Enzymatic Preparation and Processing Properties of DPP-IV Inhibitory Peptides Derived from Wheat Gluten: Effects of Pretreatment Methods and Protease Types.

The choice of appropriate proteases and pretreatment methods significantly influences the preparation of bioactive peptides. This study aimed to investigate the effects of different pretreatment methods on the hydrolytic performance of diverse proteases during the production of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides derived from wheat and their foaming and emulsion properties. Dry heating, aqueous heating, and ultrasound treatment were employed as pretreatments for the protein prior to the enzymatic hydrolysis of wheat gluten. FTIR analysis results indicated that all pretreatment methods altered the secondary structure of the protein; however, the effects of dry heating treatment on the secondary structure content were opposite to those of aqueous heating and ultrasound treatment. Nevertheless, all three methods enhanced the protein solubility and surface hydrophobicity. By using pretreated proteins as substrates, five different types of proteases were employed for DPP-IV inhibitory peptide production. The analysis of the DPP-IV inhibitory activity, degree of hydrolysis, and TCA-soluble peptide content revealed that the specific pretreatments had a promoting or inhibiting effect on DPP-IV inhibitory peptide production depending on the protease used. Furthermore, the pretreatment method and the selected type of protease collectively influenced the foaming and emulsifying properties of the prepared peptides.

First Report of Fusarium Root Rot of Tobacco Caused by Fusarium fujikuroi in Guangdong Province, China.

From March to June 2022, Fusarium tobacco root rot broke out in Shaoguan Guangdong Province, China, affecting approximately 15% of tobacco production fields, with an incidence of 24% to 66%. In the early stage, the lower leaves showed chlorosis, and the roots became black. In the later stage, the leaves became browned and withered, the root cortices were broken and shed, and only a small number of roots were left. Eventually, the entire plant died. Six diseased plant samples (cv. yueyan 97) from Shaoguan (113.8°E, 24.8°N) were collected as test materials. The diseased root tissues (4×4 mm) were surface-sterilized using 75% ethanol for 30 s and 2% NaOCl for 10 min, rinsed 3 times with sterile water and incubated for 4 days on potato dextrose agar (PDA) medium at 25 °C. Fungal colonies were subcultured on fresh PDA, grown for the next 5 d and purified by single-spore separation. Eleven isolates with similar morphological characteristics were obtained. Their colonies were white and fluffy, and the bottoms of the culture plates were pale pink after 5 days of incubation. The macroconidia were slender, slightly curved and measured 18.54~45.85 µm×2.35~3.84 µm (n=50), with 3 to 5 septa. The microconidia were oval or spindle shaped, with one to two cells, and measured 5.56~16.76 µm×2.32~3.86 µm (n=50). Chlamydospores were absent. Such characteristics are typical of the genus Fusarium (Booth C, 1971). The SGF36 isolate was chosen for further molecular analysis. The TEF-1α and ß-tubulin genes (Pedrozo et al.2015) were amplified. Based on a phylogenetic tree (neighbor-joining method and 1,000 bootstrap values) obtained using multiplex alignments of concatenations of these two genes from 18 Fusarium species, SGF36 was grouped into a clade with Fusarium fujikuroi strain 12-1 (MK443268.1/MK443267.1) and F. fujikuroi isolate BJ-1 (MH263736.1/MH263737.1). To further identity the isolate, five additional gene sequences (rDNA-ITS (OP862807.1), RPB2, histone 3, calmodulin, and mitochondrial small subunit) (Pedrozo et al.2015), were subjected to BLAST searches in GenBank, and the results indicated that they were most similar to F. fujikuroi sequences, with sequence identities greater than 99%. The phylogenetic tree obtained using six genes except mitochondrial small subunit gene showed that SGF36 was grouped together with four F. fujikuroi strains to form a single clade. Pathogenicity was determined by the inoculation of wheat grains with fungi in potted tobacco plants. The SGF36 isolate was inoculated onto sterilized wheat grains, which were then incubated at 25 °C for 7 d. Thirty wheat grains with fungi were added to 200 g of sterilized soil, which was then mixed well and placed into pots. One six-leaf-stage tobacco seedling (cv. yueyan 97) was planted in each pot. A total of 20 tobacco seedlings were treated. Another 20 control seedlings were treated with wheat grains without fungi. All seedlings were placed in a greenhouse at 25 °C with 90% relative humidity. After 5 d, the leaves of all inoculated seedlings showed chlorosis, and the roots became discolored. No symptoms were observed in the controls. The fungus was reisolated from symptomatic roots and confirmed to be F. fujikuroi based on the TEF-1α gene sequence. No F. fujikuroi isolates were recovered from control plants. F. fujikuroi was previously reported to be associated with rice bakanae disease (Ram et al., 2018), soybean root rot (Zhao et al., 2020) and cotton seedling wilt (Zhu et al., 2020). To our knowledge, this is the first report of F. fujikuroi causing root wilt on tobacco in China. The identification of the pathogen may help to establish appropriate measures for controlling this disease.

