Dr. Annika Guse
Dr. Annika Guse
Im Neuenheimer Feld 230
Fon +49 6221 54-6264
ed.grebledieh-inu.soc TEA esug.akinna
Coral reefs are the world's most diverse marine ecosystems and their existence depends upon a functional symbiosis between dinoflagellates (genus Symbiodinium) and their coral host. A range of environmental stressors including elevated seawater temperature, acidification, and pollution causes the obligate symbiosis between corals and their intracellular algae to break down. This phenomenon, known as coral “bleaching”, often leads to coral death (Figure 1, left). Our long-term goal is to understand the molecular mechanisms underlying the establishment and maintenance of coral symbiosis.
Figure 1: Healthy corals contain intracellular algae and therefore appear colored. Under environmental stress, the corals loose their symbionts and appear white (bleached) before they ultimately die (A). Similar to corals, symbiotic Aiptasia with intracellular algae appear brown. Aiptasia can be maintained in a bleached (aposymbiotic) but healthy state if fed regularly (B).
To date, progress in this research area has been slow because we lack cellular assays designed to elucidate the molecular details of coral symbiosis, largely because corals are notoriously difficult to work with due to their slow growth, the calcareous skeletons that impede the use of modern molecular and cell biology tools and the fact that most corals reproduce sexually only once a year, significantly limiting the availability of coral larvae for molecular analyses. We use the emerging model system, the marine sea anemone Aiptasia, that has all the advantages of a laboratory model organism and lives – just as reef-building corals - symbiotically with dinoflagellates of the genus Symbiodinium (Figure 1, right).
Specifically, we have established an assay using aposymbiotic Aiptasia adult anemones as well as planula larvae (the stage during which symbiosis establishment naturally occurs) and multiple Symbiodinium strains to establish symbiosis under controlled laboratory conditions. Using this system, we could show that symbiosis specificity is maintained between adults and larval stages. To analyze the molecular machinery and the cellular mechanisms responsible for symbiosis establishment and maintenance, we will use a varity of molecular cell biology tools as well as state-of-the art microscopy.