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MicroRNAs of Bombyx mori identified by Solexa sequencing

ABSTRACT: Background: MicroRNA (miRNA) and other small regulatory RNAs contribute to the modulation of a large number of cellular processes. We sequenced three total RNA libraries prepared from the whole body, and the anterior and posterior silk glands of Bombyx mori, with a view to expanding the repertoire of silkworm miRNAs and exploring transcriptional differences in miRNAs between segments of the silk gland. Results: With the aid of large-scale Solexa sequencing technology, we validated 244 unique miRNA genes, including 191 novel and 53 previously reported genes, corresponding to 309 loci in the silkworm genome. Interestingly, 24 unique miRNAs were widely conserved from invertebrates to vertebrates; 12 unique ones were limited to invertebrates and 33 were confined to insects; whereas the majority of the newly identified miRNAs were silkworm-specific. We identified 21 clusters and 42 paralogs of miRNAs in the silkworm genome. However, sequence tags showed that paralogs or clusters are not prerequisites for coordinated transcription and accumulation. The majority of silkworm-specific miRNAs are located in transposable elements, and display significant differences in abundance between the anterior and posterior silk glands. Conclusions: Conservative analysis revealed that miRNAs serve as phylogenetic markers and function in evolutionary signaling. The newly identified miRNAs greatly enriched the repertoire of insect miRNAs, and provide insights into miRNA evolution, biogenesis, and expression in insects. The differential expression of miRNAs in the anterior and posterior silk glands supports their involvement as new layers in the regulation of the silkworm silk gland.

ORGANISM(S): Bombyx mori

PROVIDER: GSE17965 | GEO | 2010/02/01

SECONDARY ACCESSION(S): PRJNA119935

REPOSITORIES: GEO

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Project description:Background: MicroRNAs (miRNAs) repress target genes at the post-transcriptional level, and function in the development and cell-lineage pathways of host species. Tissue-specific expression of miRNAs is highly relevant to their physiological roles in the corresponding tissues. However, to date, few miRNAs have been spatially identified in the silkworm. Results: We establish for the first time the spatial expression patterns of nearly 100 miRNAs in multiple normal tissues (organs) of Bombyx mori females and males using microarray and Northern-blotting analyses. In total, only 10 miRNAs were universally distributed (including bmo-let-7 and bmo-bantam), while the majority were expressed exclusively or preferentially in specific tissue types (e.g. bmo-miR-275 and bmo-miR-1). We additionally examined the developmental patterns of miRNA expression during metamorphosis of the body wall, silk glands, midgut and fat body. In total, 63 miRNAs displayed significant alterations in abundance in at least 1 tissue during the developmental transition from larvae to pupae (e.g. bmo-miR-263b and bmo-miR-124). Expression patterns of five miRNAs were significantly increased during metamorphosis in all four tissues (e.g. bmo-miR-27 and bmo-miR-305). Conclusions: In this study, we conducted preliminary spatial measurements of several miRNAs in the silkworm. Periods of rapid morphological change were associated with alterations in miRNA expression patterns in the body wall, silk glands, midgut and fat body during metamorphosis. Accordingly, we propose that this ubiquitous or tissue-specific expression of miRNAs supports their critical roles in tissue specification. The results obtained should facilitate future functional analyses. To determine the global spatial expression patterns of miRNAs in silkworm, we designed a DNA oligonucleotide-based microarray examining 92 unique miRNAs with 106 antisense probes. To determine the extent of tissue-specific changes during the specific developmental events, we assessed changes in miRNA expression in four individual tissues and organs (body wall, silk glands, midgut and fat body) from the larval to pupal stages.

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MicroRNAs of Bombyx mori identified by Solexa sequencing

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