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:The germ layer concept has been one of the foremost organizing principles in developmental biology, classification, systematics and evolution for 150 years. Of the three germ layers, the mesoderm is found in bilaterian animals but is absent in species in the phyla Cnidaria and Ctenophora, which has been taken as evidence that the mesoderm was the final germ layer to evolve. The origin of the ectoderm and endoderm layers, however, remains unclear with models supporting the antecedence of each as well as a simultaneous origin. We hypothesized that global analysis of gene expression in each layer throughout development may resolve the early events of animal evolution. Here, we determine the temporal and spatial components of gene expression spanning embryonic development for all C. elegans genes and use it to determine the evolutionary age of the germ layers. The gene expression programs of the mesoderm is generally induced after the ectoderm and endoderm germ layers, thus making it the last germ layer to both evolve and develop. Strikingly, the C. elegans endoderm and ectoderm expression programs do not co-induce; rather the endoderm activates earlier. We also observed early expression of endoderm orthologs during the embryology of Xenopus tropicalis, Nematostella vectensis, and the sponge Amphimedon queenslandica. Querying for the phylogenetic ages of specifically expressed genes revealed that the endoderm is comprised of older genes, supporting its antecedence among the germ layers. Taken together, we propose that the endoderm program has retained the feeding functions of the last common ancestor with the choanoflagellates, thus allowing for the specialization of an ectoderm germ layer. Our work reveals that the evolutionary appearance of the germ layers continues to constrain regulatory networks in metazoans. Two temporal assays of C. elegans embryonic development, starting at the zygote: (a) Embryos collected at fixed (~10 minute) time intervals. (b) Embryo segregates, up to five lines of blastomeres, isolated in reference to mitotic events. There were 184 samples in total, representing 100 distnict data points.

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.

			Action	DRS
	82282_97377_FLAVO-2.pep.xml	Pepxml
	82283_97376_FLAVO-1.pep.xml	Pepxml
	82284_97375_OOCYTE-2.pep.xml	Pepxml
	82285_97374_OOCYTE-1.pep.xml	Pepxml
	97374_OOCYTE-1.raw	Raw

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An abundant membrane protein in the NCAM superfamily is required for epithelial organization in sea anemone embryos

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