Impacts of Road Dust on Small Subarctic Lake Systems

Arctic regions have been experiencing increasing pressures from multiple environmental stressors, most notably rapid climate change and human development. Previous research has demonstrated the impacts of calcareous dust from gravel roads on surrounding vegetation and permafrost, whereas aquatic systems have remained largely unstudied. Here, we explore whether 1) the chronic generation of dust from the 740 km long Dempster Highway has affected water chemistry and diatom assemblages in lakes in the Peel Plateau region of the Northwest Territories, and 2) accelerated regional warming has affected these lakes. A suite of 27 water chemistry variables was assessed from 28 lakes along a 40 m – 26 km distance from the highway. Paleolimnological analyses of biological proxies (diatoms, visible reflectance spectroscopy-derived chlorophyll-a, and an index of chrysophyte scales to diatoms [S:D]) were undertaken on dated sediment cores from two lakes near the highway and one lake situated far from the highway, outside the expected range of dust transport. Conductivity and calcium exhibited a wide range of measurements across our 28 sites; lakes within 1 km of the highway generally exhibited higher ions and related variables than more distant lakes. Analyses of diatom assemblages indicated that the two shallower sites near the highway underwent modest compositional changes over the past approximately 100 years, whereas changes recorded at the farther site were more pronounced. The diatom records, supported by chlorophyll-a and S:D indices, indicated that changes in both the near and far lakes were consistent with warming, with little discernable impact from road dust. Whilst chemical changes associated with the half-century old highway corridor appear clear, they are not yet of sufficient magnitude to elicit a directional biological response in algal assemblages.Les régions de l’Arctique subissent de plus en plus de pressions en provenance d’agresseurs environnementaux, plus particulièrement le changement climatique rapide et le développement humain. Des recherches ont permis de démontrer les incidences de la poussière calcaire émanant des routes en gravier sur la végétation et le pergélisol environnants, mais les systèmes aquatiques ont fait l’objet de très peu d’études. Ici, nous explorons : 1) si la production chronique de poussière par la route de Dempster d’une longueur de 740 km a une influence sur la chimie de l’eau et les assemblages de diatomées dans les lacs de la région du plateau Peel, dans les Territoires du Nord-Ouest; et 2) si le réchauffement régional accéléré a un effet sur ces lacs. Un ensemble de 27 variables de chimie des eaux a été évalué à partir de 28 lacs sur une distance variant entre 40 m et 26 km de la route. Des analyses paléolimnologiques de substituts biologiques (diatomées, chlorophylle-a dérivée de la spectroscopie en réflectance visible (chl-a) et indice d’échelles de chrysophytes à diatomées [S:D]) ont été effectuées sur des carottes de sédiments datées, prélevées dans deux lacs situés près de la route et dans un lac situé loin de la route, à l’extérieur de l’étendue possible du transport de la poussière. Dans les 28 sites, les taux de conductivité et de calcium enregistrés se sont répartis sur une vaste gamme de mesures. De manière générale, les lacs se trouvant à moins d’un kilomètre de distance de la route avaient une plus forte teneur en ions et en variables connexes que les lacs plus éloignés. Les analyses d’assemblages de diatomées ont permis de constater que les deux sites moins profonds à proximité de la route avaient connu des changements de composition modestes au cours des cent dernières années environ, tandis que les changements enregistrés au site plus éloigné étaient plus prononcés. Les enregistrements de diatomées, taux de chl-a et indices S:D à l’appui, ont permis de constater que les changements caractérisant tant les lacs situés à proximité qu’à distance coïncidaient avec le réchauffement, et que l’incidence de la poussière de route était à peine perceptible. Bien que les changements chimiques liés au corridor routier d’un demi-siècle semblent clairs, leur ampleur n’est toujours pas suffisante pour obtenir une réponse biologique directionnelle dans les assemblages d’algues

Testing Logselfsimilarity of Soil Particle Size Distribution: Simulation with Minimum Inputs

Particle size distribution (PSD) greatly influences other soil physical properties. A detailed textural analysis is time-consuming and expensive. Soil texture is commonly reported in terms of mass percentages of a small number of size fractions (typically, clay, silt and sand). A method to simulate the PSD from such a poor description or even from the poorest description, consisting in the mass percentages of only two soil size fractions, would be extremly useful for prediction purposes. The goal of this paper is to simulate soil PSDs from the minimum number of inputs, i.e., two and three textural fraction contents, by using a logselfsimilar model and an iterated function system constructed with these data. High quality data on 171 soils are used. Additionally, the characterization of soil texture by entropy-based parameters provided by the model is tested. Results indicate that the logselfsimilar model may be a useful tool to simulate PSD for the construction of pedotransfer functions related to other soil properties when textural information is limited to moderate textural data

