ben1 mutant males exhibit a significantly compromised resistance against treatment of paraquat, a herbicide that induced the formation of reactive oxygen species. Lifespan is reduced in ben1 mutant flies.
Embryos derived from homozygous females mated to wild-type males fail to develop; 72% contain only one nucleus, 12% contain 2-8 nuclei ad the remaining 16% have more than 8 nuclei. Only 2% hatch. 72% of the embryos have one acentrosomal spindle. These single spindles appear to be mitotic rather than meiotic; their presence requires fertilisation, they are positioned deep within the egg interior where the first mitotic spindle normally resides, polar bodies are present (indicating completion of meiotic divisions) and centrosomes are occasionally seen near the spindle. 80% of the embryos have a majority of spindles that are barrel-shaped and/or lacking centrosomes. Misaligned chromosomes are often seen.
Embryos derived from ben1/Df(1)KA10 females mated to wild-type males fail to develop; 40% contain only one nucleus, 43% contain 2-8 nuclei ad the remaining 17% have more than 8 nuclei. None of these embryos hatch. 50% of the embryos have a majority of spindles that are barrel-shaped and/or lacking centrosomes.
ben1 mutant tergotrochanteral motorneurons exhibit abnormally long, variable response latencies and do not follow 1:1 at high-frequency stimulation in 88% of responses. ben1/Df(1)HA92 transheterozygotes exhibit mutant synaptic responses in 93% of cases.
ben1 mutants exhibit an incipient chemical and gap junctional synapse.
Targeted expression of benScer\UAS.cUa in a ben1 mutant background, using Scer\GAL4OK307 and Scer\GAL80ts.αTub84B reveals the first 24 hours of pupal development to be critical for ben function in synaptic growth, despite synaptic growth occurring later during development.
Homozygous flies appear lethargic and uncoordinated, and do not show normal climbing behaviour. Adults are capable of flight, but will not initiate flight when dropped from a height. Viability is reduced, with approximately 60% of pupae failing to eclose successfully and dying during emergence. The giant fibre (GF) drives the tergotrochanteral muscle (TTM) at abnormally long latencies and the response fails completely at moderate frequencies in homozygous flies. Stimulation of the dorsal longitudinal muscle (DLM), and the three dorsoventral muscles (DVM I, II and III) by the GF appears normal. The terminal bend of the GF is abnormal. Gynandromorph analysis suggests that the GF phenotype is determined by the genotype of the head, which contains the cell body of the giant axon. Homozygous flies prefer visible light over UV light in a choice test, in contrast to wild-type flies. Photoreceptor R7 cell rhabdomeres appear deformed and displaced, and rhabdomeres of other photoreceptor cells may also show less severe abnormalities. The arrangement of the optic cartridges within the lamina is completely disrupted. Photoreceptor axons which reach the medulla make shallow disordered projections into it, and photoreceptor axon projections appear irregular and disordered after exiting the optic stalk.
TDT attachment sites vary. The muscle may be found in the wild type position, posterior to the intrascutal suture and displaced medially, anterior to the intrascutal suture or missing entirely. Muscle may also be reduced in size or split dorsally attaching to two separate sites on the scutum. Cytology of the TDT is also altered, muscles may have fibres that are swollen and stain abnormally, other fibres may have large, axially aligned holes. Attachment pattern of the DVMs is also altered. DVMs remain within their respective attachment regions or extend into the region normally occupied by an adjacent DVM. DVMs may be entirely missing. Many flies fail to eclose, dying during late pupal stages. Flies that do eclose show impaired motility. Flies can get stuck in their food, falling into the food causes their femurs to become swollen and bent.
Giant fibre (GF) fails to extend laterally along the tergotrochanteral jump muscle motorneuron (TTMmn) and instead terminates at the midline where it synapses with the peripherally synapsing interneuron (PSI). This results in a lack of direct synaptic connection between the GF and TTMmn.
Ethanol is capable of evoking a walk response at concentrations lower than 10%.