fru¹/fru^4-40 D. melanogaster males court conspecific D. melanogaster males. They also court D. simulans and D. yakuba males, but do not court D. virilis males.

fru¹ mutant males display active intermale courtship. When subjected to daily ethanol exposure, the courtship level of fru¹ males is decreased on the first exposure and then remains unchanged on subsequent exposure.

fru¹/Df(3R)fru^w24 embryos have normal Fas2-positive and BP102-positive axon tracts in the central nervous system.

32% of fru¹/fru^sat15 males are fertile (this may reflect genetic background effects). fru¹/fru^w9, fru¹/fru^w12, fru¹/Df(3R)fru^w24, fru¹/fru^w27 and fru¹/fru^4-40 males show significantly more male-male courtship and less frequent male-female courtship than wild-type males. fru¹/fru^w9, fru¹/fru^w12, fru¹/Df(3R)fru^w24, fru¹/fru^w27 or fru¹/fru^4-40 males show substantial chaining. fru¹/fru^w9, fru¹/fru^w12, fru¹/Df(3R)fru^w24, fru¹/fru^w27 or fru¹/fru^4-40 males have a courtship song with longer interpulse intervals, but essentially normal intrapulse frequencies, cycles per pulse and width of the fast-Fourier transform compared to control males. Abdominal muscle innervation appears normal in homozygous adults. The number and pattern of divisions of larval neuroblasts in the thoracic ganglia or brain appears normal in homozygous animals.

Expression of 5-HT in serotonergic-abdominal ganglion neurons in adult males is defective; relatively few neurons express 5-HT compared to wild type.

fru¹/fru³, fru¹/fru⁴, fru¹/fru^sat and fru¹/fru^sat15 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%, 47%, 38% and 18% respectively of 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.

fru^0-1/fru¹ males show longer than normal mating-initiation latencies compared to heterozygous controls when mated to a single virgin wild-type female. The mating duration is not significantly different from wild type.

The number of progeny (number of resulting pupae) obtained from a fertile mating between a fru¹/fru⁴, fru¹/fru^sat or fru¹/fru^sat15 male and a wild-type female are not significantly different to wild type.

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 and fru¹/fru⁴ males lead to subnormal quantities of sperm being transferred to the female.

Variable amounts of seminal fluid (as assayed by transfer of Acp26Aa protein), ranging from slightly subnormal, substantially subnormal to absent, are transferred to the uterus of females mated to fru¹/fru³ males.

The varicosities of the sAbg neurons which are associated with the accessory gland are much sparser in fru¹ males than in wild type.

fru¹/fru^sat males are weakly fertile, at a rate similar to that for fru¹/fru³ or fru¹/fru⁴.

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 behaviour starts with a male approaching and tapping or slashing at the other male's head with his foreleg (occasionally, two males with approach each other simultaneously in this manner). After a given approach, the males place their heads close together. While locked in this head-to-head position, either their forelegs continue slashing movements or one male seems to hold the other's forelegs. One of the two males is often pushed backwards. 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. Two mutant males show a significantly higher level of head-to-head interaction compared to mutant male/wild-type female pairs in trio tests. In pair tests, two mutant males show a significantly higher level of head-to-head interaction compared to mutant male/wild-type male pairs or two wild-type males (although the low value seen in pairs involving wild-type males may be due to avoidance behaviour exhibited by wild-type males). Mutant males aged individually for 5-7 days and then grouped together show high levels of head-to-head interactions 1 day after being grouped together. Mutant males show high levels of 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.

Mutation blocks the development of the muscle of Lawrence (MOL).

Males are more stimulated to court females and display more chaining behaviour than fru³ or fru⁴ males. All males that exhibit courtship do exhibit tapping behaviour (tapping of the female with the forelegs). Males, when presented with both sexes simultaneously, will perform vigorous and indiscriminate courtship directed at either sex. Chaining behaviour exhibited by males is displayed on the food surface and the walls of the glass vials. Mutant females are courted by wild-type males at normal levels.

Homozygous males do not mate with females. fru¹/fru^sat males mate with females, although less often than wild-type males, and they are fertile. Homozygous fru¹ and fru¹/fru^sat males form courtship chains. fru¹/fru^sat15 males show homosexual courtship activity.

Males court indiscriminately (exhibit high levels of male-male chaining), 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).

Df(3R)Cha^M5/In(3R)fru heterozygotes exhibit a muscle of Lawrence defect. In fru¹ homozygotes, fru¹/Df(3R)Cha^M5 and fru¹/Df(3R)P14 transheterozygotes muscle of Lawrence (MOL)-position fibres have nearly the same number of adult muscle nuclei as medial fibres, yet the mutants have only small sized MOL-position fibres. The number of muscle nuclei in MOL fibres is less than that in wild-type males. The number of myoblasts in unaffected.

Homozygous males are behaviourally sterile as they do not curl their abdomen for attempts at copulation, they also court other homozygous males and wild type males (chain behaviour). fru¹/fru^0-1 males show chain behaviour, although not as intensely as either fru¹ or fru^0-1 homozygotes, but are essentially normal in fertility.

Males court but do not mate with females; fru males court other males (especially when such flies also are homozygous for fru) and stimulate vigorous courtship on the part of fru or wild-type males. Mutant males produce volatile compounds different from those generated by normal males, on criteria of gas chromatography and bioassays of behavioral effects of these compounds; females appear to be unaffected by fru.

fru¹, tra¹ has abnormal courtship behavior phenotype

fru¹, tra2^B has abnormal courtship behavior phenotype

fru¹, tra¹ has muscle cell of male abdominal 5 muscle phenotype

fru¹, tra2^B has muscle cell of male abdominal 5 muscle phenotype