Effect of optimized germination technology on polyphenol content and hypoglycemic activity of mung bean.

The study aimed to investigate the effect of germination conditions on the content of polyphenol extract in mung bean and to further investigate the effect of polyphenol extract in germinated mung bean on diabetic mice. Through single factor experiment and response surface experiment, the effects of soaking temperature, soaking time, germination temperature, germination time and soaking liquid CaCl2 concentration on the polyphenol content of mung bean were analyzed. The optimal germination conditions of mung bean were determined as soaking temperature 25°C, soaking time 11 h, germination temperature 28°C, germination time 3 days and CaCl2 concentration 2 mM. Under these conditions, the content of polyphenol extract in germinated mung bean was 4.878 ± 0.30 mg/g, which was 3.07 times higher than that in ungerminated mung bean. The structure and content of purified polyphenols in germinated mung bean were determined by HPLC-MS/MS. Quinic acid, Quercetin, Rutin, Vitexin, Isovitexin and other substances were identified, and the content of polyphenols was 65.19%. In addition, through the in vivo and in vitro hypoglycemic activity experimental study of germinated mung bean polyphenols extract, the results showed that germinated mung bean polyphenols had an in vitro inhibitory effect on α-glucosidase, IC50 was 44.45 mg/ml. In vitro inhibitory activity was stronger after digestion. Polyphenol extract can significantly reduce blood sugar and improve insulin resistance in Type 2 diabetic mice (T2DM). According to the results, germination treatment is an effective way to increase the content of polyphenols in mung bean, and the polyphenols extract has hypoglycemic activity.

Petunia hybrida is a New Host of Pectobacterium brasiliense Associated with Soft Rot Disease in China.

Petunia hybrida is commonly cultivated for ornamental use in urban parks greening and street embellishment in China. In March 2022, 60% of P. hybrida plants cv. Wave Purple (n≈1800) from an ornamental plant nursery under natural conditions in Tianhe district (N 113°21'21", E 23°9'3.5"), Guangzhou, Guangdong Province, China, were affected with soft rot disease. The distribution of the disease was generally uniform. Infected plants initially exhibit small water-soaked lesions at the base of the stem, which then extended to the leaves. Eventually the diseased plant collapsed and died. Nine diseased plants were collected, and affected tissues cut into small fragments (5 × 5 mm), which were disinfested in 75% ethanol (30 s) and 2% sodium hypochlorite (60 s), followed by three rinses with sterile distilled water. The sterilized sections were macerated in 200 µl sterile water, and streaked on Luria-Bertani (LB) agar medium and incubated at 28°C for 48 h. Single colonies were restreaked three times to obtain purified isolation. Sixteen bacterial strains with similar morphology were isolated, and their colonies were yellowish white, round, and convex with smooth surfaces on LB agar plate. The representative strain BDQ1 was selected for further analyses and the 16S rDNA gene (GenBank Accession ON982467) were amplified using primer pair 27F/1492R, revealed above 99% sequence identity with some Pectobacterium brasiliense isolates (GenBank Accession Nos. CP046380(1421/1422), MN393966(1419/1422), and CP020350(1419/1422)) using BLASTn. A multilocus phylogenetic analysis by neighbor-joining method (1,000 bootstrap values) based on six housekeeping gene sequences of gyrA (GenBank Accession No. ON995454), icdA (ON995455), mdh (ON995456), mtlD (ON995457), proA (ON995458), and rpoS genes (ON995459) (Ma et al. 2007; Waleron et al., 2008). The results of phylogenetic analysis showed BDQ1 strain belong to the P. brasiliense clade. Pathogenicity tests were performed on ten healthy P. hybrida cv. Wave Purple plants by injecting 10 µl of bacterial suspensions of BDQ1 (108 CFU/ml) into the stems; another 10 healthy control plants were injected with 10 µl of sterile water. All plants were grown at 25-30°C and 60% humidity in natural light/dark cycle. After 3 d, all inoculated plants showed soft rot symptoms resembling to those observed in the nursery, while control plants remained healthy. Bacteria were successfully reisolated from the symptomatic tissues and identified to be P. brasiliense by PCR mentioned above. P. brasiliense is considered a very aggressive pathogen, which has been reported in Eurasia and Africa (Oulghazi et al. 2021). To our knowledge, this is the first report of P. brasiliense causing bacterial soft rot on P. hybrida in China. This pathogen may pose threat to P. hybrida production in area with warmand humid climate in China. The current study expands the known host range of P. brasiliense and helped raise attention on controlling pathogen spread.

