Submission Number: ALE-4-17-27

Abstract Number: 511

PLACENTAL EXPRESSION OF VASCULAR ENDOTHELIAL GROWTH FACTOR AND PLACENTAL GROWTH FACTOR mRNA IN NUCLEAR-CLONED BOVINE PREGNANCIES.

Alexandra JAE De Lille, Russell V Anthony* and George E Jr Seidel*

Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO, USA. ¹

Abstract:
Pregnancy losses exceed 50% during the first trimester of gestation in pregnancies derived from nuclear-cloned embryos. Aberrant placental vascular development could impair placental function and nutrient transfer between mother and fetus. We evaluated concentrations of VEGF and PlGF mRNA, growth factors involved in placental angiogenesis, in intercotyledonary allantochorion and cotyledonary tissue at 45 days of gestation. Angus heifers were artificially inseminated with Brangus semen to produce control pregnancies. Brangus cloned embryos were produced by bisecting oocytes and fusing each half with a blastomere from a 16+ -cell embryo (Wilson et al., Anim Reprod Sci 38:73). Clutches of cloned embryos were enlarged by serial nuclear transplantation. After fusion, embryos were transferred surgically to sheep oviducts and recovered and frozen in 1.5M ethylene glycol 6-7 days later. Frozen-thawed cloned embryos (n=29) were transferred nonsurgically into beef heifers. Placental membranes were collected by transcervical, nonsurgical aspiration, 45 days post estrus. Cotyledons and intercotyledonary allantochorion were dissected and snap frozen in LN₂. Total cellular RNA from 4 control and 6 cloned pregnancies was isolated by CsCl gradients. PlGF, VEGF and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) cDNAs were radiolabeled for Northern hybridizations. No difference (P>.1) in VEGF or PlGF mRNA concentration was observed between control and cloned tissues when normalized for GAPDH mRNA concentration. VEGF/PlGF ratios also were not different (P>.1) between groups. Although VEGF and PlGF mRNA were detected, it may be too early to observe differences due to minimal placentome microvillus development at this stage.

Keywords: VEGF, PLGF, Bovine, Cloning, Placenta.

This abstract is being presented at: 8:00 AM in session:
Implantation and Early Development