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Micro RNAs are short ( 18-24 nt ) ribonucleic acid molecules performing regulatory functions at the posttranscriptional level . Micro RNAs are involved in the regulation of key developmental processes in eukaryotes . The maturation process of the micro RNAs in plants involves several proteins: DCL1 , HYL1 , Serrat , HEN1 , DDL , HASTY . Biogenesis micro RNA molecules in plants and animals differ in detail. Very little is known about the nucleotide sequences of micro RNA precursors and on the structure of the genes encoding a micro RNA molecules in plants. To date, the exact structure was characterized only 31 of the 190 genes in Arabidopsis thaliana MIR . MIR genes in plants are usually independent transcription units , are very long (as 3108 bp ), and often contain introns. In plants are also known MIR polycistronic genes as well as genes encoding overlapping micro RNA genes encoding the protein. Plant micro RNA may also be present in the introns of protein coding genes . MIR gene transcripts in A. thaliana show significant heterogeneity complicated construction and are subject to maturation processes : spliced ​​, alternatively spliced ​​, revealed the presence of precursors of alternative polyadenylation sites , and transcription of these genes also can be initiated at more than one location. Transcription and Post transcriptional processing of micro RNA precursors are steps where it comes to regulating the level of mature micro- RNA molecules.

The Editorial Board
Andrzej Łukaszyk - przewodniczący, Zofia Bielańska-Osuchowska, Szczepan Biliński, Mieczysław Chorąży, Aleksander Koj, Włodzimierz Korochoda, Leszek Kuźnicki, Aleksandra Stojałowska, Lech Wojtczak

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