Burkholderia sp. SCMS54 reduces cadmium toxicity and promotes growth in tomato

Cadmium (Cd) can enter soil through the use of fertilisers, calcareous, pesticides and industrial and/or domestic effluents. Cd can leach into groundwater and be taken up by plants, potentially leading to reductions in plant growth and yield. In soil, plant roots interact with heavy metal (HM)‐tolerant microorganisms that may promote plant growth. Soil microorganisms may also be able to solubilise or mobilise soil metals, thereby acting as bioremediators. A better understanding of the interaction among plants, metals, microorganisms and soil will lead to improved plant tolerance. Two multi‐tolerant bacteria from the Burkholderia genus were isolated from Cd‐contaminated and Cd‐uncontaminated soil of a coffee plantation. In addition to its high tolerance to Cd, the strain SCMS54 produces indole‐acetic acid (IAA), solubilises inorganic phosphate and produces siderophores, demonstrating its potential to contribute to beneficial plant–microorganism interactions. When interacting with tomato plants exposed to Cd, the bacterium led to decreases in plant peroxide and chlorosis levels, promoted relative plant growth and decreased the root absorption of Cd, resulting in increased plant tolerance to this highly toxic HM. The results indicated that the inoculation of tomato plants with Burkholderia sp. SCMS54 promotes better growth in plants cultivated in the presence of Cd. This phenomenon appears to be attributed to a mechanism that decreases Cd concentrations in the roots via a beneficial interaction between the bacteria and the plant roots.     

Defining the Epigenetic Mechanism of Asymmetric Cell Division of Schizosaccharomyces japonicus Yeast

A key question in developmental biology addresses the mechanism of asymmetric cell division. Asymmetry is crucial for generating cellular diversity required for development in multicellular organisms. As one of the potential mechanisms, chromosomally borne epigenetic difference between sister cells that changes mating/cell type has been demonstrated only in the Schizosaccharomyces pombe fission yeast. For technical reasons, it is nearly impossible to determine the existence of such a mechanism operating during embryonic development of multicellular organisms. Our work addresses whether such an epigenetic mechanism causes asymmetric cell division in the recently sequenced fission yeast, S. japonicus (with 36% GC content), which is highly diverged from the well-studied S. pombe species (with 44% GC content). We find that the genomic location and DNA sequences of the mating-type loci of S. japonicus differ vastly from those of the S. pombe species. Remarkably however, similar to S. pombe, the S. japonicus cells switch cell/mating type after undergoing two consecutive cycles of asymmetric cell divisions: only one among four “granddaughter” cells switches. The DNA-strand–specific epigenetic imprint at the mating-type locus1 initiates the recombination event, which is required for cellular differentiation. Therefore the S. pombe and S. japonicus mating systems provide the first two examples in which the intrinsic chirality of double helical structure of DNA forms the primary determinant of asymmetric cell division. Our results show that this unique strand-specific imprinting/segregation epigenetic mechanism for asymmetric cell division is evolutionary conserved. Motivated by these findings, we speculate that DNA-strand–specific epigenetic mechanisms might have evolved to dictate asymmetric cell division in diploid, higher eukaryotes as well.     

杜仲主要生物活性研究进展

杜仲作为传统滋补药材引起人们广泛的关注.通过从作用机理与实验研究方法等方面综述近些年来杜仲在降血压、抗氧化、抗疲劳、增强免疫作用、抗骨质疏松、抗肿瘤、保肝护肝、降血糖和抗衰老等生物活性的研究进展,旨在为深入了解杜仲的活性功效,进一步开展相关研究提供参考.     

microRNAs在肝细胞癌中的调控机制及临床应用

microRNA（miRNA）在人类恶性肿瘤的发生发展过程中起着重要作用。近期研究表明,miRNA通过结合特定靶标参与调控肝细胞癌（hepatocellularcarcinoma,HCC）的发生,可作为辅助生物标志物用于指导肝细胞癌的诊断和治疗,并为有效地监控和预防肝病提供了新途径。寻找miRNA靶标,阐明miRNA参与肝癌发生的调控机理,有利于肝癌的临床靶向基因治疗。通过总结miRNA在肝细胞癌中的调控机制及临床应用的研究进展,为寻找肝细胞癌早期诊断的生物标志物及介入治疗的靶点提供了参考。     

