Biology Reference
In-Depth Information
Est-5
was isolated from
D. pseudoobscura
.
Est-5
in
D. pseudoobscura
is expressed
in the eyes and hemolymph. Despite these different patterns of expression,
Est-6
and
Est-5
have similar protein products, transcripts, and DNA sequences.
When
Est-5
from
D. pseudoobscura
was cloned into a
P
element and intro-
duced into
D. melanogaster
, its activity and pattern of expression in
D. melano-
gaster
matched those of
D. pseudoobscura
, implying that regulatory elements
had been conserved since the divergence of the two species 20-46 million years
ago.
Brady and Richmond (1990)
speculated that the enzyme in the common
ancestor of these two species had a more extensive expression pattern. After
their divergence, regulatory mutations may have occurred that enhanced
Est-5
expression in the eyes of
D. pseudoobscura
, whereas mutations in
Est-6
led to
increased expression in the male ejaculatory duct of
D. melanogaster
. Thus, the
use of DNA sequence similarity to identify behavioral (and other) genes can lead
to surprises.
11.5.8 Courtship Behavior in
Drosophila
Mating behavior of
D. melanogaster
is stereotypical, with a fixed sequence of
actions that are under genetic control. Courtship involves visual stimuli, acoustic
signals, and pheromones (
Hall 1994, Yamamoto et al. 1997, Goodwin 1999, Savarit
et al. 1999, Greenspan and Ferveur 2000, Ganter et al. 2011
). Male courtship
behavior involves six elements in the following order: orienting
→
following
→
wing
vibration
→
licking
→
attempting to copulate
→
copulation.
Sexual differentiation in
Drosophila
, described in Chapter 10, is controlled by
a short cascade of regulatory genes. The expression of these regulatory genes
determines all aspects of maleness and femaleness in the soma and the central
nervous system. The genes also influence courtship behavior. Sexual behavior
is irreversibly programmed during a critical period as a result of the activity, or
inactivity, of the control gene
tra
+
. Male behavior is replaced by female behavior
when
tra
+
is expressed around the time of puparium formation (
Arthur et al.
1998
).
Other genes indirectly affect courtship behavior in
Drosophila
, including
genes that involve general behavior, visual behavior, olfaction, learning/mem-
ory genes, regulating periodicity of behavior, courtship song mutants, and
female receptivity (
Hall 1994
).
Immonen and Ritchie (2012)
analyzed how gene
expression changes in response to courtship song in
D. melanogaster
, using
microarrays and quantitative polymerase chain reaction (PCR), and identified
differentially expressed genes, some of which were up-regulated and some of
which were down-regulated. Interestingly, some immune-response genes were
