Project description:The zebrafish is a powerful model for the study of hematopoietic stem and progenitor cells (HSPC). We have developed a novel HSPC-specific transgenic line (Runx1+23:GFP). We have used this line in time-lapse live imaging studies to track the migration of HSPC during development. We have also performed a chemical genetic screen to find small molecules that modulate HSPC numbers during development. Treating embryos from 2-3 days post fertilization (2-3 dpf) then fixing for in situ staining with HSPC probes cmyb and runx1, we found the compound lycorine increased HSPC numbers. Applying this compound during time-lapse live imaging showed increased accumulation of Runx+ HSPC in the caudal hematopoietic tissue (CHT). Treatment from 2-3 dpf, then washing off the compound, had a sustained effect on the size of the HSPC with Runx+ numbers higher at 5 and 7 dpf. We have performed microarray analysis to elucidate the molecular changes within HSPC and endothelial cells after Lycorine treatment. We treated Runx1+23:GFP;kdrl:DsRed2 embryos from 2-3 dpf with 75 uM lycorine in 1% DMSO. We then dissociated the embryos and sorted the Runx+ GFP cells, the kdrl+ DsRed2 cells, and the non-fluorescent negative cells from the total embryo as a comparator population. Total RNA was amplified and biotin labled for hybridization on Affymetrix microarrays. 18 samples were collected and analyzed. There are 3 biological replicates. There are 3 cell type populations: 1) Runx+ HSPC; 2) kdrl+ endothelial cells; 3) non-fluorescent negative cells. There are cell populations from dissociated Lycorine-treated embryo pools, and control DMSO-treated embryo pools.
Project description:The zebrafish is a powerful model for the study of hematopoietic stem and progenitor cells (HSPC). We have developed a novel HSPC-specific transgenic line (Runx1+23:GFP). We have used this line in time-lapse live imaging studies to track the migration of HSPC during development. We have also performed a chemical genetic screen to find small molecules that modulate HSPC numbers during development. Treating embryos from 2-3 days post fertilization (2-3 dpf) then fixing for in situ staining with HSPC probes cmyb and runx1, we found the compound lycorine increased HSPC numbers. Applying this compound during time-lapse live imaging showed increased accumulation of Runx+ HSPC in the caudal hematopoietic tissue (CHT). Treatment from 2-3 dpf, then washing off the compound, had a sustained effect on the size of the HSPC with Runx+ numbers higher at 5 and 7 dpf. We have performed microarray analysis to elucidate the molecular changes within HSPC and endothelial cells after Lycorine treatment. We treated Runx1+23:GFP;kdrl:DsRed2 embryos from 2-3 dpf with 75 uM lycorine in 1% DMSO. We then dissociated the embryos and sorted the Runx+ GFP cells, the kdrl+ DsRed2 cells, and the non-fluorescent negative cells from the total embryo as a comparator population. Total RNA was amplified and biotin labled for hybridization on Affymetrix microarrays.
Project description:In this study, we interrogated the role of DNA methylation in HSPC generation by taking advantage of dnmt1 knockout/knockdown embryos in zebrafish. First, we generated a comprehensive DNA methylation landscape of EHT, which revealed gradually hypermethylated regions associated with vasculogenesis. Taking advantage of dnmt1-deficient embryos, we showed that the decreased DNA methylation blocked HSPC emergence. Mechanistically, we demonstrated that the decreased DNA methylation increased the expression of arterial genes and Notch signaling, thus contributing to defects in the EHT in dnmt1-deficient embryos. Herein, we identified that DNA methylation, as epigenetic regulator, participates in the negative modulation of Notch signaling through inhibiting transcription during HSPC generation in zebrafish.
