Characterization of a Supercluster of SnoRNA Genes from Rice Genome

Small nucleolar RNAs (snoRNAs) are mainly involved in rRNA processing and modification, including the maturation of precursor ribosomal RNAs (pre-rRNA), and methylation and pseudouridy nation of rRNA bases. These moleclules are transcripted independly, along with host gene as an intron or as polycistron, reflecting the different pathways for processing of precursor snoRNAs (pre-snoRNAs) into mature snoRNAs. Analysis ofsnoRNA gene organizations and sequences will enable us to explore their evolutions. Previously, we have briefly mentioned a surprisingly larg cluster from rice, consisting of 5 duplictions of a cluster. It provides a good opportunity to reveal the evolution machanism of the snoRNA genes. Here detailed examination were performed and the processs of snoRNA gene loss, insertion and tranfer and cluster duplication are highlighted.