The spatial distribution of sensory bristles on the notum of different species of Diptera is compared. Species displaying ancestral features have a simple organization of randomly distributed, but uniformly spaced, bristles, whereas species thought to be more derived bear patterns in which the bristles are aligned into longitudinal rows. The number of rows of large bristles on the scutum was probably restricted to four early on in the evolution of cyclorraphous Brachyceran flies. Most species have stereotyped patterns based on modifications of these four rows. The possible constraints placed upon the patterning mechanisms due to growth and moulting within the Diptera are discussed, as well as within hemimetabolous insects. The holometabolic life cycle and the setting aside of groups of imaginal cells whose function is not required during the growth period, may have provided the freedom necessary for the evolution of elaborate bristle patterns. We briefly review the current state of knowledge concerning the complex genetic pathways regulating achaete-scute gene expression and bristle pattern in Drosophila melanogaster, and consider mechanisms for the genetic regulation of the bristle patterns of other species of Diptera.

Reference

Artavanis-Tsakonas
S.
,
Matsuno
K.
,
Fortini
M.
(
1995
)
Notch signalling.
Science
268
,
225
232
Campuzano
S.
,
Modolell
J.
(
1992
)
Patterning of the Drosophila nervous system: the achaete-scute gene complex.
Trends Genet
8
,
202
208
Cubadda
Y.
,
Heitzler
P.
,
Ray
R.
,
Ramain
P.
,
Gelbart
W.
,
Simpson
P.
,
Haenlin
M.
(
1997
)
u-shaped encodes a zinc finger protein that regulates the proneural genes achaete and scute during formation of bristles in Drosophila.
Genes Dev
11
,
3083
3095
Cubas
P.
,
de Celis
J.-F.
,
Campuzano
S.
,
Modolell
J.
(
1991
)
Proneural clusters of achaete/scute expression and the generation of sensory organs in the Drosophila imaginal wing disc.
Genes Dev
5
,
996
1008
Cubas
P.
,
Modolell
J.
(
1992
)
The extramacrochaetae gene provides information for sensory organ patterning.
EMBO J
11
,
3385
3393
Dickinson
M.
,
Palka
J.
(
1987
)
Physiological properties, time of development and central projection are correlated in the wing mechanoreceptors of Drosophila.
J. Neuroscience
7
,
4201
4208
Dickinson
M.
,
Hannaford
S.
,
Palka
J.
(
1997
)
The evolution of insect wings and their sensory apparatus.
Brain, Behav. Evol
50
,
13
24
Galant
R.
,
Skeath
J. B.
,
Paddock
S.
,
Lewis
D. L.
,
Carroll
S.
(
1998
)
Expression of a butterfly achaete-scute homolog reveals the homology of butterfly wing scales and insect sensory bristles.
Curr. Biol
8
,
807
813
Garrell
J.
,
Modolell
J.
(
1990
)
The Drosophila extramacrochaetae locus, an antagonist of proneural genes that, like these genes, encodes a helix-loop-helix protein.
Cell
61
,
39
48
Ghysen
A.
(
1980
)
The projection of sensory neurons in the central nervous system of Drosophila: choice of the appropriate pathway.
Dev. Biol
78
,
521
541
Ghysen
A.
,
Dambly-Chaudiere
C.
(
1988
)
From DNA to form: the achaete-scute complex.
Genes Dev
2
,
495
501
Gomez-Skarmeta
J. L.
,
Rodriguez
I.
,
Martinez
C.
,
Culi
J.
,
Ferres-Marco
D.
,
Beamonte
D.
,
Modolell
J.
(
1995
)
Cis -regulation of achaete and scute: shared enhancer-like elements drive their coexpression in proneural clusters of the imaginal discs.
Genes Dev
9
,
1869
1882
Gomez-Skarmeta
J. L.
,
del Corral
R. D.
,
de la Calle-Mustienes
E.
,
Ferre-Marco
D.
,
Modolell
J.
(
1996
)
araucan and caupolican, two members of the novel iroquois complex, encode homeoproteins that control proneural and vein-forming genes.
Cell
85
,
95
105
Gonzalez
F.
,
Romani
S.
,
Cubas
P.
,
Modolell
J.
,
Campuzano
S.
(
1989
)
Molecular analysis of the asense gene, a member of the achaete-scute complex of Drosophila melanogaster, and its novel role in optic lobe development.
EMBO J
8
,
3553
3562
Hartenstein
V.
,
Posakony
J.
(
1990
)
A dual function of the Notch gene in Drosophila sensillum development.
Dev. Biol
142
,
13
20
Heitzler
P.
,
Bourouis
M.
,
Ruel
L.
,
Carteret
C.
,
Simpson
P.
(
1996
)
Genes of the Enhancer of split and achaete-scute complexes are required for a regulatory loop between Notch and Delta during lateral signalling in Drosophila.
Development
122
,
161
171
Hinz
U.
,
Giebel
B.
,
Campos-Ortega
J.
