investment cone (with mlt1)
Individualisation complexes assembled around spermatid nuclear bundles are intact in homozygous, mltG18151/mlt1, mltG18151/mltEY02157 and mltG18151/Df(2R)BSC350 testes, but progressed individualisation complexes (those no longer co-localising with the nuclear bundle) are often disrupted, having one or more investment cones out of register. Sleeves of F-actin associated with highly condensed spermatid bundles at the most basal end of the testis tubule are sometimes seen.
Whereas in wild type all 64 investment cones of a spermatogenic cyst stay together and usually move in synchrony along the axoneme bundle, they often lose contact and disperse in mltG18151/mltG18151 mutants.
Courtship display and success is reduced in mltG18151/mltG18151 males.
Sperm function per se is not significantly affected by mutation of mlt, as very few offspring result from a cross of mltG18151/mltG18151 females to mlte00818/mlte00818 males, whereas normal numbers of progeny genotypes result from a cross of mltG18151/mltG18151 females to mlte00818/CyO males.
Although the P{EP}mltG18151 insertion maps within both the CG12214 annotation and an intron of KCNQ (nested genes, CG12214 is entirely within a large intron of KCNQ), complementation analysis indicates that the "mlt" mutant phenotype caused by this insertion (spermatid individualisation defects) is due to an effect on CG12214 and not on KCNQ.