--Etienne Kaszas and Peter A. Peterson
This is an extension and amplification of the Nowick and Peterson study
(1981). In this study, 190 germinal derivatives from the autonomous allele
a-m(papu)--see
cross below--were isolated to study the transposition of En from
its initial site at the A1 locus. The transposition of En
at the new location was confirmed by crosses of the stable colorless or
pale derivatives to responsive tester lines (a-m(r) and a-m1).
Our study, although based only on 190 derivatives, is in agreement with
Nowick and Peterson's data (MGG 183:440-448, 1981): 24% of the derivatives
do contain a linked En, as it appears in the table of percentages
below. Around 10% of the lines do contain an independent
En. The
other classes indicate either an En loss, or a changed
En
that gave incomplete signals, or two or more Ens.
| Study* | no En | En indep. | En linked | Two or more Ens | Low freq. of En |
| 1 | 28 | 12 | 29 | 21 | 10 |
| 2 | 16 | 9 | 24 | 25 | 26 |
2, This study, 1988 and 1989: 190 derivatives analyzed
Cross: a-m(papu)/a sh2 x a sh2; progeny expected are 1/2 spotted round and 1/2 colorless shrunken; exceptions are colorless round or pale round.
An estimate of A1 - En distance was calculated (direction undetermined), as shown in the figure. This distribution is not random. 60% of the values are in the range of 5 to 20 map units. These results are supportive of Nowick and Peterson (1981), where En transposed preferentially between 5 and 15 map units from A1. Tests for precise location of En are underway.
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