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.
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.