Assessment of Soil Structure and Root Patterns by Means of Micro-X-ray Computed Tomography in Temperate Grassland Sites

Grassland sites are important ecosystems delivering essential ecosystem services such as carbon storage and filtering of water. Adequate management necessitates a better understanding of soil ecological processes in grassland ecosystems. Of special interest is the relationship between soil structure and root development. In a project within the Biodiversity Exploratory Initiative (http://www.biodiversity-exploratories.de), undisturbed soil cores from 31 grassland plots from Swabian Alb Biodiversity exploratory in Germany were investigated by means of X-ray micro computed tomography. This allows the simultaneous determination of soil physical and root parameters in one sample. VG StudioMax® version 2.1 was used to apply a combination of histogram analysis and spatial transformation to distinguish between solids, root system, and pore space. The results of this study reveal close relationships between the soil physical state and root development in grassland soil. Roots have been identified as important contributors to the prevention of soil compaction. Whereas soil compaction is a major threat to soil functions and ecosystem services, which should be mitigated with enhanced awareness of root growth, e.g. with the right choice of varieties, implementation of legumes, adapted management

The Role of the Tumour Suppressor p53 in the Elimination of Hepatitis B Virus-infected Hepatocytes - Implications for Viral Clearance

Chronic hepatitis B virus (HBV) infection is a major risk factor for the development of hepatocellular carcinoma (HCC) and more than 350 million people are chronically infected with HBV worldwide. The non-cytopathic hepatitis B virus is acting as a “stealth” virus and is, therefore, hardly detected by the innate immune system, thus, contributing to chronicity. So far, it is known that infiltrating cytotoxic T cells are the main effector cells involved in the elimination of HBV-infected hepatocytes. However, the direct molecular mechanisms through which HBV-infected cells are eliminated by the immune system, as well as the signalling pathways up-regulated in infected host cells to combat the virus remain unclear. The present study was designed to investigate both the influence of the hepatocytes’ p53 status on the outcome of HBV infection and vice versa the influence of HBV infection on p53 and p53 target gene activation in hepatocytes. In summary, hepatitis B virus infection triggers the activation of the DNA damage response leading to the stabilization and activation of the tumour suppressor p53 in an ATM/ATR-dependent manner. Activation of p53 upon HBV infection induces the up-regulation of different p53 target genes playing important roles in the extrinsic and the intrinsic apoptosis signalling pathway. In the present study the functionality of the CD95 pathway has been identified to be an essential factor for the elimination of HBV-infected hepatocytes. The expression of proteins involved in apoptosis signalling leads to the alteration of the mitochondrial membrane potential, the subsequent release of cytochrome c and finally to apoptosis induction of HBV-infected hepatocytes. Furthermore, HBV infection triggers the induction of CD95L gene transactivation in an AP-1-dependent manner which leads to the, so far, unrecognized capability of virus-infected hepatocytes to secret CD95L by themselves. Our results propose a new p53-dependent model for virus elimination in HBV-infected hepatocytes and show that p53 beyond its role as a tumour suppressor also plays an important role in viral clearance. The identification of prominent members of the apoptosis signalling pathways as crucial proteins activated upon HBV-infection demonstrate an underlying mechanism for the diverse outcomes (clearance vs. chronicity) of a HBV infection. The significant contribution of p53 in cellular antiviral defence suggests a potential implication in the pathogenesis of HBV infection and opens new therapeutic options via stabilization of p53

Discrimination of soil phases by dual energy x-ray tomography

Numerous soil ecological functions are influenced by soil structure through its impact on spatial and temporal distributions of soil particles, water, and air within the soil profile. The nondestructive technique of x‐ray computed tomography (CT) was used for studying soil structure. X‐ray attenuation determined for two energy levels (80 kV and 120 kV) was used to calculate distributions of water, air, and solids, as well as the voxel dry bulk density for two silt loam subsoils. The spatial resolution during scanning was 0.25 mm in the horizontal and 1 mm in the vertical direction. For different voxel sizes, the weighted mean of the derived volumetric water, air, and solid contents, and the dry bulk densities agreed with the sample's phase composition and dry bulk density obtained by weighing. The use of dual energy scanning to study the heterogeneity of soil structure and the spatial distribution of water, air, and solids is discussed

High-resolution computed tomography reconstructions of invertebrate burrow systems

