Bioflocculation is a promising method of removing GO from the water as it is safe, biodegradable, and non-secondary pollution, but few studies on effective and economic bioflocculant of GO have been reported. Accordingly, this work evaluated flocculation efficiency of an extracellular bioflocculant named MBF-21 produced by Enterococcus faecalis. Optimum culture conditions for bioflocculant production were initial medium pH of 7 and incubation temperature of 40ºC. The optimum carbon and nitrogen sources for bioflocculant production were glucose and beef extract. Results of Fourier transform infrared (FTIR) indicated the presence of carboxyl, hydroxyl, and amide groups on the MBF-21. The Zeta potential of MBF-21 analysis revealed that MBF-21 was mainly negatively charged. MBF-21 showed a significant ability in flocculation of GO, and flocculation efficiency was over 90% under neutral, acidic, and alkaline conditions, indicating that flocculation of GO was ion-independent. The conditions for flocculation of GO were optimized by response surface methodology (RSM) and determined to be an 11.57 mg/L dose and flocculation time of 75 min.
In recent decades the Yinma River Basin has been receiving increasing pollution from industrial and domestic wastewater, agriculture, and livestock production – which are all potential 4-NP pollution sources. Thus, this work investigated spatial-seasonal distribution, risks, and seasonal variations of 4-nonylphenol in the aquatic environment of the Yinma River Basin. The results indicated that the highest concentrations in water and sediment occurred in livestock-production, industrial, and domestic-wastewater areas, and the lowest occurred in agricultural areas; a seasonal variation in 4-NP concentrations in water was observed, with the highest concentrations occurring in the dry season and the lowest concentrations in the wet season. The results for risk quotient indicated that in three water seasons, low ecological risks of 4-NP in water primarily occurred in agricultural areas, and high ecological risks occurred downstream of domestic-wastewater drainage; the ecological risks of 4-NP in sediment from all the sampling sites were exposed to moderate or high ecological risks. Based on the results for hazard quotient, a seasonal variation in human health risks of 4-NP in water was observed; except for a sampling site located downstream of domestic wastewater drainage, human health risks of 4-NP in water were low
High floral abscission ratio in soybean (Glycine max L.) leads to serious yield loss in field culture condition. Ethylene is a phytohormone responsible for the regulation of developmental changes and floral abscission ratio in soybean. It is clear that different phytohormones affected overlapping physiological processes, and the physiological effects of phytohormone depended on specific hormone combination rather than the independent activity of each one. Little is known about how ethylene is integrated into the phytohormone metabolism and signal network. The results of phytohormone content analysis and three RNAseq libraries after silver thiosulfate (STS), ethephon (ETH) and control treatment showed that ethylene biosynthesis and signal pathway was affected by STS treatment according to suppress the mRNA abundance of 1-aminocyclopropane- 1-carboxylate (ACC) syntheses genes, while the ETH treatment induced both ethylene biosynthesis and signal pathway components in soybean. A number of genes involved in IAA, GA, CTK and ABA pathways components were activated or depressed correspondingly. The analysis of transcription factors (TFs) in differential transcriptome profiling and TFs prediction of the differentially transcription genes related to all phytohormone biosynthesis showed that TFs MYB played pivotal roles in the process of ethylene interplaying the whole phytohormones metabolism and signal network.
To shed light on the relationship between sucrose metabolism and expression of genes related to sucrose-metabolizing enzymes, six genes encoding sucrose-metabolizing enzymes were isolated, and the levels of four main carbohydrates and related enzyme activities as well as the expression of these six genes were determined in fruits, leaves and phloem-enriched fraction throughout peach fruit development. Sucrose content in mature fruit ranked first followed by glucose, fructose and sorbitol in that order, while sorbitol was the highest and sucrose lowest in phloem-enriched fraction and leaves. Glucose and fructose had similar change patterns throughout fruit development. Cloning results reveal that the nucleotide sequences of the six genes have high similarity to corresponding genes isolated from other plants. In addition, the expression of these genes and the levels of related enzyme activities varied with tissue and stage of fruit development, suggesting a complexity in relationships between carbohydrates, enzymes activities and related gene expression. Sucrose phosphate synthase maybe a key enzyme involved in sucrose synthesis while sucrose synthase may mainly be responsible for sucrose synthesis in peach fruits at later stages of development. Further studies are needed to genetically and physiologically characterize these genes and enzymes in peach and to gain a better understanding of their functions and relationship with carbohydrate metabolism.