Nutritional Composition, Efficacy, and Processing of Vigna angularis (Adzuki Bean) for the Human Diet: An Overview.

Adzuki beans are grown in several countries around the world and are widely popular in Asia, where they are often prepared in various food forms. Adzuki beans are rich in starch, and their proteins contain a balanced variety of amino acids with high lysine content, making up for the lack of protein content of cereals in the daily diet. Therefore, the research on adzuki beans and the development of their products have broad prospects for development. The starch, protein, fat, polysaccharide, and polyphenol contents and compositions of adzuki beans vary greatly among different varieties. The processing characteristic components of adzuki beans, such as starch, isolated protein, and heated flavor, are reported with a view to further promote the processing and development of adzuki bean foods. In addition to favorable edibility, the human health benefits of adzuki beans include antioxidant, antibacterial, and anti-inflammatory properties. Furtherly, adzuki beans and extracts have positive effects on the prevention and treatment of diseases, including diabetes, diabetes-induced kidney disease or kidney damage, obesity, and high-fat-induced cognitive decline. This also makes a case for the dual use of adzuki beans for food and medicine and contributes to the promotion of adzuki beans as a healthy, edible legume.

Fabrication of Temperature- and Alcohol-Responsive Photonic Crystal Hydrogel and Its Application for Sustained Drug Release.

Herein, crack-free photonic crystal templates with enhanced color contrast were first demonstrated by the coassembly of polystyrene (PS) microspheres and graphene oxide (GO). Then, photonic crystal hydrogels (PCHs) with quick responses to temperature and alcohol solution concentration changes were fabricated by photopolymerization of monomers in the gaps of the self-assembled colloidal crystal templates. The structural color of the PCHs changed from yellow to blue within 120 s as the temperature rose from 25 to 40 °C, whereas upon a decrease in temperature from 40 to 25 °C, the structural color changed from blue to yellow. The structural color of the PCHs also shows an obvious response with the concentration of alcohol solution ranging from 40 to 100 wt %. The quick responses of the PCHs' structural color to changes in temperature and alcohol solution concentration are attributed to the temperature sensitivity of poly(N-isopropylacrylamide) and preferential adsorption and swelling of the alcohol solution for the polymer chains. Furthermore, moxifloxacin (Mox) was loaded into PCHs by hydrogel swelling and exhibited sustained released by increasing the temperature. The sustained release process was facilely monitored by observing the corresponding color changes in real time. The rapid and visible response offers the fabricated PCHs great potential application prospects in the semiquantitative analysis of alcohol concentration and intelligent drug delivery.

Genomic Comparisons and Phenotypic Diversity of Dickeya zeae Strains Causing Bacterial Soft Rot of Banana in China.

