Biology Reference
In-Depth Information
radish
,
amnesiac
,
cabbage
,
latheo
and
linotte
, are involved in abnormal learn-
ing or memory of
D. melanogaster
(
Table 11.3
). For example, flies with the
X-linked
radish
mutation initially learn in olfactory tests, but their subsequent
memory decays rapidly at both early and late times after learning. The
radish
flies show normal locomotor activity and sensitivity to odor cues and electric-
shock reinforcements used in the learning tests. Anesthesia-resistant memory,
or consolidated memory, is strongly reduced in
D. melanogaster
with the
radish
phenotype (
Folkers et al. 1993
).
The
rutabaga
+
gene codes for an adenyl cyclase and is expressed in
Drosophila
mushroom bodies. This gene is involved in olfactory short-term memory (
Zars
et al. 2000
). Likewise,
Volado
+
is expressed in mushroom body cells of
Drosophila
and mediates short-term memory in olfactory learning (
Grotewiel et al. 1998
).
How does long-term memory develop and persist over years?
Majumdar et al.
(2012)
found that the
Drosophila
Orb2 protein forms amyloid-like oligomers
upon neuronal stimulation and these are enriched in the synaptic membrane,
which may be critical for the persistence of long-term memory. Mutants of the
Orb2 protein had impaired long-term memories, suggesting that self-sustaining
amyloid-like conversion of the neuronal cytoplasmic polyadenylation element-
binding proteins (CPED) is involved in long-term memory lasting
>
12 hours.
The enlightenment obtained from the study of
Drosophila
learning mutants
is providing an understanding of learning in higher organisms (
Tully 1991a,b,
1996, Dubnau and Tully 1998, Sokolowski 2001, Waddell and Quinn 2001,
Majumdar et al. 2012
).
11.5.3 Functional Genomics of Odor Behavior in
Drosophila
The ability to respond to odors is essential for survival and reproduction, allow-
ing insects to select mates, find and choose food, and locate appropriate ovipo-
sition sites. Insects detect odors with antennae and maxillary palps, upon which
sensory hairs (sensilla) are present. Each sensillum houses the dendrites of a few
olfactory-receptor neurons. Insect antennae can contain
>
100,000 sensilla but
D. melanogaster
antennas contain
≈
400 sensilla. Sexual dimorphism in antennal
structure is common in insects, and immature insects typically have fewer sen-
silla than adults, perhaps because insect eggs typically are deposited in or near
the appropriate food for the larvae.
Studies of the genetic basis of odor behavior in insects first used
D. melano-
gaster
as a model system (
Field et al. 2000, Vosshall 2000, Anholt et al. 2001
).
Efforts also are being made to evaluate olfaction, learning, and memory in
the honey bee (
Maleszka 2000, Robertson and Wanner 2006
).
Robertson and
