Project description:Gene expression was measured using microarrays in 8 hour postfertilization embryos, comparing control versus ethanol-treated (2 to 8 hours postfertilization) embryos. This experiment was performed to determine the gene expression changes that occur in response to ethanol treatment as a model of fetal alcohol spectrum disorder. Fetal alcohol spectrum disorder (FASD) occurs when pregnant mothers consume alcohol, causing embryonic ethanol exposure and characteristic birth defects that include craniofacial, neural and cardiac defects. Gastrulation is a particularly sensitive developmental stage for teratogen exposure, and zebrafish is an outstanding model to study gastrulation and FASD. Epiboly (spreading blastomere cells over the yolk cell), prechordal plate migration and convergence/extension cell movements are sensitive to early ethanol exposure. Here, experiments are presented to characterize mechanisms of ethanol toxicity on epiboly and gastrulation. Epiboly mechanisms include blastomere radial intercalation cell movements and yolk cell microtubule cytoskeleton pulling the embryo to the vegetal pole. Both of these processes were disrupted by ethanol exposure. Ethanol effects on cell migration also indicated that cell adhesion was affected, which was confirmed by cell aggregation assays. E-cadherin cell adhesion molecule expression and distribution, which control epiboly and gastrulation, were not affected. Gene expression microarray analysis was used to identify potential causative factors for early development defects, and expression of the cell adhesion molecule protocadherin-18a (pcdh18a), which controls epiboly, was significantly reduced in ethanol-exposed embryos. Injecting pcdh18a synthetic mRNA in ethanol-treated embryos partially rescued epiboly cell movements, including enveloping layer cell shape changes. Together, data show that epiboly and gastrulation defects induced by ethanol are multifactorial, and include yolk cell (extraembryonic tissue) microtubule cytoskeleton disruption and blastomere adhesion defects, in part caused by reduced pcdh18a expression. Control vs. ethanol-treated zebrafish embryos that were treated from 2 to 8 hours postfertilization. Total RNA from control and ethanol-treated embryos were harvested at 8 hours postfertilization.

Project description:Gene expression was measured using microarrays in 8 hour postfertilization embryos, comparing control versus ethanol-treated (2 to 8 hours postfertilization) embryos. This experiment was performed to determine the gene expression changes that occur in response to ethanol treatment as a model of fetal alcohol spectrum disorder. Fetal alcohol spectrum disorder (FASD) occurs when pregnant mothers consume alcohol, causing embryonic ethanol exposure and characteristic birth defects that include craniofacial, neural and cardiac defects. Gastrulation is a particularly sensitive developmental stage for teratogen exposure, and zebrafish is an outstanding model to study gastrulation and FASD. Epiboly (spreading blastomere cells over the yolk cell), prechordal plate migration and convergence/extension cell movements are sensitive to early ethanol exposure. Here, experiments are presented to characterize mechanisms of ethanol toxicity on epiboly and gastrulation. Epiboly mechanisms include blastomere radial intercalation cell movements and yolk cell microtubule cytoskeleton pulling the embryo to the vegetal pole. Both of these processes were disrupted by ethanol exposure. Ethanol effects on cell migration also indicated that cell adhesion was affected, which was confirmed by cell aggregation assays. E-cadherin cell adhesion molecule expression and distribution, which control epiboly and gastrulation, were not affected. Gene expression microarray analysis was used to identify potential causative factors for early development defects, and expression of the cell adhesion molecule protocadherin-18a (pcdh18a), which controls epiboly, was significantly reduced in ethanol-exposed embryos. Injecting pcdh18a synthetic mRNA in ethanol-treated embryos partially rescued epiboly cell movements, including enveloping layer cell shape changes. Together, data show that epiboly and gastrulation defects induced by ethanol are multifactorial, and include yolk cell (extraembryonic tissue) microtubule cytoskeleton disruption and blastomere adhesion defects, in part caused by reduced pcdh18a expression.

