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.
Project description:We designed and constructed a genome-wide microarray with 22,987 70-mer oligonucleotides covering the presently known and predicted genes in the silkworm genome, and surveyed the gene expression in multiple silkworm tissues on day 3 of the fifth instar. Clusters of tissue-prevalent and tissue-specific genes and genes that are differentially expressed in different tissues were identified, and they reflect well major tissue-specific functions on the molecular level. The data presented in this study provide a new resource for annotating the silkworm genome. In the present study, we surveyed gene expression in the A/MSG, the PSG, testis, ovary, fat body, midgut, integument, hemocyte, malpighian tubule, and head from silkworm individuals on day 3 of the fifth instar. In order to establish gene expression differences between sexes, we prepared male and female samples of the same tissue. In addition, we also selectively performed the biological replicates at least twice for five tissues including testis, ovary, A/MSG, PSG and malpighian tubule, to evaluate biological reproducibility. In all, we prepared 30 two-channel hybridizations across the selected tissues for study. We extracted the single channel intensity instead of the ratio value from each two-channel hybridization for further analysis, a strategy that has been reported as being more flexible and valid previously.
Project description: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.
Project description:The molecular mechanism involved in BmNPV resistance was investigated using a genome wide microarray in the midgut tissues of BmNPV infected resistant (Sarupat) and susceptible (CSR-2) Indian silkworm races. In the resistant race, 735 genes were upregulated and 589 genes were down regulated at 12 hours of BmNPV post infection. Similarly in case of susceptible race, 2183 genes were up regulated and 2115 genes were down regulated. Among the differentially expressed genes, nine upregulated and eight down regulated genes were validated using real time qPCR analysis. In Sarupat, the significantly upregulated genes are vacuolar protein sorting associated gene, X fin like protein and Carboxy peptidase E like protein in BmNPV infected midguts, whereas the prominent down regulated genes are glutamate receptor ionotropic kainite 2-like, BTB/POZ domain and transferrin. In the case of CSR-2, the considerably upregulated genes are Peptidoglycan recognition protein S6 precursor and rapamycin while the conspicuous down regulated genes are facilitated trehalose transporter and zinc transporter ZIP1-like gene. Our results provided a vital insights of Bombyx mori in reference with its molecular mechanism in immune response against the BmNPV invasion. Organism : Bombyx mori , Agilent Custom Silkworm Gene Expression 4x44k Array (AMADID: 066047) designed by Genotypic Technology Private Limited.