Beneficial symbiotic bacteria encode an exceptional number of toxin-related genes that are all expressed by the symbionts in the host, supporting their key role in host-microbe interactions.

The colonization of corals and their relatives by intracellular microalgae is facilitated by immunity proteins in the animal that contain thrombospondin-type-1 repeats, elucidating the inter-partner recognition processes required for the establishment of this ecologically important symbiosis.

The symbiotic relationship between Hydra and Chlorella is driven by metabolic co-dependence and characterized by changes in the photobiont genome in terms of lack of genes essential in free-living algae.

Morphological and fitness defects imposed on amoebae hosts by Burkholderia symbionts demonstrates symbiont species-specific effects and provides evidence of host adaptation to naturally acquired symbionts.

Coral symbiotic alga is capable of degrading the own cell wall components by cellulase-related enzymes and releasing sugars as a simple and autonomous environmental response, even when the host-derived signals are not present.

Environmental transmission is atypical of symbionts that have undergone genome degradation, yet genetically reduced deep-sea anglerfish symbionts likely persist in the deep sea biome in search of a new host.

Diversification of a conserved cholesterol binder drives functional replacement of cholesterol with symbiont-produced sterols in corals living in nutrient-poor environments.

Physiological differentiation during symbiosis leads to division of labor between smaller and larger cells in an uncultured bacterial tubeworm symbiont population and results in remarkable metabolic diversity and complexity.

The capacity for symbiosis between photosynthetic microalgae and early diverging lineages fungi was demonstrated with microscopy and stable isotope exchange of carbon and nitrogen.

Functional analyses provide evidence for a complex Nod factor signalling where NFRe is necessary for maintaining an optimal symbiotic signalling in the susceptible root zone, and initiation of nodule primordia on the expanding root system.