Absence of system xc⁻ on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x(c)- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration. Methods: Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x(c)-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT(-/-)) mice and irradiated mice reconstituted in xCT(-/-) bone marrow (BM), to their proper wild type (xCT(+/+)) controls. Results: xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT(+/+) mice, xCT(-/-) mice were equally susceptible to EAE, whereas mice transplanted with xCT(-/-) BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected. Conclusions: Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x(c)- on immune cells invading the CNS participates to EAE. Since a total loss of system x(c)- had no net beneficial effects, these results have important implications for targeting system x(c)- for treatment of MS

Effective monitoring of freshwater fish

Freshwater ecosystems constitute only a small fraction of the planet’s water resources, yet support much of its diversity, with freshwater fish accounting for more species than birds, mammals, amphibians, or reptiles. Fresh waters are, however, particularly vulnerable to anthropogenic impacts, including habitat loss, climate and land use change, nutrient enrichment, and biological invasions. This environmental degradation, combined with unprecedented rates of biodiversity change, highlights the importance of robust and replicable programmes to monitor freshwater fish assemblages. Such monitoring programmes can have diverse aims, including confirming the presence of a single species (e.g. early detection of alien species), tracking changes in the abundance of threatened species, or documenting long-term temporal changes in entire communities. Irrespective of their motivation, monitoring programmes are only fit for purpose if they have clearly articulated aims and collect data that can meet those aims. This review, therefore, highlights the importance of identifying the key aims in monitoring programmes, and outlines the different methods of sampling freshwater fish that can be used to meet these aims. We emphasise that investigators must address issues around sampling design, statistical power, species’ detectability, taxonomy, and ethics in their monitoring programmes. Additionally, programmes must ensure that high-quality monitoring data are properly curated and deposited in repositories that will endure. Through fostering improved practice in freshwater fish monitoring, this review aims to help programmes improve understanding of the processes that shape the Earth's freshwater ecosystems, and help protect these systems in face of rapid environmental change

Include or exclude? A review on the role and suitability of aquatic invertebrate neozoa as indicators in biological assessment with special respect to fresh and brackish European waters

This paper reviews published knowledge on how to deal with invasive species during biological quality assessments in European river systems for water management and assessments of ecological quality required, for example, by the European Water Frame Work Directive. The papers studied included international papers and some standards for water assessment. An overview of the current state of neozoa research showed that many different topics are treated, comprising biogeography and fauna records, species replacements and effectiveness of colonisation, life cycles, competition between native and invasive species, habitat quality and pathways of migration. Additionally, some papers have been published recently on the integration of neozoa in index-based assessment systems. Although the decline or increase of alien species populations and the corresponding impacts on indigenous populations were frequently observed, the mechanisms behind the invasions often remain hypothetical. In the reviewed papers, issues such as possible reasons for coexistence, tolerances, quality of habitat or water, life history traits and introduction of diseases were rarely covered. Few neozoa are sufficiently investigated to be categorised as indicators. After discussing the advantages and disadvantages of inclusion or exclusion, inclusion of invaders in assessments of both biodiversity (all species) and human impact (only species classified in their specific tolerance) is suggested. Further research is required to (1) update and assign ecological profiles of the non-indigenous species currently and (2) assess the effects of new invaders on native communities

The role of a freshwater tidal area with controlled reduced tide as feeding habitat for European eel (<i>Anguilla anguilla</i>, L.)

Implementation of the Controlled Reduced Tide (CRT) technique could increase the total surface of tidal freshwater marshes in Europe and ease implementation of restoration projects in coastal defense and riverine ecosystems. The goal was to determine whether a regularly flooded area connected to a freshwater tidal river could act as an important foraging area for European eel, and if so, to what extent the diet of eels in this flooding area differed from that of eels foraging in the river itself. The stomach contents of eels from the River Schelde were compared with eels from the Lippenbroek, an adjacent CRT area. Prey diversity (H') of individual eels was about four times higher in the Lippenbroek than in the River Schelde. Moreover, 12 prey categories in eel stomachs from the Lippenbroek were found whereas only three categories were retrieved from eels in the River Schelde. In the Lippenbroek, eels fed on terrestrial organisms (lumbricids, caterpillars and other insects), but also on fish and fish eggs and to a lesser extent on other aquatic prey (Lumbricullidae, chironomids and Hirudinea). In contrast, eels from the main river fed mainly on tubificids, fish, and some gammarids. Consequently, eels in the Schelde estuary are opportunistic feeders, but with a preference for large benthic prey. The number and weight of aquatic organisms ingested by eels in the Lippenbroek is not significantly different from the River Schelde. However, eels foraging in the Lippenbroek area had consumed significantly more terrestrial prey. Furthermore the total caloric value estimated for the ingested prey of eels from the Lippenbroek (derived from the literature) was about twice as high as that for eels from the River Schelde. While the condition index remained inconclusive, an Ancova revealed that eels captured in the Lippenbroek were significantly heavier for a given length than eels captured in the Schelde. The study showed that with a controlled reduced tide to restore lateral connectivity of large tidal rivers with their adjacent floodplains, high quality habitats for the European eel are created. These measures could significantly contribute to the production of eels in better condition, which have better chances to reproduce successfully. Hence, wetland restoration could enhance the recovery of the European eel stocks

The role of a freshwater tidal area with controlled reduced tide as feeding habitat for European eel (Anguilla anguilla, L.)

Implementation of the Controlled Reduced Tide (CRT) technique could increase the total surface of tidal freshwater marshes in Europe and ease implementation of restoration projects in coastal defense and riverine ecosystems. The goal was to determine whether a regularly flooded area connected to a freshwater tidal river could act as an important foraging area for European eel, and if so, to what extent the diet of eels in this flooding area differed from that of eels foraging in the river itself. The stomach contents of eels from the River Schelde were compared with eels from the Lippenbroek, an adjacent CRT area. Prey diversity (H') of individual eels was about four times higher in the Lippenbroek than in the River Schelde. Moreover, 12 prey categories in eel stomachs from the Lippenbroek were found whereas only three categories were retrieved from eels in the River Schelde. In the Lippenbroek, eels fed on terrestrial organisms (lumbricids, caterpillars and other insects), but also on fish and fish eggs and to a lesser extent on other aquatic prey (Lumbricullidae, chironomids and Hirudinea). In contrast, eels from the main river fed mainly on tubificids, fish, and some gammarids. Consequently, eels in the Schelde estuary are opportunistic feeders, but with a preference for large benthic prey. The number and weight of aquatic organisms ingested by eels in the Lippenbroek is not significantly different from the River Schelde. However, eels foraging in the Lippenbroek area had consumed significantly more terrestrial prey. Furthermore the total caloric value estimated for the ingested prey of eels from the Lippenbroek (derived from the literature) was about twice as high as that for eels from the River Schelde. While the condition index remained inconclusive, an Ancova revealed that eels captured in the Lippenbroek were significantly heavier for a given length than eels captured in the Schelde. The study showed that with a controlled reduced tide to restore lateral connectivity of large tidal rivers with their adjacent floodplains, high quality habitats for the European eel are created. These measures could significantly contribute to the production of eels in better condition, which have better chances to reproduce successfully. Hence, wetland restoration could enhance the recovery of the European eel stocks