Phenotypes of various orb mutants
. | Chorion phenotype . | . | . | |||
|---|---|---|---|---|---|---|
| Genotype . | Wild type . | DV defects . | % DV defect (type) . | |||
| (A) | ||||||
| w1 | 3818 | 110 | 2.8 (ventralized) | |||
| K(10)/K(10 | 0 | 1223 | 100 (dorsalized) | |||
| orbmel/orbmel | 5 | 43 | 89.6 (ventralized) | |||
| K(10)/K(10); orbmel/orbmel | 1 | 643 | 98.4 (dorsalized) | |||
| (B) | ||||||
| w1 | 937 | 15 | 1.9 (ventralized) | |||
| Hd19G,orbere; Tm3Ser | 493 | 122 | 19.8 (ventralized) | |||
| K(10)/+; Hd19G orb343 | 1374 | 178 | 11.5 (ventralized) | |||
| Six females flies of the indicated genotype were placed on apple juice-agar plates with yeast for 24 hours at 22-23°C. | ||||||
. | Chorion phenotype . | . | . | |||
|---|---|---|---|---|---|---|
| Genotype . | Wild type . | DV defects . | % DV defect (type) . | |||
| (A) | ||||||
| w1 | 3818 | 110 | 2.8 (ventralized) | |||
| K(10)/K(10 | 0 | 1223 | 100 (dorsalized) | |||
| orbmel/orbmel | 5 | 43 | 89.6 (ventralized) | |||
| K(10)/K(10); orbmel/orbmel | 1 | 643 | 98.4 (dorsalized) | |||
| (B) | ||||||
| w1 | 937 | 15 | 1.9 (ventralized) | |||
| Hd19G,orbere; Tm3Ser | 493 | 122 | 19.8 (ventralized) | |||
| K(10)/+; Hd19G orb343 | 1374 | 178 | 11.5 (ventralized) | |||
| Six females flies of the indicated genotype were placed on apple juice-agar plates with yeast for 24 hours at 22-23°C. | ||||||
K(10) suppresses the dorsoventral defects associated withorb mutants. Eggs laid by w1, orbmel,K(10) and the K(10); orbmel double mutant were examined and scored for chorion defects. The w1 strain present in the laboratory shows a background level of 1-3% ventralized eggs.
The K(10) mutation weakly suppresses the chorion defects induced by reduced Orb protein expression. The Hd19G transgene insert on the third chromosome has the orb 3′ UTR fused to lacZprotein coding sequences. Expression of this hybrid mRNA in ovaries is driven by the hsp83 promoter. The hsp83:lacZ orb 3′ UTR transgene, Hd19G, is a dominant negative and interferes withorb autoregulation (Tan et al.,2001). Approximately 20% of the eggs produced by orb343/+ females carrying a single copy of the Hd19G transgene are ventralized. The percentage of ventralized eggs dropped from 20% in the Hd19G, orb343/+strain to 12% when the females are also heterozygous for the K(10)mutation.