Stage-specific synthesis and fucosylation of plasma membrane proteins by mouse pachytene spermatocytes and round spermatids in culture

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Abstract
Little is known about the ability of mammalian spermatogenic cells to synthesize plasma membrane components in the presence or absence of Sertoli cells. In this study, purified populations (> 90%) of pachytene spermatocytes or round spermatids were isolated by unit gravity sedimentation and cultured for 20-24 h in the presence of [35S]methionine or [3H]fucose. Cell viabilities remained over 90% during the course of these experiments. Plasma membranes were purified from these cells and analyzed by two-dimensional gel electrophoresis. Qualitatively, the same plasma membrane proteins were synthesized by both cell types with the exception of the major Concanavalin A-binding glycoprotein, p151; the synthesis of p151 is greatly diminished or inhibited after meiosis. [3H]Fucose was incorporated into at least 6 common glycoproteins of both cells. Eight components fucosylated with molecular weights from 35,000 to 120,000 were specific to pachytene spermatocyte membranes. One fast-migrating fucosylated component may represent an uncharacterized lipid whose synthesis is terminated after meiosis. Round spermatids specifically fucosylated two components with molecular weights of 45,000 and 80,000. These results demonstrate the viability of germ cells of the male mouse in short-term culture and show that they are capable of synthesizing and fucosylating plasma membrane components in the absence of Sertoli cells.