Transcription of "Lampbrush" chromosomes in a eukaryote
The
visible DNA strand is
being
transcribed by a series of closely-packed RNA polymerase (RNAPol)
molecules moving serially along the strand. Each RNAPol
trails a filament corresponding to an rRNA transcript. Note
that the
direction of transcription is towards the broad end of the lampbrush: the
longest filaments trail from
an RNAPol that
attached
first.
Lampbrush chromosomes are found in the oocytes of an amphibian, the European crested newt (Notopthalmus). Instead of condensing during meiotic prophase, they remained uncoiled so as to allow extensive transcription of rRNA genes to make the large number of ribosomes necessary for early development. In this case, therefore, the RNA transcript is not translated.
Lampbrush chromosomes are found in the oocytes of an amphibian, the European crested newt (Notopthalmus). Instead of condensing during meiotic prophase, they remained uncoiled so as to allow extensive transcription of rRNA genes to make the large number of ribosomes necessary for early development. In this case, therefore, the RNA transcript is not translated.