No abstract

No abstract

The use of environmental DNA (eDNA) for monitoring aquatic macrofauna allows the non-invasive species determination and measurement of their DNA abundance and typically involves the analysis of eDNA captured from water samples. In this proof-of-concept study, we focused on the novel use of eDNA extracted from archived suspended particulate matter (SPM) for identifying fish species using metabarcoding, which benefits from the prospect of retrospective monitoring and also analysis of fish communities through time. We used archived SPM samples of the German Environmental Specimen Bank (ESB), which were collected using sedimentation traps from different riverine points in Germany. Environmental DNA was extracted from nine SPM samples differing in location, organic content, and porosity (among other factors) using four different methods for the isolation of high-quality DNA. Application of the PowerSoil DNA Isolation Kit with an overnight incubation in lysis buffer, resulted in DNA extraction with the highest purity and eDNA metabarcoding of these eDNA fragments was used to detect a total of 29 fish taxa among the analyzed samples. Here we demonstrated for the first time that SPM is a promising source of eDNA for metabarcoding analysis, which could provide valuable retrospective information (when using archived SPM) for fish monitoring, complementing the currently used approaches. Suspended particulate matter (SPM) is one of the fundamental elements in aquatic ecosystems (in addition to the water phase and the sediment) and, because it can act as a source and transport mechanism for aquatic particles, is useful for assessing the contamination of surface water 1. As such, SPM monitoring is an important consideration under the Water Framework Directive 2000/60/EC (WFD) 2 and is used in European regulatory chemical monitoring programs (e.g. in Germany 3 and Netherlands 4). Among the other quality elements monitored under the WFD is the state of the aquatic macrofauna (e.g. fish communities), which provide a good measure for the biological and chemical status of the water bodies. SPM monitoring for this context is yet to be explored. Traditionally, the response of biotic communities to human-induced stressors are assessed using taxonomic approaches (e.g. electrofishing), but these are typically limited by their scalability, restricted temporal and spatial resolution, invasiveness, and the high level of expertise required to identify the species 5. Moreover, rare taxa (e.g. invasive species-Neogobius melanostomus, or migratory species-Salmo salar, Anguilla anguilla, Alosa alosa) are especially difficult to monitor because they require an intensive survey effort. DNA-based tools can overcome many of the above-mentioned problems and could complement traditional approaches and biomonitoring strategies 6. Recently, the use of environmental DNA (eDNA), which is the trace amounts of DNA discharged by organisms via excretion of urine, feces, body cells, eggs, etc., enables the non-invasive detection of species and their approxima...

To be defined as an endocrine disruptor, a substance has to meet several criteria, including the induction of specific adverse effects, a specific endocrine mode of action, and a plausible link between both. The latter criterion in particular might not always be unequivocally determined, especially because the endocrine system consists of diverse endocrine axes. The axes closely interact with each other, and manipulation of one triggers effects on the other. The present review aimed to identify some of the many interconnections between these axes. The focus was on fish, but data obtained in studies on amphibians and mammals were considered if they assisted in closing data gaps, because most of the endocrine mechanisms are evolutionarily conserved. The review includes data both from ecotoxicological studies and on physiological processes and gives information on hormone/hormone receptor interactions or gene transcription regulation. The key events and key event relationships identified provide explanations for unexpected effects on one axis, exerted by substances suspected to act specifically on another axis. Based on these data, several adverse outcome pathway (AOP) segments are identified, describing connections between the hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-thyroid (HPT) axes, the HPG and hypothalamic-pituitary-adrenal/interrenal (HPA/I) axes, and the HPT and HPA/I axes. Central key events identified across axes were altered aromatase activity as well as altered expression and function of the proteins 11b-hydroxysteroid dehydrogenase (11b-HSD) and steroidogenic acute regulatory (StAR) protein. Substance classes that act on more than one endocrine axis were, for example, goitrogens or aromatase inhibitors. Despite the wealth of information gathered, the present review only provides a few insights into the molecular nets of endocrine axes, demonstrating the complexity of their interconnections.

No abstract