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General Information
D. melanogaster
FlyBase ID
Feature type
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
sevd2, sev0
Key Links
Nature of the Allele
Mutations Mapped to the Genome
Additional Notes
Associated Sequence Data
DNA sequence
Protein sequence
Progenitor genotype
Nature of the lesion
Expression Data
Reporter Expression
Additional Information
Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 0 )
Modifiers Based on Experimental Evidence ( 0 )
Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
Disease-implicated variant(s)
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description

sev14 eyes exhibit reduced number of Rh5 expressing R8 cells.

In the sev14 mutant eye, R7 photoreceptors are not formed; columns are disorganized in the larval and pupal medulla (disorganization in M4-M5 and M9-M10 layers, but not M1-M2 layers); unlike controls, the bifurcated Mi1 axon terminals are separated and split apart; importantly, the abnormal columns and Mi1 axon terminals are observed in the layers to which the R7 axon does not project.

sev14 eye clones display a loss of R7 photoreceptors, with the central rhabdomeres noticeably absent.

sev14 mosaic eye clones exhibit fewer R1 cells and an increase in R6 photoreceptor cells.

sev14 flies carrying sevΔ22 lack R7 photoreceptor cells in 10% of ommatidia.

sev14 homozygotes have decreased numbers of pale ommatidia (as judged by R8 marker expression).

Mutants completely lack photoreceptor cell R7 axons. The photoreceptor cell R8 axons develop normally until the adult stage in these mutants, showing normal targeting.

R7 cells are absent in sev14 ommatidia.

sev14 eyes show a loss of pR8 photoreceptors.

sev14 mutants lack R7 photoreceptor cells. However, the R8 and L1-L5 axons target correctly to their temporary layers in the medulla.

Ommatidia lack R7 cells.

sev14 flies lack R7 photoreceptors.

Homozygous ommatidia have no R7 photoreceptors.

Homozygotes lack R7 photoreceptor cells.

Su(Raf) Hsp83 mutations and Hsp83e6D interact genetically with the sev mutations, other E(sev) Hsp83 mutations fail to interact.

R7 precursor never develops into a mature R7 cell.

Transheterozygotes with argos257 fail to restore the production of R7 cells.

sev14 mutants partially rescued by sevY1485A.W1486A.sev are referred to as 'sev351' flies. 'sev351' flies exhibit reduction in numbers of R7 cells per ommatidium. This phenotype is dominantly enhanced by phyl mutants.

Neither SosNCatC.hs.sev nor SosNCat.hs.sev has any effect on R7 cell development in sev14/Y flies. No R7 cells develop.

Apical localization of protein encoded by bossEX lost in sev14 mutant eyes.

Mutant phenotype rescued by chimeric D.virilis : D.melanogaster sev+ construct: 100% of ommatidia have R7 cells, and R7-specific Rh4 gene expression correlates with R7 cell rescue.

R7 precursor cell develops into an equatorial cone cell (EQC). P{HZ}klgH214 marker expression is present in R7 precursor cell and persists in the EQC.

Ommatidia lack R7 photoreceptors. Flies are attracted preferentially toward green light. sev14, sevS11.T:Hsap\MYC flies are attracted to UV light suggesting that some of the supernumerary R7-like cells make functional synaptic connections.

Double mutant sev14; bossHSB adult eye completely lacks R7 cells.

Ommatidia lack R7 photoreceptor cells.

positive phototaxis with Ppb/+

External Data
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Phenotype Manifest In
Enhanced by
Suppressed by
NOT suppressed by

sev14 has pale ommatidium phenotype, non-suppressible by rhoGMR.Exel

NOT Enhancer of
Suppressor of
NOT Suppressor of
Additional Comments
Genetic Interactions

The presence of RV12.hs2sev in a sev14 homozygous background suppresses the R7 photoreceptor loss seen in sev14 mutants.

Introduction of RV12.hs2sev clones in sev14 eye tissue results in normally constructed ommatidia (containing a single R7 at their centre). The R7 cells in these ommatidia are invariably pigmented (indicating the presence of RV12.hs2sev) and demonstrate the cell-autonomous rescue of sev14 in the R7 precursor by activated R.

n a sev14; Nact.sev double mutant background, R1/R6 cells differentiate as cone cells, and, in the adult eyes only large rhabdomere cells are evident in the outer regions (R7 level) of the eye. Thus, removal of sev from Nact.sev ommatidia presents the specification of the R1/R6 cells as photoreceptors.

