Project description:Very little is known on the nature of epigenetic states in developing zebrafish despite its growing importance as a model organism in developmental biology. We report histone modifications on promoters of pluripotency genes in zebrafish embryos at the mid-late blastula transition (MBT+) stage. We identify three classes of expressed genes based on these profiles: (1) those with a promoter occupied by marks of active genes without any repressive marks; (2) those co-occupied by both activating and repressive modifications; of these genes, klf4 was notably found to be mosaically expressed in the embryo, possibly accounting for this epigenetic pattern; (3) those occupied by repressive marks with, surprisingly, little not acetylated H3K9 or H4. Culture of embryo-derived cells results in a switch from histone acetylation to K9 and K27 trimethylation on genes transcriptionally inactivated, resulting in a profile similar to that of fibroblasts. All promoters retain H3K4me3, indicating no correlation between H3K4me3 occupancy and gene expression. Our results illustrate a complex chromatin state on the promoter of pluripotency-associated genes in the zebrafish embryo, shortly after the embryonic genome is turned on. We assessed gene expression in unfertilized eggs and the MBT stage of zebrafish embryos (~ 3.5 hpf) using a 44K custom designed chip from Agilent (3 and 4 replicates, respectively). Genes of interest were extracted and evaluated according to expression dynamics and levels.
Project description:This project aimed at identifying developmental stage specific transcript profiles for catecholaminergic neurons in embryos and early larvae of zebrafish (Danio rerio). Catecholaminergic neurons were labeled using transgenic zebrafish strains to drive expression of GFP. At stages 24, 36, 72 and 96 hrs post fertilization, embryos were dissociated and GFP expressing cells sorted by FACS. Isolated RNAs were processed using either polyA selection and libray generation or NanoCAGE. This is the first effort to determine stage specific mRNA profiles of catecholaminergic neurons in zebrafish.
Project description:Humans and animals have problems producing eggs with high embryo developmental competence, but the causes of poor egg quality are usually unknown. This study delivered the first proteomic portraits of egg quality in zebrafish, a leading model for vertebrate development. Egg batches of good and poor quality, evidenced by embryo survival for 24 h, were used to create pooled or replicated sample sets subjected to different levels of fractionation before LC-MS/MS. Obtained spectra were searched against a custom zebrafish proteome database and detected proteins were annotated, categorized and quantified based on their normalized spectral counts. Manual and automated enrichment analyses were highly confirmative, showing that good and poor quality eggs have disparate proteomes. Proteins involved in protein synthesis, energy metabolism, and lipid metabolism, and certain vitellogenin products were strikingly underrepresented in poor quality eggs. Poor quality eggs also had significantly higher representation of proteins related to immune system and endosome/lysosome functioning, oncogenes, and apoptosis, as well as lectins and egg envelope proteins. Quantitative comparisons of highly abundant proteins revealed 9 candidate egg quality markers warranting further study. In conclusion, the zebrafish egg proteome appears to be linked to embryo developmental potential, a phenomenon that begs further investigation.