From Bridges and Brehme, 1944, Carnegie Inst. Washington Publ.
No. 552: 12.
ac specifies the formation of the anterior and posterior dorsocentral, the posterior supra-alar (as does sc),
the anterior vertical bristle, and in addition the acrostichal
rows of microchaetae on the notum. Absence of bristles accompanied by absence of associated socket and underlying centrally projecting neuron (Stern, 1938, Genetics 23: 172-73).
In addition mutant alleles of ac tend to remove the interocellar hairs and the hairs on the surface of the eye and a restricted subset of the campaniform sensilla on the wing blade
(Leyns, Dambly-Chaudiere and Ghysen, 1989, Roux's Arch. Dev.
Biol. 198: 227-32). Trichomes are not affected. ac deficiencies, e.g., In(1)y3PLsc8R, survive as fully mobile and
fertile adults (Garcia-Bellido, 1979, Genetics 90: 491-529).
A series of terminal deficiencies approaching the ac coding
sequence from the left a few hundred base pairs at a time,
when tested in heterozygotes with In(1)y3PLsc8R or Df(1)sc19,
cause, with few exceptions, progressive loss of chaetae as the
amount of deleted material increases; response of anterior
verticals erratic. First effects of deficiencies noted with
chromosomes broken 10 kb upstream of the transcription start
site. Despite loss of most of the DNA upstream from the transcribed region, the phenotypes associated with these deletions
still suppressed by emc and h (Ruiz-Gomez and Modolell, 1987,
Genes Dev. 1: 1238-46). Deficiencies for ac act as suppressors of h (Sturtevant, 1970, Dev. Biol. 21: 48-63), whereas
extra doses of ac+ enhance expression of h (Moscoso del Prado
and Garcia-Bellido, 1984, Wilhelm Roux's Arch. Dev. Biol.
193: 242-51). Longitudinal stripes of expression on either
side of the midline during gastrulation become internalized
and segmented into four longitudinal rows of clusters of
expressing cells at half-segment intervals. ac RNA undetectable in germ band at time of germ-band shortening. Several
regions of high expression seen in cephalic region. Also
expressed in posterior midgut rudiment (Romani, Campuzano, and
Modolell, 1987, EMBO J. 6: 2085-92; Cabrera, Martinez-Arias,
and Bate, 1987, Cell 50: 425-33). In third-instar larvae,
expression in wing imaginal disks restricted to regions where
precursors of cuticular organs specified by ac are known to
reside (Romani, Campuzano, Macagno, and Modolell, 1989, Genes
Dev. 3: 997-1007).
Hypomorphic; phenotype of homozygous females weaker
than in hemizygous females (Garcia-Bellido, 1979, Genetics
91: 491-520). Posterior dorsocentral bristles missing; also
posterior supra-alar and anterior vertical bristles frequently
missing. Anterior dorsocentrals displaced anteriorly (Claxton,
1969, Genetics 63: 883-96). Garcia-Bellido (1979) finds
anterior dorsocentral bristles more strongly decreased than
posterior dorsocentrals. Hairs usually fewer near position of
posterior dorsocentrals; interocellar hairs invariably fewer,
typically absent. Eyes partly devoid of hairs. Trichomes
unaffected. Limited nonautonomy near the borders of somatic
spots with respect both to numbers and positions of bristles
and hairs (Stern, 1954, Am. Sci. 42: 212-47; Roberts, 1961,
Genetics 46: 1241-43; Claxton, 1976, Genet. Res. 27: 11-22).
ac partially suppresses h; Hw/ac = Hw/+ (Sturtevant, 1969).
Since ac2 and sc3 were for practical purposes
inseparable by crossing over, the effect of ac2 alone could
not be assessed. The double mutant removed all bristles
except scutellars and postdorsocentrals. ac2/ac2 and ac2/+
suppress h (Sturtevant). Viability of males low; females
nearly inviable. RK2.
Posterior and usually anterior dorsocentrals lacking; other bristles wild type. Hairs removed from areas
across rear and front edges of thorax, through mid-dorsal
area, and between ocelli. ac3 even in ac3/+ heterozygotes
exerts strong suppression on h (Sturtevant, 1970, Dev. Biol.
21: 48-61). RK2A.
Low level of absence of dorsocentral bristles as
well as microchaetae. Bristles normally removed by sc mutations not missing.
