Formation of the sea urchin male pronucleus in vitro: membrane-independent chromatin decondensation and nuclear envelope-dependent nuclear swelling.
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 approximately 4 microns in diameter. Pronuclear swelling to approximately 7 microns 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, Ca2+ and cytosolic factors, some of which are sensitive to heat and to the sulfhydryl alkylating agent, N-ethylmaleimide. The requirement for a nuclear envelope and the rate of pronuclear swelling are consistent with previous in vivo observations.
Collas
P
P
Department of Food Science, Agricultural University of Norway, Aas, Norway.
Poccia
D L
DL
D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000502:physiology; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D048429:Cell Size; D002843:Chromatin / Q000648:ultrastructure; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro; D006358:Hot Temperature; D008297:Male; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D012617:Sea Urchins / Q000502:physiology* / Q000648:ultrastructure; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure*
D002843:Chromatin; D009687:Nuclear Proteins; D000255:Adenosine Triphosphate; D005033:Ethylmaleimide; D002118:Calcium