This proposal is for support of research to investigate the dictyosome-like structure (DLS), an organelle unique to male mammalian germ cells. DLS occur in spermatocytes and spermatids of the guinea pig and other species in large numbers and have been noted in testes of other species including man. The DLS superficially resemble conventional Golgi apparatus in that they are composed of stacks of 2-10(20) saccules of about 200 angstrom in thickness (membrane + lumen). DLS and Golgi apparatus coexist within the same cell. Readily distinguished from Golgi apparatus, DLS lack galactosyl and sialyl transferases, characteristic marker activities of Golgi apparatus, have intersaccular bridging elements, tubular structures, 100 angstrom in diameter, oriented orthoganol to the plane of the saccules, and an affinity, in electron microscope sections, for a phosphotungstic acid stain at low pH. DLS emerge as a new organelle, formed de novo, and unique to certain stages of spermiogenesis. Should DLS carry out some function related to acquisition of specific characteristics by sperm during their development, they would provide logical targets for development of new drugs applicable to control of fertility in the male. Additionally, understanding of the origins and fate of DLS will further our knowledge of organelle biogenesis by providing a model amenable to study by approaches not possible with other organelles such as Golgi apparatus where de novo origins are restricted to largely inaccessible developmental stages. The objectives of the research proposed are to study DLS of testis germ cells with emphasis on a potential role of DLS in formation of lysosomes and on the fate of DLS during stage IV of DLS morphogenesis. Here DLS decline in numbers during acrosome formation through the beginning of spermatid development. The work will include three aspects: 1) use of specific antibodies to clarify biogenetic (precursor/product) relationships among DLS, endoplasmic reticulum, plasma membranes, Golgi apparatus, and lysosomes, 2) to elucidate a potential DLS function, apparently shared with Golgi apparatus and lysosomes, in vesicle acidification and 3) to undertake a complete morphological and cytochemical analysis (including electron microscope immunocytochemistry) of late stages of DLS morphogenesis during which a functional role of DLS in the formation of lysosomes or lysosome-like structures is indicated. Throughout, an approach will be emphasized that combines information from cell fractionation and biochemical analyses with evidence from electron microscopy and cytochemistry.
