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This study aimed to analyze the spatial distribution of soil organic carbon (SOC) and total nitrogen (STN) in a micro-catchment area comprising farmland and a gully with vegetation restoration (artificial forest and grassland) and their influencing factors. We surveyed a total of 52 topsoil sampling sites to measure the SOC and STN content, as well as topographical factors (elevation, curvature, slope gradient, and aspect), soil properties (bulk density, aggregate distribution, soil texture, and soil moisture), and land use and management. We used traditional statistical and geostatistical methods to analyze the spatial variability of SOC and STN. The results of this study indicate that SOC and STN content varied moderately across the entire micro-catchment area, with greater values in the west (gully head area) than in the east (gully mouth area). Additionally, SOC and STN were significantly positively correlated with soil water content, >2 mm size aggregate fraction, and elevation, but negatively correlated with

Topographical factor is one of the most important factors in understanding the formation mechanism of shallow mass movements on gully slopes on the Loess Plateau, China. However, the sensitivity of shallow mass movements on gully slopes to topography is poorly understood. Here, a series of rainfall simulation experiments was performed to quantitatively explore the influences of slope height (1.0 and 1.5 m) and gradient (60° and 70°) on shallow mass movements on the natural loess slopes on the Loess Plateau. Our research observed shallow mass movement processes on undisturbed slopes by using a Topography Meter and collected data that well reflected the nature of the processes. The conducted study has advantageous over traditional methods that are usually used in laboratory tests of backfilled soil. Results showed that the amount of shallow mass movement increased with increased slope height and gradient. The shallow mass movement rates (i.e., gravity erosion rates) increased by approximately 3–8 times with increased slope height from 1.0 m to 1.5 m, and increased by 148%–525% with increased slope gradient from 60° to 70°. The sensitivity coefficient of slope gradients for shallow mass movements was 2.1 times larger than that of slope heights for the shallow mass movements. Slope heights had the greatest effect on earthflow relative to slide and avalanche, whereas slope gradients had the greatest effect on slide. Our results provided insights into natural hazard susceptibility assessment and control erosion processes.

The temporal-spatial changes in flow hydraulics and energy consumption and their associated soil erosion remain unclear during gully headcut retreat. A simulated scouring experiment was conducted on five headcut plots consisting of upstream area (UA), gully headwall (GH) and gully bed (GB) to elucidate the temporal-spatial changes in flow hydraulic, energy consumption, and soil loss during headcut erosion. The flow velocity at the brink of headcut increased as a power function of time, whereas the jet velocity entry to plunge pool and jet shear stress logarithmically or linearly decreased over time. The jet properties significantly affected by upstream flow discharge. The Reynold number, runoff shear stress, and stream power of UA and GB increased as logarithmic or power functions of time, but the Froude number decreased logarithmically over time. The flow of UA and GB was supercritical and subcritical, respectively, and transformed to turbulent with inflow discharge increased. The Reynold number, shear stress and stream power decreased by 56.0 %, 63.8 % and 55.9 %, respectively, but the Froude number increased by 7.9 % when flow dropped from UA to GB. The accumulated runoff energy consumption of UA, GH and GB positions linearly increased with time, and their proportions of energy consumption are 18.3 %, 77.7 % and 4.0 %, respectively. The soil loss rate of the UA-GH-GB system initially rose and then gradually declined and levelled off. The soil loss of UA and GH decreased logarithmically over time, whereas the GB was mainly characterized by sediment deposition. The proportion of soil loss at UA and GH are 11.5 % and 88.5 %, respectively, of which the proportion of deposited sediment on GB reached 3.8 %. The change in soil loss of UA, GH and GB was significantly affected by flow hydraulic and jet properties. The critical energy consumption initiating soil erosion of UA, GH, and GB are 1.62 J s−1, 5.79 J s−1 and 1.64 J s−1, respectively. These results are helpful to reveal the mechanism of gully headcut erosion and built headcut migration model.

It has been challenging to characterize the lineage relationships among cells in vertebrates, which comprise a great number of cells. Fortunately, recent progress has been made by combining the CRISPR barcoding system with single-cell sequencing technologies to provide an unprecedented opportunity to track lineage at single-cell resolution. However, due to errors and/or dropouts introduced by amplification and sequencing, reconstruction of accurate lineage relationships in complex organisms remains a challenge. Thus, improvements in both experimental design and computational analysis are necessary for lineage inference. In this study, we employed single-cell Lineage tracing On Endogenous Scarring Sites (scLOESS), a lineage recording strategy based on the CRISPR-Cas9 system, to trace cell fate commitments for zebrafish larvae. With rigorous quality control, we demonstrated that lineage commitments of complex organisms could be inferred from a limited number of barcoding sites. Together with cell-type characterization, our method could homogenously recover lineage information. In combination with the cell-type and lineage information, we depicted the development histories for germ layers as well as cell types. Furthermore, when combined with trajectory analysis, our methods could capture and resolve the ongoing lineage commitment events to gain further biological insights into later development and differentiation in complex organisms.

