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
is trailing 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 amphibians, in this example 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 amphibians, in this example 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.