An Example of Automating Nematode Lifespan Studies

The growth of interest in targeting mechanisms of aging has led to the development of a variety of approaches to automating nematode life span studies, some of which are already available as commercial services. Researchers use the nematode species C. elegans in screening studies, searching for compounds that have effects on life span, or that interact with specific aging mechanisms of interest. Running ten thousand compounds through ten thousand dishes of nematode worms is a daunting prospect if it has to be carried out manually, and automation allows a great deal more screening to be accomplished for a given cost.

Despite being an extremely simple animal, C. elegans has differentiated organs such as nerves, skeletal muscles, and a digestive tract, and many mammalian animal-related genes are conserved. It is very useful for cutting-edge research in fields like genetics and molecular biology. However, while lifespan analysis of this nematode provides a great deal of useful information, previous lifespan studies had many limitations including 1) sensitivity to various stimuli at room temperature, 2) a long experimental time required for daily measurements, 3) a lack of objectivity due to a tendency for results to be dependent on experimental technique, and 4) the small number of samples that can be processed at one time making it unsuitable for simultaneous measurement of many samples.

The researchers attempted to resolve these issues by developing a new healthy lifespan assessment system that maintained the advantages provided by nematodes. They focused on determining the optimal conditions in a live cell imaging system for automatically measuring nematode survival, such as counting the number of nematodes in a sample, incubation temperature, medium thickness, feeding conditions, imaging interval, and survival determination method. This became C. elegans Lifespan Auto-monitoring System (C-LAS), a fully automated lifespan measurement system that can non-invasively measure a large number of samples (currently up to 36 samples). C-LAS uses overlapping images of nematodes to identify those that are moving, meaning they are alive, and those that are not moving, meaning they are dead.

The researchers performed a mini-population analysis of nematode healthy lifespan using a combination of C-HAS and statistical analysis on common nematodes with the same genetic background. They found that about 28% of the population had average lifespans, about 30% had long and healthy lifespans, about 35% had healthy lifespans but died prematurely, and about 7% had a long period of frailty. They also found that activating - either genetically - or through administration of the drug metformin - AMP-activated protein kinase (AMPK), which is closely associated with healthy life expectancy, dramatically increased the population with healthy longevity and reduced the population with long periods of frailty. Metformin is thought to increase healthy life expectancy in humans, and the present study supports this idea. Currently, clinical trials are underway to ascertain its association with healthy longevity.



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