Rational design of monodispersed Au@Pt core-shell nanostructures with excellent peroxidase-mimicking activity for colorimetric detection of Cr(VI).

Cr(VI) is one of the most typical heavy metal contaminants and rapid detection of Cr(VI) is highly important in food control and public health. Herein, a core-shell Au@Pt nanozyme-based colorimetric assay was developed for the rapid and sensitive detection of Cr(VI). The monodispersed Au@Pt core-shell nanoparticles exhibited high peroxidase-mimicking activity and can catalyze colorless TMB into blue-colored oxidized oxTMB. After the addition of Cr(VI), the oxTMB molecules can be reduced into colorless TMB. The ultrathin Pt shell can prevent the Pt component from aggregation, thus improving the catalytic activity of Au@Pt nanozyme. These Au@Pt nanozyme-based Cr(VI) assays exhibited high sensitivity and selectivity and displayed satisfactory recoveries in practical samples. Our work highlights opportunities for the development of core-shell nanozymes with extensive applications in food safety, biomedicine, and environmental monitoring.

Preparation of a hydrophobic deep eutectic solvent and its application in the detection of quinolone residues in cattle urine.

Enrichment for the detection of quinolone residues is usually cumbersome and requires large amounts of toxic organic reagents. Therefore, this study synthesized a low-toxicity hydrophobic deep eutectic solvent (DES) with DL-menthol and p-cresol, which was then characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermal analysis. A simple and rapid vortex-assisted liquid-liquid microextraction method was developed based on this DES for the extraction of eight quinolones from cattle urine. The optimal extraction conditions were screened by examining the DES volume, extraction temperature, vortex time, and salt concentration. Under the optimal conditions, the linear ranges of the eight quinolones were 1 ~ 100 µg/L with good linearity (r2 was 0.998 ~ 0.999), and the limits of detection and quantification were 0.08 ~ 0.30 µg/L and 0.27 ~ 0.98 µg/L, respectively. The average extraction recoveries of spiked cattle urine samples were 70.13 ~ 98.50% with relative standard deviations below 13.97%. This method can provide a reference for the pre-treatment of quinolone residue detection.

Transcriptome analysis of gene expression in the tomato leaf premature senescence mutant.

Premature senescence of leaves can critically influence tomato yield and quality. In this study, the leaf premature senescence mutant MT318 was a spontaneous mutant and was controlled by a single recessive nuclear gene. The maximum photochemical efficiency (Fv/Fm), superoxide dismutase (SOD), and chlorophyll content in the leaves of mutant MT318 gradually decreased, while malondialdehyde (MDA) content significantly increased. Under the level 2 category, Gene Ontology (GO) enrichment analysis indicated that 45 terms were enriched, comprising 22 in biological process, 12 in cellular component, and 11 in molecular function. Genes are mainly involved in the metabolic processes (696 differentially expressed genes, DEGs), cellular processes (573 DEGs), single-organism processes (503 DEGs), and catalytic activity (675 DEGs). Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated that the 4 pathways with the largest number of genes were biosynthesis of secondary metabolites, plant-pathogen interaction, plant hormone signal transduction, and MAPK signaling pathway-plant. The 'plant hormone signal transduction' pathway was the most significantly enriched at the T2 stage. Pearson correlation analysis showed that the auxin regulatory pathway and SA signal transduction pathway may play important roles. These results not only lay the foundation for the further cloning and functional analysis of the MT318 premature senescence gene but also provide a reference for the study of tomato leaf senescence. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01223-2.

Effects of vegetation and climate on the changes of soil erosion in the Loess Plateau of China.

Soil erosion is simultaneously driven by multiple factors. Identifying the dominant controlling factors and quantifying the contribution of each factor would be helpful to sustain water and soil resources. China's Loess Plateau was taken as an example area to investigate the above issues since it is the most eroded region in the world, and its soil loss is being controlled by a large-scale revegetation program. We extended the Revised Universal Soil Loss Equation (RUSLE) to large-scale erosion estimation with the aid of GIS for the period of 1986-2015, analyzed the relationship between erosion and controlling factors by correlation and wavelet coherence analysis, and quantified the contribution of each factor to erosion change by the elasticity coefficient method. Results showed that the soil erosion decreased from 1013 t·km-2·a-1 in 1991-1995 to 595 t·km-2·a-1 in 2011-2015, with a downward trend in the whole period. Spatially, most areas had soil erosion of slight intensity, and the areas with high-intensity erosion concentrated in a northeast-southwest strip with hilly-gully landscapes or densely distributed rivers. The changes in surface conditions including vegetation cover and soil conservation measures had dominant effects on the spatial heterogeneity of erosion, their contribution to erosion reduction was 119%. But rainfall erosivity increased soil erosion, and it had a contribution to erosion reduction of -28%. These results are helpful in understanding the mechanism behind the changes in soil erosion and providing information for sustainable soil and water management and vegetation restoration.

Runoff change controlled by combined effects of multiple environmental factors in a headwater catchment with cold and arid climate in northwest China.

