RNA interference

RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. Historically, it was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling. Only after these apparently unrelated processes were fully understood did it become clear that they all described the RNAi phenomenon. Andrew Fire and Craig C. Mello shared the 2006 Nobel Prize in Physiology or Medicine for their work on RNA interference in the nematode worm Caenorhabditis elegans, which they published in 1998.

Two types of small ribonucleic acid (RNA) molecules – microRNA (miRNA) and small interfering RNA (siRNA) – are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to other specific messenger RNA (mRNA) molecules and either increase or decrease their activity, for example by preventing an mRNA from producing a protein. RNA interference has an important role in defending cells against parasitic nucleotide sequences – viruses and transposons. It also influences development.

RNAI

RNAI is a non-coding RNA that is an antisense repressor of the replication of some E. coli plasmids, including ColE1. Plasmid replication is usually initiated by RNAII, which acts as a primer by binding to its template DNA. The complementary RNAI binds RNAII prohibiting it from its initiation role. The rate of degradation of RNAI is therefore a major factor in control of plasmid replication. This rate of degradation is aided by the pcnB (plasmid copy number B) gene product, which polyadenylates the 3' end of RNAI targeting it for degradation by PNPase.

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Iverni

The Iverni (Ἰούερνοι, Iouernoi) were a people of early Ireland first mentioned in Ptolemy's 2nd century Geography as living in the extreme south-west of the island. He also locates a "city" called Ivernis (Ἰουερνίς, Iouernis) in their territory, and observes that this settlement has the same name as the island as a whole, Ivernia (Ἰουερνία, Iouernia). The name Iverni has been derived from Proto-Indo-European *PiHwerjoHn, "the fertile land". It was probably once the name given to all the peoples of Ireland, but by Ptolemy's time had a more restricted usage applicable to the inhabitants of the south-west. These Iverni can be identified linguistically with the Érainn (Éraind, Érnai, Érna), a people attested in Munster and elsewhere in the early Middle Ages.

The prehistoric Érainn royal dynasties are sometimes referred to as the Dáirine.

Historical septs