Abstract
Messenger RNA has been extracted from oocysts of Eimeria maxima. Using the techniques of in vitro translation and SDS–polyacrylamide gel electrophoresis, we have been able to show that major changes in gene transcription occur during sporulation. Following an overall reduction in the abundance of many mRNAs, several genes identified as the result of an increase in the abundance of their transcripts, are highly expressed during the latter stages of sporulation. A study of two genes whose transcription is down-regulated has provided evidence which shows that both single copy and repetitive sequences are regulated during sporulation of the oocyst.