The neuromuscular junctions of sax4/sax5 homozygous transheterozygous third instar larvae present significantly less boutons than controls.
sax4/sax5 third instar larval C4da neurons do not show any obvious defects in the dendritic arborization, as compared to controls.
sax4/+ adults do not have any obvious wing phenotypes.
Large posterior clones of sax4 show no wing patterning abnormalities.
Less than 5% of sax4/Df(2R)H23 hemizygous mutant larvae exhibit developmental delay, lethargy, a reduction in the size of imaginal discs, brain | larval stage, and midgut structures, as well as trachea | larval stagel truncations.
When the anterior border of a sax4 clone falls between L2 and L3 in the wing, an ectopic L2 may form at the anterior boundary of the clone. sax4 clones near but anterior to L2 result in the formation of an ectopic wing vein adjacent to their anterior border. These clones often exhibit non-autonomous effects such as ectopic veins forming in wild-type tissue outside the boundaries of the clone.
Heterozygotes show a direct effect on the shape of the wing.
When neutral marked clones are induced in the ovary, the proportion of germaria carrying marked somatic stem cells 3 weeks after clone induction is around 70% of that seen one week after clone induction. For sax4 homozygous clones, the equivalent figure is around 60%.
Clones of male sax4 homozygous germline stem cells are still present in 32% of testes one week after clone induction and 6.3% two weeks after clone induction. This is in contrast to wild-type control clones, which are present in 82% of testes one week after clone induction and 64% two weeks after clone induction.
sax4/Df(2R)sax-H9 larvae show a reduction in size of the neuromuscular junction (NMJ) compared to wild type; the number of synaptic boutons/muscle surface area at muscle 6/7 is 44.1 +/- 1.0% of wild type. The evoked excitatory junctional potential (EJP) (measured at muscle 6 of segment A3) shows a decrease in amplitude in sax4/sax5 animals compared to wild type. Quantal content is reduced compared to wild type.
Mutant stage 13-14 embryos contain the normal number of crystal cells per embryo.
sax4/Df(2R)cn7969 larvae show a significant decrease in bouton number at the neuromuscular junction.
Mutant embryos lacking both maternal and zygotic sax function have a reduced number of amnioserosa cells.
Homozygous clones that occupy the entire posterior compartment of the wing have no effect on venation. Homozygous clones that occupy the entire anterior compartment of the wing have no effect on venation, but the wing is reduced in size. Homozygous wing clones where the clone boundary subdivides a compartment result in an ectopic wing vein at the clone boundary.
Clones induced in the developing eye that span the morphogenetic furrow have condensed chromosomes indicative of early stages in mitosis at the interface between the CycB-expressing and non-expressing cells. Clones at the anterior edge of the furrow show mislocalized nuclei, they fail to reach the apical surface where mitosis normally takes place. Nuclei are also misplaced when the clone is within the furrow and posterior to it. Cell fate specification is not, however, affected.
A large anterior clone in the wing (induced early in larval development) reduces the size of the wing, blunts the wing tip and causes ectopic venation. At the anterior clone boundary cells shift to a more anterior cell fate. At the anterior edge of clones that intersect the margin several margin cells posterior to wing vein L3 produce double row bristles (and not the posterior row of hairs), at other points of the wing margin double row cells fates are transformed to triple row. At the anterior edge of clones adjacent to the naked stretch of margin, ectopic distal costa are produced in the naked region. A large posterior clone in the wing (induced early in larval development) variably disrupts wing venation. Dorsal or ventral clones located anterior to wing vein L2 or dorsal clones posterior to wing vein L5 do not cause ectopic venation. Clones posterior to L2 or anterior of L5 do allow ectopic venation. Where the clone diverges from the line of the normal vein the ectopic vein is produced as a ridge on the dorsal surface.
In germline clones, only 10-25% of normal number of eggs is produced, over a much briefer time period than for wild type. Most are normal though 20% show aberrant dorsal appendages and short length.