Project description:Congenital malformations are a prevalent cause of infant mortality in the United States and their induction has been linked to a variety of factors, including exposure to teratogens. However, the molecular mechanisms of teratogenicity are not fully understood. MicroRNAs are an important group of small, non-coding RNAs that regulate mRNA expression. MicroRNA roles in early embryonic development are well established, and their disruption during development can cause abnormalities. We hypothesized that developmental exposure to teratogens such as valproic acid alters microRNA expression profiles in developing embryos. Valproic acid is an anticonvulsant and mood-stabilizing drug used to treat epilepsy, bipolar disorder and migraines. To examine the effects of valproic acid on microRNA expression during development, we used zebrafish embryos as a model vertebrate developmental system. Zebrafish embryos were continuously exposed to valproic acid (1 mM) or vehicle control (ethanol) starting from 4 hours post-fertilization (hpf) and sampled at 48 and 96 hpf to determine the miRNA expression profiles prior to and after the onset of developmental defects. At 96 hpf, 95% of the larvae showed skeletal deformities, abnormal swimming behavior, and pericardial effusion. Microarray expression profiling was done using Agilent zebrafish miRNA microarrays. Microarray results revealed changes in miRNA expression at both the time points. Thirteen miRNAs were differentially expressed at 48 hpf and 22 miRNAs were altered at 96 hpf. Among them, six miRNAs (miR-16a, 18c, 122, 132, 457b, and 724) were common to both time points. Bioinformatic target prediction and examination of published literature revealed that these miRNAs target several genes involved in the normal functioning of the central nervous system. These results suggest that the teratogenic effects of valproic acid could involve altered miRNA expression. Small RNA profiles were deteremined in valproic acid exposed zebrafish embryos using Agilent miRNA microarrays

Project description:Although many drugs and environmental chemicals are teratogenic, the mechanisms by which most toxicants disrupt embryonic development are not well understood. microRNAs (miRNAs), single-stranded RNA molecules of ~22 nt that regulate protein expression by inhibiting mRNA translation and promoting mRNA sequestration or degradation, are important regulators of a variety of cellular processes including embryonic development and cellular differentiation. We hypothesized that exposure to xenobiotics can alter miRNA expression and contribute to the mechanisms by which environmental chemicals disrupt embryonic development. To test this hypothesis for one well-known teratogen, we exposed zebrafish embryos to DMSO (0.1%) or TCDD (5 nM) for 1 hr at 30 hours post fertilization (hpf) and measured microRNA expression using several methods at 36 and 60 hpf. TCDD caused strong induction of CYP1A at 36 hpf (62-fold) and 60 hpf (135-fold) as determined by qPCR, verifying the effectiveness of the exposure. microRNA expression profiles were determined using microarrays (Agilent and Exiqon), next-generation sequencing (SOLiD) and real time RT-PCR. The two microarray platforms yielded results that were similar but not identical; both showed significant changes in expression of miR-451, 23a, 23b, 24 and 27e at 60 hpf. Multiple analyses were performed on the SOLiD sequences yielding a total of 16 miRNAs as potentially differentially expressed by TCDD in zebrafish embryos. However, miR-27e was the only miRNA to be identified as differentially expressed by all three methods (both microarrays, SOLiD sequencing, and qPCR). These results suggest that TCDD exposure causes modest changes in expression of microRNAs, including some (miR-451, 23a, 23b, 24 and 27e) that are critical for hematopoiesis and cardiovascular development. MicroRNA profiling was performed (N=3 biological replicates per group) using custom designed Agilent miRNA microarrays (8x15K) and exiqon miRCURY LNA microarrays. Custom-made Agilent oligonucleotide miRNA microarrays were designed based on zebrafish mature miRNA sequences from miRbase v.16. Each individual array contained a total of 548 unique probes representing 259 mature miRNAs from zebrafish (245), Fugu rubripes (11) and Tetraodon nigriviridis (3). Exiqon miRNA probes were based on zebrafish miRNA sequences from miRbase v. 12.

