Multivariate evaluation of the effectiveness of delousing treatment efficacy of azamethiphos (Salmosan®) against the salmon louse (Lepeophtheirus salmonis) in Atlantic salmon (Salmo salar) using wellboat, skirt and tarpaulin treatment modalities

Sea lice (Lepeophtheirus salmonis) are the most costly parasitic infestation in the culture of Atlantic salmon (Salmo salar) with control strategies relying heavily on the use of a limited number of chemotherapeutants and traditional univariate analytical tools to evaluate and optimize their delivery. Azamethiphos (Salmosan®) is a powerful delousing agent, which has been administered as a topical treatment using three different modalities: skirt-style enclosures, fully-enclosed tarpaulin enclosures and wellboats. In this study, we analyzed and evaluated the efficacy of azamethiphos treatments between these three modalities against PAAM (pre-adult males and females and, adult males) and adult female (AF) stages using a multivariate approach. The exploratory analysis revealed efficacy in the fully-enclosed tarpaulin modality to be 2.2 times greater compared to skirt-style and wellboat modalities; whereas efficacy against adult females in the wellboat modality was two times larger than in the other modalities. Using the multivariate analysis, treatment efficacy in the fully-enclosed tarpaulin modality was greater than the skirt-style modality, but no significant differences were observed between the wellboat and skirt modalities. These results should be interpreted with caution as differences existed in the abundances and proportions of sea lice stages before treatment that may affect the observed treatment efficacies. For an evaluation and comparison of treatment modalities, multivariate techniques offer added advantages over the more traditional univariate methods, in that simultaneous analysis of multiple sea lice stages and any dependencies or correlation between these stages can be effectively addressed. Statement of relevance: Control of sea lice infestation of Atlantic salmon

Sensitivity of salmon lice (Lepeophtheirus salmonis) in New Brunswick, Canada, to the organophosphate Salmosan® (w/w 50% azamethiphos) using bioassays

Bioassays have been used as a monitoring tool to determine changes in sensitivity of sea lice populations to various bath treatments during the Atlantic salmon production cycle. In this study we report on the results of bioassays conducted between 2009 and 2012 for L. salmonis with the objective of detecting changes in sea lice sensitivity to Salmosan® (w/w 50% azamethiphos), a delousing agent used in the Bay of Fundy region of New Brunswick, Canada. EC50 values ranged from 4.6 ppb to 402 ppb. Although sea lice stage was not a significant factor influencing observed EC50 values, there were significant differences among years, with 2009 being significantly lower than all other years, and 2011 being significantly higher than 2010 or 2012. Season was also found to be a significant predictor with EC50 values in the winter/spring being lower than those predicted in the summer/fall. While sea lice resistance to Salmosan® (w/w 50% azamethiphos) has not been reported from Eastern Canada, variable EC50 values indicate unmeasured influences on tolerance to Salmosan® (w/w 50% azamethiphos) in the populations of L. salmonis sampled from the Bay of Fundy during the 2009 to 2012 period. The possibility of more recent changes in sensitivity remains unknown due to the lack of a centralized repository of bioassay data or other measures that might reflect the emergence of resistant sea lice

MicroRNA Functions in Stress Responses

MicroRNAs (miRNAs) are a class of ~22 nucleotide short noncoding RNAs that play key roles in fundamental cellular processes, including how cells respond to changes in environment or, broadly defined, stresses. Responding to stresses, cells either choose to restore or reprogram their gene expression patterns. This decision is partly mediated by miRNA functions, in particular by modulating the amount of miRNAs, the amount of mRNA targets, or the activity/mode of action of miRNA-protein complexes. In turn, these changes determine the specificity, timing, and concentration of gene products expressed upon stresses. Dysregulation of these processes contributes to chronic diseases, including cancers.National Institutes of Health (U.S.) (RO1-CA133404)National Cancer Institute (U.S.) (PO1-CA42063)National Cancer Institute (U.S.) (Cancer Center Support (core) grant P30-CA14051)Leukemia & Lymphoma Society of America (special fellow