Edith M. Wallace, unpublished.
The br complementation group contains both amorphic
and hypomorphic mutant alleles; amorphic alleles cause early
prepupal developmental arrest; hypomorphic alleles cause late
pupal or pharate adult developmental arrest or are viable.
Null alleles display normal larval development but prevent
elongation and eversion of discs giving rise to appendages in
the pupal stage. Wings of the viable allele, br1, somewhat
broader than normal; about 80% of normal length, with round
full tip; crossveins closer together. Shape difference visible in middle prepupal stage immediately after eversion [Waddington, 1939, Proc. Nat. Acad. Sci. USA 25: 299-307; 1940,
J. Genet. 41: 75-139 (fig.)]. A haplo-insufficient locus in
that heterozygosity for a deficiency including the br locus
leads to a slight br phenotype (Craymer and Roy, 1980, DIS
55: 200-04); furthermore, the deficiency in combination with
br1 or br3 leads to drastic reduction in viability, especially
at 18, and an extreme phenotype among survivors, including
reduced palpi characteristic of rbp alleles, short rounded
wings with interrupted veins, and malformed third legs, i.e.,
shortened and thickened femora and tibiae as well as misshapen
basitarsi. The malformed-leg syndrome is enhanced by heterozygosity for Sb or sbd alleles (Beaton, Kiss, Fristrom, and
Fristrom, 1988, Genetics 120: 453-64). br16/+ and Df(1)S39/+
display slight dominance of br effects in the presence of
RpII215Ubl (Mortin and Lefevre, 1981, Chromosoma 82: 237-47).
So named because of its failure to complement
lethality of br and rbp mutations. Homozygotes and hemizygotes die in pupal stage; puparium formation delayed three
[l(1)2Bab3] to six [l(1)2Bab1] hr. l(1)2Bab1 pupae have normal imaginal organs, and escapers have faded wings and reduced
bristles on palpi. Prepupal lethal in combination with npr11
Die in prepupal or early pupal stage after formation
of a gas bubble. Imaginal discs fail to fuse, especially dorsally, to produce a continuous integument. Puparium formation
variably delayed: 6 hr in l(1)2Bc1, 12 hr in l(1)2Bc2, and 9
hr in l(1)2Bc3 and l(1)2Bc4. Many late ecdysone puffs both in
larvae and prepupae either absent or underdeveloped [l(1)2Bc1]
[Zhimulev, Belyaeva, and Aizenzon, 1980, Genetika (Moscow)
16: 1613-31]. l(1)2Bc1 an amorphic allele fully complements
the amorphic br5 (Kiss et al.).
Males and homozygous females display normal phenotype and viability; however, in heterozygous combination with
deficiencies or npr mutations, l(1)2Bd acts as a temperature-sensitive lethal; completely lethal at 29; at 25 or 18 most
individuals die in late pupal stage, and survivors have faded
wings, swollen abdomen, and reduced bristle number on palpi.
Hemizygous male larvae fail to pupariate, although
they survive 10-15 days after their normal sibs have pupariated. Four-day-old larvae appear normal as do their imaginal
discs; normal ecdysteroid levels achieved. Discs become
abnormal beginning on the sixth day; peripodial membrane
becomes enormously distended and highly distorted; partially
evaginated structure becomes visible in the disc lumen; do not
undergo detailed morphological changes characteristic or
metamorphosis, either in situ or in transplants into normal
larvae [Fristrom, Fekete, and Fristrom, Wilhelm Roux's Arch.
Dev. Biol. 190: 11-21 (fig.)]. Both salivary glands and fat
bodies fail to undergo histolysis in situ or in vitro. Mutant
flies able to produce ecdysone, but tissues unable to respond
normally. In gynandromorphs, the female tissue forms a
puparium, whereas npr1 male tissue remains larval; no adults
survive (Kiss, Szabad, and Major, 1978, Mol. Gen. Genet.
164: 77-83; Kiss, Bencze, Fodor, Szabad, and Fristrom, 1975,
Nature 262: 136-38). Implantation of wild-type ring glands
into npr1 larvae does not rescue pupariation; however
implanted wild-type or npr1 ring glands are able to rescue
npr3 larvae [Kiss, Szabad, Belyaeva, Zhimulev, and Major,
1980, Development and Neurobiology of Drosophila (Siddiqi,
Babu, Hall, and Hall, eds.) Plenum Press, New York and London,
pp. 163-81]. No maternal effect of either npr13 or npr14
(Perrimon, Engstrom, and Mahowald, 1984, Dev. Biol.
105: 404-14). npr16 homozygous and hemizygous larvae die
without exhibiting any sign of ecdysone-inducible puff formation; culture of slivary glands in 20-OH ecdysone produces
partial development of some early, but none of late ecdysone-inducible puffs, and extraneous puff appears at 75CD
(Belyaeva, Vlassova, Biyasheva, Kakpakov, Richards, and Zhimulev, 1981, Chromosoma 84: 207-19). npr1+ gene product also
required for regression of the intermolt 68C glue puff
[Belyaeva, et al. (npr6); Crowley, Mathers and Meyerowitz,
1984, Cell 39: 149-56 (npr3)] and for the transcription of
the three 68C glue protein genes (Crowley et al).
rbp: reduced bristles on palpus
Late pupal lethal; most animals reach the pharate
adult stage. rbp2 homozygotes and males survive with fewer
than normal bristles on the palpus; when raised at 29, females
exhibit faded wings and swollen abdomens; when raised at 18
males have faded wings. rbp2/Df(1)RA19 females virtually
lethal; females carrying rbp2 and any of the other rbp alleles
are completely viable when reared at 18, but at higher temperatures most die and escapers have reduced bristles on the
palpus, shortened bristles on the scutellum, shrivelled or
swollen abdomen shrivelled wings and eyes with crumpled surface.