|Feature type||allele||Associated gene||Dmel\Khc|
|Map ( GBrowse )|
|Allele class||loss of function allele, amorphic allele - genetic evidence|
What does this section display?
This section contains items that were added to this record for each release. It currently only tracks new links between this FlyBase report and other FlyBase data classes (e.g. genes, references, stocks) or controlled vocabulary terms (e.g. GO, anatomy terms).
What does this section not display?
This section does not currently display links that were removed or gene model changes.
Click the icon below to subscribe to this FlyBase record and receive updates automatically through your feed reader.
|All updates||Click here to see a list of all updates to this record from FB2010_08 and on.|
|Nature of the Allele|
|Mutations Mapped to the Genome|
|Associated Sequence Data|
|Nature of the lesion|
Nucleotide substitution: C513T.
|Phenotype Manifest In|
adult cuticle & scutellar bristle | somatic clone
eye photoreceptor cell & endoplasmic reticulum | somatic clone
eye photoreceptor cell & multivesicular body | somatic clone
follicle cell & mitochondrion | germ-line clone
germline cyst & mitochondrion | germ-line clone
microtubule & oocyte | oogenesis stage S9 | germ-line clone
stage S9 oocyte & nucleus | germ-line clone
The 50% lethal phase of Khc/Khc, Khc/Khc and Khc/Khc animals on normal and rich food is the third larval instar stage. On poor food, the 50% lethal phase is shifted to the pupal stage. Khc/Khc, Khc/Khc and Khc/Khc larvae show reduced flux of neurosecretory dense core vesicles compared to wild type and no flux of mitochondria along the axons. Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc and Khc/Khc larvae show reduced flux of neurosecretory dense core vesicles along the axons compared to wild type. Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc and Khc/Khc larvae show reduced flux of both neurosecretory dense core vesicles and mitochondria along the axons compared to wild type.
Both anterograde and retrograde flux of axonal mitochondria is inhibited in Khc/Khc, Khc/Khc, Khc/Khc, Khc/Khc and Khc/Khc larvae. 100% of eggs from females containing homozygous germline clones show defects in dorsal appendage morphology; 11% have fused dorsal appendages, 2% have reduced dorsal appendages and 87% have missing dorsal appendages. The velocity of ooplasmic streaming in stage 10B oocytes is dramatically reduced in mutant females compared to wild type.
Homozygous Khc mutant class IV dendritic arborization (da) neurons in the third instar larva display abnormal dendritic and axonal morphologies.
Cytoplasmic streaming is completely arrested in mutant egg chambers.
In stage 9 oocytes from Khc27 homozygous germline clones, the accumulation of microtubule plus ends in the posterior of the oocyte fails to occur.
Khc27 mutant clonal prefollicular cysts show premature mitochondrial accumulation at the middle of the fusome compared to wild-type cysts. The Balbiani body is abnormally large in the oocytes that develop from these clones. These defects persist in older follicles. Mitochondria cluster at the apical side of Khc27 young mutant follicle cells (from germline clones) but the mitochondrial distribution is normal in follicles older than stage 7. In Khc27 mutant germline stem cells, all the mitochondria are clumped at the opposite side from the spectrosome, instead of being clustered around the spectrosome as in wild-type stem cells. While mitochondria in dividing cysts are normally spread evenly throughout the cytoplasm, in cysts from Khc27 germline clones, the mitochondria clump away from the fusome.
In Khc17/Khc27 larval motor axons, the anterograde and retrograde flux of mitochondria is reduced by 70-90%. The number of mitochondria in these mutant nerves is reduced by 50.5% in segments A2-A3. The reduction in mitochondrial anterograde and retrograde flux is also seen in Khc6/Khc27 larval motor axons. Khc27/+ larval nerves contain abundant mitochondria but show a small shift in the mitochondrial anterograde duty cycle from forward runs to pauses and a 16% decrease in anterograde run duration. However, mitochondria in these nerves show an increase in retrograde flux.
Khc27 mutants are embryonic lethal. In stage 8-9 Khc27 oocytes, no slow streaming currents are observed, but endosomes do show short-range saltation. The mean velocity for anterior endosomes is approximately 2.8-fold less than in wild-type. In stage 10B-11 Khc27 oocytes, no fast streaming currents are observed. Rather, endosomes undergo short-range saltation and little net displacement, moving approximately 32-fold slower than in wild-type. Yolk endosomes are concentrated towards the posterior, leaving a clear zone at the anterior.
When homozygous germ-line clones are made the resulting eggs show defects in their dorsal appendages. Only 1% have normal appendages. Of the remainder 17% have fused appendages. 26% have a rudimentary dorsal bump, and 56% showed no dorsal material. Nuclear positioning is defective in about half of stage 9 and 10 null oocytes. Nuclei appear to accomplish the initial posterior to anterior shift during stage 7. Although some nuclei are mispositioned in stage -8 mutants, there is a marked shift away from the anterior margin in stages 9 and 10.
