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A solar salamander
Photosynthetic algae have been found inside the cells of a vertebrate for the first time.
Anna Petherick
Spotted salamander embryos have an unexpectedly close relationship with a single-celled alga.TED LEVIN/photolibrary.com
Occasionally, researchers stumble across something extraordinary in a system that has been studied for decades.
Ryan Kerney of Dalhousie University in Halifax, Nova Scotia, Canada, did just that while looking closely at a clutch of emerald-green balls — embryos of the spotted salamander (Ambystoma maculatum). He noticed that their bright green colour comes from within the embryos themselves, as well as from the jelly capsule that encases them. …ver más…

"On a lark, I decided to take a long-exposure fluorescent image of a pre-hatchling salamander embryo," says Kerney. When this revealed widely scattered dots of unstained cells fluorescing in the background — an indicator that those cells might contain chlorophyll — Kerney switched to transmission electron microscopy (TEM) to take a closer look.
"The surrounding salamander cells that contain the algae often have several mitochrondria bordering the algal symbiont," Kerney says, pointing to a TEM image.
Mitochondria are the powerhouses of animal cells, converting oxygen and a metabolic product of glucose into ATP, a molecule that cells use to store chemical energy. So salamander mitochondria gathered around an algal cell might be there to take advantage of the oxygen and carbohydrate generated by photosynthesis in that particular cell.
Green flash
How the relationship between the two species originated is unknown. But Kerney is probing how algae enter salamander cells, and some earlier findings are proving helpful.
Lynda Goff, a molecular marine biologist at the University of California, Santa Cruz, worked on this pair of organisms about 30 years ago and demonstrated, among other things, that embryos lacking algae in their surrounding jelly are slow to hatch. "We saw a logarithmic increase in algal cells as the embryo developed," she says. And in those that did contain algae, the community