Third instar larvae expressing Rac1N17.UAS under the control of Scer\GAL4elav-C155 display supernumerary mature and satellite NMJ boutons. A significant increase in the number of synaptic boutons containing microtubule loops points towards an increase in microtubule stability.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4GMR13F02 (in combination with a Gal80[ts] transgene to restrict expression to the adult stage) results in enhanced memory after conditioning in an olfactory conditioning assay.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4slbo.2.6 alters border cell cluster migration, with changes in local protrusion and retraction behaviour.
The follicle cells of degenerating egg chambers from flies expressing Rac1N17.Scer\UAS under the control of Scer\GAL4GR1 show defects in the normal engulfment of dying germline cells. Unlike in wild type, the follicle cells fail to enlarge as nurse cell chromatin condenses and minimal uptake of nuclear fragments is seen. As egg chamber death progresses, the follicle cells die at the later stages. This phenotype is seen in both the presence and absence of starvation, however the follicle cells from starved flies usually do not die until later phases.
Class III ddaA neurons expressing Rac1N17.Scer\UAS under the control of Scer\GAL41003.3 show a significant decrease in the number of dendritic sensory filopodia compared to wild type. The average length of the filopodia is significantly decreased compared to wild type, while the total length of primary dendritic branches is not altered.
Larvae expressing Rac1N17.Scer\UAS under the control of Scer\GAL41003.3 show a reduced response to gentle touch compared to controls.
Flies with induced expression of Rac1N17.Scer\UAS for three days under the control of Scer\GAL4elav-C155 and Scer\GAL80ts.αTub84B show a remarkable tolerance to paraquat-induced oxidative stress, desiccation, starvation and high temperature. These flies survive for 50-100% longer than control flies in adverse conditions.
The body weight of flies expressing of Rac1N17.Scer\UAS for three days under the control of Scer\GAL4elav-C155 and Scer\GAL80ts.αTub84B is largely comparable to un-induced controls, although a marginal but statistically significant increase is found in males. The level of triglyceride, the primary storage form of lipid, is not altered either. The fecundity of female flies as determined by the number of eggs laid per fly per day is not compromised compared to that of controls.
Continuous expression of Rac1N17.Scer\UAS under the control of Scer\GAL4elav-C155 and Scer\GAL80ts.αTub84B (with flies kept at 30[o]C) does not confer any obvious beneficial or detrimental effects on life span.
Flies with induced expression of Rac1N17.Scer\UAS for three days under the control of Scer\GAL4Cha.7.4 and Scer\GAL80ts.αTub84B exhibit improved survival rates compared to controls when exposed to 20 mM paraquat and desiccation.
Flies with induced expression of Rac1N17.Scer\UAS for three days under the control of Scer\GAL4repo and Scer\GAL80ts.αTub84B do not exhibit improved survival rates compared to controls when exposed to 20 mM paraquat and desiccation.
Hindgut epithelial cells do not show the left-right asymmetry in cell shape which is seen in wild-type hindgut epithelial cells at late stage 12 (before epithelial tube rotation) in embryos expressing Rac1N17.Scer\UAS under the control of Scer\GAL4NP2432.
Adult flies conditionally expressing Rac1N17.Scer\UAS under the control of Scer\GAL4elav.PU (using tub-Gal80[ts] to limit the expression to the adult stage) display significantly slower memory decay at later time-points but perform comparably to wild-type at early time-points shortly after the training stage in an aversive olfactory assay. The immediate (3 min) memory performance is unaffected regardless of the training intensity (electric shock intensity or number of pulses); the prolonged memory effect lasted less than four days, memory retention of adult flies on day 4 after 10 spaced training sessions is not significantly higher compared to controls. However, sensimotor responses of Rac1N17.Scer\UAS expressing flies to electric shock or odors used in the conditioning are comparable to controls.
Cold shock amnesia treatment applied 2 hr after training completely abolished the enhanced 3hr and 24hr memory performance of adult flies expressing Rac1N17.Scer\UAS under the control of Scer\GAL4elav.PU (using tub-Gal80[ts] to limit the expression to the adult stage) while treatment with cycloheximide had no effect on their long-term memory performance.