Potassium (K+) is an essential macronutrient for plant growth, development, and fruit quality and yield. K+ uptake and transport is facilitated by KT/HAK/KUP transporters. However, studies to establish molecular mechanisms are rare in fruits, especially in peaches. In this study, we isolated 16 putative KT/HAK/KUP transporter genes in peach, and analyzed K+ homeostasis status in relation to KUP (K+ uptake) gene expression during whole fruit development life. The ‘Xiahui6’ peach development was divided into four distinct stages, S1–S4, and fruits were harvested on 110 days after full bloom (DAFB). QRTPCR results showed that PpeKUP genes unevenly existed in various fruit parts and are differentially expressed during fruit development, ripening, and postharvest storage. The most highest-expressed gene was PpeKUP1 in mesocarp and PpeKUP2 in skin, especially during early stages, while PpeKUP3 was steadily expressed even until postharvest shelf-life. After harvest, the flesh firmness was nonsignificantly changed under cold treatment (4 C), to avoid ripening. Notably, five PpeKUP genes were responsive to cold treatment as their expression were mainly induced in skin, except for PpeKUP3 that was decreased in both mesocarp and skin. Moreover, functional determination showed that PpeKUP1 and PpeKUP2 are important K+ transporters that mediate K+ uptake and accumulation, especially during fruit formation and fast growth stages. This study reveals a close relationship among peach growth, firmness maintenance, and K+ homeostasis, and directly provides potential candidate genes for further molecular studies.
Sucrose synthase (SUS) has been suggested to play a key role in plant sucrose metabolism with recent studies reporting that a small number of genes encoding different isozymes of Sus exist in most plant species. Despite this, information on genes encoding different isozymes of Sus in peach (Prunus persica) is scanty. In this study, we report the prediction, isolation, structural characteristics, phylogenetic connections and expression outline of six Sus genes in peach (PpSus1 to 6). The six PpSus genes were found distributed across scaffolds 1, 3, 5, 7, and 8. Analysis of the exons/introns revealed that PpSus genes contain multiple introns that range from 11 to 13 and displayed a high degree of conservation with corresponding Sus genes in other plant species. The comparative screening of motifs in PpSus proteins indicated high conservation in terms of number, width and order of motifs among PpSus proteins, which indirectly indicates that the six PpSus proteins are indeed members of the SUS family. Phylogenetic analysis revealed that PpSus2 to PpSus4 belonged to group II of the Sus family, PpSus5 and PpSus6 were clustered into group III, and group I contained only one peach gene (PpSus1) together with members from 10 other plant species. Analysis of expression levels of the six PpSus genes revealed that transcripts of PpSus1 were almost undetectable in leaves and in older phloem, while PpSus2 and PpSus4 were almost undetectable in flowers. The other three PpSus genes appeared differentially expressed in all tissues examined and were detected at different stages of tissue development. The results obtained from this study will be useful in selecting candidate PpSus genes for further functional analysis in the pathway of sucrose metabolism in peach and specifically in characterizing the knockout/knockdown mutants of PpSus genes.
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The different methyl metabolic products of inorganic arsenic lead to various toxicities. Arsenic has been demonstrated to induce hepatotoxicity by oxidative stress. The relationship between hepatic injury and inorganic methylation is not yet known. This study was designed to explore the relationship between arsenic methylation and liver oxidative stress induced by arsenic trioxide (ATO). Forty healthy KM mice were randomly divided into control group (0.9% saline) and As₂O₃ (1.0 mg/Kg/day, 2.0 mg/Kg/day, 4.0 mg/Kg/day) groups with gastric perfusion for five weeks using high-efficiency liquid chromatography and hydride genesis atomic fluorescence spectroscopy (HPLC-HGAFS). The products of arsenic trioxiode methylating, including trivalent inorganic arsenic (iAs³⁺), pentavalent inorganic arsenic (iAs⁵⁺), mono methyl arsenic (MMA), and dimethyl arsenic (DMA) in the liver were determined. The indexes of arsenic methylation, including primary methyl index (PMI) and second methyl index (SMI) were calculated. The level of hepatic function and activity of MDA, GSH, SOD, and TAOC were detected with kits. We found that the remaining arsenic metabolic products in liver significantly increased with the increasing doses of arsenic trioxide and the liver function and oxidative stress deteriorated. Negative correlations were found between MMA%, PMI and GSH, SOD, and TAOC, while DMA% and SMI positively correlated with the levels of ALT and AST. PMI and SMI negatively correlated with TAOC, GSH, SOD, ALT, and AST, positively linked with the level of MDA. The present study demonstrates that the hepatotoxicity induced by the arsenic accounts for deteriorating oxidative injury activized by arsenic methylation metabolism, providing additional evidence to suggest a mechanism of arsenic poisoning. Therefore, reducing the process of arsenic methylation may be potentially benefical in treating and – more importantly – preventing arseniasis.
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