Degradation of sperm histones in vitro by cytoplasm of the sea urchin egg

Impact of kudzu and puerarin on sperm function

The goal of this study was to investigate the impact of kudzu (Pueraria mirifica) and the isoflavone puerarin in functional toxicological tests on spermatozoa and to assess the affinity of extracts and pure isoflavones for estrogen receptor (ER)-alpha and -beta (ERα, ERβ) in receptor binding assays. Capacitation, acrosome reaction and chromatin decondensation in spermatozoa were analyzed using microscopic analysis. Kudzu, but not puerarin, reduced motility of sperm. Puerarin reduced the percent spontaneous acrosome reaction in spermatozoa. The pathways used by kudzu that affect sperm function are not fully mirrored by puerarin. Puerarin, kudzu and its other phytoestrogenic components displayed preferential affinity for ERβ, however the diverse effects of kudzu and puerarin on sperm function implicate the involvement of multiple signaling systems.

In vitro decondensation of the sperm chromatin in Holothuria tubulosa (sea cucumber) not affecting proteolysis of basic nuclear proteins

Sea urchin and sea star oocyte extracts contain proteolytic activities that are active against sperm basic nuclear proteins (SNBP). This SNBP degradation has been related to the decondensation of sperm chromatin as a possible model to male pronuclei formation. We have studied the presence of this proteolytic activity in Holothuria tubulosa (sea cucumber) and its possible relationship with sperm nuclei decondensation. The mature oocyte extracts from H. tubulosa contain a proteolytic activity to SNBP located in the macromolecular fraction of the egg-jelly layer. SNBP degradation occurred both on sperm nuclei and on purified SNBP, histones being more easily degraded than protein Ø(o) (sperm-specific protein). SNBP degradation was found to be dependent on concentration, incubation time, presence of Ca(2+), pH, and this activity could be a serine-proteinase. Thermal denaturalization of the oocyte extracts (80 degrees C, 10-15 min) inactivates its proteolytic activity on SNBP but does not affect sperm nuclei decondensation. These results would suggest that sperm nuclei decondensation occurs by a mechanism different from SNBP degradation. Thus, the sperm nuclei decondensation occurs by a thermostable factor(s) and the removal of linker SNBP (H1 and protein Ø(o)) will be a first condition in the process of sperm chromatin remodeling.

Predictive value of chromatin decondensation in vitro on fertilization rate after intracytoplasmic sperm injection (ICSI)

This study was undertaken to identify the relationship between sperm chromatin decondensation after incubation with sodium dodecyl sulphate (SDS) and ethylene diamine tetra acetic acid (EDTA), or heparin at various points of time. Likewise, this study will determine chromatin stability within definite time intervals, chromatin decondensation after intracytoplasmic sperm injection (ICSI), and whether chromatin decondensation in vitro could be used as a predictive test for fertilization capability after ICSI. Sixty-five infertile couples undergoing ICSI therapy were included in this prospective study. Male factor infertility was the main indication for inclusion. One millilitre from each semen sample after washing was mixed with SDS-EDTA (group 1) or SDS/heparin (group 2) and incubated for 120 min. Many smears were made within 10 min of mixing the spermatozoa with detergent and the reducing agents and at the following points of time 30, 60 and 120 min and after 24 h. Chromatin decondensation was evaluated after staining with acridine orange (AO). The mean percentage of uncondensed chromatin of spermatozoa in the semen sample in the first group before addition of SDS/EDTA was 26.1 +/- 19.0 and 22.3 +/- 18.9% in the second one. After incubation of spermatozoa for 30, 60 and 120 min and 24 h, the chromatin decondensation increased in the first group to 64.0 +/- 28.6, 83.0 +/- 21.1, 87.9 +/- 14.6, 92.1 +/- 16.2 and 98.0 +/- 6.75%, respectively. The corresponding values in the second group were 69.5 +/- 29.9, 78.6 +/- 22.4, 86.9 +/- 17.1, 95.13 +/- 6.5 and 98.3 +/- 5.6%. On the other hand, no correlations were found between the chromatin decondensation or chromatin decondensation rate in vitro and the fertilization rates in all investigated groups. In conclusion, neither the chromatin decondensation ability in vitro nor the rate of chromatin decondensation between various points of time after using SDS/EDTA, SDS/heparin could predict the chromatin decondensation of spermatozoa (fertilization capability) after ICSI.