The architecture of biogenic structures can be highly influential in determining species contributions to major soil and sediment processes, but detailed 3-D characterisations are rare and descriptors of form and complexity are lacking. Here we provide replicate high-resolution micro-focus computed tomography (μ-CT) data for the complete burrow systems of three co-occurring, but functionally contrasting, sediment-dwelling inter-tidal invertebrates assembled alone, and in combination, in representative model aquaria. These data (≤2,000 raw image slices aquarium−1, isotropic voxel resolution, 81 μm) provide reference models that can be used for the development of novel structural analysis routines that will be of value within the fields of ecology, pedology, geomorphology, palaeobiology, ichnology and mechanical engineering. We also envisage opportunity for those investigating transport networks, vascular systems, plant rooting systems, neuron connectivity patterns, or those developing image analysis or statistics related to pattern or shape recognition. The dataset will allow investigators to develop or test novel methodology and ideas without the need to generate a complete three-dimensional computation of exemplar architecture

Homozygous whole body Cbs knockout in adult mice features minimal pathology during ageing despite severe homocysteinemia

Deficiencies in Cystathionine-β-synthase (CBS) lead to hyperhomocysteinemia (HHCy), which is considered a risk factor for cardiovascular, bone and neurological disease. Moreover, CBS is important for the production of cysteine, hydrogen sulfide (H2 S) and glutathione. Studying the biological role of CBS in adult mice has been severely hampered by embryological disturbances and perinatal mortality. To overcome these issues and assess the effects of whole-body CBS deficiency in adult mice, we engineered and characterized a Cre-inducible Cbs knockout model during ageing. No perinatal mortality occurred before Cbs-/- induction at 10 weeks of age. Mice were followed until 90 weeks of age and ablation of Cbs was confirmed in liver and kidney but not in brain. Severe HHCy was observed in Cbs-/- (289 ± 58 µM) but not in Cbs+/- or control mice (<10 µM). Cbs-/- showed impaired growth, facial alopecia, endothelial dysfunction in absence of increased mortality, and signs of liver or kidney damage. CBS expression in skin localized to sebaceous glands and epidermis, suggesting local effects of Cbs-/- on alopecia. Cbs-/- showed increased markers of oxidative stress and senescence but expression of other H2 S producing enzymes (CSE and 3-MST) was not affected. CBS deficiency severely impaired H2 S production capacity in liver, but not in brain or kidney. In summary, Cbs-/- mice presented a mild phenotype without mortality despite severe HHCy. The findings demonstrate that HHCy is not directly linked to development of end organ damage

Nitric Oxide Synthase Inhibition Enhances the Antitumor Effect of Radiation in the Treatment of Squamous Carcinoma Xenografts

This study tests whether the nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine (L-NNA), combines favorably with ionizing radiation (IR) in controlling squamous carcinoma tumor growth. Animals bearing FaDu and A431 xenografts were treated with L-NNA in the drinking water. IR exposure was 10 Gy for tumor growth and survival studies and 4 Gy for ex vivo clonogenic assays. Cryosections were examined immunohistochemically for markers of apoptosis and hypoxia. Blood flow was assayed by fluorescent microscopy of tissue cryosections after i.v. injection of fluorospheres. Orally administered L-NNA for 24 hrs reduces tumor blood flow by 80% (p<0.01). Within 24 hrs L-NNA treatment stopped tumor growth for at least 10 days before tumor growth again ensued. The growth arrest was in part due to increased cell killing since a combination of L-NNA and a single 4 Gy IR caused 82% tumor cell killing measured by an ex vivo clonogenic assay compared to 49% by L-NNA or 29% by IR alone. A Kaplan-Meyer analysis of animal survival revealed a distinct survival advantage for the combined treatment. Combining L-NNA and IR was also found to be at least as effective as a single i.p. dose of cisplatin plus IR. In contrast to the in vivo studies, exposure of cells to L-NNA in vitro was without effect on clonogenicity with or without IR. Western and immunochemical analysis of expression of a number of proteins involved in NO signaling indicated that L-NNA treatment enhanced arginase-2 expression and that this may represent vasculature remodeling and escape from NOS inhibition. For tumors such as head and neck squamous carcinomas that show only modest responses to inhibitors of specific angiogenic pathways, targeting NO-dependent pro-survival and angiogenic mechanisms in both tumor and supporting stromal cells may present a potential new strategy for tumor control

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

14 p.Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change