|Feature type||allele||Associated gene||Dmel\Egfr|
|Also Known As||EGFRts, Egfrts1a|
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Controlled Vocabulary Terms
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|Nature of the Allele|
|Mutations Mapped to the Genome|
|Associated Sequence Data|
|Nature of the lesion|
Amino acid replacement: S511F.
Nucleotide substitution: C1754T.
|Phenotype Manifest In|
mitotic cell cycle & eye disc
In stage 16 Egfr[tsla]/Egfr[f24] embryos the two neurons that normally arise closest to the midline are lost, vdaB (in 79% of cases) and the class III neurons (in 76% of cases). Loss of these neurons are preceded by the loss of SOPs 1a (73%() and 1 (69%).
The cardiac function of Egfr[f24]/Egfr[tsla] flies is similar to that of wild-type controls at 18[o]C. The cardiac function of Egfr[f24]/Egfr[tsla] flies deteriorates after 24 h at 25[o]C.
Marker expression analysis shows that in Egfr[tsla]/Egfr[f24] flies heat shocked for 24 hours at the beginning of pupariation, the proportion of pale-ommatidia is reduced and hybrid ommatidia are present with a yellow-type R8 and a pale-type R7. These animals have very rough eyes.
Primordial germ cells overproliferate in Egfrtsla/Egfrf24 larvae grown at a restrictive temperature. Fewer intermingled cells (somatic cells adjacent to primordial germ cells) are present in Egfrtsla/Egfrf24 gonads compared to wild-type.
At the restrictive temperature, additional cells enter the second mitotic wave in Egfr[tsla] eye discs.
Complete posterior spiracles are present in Egfrtsla embryos that have been maintained at the restrictive temperature from 5-8 hours of development despite severe segment polarity defects.
Egfrtsla protein is wild-type at 18oC for ligand-dependent signalling activity. However, at 30oC its activity is very low, and is indistinguishable from no activity at all. The Egfrtsla protein undergoes a ligand-independent conformational change at 30oC, leading to rapid internalisation. R8 cells form in Egfrtsla eye mutant clones, although at later stages they are sometimes abnormally close. Egfrtsla mutant clones do not exhibit any changes in morphogenetic furrow progression, compared to wild-type clones. Egfrtsla has no effect on R8/founder cell initial spacing, neither with a 24-hour shift, nor when raised continuously at the non-permissive temperature.
Egfrtsla/Egfrf24 animals shifted to restrictive temperatures for 24 hours during the first half of the third larval instar have leg truncations, with the size of the truncation increasing with temperature. At lower restrictive temperatures (28.7oC) only the most distal structures (the claws) are missing but at high temperatures (33oC) structures tarsal segments 2-5 are absent. At 33oC development of regions more proximal to the tarsal segments is occasionally disrupted. Egfrtsla/Egfrf24 clones do not survive in distal regions of the leg disc at temperatures above 31oC. Egfrtsla/Egfrf24 animals shifted to 33oC for 12 hours during the first quarter of the third larval instar show truncations of the tarsus. However, a 12 hour shift during the second quarter of the third larval instar results in legs with normal distal elements (claw and tarsal segment 5) but fusions or deletions of the intermediate tarsal segments 2-4.
When Egfrtsla/Egfrf24 mutants are grown at the permissive temperature (18oC) throughout larval development, and then shifted to the non-permissive temperature (29oC) between 0 and 10 hours after puparium formation (APF) recognizable transverse rows (t-rows) of bristles are seen on the basitarsus and distal tibia are seen, but bristles within each row are jumbled in irregular groups. (bristles line up, with sockets touching in wild-type). Up shifts after 10h APF have little effect. When these mutants are grown at 18oC throughout larval development, shifted up to 29oCat pupariation and shifted back down between 0 and 14 hours APF, little effect is seen. Down shifts after 21h APF cause disruption of the organisation of the t-rows. When downshifts occur between 14 and 20h APF, other phenotypes emerge. In a minority of legs (13%) adjacent rows bend toward one another and join at Y or X shaped intersections.
When Egfrtsla/Egfrf24 animals are raised at the permissive temperature (of 18oC) they have a wild-type pattern of bracts. Those raised at 29oC lack all bracts. The sensitive period for tibial and basitarsal bracts are 17-28h and 13-28h AP respectively.
Egfrtsla clones induced in the wing disc in a Minute background after the mid-second instar (and maintained at the restrictive temperature of 31oC) can contribute to the prospective lateral notum, albeit rarely. Clones in the prospective lateral notum are abnormally round in shape. Egfrtsla clones in the wing disc maintained at 28oC can be recovered in the prospective lateral notum, even when induced during the first larval instar. Homozygous clones generated before the second larval instar and maintained at the permissive temperature of 25oC can contribute to either or both of the dorsal and ventral compartments of the wing disc. However, there is an enhanced tendency for the clones to occupy the ventral compartment as the clones are maintained at more restrictive temperatures.
