EFFECT OF HEPARIN-REDUCED GLUTATHIONE ON HAMSTER SPERM DNA UNPACKING AND NUCLEAR SWELLING

This study examined the kinetics of sperm nuclear decondensation induc ed by the action of physiological concentrations of heparin and glutat hione in hamster sperm nuclei as a chromatin model that contains prota mine P1 and P2. Sperm suspension was incubated at different temperatur es (37, 40, 43, and 46 degrees C) in media, keeping constant the conce ntration of either heparin or GSH and increasing concentrations of the other reagent. Spermatozoa nuclei without any treatment, incubated fo r 72 h, appear densely condensed. Swelling of hamster spermatozoa nucl ei was observed after 30 min of incubation in the presence of efficien t concentrations of heparin-GSH. The extent of this time lag was signi ficantly reduced at higher temperatures. DNA presence was verified by the use of ethidium bromide, acridine orange, and Feulgen stain. Phase -contrast microscopy shows that nuclear decondensation begins at the e quatorial levels, with DNA highly condensed at the acrosome pole, and the basal pole as the DNA attachment point. Electron microscopy observ ations showed that hamster sperm nuclei initiates its decompaction at the peripheral regions and this behavior remains until late stages of decondensation; nevertheless, the chromatin is organized into ''hub-li ke'' nuclear bodies that measured 10-100 nm in diameter, joined by a n etwork of chromatin fibers with apparent reduction in number. At the d econdensation full stage, the network seems to be wide open with a red uced number of hub-like nuclear bodies present in the interlace. DNA i s not organized into topologically constrained loop domains and is att ached to the basal plate instead of to the nuclear matrix or any other structure.