Chromatin condensation in hamster sperm: A flow cytometric investigation

Abstract

In this study we have used acridine orange staining, as described by Evenson (1990), to follow changes in DNA packaging as they occur in hamster spermatozoa which have left the testis and are undergoing maturation in the epididymis. Measurement of the green and red fluorescent intensities of hamster sperm nuclei by flow cytometry demonstrated a decrease in acridine orange binding to DNA as sperm made their way from proximal corpus epididymis to the vas deferens. Using sperm from the cauda epididymis of the mature hamster as the standard, a method was developed for estimating the % of cells in a given sample that have matured with regard to DNA packaging. Staining with bromobimane was used to determine the extent of sulfhydryl oxidation in the nuclei. It was seen that sulfhydryl oxidation occurred mainly in the cauda epididymis whereas another process in chromatin condensation occurred earlier, during sperm passage through the caput epididymis. This earlier process could be mimicked by incubating sperm nuclei with alkaline phosphatase, suggesting that it consists of removal of phosphate in protamine.

Chromatin condensation during spermiogenesis in the golden hamster (Mesocricetus aureus): A flow cytometric study

“…Similar findings for other rodents were reported by Evenson et al (1989). The final step of stabilization of the hamster protamine-DNA complex in the epididymis includes oxidation of SH bonds in protamine to form SS bonds (Yossefi et al, 1994).…”

“…In previous studies we have demonstrated further chromatin condensation in spermatozoa during passage through the epididymis (Yossefi et al, 1994;Golan et al, 1996Golan et al, , 1997. Recent work (Golan et al, 2000) has shown that only the final 12% of the chromatin condensation in the hamster occurred in the epididymis.…”

Head morphometry and chromatin instability in normal boar spermatozoa and in spermatozoa with cytoplasmic droplets

“…The positive correlation between percent cytoplasmic droplets and chromatin heterogeneity can possibly be explained by the immaturity of cells when they were ejaculated. More frequent semen collection results in less time for cell maturation, and this probably influences the completion of chromatin condensation (Yoseffi et al, 1994;Hingst et al, 1995;Golan et al, 1996) as well as cytoplasmic droplet migration (Flowers, 2004). Also important is that retention of droplets, primarily proximal droplets, correlates strongly with production of reactive oxygen species (ROS) in semen (Gomez et al, 1996).…”

Expression of mammalian spermatozoal nucleoproteins

“…According to recent data, a 34-kDa selenoprotein that is present only in the sperm nuclei acts as a protamine thiol peroxydase, and therefore appears to be necessary for protamine thiol cross-linking during sperm maturation (Pfeifer et al, 2001). In man (Saowaros and Panyim, 1979), as in the rat (Calvin et al, 1973;Calvin, 1981;Huang and Nieschlag, 1984;Shalgi et al, 1989), mouse (Balhorn et al, 1984), guinea-pig , hamster (Yossefi et al, 1994), and boar (Tobita et al, 1983), evaluation of the number of disulfide bonds in protamines from mature spermatids and epididymal spermatozoa has shown that the stabilization of the chromatin starts in the testis and then develops with passage from the head to the tail of the epididymis. Ultrastructural image cytometry of human sperm nuclei has established that the overall level of chromatin condensation significantly increases during epididymal transit, thus reflecting the augmentation in the number of disulfide bridges (Auger and Dadoune, 1993).…”