Nanotechnology and Tetrahymena
Recent research by a number of scientists, including Dr. Eduardo Orias (http://www.lifesci.ucsb.edu/mcdb/emeriti/orias/) , one of the founding fathers of Tetrahymena biological research, has shown once again how a simple pond organism like Tetrahymena can play a vital role in understanding our changing world.
Orias and his collaborators used Tetrahymena to examine the question of biomagnification (http://toxics.usgs.gov/definitions/biomagnification.html) of nanoparticles (http://en.wikipedia.org/wiki/Nanoparticle) in the food chain. Their work was recently been published in Nature Nanotechnology (http://www.nature.com/nnano/journal/v6/n1/full/nnano.2010.251.html), and is nicely summarized here// (http://www.physorg.com/news/2010-12-scientists-biomagnification-nanomaterials-simple-food.html).
Briefly, these researchers showed that nanoparticles, in this case cadmium selenide quantum dots (http://mrsec.wisc.edu/Edetc/nanolab/CdSe/index.html), can be transferred from prey to predator, illustrating the potential for biomagnification up the food chain (http://en.wikipedia.org/wiki/Food_chain) from bacteria to protozoa. Tetrahymena feeding on bacteria that had previously accumulated CdSe quantum dots, showed cadmium concentrations about 5 times higher than that in the original bacteria, and the nanoparticles remained essentially intact. Although the nanoparticles were toxic to Tetrahymena, the Tetrahymena cells accumulating the quantum dots did not lyse, making the nanoparticles within the Tetrahymena potentially available to any organism subsequently ingesting the contaminated protozoa. In fact, because Tetrahymena poisoned by these quantum dots lose motility, they actually are more likely to be eaten by predators than unaffected cells.
This finding may be fundamental to understanding the relationship of nanotechnology and the environment. This is the first time that biomagnification has been reported for nanomaterials in an aquatic environment, and it involves organisms at the bottom of the food web with the potential transfer of nanomaterials up the food chain. . Quantum dot nanoparticles remain intact after transfer from the bacteria to the Tetrahymena, suggesting the possibility of long term environmental retention similar to that observed with DTT (http://en.wikipedia.org/wiki/DDT#Environmental_impact).
This work clearly demonstrates the need for caution in the dispersal of nanoparticles into the environment. It also demonstrates how basic research on model organisms like Tetrahymena helps protect the environment and safeguard human health. Not bad for a tiny single cell pond dweller!!
Note that we are developing a Biology and Society module that uses nanotechnology as a stepping stone to address several societal issues. Contact us if you would like to test this module in your classroom!!!!