Project description:piRNA-deficient Maelstrom (Mael) null mice are characterized by a strong upregulation of LINE-1 (L1) retrotransposon in meiotic spermatocytes. This defect turns out in the accumulation of L1 RNA and ORF1p in their cytoplasm and the formation of prominent ribonucleoprotein aggregates. We used 3-months-old Mael-/- male mice to characterize the RNA present in those ORF1p aggregates. To favor the isolation of complexed versus free ORF1p protein, we first fractionated Mael-/- testis extracts (that we refer to as TOTAL) by sucrose gradient ultracentrifugation, in the presence of EDTA. We then pooled the sucrose fractions where ORF1p macromolecular complexes sediment (fractions 5-8) and used this pool as the INPUT for an anti-ORF1p co-immunoprecipitation (IP) followed by RNA-seq.
Project description:Unveiling the impact of carbon sources on phosphorus release from sediment: Investigation of microbial interactions and metabolic pathways for anaerobic phosphorus recovery
Project description:Aquatic organisms are exposed to many toxic chemicals and interpreting the cause and effect relationships between occurrence and impairment is difficult. Toxicity Identification Evaluation (TIE) provides a systematic approach for identifying responsible toxicants. TIE relies on relatively uninformative and potentially insensitive toxicological endpoints. Gene expression analysis may provide needed sensitivity and specificity aiding in the identification of primary toxicants. The current work aims to determine the added benefit of integrating gene expression endpoints into the TIE process. A cDNA library and a custom microarray were constructed for the marine amphipod Ampelisca abdita. Phase 1 TIEs were conducted using 10% and 40% dilutions of acutely toxic sediment. Gene expression was monitored in survivors and controls. An expression-based classifier was developed and evaluated against control organisms, organisms exposed to low or medium toxicity diluted sediment, and chemically selective manipulations of highly toxic sediment. The expression-based classifier correctly identified organisms exposed to toxic sediment even when little mortality was observed, suggesting enhanced sensitivity of the TIE process. The ability of the expression-based endpoint to correctly identify toxic sediment was lost concomitantly with acute toxicity when organic contaminants were removed. Taken together, this suggests that gene expression enhances the performance of the TIE process. Wild-collected Ampelisca abdita were exposed to either control (from sites in Long Island Sound, labeled LIS) sediment, toxic (from site on Elizabeth River, labeled ER) sediment, a series of mixtures of LIS and ER sediment, sediments manipulated to alter toxin bioavailability, or toxicant amended sediments. Lethality was scored, and survivors were subjected to mRNA expression analysis via oligo microarray.
Project description:Aquatic organisms are exposed to many toxic chemicals and interpreting the cause and effect relationships between occurrence and impairment is difficult. Toxicity Identification Evaluation (TIE) provides a systematic approach for identifying responsible toxicants. TIE relies on relatively uninformative and potentially insensitive toxicological endpoints. Gene expression analysis may provide needed sensitivity and specificity aiding in the identification of primary toxicants. The current work aims to determine the added benefit of integrating gene expression endpoints into the TIE process. A cDNA library and a custom microarray were constructed for the marine amphipod Ampelisca abdita. Phase 1 TIEs were conducted using 10% and 40% dilutions of acutely toxic sediment. Gene expression was monitored in survivors and controls. An expression-based classifier was developed and evaluated against control organisms, organisms exposed to low or medium toxicity diluted sediment, and chemically selective manipulations of highly toxic sediment. The expression-based classifier correctly identified organisms exposed to toxic sediment even when little mortality was observed, suggesting enhanced sensitivity of the TIE process. The ability of the expression-based endpoint to correctly identify toxic sediment was lost concomitantly with acute toxicity when organic contaminants were removed. Taken together, this suggests that gene expression enhances the performance of the TIE process.