Balancing engagement and neutrality in technology assessment

Should technology assessment take a stance – when, on what, and how? How to deal with its neutrality paradigm in times of anti-democratic tendencies

Base excision repair AP endonucleases and mismatch repair act together to induce checkpoint-mediated autophagy

Cellular responses to DNA damage involve distinct DNA repair pathways, such as mismatch repair (MMR) and base excision repair (BER). Using Caenorhabditis elegans as a model system, we present genetic and molecular evidence of a mechanistic link between processing of DNA damage and activation of autophagy. Here we show that the BER AP endonucleases APN-1 and EXO-3 function in the same pathway as MMR, to elicit DNA-directed toxicity in response to 5-fluorouracil, a mainstay of systemic adjuvant treatment of solid cancers. Immunohistochemical analyses suggest that EXO-3 generates the DNA nicks required for MMR activation. Processing of DNA damage via this pathway, in which both BER and MMR enzymes are required, leads to induction of autophagy in C. elegans and human cells. Hence, our data show that MMR- and AP endonuclease-dependent processing of 5-fluorouracil-induced DNA damage leads to checkpoint activation and induction of autophagy, whose hyperactivation contributes to cell death. © 2013 Macmillan Publishers Limited. All rights reserved

Space matters: incorporating mechanistically determined spatial patterns into projected impacts of climate change on stream temperature

River temperatures are increasing as a results of climate change, and combined with decreased summertime flows, coldwater species are becoming increasingly stressed. In order to conserve sensitive species, managers need an estimate of how the availability of summertime thermal refuges in rivers will change in the future. Here, we applied the DHSVM-RBM, an existing process-based water temperature model that has been shown to accurately represent temporal variance in water temperature over hours to years. We calibrated this model to empirical data for two case study watersheds (Siletz River, Oregon and Snoqualmie River, Washington) to also ensure representation of observed spatial heterogeneity during summer. We used the model to predict future spatiotemporal patterns in water temperature that may arise as a result of climate change and to assess Pacific salmon vulnerability. We then compared our predictions to those made by statistical models to assess the unique benefits and constraints of a process-based approach. We found that a substantial decrease of snowmelt, and subsequently summer flow, will drive increases in water temperature and spatial variability in future summers. Our vulnerability analysis suggested that for salmon and steelhead exposed to warm August temperatures, conditions are already stressful in lower portions of the case study watersheds, and unlikely to become better in the future. All models predicted generally similar spatial patterns of water temperature in the future; across models, future cool patches will be reduced in number and located farther upstream. However, projected increases in water temperature were strikingly different among models, ranging from about +5 oC in the Snoqualmie River as predicted by DHSVM-RBM, to a negligible change in both watersheds as predicted by statistical methods. This information can be used to identify locations where protection and restoration of coolwater habitats may be most important into the future

Normativität in der Technikfolgenabschätzung. Einleitung in das TATuP-Thema

Neutralität galt lange als unhinterfragte Grundlage im Selbstverständnis von Technikfolgenabschätzung (TA). Dieser Fokus verstellte allerdings den Blick darauf, dass normative Aspekte nicht außer Acht gelassen werden dürfen – sei es in den Ergebnissen von TA-Analysen oder in normativen Setzungen, die im TA-Prozess auftreten. Im TATuP-Thema dieses Heftes wird „Normativität in der TA“ auf drei Ebenen adressiert: in der Funktion von TA als Politikberatung, im Kontext des TA-Forschungsprozesses und in der Auseinandersetzung um ihren „normativen Kern“. Angesichts manch autoritärer Tendenzen auch in westlichen Demokratien ist die Debatte um die Rolle von Normativität in der TA heute besonders aktuell.Neutrality has long been considered a key prerequisite of technology assessment (TA). The need to stay neutral often obscured the importance of normative aspects of TA – be it in the findings or in normative settings in the TA process. The special topic addresses normativity in TA at three levels: (1) regarding TA’s role as policy advisor, (2) in the context of the research process, and (3) with respect to its “normative core”. The problem of normativity in TA gains significance in the light of recent authoritarian tendencies also in Western democracies

The Lectin-like Receptor KLRE1 Inhibits Natural Killer Cell Cytotoxicity

We report the cloning and functional characterization in the mouse and the rat of a novel natural killer (NK) cell receptor termed KLRE1. The receptor is a type II transmembrane protein with a COOH-terminal lectin-like domain, and constitutes a novel KLR family. Rat Klre1 was mapped to the NK gene complex. By Northern blot and flow cytometry using newly generated monoclonal antibodies, KLRE1 was shown to be expressed by NK cells and a subpopulation of CD3+ cells, with pronounced interstrain variation. Western blot analysis indicated that KLRE1 can be expressed on the NK cell surface as a disulphide-linked dimer. The predicted proteins do not contain immunoreceptor tyrosine-based inhibitory motifs (ITIMs) or a positively charged amino acid in the transmembrane domain. However, in a redirected lysis assay, the presence of whole IgG, but not of F(ab′)2 fragments of a monoclonal anti-KLRE1 antibody inhibited lysis of Fc-receptor bearing tumor target cells. Moreover, the tyrosine phosphatase SHP-1 was coimmunoprecipitated with KLRE1 from pervanadate-treated interleukin 2–activated NK cells. Together, our results indicate that KLRE1 may form a functional heterodimer with an as yet unidentified ITIM-bearing partner that recruits SHP-1 to generate an inhibitory receptor complex

