If you could ever imagine most bizarre symbiosis, probably you wouldn’t imagine such a strange couple as salamander and green algae. While the symbiotic relationships in nature are quite common, it is not a practice to happen between two completely different species. Actually, the relationship between a salamander and green algae is the world’s only known example of a vertebrate cell hosting the cells of an entirely different species.
Since the discovery of this unique relationship, scientists aren’t entirely sure why these two very dissimilar organisms have adopted such an intimate arrangement. Now, thanks to a new study conducted by researchers from the American Museum of Natural History in New York, we have got new insights about this unusual bond.
This association was first described in 1888 by natural scientist Henry Orr. He basically started wondering what is going on that the salamanders allow all these green algae to live inside their egg case. It would be like having a bunch of green algae inside of the womb, which is totally bizarre.
Over the time, scientists started to study it. They found that when the sun is out the algae are producing oxygen inside the egg mass. So, if you try to kill the algae or keep them in the dark, the salamanders will be smaller and they might have a poorer chance of survival post-hatching without the benefit of the extra oxygen.
But what are the benefits of algae? The algae may benefit because of nitrogen that is a waste product for the salamander, but that can be utilized for their cells’ metabolism. The nitrogen-rich environment helps algae to grow. This mutual benefits created a unique long-term relationship.
Since green algae is not limited to the egg cases and it’s also located inside cells of a mature salamander’s body, in order to find out what’s going on there at chemical level scientists mapped the complete library of messenger RNA codes transcribed from the genes of algae growing outside of the eggs and compared it with those growing inside the cells.
They found that algae inside salamander cells are stressed and change the way they make energy. Instead of using light energy to produce food to support the salamander host, the algae in salamander cells struggle to adapt to their new environment. Whether the algae benefits from this cell-within-a-cell interaction remains unclear.
So, why do the algae go to all the trouble of setting up camp in the tissues of salamanders only to get stressed out? The researchers aren’t entirely certain, but they have several theories. One possibility is that the relationship protects the salamander from pathogens. Another possibility is that the green algae benefitting the salamander cells by producing nutrients. Finally, it may be just a part of the green algae’s reproductive cycle.
Regardless of the reason, this discovery is changing our thinking about photo-symbioses. Perhaps more couples like this one may exist in nature. Clearly, we have plenty more secrets to discover.