Functional significance of genotoxicity in fish germ cells

The aquatic environment is becoming increasingly contaminated by pollutants having a genotoxic potential towards organisms and in particular in fish. Such genotoxins are prone to affect directly offspring or indirectly through the reproductive process. All this could influence recruitment rate and hence the population dynamics. However, assessment of the ecological risks associated with environmental genotoxic exposure is usually based on individual responses. Thus, there is a need for a better understanding of the long term and population level implications of genotoxic insults in fish. While low levels of DNA damage in somatic cells and oocytes can be efficiently repaired, mature sperm cells, i.e. spermatozoa, are susceptible to accumulate damage due to their lack of repair capacity. The present work aims to track the transfer of toxic effects across generations by studying the link between the level of DNA damage in fish sperm, and the rate of development abnormalities measured in the offspring after parental exposure to the model genotoxicant MMS. Three different fish species were chosen based either on their ecological importance or on their reproduction behavior, respectively brown trout (Salmo trutta), Arctic charr (Salvelinus alpinus) and threespine stickleback (Gasterosteus aculeatus). Results show a significant increase in sperm DNA damage measured with the comet assay in exposed organisms. This damage did not impact on fertilization success but led further to a significant increase in embryo abnormality rate at early embryonic and late larval stages, and further delayed growth in exposed group compared to the control

Ecotoxicological risk assessment linked to infilling quarries with treated dredged seaport sediments

International audienceThe dredged sediments of polluted seaports now raise complex management problems since it is no longer possible to discharge them into the sea. This results in the need to manage them on land, raising other types of technical, economic and environmental problems. Regarding the technical and economic dimensions, traditional waste treatment methods have proved to be poorly adapted, due to very high costs and low absorbable volumes. In this context, filling quarries in coastal areas with treated sediments could represent an interesting alternative for these materials. Nevertheless, for the environmental dimension, it is necessary to demonstrate that this possibility is harmless to inland ecosystems. Consequently, a specific ecotoxicological risk assessment methodology has been formulated and tested on three sediments taken from seaboards of France, in view to providing an operational and usable tool for the prior validation of any operation to fill quarries with treated seaport sediments. This method incorporates the formulation of a global conceptual model of the scenario studied and the definition of protocols for each of its steps: the characterisation of exposures (based on a simulation of sediment deposit), the characterisation of effects (via the study of sediments ecotoxicity), and the final ecotoxicological risk assessment performed as a calculation of a risk quotient. It includes the implementation in parallel of two types of complementary approach: the "substances" approach derived from the European methodology for assessing new substances placed on the market, and the "matrix" approach which is similar to methods developed in France to assess ecological risks in other domains (waste management, polluted site management, ...). The application of this dual approach to the three sediments tested led to conclude with reliability that the project to deposit sediments "1" and "2" presented a low risk for the peripheral aquatic ecosystems while sediment "3" presented a high risk

Physical training and hypertension have opposite effects on endothelial brain-derived neurotrophic factor expression

Aims Changes in circulating brain-derived neurotrophic factor (BDNF) levels were reported in patients with or at risk for cardiovascular diseases associated with endothelial dysfunction, suggesting a link between BDNF and endothelial functionality. However, little is known on cardiovascular BDNF. Our aim was to investigate levels/localization, function, and relevance of cardiovascular BDNF. Methods and results BDNF levels (western blotting) and localization (immunostaining) were assessed in the heart and aorta from rats with impaired (spontaneously hypertensive rats [SHR]), normal (Wistar Kyoto rats [WKY]), and improved (SHR and WKY subjected to physical training) endothelial function. BDNF levels were also measured in cultured endothelial cells (CECs) subjected to low and high shear stress. The cardiovascular effects of BDNF were investigated in isolated aortic rings and hearts. The results showed high BDNF levels in the heart and aorta, the expression being prominent in endothelial cells as compared with other cell types. Exogenous BDNF vasodilated aortic rings but changed neither coronary flow nor cardiac contractility. Hypertension was associated with decreased expression of BDNF in the endothelium, whereas physical training led to endothelial BDNF up-regulation not only in WKY but also in SHR. Exposure of CECs to high shear stress stimulated BDNF production and secretion. Conclusion Cardiovascular BDNF is mainly localized within endothelial cells in which its expression is dependent on endothelial function. These results open new perspectives on the role of endothelial BDNF in cardiovascular healt

Room Temperature Mott Hopping and Spin pumping Characterization of Amorphous Gd-alloyed Bi2Se3

Disordered films have gained intense interest because of their possibility for spintronics applications by benefiting from other exotic transport properties. Here, we have fabricated disordered Gd-alloyed Bi_x Se_(1-x) (BSG) thin films by magnetron sputtering methods and have investigated their magneto-transport and spin-torque properties. Structural characterizations show a mainly amorphous feature for the 8nm thick BSG film, while Bi rich crystallites are developed inside the 16nm thick BSG film. The bulk resistivity of BSG film is found to be relatively high, up to 6x10^4 uOhm.cm, with respect to the resistivity of the polycrystalline Bi_x Se_(1-x) film. Temperature dependent resistivity measurements display the evident character of a variable range hopping transport from 80K to 300K. Spin pumping transport characterizations have been performed on the BSG(t)/CoFeB(5 nm) bilayer structures with different thickness of BSG (t= 6, 8, 12, 16 nm). The possible various origins of the spin-to-charge conversion are related to extrinsic effects. Our study provides a new experimental direction, beyond crystalline solids, to the search for strong SOC systems in amorphous solids and other engineered random systems