Bacterial soft rot of banana, caused by Dickeya zeae, is spreading rapidly in important banana growing areas in China and seriously threatens banana production. In this study, we sequenced the high-quality complete genomes of three typical banana strains, MS1 (size: 4,831,702-bp; genome coverages: 538x), MS_2014 (size: 4,740,000-bp; genome coverages: 586x) and MS_2018 (size: 4,787,201-bp; genome coverages: 583x), isolated in 2009, 2014, and 2018, respectively. To determine their genomic and phenotypic diversity with respect to their hosts of origin, they were compared with other D. zeae strains, including another representative banana strain MS2 from China. The sequenced strains were similar in utilization of carbon source and chemical substrates, and general genomic features of GC content, and tRNA and rRNA regions. They were also conserved in most virulence determinants, including gene-encoding secretion systems, plant cell wall degrading enzymes, and exopolysaccharides. We further explored their genomic diversity in the predicted genomic islands (GIs). These GIs were rich in integrases and transposases, where some genomic dissimilarity was observed in the flagellar gene cluster and several secondary metabolite gene clusters. Different constituents of core biosynthetic modules were found within the bacteriocin and aryl polyene (APE) pigment gene clusters, and the strains from banana showed different phenotypes with respect to antibiosis effects and colony pigmentation. Additionally, clustered regularly interspaced short palindromic repeat (CRISPR) and prophage elements, such as type I-F and III-A CRISPR arrays and an intact prophage of MS1-P5, contributed to bacterial diversity. Phylogenetic tree analysis and genome-genome nucleotide comparison confirmed the genomic divergence among the strains isolated from banana. Considering these characteristics, MS2 and MS_2014 probably diverged later than MS1, while MS_2018 was different and more similar to foreign strains isolated from other hosts in several characteristics. Strain MS_2018 caused severe symptoms on banana varieties previously considered moderately resistant or moderately susceptible, including varieties of Cavendish (Musa AAA) and Plantain (Musa ABB). Our study of genomic and phenotypic diversity raises public attention to the risk of spreading new pathogenic variants within banana growing regions and supports development of predictive strategies for disease control.

Quality Formation of Adzuki Bean Baked: From Acrylamide to Volatiles under Microwave Heating and Drum Roasting.

Baked adzuki beans are rich in tantalizing odor and nutritional components, such as protein, dietary fiber, vitamin B, and minerals. To analyze the final quality of baked beans, the acrylamide and volatile formation of adzuki beans were investigated under the conditions of microwave baking and drum roasting. The results indicate that the acrylamide formation in baked adzuki beans obeys the exponential growth function during the baking process, where a rapid increase in acrylamide content occurs at a critical temperature and low moisture content. The critical temperature that leads to a sudden increase in acrylamide content is 116.5 °C for the moisture content of 5.6% (w.b.) in microwave baking and 91.6 °C for the moisture content of 6.1% (w.b.) in drum roasting. The microwave-baked adzuki beans had a higher formation of the kinetics of acrylamide than that of drum-roasted beans due to the microwave volumetric heating mode. The acrylamide content in baked adzuki beans had a significant correlation with their color due to the Maillard reaction. A color difference of 11.1 and 3.6 may be introduced to evaluate the starting point of the increase in acrylamide content under microwave baking and drum roasting, respectively. Heating processes, including microwave baking and drum roasting, for adzuki beans generate characteristic volatile compounds such as furan, pyrazine, ketone, alcohols, aldehydes, esters, pyrroles, sulfocompound, phenols, and pyridine. Regarding flavor formation, beans baked via drum roasting showed better flavor quality than microwave-baked beans.

NMCP-2 polysaccharide purified from Morchella conica effectively prevents doxorubicin-induced cardiotoxicity by decreasing cardiomyocyte apoptosis and myocardial oxidative stress.

Doxorubicin (DOX) is an anthracycline antibiotic used in the clinical treatment of cancer, but its use is limited due to its cardiotoxic effects. Therefore, it is necessary to explore natural compounds that are effective in protecting against the cardiotoxicity caused by DOX. Neutral Morchella conica polysaccharides-2 (NMCP-2) is a natural polysaccharide with antioxidant activity that was isolated and purified from Morchella conica in our laboratory's previous study. This study aimed to investigate the possible protective effect of NMCP-2 on DOX-induced cardiotoxicity and the potential underlying mechanisms. The model of DOX-induced H9C2 cells and the model of DOX-induced mice were used in this study. In in vitro studies of H9C2 myocardial cells, NMCP-2 effectively increased the activity of H9C2 cells, reducing the levels of lactate dehydrogenase (LDH). In the mouse model of DOX-induced chronic cardiotoxicity, NMCP-2 significantly reduced the cardiac index, reduced the release of serum cardiac enzymes, and improved the pathology of murine myocardial tissues, thereby alleviating DOX-induced cardiotoxicity. Further mechanism studies showed that pretreatment with NMCP-2 counteracted the oxidative stress induced by DOX, as indicated by increasing superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) activities, and malondialdehyde (MDA) production decreased. In addition, we observed NMCP-2 inhibited the activation of the mitochondrial apoptosis pathway and regulated the disordered expression of Bcl-2 and Bax in the myocardial tissues of DOX-treated mice. These findings indicated that NMCP-2, a natural bioactive compound, could potentially be used as a food supplement to reduce the cardiotoxicity caused by DOX.