(
1994
)
The basic HLH domain of Drosophila lethal of scute protein is sufficient for proneural function and activates neurogenic genes.
Cell
76
,
77
87
Huang
F.
,
Dambly-Chaudiere
C.
,
Ghysen
A.
(
1991
)
The emergence of sense organs in the wing disc of Drosophila.
Development
111
,
1087
1095
Kimble
J.
,
Simpson
P.
(
1997
)
The LIN-12/Notch signalling pathway and its regulation.
Ann. Rev. Cell Dev. Biol
13
,
333
361
Kondo
S.
,
Asai
R.
(
1995
)
A reaction-diffusion wave on the skin of marine angelfish Pomacanthus.
Nature
376
,
765
768
Kooh
P. J.
,
Fehon
R. G.
,
Muskavitch
M. A. T.
(
1993
)
Implications of dynamic patterns of Delta and Notch expression for cellular interactions during Drosophila development.
Development
117
,
493
507
Lawrence
P. A.
,
Struhl
G.
(
1996
)
Morphogens, compartments, and pattern: lessons from Drosophila?.
Cell
85
,
951
961
Leyns
L.
,
Gomez-Skarmeta
J.-L.
,
Dambly-Chaudiere
C.
(
1996
)
iroquois: a prepattern gene that controls the formation of bristles on the thorax of Drosophila.
Mech. Dev
59
,
63
72
Meinhardt
H.
(
1995
)
Dynamics of stripe formation.
Nature
376
,
722
–.
Ohsako
S.
,
Hyer
J.
,
Panganiban
G.
,
Oliver
I.
,
Caudy
M.
(
1994
)
hairy function as a DNA-binding helix-loop-helix repressor of Drosophila sensory organ formation.
Genes Dev
8
,
2743
2755
Orenic
T. V.
,
Held
L.
Jr
,
Paddock
S.
,
Carroll
S.
(
1993
)
The spatial organization of epidermal structures: hairy establishes the geometrical pattern of Drosophila leg bristles by delimiting the domains of achaete expression.
Development
118
,
9
20
Phillips
R. G.
,
Whittle
J. R.
(
1993
)
wingless expression mediates determination of peripheral nervous system elements in late stages of Drosophila wing disc development.
Development
118
,
427
438
Ramain
P.
,
Heitzler
P.
,
Haenlin
M.
,
Simpson
P.
(
1993
)
pannier, a negative regulator of achaete and scute in Drosophila, encodes a zinc finger protein with homology to the vertebrate transcription factor GATA-1.
Development
119
,
1277
1291
Rodriguez
I.
,
Hernandez
R.
,
Modolell
J.
,
Ruiz-Gomez
M.
(
1990
)
Competence to develop sensory organs is temporally and spatially regulated in Drosophila epidermis.
EMBO J
9
,
3583
3592
Rushlow
C. A.
,
Hogan
A.
,
Pinchin
S. M.
,
Howe
K. M.
,
Lardelli
M.
,
Ish-Horowicz
D.
(
1989
)
The Drosophilahairy protein acts in both segmentation and bristle patterning and shows homology to N-myc.
EMBO J
8
,
3095
3103
Ruiz-Gomez
M.
,
Modolell
J.
(
1987
)
Deletion analysis of the achaete-scute locus of Drosophila melanogaster.
Genes Dev
1
,
1238
1246
Seydoux
G.
,
Greenwald
I.
(
1989
)
Cell autonomy of lin-12 function in a cell fate decision in C. elegans.
Cell
57
,
1237
1245
Simpson
P.
(
1996
)
Drosophila development: A prepattern for sensory bristles.
Curr. Biol
6
,
948
950
Simpson
P.
,
Morata
G.
(
1981
)
Differential mitotic rates and patterns of growth in compartments in the Drosophila wing.
Dev. Biol
85
,
299
308
Skeath
J. B.
,
Carroll
S. B.
(
1991
)
Regulation of achaete-scute gene expression and sensory organ pattern formation in the Drosophila wing.
Genes Dev
5
,
984
995
Stern
C.
(
1954
)
Two or three bristles.
Am. Scient
42
,
213
247
Sturtevant
A. H.
(
1970
)
Studies on the bristle pattern of Drosophila.
Dev. Biol
21
,
48
61
Van Doren
M.
,
Ellis
H. M.
,
Posakony
J.
(
1991
)
The Drosophila extramacrochaete protein antagonizes sequence-specific DNA-binding by daughterless/achaete-scute protein complexes.
Development
113
,
245
255
Wigglesworth
V. B.
(
1940
)
Local and general factors in the development of ‘pattern’ in Rhodnius prolixus (Hemiptera).
J. Exp. Biol
17
,
180
200
Wilkinson
H. A.
,
Fitzgerald
K.
,
Greenwald
I.
(
1994
)
Reciprocal changes in expression of the receptor lin-12 and its ligand lag-2 prior to commitment in a C. elegans cell fate decision.
Cell
79
,
1187
1198
This content is only available via PDF.