Figure 5.—

levy mutants exhibited vacuolization of the optic lobes and brain, but were rescued by transformation with the wild-type gene. Epon-embedded horizontal brain sections were cut from head capsules of adults kept at 29° after eclosion. Slices through the heads of 7-day-old wild type (CS) (A) and levy transformant (C) are shown for comparison to that from the head of levy¹ mutant (B). Swiss cheese-like holes appeared in the brain and optic lobes in 7-day-old levy¹ mutants (inset). These cytological lesions also appeared in the brains and optic lobes of 7-day-old transformant control flies (data not shown). Neurodegeneration occurred in age-dependent manner (D), being absent in CS flies aged for 1 day or 6 days, and in levy¹ flies aged for 1 day. On the other hand, 19 of 20 levy¹ flies aged for 6 days showed clear neurodegeneration. Serial sections from paraffin processed flies were obtained from levy¹/levy² (E) and levy¹/levy³ (F) flies after aging them for 6 days at 29°. Neurodegeneration was observed in flies from both strains, consistent with the phenomenon seen in levy¹ mutants.