The breakdown of allochthonous organic matter, is a central step in nutrient cycling in stream ecosystems. There is concern that increased temperatures from climate change will alter the breakdown ...rate of organic matter, with important consequences for the ecosystem functioning of alpine streams. This study investigated the rate of leaf litter breakdown and how temperature and other factors such as microbial and invertebrate activities influenced this over elevational and temporal gradients. Dried leaves of Snow Gum (Eucalyptus pauciflora) and cotton strips were deployed in coarse (6 mm), and fine (50 μm) mesh size bags along an 820 m elevation gradient. Loss of mass in leaf litter and cotton tensile strength per day (k per day), fungal biomass measured as ergosterol concentration, invertebrate colonization of leaf litter, and benthic organic matter (mass and composition) were determined. Both microbial and macroinvertebrate activities were equally important in leaf litter breakdown with the abundance of shredder invertebrate taxa. The overall leaf litter breakdown rate and loss of tensile strength in cotton strips (both k per day) were greater during warmer deployment periods and at lower elevations, with significant positive relationships between mean water temperature and leaf breakdown and loss of tensile strength rate, but no differences between sites, after accounting for the effects of temperature. Despite considerably lower amounts of benthic organic matter in streams above the tree line relative to those below, shredders were present in coarse mesh bags at all sites. Ergosterol concentration was greater on leaves in coarse mesh bags than in fine mesh bags, implying differences in the microbial communities. The importance of water temperatures on the rate of leaf litter breakdown suggests the potential effects of climate change‐induced temperature increases on ecological processes in such streams.
We aimed at understanding how spatial and temporal water temperatures influenced AOM breakdown in alpine streams. Microbial and macroinvertebrate activities were monitored and showed to be elevated at lower elevations and during warmer periods. Climate change induced warming will therefore potentially change alpine stream ecosystem, standing biomass and promote increased nutrient cycling through AOM breakdown.
Some of the highest exposures to air pollutants in developing countries occur inside homes where solid biofuel, particularly wood fuel, is used for daily cooking. A relatively high proportion of the ...world population living in these countries is exposed to increased levels of indoor air pollutants produced by inefficiently burning stoves. Inhalation of these pollutants may have serious consequences, which are highlighted in this paper, for the respiratory health of the people who have been exposed.
The 18 kDa translocator protein (TSPO) is a target for the development of imaging agents to detect neuroinflammation. The clinical utility of second-generation TSPO ligands has been hindered by the ...presence of a polymorphism, rs6971, which causes a non-conservative substitution of alanine for threonine at amino acid residue 147 (TSPO A147T). Given the complex nature of TSPO binding, and the lack of non-discriminating high-affinity ligands at both wild type and A147T forms of TSPO, a series of novel TSPO ligands containing various heterocyclic scaffolds was developed to explore the pharmacophoric drivers of affinity loss at TSPO A147T. In general, N-benzyl-N-methyl-substituted amide ligands showed increased affinity at TSPO A147T, and a pyrazolopyrimidine acetamide containing this motif displayed low nanomolar binding affinities to both TSPO forms.
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•Optimal binding to both TSPO isoforms is dependent on both the heterocyclic scaffold and substituents on the acetamide motif.•The nature of the pyrazolopyrimidine scaffold was found to be a promising scaffold for TSPO ligands.•Lowered discrimination at A147T TSPO is predominantly seen with N-benzyl-N-methyl ligands.•Docking studies were used to examine how each heterocyclic scaffold binds to both WT and A147T TSPO.
This study explored biofilm metabolism as a functional indicator of ecological responses to dissolved organic carbon and inorganic nutrients from managed dam releases. We hypothesised that the dam ...releases would stimulate epilithic biofilm community respiration (CR), and trigger a larger increase in biofilm CR relative to gross primary production (GPP). We predicted that biofilm respiration would be related to water column dissolved carbon and nutrient concentrations. Tiles colonised with epilithic biofilm were exposed to dam release waters in a stream-side mesocosm system that separated out the physical effects of flow velocity. Biofilm CR increased during two of three releases, and increases in CR were larger relative to GPP during all three releases. Biofilm CR was not linearly related to dissolved resources or abiotic environmental variables. These results show that managed dam releases can influence biofilm metabolism via a mechanism independent from the direct physical effects of increased flow velocity. This study provides new insights into the complex pathways through which managed dam releases may influence ecological processes. The stimulation of benthic CR through physical and chemical variations in dam water is a potential mechanism through which dam releases may influence biogeochemical processing and energy flow through the riverine food web.