Project description:Eight different types of sample (three samples each) were used in this study of cardiac cell migration in the tunicate Ciona intestinalis. The B7.5 lineage cells were isolated by Fluorescent Activated Cell Sorting (FACS) at the tailbud stage, when the cardiac precursors (anterior B7.5 lineage cells) are migrating into the trunk, while their sister cells (posterior 7.5 lineage cells) remain in the tail, where they form muscle cells. Cells were sorted at the late gastrula stage, prior to migration induction and after manipulation of the FGF-MAPK-Ets signaling pathway (targeted expression of dominant negative FGF receptor and Ets:VP16 fusion protein, targeted expression was achieved using the Mesp cis-regulatory DNA), FoxF function (a direct target of FGF-MAPK-Ets signaling, required primarily for cell migration) by targeted expression of FoxF:VP16 (constitutive activator) or FoxF:WRPW (constitutive repressor, dominant negative), Mesp function (over-expression of Mesp:VP16 inhibits primarily cell migration). Finally, the "whole embryo" samples were collected from dissociated whole tailbud embryos, without FACS. in summary the eight conditions are: "wt (files LC-wt-1,-2,-3)": wild_type B7.5 lineage cells, expressing GFP, sorted at the tailbud stage "Ets:VP16 (files LC-EV-1,-2,-3)": B7.5 lineage cells, expressing GFP and Ets:VP16, sorted at the tailbud stage "DnFGFR (files LC-dnFGFR-1,-2,-3)": B7.5 lineage cells, expressing GFP and dominant-negative FGF receptor, sorted at the tailbud stage. "FoxF:VP16 (files LC-FV-1,-2,-3)": B7.5 lineage cells, expressing GFP and FoxF:VP16, sorted at the tailbud stage. "FoxF:WRPW (files LC-FW-1,-2,-3)": B7.5 lineage cells, expressing GFP and FoxF:WRPW, sorted at the tailbud stage". "Mesp:VP16 (files LC-MV-1,-2,-3)": B7.5 lineage cells, expressing GFP and Mesp:VP16, sorted at the tailbud stage. "Late Gastrula (files LC-LG-1,-2,-3)": wild_type B7.5 lineage cells, expressing GFP, sorted at the late gastrula stage "whole embryo (files LC-whole-1,-2,-3": whole embryos, dissociated at the tailbud stage, not sorted.

Project description:Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a high-production volume organophosphate flame retardant widely used within the United States. Within zebrafish, initiation of TDCIPP exposure at 0.75 h post-fertilization (hpf) results in genome-wide alterations in methylation during cleavage (2 hpf) as well as epiboly delay or arrest (at higher concentrations) during late-blastula and early-gastrula (4-6 hpf). To determine whether these TDCIPP-induced effects were associated with impacts on the transcriptome, embryos were exposed to vehicle (0.1% DMSO) or 2 μM TDCIPP from 0.75 hpf to 6 hpf, and total RNA was extracted from triplicate embryo pools per treatment and hybridized onto duplicate Affymetrix Zebrafish Gene 1.0 ST Arrays per RNA sample. Based on transcriptome-wide profiling, TDCIPP resulted in a significant impact on biological pathways involved in dorsoventral patterning and bone morphogenetic protein (BMP) signaling. Consistent with pathway-level responses, TDCIPP exposure also resulted in strongly dorsalized embryos by 24 hpf – a phenotype that mimicked the effects of dorsomorphin, a potent and selective BMP inhibitor. Moreover, the majority of dorsalized embryos were preceded by epiboly arrest at 6 hpf. Our microarray data also revealed that the expression of sizzled (szl) – a gene encoding a secreted Frizzled-related protein that limits BMP signaling – was significantly decreased by nearly 4-fold at 6 hpf. Therefore, we used a splice-blocking morpholino to test the hypothesis that knockdown of szl phenocopies TDCIPP-induced delays in epiboly progression. Interestingly, contrary to our hypothesis, injection of szl MOs did not affect epiboly progression but, similar to chordin (chd) morphants, resulted in mildly ventralized embryos by 24 hpf. Overall, our findings suggest that TDCIPP-induced epiboly delay may be independent of szl expression and function, and that TDCIPP-induced dorsalization may – similar to dorsomorphin – be due to interference with BMP signaling during early zebrafish.

Project description:The B1 SOX transcription factors SOX1/2/3/19 have been implicated in various processes of early embryogenesis. However, their regulatory functions in stages from the blastula to early neurula remain largely unknown, primarily because loss-of-function studies have not been informative to date. In our present study, we systematically knocked down the B1 sox genes in zebrafish. Only the quadruple knockdown of the four B1 sox genes sox2/3/19a/19b, which are active in the early embryo, resulted in very severe developmental abnormalities, confirming that the B1 sox genes are functionally redundant. We characterized the sox2/3/19a/19b quadruple knockdown embryos in detail by examining the changes in gene expression through microarray analysis as well as in situ hybridization. Importantly, these phenotypic analyses of the quadruple knockdown embryos reveled that the B1 SOX proteins regulate the following distinct processes: (1) early dorsoventral patterning by controlling bmp2b/7; (2) gastrulation movements via the regulation of pcdh18a/18b and non-canonical wnt genes; (3) neural differentiation by regulating the Hes-class bHLH gene her3 and the proneural-class bHLH genes neurog1 (positively) and ascl1a (negatively), and regional transcription factor genes, e.g. hesx1, zic1 and rx3; and (4) neural patterning by regulating signaling pathway genes, cyp26a1 in RA signaling, oep in Nodal signaling, shh, and mdkb. These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo. Microarray analysis was carried out to compare gene expression profiles at the 30% epiboly (30%E), 75% epiboly (75%E) and tailbud (TB) stages between wild-type embryos and the sox2/3/19a/19b quadruple knockdown embryos. RNAs from two independent samples were analyzed for each embryonic stage.

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Mtx2 dependent genes during Zebrafish gastrulation

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