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 stoichiometric amounts, approximately 2 X 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.