Protamine Withdrawal from Human Sperm Nuclei Following Heterologous ICSI into Hamster Oocytes
Authors: L. Jones, Estella; O. Zalensky, Andrei; A. Zalenskaya, Irina
Source: Protein and Peptide Letters, Volume 18, Number 8, August 2011 , pp. 811-816(6)
Publisher: Bentham Science Publishers
Abstract:During late stages of spermatogenesis in mammals, most histones bound to DNA are replaced by protamines (PRM), which results in formation of supercondensed and genetically inert sperm chromatin. At fertilization, mature spermatozoon penetrates oocyte and chromatin is remodeled “back” from nucleoprotamine to nucleohistone state.
While being crucial for activation of male genome and ultimately for initiation of embryonic development, this process is poorly studied, especially in humans. Data on model animals concerning PRM to histones exchange post fertilization are few and contradictory.
As direct experimentation with human embryos is impossible due to ethical, legal and technical reasons, we evaluate the timing and mode of PRM removal in a heterologous ICSI system using hamster ova injected with human sperm. Localization of human PRM 1 and 2 in hybrid zygotes was established using immunofluorescence. We observed a marked zygote to zygote variability in male pronuclei size for any time point post ICSI and demonstrated that PRM removal correlates with the developing pronuclei area rather than time after injection. Overall, the disappearance of protamines from sperm is rather rapid and most likely completed within 1 hr. We propose that the critical characteristic influencing PRM removal after heterologous fertilization is the intrinsic heterogeneity of the human sperm population. The same yet unexplored variance may be one of the reasons for canceled, delayed or aberrant early embryonic development during natural or artificial fertilization in humans.
Keywords: Antiserum; Fertilization; Histones; Immunolocalization; Mitosis; Non-decondensed sperm; Spermatozoa; Spermiogenesis; germ cells; heterologous ICSI; homogeneous PRM; immunofluorescence; male pronuclei; nucleoprotamine; oocytes; ooplasm; protamine; sperm; spermatogenesis; zygote
Document Type: Research Article
Publication date: August 2011
- Protein & Peptide Letters publishes short papers in all important aspects of protein and peptide research, including structural studies, recombinant expression, function, synthesis, enzymology, immunology, molecular modeling, drug design etc. Manuscripts must have a significant element of novelty, timeliness and urgency that merit rapid publication. Reports of crystallisation, and preliminary structure determinations of biologically important proteins are acceptable. Purely theoretical papers are also acceptable provided they provide new insight into the principles of protein/peptide structure and function.