MALE PRONUCLEI FORMATION RELEASE OF PHOSPHORYLATION OF HISTONE H-3 DURING DECONDENSATION OF HUMAN SPERM NUCLEI ACTIVATED INVITRO BY HEPARIN

The release and phosphorylation/dephosphorylation mechanisms of human spermatozoa histone during nuclei in vitro decondensation by heparin was studied. Washed sperm cells were incubated in the presence of P-32 and in the absence or presence of heparin. The results showed an increase in the incorporation of P-32 of 20 times greater in the presence of heparin than in the absence of heparin (the control sample). In some cases the incorporation of P-32 into histones was confirmed by its isolation. To validate these results a phosphorylation kinetic of isolated sperm histone, used as a substrate, was performed. The amount of P-32 was not a linear function of time, and maximal phosphorylation was reached in 60 min. A measurement of P-32 incorporated as a function of the amount of histone, shows a linear relationship of up to 50-mu-g of protein, with a rapid saturation thereafter with the incorporation of 220 nm and with a KD = 442 x 10(-6) mol/L. P-32 incorporation, independent of exogenous cAMP, was related to alkaline pH but was totally dependent on temperature-with a maximum of 37-degrees-C. The only histone released was histone H-3. Phosphorylation/dephosphorylation is involved during male pronuclei formation.