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: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: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: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: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:Transposable elements (TEs) can damage genomes, thus organisms employ a variety of mechanisms to repress TE expression. The PIWI-piRNA pathway is a small RNA pathway that represses TE expression in the germline of animals. Here we explore the function of the pathway in the somatic stem cells of Hydra, a long-lived freshwater cnidarian. Hydra have three stem cell populations, all of which express PIWI proteins; endodermal and ectodermal epithelial stem cells are somatic, whereas the interstitial stem cells have germline competence. To study somatic function of the pathway we isolated piRNAs from Hydra that lack the interstitial lineage and found that these somatic piRNAs map predominantly to TE transcripts and display the conserved sequence signatures typical of germline piRNAs. Three lines of evidence suggest that the PIWI-piRNA pathway represses TEs in Hydra epithelial stem cells. First, epithelial knockdown of the Hydra piwi gene hywi resulted in upregulation of TE expression. Second, degradome sequencing revealed evidence of PIWI-mediated cleavage of TE RNAs in epithelial cells using the ping-pong mechanism. Finally, we demonstrated a direct association between Hywi protein and TE transcripts in epithelial cells using RNA immunoprecipitation. Altogether, our data reveal that the PIWI-piRNA pathway represses TE expression in the somatic cell lineages of Hydra, which we propose contributes to the extreme longevity of the organism. Furthermore, our results, in combination with others, suggest that somatic TE repression is an ancestral function of the PIWI-piRNA pathway.
Project description:Biological adhesion (bioadhesion) is referred to attachment of organisms to either biotic or abiotic surfaces. The differentiated ectodermal basal disc cells of the freshwater cnidarian Hydra secrete proteinaceous glue to temporarily attach themselves to surfaces underwater. In this study, we investigate for the first time the protein content of adhesive secretions from the freshwater cnidarian Hydra magnipapillata strain 105. This secretome were analysed using mass spectrometry and resulting MS/MS data were searched against in silico translated H. magnipapillata transcriptome and results from gene expression.