Adult flies conditionally expressing Rac1N17.Scer\UAS under the control of either Scer\GAL4ey-OK107 or Scer\GAL4238Y (using tub-Gal80[ts] to limit the expression to the adult stage) display enhanced 3 hr memory in an aversive olfactory assay compared to controls, this memory enhancement is not observed when any of the following drivers are used: Scer\GAL4Orco.PU, Scer\GAL4OK66, Scer\GAL4GH146, Scer\GAL4Feb170 or Scer\GAL4Alp4-c232. The memory enhancement is also not observed when Rac1N17.Scer\UAS is driven by Scer\GAL4ey-OK107 in the presence of Scer\GAL80Mef2.mb247 (expressed in the mushroom body). Of several subtype-specific mushroom body drivers tested, only expression under the Scer\GAL4D52H driver leads to 3hr memory enhancement, expression controlled by the others (Scer\GAL417d, Scer\GAL4c739, Scer\GAL4c305a, Scer\GAL41471, Scer\GAL4NP1131, Scer\GAL4Tab2-201Y, Scer\GAL4NP0065 and Scer\GAL4c320) had no effect.
Retroactive interference (training flies to acquire a novel odor-shock association) introduced at 1.5 hr after the initial learning has no effect on memory retention of the initial odor-shock association (but the acquisition of new learning is not impaired) in flies expressing Rac1N17.Scer\UAS under the control of Scer\GAL4elav.PU (using tub-Gal80[ts] to limit the expression to the adult stage), while in wild-type it leads to interference induced forgetting . The Rac1N17.Scer\UAS expressing adults perform significantly worse compared to wild-type in a reversal learning aversive olfactory assays (in which the odor-shock contingency is reversed in each training session and wild-type flies tend to avoid the odor paired with punishment most recently). This suggests that Rac1N17.Scer\UAS expressing flies have impeded forgetting and thus are less able to remove inappropriate old memories during reversal learning.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4DB331 does not alter the overall dendritic architecture in the lobular plate tangential cells; neither the position not branching patterns of primary and secondary order dendrites are affected. However, there is an increase in spine density and a change in spine morphology (the spines appear shorter and less well defined) compared to controls.
The salivary gland fails to migrate posteriorly and some cells remain at the ventral surface in embryos expressing Rac1N17.Scer\UAS under the control of Scer\GAL4fkh.PH.
Expression of Rac1N17.Scer\UAS under the control of cer\GAL4ato.3.6 results in a marked increase in the number of axons from dorsal cluster neurons crossing the optic chiasm (an average of only 19.8 axons crossing in contrast to the wild-type average of 11.7).
Expression of Rac1N17.Scer\UAS in myoblasts, driven by Scer\GAL41151, affects indirect flight muscles. There is a reduction in the mean number of dorsal longitudinal muscle (DLM) fibers (from 6 to ~4) and in DLM size (35% reduction in area). Additionally, the tergal depressor of trochanter (TDT) and the dorso-ventral muscles (DVMs) are almost completely absent. Expression of Rac1N17.Scer\UAS, under the control of Scer\GAL41151, does not affect the number of adult muscle precursors present at late embryonic stages. However, there is an approximately 43% reduction in the number of myoblast numbers in the wing discs of third instar larva. Experiments using Scer\GAL80ts.αTub84B show that Rac1N17.Scer\UAS needs to be expressed during larval stages to affect muscle development. Expression of Rac1N17.Scer\UAS, under the control of Scer\GAL41151, affects pupal myogenesis. DLM myoblast expansion and proliferation follows a different pattern in Scer\GAL41151/+; Rac1N17.Scer\UAS/+ mutants compared to controls: in the mutants there is no significant increase of proliferation at 12-16 hours APF and there is a sharp decline in expanse by 20 hours APF. At 16 hours APF, Scer\GAL41151/+; Rac1N17.Scer\UAS/+ myoblasts undergo less fusion than controls. Fiber formation is delayed compared to controls, and by 24 hours APF, the majority of Scer\GAL41151/+; Rac1N17.Scer\UAS/+ mutants have only 3 DLM fibers, instead of the wild-type number of 6. Pupal myogenesis is severely affected in the DVMs of Scer\GAL41151/+; Rac1N17.Scer\UAS/+ mutants. Myoblast proliferation fails to increase at 12-16 hours APF and there is a sharp decline at 20 hours APF. At 16 hours APF, Scer\GAL41151/+; Rac1N17.Scer\UAS/+ DVM myoblasts are disorganized and are not aligned along the long axis of the founder cells, as occurs in wild type. At 20-24 hours APF, control myoblasts become compact and rounded, while Scer\GAL41151/+; Rac1N17.Scer\UAS/+ DVM myoblasts fail to assume this shape. Myoblast segregation and fusion does not occur in the mutants. By 20 hours APF, when DVM fiber formation is complete in controls, myoblasts of Scer\GAL41151/+; Rac1N17.Scer\UAS/+ mutants remain unpatterned.
