The role of regional tectonics and magma flow coupling versus magmatic processes in generating contrasting magmatic fabrics within the Land’s End Granite, Cornwall.

The Lower Permian Land’s End Granite intruded Upper Devonian metasedimentary and metavolcanic rocks of the Mylor Slate Formation that had been previously deformed and regionally metamorphosed during Variscan convergence. Structural studies of the host rocks have been used to infer that granite generation and emplacement occurred in response to regional D3 NNW-SSE extension of moderately thickened crust. Detailed field mapping along the northwestern margin of the granite reveals complex magmatic fabrics defined by K-feldspar and biotite. Close to the pluton margins, a gently NW or SE dipping magmatic foliation is defined by the preferred orientation of K-feldspar and biotite. Further from the pluton margin, the foliation dips moderately NW or SE, or occurs in steeply dipping NW-SE trending zones with very strong fabrics. Magmatic foliations tend towards parallelism with the margins of stoped blocks over a distance of one to several metres, but there is no evidence that the blocks deform a previously formed magmatic fabric. The Land’s End Granite exhibits low degrees of anisotropy of magnetic susceptibility (AMS) and biotite is the carrier. The AMS foliation generally dips gently to the NW or SE and contains two, near-orthogonal lineations that trend ENEWSW and N-S. The variations in magnetic lineation orientation correlate with the intensity of the macroscopic feldspar fabric. In zones where the feldspar fabric is strongly developed, the AMS has a NW plunging lineation, whereas in zones where the feldspar fabric is weak, the AMS has a NE plunging lineation. There is close correspondence between the orientation of the AMS fabrics and D3 structures within the Mylor Slate Formation. However, it is possible that there was only partial coupling between the granite magma and extensional deformation of the host rock. Stoped blocks and host rock irregular contacts exert a significant control on fabric orientation

Creating a root architecture model: taprooted or adventitious-rooted Plantago lanceolata

Herbaceous plants can form root systems by investing in one main taproot or many adventitious roots. While monocots have adventitious systems, eudicots can have either type in different species and even within a single species depending on its age, environment, or injury. Although clearly different, we know little about their relationship to ecological functions and response. We used Plantago lanceolata, a species that can have either root system and forms adventitious buds on roots, to test methods to form plants with a taproot, adventitious roots, or that grow from a root fragment, to obtain individuals of comparable size. We first evaluated injury response and root traits, then used selected models in a pilot study. For the pilot study, we selected an adventitious root model procedure with root removal from approximately 5-day-old seedlings at 1-2 mm below the stem base (hypocotyl) and rootsprout model of the topmost 4 cm of the taproot from 4-week-old plants. We planted adventitious and taprooted plants in three urban lawns and harvested them after three months. Adventitious and tap-rooted plants were similarly affected by competition, producing lower biomass of leaves and stem in more competitive lawns. Root and leaf traits were consistent regardless of architecture type. Plantago lanceolata fully compensated early loss of the taproot when injured at about 10 days old, and in mesic conditions both root architectures perform similarly. These model systems can be used for investigating the role of root architecture in a variety of ecological topics, for example, its function along a moisture gradient.publishedVersio

Supernatants from lymphocytes stimulated with Bacillus Calmette-Guerin can modify the antigenicity of tumours and stimulate allogeneic T-cell responses

BACKGROUND: Reduced expression of class 1 human leucocyte antigens (HLA1) is often a mechanism by which tumours evade surveillance by the host immune system. This is often associated with an immune function that is unable to mount appropriate responses against disease, which can result in a state that favours carcinogenesis. METHODS: In the current study, we have explored the effects of Bacillus Calmette-Guerin (BCG) on the cytokine output of leucocytes, which is a key determinant in generating antitumour action, and have also assessed the effect of these cytokine cocktails on HLA1 expression in solid tumour cell lines. RESULTS: BCG potently activated a broad range of leucocytes, and also enhanced the production of cytokines that were Th(1)-predominant. Supernatants from BCG-treated leucocytes significantly increased the expression of HLA1 on the surface of cancer cell lines, which correlated with increased cytolytic T-cell activity. We also showed that the increased HLA1 expression was associated with activation of intracellular signalling pathways, which was triggered by the increases in the Th(1)-cytokines interferon-γ and tumour necrosis factor-α, as counteracting their effects negated the enhancement. CONCLUSION: These studies reaffirm the role of BCG as a putative immunotherapy through their cytokine-modifying effects on leucocytes and their capacity to enhance tumour visibility

Decrypting magnetic fabrics (AMS, AARM, AIRM) through the analysis of mineral shape fabrics and distribution anisotropy

The fieldwork was supported by the DIPS project (grant no. 240467) and the MIMES project (grant no. 244155) funded by the Norwegian Research Council awarded to O.G. O.P.'s position was funded from Y-TEC.Anisotropy of magnetic susceptibility (AMS) and anisotropy of magnetic remanence (AARM and AIRM) are efficient and versatile techniques to indirectly determine rock fabrics. Yet, deciphering the source of a magnetic fabric remains a crucial and challenging step, notably in the presence of ferrimagnetic phases. Here we use X-ray micro-computed tomography to directly compare mineral shape-preferred orientation and spatial distribution fabrics to AMS, AARM and AIRM fabrics from five hypabyssal trachyandesite samples. Magnetite grains in the trachyandesite are euhedral with a mean aspect ratio of 1.44 (0.24 s.d., long/short axis), and > 50% of the magnetite grains occur in clusters, and they are therefore prone to interact magnetically. Amphibole grains are prolate with magnetite in breakdown rims. We identified three components of the petrofabric that influence the AMS of the analyzed samples: the magnetite and the amphibole shape fabrics and the magnetite spatial distribution. Depending on their relative strength, orientation and shape, these three components interfere either constructively or destructively to produce the AMS fabric. If the three components are coaxial, the result is a relatively strongly anisotropic AMS fabric (P’ = 1.079). If shape fabrics and/or magnetite distribution are non-coaxial, the resulting AMS is weakly anisotropic (P’ = 1.012). This study thus reports quantitative petrofabric data that show the effect of magnetite distribution anisotropy on magnetic fabrics in igneous rocks, which has so far only been predicted by experimental and theoretical models. Our results have first-order implications for the interpretation of petrofabrics using magnetic methods.Publisher PDFPeer reviewe