Project description:The earthworm Eisenia fetida is one of the most used species in standardized soil ecotoxicity tests. Endpoints such as survival, growth and reproduction are ecologically relevant but provide little mechanistic insight into the toxicity pathways, especially at the molecular level. To better understand toxicological modes of action and to facilitate the development of molecular biomarkers, we have obtained 30,245 unique EST sequences from E. fetida and have designed a novel microarray with 15,119 60-mer oligonucleotide probes. These probes target the unique non-redundant EST sequences identified in E. fetida. Using this array we have profiled gene expression of E. fetida after exposure to CL-20, a cage cyclic nitramine previously found exhibiting reversible neurotoxicity to worms. Worms were exposed for 6 days to CL-20. Half of the exposed worms were allowed to recover in a clean environment for 7 days. Electrophysiological analysis showed that the conduction velocity of worm medial giant nerve fiber was significantly decreased after 6-d exposure to CL-20, and that giant nerve fiber function was restored at the end of the 7-d recovery period. Total RNA samples isolated from four treatment groups (6 replicates per group), i.e., 6-d control, 6-d exposed, 13-d control and 6-d exposed with 7-d recovery, were analyzed using the new 15K oligo array. Bioinformatics and statistical analyses have identified specific neurological pathways affected by CL-20 and recovery of these pathways after CL-20 removal. These results provide significant insights on the CL-20 toxic mode of action and how earthworms can recover from chemical stressors.
Project description:Determine gene expression in daphnia exposed to biotic and abiotic stressors. Identify in Daphnia pulex unique gene regulatory patterns involved in the regulation of limited phosphorous.
