Intracellular Invasion of Green Algae Inside Salamander Host

Salamander embryosPhoto: Courtesy Roger HangarterSalamander embryos grow inside egg capsules that are covered with and usually infiltrated by a type of green algae

A recent study published in the journal Proceedings of the National Academy of Sciences (PNAS) has uncovered very surprising facts about the relationship between spotted salamander eggs and algae. This is the very first known example of an eukaryotic algae that has been discovered living inside the cells of developing embryos in a spotted salamander.

This is a breakthrough discovery as this is the first time ever that such symbioses have been found in any vertebrate. In an email, Roger Hagarter, the report’s sole American co-author, and a biologist at Indiana University in Bloomington, said: “The association between algae and salamander eggs has been known for about a century. More recent studies of the association showed that it was symbiotic. The algae provide oxygen to the developing embryos while metabolic waste products from the embryos fertilize the algae. A number of salamander and frog species are known to have associations with algae in their eggs; however, it is likely that more algae symbioses exist than we are aware of.”

Spotted salamandersPhoto: Courtesy Roger HangarterSpotted salamanders found throughout eastern North America are the first known vertebrate to have an endosymbiont.

Vertebrates are backboned animals. The association between the spotted salamander eggs and green algae were noted some 100 years ago. But it wasn’t certain until now that the salamander embryos grow more robustly in the presence of the green algae. In fact, this mutually beneficial relationship took many scientists by surprise.

We asked Roger Hangarter about how this study will highlight biodiversity research on common North American species and this is what he replied: “Although many people have seen salamanders, few know much about their natural history. These organisms depend on vernal woodland pools to reproduce but their habitat is threatened.”

He continued: “As humans continue to build in wooded areas, vernal pools are filled in for various reasons such as fear of mosquitoes breeding in the ponds. Each vernal pool that is destroyed may prevent thousands of salamanders and frogs from mating.”

“Our study also serves as a reminder that there is no need to travel to exotic places to find nature. There is a wealth of biodiversity in any locality that hasn’t been paved over,” he added. Endosymbiosis is a special type of symbiosis, requiring one organism to live inside the cells of another.

This research was supported by grants from the National Science Foundation, Tula Foundation (Canada), the Natural Sciences and Engineering Research Council of Canada and the American Association of Anatomists.

My sincere thanks to Roger Hagarter for his answers and permission to use these rare images.

Source: Press Release and interview with Roger Hagarter