Forces driving transposable element load variation during Arabidopsis range expansion.

Genetic load refers to the accumulated and potentially life-threatening deleterious mutations in populations. Understanding the mechanisms underlying genetic load variation of transposable element (TE) insertion, a major large-effect mutation, during range expansion is an intriguing question in biology. Here, we used 1,115 global natural accessions of Arabidopsis (Arabidopsis thaliana) to study the driving forces of TE load variation during its range expansion. TE load increased with range expansion, especially in the recently established Yangtze River basin population. Effective population size, which explains 62.0% of the variance in TE load, high transposition rate, and selective sweeps contributed to TE accumulation in the expanded populations. We genetically mapped and identified multiple candidate causal genes and TEs, and revealed the genetic architecture of TE load variation. Overall, this study reveals the variation in TE genetic load during Arabidopsis expansion and highlights the causes of TE load variation from the perspectives of both population genetics and quantitative genetics.

Identification of Serum Oxylipins Associated with the Development of Coronary Artery Disease: A Nested Case-Control Study.

Coronary artery disease (CAD) is among the leading causes of death globally. The American Heart Association recommends that people should consume more PUFA-rich plant foods to replace SFA-rich ones to lower serum cholesterol and prevent CAD. However, PUFA may be susceptible to oxidation and generate oxidized products such as oxylipins. In this study, we investigated whether the blood oxylipin profile is associated with the risk of developing CAD and whether including identified oxylipins may improve the predictability of CAD risk. We designed a nested case-control study with 77 cases and 148 matched controls from a 10-year follow-up of the Nutrition and Health Survey in a Taiwanese cohort of 720 people aged 50 to 70. A panel of 46 oxylipins was measured for baseline serum samples. We discovered four oxylipins associated with CAD risk. 13-oxo-ODE, which has been previously found in formed plagues, was positively associated with CAD (OR = 5.02, 95%CI = 0.85 to 15.6). PGE2/PGD2, previously shown to increase cardiac output, was inversely associated (OR = 0.16, 95%CI = 0.06 to 0.42). 15-deoxy-PGJ2, with anti-inflammatory and anti-apoptosis effects on cardiomyocytes (OR = 0.26, 95%CI = 0.09 to 0.76), and 5-HETE, which was associated with inflammation (OR = 0.28, 95%CI = 0.10 to 0.78), were also negatively associated as protective factors. Adding these four oxylipins to the traditional risk prediction model significantly improved CAD prediction.

Self-Assembly Anisotropic Magnetic Nanowire Films Induced by External Magnetic Field.

Self-assembly generated materials induced by an external magnetic field have attracted considerable interest following the development of nanodevices. However, the fabrication of macroscopic and anisotropic magnetic films at the nanoscale remains a challenge. Here, anisotropic magnetic films are successfully prepared using a solution-based nanowire assembly strategy under a magnetic field. The assembly process is manipulated by changing the thickness of silica shell coated on the surface of magnetic nanowires. The anisotropic magnetic films show highly anisotropic magnetization under different angles of magnetic field and better magnetization properties than that of disordered magnetic films. The well-defined nanowire arrays enable magnetization anisotropic property which may be useful in the magnetic energy conversion technologies and biomedical sciences which lie far beyond those achievable with traditional magnetic materials.

Temperature-Invariant Superelastic and Fatigue Resistant Carbon Nanofiber Aerogels.

Superelastic and fatigue-resistant materials that can work over a wide temperature range are highly desired for diverse applications. A morphology-retained and scalable carbonization method is reported to thermally convert a structural biological material (i.e., bacterial cellulose) into graphitic carbon nanofiber aerogel by engineering the pyrolysis chemistry. The prepared carbon aerogel perfectly inherits the hierarchical structures of bacterial cellulose from macroscopic to microscopic scales, resulting in remarkable thermomechanical properties. In particular, it maintains superelasticity without plastic deformation even after 2 × 106 compressive cycles and exhibits exceptional temperature-invariant superelasticity and fatigue resistance over a wide temperature range at least from -100 to 500 °C. This aerogel shows unique advantages over polymeric foams, metallic foams, and ceramic foams in terms of thermomechanical stability and fatigue resistance, with the realization of scalable synthesis and the economic advantage of biological materials.

Transposable elements drive rapid phenotypic variation in Capsella rubella.

