The establishment of symbiotic systems requires one organism to live in or on a host. For some North American amphibians, these symbionts are algae and they associate with their aquatic egg masses. Researchers have begun to speculate that these smaller organisms initially invade embryonic host tissues and cells and then transfer to the next generation of hosts.
In a previous study, one of the authors of the current study was part of a team that discovered single-celled algae were invading the embryonic cells of their salamander hosts. This was the first report of such an organism in a vertebrate host, and it led the researchers to question why a photosynthetic organism like algae would invade the tissues of an opaque host that will, as yellow spotted salamanders do, spend virtually all of its life underground. They hypothesized that the algae are invading the embryos as part of a system of intergenerational symbiont transfer.
However, it was still very possible, and in fact likely, based upon work done in the 1940s that the algae that invaded egg masses were present in pond water at the time that the egg masses were laid and simply migrated in, thereby becoming acquired environmentally.
The authors of an article published in the current issue of the journal Phycologia
investigate the possibility of environmental symbiont acquisition on
yellow spotted salamanders and their symbionts, a type of single-celled green algae
called Oophila (egg lover) amblystomatis.
Salamander embryos growing inside egg capsules covered with and often infiltrated by Oophila algae. Image Credit: Roger Hangarter.