Intracellular invasion of green algae in a salamander host

Ryan Kerney, Eunsoo Kim, Roger P. Hangarter, Aaron A. Heiss, Cory D. Bishop, Brian K. Hall

Research output: Contribution to journalArticlepeer-review

99 Scopus citations


The association between embryos of the spotted salamander (Ambystomamaculatum) and green algae ("Oophilaamblystomatis" Lamber ex Printz) has been considered an ectosymbiotic mutualism. We show here, however, that this symbiosis is more intimate than previously reported. A combination of imaging and algal 18S rDNA amplification reveals algal invasion of embryonic salamander tissues and cells during development. Algal cells are detectable from embryonic and larval Stages 26-44 through chlorophyll auto-fluorescence and algal 18S rDNA amplification. Algal cell ultrastructure indicates both degradation and putative encystment during the process of tissue and cellular invasion. Fewer algal cells were detected in later-stage larvae through FISH, suggesting that the decline in autofluorescent cells is primarily due to algal cell death within the host. However, early embryonic egg capsules also contained encysted algal cells on the inner capsule wall, and algal 18S rDNA was amplified from adult reproductive tracts, consistent with oviductal transmission of algae from one salamander generation to the next. The invasion of algae into salamander host tissues and cells represents a unique association between a vertebrate and a eukaryotic alga, with implications for research into cell-cell recognition, possible exchange of metabolites or DNA, and potential congruence between host and symbiont population structures.

Original languageEnglish
Pages (from-to)6497-6502
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - 19 Apr 2011


  • Amphibian
  • Chlorophyte
  • Endosymbiosis
  • Photosymbiont


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