Rapid phenotypic changes in traits of adaptive significance are crucial for organisms to thrive in changing environments. How such phenotypic variation is achieved rapidly, despite limited genetic variation in species that experience a genetic bottleneck is unknown. Capsella rubella, an annual and inbreeding forb (Brassicaceae), is a great system for studying this basic question. Its distribution is wider than those of its congeneric species, despite an extreme genetic bottleneck event that severely diminished its genetic variation. Here, we demonstrate that transposable elements (TEs) are an important source of genetic variation that could account for its high phenotypic diversity. TEs are (i) highly enriched in C. rubella compared with its outcrossing sister species Capsella grandiflora, and (ii) 4.2% of polymorphic TEs in C. rubella are associated with variation in the expression levels of their adjacent genes. Furthermore, we show that frequent TE insertions at FLOWERING LOCUS C (FLC) in natural populations of C. rubella could explain 12.5% of the natural variation in flowering time, a key life history trait correlated with fitness and adaptation. In particular, we show that a recent TE insertion at the 3' UTR of FLC affects mRNA stability, which results in reducing its steady-state expression levels, to promote the onset of flowering. Our results highlight that TE insertions can drive rapid phenotypic variation, which could potentially help with adaptation to changing environments in a species with limited standing genetic variation.

Adaptation and Phenotypic Diversification in Arabidopsis through Loss-of-Function Mutations in Protein-Coding Genes.

According to the less-is-more hypothesis, gene loss is an engine for evolutionary change. Loss-of-function (LoF) mutations resulting in the natural knockout of protein-coding genes not only provide information about gene function but also play important roles in adaptation and phenotypic diversification. Although the less-is-more hypothesis was proposed two decades ago, it remains to be explored on a large scale. In this study, we identified 60,819 LoF variants in 1071 Arabidopsis (Arabidopsis thaliana) genomes and found that 34% of Arabidopsis protein-coding genes annotated in the Columbia-0 genome do not have any LoF variants. We found that nucleotide diversity, transposable element density, and gene family size are strongly correlated with the presence of LoF variants. Intriguingly, 0.9% of LoF variants with minor allele frequency larger than 0.5% are associated with climate change. In addition, in the Yangtze River basin population, 1% of genes with LoF mutations were under positive selection, providing important insights into the contribution of LoF mutations to adaptation. In particular, our results demonstrate that LoF mutations shape diverse phenotypic traits. Overall, our results highlight the importance of the LoF variants for the adaptation and phenotypic diversification of plants.

Transposable Elements Contribute to the Adaptation of Arabidopsis thaliana.

Transposable elements (TEs) are mobile genetic elements with very high mutation rates that play important roles in shaping genome architecture and regulating phenotypic variation. However, the extent to which TEs influence the adaptation of organisms in their natural habitats is largely unknown. Here, we scanned 201 representative resequenced genomes from the model plant Arabidopsis thaliana and identified 2,311 polymorphic TEs from noncentromeric regions. We found expansion and contraction of different types of TEs in different A. thaliana populations. More importantly, we identified two TE insertions that are likely candidates to play a role in adaptive evolution. Our results highlight the importance of variations in TEs for the adaptation of plants in general in the context of rapid global climate change.

Adaptation of Arabidopsis thaliana to the Yangtze River basin.

BACKGROUND: Organisms need to adapt to keep pace with a changing environment. Examining recent range expansion aids our understanding of how organisms evolve to overcome environmental constraints. However, how organisms adapt to climate changes is a crucial biological question that is still largely unanswered. The plant Arabidopsis thaliana is an excellent system to study this fundamental question. Its origin is in the Iberian Peninsula and North Africa, but it has spread to the Far East, including the most south-eastern edge of its native habitats, the Yangtze River basin, where the climate is very different. RESULTS: We sequenced 118 A. thaliana strains from the region surrounding the Yangtze River basin. We found that the Yangtze River basin population is a unique population and diverged about 61,409 years ago, with gene flows occurring at two different time points, followed by a population dispersion into the Yangtze River basin in the last few thousands of years. Positive selection analyses revealed that biological regulation processes, such as flowering time, immune and defense response processes could be correlated with the adaptation event. In particular, we found that the flowering time gene SVP has contributed to A. thaliana adaptation to the Yangtze River basin based on genetic mapping. CONCLUSIONS: A. thaliana adapted to the Yangtze River basin habitat by promoting the onset of flowering, a finding that sheds light on how a species can adapt to locales with very different climates.

Long-term balancing selection contributes to adaptation in Arabidopsis and its relatives.