When Rac1N17.Scer\UAS is driven by Scer\GAL4elav.PLu, embryos display mild midline axon outgrowth defects, with small breaks in the outermost longitudinal pathways, with rare axons ectopically crossing the midline.
Expression of Rac1N17.Scer\UAS in border cells, driven by Scer\GAL4slbo.2.6, inhibits the migration of border cell clusters to the oocyte. However, the apical cap of these egg chambers forms and is shed normally.
Expression of Rac1N17.Scer\UAS, under the control of the hemocyte-specific driver Scer\GAL4crq.PO, inhibits hemocyte migration in the embryo by stage 14. Hemocytes begin migration out of the head region, but then lose polarized migration and accumulate in the anterior of the embryo. At stage 17, the ventral nerve cord is shorter in Rac1N17.Scer\UAS embryos than in wild-type, indicating that the VNC fails to condense correctly in Rac1N17.Scer\UAS mutants. Expression of Rac1N17.Scer\UAS in the lateral glia, driven by Scer\GAL4158, results in inhibition of VNC condensation in embryos but does not affect the differentiation or survival of the lateral glial cells. Expression of Rac1N17.Scer\UAS throughout the CNS, driven by Scer\GAL4elav-C155, does not affect the condensation of the VNC in embryos.
Expression of Rac1N17.Scer\UAS in the aCC/RP2 axons (under the control of Scer\GAL4eve.RN2), results in stalling in 15.2% of hemisegments. Stalled aCC/RP2 axons cause a co-arrest of the complete intersegmental motor nerve in 90% of cases.
Developmental dispersal of hemocytes is abnormal in embryos expressing Rac1N17.Scer\UAS under the simultaneous control of both Scer\GAL4Pxn.PS and Scer\GAL4crq.PA.
One hour after laser-induced wounding, approximately half the number of hemocytes are recruited to the wound in embryos expressing Rac1N17.Scer\UAS under the simultaneous control of both Scer\GAL4Pxn.PS and Scer\GAL4crq.PA compared to wild type embryos. Hemocytes that are recruited in the mutant embryos have significantly reduced lamellar protrusions.
Expression of Rac1N17.Scer\UAS in segmental stripes of the embryonic epithelium, driven by Scer\GAL4en-e16E, inhibits the production of actin protrusions and the actin cable within epithelial cells. These embryos are able to complete dorsal closure but the Rac1N17.Scer\UAS-expressing cells fail to fuse properly, which results in the presence of small holes in the midline. These embryos also show segmental mismatching along the midline.
Rac1N17.Scer\UAS; Scer\GAL41151 pupae have severely reduced myoblast fusion, the effect being most dramatic in the lateral muscles of the abdomen and, to a lesser extent, in the thoracic muscles. The lateral muscles of the abdomen in these pupae don't fuse and the resulting unfused myoblasts cluster around founder myoblasts, but do not differentiate further. Each unfused founder cell elongates and differentiates into a thin myotube eventually eventually developing into a mononucleate fibre. By contrast, some fusion does occur in the developing dorso-ventral indirect flight muscles. The putative founders myoblasts of these muscles are present in the pupal thorax in a wild-type pattern. These founders initiate fibre formation, but to a lesser extent than normal, leading to the formation of fibres with fewer nuclei than wild-type fibres of the same stage. The resulting muscles are abnormally thin, but form at the correct position and with the correct number of fibres.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4gcm-rA87.P blocks macrophage migration in embryos; only a few macrophages move anteriorly and posteriorly for short distances.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4Cg25C-A109.1F2.P causes macrophages to clump in various areas of the embryo (such as the head region, around the pharynx, midgut and hindgut and laterally along the ventral cord). This defect is seen at stage 16, but becomes more pronounced during stage 17. The macrophages are abnormal in shape in the mutant embryos, appearing rounder than normal due to a block in the formation of cellular protrusions.
