Found 10066 publications. Showing page 291 of 403:
2016
2015
2006
2016
2015
2023
2012
2011
Maternal effects are thought to be essential tools for females to modulate offspring development. The selective deposition of avian maternal hormones could therefore allow females to strategically adjust the phenotype of their offspring to the environmental situation encountered. However, at the time of egg formation, several contaminants are also transferred to the egg, including per- and polyfluoroalkyl substances (PFAS) which are ubiquitous organic contaminants with endocrine disrupting properties. It is, however, unknown if they can disrupt maternal hormone deposition. In this study we explored relationships between female PFAS burden and maternal deposition in the eggs of steroids (dihydrotestosterone, androstenedione and testosterone), glucocorticoids (corticosterone) and thyroid hormones (triiodothyronine and thyroxine) in a population of the Arctic-breeding black-legged kittiwake (Rissa tridactyla). Egg yolk hormone levels were unrelated to female hormone plasma levels. Second-laid eggs had significantly lower concentrations of androstenedione than first-laid eggs. Triiodothyronine yolk levels were decreasing with increasing egg mass but increasing with increasing females' body condition. Testosterone was the only transferred yolk hormone correlated to maternal PFAS burden: specifically, we found a positive correlation between testosterone in yolks and circulating maternal perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDcA) and perfluoroundecanoic acid (PFUnA) in first-laid eggs. This correlative study provides a first insight into the potential of some long-chain perfluoroalkyl acids to disrupt maternal hormones deposition in eggs and raises the question about the consequences of increased testosterone deposition on the developing embryo.
2023
2011
2012
2008
2008
2008
2024
2013
2005
Remote marine areas of the Arctic have become a sink for pollutants like Persistent Organic Pollutants (POPs), transported long distances from southern latitudes. This presence of contaminants is creating pressure on Arctic organisms. As such, Svalbard´s wildlife has been monitored for decades to follow temporal trends of pollutants, in addition to better understanding the effects of pollutants on Arctic wildlife.
Seabirds are a key group of Arctic animals that are particularly sensitive to the pollutants’ toxicity via effects on behavior, demography and long-term population viability. Understanding how pollutants affect population viability is essential to protect Arctic wildlife but has been an understudied topic in marine ecology.
Two populations of female common eider (Somateria mollissima) have been monitored in Kongsfjorden (Svalbard) and Grindøya (Troms) since 2007 and 1984, respectively. Concentrations of POPs have been analyzed in eiders blood samples, between 2007 and 2009 for Kongsfjorden and from 2005 to 2009 for Grindøya. Previous studies found higher concentrations of HCB (Hexachlorobenzene) for common eiders breeding in Kongsfjorden, while it is the concentrations of PCB (polychlorinated bipheyls) that are the highest for the common eiders breeding in Grindøya. Additionally, the adult survival is higher Kongsfjorden compared to Grindøya common eiders. However, the interaction between those different concentrations of POPs and the adult survival of those two populations have not been studied yet.
Here, we will investigate whether POPs may affect adult survival of female common eiders breeding both in Kongsfjorden and Grindøya. If the POP levels are sufficiently high to induce health effects, we predict that higher concentrations of POPs will negatively affect adult survival.
2025
2010
2010
Do cytotoxicity and cell death cause false positive results in the in vitro comet assay?
The comet assay is used to measure DNA damage induced by chemical and physical agents. High concentrations of test agents may cause cytotoxicity or cell death, which may give rise to false positive results in the comet assay. Systematic studies on genotoxins and cytotoxins (i.e. non-genotoxic poisons) have attempted to establish a threshold of cytotoxicity or cell death by which DNA damage results measured by the comet assay could be regarded as a false positive result. Thresholds of cytotoxicity/cell death range from 20% to 50% in various publications. Curiously, a survey of the latest literature on comet assay results from cell culture studies suggests that one-third of publications did not assess cytotoxicity or cell death. We recommend that it should be mandatory to include results from at least one type of assay on cytotoxicity, cell death or cell proliferation in publications on comet assay results. A combination of cytotoxicity (or cell death) and proliferation (or colony forming efficiency assay) is preferable in actively proliferating cells because it covers more mechanisms of action. Applying a general threshold of cytotoxicity/cell death to all types of agents may not be applicable; however, 25% compared to the concurrent negative control seems to be a good starting value to avoid false positive comet assay results. Further research is needed to establish a threshold value to distinguish between true and potentially false positive genotoxic effects detected by the comet assay.
2022