rRNA genes consist of long tandem repeats clustered on chromosomes, and their products are important functional components of the ribosome. In common wheat (Triticum aestivum), rDNA loci from the A and D genomes were largely lost during the evolutionary process. This biased DNA elimination may be related to asymmetric transcription and epigenetic modifications caused by the polyploid formation....

When cells enter mitosis, RNA synthesis ceases. Yet the RNA polymerase I (pol I) transcription machinery involved in the production of pre-rRNA remains bound to the nucleolus organizing region (NOR), the chromosome site harboring the tandemly repeated rRNA genes. Here we examine whether rDNA transcription units are transiently blocked or "frozen" during mitosis. By using fluorescent in situ hyb...

Few cytogenetic studies have been undertaken using aquatic heteropterans and the nucleolar behavior of these insects has been described in only four species, Limnogonus aduncus, Brachymetra albinerva, Halobatopsis platensis, and Cylindrostethus palmaris. The nucleolus is a cellular structure related to biosynthetic activity and it exhibits a peculiar behavior in the heteropterans of the Triatom...

This paper analyzes the 1-nucleolus and, in particular, its relation to the nucleolus and compromise value. It is seen that the 1-nucleolus of a cooperative game can be characterized using a combination of standard bankruptcy rules for associated bankruptcy problems. In particular, for any zero-normalized balanced game, the 1-nucleolus coincides with the Aumann-Maschler rule (Aumann and Maschle...

In this paper we deal with the problem of extending the concept of nucleolus on fuzzy cooperative games. Described a newly invented definition of nucleolus for fuzzy cooperative games. We prove that the newly defined nucleolus on the set of classical cooperative games coincides with the previously existing one. It is proved that for separate classes of fuzzy games the nucleolus exists and uniqu...

The epithelium of rat small intestine was radioautographed to examine whether RNA is synthesized by the salvage pathway as shown after [3H]uridine injection or by the de novo pathway as shown after [3H]orotic acid injection. The two modes of RNA synthesis were thus investigated during the migration of columnar cells from crypt base to villus top, and the rate of synthesis was assessed by counti...

Are they always about? Not necessarily. They come and go, disappearing in mitosis from late prophase until telophase. During this period, some nucleolar antigens, including RNA polymerase I and topoisomerase I, remain associated with tandemly repeated clusters of ribosomal RNA genes on the condensed chromatin — these chromosomal regions are presumptuously known as nucleolar organising regions (...