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General Information
D. melanogaster
FlyBase ID
Feature type
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
nkd7E89, nkd7E
Key Links
Nature of the Allele
Mutations Mapped to the Genome
Additional Notes
Nucleotide change:


Reported nucleotide change:


Amino acid change:

Q416term | nkd-PA; Q416term | nkd-PB; Q416term | nkd-PC

Reported amino acid change:


Associated Sequence Data
DNA sequence
Protein sequence
Progenitor genotype
Nature of the lesion

Nucleotide substitution: C?T.

Amino acid replacement: Q416term.

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

embryonic epidermis & embryonic abdominal segment

Detailed Description

nkd2 homozygous or nkd2/nkd13 transheterozygous embryos exhibit defective denticle belts.

nkd2/nkd3 embryos have a strong cuticle phenotype with a severe head involution defect and widely split posterior spiracles.

Homozygous embryos show excessive specification of naked cuticle, but typically retain between one and two denticle belts.

Mutant animals exhibit separated nerve roots and dendritic fields in the embryonic motor system, as in wild type.

nkd2/nkd3 embryos have a strong cuticle phenotype; the cuticles are less than 75% of wild-type length, have two or less complete denticle bands and have an exteriorized head skeleton and noneverted spiracles.

54% of hemineuromeres have an additional NB 6-4-like cell at the normal position of the NB 7-3 cell in mutant embryos, suggesting a transformation of NB 7-3 to NB 6-4 fate.

In homozygous mutant nkd2 eyes (generated by somatic clone) the interommatidial bristles normally seen are missing from the first 3-5 ommatidial rows in from the eye margin.

The gnathal lobes are misformed in mutant embryos.

Homozygous embryos have a strong cuticle phenotype; they secrete cuticle with a fully exteriorised head skeleton, widely split filzkorper and residual denticle belts only in segment A3 and/or A5 (or no denticle belts at all), and are typically less than 75% of wild-type length. Phenotypically normal homozygous clones are seen in the wing, leg, thorax, abdomen, haltere and eye. Homozygous and control clones appear with similar frequency in each leg quadrant.

Homozygous embryos have excess naked cuticle replacing denticle belts in most segments and also have severe head defects.

Mutant embryos show an increase in cell death in a striped pattern in the abdominal epidermis, in the extreme posterior of each segment. The segment borders are shallow and in some cases adjacent segments run together. There is an approximately 6-fold increase in apoptosis in en expressing cells. A slight increase in cell death occurs throughout the segment.

Deletion of parts of the epidermis bearing denticles. Muscle fibres form but overall orientation of myotubes is disturbed. Although repeated parts of the epidermis are deleted interactions of the remaining cells at their contact sites provide the positional clues for the formation of attachment sites, indicating the interaction of different parts of the cuticle is essential for the formation of apodemes.

Number of heart precursor cells is twice that of wild type, moderate cardiac hypertrophy.

The entire organization of somatic muscles of the embryo is disrupted and myotubes are scattered along the ectoderm in a disfigured configuration. The longitudinal myotubes, though fused and elongated, are scattered and do not attach at the usual sites. The myotubes may contain more than the usual number of nuclei. As visualized by staining for nau RNA, dorsal and ventral muscle precursors are apparently normally distributed, though the lateral clusters are difficult to see.

Nondefective in gonad assembly.

Mutant embryos are much smaller than wild-type and typically secrete three complete denticle belts and a variable number of partial belts. Remaining denticles are essentially wild type.

Each stripe of hh expression broadened in nkd mutant embryos.

Embryos develop only a few segmental borders in the epidermis.

nkd embryos have abnormally wide stripes of hh expression.

In 16% of nkd2 mutants, all denticle belts were removed. In the remaining embryos fragments of denticle belts persisted, mainly in odd segments. The ventral cuticle pattern is nearly wild type in fu41 nkd2 double mutants.

Does not interact with RpII140wimp maternal effect.

nkd2 embryos had normal wg and arm protein distribution during midembryonic stages but changes were seen in protein accumulation at later stages.

