Amphioxus is an extant species closest to the ancestry of vertebrates. Observation of microRNA （miRNA） distribution of amphioxus would lend some hints for evolutionary research of vertebrates. In this study, using t...Amphioxus is an extant species closest to the ancestry of vertebrates. Observation of microRNA （miRNA） distribution of amphioxus would lend some hints for evolutionary research of vertebrates. In this study, using the publicly available scaffold data of the Florida amphioxus （Branchiostomafloridae） genome, we screened and characterized homologs of miRNAs that had been identified in other species. In total, 68 pieces of such homologs were obtained and classified into 33 families. Most of these miRNAs were distributed as clusters in genome. Inter-species comparison showed that many miRNAs, which had been thought as vertebrate- or mammal-specific before, were also present in amphioxus, while some miRNAs that had been considered as protostome-specific before also existed in amphioxus. Compared with ciona, amphioxus had an apparent miRNA gene expansion, but phylogenetic analysis showed that the duplicated miRNAs or clusters of amphioxus had a higher homology level than those duplicated ones in vertebrates.展开更多
MicroRNAs （miRNAs） are a novel class of small, non-coding endogenous RNAs that play critical regulatory roles in many metabolic activities in eukaryotes. Reports of the identification of miRNAs in Sogatella furcife...MicroRNAs （miRNAs） are a novel class of small, non-coding endogenous RNAs that play critical regulatory roles in many metabolic activities in eukaryotes. Reports of the identification of miRNAs in Sogatella furcifera （white-backed planthopper）, the insect that acts as the only confirmed vector of the southern rice black-streaked dwarf virus （SRBSDV）, are limited. In this study, a total of 382 miRNAs were identified in S. furcifera, including 106 conserved and 276 novel miRNAs, using high-throughput sequencing based on two small RNA libraries from viruliferous and non-viruliferous S. furcifera, and these miRNAs belonged to 52 conserved miRNA families and 58 S. furcifera-specific families, respectively. Comparison with miRNAs from 26 insect species and five other species in miRBase showed that more than half of the conserved miRNA families are highly conserved in Hexapoda, while other miRNAs are only conserved in non- dipterans. Furthermore, 4 117 target genes predicted for the 382 identified miRNAs could be categorized into 45 functional groups annotated by Gene Ontology. Compared with non-viruliferous cells, eight up-regulated miRNAs and four down-regulated miRNAs were identified in cells inoculated with SRBSDV, among which miR-14 and miR-n98a may be involved in the immune response to SRBSDV infection. Analyses of the identified miRNAs will provide insights into the roles of these miRNAs in the regulation and expression of genes involved in the metabolism, development and viral infection of S. furciJbra.展开更多
MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that play important roles in plant and animal development. They are usually processed from larger precursors that can form stem-loop structures. Among 20 miRNA f...MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that play important roles in plant and animal development. They are usually processed from larger precursors that can form stem-loop structures. Among 20 miRNA families that are conserved between Arabidopsis and rice, the rice miR395 gene family was unique because it was organized into compact clusters that could be transcribed as one single transcript. We show here that in fact this family had four clusters of total 24 genes. Three of these clusters were segmental duplications. They contained miR395 genes of both 120 bp and 66 bp long. However, only the latter was repeatedly duplicated. The fourth cluster contained miR395 genes of two different sizes that could be the consequences of intergenic recombination of genes from the first three clusters. On each cluster, both 1-duplication and 2-duplication histories were observed based on the sequence similarity between miR395 genes, some of which were nearly identical suggesting a recent origin. This was supported by a miR395 locus survey among several species of the genus Oryza, where two clusters were only found in species with an AA genome, the genome of the cultivated rice. A comparative study of the genomic organization of Medicago truncatula miR395 gene family showed significant expansion of intergenic spaces indicating that the originally clustered genes were drifting away from each other. The diverse genomic organizations of a conserved microRNA gene family in different plant genomes indicated that this important negative gene regulation system has undergone dramatic tune-ups in plant genomes.展开更多
文摘Amphioxus is an extant species closest to the ancestry of vertebrates. Observation of microRNA （miRNA） distribution of amphioxus would lend some hints for evolutionary research of vertebrates. In this study, using the publicly available scaffold data of the Florida amphioxus （Branchiostomafloridae） genome, we screened and characterized homologs of miRNAs that had been identified in other species. In total, 68 pieces of such homologs were obtained and classified into 33 families. Most of these miRNAs were distributed as clusters in genome. Inter-species comparison showed that many miRNAs, which had been thought as vertebrate- or mammal-specific before, were also present in amphioxus, while some miRNAs that had been considered as protostome-specific before also existed in amphioxus. Compared with ciona, amphioxus had an apparent miRNA gene expansion, but phylogenetic analysis showed that the duplicated miRNAs or clusters of amphioxus had a higher homology level than those duplicated ones in vertebrates.
