Effect of Malondialdehyde Oxidation on Physicochemical Properties and Color Stability of Yak Meat Sarcoplasmic Proteins

Sarcoplasmic proteins (SP) derived from yak meat were oxidized by malondialdehyde (MDA) at different concentrations. The effects of lipid oxidation on physicochemical properties and color stability of SP were investigated by evaluating side-chain amino acid oxidation, protein structure and color of SP and the oxidation status of myoglobin (Mb). The results showed that after MDA oxidation, the a* value, b* value, C* value, and deoxymyoglobin and oxymyoglobin contents of SP significantly decreased (P < 0.05), and the L* value, metmyoglobin content, and ferrylmyoglobin concentration significantly increased (P < 0.05), indicating that MDA oxidation lowered color stability. The contents of carbonyl groups and dimeric tyrosine, the fluorescence intensity of SP-MDA adducts, and the relative contents of β-helix and β-turn significantly increased (P < 0.05), and total sulfhydryl content, surface hydrophobicity, intrinsic fluorescence intensity, and the relative contents of α-helix and random coil significantly declined (P < 0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed blurred expansion of small molecule bands and the formation of macromolecular aggregates, suggesting that MDA promoted the oxidation and aggregation of SP. Pearson correlation analysis revealed significant correlations between MDA oxidation and physicochemical properties and color stability of SP (P < 0.05). This study reveals that MDA alters the structure of SP by directly oxidizing it or mediating Mb oxidation, causing cross-linked aggregation of SP and reducing its color stability

Prediction of spatial distribution characteristics of ecosystem functions based on a minimum data set of functional traits of desert plants

The relationship between plant functional traits and ecosystem function is a hot topic in current ecological research, and community-level traits based on individual plant functional traits play important roles in ecosystem function. In temperate desert ecosystems, which functional trait to use to predict ecosystem function is an important scientific question. In this study, the minimum data sets of functional traits of woody (wMDS) and herbaceous (hMDS) plants were constructed and used to predict the spatial distribution of C, N, and P cycling in ecosystems. The results showed that the wMDS included plant height, specific leaf area, leaf dry weight, leaf water content, diameter at breast height (DBH), leaf width, and leaf thickness, and the hMDS included plant height, specific leaf area, leaf fresh weight, leaf length, and leaf width. The linear regression results based on the cross-validations (FTEIW - L, FTEIA - L, FTEIW - NL, and FTEIA - NL) for the MDS and TDS (total data set) showed that the R2 (coefficients of determination) for wMDS were 0.29, 0.34, 0.75, and 0.57, respectively, and those for hMDS were 0.82, 0.75, 0.76, and 0.68, respectively, proving that the MDSs can replace the TDS in predicting ecosystem function. Then, the MDSs were used to predict the C, N, and P cycling in the ecosystem. The results showed that non-linear models RF and BPNN were able to predict the spatial distributions of C, N and P cycling, and the distributions showed inconsistent patterns between different life forms under moisture restrictions. The C, N, and P cycling showed strong spatial autocorrelation and were mainly influenced by structural factors. Based on the non-linear models, the MDSs can be used to accurately predict the C, N, and P cycling, and the predicted values of woody plant functional traits visualized by regression kriging were closer to the kriging results based on raw values. This study provides a new perspective for exploring the relationship between biodiversity and ecosystem function

Chlorella pyrenoidosa mitigated the negative effect of cylindrospermopsin-producing and non-cylindrospermopsin-producing Raphidiopsis raciborskii on Daphnia magna as a dietary supplement

Feeding effects are crucial for evaluating the capacity of zooplankton to regulate phytoplankton populations within freshwater ecosystems. To examine the impact of the bloom-forming cyanobacteria Raphidiopsis raciborskii, which occurs in tropical and subtropical freshwaters, on the growth of zooplankton Daphnia in relation to toxins, filament length and fatty acid content, we fed D. magna with R. raciborskii only (cylindrospermopsin (CYN)-producing and non-CYN-producing, as the negative controls), Chlorella pyrenoidosa only (as the positive control) and a mixed diet containing R. raciborskii (CYN-producing and non-CYN-producing) and C. pyrenoidosa. Consequently, our findings revealed that the toxic effect of CYN-producing R. raciborskii strains on Daphnia was mitigated by the coexistence of C. pyrenoidosa containing stearidonic acid (SDA, C18:4 ω3) in mixed diets. This was evident in the elevated survival rate compared that from diets containing only R. raciborskii and a significantly higher reproduction and population intrinsic increase rate compared to diets consisting of only R. raciborskii or C. pyrenoidos. Additionally, a strong positive correlation was observed between arachidonic acid (ARA, 20:4ω6) and the population intrinsic increase rate of Daphnia; notably, R. raciborskii strains were found to be rich in the ω6 polyunsaturated fatty acid ARA. These outcomes reinforce the crucial role of polyunsaturated fatty acids in predicting the population increase of crustacean zooplankton, which has long been neglected. Furthermore, our results underscore the potential effectiveness of zooplankton, particularly in temperate lakes, in controlling CYN-producing R. raciborskii populations

