pex107 mutants exhibit reduced female fertility and male sterility. pex107 mutant testes contain many spermatocytes and some 'cotton ball'-like spheres but completely lack elongated spermatid bundles and mature sperm. The mutant testes appear much thinner and longer on the seventh day after eclosion than they do immediately after eclosion.
pex107 mutants display growth defects, with mutants exhibiting a 2-day delay in eclosion.
pex107 mutant testes do not contain hardly any normal mature spermatocytes. Instead, only a few fused spermatocytes with condensed chromosomes are found. In addition, there are more spermatocytes in pex107 mutants than wild-type. In pex1010 mutants, cysts of 16 spermatocytes without cell-cell boundaries and with large round nuclei are present. This suggests that the spermatocyte growth stage is defective. The majority of spermatocytes do not mature, and some are fused. the fused spermatocytes are able to continue develop but exhibit profound defects in spermatid differentiation. Only a few round spermatids are found compared with wild-type and they often exhibit four or more nuclei associated with a single enlarged mitochondrial derivative, indicating a failure of cytokinesis during meiotic division. Chromosome segregation appears unaffected. Unlike wild-type testes, which have very long spermatid bundles, the few spermatids in pex107 mutants, presumably from a cyst, form 'cotton ball'-like spheres. Thus pex107 mutant spermatids can initiate the extension of sperm tails, but this process is abnormal.
pex107 mutant spermatocytes go through G1/S phase normally but do not reach the G2/M transition.
Peroxisomal membrane protein targeting and peroxisomal structures appear quite normal in pex107 mutants.
Growing pex107 mutants on medium to which 2.5% VLCFA has been added results in a significant enhancement of the pex107 testis phenotype compared to pex107 flies grown on non-supplemented food. In contrast, adding 2.5% LCFA to the food does not enhance the testis phenotype.