Macrophages expressing Rac1N17.Scer\UAS under the control of Scer\GAL4unspecified show wild-type levels of cortical F-actin. The macrophages have few or no cytoplasmic extensions in the mutant embryos.
Flies expressing Rac1N17.Scer\UAS under the control of Scer\GAL4GMR.PU have rough eyes with a loss of rhabdomeres, abnormal photoreceptor cells, vacuolated material in the retina and polarity defects.
When expression is driven by Scer\GAL4He.PZ, hemocyte proliferation is unaffected, lamellocytes are abnormal and replaced by multinucleate cells that do not express lamellocyte markers and crystal cells are decreased.
Rac1N17.Scer\UAS; Scer\GAL4btl.PS embryos have tracheal defects including truncated and/or zig-zagged dorsal trunk, misguided dorsal branches and a lack of terminal branches. The cell rearrangements occurring during extension of the dorsal branches towards the dorsal midline are greatly inhibited in these embryos: migration of cells to form the dorsal branch begins, but the number of cells contributed is less than in wild-type, and the resulting dorsal branches are shorter, occasionally failing to form at all.
Although Rac1N17.Scer\UAS; Scer\GAL4elav.PLu embryos have occasional defects in the segmental nerve (SN)b and SNa motoneurons, they always extend their axons out of the CNS (as part of the abdominal posterior fascicle). In some cases (16%), the lateral branch of SNa motor axon actually extends beyond its target muscles.
When Rac1N17.Scer\UAS is driven by Scer\GAL4repo, mutant embryos have mildly disrupted glial wrapping profiles with occasional small gaps in the nerve sheath. Sensory neurons also show defasciculation.
Expression of Rac1N17.Scer\UAS, driven by Scer\GAL4332.3, causes a failure to secrete cuticle in 61% of embryos and holes in the dorsal surface of 8% of embryos that do manage cuticle secretion. Expression of Rac1N17.Scer\UAS, driven by Scer\GAL4332.3, results in impairment of amnioserosa morphogenesis and migration of the epidermis. The amnioserosa of these mutants remains elliptical at an age where the same tissue is narrowing in wild type. This lack of morphological change appears to impede the movement of the epidermis resulting in a dorsal hole which is larger than in wild type. Within a single mutant embryo there may be patches of cells that change shape correctly and patches that do not. The progression of the epidermis is impeded more around patches of cells that have failed to change shape. Overexpression of Rac1N17.Scer\UAS driven by Scer\GAL4c381 does not cause failure of cuticle formation. However, embryos do fail to complete dorsal closure and have a large dorsal hole in the cuticle extending from the middle of the dorsal surface to the rear of the embryo. Additionally, the epidermis fails to migrate over the amnioserosa.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4btl.PS does not affect lumen formation in the tracheal system although these embryos do show some defects in tracheal branch migration.
77.6% of ommatidia in mutant somatic clones (driven by Scer\GAL4hs.2sev) in the eye are normal. 18.1% have rotated ommatidia, 0.5% have chirality defects, 0.7% are achiral (3.1% unscorable).
When Rac1N17.Scer\UAS is driven by Scer\GAL4elav.PLu dramatic effects are seen on axon guidance. The intersegmental nerve b (ISNb) fails to branch off and enter the ventral muscles and instead follows the ISN distally toward dorsal muscles. The SNa motor axons also sometimes abnormally project to lateral muscle targets, bypassing their normal targets.
Approximately 70% of axons expressing Rac1N17.Scer\UAS under the control of Scer\GAL4A307 exhibit morphological abnormalities such as excess branching in the target region. The axons often send ectopic projections across the midline into the contralateral side of the ganglion in T2 or extra processes down into T3, a phenotype never seen in controls. In some cases one GF splits and makes bilateral bends while its partner grows on into T3 without making any bend. Often the axons split several times sending a number of projections to inappropriate parts of the ganglion. In addition to these extra processes the lateral bends, along which the synapse with the TTMn can be formed, are always seen in T2.