Bacopa monnieri extract increases rat coronary flow and protects against myocardial ischemia/reperfusion injury

Background: This study explored Bacopa monnieri, a medicinal Ayurvedic herb, as a cardioprotectant against ischemia/reperfusion injury using cardiac function and coronary flow as end-points. Methods: In normal isolated rat hearts, coronary flow, left ventricular developed pressure, heart rate, and functional recovery were measured using the Langendorff preparation. Hearts were perfused with either (i) Krebs-Henseleit (normal) solution, (control), or with 30, 100 μg/ml B. monnieri ethanolic extract (30 min), or (ii) with normal solution or extract for 10 min preceding no-perfusion ischemia (30 min) followed by reperfusion (30 min) with normal solution. Infarct volumes were measured by triphenyltetrazolium staining. L-type Ca2+-currents (ICa, L) were measured by whole-cell patching in HL-1 cells, a mouse atrial cardiomyocyte cell line. Cytotoxicity of B. monnieri was assessed in rat isolated ventricular myocytes by trypan blue exclusion. Results: In normally perfused hearts, B. monnieri increased coronary flow by 63 ± 13% (30 μg/ml) and 216 ± 21% (100 μg/ml), compared to control (5 ± 3%) (n = 8–10, p < 0.001). B. monnieri treatment preceding ischemia/reperfusion improved left ventricular developed pressure by 84 ± 10% (30 μg/ml), 82 ± 10% (100 μg/ml) and 52 ± 6% (control) compared to pre- ischemia/reperfusion. Similarly, functional recovery showed a sustained increase. Moreover, B. monnieri (100 μg/ml) reduced the percentage of infarct size from 51 ± 2% (control) to 25 ± 2% (n = 6-8, p < 0.0001). B. monnieri (100 μg/ml) reduced ICa, L by 63 ± 4% in HL-1 cells. Ventricular myocyte survival decreased at higher concentrations (50–1000 μg/ml) B. monnieri. Conclusions: B. monnieri improves myocardial function following ischemia/reperfusion injury through recovery of coronary blood flow, contractile force and decrease in infarct size. Thus this may lead to a novel cardioprotectant strategy

Nodes of Ranvier and Paranodes in Chronic Acquired Neuropathies

Chronic acquired neuropathies of unknown origin are classified as chronic inflammatory demyelinating polyneuropathies (CIDP) and chronic idiopathic axonal polyneuropathies (CIAP). The diagnosis can be very difficult, although it has important therapeutic implications since CIDP can be improved by immunomodulating treatment. The aim of this study was to examine the possible abnormalities of nodal and paranodal regions in these two types of neuropathies. Longitudinal sections of superficial peroneal nerves were obtained from biopsy material from 12 patients with CIDP and 10 patients with CIAP and studied by immunofluorescence and in some cases electron microscopy. Electron microscopy revealed multiple alterations in the nodal and paranodal regions which predominated in Schwann cells in CIDP and in axons in CIAP. In CIDP paranodin/Caspr immunofluorescence was more widespread than in control nerves, extending along the axon in internodes where it appeared intense. Nodal channels Nav and KCNQ2 were less altered but were also detected in the internodes. In CIAP paranodes, paranodin labeling was irregular and/or decreased. To test the consequences of acquired primary Schwann cells alteration on axonal proteins, we used a mouse model based on induced deletion of the transcription factor Krox-20 gene. In the demyelinated sciatic nerves of these mice we observed alterations similar to those found in CIDP by immunofluorescence, and immunoblotting demonstrated increased levels of paranodin. Finally we examined whether the alterations in paranodin immunoreactivity could have a diagnosis value. In a sample of 16 biopsies, the study of paranodin immunofluorescence by blind evaluators led to correct diagnosis in 70±4% of the cases. This study characterizes for the first time the abnormalities of nodes of Ranvier in CIAP and CIDP, and the altered expression and distribution of nodal and paranodal proteins. Marked differences were observed between CIDP and CIAP and the alterations in paranodin immunofluorescence may be an interesting tool for their differential diagnosis

Meeting the challenges facing wheat production: The strategic research agenda of the Global Wheat Initiative

Wheat occupies a special role in global food security since, in addition to providing 20% of our carbohydrates and protein, almost 25% of the global production is traded internationally. The importance of wheat for food security was recognised by the Chief Agricultural Scientists of the G20 group of countries when they endorsed the establishment of the Wheat Initiative in 2011. The Wheat Initiative was tasked with supporting the wheat research community by facilitating collaboration, information and resource sharing and helping to build the capacity to address challenges facing production in an increasingly variable environment. Many countries invest in wheat research. Innovations in wheat breeding and agronomy have delivered enormous gains over the past few decades, with the average global yield increasing from just over 1 tonne per hectare in the early 1960s to around 3.5 tonnes in the past decade. These gains are threatened by climate change, the rapidly rising financial and environmental costs of fertilizer, and pesticides, combined with declines in water availability for irrigation in many regions. The international wheat research community has worked to identify major opportunities to help ensure that global wheat production can meet demand. The outcomes of these discussions are presented in this paper