Submission Number: IRI-4-25-7

Abstract Number: 374

GENETIC EFFECTS ON POSTIMPLANTATION VIABILITY AND CONCEPTUS WEIGHT OF CHIMERIC MOUSE EMBRYOS.

IN Vagyna, OV Anoprienko, AV Evsikov and AP Solomko

Institute of Molecular Biology and Genetics, Ukrainian NAS, Kiev, Ukraine ¹

Abstract:
In order to evaluate the genetic effects on developmental potential of chimeric mouse embryos during postimplantation period, we have studied the development of chimeras between BALB/c embryos and hybrid C57Bl/6xBALB/c (F1; 50% BALB/c genotype) or CB6F1xBALB/c (F2; 75% BALB/c genotype) embryos. After embryo disaggregation at the 8-cell stage, we have reconstructed these types of embryos: F1<->BALB/c and F2<->BALB/c ("true" chimeras), F1<->F1, F2<->F2 and BALB/c<->BALB/c (control). Although in vitro development of these embryos was retarded comparing to controls, 70-85% of them reached the expanded blastocyst stage by 113 h post-hCG injection. These blastocysts and unmanipulated BALB/c, F1, F2 and ICR blastocysts were transferred to the oviducts of day 0 pseudopregnant ICR females. On day 16 of pregnancy, females were killed and the numbers of implantation sites, live embryos, fetal and placental weights were calculated.

Implantation of all manipulated embryos, except F1<->BALB/c, was significantly (P>0.99) worse than in controls. BALB/c<->BALB/c embryos gave no live fetuses, but the average fetal wheigts of manipulated embryos of other types were estimated. There was no significant differences in average weights of manipulated embryos of all groups, except F1<->BALB/c, comparing to control F1, F2 and BALB/c fetuses. The weight of embryos and placentas in F1<->BALB/c group was significantly (P>0.95) higher, than in F2<->BALB/c, F1<->F1, F2<->F2 and control BALB/c and F2 groups, and even higher (unsignificantly, P=0.89) than in F1 embryos. These results suggest that the viability of chimeric embryos depends on the genotype of their "hybrid" part, which defines their adaptivity to an alien genetic background of their ICR foster mothers. The composition of F1<->BALB/c fetuses is presently analysed using GPI polymorphism analysis.

Keywords: chimera, embryo viability, fetal weight

This abstract is being presented at: 8:00 AM in session:
Preimplantation Embryo/Fetus