Measurement of histone mRNA transcript abundance in Xenopus oocytes by a quantitative primer extension assay

A quantitative primer extension method was used to measure the mass of histone gene transcripts in mature oocytes of the amphibian Xenopus laevis. The procedure, using a large excess of gene‐specific oligonucleotide primer and continuous incorporation of a radiolabeled deoxynucleoside triphosphate precursor, is more sensitive and quantitative than primer extension assays employing end‐labeled primers. It was determined that there are stoichometric amounts, approximately 2 × 10 8 copies, of mRNA for each of the five major histone gene classes in mature Xenopus oocytes. These observations are consistent with a model whereby transcription of these genes is coordinately regulated in a cell cycle‐independent manner during amphibian oogenesis.