Dunhuang Tectonic Belt in northwestern China as a part of the Central Asian Orogenic Belt: Structural and U-Pb geochronological evidence

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.tecto.2018.09.008 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/The Dunhuang Tectonic Belt (DTB) is located about 100 km south of the Beishan–Tianshan orogen in the Central Asian Orogenic Belt in NW China. It was previously considered as a part of the Tarim or North China craton. Detailed structural analyses reveal two episodes of deformation in the central DTB, D1 and D2. D1 is a north-side-up reverse shear, and D2 a dextral strike slip. Mineral assemblages, microstructures and quartz C-axis patterns indicate that D1 deformation took place under amphibolite facies conditions (500 to 600 °C) and D2 mostly under greenschist-facies conditions (300–450 °C). U–Pb zircon dating of eight granitoid/intermediate intrusions (mostly dikes, with well constrained cross-cutting relationships with the D1 and D2 structures) and an amphibolite gneiss indicates that D1 deformation took place before ca. 349 Ma and most likely at ca. 406 Ma, and D2 between ca. 249 Ma and ca. 241 Ma. The DTB has a structural, metamorphic and magmatic signature in the Paleozoic–Mesozoic that is typical of an orogenic belt. It shares a similar geological history with the Beishan–Tianshan orogen and is likely a part of the Central Asian Orogenic Belt. The DTB and the Beishan-Tianshan orogen might represent two separate Paleozoic mountain belts that developed more or less synchronously on the south and north sides, respectively, of the last vestige of the Paleo-Asian Ocean before its terminal closure in the Permian. The D1 reverse shearing in the DTB is interpreted to be related to a Silurian–Devonian terrane accretion/collision and the D2 dextral strike slip to post-accretional/collisional movement among terranes in Late Permian–Middle Triassic time.National Natural Science Foundation of China ["41472166","41272222"]China Geological Survey ["DD20160009"]Natural Sciences and Engineering Research Council of Canad

Duckweed (Lemna minor) as a Model Plant System for the Study of Human Microbial Pathogenesis

BACKGROUND: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. METHODOLOGY/PRINCIPAL FINDINGS: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor) plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS) mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals

Oxidation Behavior of a SPS Sintered ZrB

ZrB2-SiC-MoSi2 ceramic (ZSM) was successfully prepared by SPS sintering process. The micro-structure and mechanical property were characterized, the oxidation behavior of ZSM was mainly studied at 1500 °C in air. Compared to ZrB2-SiC ceramic (ZS), the mechanical property of ZSM was improved significantly. MoB phase increasing the mechanical and chemical bonding force between different phases was formed in ZSM during SPS sintering. After 10 h oxidation at 1500 °C in air, oxide layer thickness of ZSM was thinner than ZS, oxidation resistance of ZSM was better than ZS

Use of 3D faces facilitates facial expression recognition in children

This study assessed whether presenting 3D face stimuli could facilitate children&#39;s facial expression recognition. Seventy-one children aged between 3 and 6 participated in the study. Their task was to judge whether a face presented in each trial showed a happy or fearful expression. Half of the face stimuli were shown with 3D representations, whereas the other half of the images were shown as 2D pictures. We compared expression recognition under these conditions. The results showed that the use of 3D faces improved the speed of facial expression recognition in both boys and girls. Moreover, 3D faces improved boys&#39; recognition accuracy for fearful expressions. Since fear is the most difficult facial expression for children to recognize, the facilitation effect of 3D faces has important practical implications for children with difficulties in facial expression recognition. The potential benefits of 3D representation for other expressions also have implications for developing more realistic assessments of children&#39;s expression recognition.</p

Dual Application: p-CuS/n-ZnS Nanocomposite Construction for High-Efficiency Colorimetric Determination and Photocatalytic Degradation of Tetracycline in Water

Herein, CuS was incorporated with ZnS to form a novel nanocomposite via cation exchange, and the product was then employed for dual application of the colorimetric determination and photocatalytic degradation of tetracycline (TC) in water. The formed p&ndash;n heterojunction provided an improved gap width and electron mobility, which could rapidly catalyze H2O2 to produce plenty of &bull;OH, supporting a color conversion with TMB. Meanwhile, the addition of TC could lead to the further enhancement in colorimetric signal, and the distinction level was sensitive to the target amount. Additionally, under light conditions, the p-CuS/n-ZnS could produce &bull;O2&minus;, &bull;OH, and h+ through photocatalysis, and these ions could degrade the TC via oxidation. In the colorimetric determination of TC, the signal responses were obtained within 10 min, and the detection limit was 20.94 nM. The recovery rates were 99% and 106% for the water samples from Ganjiang river. In the photocatalytic degradation, the TC was degraded by 91% within 120 min, which was threefold that of ZnS. Meanwhile, the morphology feature of the p-CuS/n-ZnS remained after multiple uses, suggesting a favorable material stability. This strategy provides application prospects for the monitoring and control of antibiotics in water