The neuromuscular junctions of homozygous gig109 mutant larvae (muscle 4 of segment A2-4) show a significant increase in synaptic growth compared to controls. Boutons are larger than in controls.
The neuromuscular junctions of gig109/Df(3L)BSC830 mutant larvae (muscle 4 of segment A2-4) show a significant increase in synaptic growth compared to controls. Boutons are larger than in controls.
The amplitude and frequency of the mini excitatory junction potentials (mEJPs) recorded from muscle 6 of gig109 mutant third instar larval neuromuscular junctions are similar to wild type. Quantal content (EJP/mEJP) is also similar to wild type, indicating that there is no difference in the number of vesicles released.
The average size of adult wing cells in homozygous clones is 25.1% larger than surrounding wild-type cells. All intervein sectors with a mutant clone are larger in area than normal; the average increase in area compared to controls is 2.8%, although the increase can reach 7% if the clone occupies more than 50% of the mosaic sector. The increase in area is almost exclusively due to an increase in cell size, and in fact, the average cell number for a sector carrying a mutant clone is 11.1% less than control sectors. Mutant cells show reduced viability compared to control clones. In addition to the reduction in the number of cells seen in intervein sectors containing a mutant clone compared to controls (autonomous effect), there is also a reduction in the number of cells of non-mutant sectors of the same wing compared to controls (non-autonomous effect). The reduction is greater the larger the mutant clone is. Macro- and microchaetae in mutant clones in the notum are further apart than in wild-type homologous regions; in the acrostical region the density of microchaetae is reduced by 21.1% compared to wild type. The mutant chaetae are separated by less (but larger) cells in the mutant territory (3.85 cells in mutant tissue compared to 5.34 in wild type). Heminota containing large clones are larger than non-mutant contralateral controls (although they contain less cells than normal) and they contain more chaetae than in the control heminota.
In homozygous mutant clones that cover the whole antenna, the mutant antenna is approximately twice the size of its wild-type counterpart. Despite this the number of sensillae in the mutant antenna is about the same as seen in wild-type. The distribution of different types of sensillae of the funiculus is also unaltered. Each sensillum is enlarged in the mutant clone in approximately the same proportions as the wild-type antenna. the antennal nerve and antennal lobe of the brain is also bigger in these clones. In these mosaics, no differences are seen between the glomerular projection patterns and sibling controls. The only noticeable change is an increase in volume in the three glomeruli ipsilateral to the mutant antenna with respect to the contralateral homologs. The antennal glomerulus V shows an increase in volume of 42% and exhibits two to three-fold more synapses than the contralateral homolog. Mutant olfactory neurons exhibit normal sensory transduction. In Olfactory behavioural response tests using Ethyl Acetate (EA), mutant flies are sensitive to lower concentrations of EA, and elicit a more intense response to EA.
Cells in mutant clones in the eye and wing are larger than wild type siblings.
The axon of the neuron of homozygous anterior scutellar bristles (ASCs) is two to three times thicker than wild-type in mosaic flies, generates more collaterals and boutons, and projects into areas that the wild-type neuron never reaches. The distinction between the major and minor branches seen in wild-type flies is maintained in the homozygous neurons. The terminal bend in the metathoracic neuromere characteristic of wild-type ASC neurons is often either present in the fused abdominal ganglion or is duplicated in both the normal location and in the fused abdominal ganglion in homozygous ASC neurons. The neurons of homozygous anterior and posterior notopleural bristles often show an extended projection along the anterior branch towards the brain. Sometimes the extension is along the posterior branch, in which case the anterior branch has a normal length. The neuron of homozygous humeral bristles has an extended projection in the same direction as in wild-type, that reaches the very posterior region of the mesothoracic neuromere. The neuron of homozygous vertical bristles of the head branches at the brain mechanosensory center (its normal target) and continues towards the thorax. Homozygous mechanosensory neurons of the antenna sometimes project towards the thoracic ganglion, and show extended and more profuse branching compared to wild-type. Mosaic adults often show defects in the grooming reflex when a mutant bristle is touched.
Eye clones are identified by enlarged facets (enlarged receptor, pigment and cone cells) that usually lack interommatidial bristles. Cellular architecture within these cells is partially disorganised. Rhabdomeres sometimes lack the normal separation between individual rhabdomeres to produce a large interrhabdomeric space. The photoreceptors have synaptic terminals with more synaptic sites than those of gig+ photoreceptors.
Homozygous cells are 2-3 times normal size.