Project description:Purpose: This study aimed to identify differentially expressed genes and transcripts in zebrafish embryos and larvae following benzo[a]pyrene (BaP) exposure. Methods: Adult zebrafish (2 males × 4 females, N=6 replicate tanks for each treatment) were acclimated for 7 days in an 818 Low Temp Illuminated Incubator (Precision Scientific, Chennai, India) at 28.5°C. Next, adult fish were waterborne exposed to control or 50 μg/L (ppb) BaP for 7 days; ethanol was used as vehicle solvent, and final ethanol concentration was 0.1 mL/L (100 ppm) in all treatment groups. This dose of ethanol is not teratogenic to zebrafish. Water was changed and/or re-dosed daily. From day 7 to 11 of the parental exposure, eggs were collected, counted, and raised in normal conditions (control) or continuously exposed to 50 μg/L BaP until 3.3 and 96 hours post fertilization (hpf). At 3.3 or 96 hpf, embryos (200/pool) or larvae (10/pool) were collected and pooled. Total RNA was isolated for transcriptomic RNA sequencing with Illumina HiSeq2000 (2X100bp). RNA-seq reads were uploaded to the galaxy platform https://main.g2.bx.psu.edu/. RNA-seq reads were trimmed, filtered, and aligned to the zebrafish genome (Danio_rerio.Zv9.68) with the Tophat for Illumina tool. Counting and annotation of RNA-seq reads were performed with Partek Genomics Suite version 6.11. Refseq Transcripts (2013-04-10) and Ensembl Transcripts release 70 databases were used for gene and transcript annotation. Differential expression of gene and transcript reads between treatments was analyzed with R package EdgeR. Genes/transcripts with false discovery rate (FDR) less than 0.05 and absolute fold change greater than 1.5 were considered as significant. Differentially expressed genes were defined as genes with altered expression at either gene or transcript level. Results: Differential expression analysis with EdgeR revealed that gene expression was vastly different between 3.3 hpf zebrafish embryos and 96 hpf larvae. Using Refseq annotation, we found that 10644 out of 13950 transcribed zebrafish genes were differentially expressed between the two developmental time-points, with 5961 up-regulated genes and 4683 down-regulated genes in 96 hpf larvae compared with 3.3 hpf embryos. Similarly, using Ensembl annotation, 16529 out of 19886 transcribed zebrafish genes were differentially expressed, with 9318 up-regulated genes and 7211 down-regulated genes in 96 hpf larvae compared with 3.3 hpf embryos. In 3.3 hpf embryos, four genes and seven transcripts were differentially expressed after BaP exposure. In 96 hpf larvae, 447 and 484 zebrafish genes were significantly up- and down-regulated, respectively, by BaP exposure. Conclusions: Parental and developmental BaP exposure caused gene expression changes in zebrafish embryos and larvae.

Project description:Purpose: This study aimed to identify differentially expressed genes and transcripts in zebrafish embryos and larvae following benzo[a]pyrene (BaP) exposure. Methods: Adult zebrafish (2 males × 4 females, N=6 replicate tanks for each treatment) were acclimated for 7 days in an 818 Low Temp Illuminated Incubator (Precision Scientific, Chennai, India) at 28.5°C. Next, adult fish were waterborne exposed to control or 50 μg/L (ppb) BaP for 7 days; ethanol was used as vehicle solvent, and final ethanol concentration was 0.1 mL/L (100 ppm) in all treatment groups. This dose of ethanol is not teratogenic to zebrafish. Water was changed and/or re-dosed daily. From day 7 to 11 of the parental exposure, eggs were collected, counted, and raised in normal conditions (control) or continuously exposed to 50 μg/L BaP until 3.3 and 96 hours post fertilization (hpf). At 3.3 or 96 hpf, embryos (200/pool) or larvae (10/pool) were collected and pooled. Total RNA was isolated for transcriptomic RNA sequencing with Illumina HiSeq2000 (2X100bp). RNA-seq reads were uploaded to the galaxy platform https://main.g2.bx.psu.edu/. RNA-seq reads were trimmed, filtered, and aligned to the zebrafish genome (Danio_rerio.Zv9.68) with the Tophat for Illumina tool. Counting and annotation of RNA-seq reads were performed with Partek Genomics Suite version 6.11. Refseq Transcripts (2013-04-10) and Ensembl Transcripts release 70 databases were used for gene and transcript annotation. Differential expression of gene and transcript reads between treatments was analyzed with R package EdgeR. Genes/transcripts with false discovery rate (FDR) less than 0.05 and absolute fold change greater than 1.5 were considered as significant. Differentially expressed genes were defined as genes with altered expression at either gene or transcript level. Results: Differential expression analysis with EdgeR revealed that gene expression was vastly different between 3.3 hpf zebrafish embryos and 96 hpf larvae. Using Refseq annotation, we found that 10644 out of 13950 transcribed zebrafish genes were differentially expressed between the two developmental time-points, with 5961 up-regulated genes and 4683 down-regulated genes in 96 hpf larvae compared with 3.3 hpf embryos. Similarly, using Ensembl annotation, 16529 out of 19886 transcribed zebrafish genes were differentially expressed, with 9318 up-regulated genes and 7211 down-regulated genes in 96 hpf larvae compared with 3.3 hpf embryos. In 3.3 hpf embryos, four genes and seven transcripts were differentially expressed after BaP exposure. In 96 hpf larvae, 447 and 484 zebrafish genes were significantly up- and down-regulated, respectively, by BaP exposure. Conclusions: Parental and developmental BaP exposure caused gene expression changes in zebrafish embryos and larvae. Illumina HiSeq2000 deep sequencing was used to generate transcriptomic profiles for BaP-exposed 3.3 hpf zebrafish embryos (n=3 for control, n=3 for BaP) and 96 hpf larvae (n=2 for control, n=2 for BaP).

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Developmental exposure to valproic acid alters the expression of microRNAs involved in neurodevelopment in zebrafish

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