Chiral discrimination and interaction mechanism between enantiomers and serum albumins

The chiral discrimination studies of biological system are theoretically and practically significant for the development of chiral drugs and life science. Our work has embarked upon the interaction between serum albumin (SA) (including human SA and bovine SA), R,S‐1‐(4‐methoxyphenyl)ethylamine, and R,S‐1‐(3‐methoxyphenyl)ethylamine. The formation of intermediate transition state, binding sites, and chiral discrimination ability can be investigated by ultraviolet‐visible spectra and fluorescence spectra. Moreover, both the changes of hydrophobic microenvironment and energy transfer can be detected by synchronous fluorescence spectra and fluorescence lifetime. Copyright © 2013 John Wiley & Sons, Ltd.     

Release,Regeneration and Mutant Induction of Pleurotus cornucopiae (‘Tamogitake’) Protoplasts

Both enantiomers of aliphatic and aromatic cyanohydrins were hydrolyzed with the aid of Rhodococcus butanica ATCC 21197 to afford optically active α-hydroxy acids. The usefulness of this reaction is demonstrated by the synthesis of optically pure (R)-4-dodecanolide, a defensive secretion of rove beetles, starting from (R)-2-hydroxydecanenitrile.     

Comparison of Soybean Tissue Extracted with Different Solvents

The enantioselective hydrolysis of (R,S)-3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H-[1,4]benzoxazine (I) with enzymes was investigated. Optically active I and its hydrolyzate, 7,8-difluoro-2,3-dihydro-3-hydroxymethyl-4H-[1,4]benzoxazine (II), are the intermediates for preparing optically active ofloxacins, whose racemate is known to be an excellent antibacterial agent. Lipoprotein lipase from Pseudomonas fluorescens (LPL Amano 3) was found to predominantly hydrolyze (S)-I, giving (R)-I in 54% e.e. and (R)-II in 44% e.e. On the other hand, lipase from Candida cylindracea was found to predominantly hydrolyze (R)-I, giving (S)-I in 24% e.e. and (S)-II in 20% e.e. Since, the optical purities of I and II thus obtained were not particularly high, these optically active I and II were converted into 3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4-(3,5-dinitrobenzoyl)-4H-[1,4]benzoxazine (IV). After recrystallizing IV from ethyl acetate-hexane, (S)- and (R)-II were obtained with high enantiomeric excess by removing the crystallized racemic IV and subsequently hydrolyzing the resulting optically active IV with alkali. The reduction of II afforded 7,8-difluoro-2,3-dihydro-3-methyl-4H-[1,4]benzoxazine (III), for which the optical purity was estimated to be >96%e.e. by HPLC analysis. (R)- and (S)-ofloxacin were prepared from (R)- and (S)-III with retention of their configuration.     

Synthesis of N-{2-O-2-Acetamido-1-O-acyl (or 1,6-di-O-acyl)-2,3-dideoxy-α-d-glucopyranose-3-yl]-d-lactoyl}-l-alanyl-d-isoglutamine Methyl Esters,and Their Immunoadjuvant Activities

A variety of 1-O-acyl and 1,6-di-O-acyl derivatives of N-acetylmuramoyl-l-alanyl-G-isoglutamine methyl esters were synthesized from N-[2-O-(2-acetamido-2,3-dideoxy-4,6-O-iso- propylidene-d-glucopyranose-3-yl)-d-lactoyl]-l-alanyl-d-isoglutamine methyl ester, and their biological activities were examined in guinea-pigs and mice.     

Production of Ethanol from Maltose by Zymobacter palmae Fermentation

The production of ethanol from maltose by Zymobacter palmae T109 in monoculture fermentations, and in co-culture fermentations together with Zymomonas mobilis B69 was studies. Zymobacter palmae T109, produced 5.5% (w/v) of ethanol when co-cultured with Zymomonas mobilis B69, but Zymobacter palmae T109 produced only 4.9% (w/v) ethanol from 15% (w/v) maltose medium in monoculture fermentation.