The function of the GF-TTMn synapse in Scer\GAL4A307; Rac1N17.Scer\UAS flies in both the response latency and the percentage following at 250Hz are normal.
Dendritic defects are seen in about 25% of Scer\GAL4A307; Rac1N17.Scer\UAS GFs. The dendritic field always contains its distinct domains, but the large dendrites have a brush-like appearance with many small processes emanating from the larger ones.
Approximately 81% of Scer\GAL4A307; Rac1Scer\UAS.cLa flies exhibit a bendless GF phenotype, while 64% of Scer\GAL4A307; Rac1Scer\UAS.cLa GFs are bendless. The remainder exhibit wild-type bends or large abnormally shaped processes in the target region.
When expression is driven by Scer\GAL4elav-C155, ISNb shows a bypass phenotype. The CNS shows similar breaks in longitudinal connectives to those of trio loss of function mutants.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL4unspecified during rhabdomere morphogenesis results in reduced, disorganised rhabdomeres. Fewer microvilli than normal are seen in cross section and a well-defined rhabdomere base is not formed; apposed sheets of membrane are involuted into the photoreceptor cytoplasm. The actin cytoskeleton appears diffuse and disordered.
Rac1N17.Scer\UAS when driven by Scer\GAL4hs.2sev leads to planar polarity, defects in the eye. This phenotype is enhanced by the addition of Df(3L)Ar14-8, which removes the Rac1 gene. Although it is mostly ommatidial rotation that is randomised in Scer\GAL4hs.2sev, Rac1N17.Scer\UAS mutants the enhancement of the phenotype by Df(3L)Ar14-8 increases the number of symmetrical, achiral ommatidia. These phenotypes appear early in development, suggesting they are primary defects.
Expression of Rac1N17.Scer\UAS under the control of Scer\GAL448Y in the developing midgut causes a delay in migration of the endodermal midgut cells.
Scer\GAL4elav-C155-mediated expression causes ISNb axons to extend past the ventral longitudinal muscles. ISNb axons may also form a distinct fascicle that follows the ISN beyond ventral muscles. Phenotype of segments showing any evidence of ISNb bypass or the full bypass phenotype is more severe with Scer\GAL41407 or Scer\GAL4elav.PLu-mediated expression. Scer\GAL4elav-C155-mediated expression causes the dorsal projection of SNa axons to extend beyond the distal edge of muscle 4 or the axons extend beyond the target site to make ectopic contacts onto dorsal muscles, sensory sheath cells or ISN axons. Phenotype is more severe with Scer\GAL41407 or Scer\GAL4elav.PLu-mediated expression. Scer\GAL4elav-C155-mediated expression causes defects in the morphology of the CNS pathways. Coexpression of Rac1Scer\UAS.cLa under the same Scer\GAL4 driver yields near normal morphology of the CNS pathways, some abnormalities can be seen in occasional segments.
Embryos exhibit a dorsal open phenotype.
Causes duplications and triplications of wing hairs when expressed using Scer\GAL4ptc-559.1. The duplicated or triplicated hairs are morphologically indistinguishable from wild-type. Actin distribution in Rac1N17.Scer\UAS expressing cells is abnormal at 30-35 hours after puparium formation, and microtubules appear disorganised 30-32 hours after puparium formation.
Scer\GAL4198Y- or Scer\GAL4306-mediated expression causes no or little border cell migration in 80% stage 10 egg chambers. 19 to 22% of laid eggs hatch. Scer\GAL4458-mediated expression causes arrested migration in 10% of stage 10 egg chambers. Removing Rac1 activity during migration (using Scer\GAL4hs.PB) seems to halt all activity.
Wing discs expressing Rac1N17.Scer\UAS using Scer\GAL4ptc-559.1 often contain dead cells that are extruded from the basal side of the epithelium. Adherens junction actin is disrupted in cells expressing Rac1N17.Scer\UAS. Wings derived from discs in which Rac1N17.Scer\UAS is expressed using Scer\GAL4ptc-559.1 are of normal length but narrow, with the reduction in wing area restricted to the anterior compartment. Wing hairs are often duplicated or triplicated, the penetrance of this phenotype decreasing at the wing margin.