As is known, C. elegans has a short lifespan of just three to four weeks. It is thought that animal lifespans are influenced by genetic and environmental factors. In the past, Dr. M. Uno and Dr. E. Nishida from Kyoto University had shown that modulation of the insulin signalling pathway (IIS) in C. elegans increased their lifespan by 100 percent, while modulation of TOR pathway lead to a 30 percent increase.
To determine how IIS pathway interacts with the TOR pathway to alter longevity, scientists at the MDI Biological Laboratory, in collaboration with scientists from the Buck Institute for Research on Aging in Novato, Calif., and Nanjing University in China, used a double mutant in which both the IIS and TOR pathways have been genetically modulated.
Logically, the double mutant with modulation of both pathways would be expected to live 130 percent longer. However, as the results is shown, its lifespan was actually prolonged by upwards of 500 percent.
The finding suggest that aging is not simply the result of one specific gene or pathway acting on its own, but rather combinations of genes or pathways interacting with each other, which may explain why no single specific gene that extends longevity in humans has been found.