Project description:Polychlorinated biphenyls (PCBs) are persistent and ubiquitously distributed environmental pollutants. Based on their chemical structure, PCBs are classified into non-ortho substituted and ortho-substituted congeners. Non-ortho-substituted PCBs are structurally similar to dioxin or TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) and their mode of action and toxic effects are well established. In contrast, much less is known about the effects of ortho-substituted PCBs. Studies conducted so far have focused on tissue-specific effects but there is limited knowledge about the effects on the whole organism, particularly the sensitive developmental stages in vertebrates. Hence, in this study we investigated the effects of exposure to an environmentally relevant ortho-substituted PCB (2,2’,4,4’,5,5’-hexachlorobiphenyl; PCB153) on zebrafish embryos. We exposed zebrafish embryos to either DMSO (0.1%; solvent control) or three different concentrations of PCB153 (0.1, 1 and 10 μM) from 4 hours post-fertilization (hpf) to 120 hpf. At the end of the exposure, larvae were sampled for determining transcriptional changes (RNA sequencing) and the remaining embryos were maintained in contaminant-free environment. At 7 and 14 days post-fertilization (dpf), zebrafish larvae were assessed for locomotory behavior. We did not observe any overt phenotypes during the exposure period, but observed a spinal phenotype in the 10μM PCB153 treated group starting at 7 dpf. This phenotype was observed in a dose-dependent manner and majority of the embryos with this phenotype died by 14 dpf. RNA sequencing of 5 dpf larvae exposed to PCB153 also revealed dose-dependent changes in gene expression patterns. A total of 633, 2227, and 3378 differentially expressed genes were observed in 0.1, 1 and 10 μM PCB153 treated embryos, respectively. Among these, 301 genes were common to all treatment groups, and KEGG pathway analysis revealed enrichment of genes related to circadian rhythm, FOXO signaling and insulin resistance pathways. We are currently investigating the functions of genes that are uniquely altered by different PCB153 concentrations. Overall, these results suggest that developmental exposure to PCB153, a PCB congener highly prevalent in the environment, targets multiple physiological processes including photoperiod regulation and metabolism. [Funded by NIH P01ES021923 and NSF OCE-1314642].
Project description:Purpose:To investigate the transcriptomic profiles in zebrafish embryos exposed externally to nucleotides at a critical develpomental window (3-7 days post fertilization) determine biological processes and pathways based on differentially expressed gene transcripts using High Throughput Sequencing (HTS). Methods:Total mRNA profiles of 7 dpf zebraifsh embryos after exposure to 10-5M ATP, AMP, adenosine and adenine were generated by deep sequencing, in triplicate, using Illumina HiSeq2500 Results: There were many differentially expressed genes; including ubiquitin-, actin-, and tubulin-related, showing that the cytoskeleton was altered; other DEGs involved with purine binding, specifically guanine, which was expected as the mixture was composed of purines; DEGs involved with GTP binding were also upregulated, suggesting increased cell signaling,
Project description:Multigenerational effects of arsenic in aquatic organisms remain poorly understood, particularly under environmentally realistic dietary exposure conditions. This study investigated neurobehavioural toxicity in larval offspring of parental Zebrafish treated with arsenic-contaminated natural diet. Adult Zebrafish (F0) were fed with oligochaete blackworms (Lumbriculus variegatus) with arsenic body burdens of <0.05 (Control), 32.42 (Low), and 72.47 (High) µg/g dry weight, respectively, for 60 days. Fish were then bred to generate F1 embryos, which were reared in clean water and diet until 30 days post-fertilization (dpf). In F1 larvae, reactive oxygen species (ROS), apoptosis and lipid peroxidation were evaluated at 5-dpf by fluorescence imaging, and immunostaining was performed at 24 hours post-fertilization (hpf) and 5-dpf to assess neurogenesis and neural signalling pathways. Behavioral assessments included photomotor response (5-dpf), thigmotaxis (15-dpf), social preference (21-dpf), and novel object recognition (30-dpf). Whole-transcriptome analysis in 5-dpf larvae was performed to identify molecular pathways associated with neurobehavioral alterations. Parental dietary arsenic exposure resulted in a dose-dependent increase in ROS production, apoptotic cells, and lipid peroxidation in offspring. Neurodevelopmental impairments were also evident in arsenic lineages, including reduced hypothalamic neurogenesis and impaired development of dopaminergic and motor neurons. Larvae exhibited behavioral abnormalities such as reduced locomotor activity, heightened anxiety, reduced social interaction, and cognitive impairments. Transcriptomic analysis revealed significant dysregulation in pathways related to early neurodevelopment and synaptic functions. These findings demonstrate that environmentally realistic parental arsenic exposure can induce neurobehavioral deficits in offspring by inducing oxidative stress and disrupting neurogenesis and neural signaling pathways.