BACKGROUND: In contrast to positive selection, which reduces genetic variation by fixing beneficial alleles, balancing selection maintains genetic variation within a population or species and plays crucial roles in adaptation in diverse organisms. However, which genes, genome-wide, are under balancing selection and the extent to which these genes are involved in adaptation are largely unknown. RESULTS: We performed a genome-wide scan for genes under balancing selection across two plant species, Arabidopsis thaliana and its relative Capsella rubella, which diverged about 8 million generations ago. Among hundreds of genes with shared coding-region polymorphisms, we find evidence for long-term balancing selection in five genes: AT1G35220, AT2G16570, AT4G29360, AT5G38460, and AT5G44000. These genes are involved in the response to biotic and abiotic stress and other fundamental biochemical processes. More intriguingly, for these genes, we detected significant ecological diversification between the two haplotype groups, suggesting that balancing selection has been very important for adaptation. CONCLUSIONS: Our results indicate that beyond the well-known S-locus genes and resistance genes, many loci are under balancing selection. These genes are mostly correlated with resistance to stress or other fundamental functions and likely play a more important role in adaptation to diverse habitats than previously thought.

Ultrathin Tungsten Oxide Nanowires/Reduced Graphene Oxide Composites for Toluene Sensing.

Graphene-based composites have gained great attention in the field of gas sensor fabrication due to their higher surface area with additional functional groups. Decorating one-dimensional (1D) semiconductor nanomaterials on graphene also show potential benefits in gas sensing applications. Here we demonstrate the one-pot and low cost synthesis of W18O49 NWs/rGO composites with different amount of reduced graphene oxide (rGO) which show excellent gas-sensing properties towards toluene and strong dependence on their chemical composition. As compared to pure W18O49 NWs, an improved gas sensing response (2.8 times higher) was achieved in case of W18O49 NWs composite with 0.5 wt. % rGO. Promisingly, this strategy can be extended to prepare other nanowire based composites with excellent gas-sensing performance.

Ultralight Multifunctional Carbon-Based Aerogels by Combining Graphene Oxide and Bacterial Cellulose.

Nanostructured carbon aerogels with outstanding physicochemical properties have exhibited great application potentials in widespread fields and therefore attracted extensive attentions recently. It is still a challenge so far to develop flexible and economical routes to fabricate high-performance nanocarbon aerogels, preferably based on renewable resources. Here, ultralight and multifunctional reduced graphene oxide/carbon nanofiber (RGO/CNF) aerogels are fabricated from graphene oxide and low-cost, industrially produced bacterial cellulose by a three-step process of freeze-casting, freeze-drying, and pyrolysis. The prepared RGO/CNF aerogel possesses a very low apparent density in the range of 0.7-10.2 mg cm-3 and a high porosity up to 99%, as well as a mechanically robust and electrically conductive 3D network structure, which makes it to be an excellent candidate as absorber for oil clean-up and an ideal platform for constructing flexible and stretchable conductors.

Graphene-based macroscopic assemblies and architectures: an emerging material system.

Due to the outstanding physicochemical properties arising from its truly two-dimensional (2D) planar structure with a single-atom thickness, graphene exhibits great potential for use in sensors, catalysts, electrodes, and in biological applications, etc. With further developments in the theoretical understanding and assembly techniques, graphene should enable great changes both in scientific research and practical industrial applications. By the look of development, it is of fundamental and practical significance to translate the novel physical and chemical properties of individual graphene nanosheets into the macroscale by the assembly of graphene building blocks into macroscopic architectures with structural specialities and functional novelties. The combined features of a 2D planar structure and abundant functional groups of graphene oxide (GO) should provide great possibilities for the assembly of GO nanosheets into macroscopic architectures with different macroscaled shapes through various assembly techniques under different bonding interactions. Moreover, macroscopic graphene frameworks can be used as ideal scaffolds for the incorporation of functional materials to offset the shortage of pure graphene in the specific desired functionality. The advantages of light weight, supra-flexibility, large surface area, tough mechanical strength, and high electrical conductivity guarantee graphene-based architectures wide application fields. This critical review mainly addresses recent advances in the design and fabrication of graphene-based macroscopic assemblies and architectures and their potential applications. Herein, we first provide overviews of the functional macroscopic graphene materials from three aspects, i.e., 1D graphene fibers/ribbons, 2D graphene films/papers, 3D network-structured graphene monoliths, and their composite counterparts with either polymers or nano-objects. Then, we present the promising potential applications of graphene-based macroscopic assemblies in the fields of electronic and optoelectronic devices, sensors, electrochemical energy devices, and in water treatment. Last, the personal conclusions and perspectives for this intriguing field are given.