The limited runoff in cold and arid regions is sensitive to environmental changes, and it is thus urgent to explore the change and controlling factors of runoff under the background of global warming and intensified human activities. However, previous studies have rarely considered the combined effects of multiple controlling factors at varying scales over time. With the headwater region of the Manas River in northwest China as the study area, we investigated the change in runoff for the period of 1954-2016 and its relationship with regional environmental factors (e.g. precipitation PCP, temperature TMP, potential evapotranspiration ET0, snow cover extent SCE, land use, and normalized difference vegetation index NDVI) and/or global atmospheric circulation (e.g. North Atlantic Oscillation NAO, Arctic Oscillation AO, Pacific Interdecadal Oscillation PDO, and El Nino Southern Oscillation ENSO). In particular, the combined effects of multiple environmental factors were determined at different scales by the multiple wavelet coherence. The annual runoff significantly increased at a rate of 0.508 × 108 m3/decade, and the climate tended to be warmer and wetter. Among the regional and global environmental factors, NDVI and ENSO were the single factor mostly correlated with runoff, while NDVI-TMP and ENSO-PDO were the combined factors with the stronger relations on runoff, respectively. The regional environmental factors had larger impacts on runoff than the global environmental factors, and the natural factors outperformed human activities in controlling runoff. The accelerated melting of snow/glacier induced by the increasing temperature dominated runoff change, and the increasing water inputs from wetter climate may play a second role in runoff. The runoff characteristics in cold and arid regions seem to be different from those regions with little snow/glacier, which should be paid more attention. The employed multiple wavelet coherence is helpful in determining the processes dominating runoff change.

Target Specificity of the CRISPR-Cas9 System in Arabidopsis thaliana, Oryza sativa, and Glycine max Genomes.

Clustered regularly interspaced short palindromic repeats (CRISPR), a class of immune-associated sequences in bacteria, have been developed as a powerful tool for editing eukaryotic genomes in diverse cells and organisms in recent years. The CRISPR-Cas9 system can recognize upstream 20 nucleotides (guide sequence) adjacent to the protospacer-adjacent motif site and trigger double-stranded DNA cleavage as well as DNA repair mechanisms, which eventually result in knockout, knockin, or site-specific mutagenesis. However, off-target effect caused by guide sequence misrecognition is the major drawback and restricts its widespread application. In this study, global analysis of specificities of all guide sequences in Arabidopsis thaliana, Oryza sativa (rice), and Glycine max (soybean) were performed. As a result, a simple pipeline and three genome-wide databases were established and shared for the scientific society. For each target site of CRISPR-Cas9, specificity score and off-target number were calculated and evaluated. The mean values of off-target numbers for A. thaliana, rice, and soybean were determined as 27.5, 57.3, and 174.7, respectively. Comparative analysis among these plants suggested that the frequency of off-target effects was correlated to genome size, chromosomal locus, gene density, and guanine-cytosine (GC) content. Our results contributed to the better understanding of CRISPR-Cas9 system in plants and would help to minimize the off-target effect during its applications in the future.

Evolutionary Conservation and Expression Patterns of Neutral/Alkaline Invertases in Solanum.

The invertase gene family in plants is composed of two subfamilies of enzymes, namely, acid- and neutral/alkaline invertases (cytosolic invertase, CIN). Both can irreversibly cleave sucrose into fructose and glucose, which are thought to play key roles in carbon metabolism and plant growth. CINs are widely found in plants, but little is reported about this family. In this paper, a comparative genomic approach was used to analyze the CIN gene family in Solanum, including Solanumtuberosum, Solanumlycopersicum, Solanumpennellii, Solanumpimpinellifolium, and Solanummelongena. A total of 40 CINs were identified in five Solanum plants, and sequence features, phylogenetic relationships, motif compositions, gene structure, collinear relationship, and expression profile were further analyzed. Sequence analysis revealed a remarkable conservation of CINs in sequence length, gene number, and molecular weight. The previously verified four amino acid residues (D188, E414, Arg430, and Ser547) were also observed in 39 out of 40 CINs in our study, showing to be deeply conserved. The CIN gene family could be distinguished into groups α and ß, and α is further subdivided into subgroups α1 and α2 in our phylogenetic tree. More remarkably, each species has an average of four CINs in the α and ß groups. Marked interspecies conservation and collinearity of CINs were also further revealed by chromosome mapping. Exon-intron configuration and conserved motifs were consistent in each of these α and ß groups on the basis of in silico analysis. Expression analysis indicated that CINs were constitutively expressed and share similar expression profiles in all tested samples from S. tuberosum and S.lycopersicum. In addition, in CIN genes of the tomato and potato in response to abiotic and biotic stresses, phytohormones also performed. Overall, CINs in Solanum were encoded by a small and highly conserved gene family, possibly reflecting structural and functional conservation in Solanum. These results lay the foundation for further expounding the functional characterization of CIN genes and are also significant for understanding the evolutionary profiling of the CIN gene family in Solanum.