CADMIUM AND MANGANESE ACCUMULATION IN PHYTOLACCA AMERICANA L. AND THE ROLES OF NON-PROTEIN THIOLS AND ORGANIC ACIDS

Phytolacca americana L. can accumulate large amounts of heavy metals in its aerial tissues, especially cadmium (Cd) and manganese (Mn). It has great potential for use in phytoextraction of metals from multi-metal-contaminated soils. This study was conducted to further investigate the Cd- and Mn-tolerance strategies of this plant. Concentrations of non-protein thiols (NPTs) and phytochelatins (PCs) in leaves and roots increased significantly as the concentration of Cd in solution increased. The molar ratios of PCs:soluble Cd ranged from 1.8 to 3.6 in roots and 8.1 to 31.6 in leaves, suggesting that the cellular response involving PC synthesis was sufficient to complex Cd ions in the cytosol, especially that of leaves. In contrast, excess Mn treatments did not result in a significant increase in NPT or PC concentrations in leaves or roots. Oxalic acid concentrations in leaves of plants exposed to 2 or 20 mM Mn reached 69.4 to 89.3 mg (0.771 to 0.992 mmol) g^–1 dry weight, respectively, which was approximately 3.7- to 8.6-fold higher than the Mn level in the 0.6 M HCl extract. Thus, oxalic acid may play an important role in the detoxification of Mn.     

Prediction of Drug-Target Interactions for Drug Repositioning Only Based on Genomic Expression Similarity

Small drug molecules usually bind to multiple protein targets or even unintended off-targets. Such drug promiscuity has often led to unwanted or unexplained drug reactions, resulting in side effects or drug repositioning opportunities. So it is always an important issue in pharmacology to identify potential drug-target interactions (DTI). However, DTI discovery by experiment remains a challenging task, due to high expense of time and resources. Many computational methods are therefore developed to predict DTI with high throughput biological and clinical data. Here, we initiatively demonstrate that the on-target and off-target effects could be characterized by drug-induced in vitro genomic expression changes, e.g. the data in Connectivity Map (CMap). Thus, unknown ligands of a certain target can be found from the compounds showing high gene-expression similarity to the known ligands. Then to clarify the detailed practice of CMap based DTI prediction, we objectively evaluate how well each target is characterized by CMap. The results suggest that (1) some targets are better characterized than others, so the prediction models specific to these well characterized targets would be more accurate and reliable; (2) in some cases, a family of ligands for the same target tend to interact with common off-targets, which may help increase the efficiency of DTI discovery and explain the mechanisms of complicated drug actions. In the present study, CMap expression similarity is proposed as a novel indicator of drug-target interactions. The detailed strategies of improving data quality by decreasing the batch effect and building prediction models are also effectively established. We believe the success in CMap can be further translated into other public and commercial data of genomic expression, thus increasing research productivity towards valid drug repositioning and minimal side effects.     

MRE11 is required for homologous synapsis and DSB processing in rice meiosis

Mre11, a conserved protein found in organisms ranging from yeast to multicellular organisms, is required for normal meiotic recombination. Mre11 interacts with Rad50 and Nbs1/Xrs2 to form a complex (MRN/X) that participates in double-strand break (DSB) ends processing. In this study, we silenced the MRE11 gene in rice and detailed its function using molecular and cytological methods. The OsMRE11-deficient plants exhibited normal vegetative growth but could not set seed. Cytological analysis indicated that in the OsMRE11-deficient plants, homologous pairing was totally inhibited, and the chromosomes were completely entangled as a formation of multivalents at metaphase I, leading to the consequence of serious chromosome fragmentation during anaphase I. Immunofluorescence studies further demonstrated that OsMRE11 is required for homologous synapsis and DSB processing but is dispensable for meiotic DSB formation. We found that OsMRE11 protein was located on meiotic chromosomes from interphase to late pachytene. This protein showed normal localization in zep1, Oscom1 and Osmer3, as well as in OsSPO11-1 ^RNAi plants, but not in pair2 and pair3 mutants. Taken together, our results provide evidence that OsMRE11 performs a function essential for maintaining the normal HR process and inhibiting non-homologous recombination during meiosis.     

嫩江高峰林区鸟类迁徙与气象因子的相关性初探

2001～2010年在黑龙江省嫩江县高峰林场开展了鸟类环志研究工作,共环志鸟类173种238672只,其中春季142种102285只,秋季147种136387只,隶属14目41科。春季以小鹀Emberiza pusilla、红胁蓝尾鸲Tar-siger cyanurus、黄眉柳莺Phylloscopus inornatus、栗鹀E.rutila、黄眉鹀E.chrysophrys、燕雀Fringilla montifringilla、田鹀E.rustica、黄雀Carduelis spinus等8种为迁徙鸟类的优势种,累计75145只,占春季环志数量的73.5%;秋季以白腰朱顶雀Carduelis flammea、黄雀、田鹀、燕雀、黄眉柳莺、煤山雀Parus ater、北朱雀Carpodacus roseus等7种为迁徙鸟类的优势种,累计99335只,占秋季环志数量的72.8%。利用统计软件对气象因子中的平均气温、日最高气温、日最低气温、平均水汽压、日最低气压、日最高气压、相对湿度、地面平均温度、平均风速、最大风速、最大风速的风向、日照时数与春秋季迁徙鸟类的优势种的相关性进行了分析,发现地面平均温度、日最高气温与鸟类迁徙的相关性很强。在春季,与鸟类迁徙的相关性很强的还有日最高气压,而秋季则是日照时数。相对湿度在鸟类迁徙中呈很强的负相关。     