Live imaging of cellular internalization of single colloidal particle by combined label-free and fluorescence total internal reflection microscopy

In this work we utilise the combination of label-free total internal reflection microscopy and total internal reflectance fluorescence (TIRM/TIRF) microscopy to achieve a simultaneous, live imaging of single, label-free colloidal particle endocytosis by individual cells. The TIRM arm of the microscope enables label free imaging of the colloid and cell membrane features, while the TIRF arm images the dynamics of fluorescent-labelled clathrin (protein involved in endocytosis via clathrin pathway), expressed in transfected 3T3 fibroblasts cells. Using a model polymeric colloid and cells with a fluorescently-tagged clathrin endocytosis pathway, we demonstrate that wide field TIRM/TIRF co-imaging enables live visualization of the process of colloidal particle interaction with the labelled cell structure, which is valuable for discerning the membrane events and route of colloid internalization by the cell. We further show that 500 nm model polystyrene colloid associates with clathrin, prior to and during its cellular internalisation. This association is not apparent with larger, 1 μm colloid, indicating an upper particle size limit for clathrin-mediated endocytosis

Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7 × 10−4 cm3 (STP) g–1 ± 2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ∼107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study’s geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying  that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids

Cochlea-inspired tonotopic resonators

The cochlea has long been the subject of investigation in various research fields due to its intriguing spiral architecture and unique sensing characteristics. One of its most interesting features is tonotopy, the abil- ity to sense acoustic waves at different spatial locations based on their frequency content. In this work, we propose a novel design for a tonotopic resonator, based on a cochlea-inspired spiral, which can dis- criminate the frequency content of elastic waves without the use of sub-wavelength resonators. The structure is the result of an optimization process to obtain a uniform distribution of displacement max- ima along its centreline for frequencies spanning nearly two-decades, while maintaining a compact design. Numerical simulations are performed to demonstrate the concept and experimental measure- ments to validate it on a 3D printed structure. The resulting frequency-dependent distribution is also shown to be a viable means to discriminate signals with various frequency components. We also show that for appropriate parameter ranges, the tonotopic behaviour can be inverted, i.e., lower frequencies can be made to concentrate in narrower regions, as happens in the real cochlea. The harnessed tonotopic features can be used as a fundamental principle to design structures with applications in areas such as non-destructive testing and vibration attenuation

Bone marrow stroma-derived PGE2 protects BCP-ALL cells from DNA damage-induced p53 accumulation and cell death

Background B cell precursor acute lymphoblastic leukaemia (BCP-ALL) is the most common paediatric cancer. BCP-ALL blasts typically retain wild type p53, and are therefore assumed to rely on indirect measures to suppress transformation-induced p53 activity. We have recently demonstrated that the second messenger cyclic adenosine monophosphate (cAMP) through activation of protein kinase A (PKA) has the ability to inhibit DNA damage-induced p53 accumulation and thereby promote survival of the leukaemic blasts. Development of BCP-ALL in the bone marrow (BM) is supported by resident BM-derived mesenchymal stromal cells (MSCs). MSCs are known to produce prostaglandin E2 (PGE2) which upon binding to its receptors is able to elicit a cAMP response in target cells. We hypothesized that PGE2 produced by stromal cells in the BM microenvironment could stimulate cAMP production and PKA activation in BCP-ALL cells, thereby suppressing p53 accumulation and promoting survival of the malignant cells. Methods Primary BCP-ALL cells isolated from BM aspirates at diagnosis were cocultivated with BM-derived MSCs, and effects on DNA damage-induced p53 accumulation and cell death were monitored by SDS-PAGE/immunoblotting and flow cytometry-based methods, respectively. Effects of intervention of signalling along the PGE2-cAMP-PKA axis were assessed by inhibition of PGE2 production or PKA activity. Statistical significance was tested by Wilcoxon signed-rank test or paired samples t test. Results We demonstrate that BM-derived MSCs produce PGE2 and protect primary BCP-ALL cells from p53 accumulation and apoptotic cell death. The MSC-mediated protection of DNA damage-mediated cell death is reversible upon inhibition of PGE2 synthesis or PKA activity. Furthermore our results indicate differences in the sensitivity to variations in p53 levels between common cytogenetic subgroups of BCP-ALL. Conclusions Our findings support our hypothesis that BM-derived PGE2, through activation of cAMP-PKA signalling in BCP-ALL blasts, can inhibit the tumour suppressive activity of wild type p53, thereby promoting leukaemogenesis and protecting against therapy-induced leukaemic cell death. These novel findings identify the PGE2-cAMP-PKA signalling pathway as a possible target for pharmacological intervention with potential relevance for treatment of BCP-ALL