Antimicrobial Activity of Natural Plant Compound Carvacrol Against Soft Rot Disease Agent Dickeya zeae.

Dickeya zeae is a globally important bacterial pathogen that has been reported to cause severe soft rot diseases in several essential food crops, including bananas, rice, maize, and potatoes. Carvacrol, a hydrophobic terpene component, is found in aromatic plants of the Labiatae family and various essential oils. However, little work has been done on its antimicrobial potential against D. zeae. This study aimed to evaluate the antimicrobial activity and the functional mechanism of carvacrol against D. zeae. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of carvacrol against D. zeae were 0.1 mg/mL and 0.2 mg/mL, respectively. Carvacrol affected the cell membrane of D. zeae, as revealed by decreased intracellular ATP concentration, nucleic acid leakage, and decreased membrane potential. Scanning electron microscopy (SEM) micrographs confirmed that D. zeae cell membranes were damaged by carvacrol. Furthermore, a significant inhibition of D. zeae swimming motility and biofilm formation was observed following treatments with carvacrol at sub-inhibitory concentrations, indicating a significantly negative effect on these virulence factors. Accordingly, the tissue infection test revealed that carvacrol significantly reduced the pathogenicity of D. zeae. In a pot experiment, inoculated banana seedlings displayed remarkably lesser disease symptoms following treatment with carvacrol, and the control efficiency for banana soft rot was 32.0% at 14 days post-inoculation. To summarize, carvacrol exhibits strong antimicrobial activity against D. zeae and great potential applications in the control of D. zeae-associated crop diseases.

First report of Curvularia gladioli causing leaf spots on Gladiolus gandavensis in China.

Gladiolus (Gladiolus gandavensis Van Houtte) is a perennial plant in the family Iridaceae, which shows sword-shaped leaves and spikes of brilliantly colored irregular flowers arising from corms. It is one of the most important fresh cut flowers and is widely cultivated worldwide, including in China. In September 2020, white pinpoints were first observed on gladiolus leaves in Jiangmen City, Guangdong Province, China. The white spots eventually turned brown. The lesions then developed into oval to circular spots, which were surrounded with an obvious yellow halo. The spots expanded and coalesced, causing leaf blight. These symptoms were observed on approximately 10% of gladiolus plants in fields measuring ca. 70 ha. Symptomatic leaves were sampled from fields, surface sterilized in 75% ethanol for 30 s, submerged in a 2% NaOCl solution for 10 min, and rinsed three times with sterile water. The samples were then cut into pieces (5 × 5 mm) and incubated for 4 d on potato dextrose agar (PDA) at 25°C. A representative fungal colony was subcultured onto new PDA and grown for another 7 d, and its mycelium appeared to be grayish-black and villiform. This strain was named as Cg_TS. Its conidiophores were simple, septate, cylindrical in shape, and moderate brown in color. They occurred singly or in groups. They were straight or slightly flexuous and ranged in size from 57.0 to 80.0 µm × 4.0 to 8.0 µm. Conidia were 3-distoseptate and curved at the third cell from the base. The third cell was swollen to one side and larger than other cells. These conidia ranged in size from 23.5 to 32.0 µm × 11.5 to 16.0 µm. These morphological characteristics were consistent with the description of Curvularia gladioli Boerema & Hamers (Boerema and Hamers 1989). Using primer pair ITS1 and ITS4, PCR was applied to amplify the internal transcribed spacer (ITS) region of rDNA. This sequence (GenBank accession No. MW426196.1) was subjected to BLAST in GenBank, suggesting that it was most similar to C. gladioli sequences, LT631345.1 and HG778987.1, with both of 99.49% of similarity. To fulfill Koch's postulates, healthy two-month-old gladiolus plants were used for pathogenicity testing, and the leaves were wounded by pressing slightly with a pipette tip. Mycelium disks (3 mm diameter) were applied onto wounded leaves of 10 plants. Another 10 healthy plants were inoculated with PDA disks which served as control. Inoculated samples were placed in a greenhouse at 25°C and 90% relative humidity. After 3 d, brown leaf spots appeared on all of pathogen-inoculated leaves. The symptoms were consistent with those initially observed and C. gladioli was re-isolated from the symptomatic tissue. Identification was confirmed by morphological observation and ITS sequencing. Control leaves remained symptomless. The curvularia fungus was firstly reported on gladiolus in Florida in 1947 and spread globally via infected corms (Torre et al. 2015), it was also reported to cause leaf spots on gladiolus in Brazil in 2013 (Torres et al. 2013). Although C. gladioli had been recorded as a Curvularia species occurring in China (Zhang et al. 2006), it was not reported to cause leaf spots on gladiolus in Guangdong Province and elsewhere in China. To our knowledge, this is the first report of Curvularia gladioli causing leaf spots on gladiolus in China. Identification of this pathogen will help develop diagnostic methods for corms and seedlings, and may lead to the development of appropriate chemical management strategies.