Egfrtsla cells in the eye disc arrest in G2 at the restrictive temperature even when adjacent to preclusters of differentiating photoreceptor cells. The only cells not to enter the second mitotic wave are differentiating R8 cells. At the restrictive temperature, undifferentiated cells around the ommatidia in the developing eye disc adopt a typical apoptotic morphology. As the morphogenetic furrow progresses, apoptotic cells disappear from posterior regions, and new regions of the disc are brought into the region where cells die. Cell death is also seen in other tissues, including the eye disc anterior to the morphogenetic furrow.
Egfrtsla/Egfrf24 flies at 18oC frequently lack the anterior supraalar bristle, posterior supraalar bristle and posterior postalar bristle, and the anterior postalar bristle and anterior dorsocentral bristle are frequently duplicated. When late LIII larvae are shifted to 30oC for 15 hours, all notum macrochaetae show reduced liklihood to develop except the scutellar bristles.
Egfrf24/Egfrtsla embryos raised at 18oC until approximately stage 12, and then shifted to 29oC for the remainder of development exhibit reduced numbers and increased apoptosis of longitudinal (interface) glial cells.
Egfrf24/Egfrtsla animals kept at the restrictive temperature between 168-180 hours after egg deposition (AED) develop an adult eye that lacks ommatidia. Imaginal discs from these animals examined at either 192 or 204 hours AED lack both the ommatidia and the morphogenetic furrow. Egfrf24/Egfrtsla animals kept at the restrictive temperature between 192-204 hours AED develop an eye with severe structural defects along the posterior-lateral margins (ommatidia at the intersection of the equator and posterior margin appear not to be affected). The morphogenetic furrow has clearly initiated at the posterior margin in imaginal discs from these animals examined at 204 hours AED, but its continued re-initiation along the lateral margins is inhibited.
If Egfrtsla/Egfrf24 flies are raised at 17oC, transferred to 25oC for 24 hours at second instar larval stages, and then returned to 17oC leads to a mirror image duplication of the wing.
When Egfrtsla/Egfrf24 mutant males are raised at the permissive temperature (18oC), and then shifted to the restrictive temperature (29oC), a spermatogenesis phenotype is seen. Although all stages of spermatogenesis are initially present, by one week of at non-permissive temperature, testes are filled with massive numbers of early germ cells with small nuclei. The early germ cells appear to proliferate at the expense of differentiation, as spermatocytes and spermatids are absent or markedly reduced in numbers. Many early germ cells displayed expression marker, subcellular structures and cell division behaviour characteristic of stem cells and gonialblasts. Mutants have many more cells with ball shaped or dumbbell-shaped spectrosomes, both near the tip and displaced down the testis. In Egfrtsla/Egfrf24 mutant males, early cyst cells often form improper associations with early germ cells. In general accumulation of early germ cells is not associated with a corresponding increase in the total number of cyst progenitor or early cyst cells.
When Egfrtsla/Egfrf24 flies are grown at the restrictive temperature for Egfrtsla during the second instar, the notum is lost, the wings are present but have pattern abnormalities and fail to inflate.
The notum is significantly reduced in size in Egfrtsla/Egfrt1 wing discs raised at the non-permissive temperature.
Temperature sensitive mutation; at 18oC the cuticle of Egfrtsla/Egfrf24 embryos is indistinguishable from wild-type, and at 28oC the cuticle of Egfrtsla/Egfrf24 embryos is indistinguishable from that of Egfrf24/Egfrf24 homozygotes. Suppresses the dominant EgfrE1 phenotype towards wild-type in transheterozygotes at 28oC but does not suppress the dominant EgfrE1 phenotype at 18oC. Egfrtsla/Egfrf24 animals raised at the non-permissive temperature for 24 hours in late larval life and then returned to 18oC have eye defects, including a physical scar running across the eye in a dorsal to ventral direction. Egfrtsla/Egfrf24 larvae raised at 18oC and then placed at 28oC for 24 hours show few effects on ommatidial cluster formation in and close to the morphogenetic furrow of the eye disc, but the clusters five or six columns posterior to the furrow are dysmorphic. Egfrtsla/Egfrf24 larvae raised at 18oC and then shifted to 28oC at a slightly earlier time, when the morphogenetic furrow is not yet initiated, show an inhibition of neural differentiation at the posterior margin but not at the dorsal or ventral margins of the eye disc.
|Phenotype Manifest In|
|Complementation & Rescue Data|
|Stocks ( 1 )|
|Notes on Origin|
|External Crossreferences & Linkouts|
|Synonyms & Secondary IDs ( 15 )|
|Secondary FlyBase IDs|
|References ( 39 )|
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|Recent research papers ( 3 )|