1022-7954/01/3711- $25.00 © 2001
Russian Journal of Genetics, Vol. 37, No. 11, 2001, pp. 1272–1274. Translated from Genetika, Vol. 37, No. 11, 2001, pp. 1513–1516.
Original Russian Text Copyright © 2001 by Subocheva, L. Romanova, N. Romanova, Kim.
Transposition of mobile genetic element
(MGE4) results in genetic instability and affects many
morphological traits [1, 2]. The number of
is substantially increased in a mutator strain (MS) and
its derivatives; the element is transposed throughout the
genome and causes mutations in various genes. The
resulting mutations are subject to natural selection,
which occurs in laboratory conditions, and can be iso-
lated in individual strains. Some of these mutations
may lead to behavioral alterations. We think it interest-
ing to study the behavioral characters of unstable
strains, since this makes it possible to identify genes
involved in their formation. With methods commonly
employed in behavioral genetics of
we analyzed the olfaction and the locomotor activity in
ﬂies of several strains that differed in the allelic state of
gene and had or had no transpositionally
active copies of
MATERIALS AND METHODS
Flies were bred on a raisin–yeast medium at 25
and kept at room temperature (19–20
C) after eclosion.
The following strains were used.
Strain 1 was a stable strain (SS). The X chromosome
was marked by the
) mutation and carried the
mutation of the
gene . The strain
copies capable of transposition.
Strain 2 was a substrain originating from strain
MSn1. MSn1 was obtained by introducing an active
, which was cloned from MS, into SS  and,
consequently, carried many transpositionally active
copies. The X chromosome was marked by
) mutations  and carried
mutation. The substrain was stabilized
with the FM7 balancer X chromosome (In(1)FM7,
dm sn B
); the cytological location of the inver-
sions was 1A–1B2/20F–20E/15E–20A/15D–11F4/4E1–
11F2/4D7–1B3/20F. The FM7 chromosome carried an
marker mutation. All other chromosomes
were identical in strains 1 and 2. Thus, strain 2 ﬂies that
lacked the FM7 chromosome were isogenic with strain
1 ﬂies, but contained transpositionally active
copies in the genome.
Strain 3 was another substrain isolated in parallel
with strain 2.
Strain 4 was the wild-type Canton S strain.
Virgin females and males were taken from each
strain and tested for behavioral traits three to ﬁve days
Olfactory sensitivity assays.
Parameters of olfactory
sensitivity were studied with the use of a two-ray olfac-
tometer designed according to Benzer  with a modi-
ﬁcation in odorous substance supply . As olfactory
stimuli, we used acetic acid (an attractant), benzalde-
hyde, and ethylacetate (repellents). In the quantitative
analysis, the index of attraction was calculated as
described in .
Locomotor activity assays.
Locomotor activity was
individually estimated using the open-ﬁeld method .
A ﬂy was placed in a Petri dish with a 5-mm grid drawn
on the bottom. The total way covered within 2 min of
observation was estimated. The mean way was calcu-
lated for males and females of each strain, and the rela-
tive locomotor activity (
) was used for convenience
(see the table).
RESULTS AND DISCUSSION
Analysis of the Olfactory Sensitivity
Ethylacetate and benzaldehyde have earlier been
repellents . In response to
these substances, all ﬂies, irrespective of their geno-
Some Behavioral Features of
E. A. Subocheva, L. G. Romanova, N. I. Romanova, and A. I. Kim
Department of Genetics, Moscow State University, Moscow, 119899 Russia
Received June 15, 2001
—Olfactory sensitivity and locomotor activity was assayed in
ing a mutation of the
gene, which controls transposition of retrotransposon
. A change in olfac-
tory sensitivity was detected. The reaction to the odor of acetic acid was inverted in ﬂies of the mutator strain
(MS), which carried the
mutation and active
copies and were characterized by genetic instability.
Flies of the genetically unstable strains displayed a lower locomotor activity. The behavioral changes in MS ﬂies
can be explained by the pleiotropic effect of the
mutation or by insertion mutations which arise in behavior
genes as a result of genome destabilization by