The ventral cuticle of nkd2 embryos is almost completely devoid of denticles. The head is defective, with abnormal spiracles, and the filzkorper material is very prominent. Irregular segment borders form during germband shortening. At the end of dorsal closure only a few segmental grooves are present. The CNS is very disorganised and the brain often protrudes dorsally rather than being covered by epidermis. The PNS is abnormal.

nkd mutant embryos have Keilin's organs, but these often have four or more sensory hairs rather than the normal three. Occasionally extra, discrete organs are seen, so that three organs appear in one segment, usually accompanied by the loss of an organ from an adjacent segment. nkd2/nkd2 and nkd2/nkd3 embryos grew in in vivo culture, producing implants containing imaginal discs and all larval tissues. The discs tended to grow as a merged sheet of material. Metamorphosed implants produced adult cuticular structures derived from the eye-antenna discs, leg and wing discs.

strong allele

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

nkd2 is an enhancer of wing phenotype of Scer\GAL4en-e16E, armUAS.cWa

NOT Enhancer of

nkd2 is a non-enhancer of phenotype of arm4

Suppressor of

nkd2/nkd[+] is a suppressor of leg joint phenotype of ds1/ds38k

nkd2/nkd[+] is a suppressor | partially of tarsal segment phenotype of ds1/ds38k

nkd2/nkd[+] is a suppressor | partially of leg phenotype of ds1/ds38k

NOT Suppressor of

nkd2 is a non-suppressor of phenotype of arm4

Additional Comments
Genetic Interactions

h1/h1 nkd2/nkd3 double mutant embryos exhibit defective denticle belts.

The excess naked cuticle phenotype seen in nkd2 embryos is enhanced by RacGAP50CAR2; the double mutant embryos have uniform naked cuticle with no denticle belts at all. The excess naked cuticle phenotype seen in nkd2 embryos is partially suppressed by wgl-17/+. The ability of wgl-17/+ to suppress the excess naked cuticle phenotype of nkd2 embryos is suppressed by RacGAP50CAR2 or RacGAP50CDH15; the triple mutant embryos secrete uniform cuticle with no denticle belts.

nkd2/+ partially suppresses the leg phenotype of ds38k/ds1 flies: tarsal joint formation is completely rescued and the size of the tarsal segments is recovered almost to that of wild type.

An ectopic NB 7-3 is formed in 76% of hemisegments in gsbIIX62 ; nkd2 embryos.

The formation of excess naked cuticle in nkd2 embryos is suppressed by the expression of shiK44A.Scer\UAS under the control of Scer\GAL4en-e16E and the head defect is partially rescued in these embryos.

Xenogenetic Interactions

Expression of nkd::Btau\recoverinrEF.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4da.G32 largely rescues the cuticle defects of nkd2/nkd3 embryos and adult viability is restored.

Expression of nkd::Hsap\NKD2hEFX2.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4da.G32 largely rescues the cuticle defects of nkd2/nkd3 embryos and adult viability is restored.

Expression of Mmus\Nkd1Scer\UAS.T:Avic\GFP-EGFP under the control of Scer\GAL4da.G32 fails to rescue the cuticle defects of nkd2/nkd3 embryos.

Expression of nkd::Mmus\Nkd1f30aa.Scer\UAS.T:Avic\GFP-EGFP under the control of Scer\GAL4da.G32 fails to rescue the cuticle defects of nkd2/nkd3 embryos.

Complementation and Rescue Data
Fails to complement
Images (0)
Stocks (3)
Notes on Origin

Expression patterns of wg, en, patch, ci and Ubx are similar to those in embryos with ectopic uniform wg expression. The en stripe broadens in the posterior direction. nkd2 embryos have same pattern of arm RNA expression as those with uniform wg expression, but different protein distribution, with a high level all over, plus 2 stripes/segment where wg is expressed.

gsb-n protein expression has been studied in nkd2 embryos.

Mutations in nkd suppress the wg phenotype. The inappropriate specification of naked cuticle requires wg activity.

Strong nkd allele.

External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (6)
References (51)