Headcut erosion is usually associated with the consumption and transformation of flow energy that occurs when runoff is used to transport sediment. Therefore, flow energy variations in the headcut erosion process are critical in the loess gully region of the Loess Plateau. The aim of this study was to clarify the effects of the flow discharge and slope gradient on flow energy and the response of the headcut erosion process in the gully region of the Loess Plateau. This study examined the headcut erosion process using slope gradients ranging from 1° to 7° in the upstream catchment area and downstream gully bed and inflow discharges ranging from 3.6 to 7.2 m3·h-1. The results showed that the slope gradient has a significant impact on the potential energy in the upstream catchment area; thus, changes in the slope gradients produced changes in the sediment yield. Moreover, the flow discharge significantly influenced not only the potential energy but also the kinetic energy in the upstream catchment area and downstream gully bed. The kinetic energy at the downstream gully bed was 0.03~0.16 J·s-1 lower than that in the upstream catchment area due to the flow drop at the gully head. Greater energy consumption occurred at the gully head than in the upstream catchment area and downstream gully bed, and the gully head contribution to the flow energy consumption was 44.30~64.29%, which increased with increasing flow discharge and decreasing slope gradient. The influence of the slope gradient on the sediment yield was more significant than that of the flow discharge, and a nonlinear regression equation was developed to estimate sediment the yield. The flow energy consumption was significantly correlated with the sediment yield. These findings could improve our understanding of the flow energy characteristics and headcut evolution process during headcut erosion.

The domination of cariogenic bacteria in dental plaque biofilms is the primary cause of dental caries. In view of this, for the purpose of an effective treatment of dental caries, it is of great importance to inhibit the activity of acidogenic bacteria and promote the remineralization of damaged teeth simultaneously. However, the expensive antibacterial agents and poor mineralization ability of materials limit the practical applications. Biomineralization regulated by non-collagenous proteins (NCPs) gives hints to combine the remineralization ability of NCPs with accessible antibacterial property effectively. In this work, we propose a programmed antibacterial and remineralization strategy for the therapy of dental caries based on zinc-substituted hydroxyapatite/ alendronate-grafted polyacrylic acid hybrid nanoneedles (ZHA@ALN-PAA). This hybrid material dissolves in the acidic caries environment and regulate the pH to nearly neutral (6.5). Abundant calcium/ phosphate ions are supplemented and the ALN-PAA embedded in it has also been released, which assists the biomineralization on tooth defect. It has been revealed that the inhibition ratio of ZHA@ALN-PAA against Streptococcus mutans is the highest (11.25 folds that of HA), which originates from the highest zinc ions released (132.9 mg/L). Besides, the interspace of etched enamel is fully filled with regenerated nanorods and the surface microhardness (SMH) is significantly improved (3.68 folds that of etched enamel) after only 3 days of mineralization in vitro. This strategy developed here is simple and cost-effective, which can be referred to design the effective anti-caries materials applied for clinic treatment and daily oral care.

Fisher’s fundamental theorem of natural selection predicts no additive variance of fitness in a natural population. Consistently, studies in a variety of wild populations show virtually no narrow-sense heritability (h2) for traits important to fitness. However, counterexamples are occasionally reported, calling for a deeper understanding on the evolution of additive variance. In this study, we propose adaptive divergence followed by population admixture as a source of the additive genetic variance of evolutionarily important traits. We experimentally tested the hypothesis by examining a panel of ∼1,000 yeast segregants produced by a hybrid of two yeast strains that experienced adaptive divergence. We measured >400 yeast cell morphological traits and found a strong positive correlation between h2 and evolutionary importance. Because adaptive divergence followed by population admixture could happen constantly, particularly in species with wide geographic distribution and strong migratory capacity (e.g., humans), the finding reconciles the observation of abundant additive variances in evolutionarily important traits with Fisher’s fundamental theorem of natural selection. Importantly, the revealed role of positive selection in promoting rather than depleting additive variance suggests a simple explanation for why additive genetic variance can be dominant in a population despite the ubiquitous between-gene epistasis observed in functional assays.

