Egg activation events are regulated by the duration of a sustained [Ca2+]cyt signal in the mouse.
Although the dynamics of oscillations of cytosolic Ca2+ concentration ([Ca2+]cyt) play important roles in early mammalian development, the impact of the duration when [Ca2+]cyt is elevated is not known. To determine the sensitivity of fertilization-associated responses [i.e., cortical granule exocytosis, resumption of the cell cycle, Ca2+/calmodulin-dependent protein kinase II (CaMKII) activity, recruitment of maternal mRNAs] and developmental competence of the parthenotes to the duration of a [Ca2+]cyt transient, unfertilized mouse eggs were subjected to a prolonged [Ca2+]cyt change for 15, 25, or 50 min by means of repetitive Ca2+ electropermeabilization at 2-min intervals. The initiation and completion of fertilization-associated responses are correlated with the duration of time in which the [Ca2+]cyt is elevated, with the exception that autonomous CaMKII activity is down-regulated with prolonged elevated [Ca2+]cyt. Activated eggs from 25- or 50-min treatments readily develop to the blastocyst stage with no sign of apoptosis or necrosis and some implant. Ca2+ influx into unfertilized eggs causes neither Ca2+ release from intracellular stores nor rapid removal of cytosolic Ca2+. Thus, the total Ca2+ signal input appears to be an important regulatory parameter that ensures completion of fertilization-associated events and oocytes have a surprising degree of tolerance for a prolonged change in [Ca2+]cyt.
Ozil
Jean-Pierre
JP
Unité de Biologie du Développement et Reproduction, INRA, 78352 Jouy-en-Josas cedex, France. Jean-Pierre.Ozil@jouy.inra.fr
Markoulaki
Styliani
S
Toth
Szabolcs
S
Matson
Sara
S
Banrezes
Bernadette
B
Knott
Jason G
JG
Schultz
Richard M
RM
Huneau
Daniel
D
Ducibella
Tom
T
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D020013:Calcium Signaling / Q000502:physiology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006657:Histones / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010063:Ovum / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D020554:Sperm Injections, Intracytoplasmic; D013997:Time Factors
D006657:Histones; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium