Effect of 17 β-estradiol on developing zebrafish embryos
ABSTRACT: Estrogen signaling is important for vertebrate embryonic development. Here we have used zebrafish (Danio rerio) as a vertebrate model to identify estrogen regulated genes during the first 4 days of development. Zebrafish embryos were exposed to 1 µM 17β-estradiol from 3 hours post fertilization to 4 days post fertilization, harvested daily and subjected to RNA extraction for transcriptome analysis using microarrays. Estrogen responsive genes were analyzed with hierarchical clustering followed by gene function and tissue expression analysis. Markedly distinct sets of genes were up and down-regulated by estrogen treatment at different time points. Among these genes, only the well-known estrogenic marker vtg1 was co-regulated at all time points. Despite this, the biological functional categories targeted by estrogen were similar throughout zebrafish development. Estrogen responsive genes were enriched mainly in the liver, pancreas and brain. In conclusion, our data shows that in zebrafish distinct cohorts of E2 responsive genes are expressed in a tissue specific manner at different developmental stages. However, the biological pathways that are affected are conserved. 30 embryos were pooled as one sample and exposed to 1 μM E2 or vehicle (0.1% DMSO) at approximately 3 hours post fertilization (hpf). At different time points, 1 dpf (24 hpf), 2 dpf (48 hpf), 3 dpf (72 hpf) and 4 dpf (104 hpf), embryos were collected for total RNA extractions. Time points 1 and 2 dpf were performed in biological triplicates of independent pools of RNA while time points 3 and 4 dpf were performed in quadruplicates.
Project description:In zebrafish, vitellogenic oocytes can incorporate significant amounts of 17β-estradiol released from nearby granulosa cells according to a first-order kinetics, since the steroid low polarity ensures high permeability and affinity for yolk lipids. Estrogen bioactivity is likely, because the maternal mRNA for the estrogen receptor-β2 (ers2a) is highly expressed in ovulated oocytes. This transcript is available for translation in the embryo until its sharp decline from 4 to 8 hours post-fertilization (hpf), being replaced by low levels of zygotic ers2a mRNA from 24 hpf to hatching at 48 hpf, as determined by qRT-PCR. Estrogen receptors-α and -β1 are only expressed zygotically at low levels from 24 hpf onwards. To test the functional role of maternal ers2a mRNA, 1- or 2-cell embryos were injected with 10.3 ng each of morpholino to knockdown translation (MO2-ers2a) of both maternal and zygotic ers2a transcripts, missplicing morpholino (MO3-ers2a) to block post-transcriptionally the zygotic transcript alone, and a nonspecific morpholino (MO-control) as a control. Treatment with MO2-ers2a caused severe malformations in 63% of 1-5 dpf larvae, as compared to 10-11% in those treated with MO3-ers2a and MO2-control. Defects included body growth delay and curved shape, abnormal brain and splanchnocranium development, enlarged and hemorrhagic pericardial cavity, uninflated swim bladder and rudimentary caudal fin with aberrant circular motion. Affected larvae could survive for only 12-14 days. Co-injection of an anti-p53 MO failed to rescue the MO2-ers2a-phenotypes, eliminating the possibility of off-target effects. Pangenomic microarray analysis revealed that 240 and 219 significantly expressed transcripts were up- and down-regulated, respectively, by maternal Ers2a protein deficiency in 8-hpf MO2-ers2a-embryos. Also at 48 hpf, 162 and 120 presumably zygotic transcripts were up- and down-regulated, respectively, but only 18 were in common with each of the 8-hpf sets. Whole-mount in situ hybridization revealed an intensified expression of the genes six3.1 and emx1 in MO2-ers2a-embryos at 24-48 hpf, as compared to controls. These findings suggest the involvement of maternal ers2a mRNA in the epigenetic programming of zebrafish development. MO2-ers2a morphants were compared with MO-control at 8 hpf and 48 hpf. MO2-ers2a is a morpholinos selected to knockdown translation of ers2a mRNA
Project description:Zebrafish (Danio rerio) gutGFP transgenic embryos [Tg(XlEef1a1:GFP)s854] were collected at 4 time points: 2 days post fertilization (dpf), 3, dpf, 4 dpf, 6 dpf. Embryos were dissociated into single cells and sorted by FACS based on GFP expression. RNA was extracted from the different cell populations (Stratagene), amplified (NuGEN Ovation), and hybridized to Affymetrix Zebrafish GeneChips. Experiment Overall Design: Series of 24 samples: 4 time points, 3 replicates, 2 samples per replicate (GFP+ and GFP-).
Project description:The requirement for primordial germ cells (PGCs) during sexual differentiation is variable among vertebrates. It has been shown that in zebrafish complete loss of PGCs in the embryos causes exclusive male development. Further, transplantation of a single PGC into a germline deficient zebrafish embryos generates male exclusively, suggesting PGC number might be important for the ovarian fate.To explore how PGC number might regulate sexual development in zebrafish, we experimentally manipulated its number by injecting dnd MO into embryos to generate fish containing a spectrum of PGC number. The experiment was designed to compare transcriptomes between the developing trunk regions of wild type and dnd morphants at different developmental stages. The dnd MO was microinjected into one cell stage embryos to generate zebrafish with a range of PGC numbers. Transcriptomes of developing trunk regions of wild type and dnd morphants at 14 dpf and 22 dpf were analyzed.
Project description:Vitamin D receptors (VDR) are abundantly expressed in developing zebrafish as early as 48 hours post-fertilization, and prior to the development of a mineralized skeleton, and mature intestine and kidney. We probed the role of VDR in zebrafish biology by examining changes in expression of RNA by whole transcriptome shotgun sequencing (RNA-seq) in fish treated with picomolar concentrations of the VDR ligand and hormonal form of vitamin D3, 1a,25-dihydroxyvitamin D3 (1a,25(OH)2D3). We observed significant changes in RNAs encoding proteins of fatty acid, amino acid, and xenobiotic metabolism pathways, and RNAs of transcription factors, leptin, peptide hormones, receptor-activator of NFkB ligand (RANKL), and calcitonin-like ligand receptor pathways. Early small, and subsequent massive changes in >10% of expressed cellular RNAs were observed. At day 2 (24h 1a,25(OH)2D3-treatment), only 5 RNAs were differentially expressed (hormone vs. vehicle). On day 4 (72h-treatment), 78 RNAs; on day 6 (120h-treatment) 1040 RNAs; and on day 7 (144h-treatment), 1755 RNAs were differentially expressed in response to 1a,25(OH)2D3. Fewer RNAs (n = 482) were altered in day 7 embryos treated for 24h with 1a,25(OH)2D3 vs. those treated with hormone for 144h. At 7 days, in 1a,25(OH)2D3-treated embryos, pharyngeal cartilage was larger and mineralization was greater. Changes in expression of RNAs for transcription factors, peptide hormones, and RNAs encoding proteins integral to fatty acid, amino acid, leptin, calcitonin-like ligand receptor, RANKL and xenobiotic metabolism pathways, demonstrate heretofore unrecognized mechanisms by which 1a,25(OH)2D3 functions in vivo in developing eukaryotes. Zebrafish embryos were obtained from mating of Segrest wild-type (SWT) parents under controlled barrier conditions, in the Mayo Clinic Zebrafish Core Facility, in Instant Ocean media . Zebrafish embryos (25-30) were placed in 20 mL embryo medium (pH 7.2) containing 1-phenyl-2-thiourea (PTU) (0.003% (w/v) and were maintained at 28-30 oC. At 24 hpf (1 day post fertilization, dpf), 10 microliters of 1a,25(OH)2D3 in ethanol was added to embryos maintained in 20 mL fresh embryo medium with PTU. The final concentration of 1a,25(OH)2D3 was 300 pM. Control zebrafish were treated with 10 microliters ethanol alone (vehicle controls). The medium containing either 300 pM 1a,25(OH)2D3 or vehicle was changed every 24 h . In experiment 1, at 2, 4, 6 and 7 dpf embryos/larvae were removed and immediately frozen at -80 0C for later RNA preparations. 25-30 embryos per set were used for preparation on RNA. At the same times, 7-12 embryos were fixed in 4% paraformaldehyde in 0.75 X Dulbecco’s phosphate buffered saline (DPBS). In experiment 2, 6 dpf larvae were treated with 1a,25(OH)2D3 (300 pM) or vehicle for 24 h. RNA was prepared from three sets of larvae.
Project description:In zebrafish, ovulated oocytes contain both cortisol deposited from the maternal circulation and maternal mRNA for the glucocorticoid receptor (gr mRNA), which is spread as granular structures throughout the central ooplasm. At the 1-cell stage (0.2 hpf), this transcript is relocated by streamers in the blastodisc area and equally partitioned among blastomeres. At 15 hpf, it is replaced by the zygotic transcript. Morpholino knockdown was applied to block translation (grATG1MO or MO2-nr3c1 and grATG2MO or MO3-nr3c1) of both maternal and zygotic gr transcripts, while a missplicing morpholino (grmismMO or MO4-nr3c1) was used to block post-transcriptionally the zygotic transcript alone. MO2-nr3c1 and MO3-nr3c1 (but not MO4-nr3c1) treatment produced craniofacial and caudal malformations in 1-dpf embryos and 5-dpf larvae, which were also affected by pericardial oedema, persistent yolk sac, reduced subintestinal veins, altered neurogenesis and uninflated swim bladder. Such effects were rescued with trout gr2 mRNA. Pangenomic microarray analysis revealed that 114 and 37 highly expressed transcripts were up- and down-regulated, respectively, by maternal GR protein deficiency in 5-hpf embryos. Similar alterations were found at 10 hpf. These effects were confirmed by real-time PCR of 2 up- (casp8, grp1 and igf2a) and 1 down-regulated transcripts (mcm6) evaluated at 4, 8 and 12 hpf. As the contents of transcripts were modified already at 4 hpf, it seems that the lack of GR affects both ways the molecular machinery for the degradation of maternal mRNAs. These results indicate that the maternal gr transcript participates in the maternal programming of zebrafish development. MO2-nr3c1 morphants were compared with MO2-nr3c1-5m morphants at 5 hpf and 10 hpf. MO2-nr3c1 morphants were compared with wild type (WT) at 5 hpf and 10 hpf. MO2-nr3c1 is a morpholino selected to knockdown translation of gr mRNA. MO2-nr3c1-5m is a specific control morpholino.
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:Small RNA high-throughput sequencing technology was used to characterize the miRNAs in F1-zebrafish after 90-day β-diketone antibiotic (DKA) exposure to F0-zebrafish at 6.25 and 12.5 mg/L. The small RNA libraries from 7-dpf F1-zebrafish were constructed. In total, 10,117,347, 9,818,830 and 12,049,949 raw reads were acquired, respectively, under the different DKA-exposure treatments (0, 6.25 mg/L and 12.5mg/L) from the three miRNAs libraries by Illumina sequencing. Low-quality reads were removed, which included 5' contaminants, those missing the 3' primer or insert tag, sequences with a poly A tail, and those shorter than 17 nt and longer than 25 nt. As a result, 8,141,146 (representing 312,735 unique sequences; control), 8,687,210 (representing 251,508 unique sequences; 6.25 mg/L), and 10,569,566 (representing 441,938 unique sequences; 12.5 mg/L) valid reads in the 17 to 25 nt size range were isolated for further analysis. The sRNAs from the three libraries were similar, and the unique sRNA reads were mainly distributed in the 20-24 nt range, among which 22 and 23 nt accounted for 41.8% and 20.0% of total unique sRNA reads, respectively. The 22-nt sRNAs were the most abundant, with the length distribution of counts of sequ-seqs and unique miRNAs displaying a normal distribution. Sample 1: Examination of small RNA in 7-dpf F1-zebrafish after 90-day DKA exposure to F0-zebrafish at 0 mg/L; Sample 2: Examination of small RNA in 7-dpf F1-zebrafish after 90-day DKA exposure to F0-zebrafish at 6.25 mg/L; Sample 3: Examination of small RNA in 7-dpf F1-zebrafish after 90-day DKA exposure to F0-zebrafish at 12.5 mg/L.