基金Acknowledgments This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences （Grant XDB 11040400）, the Ministry of Science and Technology of China （Grant 2014CB138405）, the National Natural Science Foundation of China （Grant 31571305） and the National Science and Technology Major Project （2013ZX 10004605-001-002）. The funders played no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
文摘MicroRNAs （miRNAs） are a novel class of small, non-coding endogenous RNAs that play critical regulatory roles in many metabolic activities in eukaryotes. Reports of the identification of miRNAs in Sogatella furcifera （white-backed planthopper）, the insect that acts as the only confirmed vector of the southern rice black-streaked dwarf virus （SRBSDV）, are limited. In this study, a total of 382 miRNAs were identified in S. furcifera, including 106 conserved and 276 novel miRNAs, using high-throughput sequencing based on two small RNA libraries from viruliferous and non-viruliferous S. furcifera, and these miRNAs belonged to 52 conserved miRNA families and 58 S. furcifera-specific families, respectively. Comparison with miRNAs from 26 insect species and five other species in miRBase showed that more than half of the conserved miRNA families are highly conserved in Hexapoda, while other miRNAs are only conserved in non- dipterans. Furthermore, 4 117 target genes predicted for the 382 identified miRNAs could be categorized into 45 functional groups annotated by Gene Ontology. Compared with non-viruliferous cells, eight up-regulated miRNAs and four down-regulated miRNAs were identified in cells inoculated with SRBSDV, among which miR-14 and miR-n98a may be involved in the immune response to SRBSDV infection. Analyses of the identified miRNAs will provide insights into the roles of these miRNAs in the regulation and expression of genes involved in the metabolism, development and viral infection of S. furciJbra.
基金supported in part by a grant from Northern Illinois University Foundation to Long MAONational Institutes of Health(NIH)grant to Mitrick JOHNS and Long MAO(No.44-G1A62164)a grant from the National Natural Science Foundation of China for oversea young scholars to Long MAO(No.30228022).
文摘MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that play important roles in plant and animal development. They are usually processed from larger precursors that can form stem-loop structures. Among 20 miRNA families that are conserved between Arabidopsis and rice, the rice miR395 gene family was unique because it was organized into compact clusters that could be transcribed as one single transcript. We show here that in fact this family had four clusters of total 24 genes. Three of these clusters were segmental duplications. They contained miR395 genes of both 120 bp and 66 bp long. However, only the latter was repeatedly duplicated. The fourth cluster contained miR395 genes of two different sizes that could be the consequences of intergenic recombination of genes from the first three clusters. On each cluster, both 1-duplication and 2-duplication histories were observed based on the sequence similarity between miR395 genes, some of which were nearly identical suggesting a recent origin. This was supported by a miR395 locus survey among several species of the genus Oryza, where two clusters were only found in species with an AA genome, the genome of the cultivated rice. A comparative study of the genomic organization of Medicago truncatula miR395 gene family showed significant expansion of intergenic spaces indicating that the originally clustered genes were drifting away from each other. The diverse genomic organizations of a conserved microRNA gene family in different plant genomes indicated that this important negative gene regulation system has undergone dramatic tune-ups in plant genomes.
