BLOOMINGTON, Ind. -- A species of algae long known to associate with spotted salamanders has been discovered to live inside the cells of developing embryos, say scientists from the U.S. and Canada, who report their findings in this week's Proceedings of the National Academy of Sciences.
This is the first known example of a eukaryotic algae living stably inside the cells of any vertebrate.
"It raises the possibility that more animal/algae symbioses exist that we are not aware of," said Indiana University Bloomington biologist Roger Hangarter, the PNAS report's sole American coauthor. "Since other salamanders and some frog species have similar algae/egg symbioses, it is possible that some of those will also have the type of endosymbioses we have seen in the spotted salamander."
Biologists Ryan Kerney, Eunsoo Kim, Aaron Heiss, and Brian Hall of Dalhousie University in Halifax, Nova Scotia, and Cory Bishop of St. Frances Xavier University in Antigonish, Nova Scotia, are the other members of the research team. Kerney was the report's lead author.
"We were particularly excited to discover this association in spotted salamander embryos, because this species was a model organism for early experimental embryology research and is a locally common salamander in eastern North America," Kerney said. "We hope that this study will highlight biodiversity research on common North American species, which can easily be overlooked or even considered over-studied."
Vertebrates are backboned animals. The group includes amphibians like the spotted salamander, as well as mammals, birds and reptiles. The rarity of vertebrate endosymbiosis, as the cell-within-a-cell association is called, has been thought to be the result of the animals' stringently xenophobic immune systems. Any foreign cell that manages to get as far as breaching a cell membrane normally triggers a number of slay-now-and-ask-questions-later gene systems.
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