Datensatz

Zusammenfassung

Chemosynthetic symbioses between marine invertebrates and their bacterial symbionts are highly diverse regarding the phylogenetic groups that hosts and symbionts belong to, the habitats they are found in, the metabolic potential of the symbionts and the interactions between host and symbiont. The Lucinidae clam Loripes lucinalis has a sulfur-oxidizing chemoautotrophic symbiont which inhabits bacteriocytes in the gill filaments. L. lucinalis is found in sea-grass associated sediments on Elba, Italy. A so far unresolved question in this species is the way in which the symbionts are taken up by their host, the so-called transmission and colonization modes. Strong indications led to the suggestion that the L. lucinalis takes up the symbionts from the environment throughout its whole life. However this has not been conclusively shown yet. Another question regards the symbionts’ metabolic potential. The lack of genomic data on the symbionts made it difficult to reveal a broad overview of the metabolic pathways the symbionts are capable of. The aims of this study were to visualize the environmental uptake of the symbionts by L. lucinalis and to gain an insight into the symbionts’ metabolic potential with the help of five symbiont draft genomes. In order to visualize the environmental uptake an experiment was conducted where L. lucinalis were exposed to fluorescently labeled symbionts. The appearance of labeled symbionts in the clams' gill tissue was verified by epifluorescence microcopy combined with fluorescence in situ hybridization (FISH). To reveal the symbionts’ metabolic potential the draft genomes were annotated with the tool Rapid Annotation using Subsystem Technology (RAST) and the presence of genes for different metabolic pathways was analyzed. In this study I was able to visualize the environmental uptake of the symbionts by L. lucinalis. Further I was able to gain a broad insight into the symbionts’ metabolic potential and to reveal unexpected properties of the symbionts such as heterotrophy and diazotrophy.