Photothermal poly(N-isopropylacrylamide)/Fe3O4 nanocomposite hydrogel as a movable position heating source under remote control.

Multifunctional nanocomposite hydrogel: swelling-shrink transition of the magnetic sensitive poly(N-isopropylacrylamide)/Fe3O4 (PNIPAM/Fe3O4) nanocomposite hydrogel can be controlled via near-infrared (NIR) laser exposure or non-exposure, which shows potential as a movable position heating source manipulated by combination of an external magnet and near-infrared laser irradiation.

Carbon nanofiber aerogels for emergent cleanup of oil spillage and chemical leakage under harsh conditions.

To address oil spillage and chemical leakage accidents, the development of efficient sorbent materials is of global importance for environment and water source protection. Here we report on a new type of carbon nanofiber (CNF) aerogels as efficient sorbents for oil uptake with high sorption capacity and excellent recyclability. Importantly, the oil uptake ability of the CNF aerogels can be maintained over a wide temperature range, from liquid nitrogen temperature up to ca. 400°C, making them suitable for oil cleanup under harsh conditions. The outstanding sorption performance of CNF aerogels is associated with their unique physical properties, such as low density, high porosity, excellent mechanical stability, high hydrophobicity and superoleophilicity.

In situ controlled synthesis of thermosensitive poly(N-isopropylacrylamide)/Au nanocomposite hydrogels by gamma radiation for catalytic application.

Thermosensitive poly(N-isopropylacrylamide) (PNIPAM)/Au nanoparticle (NP) nanocomposite hydrogels are synthesized by in situ γ-radiation-assisted polymerization of N-isopropylacrylamide monomer aqueous solution in the presence of HAuCl4·4H2O. In this reaction, the PNIPAM hydrogels and the Au NPs are formed simultaneously, thus demonstrating an easy and straightforward synthetic strategy for the preparation of a uniform nanocomposite. The results suggest that increasing the monomer content during the preparation of nanocomposite materials can increase the sizes of Au NPs. The effects of irradiation dose and concentration of HAuCl4·4H2O on the optical and thermal properties of the hydrogel are also investigated. The PNIPAM/Au nanocomposite hydrogels act as an excellent catalyst for the conversion of o-nitroaniline to 1,2-benzenediamine, and the catalytic activity of the composite hydrogel can be tuned by the volume transition of PNIPAM. The in situ polymerization of monomer and reduction of metal ions initiated by a "clean" and "green" γ-radiation technique can be extended to the efficient synthesis of other nanocomposite materials.

Selective synthesis of Zn(1 - x)Mn(x)Se nanobelts and nanotubes from [Zn(1 - x)Mn(x)Se](DETA)0.5 nanbelts in solution (x = 0-0.15) and their EPR and optical properties.

Zn(1 - x)Mn(x)Se (x = 0-0.15) nanobelts and nanotubes can be synthesized via the removal of diethylenetriamine (DETA) in 1-octadecene (ODE) and ethylene glycol (EG), respectively, using [Zn(1 - x)Mn(x)Se](DETA)(0.5) nanobelts as a template. The as-prepared ZnSe nanobelts are single-crystalline and grown along the [001] direction, and the ZnSe nanotubes consist of nanoparticles assembled along the [001] direction. In addition, Mn(2+)-doped Zn(1 - x)Mn(x)Se (x = 0.05, 0.10, 0.15) nanotubes are prepared for the first time if doped [Zn(1 - x)Mn(x)Se](DETA)(0.5) nanobelts are used as the template. The formation process of Zn(1 - x)Mn(x)Se nanobelts and nanotubes has been studied, and a plausible mechanism is proposed. Photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra of Zn(1 - x)Mn(x)Se nanobelts and Zn(1 - x)Mn(x)Se nanotubes have been investigated.

[Spectroscopic investigation of magnetic field effects on radical reactions induced by laser excitation].

Dynamic spin chemistry, including magnetic field effects (MFE), magnetic isotope effects (MIE), CIDEP and CIDNP, has become a research area. In the present paper, the authors briefly introduced the development history and the spectroscopic research state of magnetic field effects for the radical reactions induced by laser excitation. The possible reasons for magnetic field effects of the radical reactions, theories for the conversion of singlet and triplet states, and mechanisms of magnetic field effects were explained and the recent development state of magnetic field effects for the radical reactions was also introduced to domestic scientists.