Homozygous third larval instar eye imaginal discs show a number of defects in morphology and glial cell migration. In 9% of discs there is a duplication of the morphogenetic furrow and the corresponding field of photoreceptor neurons at 90[o] to the normal eye field. In 62% of discs, glial cells are found anterior to the morphogenetic furrow and appear to migrate in a broad stream onto the eye imaginal disc. In 11% of discs, only a relatively thin stream of of glial cells overshoot anterior to the morphogenetic furrow. In another 11% of discs, glial cells are found anterior to the position they are found in wild type (including sometimes crossing the morphogenetic furrow), but do not form a stream of cells anterior to the morphogenetic furrow. 7% of the discs appear wild type. Almost all of the ectopically positioned glial cells are perineurial glia. The homozygous discs generally contain more glial cells than normal, which is particularly apparent in young eye imaginal discs with 0-5 rows of photoreceptors cells. The defects in glial cell migration are seen in early third larval instar eye discs, with glial cells migrating far onto the undifferentiated epithelium (in wild type, glial cell migration from the optic stalk to the eye disc is inhibited at the beginning of the third instar stage). The shape of the carpet glial cells is severely affected in the mutants and they fail to extend over the eye field.
Wrapping glia cells are found at a lower frequency in homozygous glial clones in the eye disc compared with wild-type clones, whereas the frequency of perineurial glial cells appears higher in the mutant clones. Homozygous carpet glia cells are reduced in size compared to wild-type cells.
65% of spinEP822/spin10403 stage 14 egg chambers show persisting nurse cell nuclei, compared to 7% in controls. 52% of egg chambers display a dumpless phenotype where nurse cell cytoplasm has not been transferred to the oocyte.
Mutation is lethal at the pharate pupal stage. spin10403/spink09905 animals show a significant increase in bouton number at the larval neuromuscular junction (assayed at muscles 6/7 in hemisegment A3) compared to wild type. Quantal content at the neuromuscular junction is decreased by approximately 50% compared to wild type in spin10403/spink09905 animals. Quantal size is unaffected. Only 23% of spin10403/spink09905 animals are adult viable.
spin1/spin10403 females show a profound decrease in mating success compared to wild-type females when paired with wild-type males. The time spent by the wild-type male performing unilateral wing vibration during a 10 minute observation (the SAPI - sex appeal parameter index) is almost identical for males paired with spin1/spin10403 or wild-type females. spin1/spin10403 females show a number of rejection behaviours when paired with wild-type males, including fending, kicking, flicking, curling, punching and decamping, although extrusion is rarely seen. In addition, the mutant females show spreading behaviour (they raise their abdomens while spreading their vaginal plates), which is not seen in wild-type females. The mutant females show a high frequency of punching behaviour, which is rare amongst wild-type females. Homozygous animals show autofluorescence in the central nervous system from the larval stage onwards.