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Telomerase Activity in Early Bovine Embryos Derived from Parthenogenetic Activation and Nuclear Transfer¹

^a Department of Animal Science, University of Connecticut, Storrs, Connecticut 06269

ABSTRACT

This study examined the telomerase activity in preimplantation bovine embryos derived from either parthenogenetic activation or nuclear transfer. Telomeres are the DNA-protein structures located at the ends of eukaryotic chromosomes. Telomerase is the ribonuclear enzyme that helps to restore telomere length by synthesizing telomeric DNA repeat (5'-TTAGGG-3') from its own RNA template. Without telomerase activity, telomeres shorten with each cell division through conventional DNA replication. In most mammalian species, telomerase activity is present in germ cells but not in somatic cells. Previously, we reported the dynamics of telomerase activity in bovine in vitro fertilized (IVF) embryos. In the present study, we examined the telomerase activity in bovine embryos derived either from parthenogenetic activation or somatic cell nuclear transfer (i.e., cloning). Embryos from both sources were harvested at different stages, from zygote to blastocyst. Telomerase activity in embryos derived from parthenogenetic activation and nuclear transfer showed a dynamic profile similar to that of those derived from IVF. Telomerase activity was detected in embryos at all stages examined, with the highest level in the blastocyst stage, regardless of the method of embryo production.

FOOTNOTES

First decision: 5 September 2000.

¹ Supported in part by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under agreement 96-35203-3268 and by a grant from Connecticut Innovations, Inc. This paper is a scientific contribution (number 1975) of the Storrs Agricultural Experiment Station of the University of Connecticut.

² Correspondence: X. Jerry Yang, Department of Animal Science, University of Connecticut, 1390 Storrs Rd. U-4163, Storrs, CT 06269-4163. FAX: 860 486 0534; jyang{at}canr.uconn.edu

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