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Formation of the sea urchin male pronucleus in vitro: Membrane‐independent chromatin decondensation and nuclear envelope‐dependent nuclear swelling
Author(s) -
Collas Philippe,
Poccia Dominic L.
Publication year - 1995
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080420114
Subject(s) - biology , cytoplasm , microbiology and biotechnology , chromatin , nuclear membrane , swelling , pronucleus , biophysics , lamin , cell nucleus , sea urchin , nuclear lamina , inner membrane , nucleus , biochemistry , nuclear protein , dna , zygote , materials science , embryo , embryogenesis , gene , transcription factor , mitochondrion , composite material
We demonstrate that complete sea urchin male pronuclear development in vitro is a two‐step process involving membrane‐independent chromatin decondensation and nuclear envelope‐dependent pronuclear swelling. In the absence of cytoplasmic membrane vesicles (MVs), permeabilized sperm chromatin decondenses into a spherical nucleus of ≈4 μm in diameter. Pronuclear swelling to ≈7 μm requires an intact nuclear envelope, and the degree of swelling is limited by the amount of MVs assembled on the chromatin. Furthermore, after a nuclear envelope is formed, swelling can occur in the absence of additional cytoplasmic MVs. Nuclear swelling also requires ATP hydrolysis, Ca 2+ and cytosolic factors, some of which are sensitive to heat and to the sulfhy‐dryl alkylating agent, N ‐ethylmaleimide. The requirement for a nuclear envelope and the rate of pronuclear swelling are consistent with previous in vivo observations. © 1995 wiley‐Liss, Inc.