Pirna

Also see: Piwi-interacting RNA (piRNA). Pirna is a city in the Free State of Saxony, Germany in the administrative district of the Sächsische Schweiz. The city's population is over 40,000. Pirna is located near Dresden and is an important district town as well as a Große Kreisstadt. It is also known for the gassing of about 15,000 disabled people in Schloss Sonnenstein between June 1940 and August 1941, killings which ceased after pressure was exerted on the authorities by the local population. Today, a small plaque at the base of Sonnenstein Castle remembers the dead.
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Piwi-interacting RNA (piRNA) is a class of small RNA molecules that is expressed uniquely in mammalian testes and forms RNA-protein complexes with Piwi proteins. These piRNA complexes (piRCs) have been linked to transcriptional gene silencing of retrotransposons and other genetic elements in germ line cells, particularly those in spermatogenesis. Purification of these complexes has revealed that these oligonucleotides are approximately 29-30 nucleotides long. They are distinct in size from miRNA and are associated with distinct protein complexes.
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