Metallothioneins 2 and 3 contribute to the metal-adapted phenotype but are not directly linked to Zn accumulation in the metal hyperaccumulator, Thlaspi caerulescens

To study the role of metallothioneins (MTs) in Zn accumulation, the expression of TcMT2a, TcMT2b, and TcMT3 was analysed in three accessions and 15 F3 families of two inter-accession crosses of the Cd/Zn hyperaccumulator Thlaspi caerulescens, with different degrees of Zn accumulation. The highest expression levels were found in the shoots of a superior metal-accumulating calamine accession from St Laurent le Minier, with >10-fold TcMT3 expression compared with another calamine accession and a non-metallicolous accession. Moreover, F3 sibling lines from the inter-accession crosses that harboured the MT2a or MT3 allele from St Laurent le Minier had higher expression levels. However, there was no co-segregation of TcMT2a or TcMT3 expression and Zn accumulation. To examine the functions of TcMTs in plants, TcMT2a and TcMT3 were ectopically expressed in Arabidopsis. The transformant lines had reduced root length in control medium but not at high metal concentrations, suggesting that the ectopically expressed proteins interfered with the physiological availability of essential metals under limited supply. The Arabidopsis transformant lines did not show increased tolerance to Cd, Cu, or Zn, nor increased Cd or Zn accumulation. Immunohistochemical analysis indicated that in roots, MT2 protein is localized in the epidermis and root hairs of both T. caerulescens and Arabidopsis thaliana. The results suggest that TcMT2a, TcMT2b, and TcMT3 are not primarily involved in Zn accumulation as such. However, the elevated expression levels in the metallicolous accessions suggests that they do contribute to the metal-adapted phenotype, possibly through improving Cu homeostasis at high Zn and Cd body burdens. Alternatively, they might function as hypostatic enhancers of Zn or Cd tolerance

Validation of the TROPOspheric Monitoring Instrument (TROPOMI) surface UV radiation product

The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (S5P) satellite was launched on 13 October 2017 to provide the atmospheric composition for atmosphere and climate research. The S5P is a Sun-synchronous polar-orbiting satellite providing global daily coverage. The TROPOMI swath is 2600 km wide, and the ground resolution for most data products is 7:23:5 km2 (5:63:5 km2 since 6 August 2019) at nadir. The Finnish Meteorological Institute (FMI) is responsible for the development of the TROPOMI UV algorithm and the processing of the TROPOMI surface ultraviolet (UV) radiation product which includes 36 UV parameters in total. Ground-based data from 25 sites located in arctic, subarctic, temperate, equatorial and Antarctic areas were used for validation of the TROPOMI overpass irradiance at 305, 310, 324 and 380 nm, overpass erythemally weighted dose rate/UV index, and erythemally weighted daily dose for the period from 1 January 2018 to 31 August 2019. The validation results showed that for most sites 60 % 80% of TROPOMI data was within 20% of ground-based data for snow-free surface conditions. The median relative differences to ground-based measurements of TROPOMI snow-free surface daily doses were within 10% and 5% at two-Thirds and at half of the sites, respectively. At several sites more than 90% of cloud-free TROPOMI data was within 20% of groundbased measurements. Generally median relative differences between TROPOMI data and ground-based measurements were a little biased towards negative values (i.e. satellite data ground-based measurement), but at high latitudes where non-homogeneous topography and albedo or snow conditions occurred, the negative bias was exceptionally high: from 30% to 65 %. Positive biases of 10 % 15% were also found for mountainous sites due to challenging topography. The TROPOMI surface UV radiation product includes quality flags to detect increased uncertainties in the data due to heterogeneous surface albedo and rough terrain, which can be used to filter the data retrieved under challenging conditions

Surface Doping Quantum Dots with Chemically Active Native Ligands: Controlling Valence without Ligand Exchange

