Project description:Increased concentrations of dissolved organic carbon (DOC), often labelled "browning", is a current trend in northern, particularly boreal, freshwaters. The browning has been attributed to the recent reduction in sulphate (S) deposition during the last 2 to 3 decades. Over the last century, climate and land use change have also caused an increasing trend in vegetation cover ("greening"), and this terrestrially fixed carbon represents another potential source for export of organic carbon to lakes and rivers. The impact of this greening on the observed browning of lakes and rivers on decadal time scales remains poorly investigated, however. Here, we explore time-series both on water chemistry and catchment vegetation cover (using NDVI as proxy) from 70 Norwegian lakes and catchments over a 30-year period. We show that the increase in terrestrial vegetation as well as temperature and runoff significantly adds to the reduced SO4-deposition as a driver of freshwater DOC concentration. Over extended periods (centuries), climate mediated changes in vegetation cover may cause major browning of northern surface waters, with severe impact on ecosystem productivity and functioning.
Project description:Many estuaries are becoming increasingly eutrophic from human activities within their catchments. Nutrient loads often are used to assess risk of eutrophication to estuaries, but such data are expensive and time consuming to obtain. We compared the percent of fertilized land within a catchment, dissolved inorganic nitrogen loads, catchment to estuary area ratio and flushing time as predictors of the proportion of macroalgae to total vegetation within 14 estuaries in south-eastern Australia. The percent of fertilized land within the catchment was the best predictor of the proportion of macroalgae within the estuaries studied. There was a transition to a dominance of macroalgae once the proportion of fertilized land in the catchment exceeded 24%, highlighting the sensitivity of estuaries to catchment land use.
Project description:In the last few decades, the field of ancient DNA has taken a new direction towards using sedimentary ancient DNA (sedaDNA) for studying human and mammalian population dynamics as well as past ecosystems. However, the screening of numerous sediment samples from archaeological sites remains a time-consuming and costly endeavor, particularly when targeting hominin DNA. Here, we present a novel high-throughput method that facilitates the fast and efficient analysis of sediment samples by applying a pooled testing approach. This method combines multiple extracts, enabling early parallelization of laboratory procedures and effective aDNA screening. Pooled samples with detectable aDNA signals undergo detailed analysis, while empty pools are discarded. We have successfully applied our method to multiple sediment samples from Middle and Upper Paleolithic sites in Europe, Asia, and Africa. Notably, our results reveal that an aDNA signal remains discernible even when pooled with four negative samples. We also demonstrate that the DNA yield of double-stranded libraries increases significantly when reducing the extract input, potentially mitigating the effects of inhibition. By embracing this innovative approach, researchers can analyze large numbers of sediment samples for aDNA preservation, achieving significant cost reductions of up to 70% and reducing hands-on laboratory time to one-fifth.
Project description:Long-term water temperature records are necessary for better understanding climate change impacts on freshwaters. We reconstruct summer water temperatures from three climatically sensitive mountain lakes in Austria using paleolimnological methods aiming to examine long-term thermal dynamics and lakes' responses to regional climate variability since the Little Ice Age. Our results indicate divergent trends for the lakes. In two of the lakes, which are located at the sunny southern slope of mountains, water temperature has increased several degrees concurrent with the observed air temperature increase. In contrast, no change is observed in the reconstructed water temperatures of a shaded lake, located at the northern slope, where also the ecological and thermal changes are most subtle. The results indicate the importance of cold water inputs, such as snowmelt and groundwater, on lakes' thermal conditions and suggest that watershed characteristics and lake stratification play a major role in defining the lake-specific thermal regime.
Project description:Abelin JG, Patel J, Lu X, Feeney CM, Fagbami L, Creech AL, Hu R, Lam D, Davison D, Pino L, Qiao JW, Kuhn E, Officer A,Li J, Abbatiello S, Subramanian A, Sidman R, Snyder E, Carr SA, Jaffe JD. Mol Cell Proteomics, 2016. Profiling posttranslational modifications represents an alternative dimension to gene expression data in characterizing cellular processes, as genetic processes alone are not sufficient to explain the entirety of biochemical mechanisms or disease etiology. For example, some cellular phenotypes resulting from chemical perturbations are partially or entirely mediated by changes in cell signaling through protein phosphorylation. To access this dimension of cellular information, we sought to develop a common platform on which cellular phosphosignaling responses could be profiled across thousands of samples. To this end, we developed a targeted MS assay that profiles a reduced-representation set of phosphopeptides that we show to be strong indicators of cellular responses to chemical perturbagens.
Project description:This manuscript documents geological master data and X-ray fluorescence (XRF) data of a standardized 8*8 km sampling grid of the entire Weiße Elster catchment in Central Germany. Further, the manuscript documents XRF data of a refined 4*4 km sampling grid in the proximity of Salsitz floodplain transect as well as grain size data and XRF data of Salsitz SC40 core that was recovered from the Weiße Elster floodplain. The data provide opportunities for hydro-sedimentary provenance analyses as presented in the corresponding research article by Ballasus et al. [1].
Project description:After perception of vegetation proximity by the phytochrome photoreceptors, shade-avoider plants initiate a set of responses known as the Shade Avoidance Syndrome (SAS). Shade perception by the phytochrome B (phyB) photoreceptor unleashes the PHYTOCHROME INTERACTING FACTORs (PIFs) and initiates SAS responses. In Arabidopsis thaliana seedlings, shade perception involves rapid and massive changes in gene expression, increases auxin production and promotes hypocotyl elongation. Other components, such as phyA and ELONGATED HYPOCOTYL 5 (HY5), also participate in the shade regulation of the hypocotyl elongation response by repressing it. However, it remains unclear why and how so many regulators with either positive or negative activities modulate the same response. Our physiological, genetic, cellular and transcriptomic analyses showed that (1) these components are organized in two main branches or modules (phyA/HY5 and PIFs/HFR1/SAV3) and (2) the connection between them is dynamic and changes with the time of shade exposure. We propose a model for the regulation of shade-induced hypocotyl elongation in which the temporal and spatial functional importance of the various SAS regulators analyzed in here helps to explain the co-existence of differentiated regulatory branches with overlapping activities. Despite the temporal differences observed between phyA, HY5 and PIFs/HFR1/SAV3, their activities overlap and eventually converge in controlling hypocotyl elongation. Hence, we aimed to further investigate possible convergence points between these two groups of regulators.To expand our understanding of the role and interaction of HY5 and PIF4, PIF5 and PIF7 (PIF457) activities, we carried out RNA sequencing (RNA-seq) of seedlings exposed to different times of shade exposure of four genotypes: wild-type (Col-0), the single mutant hy5, the triple pif457 and the quadruple hy5 pif457.