Genomic divergence between Dickeya zeae strain EC2 isolated from rice and previously identified strains, suggests a different rice foot rot strain.

Rice foot rot caused by Dickeya zeae is an important bacterial disease of rice worldwide. In this study, we identified a new strain EC2 from rice in Guangdong province, China. This strain differed from the previously identified strain from rice in its biochemical characteristics, pathogenicity, and genomic constituents. To explore genomic discrepancies between EC2 and previously identified strains from rice, a complete genome sequence of EC2 was obtained and used for comparative genomic analyses. The complete genome sequence of EC2 is 4,575,125 bp in length. EC2 was phylogenetically closest to previously identified Dickeya strains from rice, but not within their subgroup. In terms of secretion systems, genomic comparisons revealed that EC2 harbored only type I (T1SS), typeⅡ (T2SS), and type VI (T6SS) secretion systems. The flagella cluster of this strain possessed specific genomic characteristics like other D. zeae strains from Guangdong and from rice; within this locus, the genetic diversity among strains from rice was much lower than that of within strains from non-rice hosts. Unlike other strains from rice, EC2 lost the zeamine cluster, but retained the clustered regularly interspaced short palindromic repeats-1 (CRISPR-1) array. Compared to the other D. zeae strains containing both exopolysaccharide (EPS) and capsular polysaccharide (CPS) clusters, EC2 harbored only the CPS cluster, while the other strains from rice carried only the EPS cluster. Furthermore, we found strain MS1 from banana, carrying both EPS and CPS clusters, produced significantly more EPS than the strains from rice, and exhibited different biofilm-associated phenotypes. Comparative genomics analyses suggest EC2 likely evolved through a pathway different from the other D. zeae strains from rice, producing a new type of rice foot rot pathogen. These findings emphasize the emergence of a new type of D. zeae strain causing rice foot rot, an essential step in the early prevention of this rice bacterial disease.

Distribution of tritium concentration in the 0-25 cm surface soil of cultivated and uncultivated soil around the Qinshan nuclear power plant in China.

In this study, tritiated water (HTO) and organically bound tritium (OBT) activity concentration at different depth soil layers (0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, and 20-25 cm) were measured in uncultivated and cultivated soil samples collected in the vicinity of the Qinshan nuclear power plant (QNPP) in July, September, and December 2018. The concentration difference, the spatial and temporal distribution, the seasonal variation, and the OBT/HTO ratios were investigated. The average ratios of HTO concentration between uncultivated and cultivated soil moisture were 1.20 ± 0.24, 1.39 ± 0.46 and 0.95 ± 0.14 in July, September and December, respectively, the corresponding values for OBT were 1.17 ± 0.31, 1.22 ± 0.49 and 1.08 ± 0.28. In generally, the highest HTO concentration in uncultivated soil was found for the topsoil (0-5 cm) in July and September and for the deeper soil layer (20-25 cm) in December, while for cultivated soil, the highest levels were found for the middle layer soil in July, for the topsoil (0-5 cm) in September, and for the deeper layer soil (20-25 cm) in December. Both soils, the vertical profile distribution of OBT concentration showed no consistent tendency, and there were no significant differences in the HTO and OBT concentrations between different soil layers, except for the highest concentration. Whether uncultivated soil or cultivated soil, HTO activity concentrations showed an apparent spatial distribution and seasonal variability, decreasing with the distance to the release sources and with sampling time, while OBT concentrations showed lower spatial and seasonal variability than HTO. In most cases, the OBT/HTO ratios were less than 1, with average values of 1.01 ± 0.48 and 1.06 ± 0.86 for cultivated soil and cultivated soil samples, respectively. The results of this work suggest that farming may affect tritium behavior in soil, while the spatial and temporal distribution of tritium is only slightly impacted.

