The size distribution of regenerated adult wings in fru3 heterozygous mutants that were subjected to ablation of imaginal wing disc tissue during the larval stage, is significantly shifted towards bigger wing size compared to similarly treated controls.
fru3 mutant males display active intermale courtship. When subjected to daily ethanol exposure, the courtship level of fru3 males is decreased on the first exposure and then remains unchanged on subsequent exposure. the intermale courtship level of fru3 males is significantly lower than that of CS control males on the third exposure.
The Muscle of Lawrence fails to differentiate in 90% of fru3 homozygous mutants, with the remaining 10% exhibiting only a vestigial muscle of Lawrence.
Flies transheterozygous for fruΔC and fru3 exhibit approximately 33% fertility compared to wild-type. They do not experience reduced viability. These flies also exhibit reduced courting of females while displaying higher levels of intermale courtship and chaining. The muscle of Lawrence fails to differentiate in 90% of cases, with the remaining 10% exhibiting only a vestigial muscle of Lawrence.
fruΔC/fru3 transheterozygotes exhibit a reduced number of male serotonergic neurons and improper patterning. The dorsal serotonergic abdominal giant neurons (dSAbg) exhibits approximately 18%, and the ventral serotonergic abdominal giant neurons (vSAbg) approximately 6% of the normal complement of serotonergic neurons. At least one or the other of these clusters is absent in a significant portion of these males; the vSAbg is undetectable in approximately 70%, whereas approximately 22% exhibit no dSAbg. In animals lacking the vSAbg, the remaining dSAbg neurons innervate the vas deferens, accessory glands, and ejaculatory duct. Similarly, in animals with no dSAbg, the same target organs are innervated by neurons of the vSAbg. In animals with only one cluster, while the innervation of the vas deferens is wild-type in pattern, the innervations are less dense. Similar observations are found for the accessory glands and ejaculatory duct. Unlike wild-type males, 90% of accessory glands are not fully innervated and a further 5% have no innervation. This phenotype is repeated with the vas deferens. These males experience a 8.5% decrease in fru[M]-labelled neurons compared to wild-type.
During a 6hr observation, fruΔC/fru3 males do not mate, whereas approximately 50% of fruΔC/fru3 males expressing fruMC.Scer\UAS.cSa do. These males are slower to initiate mating, although the duration of copulation is similar to that of wild-type males. A small number of control flies (i.e. fruMC.Scer\UAS.cSa/+ ; fruΔC/fru3) manage to mate within the same time as the 'rescued' males, probably due to 'leakage' of the transgene, although mating durations are still significantly longer than those of wild-type males.
fru3/fru4-40 males exhibit very little courtship behaviour towards females and show a small but significant increase in courtship of other males compared to wild-type. Unlike wild-type males, these mutant males form male mating chains.
The male-female courtship index and fertility of fruGAL4/fru3 males is significantly reduced compared to wild-type. These males court single wild-type males and form chains with males of their own genotype.
Expression of 5-HT in serotonergic-abdominal ganglion neurons in adult males is absent.
fru1/fru3 males mated individually to a single virgin female show vigorous courtship behaviour, comparable to that of wild-type males. High levels of abdominal bending are seen in the males that show courtship behaviour. However, the proportion of males that mate is reduced compared to wild type; 30% of the transheterozygous males court but do not mate. The fertility of the males (as assayed by the ability of the mated females to produce progeny) is reduced compared to wild-type males. The transheterozygous males show longer than normal mating-initiation latencies compared to heterozygous controls. Mating duration is also longer than normal and shows a far more scattered distribution than that of wild-type males.
The number of progeny (number of resulting pupae) obtained from a fertile mating between a fru1/fru3 male and a wild-type female are not slightly but significantly fewer compared with wild type.
An appreciable fraction of matings by fru1/fru3 males lead to subnormal quantities of sperm being transferred to the female.
Homozygous males show high levels of head-to-head interactions compared to wild-type males. Most of these would-be aggressive actions involve bringing their heads together but not escalating the interactions into the rising-up and boxing motions that are displayed by wild-type males. The level of head-to-head interactions shows a temporal dependency; when males are grouped together on the day they eclose they do not show significantly higher than normal head-to-head interactions, but the frequency of head-to-head interactions shows a marked increase beginning on day 2 and peaking on days 4-5. Mutant males aged individually for 5-7 days and then grouped together show low levels of head-to-head interactions 1 day after being grouped together, but show an increase in the frequency of head-to-head interactions by days 4-5. These flies (which were aged individually) show lower levels of head-to-head interactions compared to mutant males that have been aged for essentially the same number of days, but in the presence of other males since eclosion, indicating a social component in the phenotype. Mutant males show some chaining behaviour. Chaining also show temporal dependence, with the frequency of chaining showing a marked increase beginning on day 2 and peaking on days 4-5.
Males are less stimulated to court females than fru1 or fru0-1 and display less chaining behaviour than fru1 males. Some males that exhibit courtship do exhibit tapping behaviour (tapping of the female with the forelegs). No courtship song pulse is generated, even though they perform rare and unsustained wing extensions. The anomalous wing usage exhibited is not due to a general thoracic etiology, such as a defect in neuromuscular morphology or physiology. Homozygous and transheterozygous males with fru4 exhibit complete behavioural sterility, failure to attempt copulation. Males, when presented with both sexes simultaneously, will show a courtship bias toward males. Chaining behaviour exhibited by males is displayed mostly on the food surface. Courtship song is not required for, nor is particularly correlated with, chain formation. The behaviour of fru3/fru4 males is very similar to that of either homozygote. Males lack the Muscle of Lawrence (MOL). Subnormal levels of courtship are not related to any drop in activity or viability. Mutant females are courted by wild-type males at normal levels.
Males lack the muscle of Lawrence.
Males court indiscriminately, fail to copulate and have muscle of Lawrence defects. Males show very little wing extension and the wing displays generate no song pulse signals (courtship specific as flight is normal). fru3/fruw12 males barely court at all but show normal locomotor activity. Mutant combination shows some male-male chaining. Early and late steps of courtship are disrupted.
In fru3 homozygotes the number of adult muscle nuclei per fibre is greater than that for other fru- mutants but there are fewer nuclei in muscle of Lawrence (MOL)-position fibres than medial fibres or wild-type male MOL fibres. The number of myoblasts in unaffected.
Males court males and females but fail to mate. Male specific abdominal muscle is reduced.