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Biochem Genet (2009) 47:329343
DOI 10.1007/s10528-009-9234-6
Jian-Er Long Hai-Xuan Chen
Received: 8 January 2008 / Accepted: 25 September 2008 / Published online: 7 March 2009 Springer Science+Business Media, LLC 2009
Abstract MicroRNAs (miRNA) are a class of noncoding RNA molecules that regulate gene expression by an RNA-interfering pathway through cleavage or inhibition of the translation of target mRNA. The 254 cattle miRNA candidates found by homology searching frequently clustered at certain chromosomes, and some are possibly expressed from more than one genomic locus. They were partially veried by cloning from a small cattle RNA library, where 31 distinct miRNAs were identied: 18 previously registered in the database of miRBase, 11 novel and homologous to known mammalian miRNAs, and 2 potentially novel without homology to any known miRNAs. Partial miRNA expression was detected by RT-PCR in cattle tissues, such as brain, liver, lung, and heart; some were expressed in all tissues and others in a specic tissue. Sequence alignments revealed that many had end variants, most of which differed in the 30 end; a small number differed in the 50 end. This indicates that the same miRNA gene can be individually modied in the process of miRNA biogenesis and could have a different role in regulating target gene expression.
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J.-E. Long (&)
Laboratory of Medical Microbiology, Department of Medical Microbiology and Parasitology, Shang Medical College of Fudan University, 138 Yixueyuan Rd, Shanghai 200032, Peoples Republic of Chinae-mail: [email protected]
J.-E. Long H.-X. Chen
Institute of Medical Genetics, Shanghai Jiaotong University, 24/1400 West Beijing Rd, Shanghai 200040, Peoples Republic of China
Identication and Characteristics of Cattle MicroRNAs by Homology Searching and Small RNA Cloning
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330 Biochem Genet (2009) 47:329343
Keywords MicroRNA Cattle Homology searching Small RNA cloning
Introduction
MicroRNAs (miRNAs) are a class of single-stranded RNAs, 1925 nucleotides (nt) in length, that are generated from endogenous hairpin-shaped transcripts. The rst miRNA was discovered in larval mutants of the nematode Caenorhabditis elegans and was identied as a down-regulator of gene expression. Larval worms with mutations in the lin-4 gene showed defects in the timing of cell division, and the miRNA encoded by the lin-4 gene...