The CU-Boulder researchers attribute the life span variation observed in the genetically identical worms in the study to chance metabolic processes that involve an array of biochemical and kinetic reactions, said Rea.
"This work starts to address the question of why genetically identical organisms raised in identical environments still age at different rates," said Rea. "It suggests that chance alterations in how stress-response mechanisms are maintained dictate how individual organisms respond to specific environmental insults."
Carried out using about 100,000 popular laboratory nematodes known as C. elegans, the study indicated the brightness level triggered by the reporter protein could predict up to a four-fold variation in the life expectancy of a worm. In a typical experiment, the brightest worms had life expectancies of about 16 days, compared to about three days for those with the lowest expressed levels of fluorescent protein. The brightest worms also had the highest tolerance to extended exposure to heat.
"The ability to predict differences in longevity of this magnitude have never before been reported, especially given that the predictions are made on the first day of adult life," Johnson said.
Obtained from jellyfish and widely used in genetic experiments, the green fluorescent protein was attached to a heat-shock protein in the worms called HSP-16. "HSP-16 alone is probably not responsible for observed differences in survival, but instead is likely reflective of a hidden, heterogeneous, but now quantifiable state that dictates the ability of an organism to deal with the rigors of living," the team wrote in Nature Genetics.
An automated "worm sorter" equipped with a laser scanner to swiftly detect fluorescence levels in the nematodes and a pneumatic device that separates them into groups with short pulses of air was used during the study. One of only six suc
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24-Jul-2005