Using fractionation profile of potentially toxic elements in soils to investigate their accumulation in Tilia sp. leaves in urban areas with different pollution levels

Optimal uptake of micronutrients (B, Cu, Fe, Mn, and Zn) and managing the potentially toxic elements (PTEs) (Co, Cr, Ni, Pb, and Sr) in the ranges not detrimental to plant function may be linked to improving plants’ healthy growth and the ability to provide ecosystem services. We investigated concentrations, mobility, and potential availability of potentially toxic elements (PTEs) in soil samples from polluted and non-polluted municipal parks in Reading (UK) and Belgrade (Serbia) and their impact on elemental concentrations in Tilia leaves. We aimed to identify common limiting factors potentially affecting the growth/healthy function of this widely-used tree species. Levels of all elements in soil were below limits established by the directive of European Communities, except for Ni at Belgrade sites. Content of Co, Cr, Cu, Fe, Ni, Pb, and Zn in soluble fraction at all locations was <10%, indicating low mobility; B showed moderate mobility (11.1%–20.7%), Mn (6.5%–55.6%), and Sr—high (44%–76.3%). Principal Component Analysis of Tilia leaf tissues showed a different capacity for uptake/accumulation of PTEs in different locations. Findings indicate the complexity of local edaphic influences on plants’ elemental uptake and the risk of those leading to deficiency of important micronutrients, which may impede trees’ function and thus the ability to optimally provide ecosystem services

Primary cilia sensitize endothelial cells to BMP and prevent excessive vascular regression

Blood flow shapes vascular networks by orchestrating endothelial cell behavior and function. How endothelial cells read and interpret flow-derived signals is poorly understood. Here, we show that endothelial cells in the developing mouse retina form and use luminal primary cilia to stabilize vessel connections selectively in parts of the remodeling vascular plexus experiencing low and intermediate shear stress. Inducible genetic deletion of the essential cilia component intraflagellar transport protein 88 (IFT88) in endothelial cells caused premature and random vessel regression without affecting proliferation, cell cycle progression, or apoptosis. IFT88 mutant cells lacking primary cilia displayed reduced polarization against blood flow, selectively at low and intermediate flow levels, and have a stronger migratory behavior. Molecularly, we identify that primary cilia endow endothelial cells with strongly enhanced sensitivity to bone morphogenic protein 9 (BMP9), selectively under low flow. We propose that BMP9 signaling cooperates with the primary cilia at low flow to keep immature vessels open before high shear stress-mediated remodeling

Electrical stimulation of the forearm:a method for transmitting sensory signals from the artificial hand to the brain

This research is in line with an important comment from the first amputee who tried the prosthetic hand with tactile feedback developed within the Smarthand project [1]. While trying the system with tactile feedback the patient said: "It's a feeling I have not had in a long time. When I grab something tightly I can feel it in the fingertips. It's strange since I don't have them anymore! It's amazing." We describe here the instrumentation and methods for testing the abilities of humans to discriminate sensations generated by electrical stimulation applied to the skin on the forearm. The instruments allowed testing of electrical stimulation with various properties (pulse duration, intensity, and rate). We tested the perception and pain thresholds, with the emphasis that comfortable sensations are a must. During the tests subjects were asked to locate the point on the skin that was stimulated and describe their perception of the elicited sensation. Results of first tests with small concentric electrodes suggest that non-amputees can distinguish up to seven perceptual qualities (the most common one was vibration, followed by tingling and tickling). Certain sensations had a higher occurrence rate along one axial line of the forearm than another of the forearm. In terms of spatial acuity, the subjects had more difficulties in distinguishing between the positions in the axial direction of the forearm compared with the circumferential direction. These results guided the design of the new array electrode with multiple cathodes and anodes positioned circumferential to the forearm. The results of the tests conducted with this electrode design showed high location discernment accuracy, and demonstrated the ability to memorize and later accurately recall six different electrical ?messages? created by delivering electrical stimulation onto three different electrode pads with two different stimulation parameters.</jats:p

Endothelial Cell Orientation and Polarity Are Controlled by Shear Stress and VEGF Through Distinct Signaling Pathways

Vascular networks form, remodel and mature under the influence of multiple signals of mechanical or chemical nature. How endothelial cells read and interpret these signals, and how they integrate information when they are exposed to both simultaneously is poorly understood. Here, we show using flow-induced shear stress and VEGF-A treatment on endothelial cells in vitro, that the response to the magnitude of a mechanical stimulus is influenced by the concentration of a chemical stimulus, and vice versa. By combining different flow levels and different VEGF-A concentrations, front-rear polarity of endothelial cells against the flow direction was established in a flow and VEGF-A dose-response while their alignment with the flow displayed a biphasic response depending on the VEGF-A dose (perpendicular at physiological dose, aligned at no or pathological dose of VEGF-A). The effect of pharmaceutical inhibitors demonstrated that while VEGFR2 is essential for both polarity and orientation establishment in response to flow with and without VEGF-A, different downstream effectors were engaged depending on the presence of VEGF-A. Thus, Src family inhibition (c-Src, Yes, Fyn together) impaired alignment and polarity without VEGF-A while FAK inhibition modified polarity and alignment only when endothelial cells were exposed to VEGF-A. Studying endothelial cells in the aortas of VEGFR2(Y949F) mutant mice and SRCiEC-KO mice confirmed the role of VEGFR2 and specified the role of c-SRC in vivo. Endothelial cells of VEGFR2(Y949F) mutant mice lost their polarity and alignment while endothelial cells from SRCiEC-KO mice only showed reduced polarity. We propose here that VEGFR2 is a sensor able to integrate chemical and mechanical information simultaneously and that the underlying pathways and mechanisms activated will depend on the co-stimulation. Flow alone shifts VEGFR2 signaling toward a Src family pathway activation and a junctional effect (both in vitro and in vivo) while flow and VEGF-A together shift VEGFR2 signaling toward focal adhesion activation (in vitro) both modifying cell responses that govern orientation and polarity