SINGLE BLASTOMERES WITHIN HUMAN PREIMPLANTATION EMBRYOS EXPRESS DIFFERENT AMOUNTS OF MESSENGER-RIBONUCLEIC-ACID FOR BETA-ACTIN AND INTERLEUKIN-1 RECEPTOR-TYPE-I

Gaining knowledge about the physiological timetable of gene expression during preimplantation embryo development is crucial, and a better un derstanding of cytokine and growth factor expression in early embryoni c development could lead to improved in vitro culture conditions and e nhance in vitro fertilization implantation rates. Our aim was to detec t the patterns and levels of two messenger ribonucleic acids [mRNAs; b eta-actin and interleukin-1 receptor type I (IL-1R tI)] in single huma n blastomeres by RT-nested PCR and to compare possible variations in t he gene expression both between different embryos and in multiple blas tomeres within the same embryo. Single blastomeres from nine human tri pronucleic preimplantation embryos were examined by one round of RT an d two rounds of nested competitive PCR. beta-Actin mRNA was detected i n each blastomere, and IL-1R tI mRNA was found in 72% of the blastomer es examined. beta-Actin was expressed at a level of 511-12185 molecule s of complementary DNA/blastomere, and IL-1R tI was expressed at a lev el of 2-290 molecules of complementary DNA/blastomere. Our results sug gest that the mRNA pattern of an embryo cannot be reliably quantitated from the mRNA pattern afa single blastomere and therefore imply limit ations for the use of this method for preimplantation diagnosis.