Chromatin condensation, cysteine-rich protamine, and establishment of disulphide interprotamine bonds during spermiogenesis of Eledone cirrhosa (Cephalopoda).

摘要: During spermiogenesis in Eledone cirrhosa a single protamine substitutes for histones nuclei of developing spermatids. This protein displays peculiar primary structure. It contains 22.6 mol% cysteine residues (19 cysteines 84 residues). makes it the most cysteine-rich known. The proportion basic is relatively low (arginine 36.9 mol%, lysine 19.0 mol%). E. condenses spermiogenic chromatin pattern which comprises fibres with progressively larger diameter and lamellae that finally undergo definitive coalescence. We have also performed study estimates number interprotamine disulphide bonds formed during process condensation by means sequential disappearance MMNA (monomaleimido-nanogold) labelling. first step spermiogenesis, protamines are found spread over very slightly condensed their reactive state (protamine-cys-SH). From this stage established progressive way. First they inside fibres. Subsequently, participate mechanism fibre coalescence finally, last remaining free -SH groups form bonds, thus promoting stabilization nucleoprotein complex ripe sperm nucleus.