Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Deep sequencing of small RNA facilitates tissue and sex associated microRNA discovery in zebrafish

ABSTRACT: The role of microRNAs in gene regulation has been well established. The extent of miRNA regulation also increases with increasing genome complexity. Though the number of genes appear to be equal between human and zebrafish, substantially less microRNAs have been discovered in zebrafish compared to human (Release 19). It appears that most of the miRNAs in zebrafish are yet to be discovered. We sequenced small RNAs from brain, gut, liver, ovary, testis, eye, heart and embryo of zebrafish. In brain, gut and liver sequencing was done in male and female separately. Majority of the sequenced reads (16-62%) mapped to known miRNAs, with the exception of ovary (5.7%) and testis (7.8%). Using the miRNA discovery tool (miRDeep2), we discovered novel miRNAs from the un-annotated reads that ranged from 7.6 to 23.0%, with exceptions of ovary (51.4%) and testis (55.2%). The prediction tool identified a total of 459 novel pre-miRNAs. We compared expression of miRNAs between different tissues and between males and females to identify tissue associated and sex associated miRNAs respectively. These miRNAs could serve as putative biomarkers for these tissues. The brain and liver had highest number of tissue associated (22) and sex associated (34) miRNAs, respectively. This study comprehensively identifies tissue and sex associated miRNAs in zebrafish. Further, we have discovered 459 novel pre-miRNAs (~30% seed homology to human miRNA) as a genomic resource which can facilitate further investigations to understand miRNA-mRNA gene regulatory networks in zebrafish which will have implications in understanding the function of human homologs. Known miRNA profiling, novel miRNA discovery and identification of tissue associated and sex associated miRNAs from sRNA deep sequencing data of different tissues and embryo of zebrafish (in triplicate) was carried out using the Illumina HiSeq 2000 platform.

ORGANISM(S): Danio rerio

SUBMITTER: Vivek Tanavde

PROVIDER: E-GEOD-57169 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Prenatal exposure to ethanol leads to a myriad of developmental disorders known as fetal alcohol spectrum disorder, often characterized by growth and mental retardation, central nervous system damage and specific craniofacial dysmorphic features. Although the exact mechanisms of ethanol toxicity are not well understood it is known that ethanol exposure during development affects the expression of several genes involved in cell cycle control, apoptosis and transcription. MicroRNAs (miRNAs) are implicated in some of these processes however it is unclear if they are involved in ethanol-induced toxicity. Here we tested whether ethanol deregulates miRNA expression in zebrafish embryos and if a miRNA deregulation signature could be inferred. For this, zebrafish embryos were exposed to two different ethanol concentrations (1% and 1.5%) from 4 hours post-fertilization (hpf) to 24hpf. MicroRNA expression profiles revealed that ethanol exposure induces deregulation of miRNA expression significantly. Seven miRNAs are commonly up-regulated after both ethanol treatments, namely miR-153a, miR-725, miR-30d, let-7k, miR-100, miR-738 and miR-732, whereas downregulation of miR-23a, miR-203, let-7c, miR-128 and miR-193b is detected after 1% ethanol exposure only. Target prediction of deregulated miRNAs shows that putative targets are involved in cell cycle control, apoptosis and transcription, which are the main processes affected by ethanol toxicity. The overall study shows that the effects of ethanol on miRNA deregulation are dose-dependent and that miRNAs are relevant in the context of alcohol toxicity. Moreover, a miRNA toxicity signature for embryonic ethanol exposure was obtained. Zebrafish embryos were obtained from spawning adults in groups of about 10 males and 10 females. Zebrafish embryos were collected and Petri dishes with approximately 250 eggs each were incubated at 28M-BM-:C to allow normal zebrafish development until 4hpf, when blastula is reached. At this stage, embryos were examined under a dissecting microscope and those that had developed normally were selected for EtOH exposure (approximately 200 eggs). Briefly, 200 embryos were randomly distributed into plastic Petri dishes containing 20 mL of EtOH test solutions (1% EtOH, 1.5% EtOH). All solutions were made by dilution of absolute EtOH in system water. Exposure was from 4hpf to 24hpf. At this stage, solutions were changed by system water and embryos were allowed to grow until 24hpf. The control group was allowed to grow in plain system water. Zebrafish embryos were collected at 24hpf for microarray analysis. Two biological replicates were performed for each assay.

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Deep sequencing of small RNA facilitates tissue and sex associated microRNA discovery in zebrafish

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