Males and heterozygous females have extra bristles
on the head (especially occipitals), the notum and the mesopleurae; also extra bristles, including sensory ones and campaniform sensilla (Palka, Schubiger, and Hart, 1981, Nature
294: 447-49), along longitudinal veins and in membrane of
wing. Classifiable in a single dose in triploids (Schultz,
1934, DIS 1: 55). Homozygous females more extreme; 110 extra
chaetae on wing vs. 49.5 for Hw1/+; 11 on scutellum and postnotum vs. 0.7 in Hw/+ (Garcia-Bellido and Merriam, 1971, Proc.
Nat. Acad. Sci. USA 68: 2222-26). Number of extra bristles
inversely correlated with temperature (Ohn and Sheldon, 1970,
Genetics 66: 517-40). Hw1/Hw1 females exhibit 40-80% wildtype viability and are agametic steriles; clones of homozygous
germinal cells in Hw/+ females capable of producing progeny
(Garcia-Bellido and Robbins, 1983, Genetics 103: 235-47);
however, Garcia-Alonzo and Garcia-Bellido claim that their
strain is no longer homozygous female sterile. Viability and
fertility of Hw1/Y males and Hw1/+ females good. Hw1/Hw1 and _
autonomous in somatic clones until 8 hr before puparium formation; altering cellular genotype after that time is without
effect owing to perdurance (Garcia-Bellido and Merriam). X-ray-induced full and partial revertants are frequently mutant
for ac (Garcia-Alonzo and Garcia-Bellido). RK1 as male or
Females homozygous for Hw2 show only occasional
extra hairs along wings. Overlaps wild type. RK3A.
More extreme than Hw1. Homozygous female has doubling and tripling of many bristles, three or four extra dorsocentral bristles per side, extra wing veins, gap in posterior crossvein, and extra hairs on vein L2 and in wing cells.
Width of mesonotum in region between dorsocentral bristles
increased leading to increased numbers of acrostichal rows as
well as extraneous extra microchaetae (Gottlieb, 1964, Genetics 49: 739-60); many lack one or more ocellar or postvertical macrochaetae (Stoddard, 1972, DIS 48: 137-38). Heterozygous female has normal bristles, extra hairs on L2 and L3 and
in wing cells, and often an extra free vein from posterior
crossvein; also extra acrostichal rows. Hw49c male much like
homozygous female but bristle duplication less extreme. Low
degree of non autonomy reported at junction between
Hw49c/Hw49c and +/+ twin spots (Gottlieb). Male and heterozygous female fertile; homozygous female sterile. Revertants of
Hw49c lose their dominant phenotypes; however they remain sc
and may exhibit a weak ac phenotype or be lethal in combination with Df(1)sc19 (Garcia-Alonzo and Garcia-Bellido). Not
suppressed by su(Hw). Hw49c and Oce act synergistically in
removing head bristles but cancel each others effects on
thorax in Hw/Oce females (Stoddard). ac, sc, and l(1)sc transcripts considerably more abundant than in wild type; also
more generally expressed in wing disks than normal (Balcells
et al.). RK1.
Df(1)Hw685/Df(1)sc19 generates lateral clusters of
microchaetae on the scutellum and promotes differentiation of
extra sensilla campaniformia on the dorsal radius of the wing,
of microchaetae or other sensilla on wing vein 3, and
occasional microchaetae on wing vein 2. Slight increases in
numbers of microchaetae on notum as well. Displays a very
weak achaete effect despite presumed homozygous deficiency for
Hwbap: Hairy wing-bristly abdominal pleura
Nearly all abdominal segments have on the pleurae
two rows of bristles, which are the same size as those on the
sternites. Mutant-bearing flies have a row of bristles arising immediately posterior to each pigment band that are
shorter than other tergite bristles.
Spontaneous derivation of Hw1 with slightly weaker
Hw: Hairy wing
Edith M. Wallace, unpublished.
Gain of function alleles of ASC, which lead to the
development of supernumerary bristles and hairs in all segments of the fly: in the prefrons, postfrons, postgena, and
occipital regions of the head; in the preepisternum, episternum, anepisternum, scutum, scutellum, postnotum, wingblade,
legs, humerus, and halteres of the thorax; and in the tergites, pleura, and sternites of the abdomen. Phenotype
suppressed by three doses of h+ (Botas, Moscoso del Prado, and
Garcia-Bellido, 1982, EMBO J. 1: 307-10) and enhanced by h,
emc, and pyd (Neel, 1941, Genetics 26: 52-58; Moscoso del
Prado and Garcia-Bellido, 1984, Wilhelm Roux's Arch Dev. Biol.
193: 242-45). Numbers of super numerary bristles reduced in
da+ hemizygotes (Dambly-Chaudiere, Ghysen, Jan and Jan, 1988,
Roux's Arch Dev. Biol. 97: 419-23).