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KDP and ADP crystals doped with different concentrations of Fe3+ ions were grown by the "point seed" technique and some KDP crystal samples were annealed. Positron annihilation lifetime spectroscopy and slow positron beam technique were applied to investigate the types and distributions of the defects with different states of charges for KDP and ADP crystals. It was found that the quality of the prismatic sector was better than that of the pyramidal sector, although Fe3+ was mainly enriched in the prismatic sector. The types and content of defects in the pyramidal sector were relatively larger. ADP crystals showed better structural stability, with fewer defects than KDP crystals. This might be one of the reasons for the higher damage threshold of ADP crystals. The results also indicated that thermal annealing could decompose large-size defects into small-size ones to improve KDP crystal quality. However, it could not reduce the influence of Fe3+, such as causing light absorption at 220–300 nm. In addition, the Raman spectroscopy, Fourier-transformed infrared spectroscopy, and ultraviolet absorption spectroscopy were implemented to illustrate the change in the structure and properties after doping in KDP crystals. Notably, this work focused on the types and distributions of microscopic defects, which would be significant for the crystal growth and quality improvement. [ABSTRACT FROM AUTHOR]

Abstract: The complete gene xyn// that encodes endo-1,4-β-xylanase secreted by Aspergillus usamii E001 was cloned and sequenced. The coding region of the gene is separated by only one intron. It encodes 184 amino acid residues of a protein with a calculated molecular weight of 19.8kDa plus a signal peptide of 27 amino acids. The amino acid sequence of the xyn// gene has higher similarity with those of family 11 of glycosyl hydrolases reported from other microorganisms. The mature peptide encoding cDNA was subcloned into pET-28a(+) expression vector. The recombinant plasmid was expressed in Escherichia coli BL21-CodonPlus (DE3)-RIL, and xylanase activity was measured. The expressed fusion protein was analyzed by SDS-PAGE and a new specific band with molecular weight of about 20kDa was found when induced by IPTG. Enzyme activity assay verified the recombinant protein as a xylanase. A maximum activity of 49.6Umg−1 was obtained from cellular extract of E. coli BL21-CodonPlus (DE3)-RIL harboring pET-28a-xyn//. The xylanase had optimal activity at pH 4.6 and 50°C. This is the first report on the cloning of a xylanase gene from A. usamii. [Copyright &y& Elsevier]

Chinese jujube (Ziziphus jujuba Mill.) is a native fruit crop in China. Leaf mottle and dapple fruit disease is prevalent in cultivated jujube plants grown at Aksu in Xinjiang Uygur Autonomous Region of China. Jujube yellow mottle-associated virus (JYMaV), a tentative member in the genus Emaravirus, was recently identified from mottle-diseased jujube plants grown in Liaoning Province in China, but its incidence and genetic diversity in China is unknown. In this study, the genome sequences of three JYMaV isolates from two jujube cultivars and one jujube variant were determined by high-throughput sequencing (HTS) for small RNA and rRNA-depleted RNA coupled with RT-PCR assays. Comparison of these sequences together with sequences of the viral RNA segments derived by primer set 3C/5H-based RT-PCR revealed that genetic diversity was present in the virus populations and high sequence variation occurred at the non-translational regions of each of the viral genomic segments. Field investigation confirmed the close association of the virus with leaf mottle symptoms of jujube plants. Furthermore, this study revealed that P5 encoded in the viral RNA5 displayed a nuclear localization feature differing from the plasmodesma (PD) subcellular localization of the virus movement protein (P4), and the two proteins could interact with each other in the BiFC assays. Our study provides a snapshot of JYMaV genetic diversity in its natural hosts. [ABSTRACT FROM AUTHOR]