The present work is the first to document the variations in the concentration and the localization of the Ca2+-depen-dent actin filament-severing protein scinderin or adseverin, which reportedly shares a similar sequence, in testicular and epididymal cells during development, and in spermatozoa during and after their epididymal transit. It is also the first successful attempt to localize the protein in tissue sections.
Scinderin in the Testis
In the germ cells. Scinderin immunoreactivity is associated principally with a region corresponding with the sub-acrosomal space in the round spermatids and with the remodeling acrosome in the elongated spermatids. Because scinderin is a Ca2+-dependent actin filament-severing protein, these observations should be viewed in relation to other reports of actin in developing spermatids and spermatozoa.
It is generally believed that within the cell, actin exists in monomeric (G-actin) as well as in filamentous (F-actin) states or forms. Under conditions of intracellular ionic strength, all the cellular actin would be expected to be polymerized; the fact that this has been reported in neither Sertoli cells nor germ cells implies the presence in both cell types of factors that modify the state of actin during the germ cell’s development.