Naturally occurring fluorescence has been observed in multiple organisms ranging from bacteria to birds. In macroscopic animals such as birds, fluorescence provides a visual communication signal. However, the functional significance of this phenomenon is unknown in most cases. In a recent study, researchers from the Department of Biochemistry have demonstrated the UV-protective role of fluorescence observed in a tardigrade isolated in the IISc campus.
Tardigrades (also called water bears or moss piglets) are microscopic animals (0.5 to 1 mm in length) with four pairs of legs. They are known for their ability to tolerate extreme physical stresses such as extreme temperature and pressure, ionising radiation, osmotic stress, and even the vacuum of space at low Earth orbit.
In the study, the researchers identified a new species of tardigrade belonging to the genus Paramacrobiotus within the IISc campus. This tardigrade can survive germicidal UV radiation. Suprisingly, these tardigrades use fluorescence as a mechanism to resist lethal ultraviolet radiation ‒ they use a fluorescent shield that absorbs the harmful UV radiation and emits harmless blue light as fluorescence. The team was also able to transfer this UV tolerance property to another tardigrade, Hypsibius exemplaris and to a nematode, Caenorhabditis elegans, which are otherwise sensitive to UV radiation.
Suma HR, Prakash S, Eswarappa SM. Naturally occurring fluorescence protects the eutardigrade Paramacrobiotus sp. from ultraviolet radiation. Biol Lett. 2020 Oct 16(10):20200391. doi: 10.1098/rsbl.2020.0391 (Altmetric score: 488)
This work has been highlighted in
3. National Geographic
4. New Scientist
5. The Guardian