Distribution and metabolism of ascorbic acid in pear fruits (Pyrus pyrifolia Nakai cv. Aikansui)

Ascorbate accumulation levels, distribution and key enzyme activities involved in synthesizing via Smirnoff-Wheeler pathway and recycling in different pear fruit tissues during development were studied. Results show that the ascorbate contents increased with the fruit development, and reached the highest titers in 30 days after anthesis (DAA), then decreased and maintained a level. The higher contents of ascorbate in the peel of pear fruit were observed, which results from a combination of higher activities of L-galactose dehydrogenase (GalDH) and L-galactono-1,4-lactone (GalLDH) involving ascorbate biosynthesis and higher dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activities used to recycle ascorbate. Exogenous feeding of ascorbate synthesis precursors demonstrated that the peel had stronger capability of de novo ascorbate biosynthesis via Smirnoff-Wheeler pathway and uronic acid pathway whereas the flesh and core had lower capability for ascorbate synthesis. These results suggest that the pear fruit is able to cause de novo ascorbate biosynthesis and the peel had higher capability for ascorbate biosynthesis than the flesh and core.Keywords: Pyrus pyrifolia, ascorbate, biosynthesisAfrican Journal of Biotechnology Vol. 12(16), pp. 1952-196

Preparation of Copper Oxide/TiO2 Composite Films by Mechanical Ball Milling and Investigated Photocatalytic Activity

The Cu/Ti composite coatings were prepared by the mechanical ball milling, the CuO/TiO2 and Cu2O/TiO2 composite photocatalytic films were obtained by the subsequent oxidation process. The microstructure of the composite films was analyzed by X-ray Diffraction (XRD）and scanning election microscope (SEM). The photocatalytic activity was evaluated, the effects of ball milling time on the formation of the Cu/Ti coatings were investigated, and the effects of the oxidation temperature and oxidation atmosphere on microstructure and photocatalytic activity of the films were studied. The results illustrate that the ball milling time has significant effects on the formation of the coatings and the coatings are continuous and compact by ball milling for 15 h. The photocatalytic activity of the CuO/TiO2 composite films is increased first and then decreased with the oxidation temperature increases, and the photocatalytic activity is the best at 500 °C. The CuO/TiO2 composite films are obtained by the oxidation of Cu/Ti coatings at 500 °C for 15 h in the air, while the Cu2O/TiO2 composite films are oxidized in carbon atmosphere. Photocatalysis efficiency of the films is obviously enhanced with the help of the p-n junction heterostructure in the Cu2O/TiO2 composite films

Inferences from structural comparison: flexibility, secondary structure wobble and sequence alignment optimization

Abstract Background Work on protein structure prediction is very useful in biological research. To evaluate their accuracy, experimental protein structures or their derived data are used as the 'gold standard'. However, as proteins are dynamic molecular machines with structural flexibility such a standard may be unreliable. Results To investigate the influence of the structure flexibility, we analysed 3,652 protein structures of 137 unique sequences from 24 protein families. The results showed that (1) the three-dimensional (3D) protein structures were not rigid: the root-mean-square deviation (RMSD) of the backbone Cα of structures with identical sequences was relatively large, with the average of the maximum RMSD from each of the 137 sequences being 1.06 Å; (2) the derived data of the 3D structure was not constant, e.g. the highest ratio of the secondary structure wobble site was 60.69%, with the sequence alignments from structural comparisons of two proteins in the same family sometimes being completely different. Conclusion Proteins may have several stable conformations and the data derived from resolved structures as a 'gold standard' should be optimized before being utilized as criteria to evaluate the prediction methods, e.g. sequence alignment from structural comparison. Helix/β-sheet transition exists in normal free proteins. The coil ratio of the 3D structure could affect its resolution as determined by X-ray crystallography.</p

An Anti-Cancer Peptide LVTX-8 Inhibits the Proliferation and Migration of Lung Tumor Cells by Regulating Causal Genes’ Expression in p53-Related Pathways

Spider venom has been found to show its anticancer activity in a variety of human malignancies, including lung cancer. In this study, we investigated the anti-cancer peptide toxin LVTX-8, with linear amphipathic alpha-helical conformation, designed and synthesized from the cDNA library of spider Lycosa vittata. Multiple cellular methods, such as CCK-8 assay, flow cytometry, colony formation assay, Transwell invasion and migration assay, were performed to detect peptide-induced cell growth inhibition and anti-metastasis in lung cancer cells. Our results demonstrated that LVTX-8 displayed strong cytotoxicity and anti-metastasis towards lung cancer in vitro. Furthermore, LVTX-8 could suppress the growth and metastasis of lung cancer cells (A549 and H460) in nude mouse models. Transcriptomics, integrated with multiple bioinformatics analysis, suggested that the molecular basis of the LVTX-8-mediated inhibition of cancer cell growth and metastasis manifested in two aspects: Firstly, it could restrain the activity of cancer cell division and migration through the functional pathways, including &ldquo;p53 hypoxia pathway&rdquo; and &ldquo;integrin signaling&rdquo;. Secondly, it could regulate the expression level of apoptotic-related proteins, which may account for programmed apoptosis of cancer cells. Taken together, as an anticancer peptide with high efficiency and acceptable specificity, LVTX-8 may become a potential precursor of a therapeutic agent for lung cancer in the future

Evolution of the Aroma Volatiles of Pear Fruits Supplemented with Fatty Acid Metabolic Precursors

