ABSTRACT: The maternal transcriptome of the crustacean Parhyale hawaiensis is inherited asymmetrically to invariant cell lineages of the ectoderm and mesoderm
Project description:The maternal transcriptome of the crustacean Parhyale hawaiensis is inherited asymmetrically to invariant cell lineages of the ectoderm and mesoderm [rest_8cell_embryonic_vs_ectoderm]
Project description:The maternal transcriptome of the crustacean Parhyale hawaiensis is inherited asymmetrically to invariant cell lineages of the ectoderm and mesoderm [rest_8cell_embryonic_vs_mesoderm]
Project description:The maternal transcriptome of the crustacean Parhyale hawaiensis is inherited asymmetrically to invariant cell lineages of the ectoderm and mesoderm [late_vs_early_embryonic]
Project description:The embryo of the crustacean Parhyale hawaiensis has a total, unequal and invariant early cleavage. It specifies cell fates earlier than other arthropods like Drosophila, as individual blastomeres of the 8-cell stage are allocated to the germ layers and the germline. Furthermore, the 8-cell stage is amenable to embryological manipulations. These unique features make Parhyale a suitable system for elucidating germ layer specification in arthropods. Since asymmetric localization of maternally provided RNA is a widespread mechanism to specify early cell fates, we asked whether this is also true for Parhyale. A candidate gene approach did not find RNAs that are asymmetrically distributed at the 8-cell stage. Therefore, we designed a high-density microarray from 9400 recently sequenced ESTs (1) to identify maternally provided RNAs and (2) to find RNAs that are differentially distributed among cells of the 8-cell stage. Maternal-zygotic transition takes place around the 32-cell stage, i.e. after the specification of germ layers. By comparing a pool of RNAs from early embryos without zygotic transcription to zygotic RNAs of the germband, we found that more than 15% of the targets on the array were enriched in the maternal transcript pool. A screen for asymmetrically distributed RNAs at the 8-cell stage revealed 129 transcripts, which were associated with germ-layer-specific GO-terms. Cross-correlation analysis of the microarray experiments indicated that half of the asymmetrically distributed RNAs at the 8-cell stage are degraded before the start of zygotic transcription. Finally, we performed knock-down experiments for two of these genes and observed cell-fate-related defects of embryonic development.
Project description:The embryo of the crustacean Parhyale hawaiensis has a total, unequal and invariant early cleavage. It specifies cell fates earlier than other arthropods like Drosophila, as individual blastomeres of the 8-cell stage are allocated to the germ layers and the germline. Furthermore, the 8-cell stage is amenable to embryological manipulations. These unique features make Parhyale a suitable system for elucidating germ layer specification in arthropods. Since asymmetric localization of maternally provided RNA is a widespread mechanism to specify early cell fates, we asked whether this is also true for Parhyale. A candidate gene approach did not find RNAs that are asymmetrically distributed at the 8-cell stage. Therefore, we designed a high-density microarray from 9400 recently sequenced ESTs (1) to identify maternally provided RNAs and (2) to find RNAs that are differentially distributed among cells of the 8-cell stage. Maternal-zygotic transition takes place around the 32-cell stage, i.e. after the specification of germ layers. By comparing a pool of RNAs from early embryos without zygotic transcription to zygotic RNAs of the germband, we found that more than 15% of the targets on the array were enriched in the maternal transcript pool. A screen for asymmetrically distributed RNAs at the 8-cell stage revealed 129 transcripts, which were associated with germ-layer-specific GO-terms. Cross-correlation analysis of the microarray experiments indicated that half of the asymmetrically distributed RNAs at the 8-cell stage are degraded before the start of zygotic transcription. Finally, we performed knock-down experiments for two of these genes and observed cell-fate-related defects of embryonic development.
Project description:The embryo of the crustacean Parhyale hawaiensis has a total, unequal and invariant early cleavage. It specifies cell fates earlier than other arthropods like Drosophila, as individual blastomeres of the 8-cell stage are allocated to the germ layers and the germline. Furthermore, the 8-cell stage is amenable to embryological manipulations. These unique features make Parhyale a suitable system for elucidating germ layer specification in arthropods. Since asymmetric localization of maternally provided RNA is a widespread mechanism to specify early cell fates, we asked whether this is also true for Parhyale. A candidate gene approach did not find RNAs that are asymmetrically distributed at the 8-cell stage. Therefore, we designed a high-density microarray from 9400 recently sequenced ESTs (1) to identify maternally provided RNAs and (2) to find RNAs that are differentially distributed among cells of the 8-cell stage. Maternal-zygotic transition takes place around the 32-cell stage, i.e. after the specification of germ layers. By comparing a pool of RNAs from early embryos without zygotic transcription to zygotic RNAs of the germband, we found that more than 15% of the targets on the array were enriched in the maternal transcript pool. A screen for asymmetrically distributed RNAs at the 8-cell stage revealed 129 transcripts, which were associated with germ-layer-specific GO-terms. Cross-correlation analysis of the microarray experiments indicated that half of the asymmetrically distributed RNAs at the 8-cell stage are degraded before the start of zygotic transcription. Finally, we performed knock-down experiments for two of these genes and observed cell-fate-related defects of embryonic development.
Project description:Here, we present new functional genomic resources for the amphipod crustacean Parhyale hawaiensis, facilitating the exploration of gene regulatory evolution using this emerging research organism. We use Omni-ATAC-Seq, an improved form of the Assay for Transposase-Accessible Chromatin coupled with next-generation sequencing (ATAC-Seq), to identify accessible chromatin genome-wide across a broad time course of Parhyale embryonic development. This time course encompasses many major morphological events, including segmentation, body regionalization, gut morphogenesis, and limb development. In addition, we use short- and long-read RNA-Seq to generate an improved Parhyale genome annotation, enabling deeper classification of identified regulatory elements. We leverage a variety of bioinformatic tools to discover differential accessibility, predict nucleosome positioning, infer transcription factor binding, cluster peaks based on accessibility dynamics, classify biological functions, and correlate gene expression with accessibility.
Project description:We performed RNA-Seq across multiple time points of development (stages 13, 19, 21, 23) in Parhyale hawaiensis and generated an improved genome annotation.