Homozygosity for Socs36EEY11 partially suppresses the loss of photoreceptor cells R7 seen in sev14 flies carrying sevΔ22 (only 2% of ommatidia are missing the R7 cell in the double mutant flies).

The decreased number of pale ommatidia in sev14 homozygotes (as judged by R8 marker expression), is not suppressed by rhoGMR.Exel.

In EgfrE1/+ adults, the number of ommatidia with pale-type R8 cells and yellow-type R7 cells is significantly increased. Many of these are found in pale-yellow hybrid ommatidia with a yellow-type R7 and a pale-type R8. This phenotype is suppressed by sev14/sev14 .

The average number of total R cells in sev14, CblK26 mutant ommatidia is 11.12, containing more than four R7 cells per ommatidium.

sev14; wtsP1 eyes show the same phenotype as wtsP1 eyes, with all R8 cells being specified as the p subtype. sev14; Df(3L)melt-Δ3, wtsP1 triple mutants also show the wtsP1 phenotype.

Eyes that express meltScer\UAS.cTa, under the control of Scer\GAL4GMR.long, in a sev14 background, have a high proportion of pR8 photoreceptors and a small proportion of yR8 receptors.

sev14/da2 double heterozygous females do not have follicular defects in the ovary.

Many R7 cells differentiate in sev14 flies expressing atoScer\UAS.cJa under the control of Scer\GAL4sca-109-68. This rescue of R7 formation by atoScer\UAS.cJa expressed under the control of Scer\GAL4sca-109-68 is strongly suppressed if the flies are also carrying Egfrf3.

R7 cells do form in sev14 ; styS73 double mutant ommatidia. In mosaic ommatidia, the only cell that needs to be mutant for styS73 for an R7 cell to form is the R7 cell itself.

sev14 significantly suppresses the formation of extra outer photoreceptors caused by B-H1sev.PH.

Double mutants of sl1 or sl2 with either sev1 or sev14 show a mutant phenotype intermediate to that of either single mutant: 35-49% of ommatidia have one R7 cell, 6-12% contain two R7 cells and the rest have no R7 cells.

The R8 rhabdomere projects more apically, assuming the position of the R7 rhabdomere, when klgScer\UAS.cBa is expressed using Scer\GAL4elav-C155 in a sev14 background.

60% of sev14 ; fafBX4 double homozygous ommatidia have an R7 cell.

The presence of the P{sevRas1.V12} construct rescues the R7 precursor from transformation into a cone cell and induces the formation of supernumerary R7 cells.

Ommatidia of double mutants with Gap1B2 show multiple R7 cells. Homozygous mutant phenotype can be suppressed by Gap1B1, Gap1B2, Gap1B3, Gap1B4 or Gap1B5, R7 cells are present within the ommatidia.

SosJC2 does not suppress the mutant phenotype, R7 cells are absent from ommatidia.

Xenogenetic Interactions
Complementation and Rescue Data
Partially rescued by
Not rescued by

sev14 is not rescued by sevint1

sev14 is not rescued by sevmA

sev14 is not rescued by sevmB


'sev315' flies are sev14 mutants partially rescued by sevY1485A.W1486A.sev.

sev14; P{sE-torso4021-sev}/P{sE-torso4021-sev} flies exhibit R7 cells in many ommatidia.

sev14 mutants partially rescued by sevY1485A.W1486A.sev are referred to as 'sev351' flies.

Heat shock every 4 hours for 30 minutes starting 24 hours before and lasting 12 hours after the white prepupal stage can completely rescue the sev14 mutant phenotype. Heat shock every 8 hours causes a minor portion of ommatidia lacking R7 cells, heat shock every 12 hours causes well defined stripes of sev- ommatidia and wild type ommatidia.

Mutant phenotype can be completely rescued by sevhs.PBa after heat shock every 6 hours for 30 minutes. Heat shock every 12 hours causes alternating stripes of sev- ommatidia and wild type ommatidia.

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Stocks (8)
Notes on Origin

Gerresheim, 1988.


sev14 flies carrying rosev.PI have no R7 photoreceptor cell, indicating that ro is unable to bypass the requirement for sev function to specify neuronal fate in the R7 precursor cell.

External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (4)
Reported As
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Secondary FlyBase IDs
    References (79)