear to carry only X tip material; they retained the 1B1,2
band, but no bands from region 11 were apparent. They did not rescue
P{lacW}l(1)G0060G0060 (11B14-C2), the mutation closest to the 11D3-8
breakpoint in In(1)sc260-14.