Bloodstream infections rank among the most serious causes of morbidity and mortality in hospitalized patients, partly due to the long period (up to one week) required for clinical diagnosis. In this work, we have developed a sensitive method to quickly and accurately identify bacteria in human blood samples by combining optimized matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) and efficient immunoaffinity enrichment/separation. A library of bacteria reference mass spectra at different cell numbers was firstly built. Due to a reduced sample spot size, the reference spectra could be obtained from as few as 10 to 10(2) intact bacterial cells. Bacteria in human blood samples were then extracted using antibodies-modified magnetic beads for MS fingerprinting. By comparing the sample spectra with the reference spectra based on a cosine correlation, bacteria with concentrations as low as 500 cells per mL in blood serum and 8000 cells per mL in whole blood were identified. The proposed method was further applied to positive clinical blood cultures (BCs) provided by a local hospital, where Escherichia coli and Staphylococcus aureus were identified. Because of the method's high sensitivity, the BC time required for diagnosis can be greatly reduced. As a proof of concept, whole blood spiked with a low initial concentration (10(2) or 10(3) cells per mL) of bacteria was cultured in commercial BC bottles and analysed by the developed method after different BC times. Bacteria were successfully identified after 4 hours of BC. Therefore, an entire diagnostic process could be accurately accomplished within half a day using the newly developed method, which could facilitate the timely determination of appropriate anti-bacterial therapy and decrease the risk of mortality from bloodstream infections.

Articular cartilage, due to its avascular nature and the low cell density, is hard to regenerate once damaged, thus requiring surgical intervention. Natural cartilage exhibits a complex anisotropic feature with nonlinear and viscoelastic mechanical properties owning to complicated architecture making it attractive to mimic the structure. Here, we demonstrate a three-zone composite hydrogel with superficial, middle and deep zones incorporating into cellulose fabric, cellulose nanofiber and wood cellulose fiber respectively to prepare a stack layout composite hydrogel inspired by cartilage architecture with zone-dependent mechanical properties. The results indicate that the three-zone cellulose reinforced polyethylene glycol-based composite hydrogel demonstrates hydrogel creates native-like articular cartilage with zone-dependent, nonlinear and viscoelastic mechanical properties. The compressive moduli of the superficial, middle and deep zones are 298 kPa, 182 kPa and 9.8 MPa respectively, and the middle zone possess obvious nonlinear features. Furthermore, the highly aligned wood frame channels endow deep zone with nutrition and cell transport behaviors which are beneficial to the process of cartilage regeneration. Therefore, the bio-inspired three-zone composite hydrogel has a promising potential application for cartilage repair.

The effects of vegetation restoration on soil erosion resistance of gully head, along a revegetation age gradient, remain poorly understood. Hence, we collected undisturbed soil samples from a slope farmland and four grasslands with different revegetation ages (3, 10, 18, 25 years) along gully heads. Then, these samples were used to obtain soil detachment rate of gully heads by the hydraulic flume experiment under five unit width flow discharges (2&ndash, 6 m3 h). The results revealed that soil properties were significantly ameliorated and root density obviously increased in response to restoration age. Compared with farmland, soil detachment rate of revegetated gully heads decreased 35.5% to 66.5%, and the sensitivity of soil erosion of the gully heads to concentrated flow decreased with revegetation age. The soil detachment rate of gully heads was significantly related to the soil bulk density, soil disintegration rate, capillary porosity, saturated soil hydraulic conductivity, organic matter content and water stable aggregate. The roots of 0&ndash, 0.5 and 0.5&ndash, 1.0 mm had the highest benefit in reducing soil loss of gully head. After revegetation, soil erodibility of gully heads decreased 31.0% to 78.6%, and critical shear stress was improved by 1.2 to 4.0 times. The soil erodibility and critical shear stress would reach a stable state after an 18-years revegetation age. These results allow us to better evaluate soil vulnerability of gully heads to concentrated flow erosion and the efficiency of revegetation.

Vegetation is widely used for controlling landslides around the world; however, rainfall-induced shallow landslides occur frequently on vegetation-covered slopes on the Chinese Loess Plateau during the rainy season. To probe this phenomenon, we conducted on-site investigations and measurements in the Nanxiaohegou catchment on the Loess Plateau to explore the effects of soil properties and vegetation on shallow loess landslides. Most of the loess landslides on vegetation-covered slopes were small scale with depths ranging from 0.3 m to 1.0 m, corresponding to the topsoil being saturated due to rainfall. Majority of shallow landslides occurred on herbage-covered area, which made up 69% of total landslides. There are significant differences in soil properties between the upper layer (root-soil composite) and the lower layer (loess) of the sliding surface. Our study demonstrated that root plays a leading role in landslide erosion and that the most adverse effect of vegetation on landslides is mainly the increase in soil moisture content in the shallow soil through the root zone creating preferential infiltration flow paths. There are remarkable differences in landslide erosion depths and landslide erosion intensities among different vegetation types. The landslide erosion depth and landslide erosion intensity increased linearly with increasing main root depth, indicating that the vegetation root depth determines the landslide erosion intensity during rainfall. Therefore, the potential implications of vegetation especially the herbage to promote landslide occurrences during rainfall should be given more attention in the future.