Project description:Expression microarray of livers from 4 dpf control zebrafish larvae, larvae treated with azacytidine, and ahcy mutant larvae Comparison of expression from livers obtained from ahcy+/+ treated with vehicle, ahcy+/+ treated with azacytidine, and ahcy-/- treated with vehicle. We treated larvae starting at 2 dpf with 1 mM azacytidine or vehicle control. Livers were removed at 4 dpf, RNA isolated, and double amplified.
Project description:Exposure experiments with the non-aromatizable fish androgen, 11-ketotestosterone in the range of 0.05-5000 nM were conducted in order to identify potential androgen-responsive genes in zebrafish embryos by microarray analysis. Zebrafish embryos were treated from 96 hpf to 120 hpf in a single experiment with three controls (embryonic medium). Microarray studies were performed using a Custom 8x60k Gene Expression Microarrays (Amadid G4102A, based on the ensembl zebrafish genome version 3) from total RNA with low input labelling and hybridization kit (Agilent Technologies) and one-color design according to the manufacturer instructions. Fluorescent intensities of individual microarray spots were extracted using the Agilent Feature Extraction software. Raw microarray data were converted to log2 values and quantile-normalized. For further statistical analysis, fold changes in relation to the mean of the controls were calculated for each treatment. Zebrafish embryos were treated from 96 hpf to 120 hpf in a single experiment with three controls and 11 concentrations of 11-ketotestosterone ranging from 0.05-5000 nM.
Project description:Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. These multi-ring chemicals differentially activate the Aryl Hydrocarbon Receptor (AHR) in a structurally-dependent manner, and induce toxicity via both AHR-dependent and -independent mechanisms. PAH exposure is known to induce developmental malformations in zebrafish embryos, and recent studies have shown cardiac toxicity induced by compounds with low AHR affinity. Unraveling the potentially diverse molecular mechanisms of PAH toxicity is essential for understanding the hazard posed by complex PAH mixtures present in the environment. We analyzed transcriptional responses to PAH exposure in zebrafish embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR) at a concentration that induces developmental malformations by 120 hours post-fertilization (hpf). Whole genome microarray analysis of mRNA expression at 24 and 48 hpf identified genes that were differentially regulated over time and in response to the three PAH structures. PAH body burden was analyzed at these time points using GC-MS, and demonstrated differences in PAH uptake into the embryos. This was important for discerning dose-related differences from those that represented unique molecular mechanisms. While BAA misregulated the smallest number of transcripts, it caused strong induction of cyp1a and other genes known to be downstream of the AHR, which were not induced by the other two PAHs. Analysis of functional roles of misregulated genes and their predicted regulatory transcription factors also distinguished the BAA response from regulatory networks disrupted by DBT and PYR exposure. These results indicate that systems approaches can be used to classify the toxicity of PAHs based on the networks perturbed following exposure and may provide a path for unraveling the toxicity of complex PAH mixtures. Gene expression was measured in zebrafish embryos after exposure to PAHs. Embryos were batch-exposed in groups of 40 to 25 μM BAA, 25 μM DBT, 25 μM PYR or 1% DMSO vehicle control starting at 6 hpf and collected at 24 or 48 hpf. Four independent biological replicates were prepared for each treatment. The reference was a pool of zebrafish embryos exposed to DMSO control until 24 and 48 hpf.