The incidence of cytoplasmic fragmentation in mouse embryos in vitro is not affected by inhibition of caspase activity.
OBJECTIVE
To investigate the relationship between cytoplasmic fragmentation and caspase activity in the mouse embryo.


METHODS
Experimental laboratory study.


METHODS
University gynacology unit.


METHODS
One-cell zygote of mouse (MF1 x BALB/c).


METHODS
Mouse embryos were treated with caspase inhibitors: benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone (z-VAD-fmk) and benzyloxycarbonyl-Asp-glu-Val-Asp-fluoromethyl ketone (Z-DEVD-fmk).


METHODS
Morphological development of the embryo, proportion of fragmented embryos, caspase-3-like activity, DNA breakage, and phosphatidylserine exposure in blastomeres.


RESULTS
The proportion of embryo reaching two-cell, three- to four-cell, and morula stage at 48, 72, and 96 hours after hCG administration, respectively, were comparable between the control embryos and those treated with either z-VAD-fmk or z-DEVD-fmk, at three concentrations (10 microM, 50 microM, and 200 microM). Although the inhibitors suppressed the caspase-3-like activity in the embryo fragment before compaction and decreased DNA breakages, there was no statistically significant difference in the percentage of fragmented embryo between the control and those treated with caspase inhibitors. The inhibitors did not affect the incidence of phosphatidylserine exposure in the blastomere of the treated embryos.


CONCLUSIONS
Cytoplasmic fragmentation in precompaction mouse embryos is not a consequence of caspase-related apoptosis.
Xu
J
J
Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
Cheung
T
T
Chan
S T
ST
Ho
P
P
Yeung
W S
WS
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003593:Cytoplasm / Q000201:enzymology / Q000473:pathology; D053938:DNA Fragmentation / Q000502:physiology; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005260:Female; D020287:In Situ Nick-End Labeling; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009842:Oligopeptides / Q000494:pharmacology; D010718:Phosphatidylserines / Q000032:analysis; D011247:Pregnancy; D011897:Random Allocation; D013194:Staining and Labeling; D015053:Zygote / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology
D000590:Amino Acid Chloromethyl Ketones; D017304:Annexin A5; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D007527:Isoenzymes; D009842:Oligopeptides; D010718:Phosphatidylserines; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases