Lifespan & Lethality models

In lifespan assays, healthy worms at the L4 larval stage are exposed to a toxic agent, for example 24 h and then placing them on NGM plates with E. coli OP50. To prevent the production of offspring, 5-fluorodeoxyuridine is added. Worms are transferred to new plates every 3 days. The number of survivors is recorded daily until all animals die. The survival rate is calculated by dividing the number of live nematodes by the total number of nematodes, including both live and dead worms. The lifespan is defined as the time period between the L4 larval stage and death.

 

Lethality assay is performed to determine the death rate derived from acute toxicity in a concentration-response curve basis. 10 ± 1 young adults are transferred in microplates which contain different concentrations of the toxicant and a negative control.
The exposure is carried out at 20 °C during 24 h in the absence of food. Then, the number of live and dead worms is counted through visual inspection using a dissecting microscope. Death is assumed when there is no movement during an observation period of 30 s.