Thrombosis remains one of the leading causes of mortality and morbidity in the world. Thrombin is a key enzyme involved in the blood clotting processes, which can be intervened by low concentrations of Hirudin. The C-terminal dodecapeptide of Hirudin was capable of inhibiting thrombosis. This peptide has been partially randomized in this report, and the coding sequences have been expressed in yeast as chimerical peptides for secretion into the culture media. Two other semi-random modules have been processed likewise. The supernatant was subsequently tested for anti-thrombin activities. DNA sequencing indicated that the putative positive clone encoded a single serine residue followed by a stop codon. The Ninhydrin assay of the culture supernatant of the positive clone indicated a high content of amino acid. Electrospray Mass Spectrometry showed a distinct peak at 430.5 when the expression products fromPichia pastoriswere examined, suggesting that the compound may be a dimannosylated serine, as yeast possesses glycosylation at serine residues. The observed effects of α-Mannosidase treatments on the function of yeast induction products are consistent with this assumption. Partial randomization of peptides and proteins may accelerate directed evolution, yielding unprecedented number of variants for functional interrogation and drug development.

A continuous cell line, SYSU-OfHe-C, from larval hemocytes of corn borer, Ostrinia furnacalis was established. With increasing passages, the cells grew increasingly faster, and approximately 45% of the cells were in division at passage 55. The culture was mainly composed of two types of cells, granulocytes and plasmatocytes, which showed different division and proliferation behaviors, but possessed similar phagocytic ability. Its spreading ability was significantly weaker than that of hemocytes from naïve larva; however, it could be promoted by larval plasma. Furthermore, its encapsulation ability was also promoted by larval plasma to form multilayer capsules on Sephadex A-25 beads. Finally, the expression of several immune-related genes was verified after provocation by microbes or Sephadex beads. These results indicated that the cell line possessed immune ability depending on the presence of plasma of naïve larvae and are beneficial to studies of insect cellular systems.

Rill erosion is one of the main forms of soil erosion of the hillslopes on the Loess Plateau of China. Few studies have evaluated the effects of land use on the distribution and morphology of rills under extreme rainstorms. A total of 50 rill survey sites were selected in a typical watershed of the Loess Plateau of China to investigate the rill distribution and morphology of three land uses (fallow land, FL; slope farmland, SF; and annual grassland, AG) under extreme rainstorm conditions (called “7·26” rainstorm). Seven parameters (rill width, rill depth, width-depth ratio, cross-section area, rill density, degree of rill dissection and rill erosion modulus) were used to characterize rill morphology, and the basic soil and vegetation properties (bulk density, particle size distribution, and vegetation coverage) and topographic factors (slope length, gradient, direction) were measured. It was found that rills developed on three land uses, and those with widths ranging from 5 to 20 cm accounted for >80%. Rills developed on FL were deeper than those on SF and AG. Almost all rills on FL had a depth of 5–20 cm (90.3%), while the depth of rills on SF and AG were mainly smaller than 15 cm (91.5% and 91.9%, respectively). In addition to width, rill depth and cross-section area of SF and AG were also significantly less than those of FL. SF and FL had a relatively high width-depth ratio and dissection degree. However, land use had no significant effect on rill density. Crop plantations (SF) and grass restoration (AG) significantly reduced rill erosion modulus (28.70% and 45.07% reduction, respectively). Land use, topography, soil, and vegetation factors significantly affected rill morphology (p = 0.001) based on redundancy analysis (RDA) and can explain 48.0% of the total variability of rill morphology, with slope length, vegetation coverage and slope gradient having the greatest influences. Most of the rill morphological parameters significantly decreased as the vegetation coverage increased but they significantly increased with increasing slope length and slope gradient. This study clearly illustrates the severe rill erosion caused by this rainstorm, and indirectly indicates that crop harvesting (FL) aggravates rill erosion and that revegetation (AG) can effectively contain rill erosion. Therefore, rehabilitation efforts should be focused on revegetation (grassland and/or woodland) on steep slopes to control soil erosion.