DNA damaging agents increase gadd153 (CHOP-10) messenger RNA levels in bovine preimplantation embryos cultured in vitro

DNA damage and other forms of stress are believed to be important factors i n reducing the efficiency of in vitro embryo transfer techniques in farm an imals. The expression of mRNAs from stress-responsive genes such as gadd153 (CHOP-10, ddit3) may provide a means of assessing the quality of embryos p roduced in vitro. Treatment of bovine granulosa cell cultures with the DNA- damaging agents, methyl methane-sulphonate (MMS) or sodium arsenite, induce d the expression of an mRNA, which hybridized with the hamster gadd153 cDNA . Part of the corresponding bovine cDNA was amplified by nested polymerase chain reaction (PCR), cloned, and sequenced. Using a sensitive reverse tran scriptase-PCR assay we have investigated the expression of gadd153 and beta -actin in blastocyst-stage bovine embryos treated with MMS or sodium arsen ite. Both agents produced an increase in the ratio of gadd153 mRNA relative to beta -actin. These results show that there are changes in gene expressi on in blastocyst-stage bovine embryos in response to genotoxic stress, sugg esting that an increase in gadd153 mRNA is a useful marker of DNA damage an d metabolic stress in preimplantation embryos.