Polymeric nanoparticles for nonviral gene therapy extend brain tumor survival in vivo

Biodegradable polymeric nanoparticles have the potential to be safer alternatives to viruses for gene delivery; however, their use has been limited by poor efficacy in vivo. In this work, we synthesize and characterize polymeric gene delivery nanoparticles and evaluate their efficacy for DNA delivery of herpes simplex virus type I thymidine kinase (HSVtk) combined with the prodrug ganciclovir (GCV) in a malignant glioma model. We investigated polymer structure for gene delivery in two rat glioma cell lines, 9L and F98, to discover nanoparticle formulations more effective than the leading commercial reagent Lipofectamine 2000. The lead polymer structure, poly(1,4-butanediol diacrylate-co-4-amino-1-butanol) end-modified with 1-(3-aminopropyl)-4-methylpiperazine, is a poly(\u3b2-amino ester) (PBAE) and formed nanoparticles with HSVtk DNA that were 138 \ub1 4 nm in size and 13 \ub1 1 mV in zeta potential. These nanoparticles containing HSVtk DNA showed 100% cancer cell killing in vitro in the two glioma cell lines when combined with GCV exposure, while control nanoparticles encoding GFP maintained robust cell viability. For in vivo evaluation, tumor-bearing rats were treated with PBAE/HSVtk infusion via convection-enhanced delivery (CED) in combination with systemic administration of GCV. These treated animals showed a significant benefit in survival (p = 0.0012 vs control). Moreover, following a single CED infusion, labeled PBAE nanoparticles spread completely throughout the tumor. This study highlights a nanomedicine approach that is highly promising for the treatment of malignant glioma

AD51B in Familial Breast Cancer

Common variation on 14q24.1, close to RAD51B, has been associated with breast cancer: rs999737 and rs2588809 with the risk of female breast cancer and rs1314913 with the risk of male breast cancer. The aim of this study was to investigate the role of RAD51B variants in breast cancer predisposition, particularly in the context of familial breast cancer in Finland. We sequenced the coding region of RAD51B in 168 Finnish breast cancer patients from the Helsinki region for identification of possible recurrent founder mutations. In addition, we studied the known rs999737, rs2588809, and rs1314913 SNPs and RAD51B haplotypes in 44,791 breast cancer cases and 43,583 controls from 40 studies participating in the Breast Cancer Association Consortium (BCAC) that were genotyped on a custom chip (iCOGS). We identified one putatively pathogenic missense mutation c.541C>T among the Finnish cancer patients and subsequently genotyped the mutation in additional breast cancer cases (n = 5259) and population controls (n = 3586) from Finland and Belarus. No significant association with breast cancer risk was seen in the meta-analysis of the Finnish datasets or in the large BCAC dataset. The association with previously identified risk variants rs999737, rs2588809, and rs1314913 was replicated among all breast cancer cases and also among familial cases in the BCAC dataset. The most significant association was observed for the haplotype carrying the risk-alleles of all the three SNPs both among all cases (odds ratio (OR): 1.15, 95% confidence interval (CI): 1.11–1.19, P = 8.88 x 10−16) and among familial cases (OR: 1.24, 95% CI: 1.16–1.32, P = 6.19 x 10−11), compared to the haplotype with the respective protective alleles. Our results suggest that loss-of-function mutations in RAD51B are rare, but common variation at the RAD51B region is significantly associated with familial breast cancer risk

Measurements of the γvp→p′π+π- cross section with the CLAS detector for 0.4 GeV2<Q2<1.0 GeV2 and 1.3 GeV<W<1.825 GeV

New results on the single-differential and fully integrated cross sections for the process γvp→p′π+π- are presented. The experimental data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the kinematic region of the reaction invariant mass W from 1.3 to 1.825 GeV and the photon virtuality Q2 from 0.4 to 1.0 GeV2. The cross sections were obtained in narrow Q2 bins (0.05 GeV2) with the smallest statistical uncertainties achieved in double-pion electroproduction experiments to date. The results were found to be in agreement with previously available data where they overlap. A preliminary interpretation of the extracted cross sections, which was based on a phenomenological meson-baryon reaction model, revealed substantial relative contributions from nucleon resonances. The data offer promising prospects to improve knowledge on the Q2 evolution of the electrocouplings of most resonances with masses up to ∼1.8 GeV