One remaining challenge in the field of colloidal semiconductor nanocrystal quantum dots is learning to control the degree of functionalization or valence per nanocrystal. Current quantum dot surface modification strategies rely heavily on ligand exchange, which consists of replacing the nanocrystal\u27s native ligands with carboxylate- or amine-terminated thiols, usually added in excess. Removing the nanocrystal\u27s native ligands can cause etching and introduce surface defects, thus affecting the nanocrystal\u27s optical properties. More importantly, ligand exchange methods fail to control the extent of surface modification or number of functional groups introduced per nanocrystal. Here, we report a fundamentally new surface ligand modification or doping approach aimed at controlling the degree of functionalization or valence per nanocrystal while retaining the nanocrystal\u27s original colloidal and photostability. We show that surface-doped quantum dots capped with chemically active native ligands can be prepared directly from a mixture of ligands with similar chain lengths. Specifically, vinyl and azide-terminated carboxylic acid ligands survive the high temperatures needed for nanocrystal synthesis. The ratio between chemically active and inactive-terminated ligands is maintained on the nanocrystal surface, allowing to control the extent of surface modification by straightforward organic reactions. Using a combination of optical and structural characterization tools, including IR and 2D NMR, we show that carboxylates bind in a bidentate chelate fashion, forming a single monolayer of ligands that are perpendicular to the nanocrystal surface. Moreover, we show that mixtures of ligands with similar chain lengths homogeneously distribute themselves on the nanocrystal surface. We expect this new surface doping approach will be widely applicable to other nanocrystal compositions and morphologies, as well as to many specific applications in biology and materials science

Molecular Chemistry to the Fore: New Insights into the Fascinating World of Photoactive Colloidal Semiconductor Nanocrystals

Colloidal semiconductor nanocrystals possess unique properties that are unmatched by other chromophores such as organic dyes or transition-metal complexes. These versatile building blocks have generated much scientific interest and found applications in bioimaging, tracking, lighting, lasing, photovoltaics, photocatalysis, thermoelectrics, and spintronics. Despite these advances, important challenges remain, notably how to produce semiconductor nanostructures with predetermined architecture, how to produce metastable semiconductor nanostructures that are hard to isolate by conventional syntheses, and how to control the degree of surface loading or valence per nanocrystal. Molecular chemists are very familiar with these issues and can use their expertise to help solve these challenges. In this Perspective, we present our group\u27s recent work on bottom-up molecular control of nanoscale composition and morphology, low-temperature photochemical routes to semiconductor heterostructures and metastable phases, solar-to-chemical energy conversion with semiconductor-based photocatalysts, and controlled surface modification of colloidal semiconductors that bypasses ligand exchange

Mixed-Monolayer-Protected Au 25

Peer reviewe

Genome-wide physical activity interactions in adiposity. A meta-analysis of 200,452 adults

Physical activity (PA) may modify the genetic effects that give rise to increased risk of obesity. To identify adiposity loci whose effects are modified by PA, we performed genome-wide interaction meta-analyses of BMI and BMI-adjusted waist circumference and waist-hip ratio from up to 200,452 adults of European (n = 180,423) or other ancestry (n = 20,029). We standardized PA by categorizing it into a dichotomous variable where, on average, 23% of participants were categorized as inactive and 77% as physically active. While we replicate the interaction with PA for the strongest known obesity-risk locus in the FTO gene, of which the effect is attenuated by similar to 30% in physically active individuals compared to inactive individuals, we do not identify additional loci that are sensitive to PA. In additional genome-wide meta-analyses adjusting for PA and interaction with PA, we identify 11 novel adiposity loci, suggesting that accounting for PA or other environmental factors that contribute to variation in adiposity may facilitate gene discovery.Peer reviewe

The genetics of blood pressure regulation and its target organs from association studies in 342,415 individuals

To dissect the genetic architecture of blood pressure and assess effects on target-organ damage, we analyzed 128,272 SNPs from targeted and genome-wide arrays in 201,529 individuals of European ancestry and genotypes from an additional 140,886 individuals were used for validation. We identified 66 blood pressure loci, of which 17 were novel and 15 harbored multiple distinct association signals. The 66 index SNPs were enriched for cis-regulatory elements, particularly in vascular endothelial cells, consistent with a primary role in blood pressure control through modulation of vascular tone across multiple tissues. The 66 index SNPs combined in a risk score showed comparable effects in 64,421 individuals of non-European descent. The 66-SNP blood pressure risk score was significantly associated with target-organ damage in multiple tissues, with minor effects in the kidney. Our findings expand current knowledge of blood pressure pathways and highlight tissues beyond the classic renal system in blood pressure regulation