To examine the biochemical metabolism of aroma volatiles derived from fatty acids, pear fruits were incubated in vitro with metabolic precursors of these compounds. Aroma volatiles, especially esters, were significantly increased, both qualitatively and quantitatively, in pear fruits fed on fatty acid metabolic precursors. Cultivars having different flavor characteristics had distinctly different aroma volatile metabolisms. More esters were formed in fruity-flavored “Nanguoli” fruits than in green-flavored “Dangshansuli” fruits fed on the same quantities of linoleic acid and linolenic acid. Hexanal and hexanol were more efficient metabolic intermediates for volatile synthesis than linoleic acid and linolenic acid. Hexyl esters were the predominant esters produced by pear fruits fed on hexanol, and their contents in “Dangshansuli” fruits were higher than in “Nanguoli” fruits. Hexyl esters and hexanoate esters were the primary esters produced in pear fruits fed on hexanal, however the content of hexyl ester in “Dangshansuli” was approximately three times that in “Nanguoli”. The higher contents of hexyl esters in “Dangshansuli” may have resulted from a higher level of hexanol derived from hexanal. In conclusion, the synthesis of aroma volatiles was largely dependent on the metabolic precursors presented

Experimental study of polycyclic aromatic hydrocarbons (PAHs) in n-Heptane laminar diffusion flames from1.0 to 3.0 bar

As PAHs (Polycyclic Aromatic Hydrocarbons) are the main precursor of soot formation during the combustion, the investigation of PAHs formation is essential for the understanding of the soot formation and soot reduction in combustion. In this study, a specially designed burner and the corresponding fueling system was used to stabilize a laminar diffusion flame of n-heptane up to 3.0 bar before it becomes unstable. Using the combination of LII (Laser Induced Incandescence) and LIF (Laser Induced Fluorescence) techniques, the PAHs and soot formation and their distributions in the studied flames were obtained and explained. The results showed that PAHs were almost surrounded by soot and were present in the lower part of the flame. Moreover, the integral soot and PAH intensities exhibited a power law dependence on the pressure, being proportional to pn with n of 1.38 ± 0.32 and 1.49 ± 0.25 respectively under the pressure range of 1.0–3.0 bar

Characterization and Expression Analysis of the UDP Glycosyltransferase Family in Pomegranate (<i>Punica granatum</i> L.)

UDP glycosyltransferases (UGTs) play an indispensable role in regulating signaling pathways and intracellular homeostasis in plants by catalyzing the glycosylation of metabolites. To date, the molecular characteristics and potential biological functions of the UGT gene family in pomegranate (Punica granatum L.) remain elusive. In this study, a total of 120 PgUGT genes were identified in the pomegranate genome. Phylogenetic analysis revealed that these PgUGTs were clustered into 15 groups: 13 conserved groups (A–J and L–N) and two newly discovered groups (P and R). Structural analysis showed that most members in the same evolutionary branch shared similar motifs and gene structures. Gene duplication analysis demonstrated that tandem duplication and fragment duplication were the primary driving force for the expansion of the PgUGT family. Expression analysis based on RNA-seq data indicated that PgUGTs exhibited various expression profiles in different pomegranate tissues. We further analyzed the expression patterns of the PgUGTs of groups E and L in the seed coat of the hard-seeded cultivar ‘Dabenzi’ and the soft-seeded cultivar ‘Tunisia’ at different developmental stages. There were eight PgUGTs with high expression levels in the seed coat of both cultivars: PgUGTE10 was highly expressed in inner and outer seed coats; PgUGTE20, PgUGTE21, PgUGTL6, PgUGTL11, and PgUGTL12 were mainly expressed in the inner seed coat; and PgUGTE12 and PgUGTL13 were mainly expressed in the outer seed coat. Interestingly, the relative expression levels of PgUGTE10 and PgUGTL11 in ‘Tunisia’ were higher than in ‘Dabenzi’. In the seedlings, quantitative real-time PCR analysis showed that the expression level of PgUGTE10 was induced by brassinolide treatment, while the expression of PgUGTL11 was up-regulated both by indole-3-acetic acid and the brassinolide treatment. In addition, the expressions of PgUGTE10 and PgUGTL11 were highly correlated with the expression of genes involved in hormone signaling and lignin biosynthesis pathways. These results suggested that PgUGTE10 and PgUGTL11 are potential candidate genes involved in seed hardness development by catalyzing the glycosylation of specific substrates

Oxidative stress as a key event in 2,6-dichloro-1,4-benzoquinone-induced neurodevelopmental toxicity

2,6-dichloro-1,4-benzoquinone (DCBQ) has been identified as an emerging disinfection byproducts (DBPs) in drinking water and has the potential to induce neurodevelopmental toxicity. However, there is rarely a comprehensive toxicological evaluation of the neurodevelopmental toxicity of DCBQ. Here, neural differentiating SH-SY5Y cells were used as an in vitro model. Our results have found that DCBQ has decreased cell viability and neural differentiation, generated higher level of reactive oxygen species (ROS), increased the percentage of apoptosis and lowered the level of mitochondrial membrane potential, suggesting the neurodevelopmental toxicity of DCBQ. In addition, antioxidant N-acetyl-L-cysteine (NAC) could significantly attenuate these DCBQ-induced neurotoxic effects, supporting our hypothesis that the neurodevelopmental toxicity may be related with oxidative stress induced by DCBQ. We further demonstrated that DCBQ-induced neurodevelopmental toxicity could promote the mitochondrial apoptosis pathway and inhibit the prosurvival PI3K/AKT/mTOR pathway through inducing ROS, which ultimately inhibited cell proliferation and induced apoptosis in neural differentiating SH-SY5Y cells. These findings have provided novel insights into the risk of neurodevelopmental toxic effects associated with DCBQ exposure, emphasizing the importance of assessing the potential neurodevelopmental toxicity of DBPs