Synthesis of a manganese dioxide nanorod-anchored graphene oxide composite for highly sensitive electrochemical sensing of dopamine.

In this research, a novel manganese dioxide nanorod-anchored graphene oxide (MnO2 NRs/GO) composite was synthesized by a simple hydrothermal method for electrochemical sensing application. A highly sensitive electrochemical sensor for dopamine (DA) was constructed by modifying glassy carbon electrode (GCE) with MnO2 NRs/GO. The morphology and performance of the composite material and modified GCEs were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV), respectively. The resultant MnO2 NRs/GO composite has a large electroactive area and shows excellent electrochemical activity toward DA. Under the optimal conditions, the DA sensor shows a linear response in the DA concentration ranges of 0.1 µM-0.08 mM and 0.08-0.41 mM with a low detection limit of 0.027 µM and a high sensitivity of 602.4 µA·mM-1·cm-2. The MnO2 NRs/GO composite provides a promising platform for the construction of a highly sensitive and selective sensor of DA.

Multifunctional cellulose nanocrystal structural colored film with good flexibility and water-resistance.

Chiral nematic cellulose nanocrystal (CNC) structural colored materials are the focus of extensive research in recent years on account of their unique helical structure and excellent optical properties. However, the general weak mechanical properties and poor water-resistance of CNC limit its utility. Here, we fabricated highly flexible, water-resistant chiral nematic CNC/Poly(ethylene glycol) diacrylate(PEGDA) composite films, which was realized by co-assembling CNC and PEGDA precursor then via UV curing to construct a three-dimensional crosslinking network. Due to the water stimulus-responsive feature of the CNC and PEGDA, the CNC/PEGDA (8/2) composite film could be used as a water-content detector, photonic paper. In addition, it could produce different crosslinking degrees by coating the PEGMA solution or not, which could be applied to an anti-counterfeit label. The composite film with excellent stability of cycles is expected to be a promising candidate in optical sensors, display, and security fields.

Facile synthesis of novel reduced graphene oxide@polystyrene nanospheres for sensitive label-free electrochemical immunoassay.

Herein, we report the synthesis of novel nanosized reduced graphene oxide@polystyrene nanospheres (rGO@PS NSs) through an electrostatic interaction method, and further their exploitation for highly sensitive label-free electrochemical immunoassay applications. These rGO@PS NSs provide a universal and promising carrier platform to develop excellent biosensors for clinical screening and diagnostic applications.

Tritiated water (HTO) uptake and loss in maize plant after short-term exposure of atmospheric HTO vapor at daytime and nighttime.

Maize plants were exposed to atmospheric tritiated water (HTO) in the field for 1 h during the day and night under different growth periods. The uptake of HTO vapor by leaves and tissue free water tritium (TFWT) loss in maize plants were investigated. Rate constants of uptake of HTO from the atmosphere by maize leaves were 0.10 ±â€¯0.02-0.21 ±â€¯0.01 h-1 during the daytime exposure and 0.035 ±â€¯0.001-0.13 ±â€¯0.01 h-1 in the nighttime exposure. The uptake rate tended to decrease as the exposure increased and harvest neared. At the end of exposure, the TFWT concentration was highest in the leaf and lowest in the ear, the TFWT concentration in different parts of maize varied by a factor of 3-28 for daytime release and 2-30 for nighttime release. After the end of every exposure, TFWT was lost rapidly from different maize tissues for one day and then at a much slower rate until to harvest. At harvest, the TFWT concentrations varied with different maize tissues by factors of 1-4. The decrease was by factors of 4-351 for daytime exposure and 6-605 for nighttime exposure. The reduction of TFWT varied with the exposure time by the factors of 1-10 depending on plant parts. The reduction factor was lowest in kernel. This result suggests that the HTO vapor uptake rates in maize leaves and TFWT loss rates in the ear may be lower than those in C3 plants.

HTO activity concentrations in soil and plants in the vicinity of Qinshan Nuclear Power Plant Base.

