Gene – Environment Interactions / Environmental Genomics
We currently explore the role of FoxO and insulin signaling as key components coordinating a continuously active stem cell population with external signals and metabolic state. The research is aimed to get first insight into the complex networks of gene-environment interactions in an early emerging metazoan using a functional transgenic approach. Recognizing these interactions will provide fundamental and novel insights into toe regulation of stem cell dynamics in response to external signals and metabolic state.
In the absence of an adaptive immune system, Hydra has developed an effective innate immune system to detect and eliminate nonself cells and to survive in a potentially hostile environment. Our work has shown that the innate immune system with its host-specific antimicrobial peptides and rich repertoire of pattern recognition receptors has evolved in response to the need for controlling resident beneficial microbes rather than to defend against invasive pathogens. Yet in spite of all these insights in an ultimately simple “holobiont” we have still not been able to coherently integrate the accumulated abundance of information into a truly mechanistic understanding of host-microbe interactions.
Questions to be addressed in the future include: What are the functional roles of all members of the Hydra holobiont? How do bacteria contribute to the phenotypic stability of their hosts? What effect does a changing environment have on microbial associates and the fitness of the holobiont? Elucidating these issues will not only contribute to the understanding of host interactions with microbial communities in one of the simplest possible animal systems but may also provide conceptual insights into the complexity of host-microbe interactions in general.
A symbiotic view of life
Organisms are shaped by their holobionts and environments. Developmental symbiosis has been found to be universal, and the entire animal, including its persistent symbionts, may be the critical unit of anatomy, physiology, development. This “entire animal” called the holobiont may be a fundamentally important unit of selection. Indeed, not only are we not individuals. We never were. The study of evolution is the study of symbioses. We do not develop as individuals, nor are all our phenotype given to us by our nuclear genes. We develop, function, and mate as teams. “Biology has entered a new era with the capacity to understand that an organism’s genetics and fitness are inclusive of its microbiome” (Brucker and Bordenstein, 2014)
Inter-species interactions between symbiotic algae and Hydra epithelial cells had been the subject of research since decades since they not only provide insights into the basic “tool kit” necessary to establish symbiotic interactions, but are also of relevance in understanding the resulting evolutionary selection processes (e.g. Thorington and Margulis, 1981). The intimacy of the interaction between Hydra and its microbial and algal symbionts, as well as the high evolutionary pressure to maintain a specific symbiont community, indicate that this inter-kingdom association is an important aspect of Hydra biology and evolution. Our current research is focused on exploring the underlying genetics and molecular basis that enables symbiotic Chlorella to survive and proliferate within Hydra cells.