Responses of plant 15N natural abundance and isotopic fractionation to N addition reflect the N status of a temperate steppe in China

Aims Elevated anthropogenic nitrogen (N) deposition could alter N status in temperate steppe. However, threshold observations of N status change from N limit to N saturation by far are not conclusive in these ecosystems. Research on the natural abundance of¹⁵N (δ¹⁵N) could greatly help provide integrated information about ecosystem N status. The goal of this study was to investigate the suitability of measurements of δ¹⁵N of major ecosystem N pools and several key species, plant¹⁵N fractionation, together with key vegetation and soil indicators in response to N fertilization as a tool to identify the N status in a temperate steppe in Inner Mongolia.     

One-step isolation of adenosine triphosphate from crude fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel

Adenosine triphosphate (ATP) is an important high-energy compound widely used in biological and therapeutic fields. It can be produced by phosphorylation of adenosine monophosphate (AMP) with microbial cells in industrial scale and the effective isolation of ATP from microbial fermentation broth is a challenging work. In this work, we develop a novel one-step method to directly separate ATP from fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel. The cryogel bed with tertiary amine groups was prepared by grafting N,N-dimethylaminoethyl methacrylate (DMAEMA) monomer chains onto the matrix of a polyacrylamide-based cryogel in a glass column and its properties of liquid dispersion, water permeability, porosity as well as the ligand density were measured. Chromatographic separation of ATP from the fermentation broth by the cryogel was carried out using deionised water and 0.01 M HCl as running buffer, respectively. The breakthrough characteristics and elution performance in the cryogel bed were revealed and analyzed. The purities of the obtained ATP were analyzed quantitatively by high performance liquid chromatography (HPLC). The maximal purity of ATP by the one-step separation method was 95.5% using 0.01 M HCl as running buffer in this work. The corresponding chromatographic behaviors were investigated and analyzed.     

Hi-Meth：特定位点DNA甲基化高通量检测平台

胞嘧啶甲基化是DNA表观遗传修饰的主要类型之一,在维持正常细胞功能和调控基因表达中具有重要作用。重亚硫酸盐测序法(bisulfite sequencing PCR,BSP)是特异性位点DNA甲基化检测的通用方法,能明确目的片段中每一个CpG位点的甲基化状态,但此方法需要大量的单克隆测序,操作过程较繁琐、成本昂贵。因此,开发准确、高效、便捷的DNA甲基化检测技术对提升表观遗传研究效率具有重要意义。基于本课题组开发的高通量突变类型检测平台Hi-TOM (high-throughput tracking of mutations),我们进一步建立了特定位点DNA甲基化高通量检测平台Hi-Meth (high-throughput detection of DNA methylation)。DNA样品通过重亚硫酸盐处理之后,仅需一轮PCR扩增即可通过Hi-Meth平台获得特定位点DNA甲基化分析结果。利用Hi-Meth平台,对水稻不同基因启动子区域进行了DNA甲基化检测分析,并与基于BSP方法获得的结果进行了比较。结果表明,Hi-Meth策略与BSP策略检测结果基本一致。而且通过Hi-Meth平台可以更准确、便捷地获得特异性位点DNA甲基化分析结果。综上所述,Hi-Meth为特定DNA区域提供了重要的甲基化检测平台,对表观遗传研究具有重要意义。     

Effects of High-Potassium-Induced Depolarization on Amino Acid Chemistry of the Dorsal Cochlear Nucleus in Rat Brain Slices

High K⁺ was used to depolarize glia and neurons in order to study the effects on amino acid release from and concentrations within the dorsal cochlear nucleus (DCN) of brain slices. The release of glutamate, -aminobutyrate (GABA) and glycine increased significantly during exposure to 50 mM K⁺, while glutamine and serine release decreased significantly during and/or after exposure, respectively. After 10 min of exposure to 50 mM K⁺, glutamine concentrations increased in all three layers of DCN slices, to more than 5 times the values in unexposed slices. In the presence of a glutamate uptake blocker, L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC), glutamine concentrations in all layers did not increase as much during 50 mM K⁺. Similar but smaller changes occurred for serine. Mean ATP concentrations were lower in 50 mM K⁺-exposed slices compared to control. The results suggest that depolarization, such as during increased neural activity, can greatly affect amino acid metabolism in the cochlear nucleus.