To explore the distributions of tritiated water (HTO) in soil and plants after routine release of tritium, this study focused on the Qinshan Nuclear Power Plant Base(QNPPB) using both soil samples at different depths (0-2 cm, 0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, and 20-25 cm) and vegetation samples (including leaves and grasses) from eight sampling points. Then, HTO activity concentrations were measured in all samples. The results showed that the range in HTO activity concentrations in the leaves was 24-39.5 Bq/L and in the grasses was 27-85.5 Bq/L.HTO activity concentrations in the topsoil sample (0-2 cm) from the Qinshan Phase III were greatest. At a same sampling point, the HTO activity concentration was the greatest in the topsoil sample. In most case, except for the top soil layer, HTO activity concentration in different depth soil layer differed slightly. Overall, the HTO activity concentration in leaves and grasses were lower than that in the soil at the same site, and the ratios of HTO activity concentration in plant to soil were found to vary between 0.38 and 2.1, with a mean value of 0.79. This result suggests that some parameters used in the specific activity model proposed to predict tritium activities provide a conservative estimate for the QNPPB site; it should be revisited to better account for the behavior of HTO in the actual environment.

In Vitro Formation of Dickeya zeae MS1 Biofilm.

Bacterial soft rot caused by Dickeya zeae MS1 (Erwinia chrysanthemi) is one of the most devastating banana diseases worldwide. However, knowledge of the development and ecological interactions of D. zeae MS1 biofilm is limited. Here, we visualized the development and architecture of D. zeae MS1 biofilm using confocal laser scanning microscopy, and we evaluated the ability of D. zeae MS1 to form biofilms under different environmental conditions (carbon sources, temperatures, pH levels and mineral elements) using a microtiter plate assay. We found that the development of D. zeae MS1 biofilm could be categorized into four phases and that mature biofilm consisted of a highly organized architecture of both bacterial cells and a self-produced matrix of extracellular polysaccharides. Furthermore, sucrose was the most suitable carbon source for supporting the growth of biofilm cells and that 32 °C and pH 7.0 were the most favorable of the temperatures and pH levels examined. Meanwhile, the addition of Ca2+, Fe2+, K+ and Na+ enhanced the formation of biofilm in minimal medium cultures, whereas 2.5 mM Cu2+ and Mn2+ was inhibitory. A better understanding of biofilm formation under different environmental parameters will improve our knowledge of the growth kinetics of D. zeae MS1 biofilm.

Genomic analysis of the Phalaenopsis pathogen Dickeya sp. PA1, representing the emerging species Dickeya fangzhongdai.

BACKGROUND: Dickeya sp. strain PA1 is the causal agent of bacterial soft rot in Phalaenopsis, an important indoor orchid in China. PA1 and a few other strains were grouped into a novel species, Dickeya fangzhongdai, and only the orchid-associated strains have been shown to cause soft rot symptoms. METHODS: We constructed the complete PA1 genome sequence and used comparative genomics to explore the differences in genomic features between D. fangzhongdai and other Dickeya species. RESULTS: PA1 has a 4,979,223-bp circular genome with 4269 predicted protein-coding genes. D. fangzhongdai was phylogenetically similar to Dickeya solani and Dickeya dadantii. The type I to type VI secretion systems (T1SS-T6SS), except for the stt-type T2SS, were identified in D. fangzhongdai. The three phylogenetically similar species varied significantly in terms of their T5SSs and T6SSs, as did the different D. fangzhongdai strains. Genomic island (GI) prediction and synteny analysis (compared to D. fangzhongdai strains) of PA1 also indicated the presence of T5SSs and T6SSs in strain-specific regions. Two typical CRISPR arrays were identified in D. fangzhongdai and in most other Dickeya species, except for D. solani. CRISPR-1 was present in all of these Dickeya species, while the presence of CRISPR-2 varied due to species differentiation. A large polyketide/nonribosomal peptide (PK/NRP) cluster, similar to the zeamine biosynthetic gene cluster in Dickeya zeae rice strains, was discovered in D. fangzhongdai and D. solani. The D. fangzhongdai and D. solani strains might recently have acquired this gene cluster by horizontal gene transfer (HGT). CONCLUSIONS: Orchid-associated strains are the typical members of D. fangzhongdai. Genomic analysis of PA1 suggested that this strain presents the genomic characteristics of this novel species. Considering the absence of the stt-type T2SS, the presence of CRISPR loci and the zeamine biosynthetic gene cluster, D. fangzhongdai is likely a transitional form between D. dadantii and D. solani. This is supported by the later acquisition of the zeamine cluster and the loss of CRISPR arrays by D. solani. Comparisons of phylogenetic positions and virulence determinants could be helpful for the effective quarantine and control of this emerging species.