Nuclear architecture and genome functioning in plants and animals: what can we learn from both?

In this short review, we combine information about large-scale chromosome and chromatin structure in the interphase nucleus from animals and plants in relation to transcription. We propose a rosette-like structure for interphase chromosomes in higher eukaryotes in which condensed heterochromatin domains act as organizing centers from which euchromatic loops sprout that contain the transcription units available to that particular cell. In the same context, we address the apparent discrepancy between the spatial distribution of transcriptionally active sites in the nucleus and our understanding of the linear organization of genes on the linear genome. It is likely that this paradox can be solved by taking into account the probably large number of genes for nonprotein-coding RNAs.