Khc27 germ-line clone oocytes have normal microtubule organization, but markers of the pole plasm are relocated from the posterior pole to other parts of the oocyte cortex. The stage 8 oocytes of Khc27 heterozygotes show partial mislocalisation of pole plasm markers away from the posterior pole, but this defect is largely corrected by stage 9.
Females in which Khc27 germ-line clones have been induced lay eggs with dorsal appendage defects, ranging from fusion (37%) to posterior displacement and reduction (43%), to complete loss (28%). All of these eggs form an aeropyle at the posterior. The oocyte nucleus is mis-placed in 62% of stage 9-10 Khc27 germ-line clone oocytes.
Khc27 germ line clone oocytes have mis-positioned nuclei: the nucleus migrates correctly to the anterior during stage 8, but in about 50% of stage 9 oocytes it does not maintain its anterior position. After anterior detachment, the nucleus maintains a tight association with the lateral cortex.
The movement of stauαTub67C.T:Avic\GFP-m6-expressing particles in the nurse cell cytoplasm is indistinguishable from that of wild type in egg chambers derived from homozygous female germline clones, but in the ooplasm most of the particles are static (in contrast to wild type) except for those in the vicinity of the ring canals. The ooplasmic streaming seen in stage 9 and 10b wild-type oocytes is completely abolished in oocytes derived from homozygous female germline clones. The yolk vesicles fail to move in mutant oocytes, although the uptake of the yolk from the follicle cells is unaffected and the oocyte grows at the normal rate.
Homozygous clones of substantial size can be produced in the eye when the clones are induced 1-2 days after egg laying. Homozygous clones in the wing disc appear to proliferate normally. The mechanosensory bristles in homozygous wing clones are sometimes kinked. Homozygous clones in the eye produce a slightly roughened eye surface. Approximately 20% of the ommatidia within these clones are missing one or two photoreceptors. Some photoreceptors show structural defects, including disordered packing of microvilli and split or buckled rhabdomeres. The number of photoreceptors with such abnormal rhabdomeres varies from clone to clone but never exceeds 5-10%. Defects appear equally severe in small or large clones. No dramatic differences in the organisation of the rough ER or Golgi membranes is seen in homozygous (those with or without contorted rhabdomeres) or neighbouring wild-type photoreceptors. Occasionally, homozygous photoreceptors show a slight increase in the abundance of ER near the Golgi and slightly increased levels of vesicles and multivesicular bodies. No defects in the positioning of mitochondria or nuclei are seen. The defects seen appear to be cell autonomous. Degenerating photoreceptors are seen at a low frequency in flies aged for more than two weeks after eclosion. Bristles in clones in the adult epidermis may lie flat or twisted along the epidermal sheet rather than projecting outward from its surface. The deflection of individual bristles with a tungsten needle usually causes a bend or kink rather than the pivoting needed to elicit the wild-type grooming reflex. The scutellar macrochaetae are usually approximately 20% shorter than normal. This length defect is less evident in shorter macrochaetae and is not seen in microchaetae. The tips of bristles are often contorted and the contortions are most severe at the tips of long macrochaetae, which always have flattened, flared or twisted tips. Microchaetae show bluntness or a slight tip swelling. No defects are seen in the remainder of the integument, including the bristle sockets, the nonsensory hairs of the epidermal cells or the epidermal cuticle sheet. The severity of the defects are not detectably affected by clone size. The cuticle layers of homozygous scutellar bristles are quite thin. This effect is more pronounced at the tips of the bristles than at their bases.
Homozygous Khc27 germ-line clones produces embryos that usually arrest before blastoderm formation, with the occasional embryo surviving until early gastrulation stages.
Hemizygotes show at least 50% lethality during the second larval instar stage.
|Phenotype Manifest In|
Khc/+ ; ens[ΔC]/+ double heterozygous females show some stratification of late oocytes, suggesting a defect in cytoplasmic streaming.
Aplip1EK4/+; Khc27/+ larvae show posterior paralysis in 86% of cases; these mutants also show axonal swelling. Expression of the Aplip1+tHa transgene fully rescues the posterior paralysis phenotype of Aplip1EK4/+; Khc27/+ larvae and partially rescues the axonal swelling phenotype.
|Complementation & Rescue Data|
|Fails to complement|
|Stocks ( 0 )|
|Notes on Origin|
|External Crossreferences & Linkouts|
|Synonyms & Secondary IDs ( 2 )|
|Secondary FlyBase IDs|
|References ( 32 )|
|Generate a list of|
|List References by type|
|Recent research papers ( 4 )|