ABSTRACT
Many multicellular organisms rely on symbiotic associations for support of metabolic activity, protection, or energy. Understanding the mechanisms involved in controlling such interactions remains a major challenge. In an unbiased approach we identified key players that control the symbiosis between Hydra viridissima and its photosynthetic symbiont Chlorella sp. A99. We discovered significant up-regulation of Hydra genes encoding a phosphate transporter and glutamine synthetase suggesting regulated nutrition supply between host and symbionts. Interestingly, supplementing the medium with glutamine temporarily supports in vitro growth of the otherwise obligate symbiotic Chlorella, indicating loss of autonomy and dependence on the host. Genome sequencing of Chlorella sp. A99 revealed a large number of amino acid transporters and a degenerated nitrate assimilation pathway, presumably as consequence of the adaptation to the host environment. Our observations portray ancient symbiotic interactions as a codependent partnership in which exchange of nutrients appears to be the primary driving force.
Subject(s)
Biological Evolution , Chlorella/metabolism , Hydra/metabolism , Symbiosis , Animals , Chlorella/drug effects , Chlorella/genetics , Conserved Sequence , Darkness , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Gene Expression Regulation , Genome , Hydra/drug effects , Hydra/genetics , Hydra/growth & development , Molecular Sequence Annotation , Nitrates/metabolism , Nitrogen/metabolism , Photosynthesis/genetics , RNA, Ribosomal, 18S/genetics , RNA, Ribosomal, 18S/metabolism , Species Specificity , Sugars/pharmacology , Symbiosis/drug effects , Symbiosis/geneticsABSTRACT
The review highlights the dual role that the conserved master regulator FoxO has in aging by coordinating both stem cell proliferation and antimicrobial peptides, effector molecules of the innate immune system. As observed in non-senescent Hydra, continuously high activity of the transcription factor FoxO contributes to continuous stem cell proliferation and could support robust colonization of epithelia with a stable microbiome. The integration of research from stem cell biology, microbiology and ecology into aging concepts (Eco-Aging) acknowledges the multi-organismic nature of all living beings and presents a new conceptual framework for explaining the process of aging.
Subject(s)
Aging , Antimicrobial Cationic Peptides/biosynthesis , Gene Expression Regulation , Hydra/physiology , Stem Cells/physiology , Transcription Factors/metabolism , Animals , Cell Proliferation , Ecosystem , MicrobiotaABSTRACT
Early embryos of many vertebrates and invertebrates develop outside the mother and are exposed to a myriad of potential microbial colonizers. Here we discuss how these embryos are protected from microbial attacks and how they might control and shape their microbiota. In essence we delineate a new role for antimicrobial peptides both in selecting particular bacterial partners during early development and in being important components of a "be prepared" strategy providing transgenerational protection.
