Project description:Silver exposure is toxic to fish due to disturbances of normal gill function. A proposed toxicity mechanism of silver nanoparticles (AgNP) is derived from the release of silver ions, similar to silver nitrate (AgNO3). However, some datasets support the fact that AgNP can have unique toxic effects that are mediated at the gill. To determine if differences between AgNO3 and AgNP toxicities exist, fathead minnows were exposed to 20 nm PVP- or citrate-coated silver nanoparticles (PVP-AgNP; citrate-AgNP) at the nominal concentration of 200 μg/L or AgNO3 at nominal 6 μg/L for 96 hr. This nominal concentration was applied to approximate the dissolved fraction of Ag in the AgNP suspensions. Mucus production in the water was measured. While mucus production was initially significantly increased in the first 4 h of exposure in all silver treatments compared to control, a decrease in mucus production was observed following 24-96 h of exposure. To determine which genes/pathways are driving this shift in mucus production, gills were dissected and microarray analysis was performed. Hierarchal clustering of differentially expressed genes revealed that all samples distinctly clustered by treatment. There were 109 differentially expressed genes shared among all Ag treatments compared to controls. However, there were 185, 423, and 615 differentially expressed genes unique to AgNO3, PVP-AgNP, and citrate-AgNP, relative to control. While functional analysis indicated several common enriched pathways, such as aryl hydrocarbon receptor signaling, this analysis also indicated some unique pathways between nanosilver and AgNO3. Our results show that AgNO3, PVP-AgNP, and citrate-AgNP exposure affected mucus production in fish gills and also lead to common and unique transcriptional changes.
Project description:Gills of teleost fish represent a vital multifunctional organ; however, they are subjected to environmental stressors, causing gill damage. Gill damage is associated with significant losses in the Atlantic salmon aquaculture industry. Gill disorders due to environmental stressors are exacerbated by global environmental changes, especially with open-net pen aquaculture (as farmed fish lack the ability to escape those events). The local and systemic response to gill damage, concurrent with several environmental insults, are not well investigated. We performed field sampling to collect gill and liver tissue after several environmental insults. Using a 44K salmonid microarray platform, we aimed to compare the transcriptomes of pristine and moderately damaged gill tissue. The gill damage-associated biomarker genes and associated qPCR assays arising from this study will be valuable in future research aimed at developing therapeutic diets to improve farmed salmon gill health.
Project description:The salmon gill poxvirus (SGPV) is a large DNA virus that infects gill epithelial cells in Atlantic salmon and is associated with acute high mortality disease outbreaks in aquaculture. The pathological effects of SGPV infection include gill epithelial apoptosis in the acute phase of the disease and hyperplasia of gill epithelial cells in surviving fish, causing damage to the gill respiratory surface. Transcriptome responses to virus were assessed in gills at different stages of disease
