Figure 3.

Expression of CDK9, cyclin T2 and cyclin K during Xenopus development. (A) Reverse transcription PCR analysis of the developmental expression of CDK9 and its cyclin partners T and K. RNA isolated from embryos at the indicated stages was used as template for reverse transcription followed by PCR amplification of the target genes with specific oligonucleotide primers. CDK9, cyclin T2 and cyclin K are present as maternal transcripts and are expressed throughout early embryonic development. Mix.3 is expressed during late blastula and gastrula stages (boxed). (B) Whole mount in situ hybridization for CDK9, cyclin T and cyclin K during Xenopus development. Expression of CDK9, and its cyclin partners, is detected throughout the embryo at early gastrula stages. Stage 11 embryos were sliced in half (Stage 11 bisected) to reveal the staining pattern inside the embryo. Each of the genes is expressed broadly throughout the mesendoderm during gastrula stages. During gastrulation the expression of CDK9 remains high while the levels of cyclin T2 and, more profoundly, cyclin K decline. At tailbud stage, high levels of expression of CDK9, cyclin T2 and cyclin K are detected in the head with low-level expression detected throughout the body.