BOVINE PARTHENOGENESIS IS CHARACTERIZED BY ABNORMAL CHROMOSOMAL COMPLEMENTS - IMPLICATIONS FOR MATERNAL AND PATERNAL CO-DEPENDENCE DURING EARLY BOVINE DEVELOPMENT
Qa. Winger et al., BOVINE PARTHENOGENESIS IS CHARACTERIZED BY ABNORMAL CHROMOSOMAL COMPLEMENTS - IMPLICATIONS FOR MATERNAL AND PATERNAL CO-DEPENDENCE DURING EARLY BOVINE DEVELOPMENT, Developmental genetics, 21(2), 1997, pp. 160-166
The present study was conducted to examine the karyotypes of parthenog
enetic bovine embryos arising from the application of standard oocyte
activation and diploidization methods. Bovine cumulus-oocyte complexes
were collected and matured in vitro For 24 hr prior to oocyte activat
ion with either 5 mu M ionomycin or 7% ethanol for 5 min. Groups of ac
tivated oocytes were further treated with 5 mu g/ml cytochalasin D or
1.9 mM 6-dimethylaminopurine (DMAP) for 6 hr. Cleavage varied signific
antly (P < .05) among the treatment groups with 68.0% of the ethanol-
and DMAP-treated oocytes dividing. Blastocyst development did not vary
with 18.4 +/- 2.5% of all treated oocytes progressing to this stage.
Blastocyst development did not occur in groups subjected to oocyte act
ivation alone. Blastocysts displayed haploid (2.3%), diploid (11.4%),
tetraploid (40.9%), octaploid (4.5%), and mixoploid chromosomal comple
ments (40.9%). Two-cell stage parthenogenotes resulting from ethanol o
r ionomycin treatment alone displayed haploid (66.7%), diploid (16.7%)
, tetraploid (4.2%), and mixoploid (12.5%) complements. Our results de
monstrate that diploid bovine parthenogenotes arising from these proce
dures are a minority, with the majority of parthenogenotes displaying
polyploid and mixoploid chromosomal complements. The events contributi
ng to these abnormal chromosomal complements occur as early as complet
ion of the first cell cycle, possibly linking these events with the ab
sence of a paternally supplied centrosome. (C) 1997 Wiley-Liss, Inc.