PPT Slide

Transcription of rRNA precursor RNA in amphibian oocyte nucleus

visualized with electron microscopy (Oscar Miller lab). The full length

precursor rRNA is cleaved after transcription into 28S, 18S, and 5S

rRNA’s. The DNA in the amphibian nucleolus (the site of rRNA

transcription) lacks histone proteins and is transcribed at a very high

rate.

non-transcribed

spacer region

rRNA gene

transcription start

transcription stop

non-transcribed

spacer region

There approximately 900 copies of the rRNA gene per diploid

genome of Xenopus laevis, the African Clawed Frog. This is amplified

to ~1800 copies in the developing oocyte nucleus.

Next slide

Back to first slide

View graphic version