Project description:Positional RNA-sequencing of isolated Hydra body pieces and RNA-sequencing of fully regenerated Hydra animal was combined with RNA-sequencing of actively regenerating spheroids (see submission E-MTAB-9672) in order to elucidate the role of tissue stretching on regeneration and body pattern formation.
Project description:Hydra has long been studied for its remarkable ability to regenerate its head. Previous studies focusing on molecular mechanisms of axial patterning and head regeneration using a candidate gene approach have revealed a central role for the canonical Wnt pathway. We performed a global gene expression analysis during Hydra magnipapillata head regeneration using RNA-seq to identify additional genes that are transcriptionally regulated during the regeneration of the head organizer in hydra. Differential expression analysis revealed a set of 4,978 genes with significant changes during a 48-hour head regeneration time-course that includes many key genes in the Wnt, TGF-M-NM-2/BMP and MAP kinase pathways. We observed the differential regulation of several genes that are part of the epithelial-to-mesenchymal transition in bilaterians such as Snail. We assembled 806 novel putative lincRNAs with 176 of these are differentially expressed during the time course. We observed the coordinated transcriptional regulation of several factors that regulate the effective pool of free M-NM-2-catenin that together synergize to increase the amount of M-NM-2-catenin available for transcriptional regulation of downstream genes. The differential expression of Snail and some of its interacting regulators and downstream targets suggests that a partial-EMT-like response is involved in hydra head regeneration. This time-course is a valuable resource for the study of the transcriptional dynamics of head regeneration in hydra. mRNA profiling of regenerating head from 6 time points post bisection of Hydra head (H. magnipapillata), generated by deep sequencing, in duplicates, using Illumina HiSeq2500.
Project description:The molecular nature of malignant tumors is well studied in vertebrates, while their evolutionary origin remains unknown. In particular, there is no evidence for naturally occurring malignant tumors in pre-bilaterian animals, such as sponges and cnidarians. This is somewhat surprising given that recent computational studies have predicted that all metazoans are prone to develop tumors. Here we provide first evidence for naturally occurring tumors in Hydra oligactis. Histological, cellular and molecular data reveal that these tumors are transplantable and caused by differentiation arrest of female gametes. Growth of tumor cells is independent from the cellular environment. Tumor bearing polyps have significantly reduced fitness. In addition, Hydra tumors show a greatly altered transcriptome that mimics expression shifts in vertebrate cancers. Therefore, this study shows, that invasive tumors have deep roots in animal phylogeny, and that early branching animals may be informative in revealing the fundamental mechanisms of tumorigenesis. We compared four samples of Hydra oligactis tumor-bearing animals to three samples of female polyps undergoing oogenesis and six samples of female asexual control polyps
Project description:The adult Hydra polyp continuously renews all of its cells using three separate stem cell populations but the genetic pathways enabling these dynamic tissue properties are not well understood. We used Drop-seq to sequence 24,985 Hydra cells and identified the molecular signatures of a broad spectrum of cell states, from stem cells to terminally differentiated cells. We constructed differentiation trajectories for each cell lineage and identified the transcription factors expressed along these trajectories, thus creating a comprehensive map of all developmental lineages in the adult animal. We unexpectedly found that neuron and gland cell differentiation transits through a common progenitor state, suggesting a shared evolutionary history for these secretory cell types. Finally, we have built the first gene expression map of the Hydra nervous system. By producing a comprehensive molecular description of the adult Hydra polyp, we have generated a resource for addressing fundamental questions regarding the evolution of developmental processes and nervous system function.
Project description:Probing the role of mechanical oscillations in Hydra regeneration by manipulating environmental osmotic properties. Single spheroids from a period of 22h were collected at 1h intervals and sequenced in both a normal hypotonic medium (HM), as well an isotonic medium (70mM sucrose).
Project description:Hydra has long been studied for its remarkable ability to regenerate its head. Previous studies focusing on molecular mechanisms of axial patterning and head regeneration using a candidate gene approach have revealed a central role for the canonical Wnt pathway. We performed a global gene expression analysis during Hydra magnipapillata head regeneration using RNA-seq to identify additional genes that are transcriptionally regulated during the regeneration of the head organizer in hydra. Differential expression analysis revealed a set of 4,978 genes with significant changes during a 48-hour head regeneration time-course that includes many key genes in the Wnt, TGF-β/BMP and MAP kinase pathways. We observed the differential regulation of several genes that are part of the epithelial-to-mesenchymal transition in bilaterians such as Snail. We assembled 806 novel putative lincRNAs with 176 of these are differentially expressed during the time course. We observed the coordinated transcriptional regulation of several factors that regulate the effective pool of free β-catenin that together synergize to increase the amount of β-catenin available for transcriptional regulation of downstream genes. The differential expression of Snail and some of its interacting regulators and downstream targets suggests that a partial-EMT-like response is involved in hydra head regeneration. This time-course is a valuable resource for the study of the transcriptional dynamics of head regeneration in hydra.
Project description:Green hydra (Hydra viridissima) harbors endosymbiotic Chlorella and have established a mutual relation. To identify the host hydra genes involved in the specific symbiotic relationship, transcriptomes of intact H. viridissima colonized with symbiotic Chlorella strain A99, aposymbiotic H.viridissima and H. viridissima artificially infected with other symbiotic Chlorella were compared by microarray analysis. The results indicated that genes involved in nutrition supply to Chlorella were upregulated in the symbiotic hydra. In addition, it was induced by supply of photosynthates from the symbiont to the host, suggesting cooperative metabolic interaction between the host and the symbiotic algae.
Project description:The evolution of the first body axis in the animal kingdom and an extensive ability to regenerate makes Hydra, a Cnidarian, an excellent model system to understand the underlying epigenetic mechanisms. We identify that SETD8 is critical for regeneration, and H4K20me1 colocalizes with transcriptional activation machinery locally at the β-catenin bound TCF/LEF binding sites on the promoters of head-associated genes, marking an epigenetic activation node. Contrastingly, a global genome-wide analysis of the H4K20me1 occupancy revealed a negative correlation with transcriptional activation. We propose H4K20me1 as a general repressive histone mark in Cnidaria and describe its dichotomous role in transcriptional regulation in Hydra.