Rice yellow stunt virus activates polyamine biosynthesis to promote viral propagation in insect vectors by disrupting ornithine decarboxylase antienzyme function

Intracellular polyamines(putrescine, spermidine, and spermine) have emerged as important molecules for viral infection;however, how viruses activate polyamines biosynthesis to promote viral infection remains unclear. Ornithine decarboxylase 1(ODC1) and its antienzyme 1(OAZ1) are major regulators of polyamine biosynthesis in animal cells. Here, we report that rice yellow stunt virus(RYSV), a plant rhabdovirus, could activate putrescine biosynthesis in leafhoppers to promote viral propagation by inhibiting OAZ1 expression. We observed that the reduction of putrescine biosynthesis by treatment with difluormethylornithine(DFMO), a specific nontoxic inhibitor of ODC1, or with in vitro synthesized dsRNAs targeting ODC1 mRNA could inhibit viral infection. In contrast, the supplement of putrescine or the increase of putrescine biosynthesis by treatment with ds RNAs targeting OAZ1 mRNA could facilitate viral infection. We further determined that both RYSV matrix protein M and ODC1 directly bind to the ODC-binding domain at the C-terminus of OAZ1. Thus, viral propagation in leafhoppers would decrease the ability of OAZ1 to target and mediate the degradation of ODC1, which finally activates putrescine production to benefit viral propagation. This work reveals that polyamine-metabolizing enzymes are directly exploited by a vector-borne virus to increase polyamine production, thereby facilitating viral infection in insect vectors.     

Airway epithelial cells-Functional links between CFTR and anoctamin dependent Cl(-) secretion

Airways consist of a heterogeneous population of cells, comprising ciliated cells, Clara cells and goblet cells. Electrolyte secretion by the airways is necessary to produce the airway surface liquid that allows for mucociliary clearance of the lungs. Secretion is driven by opening of Cl(-) selective ion channels in the apical membrane of airway epithelial cells, through either receptor mediated increase in intracellular cAMP or cytosolic Ca(2+). Traditionally cAMP-dependent and Ca(2+)-dependent secretory pathways are regarded as independent. However, this concept has been challenged recently. With identification of the Ca(2+) activated Cl(-) channel TMEM16A (anoctamin 1) and with detailed knowledge of the cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR), it has become possible to look more closely into this relationship.     

模拟增温对中亚热带杉木人工林土壤磷有效性的影响

气候变暖改变与土壤磷循环相关的生物地球化学过程,对陆地生态系统磷循环产生直接或间接影响。为研究亚热带地区杉木人工林土壤磷有效性对增温的响应,开展了模拟增温实验。实验设置对照组及增温组(5℃),经过1.5a的短期增温,对杉木人工林的土壤全磷、有机磷、微生物量磷、有效磷、酸性磷酸酶活性及相关土壤理化性质进行测定,结果表明:增温处理下,土壤酸性磷酸酶活性提高约1.5倍,土壤全磷、微生物量磷以及有机磷含量分别减少了6%、34%和12%,土壤有效磷含量增加25%。可见,短期增温通过提高土壤磷酸酶活性进而促进土壤有机磷矿化和降低土壤微生物固磷量,从而增加土壤磷有效性,但是增温导致潜在可利用的土壤微生物量磷大幅度的降低,将有可能加剧亚热带杉木人工林土壤磷限制。     

Effect of Chronic Administration of Low Dose Rapamycin on Development and Immunity in Young Rats

Mammalian target of rapamycin (mTOR) regulates cell growth, cell differentiation and protein synthesis. Rapamycin, an inhibitor of mTOR, has been widely used as an immunosuppressant and anti-cancer drug. Recently, mTOR inhibitors have also been reported to be a potential anti-epileptic drug, which may be effective when used in young patients with genetic epilepsy. Thus, a suitable dose of rapamycin which can maintain the normal function of mTOR and has fewer side effects ideally should be identified. In the present study, we first detected changes in marker proteins of mTOR signaling pathway during development. Then we determined the dose of rapamycin by treating rats of 2 weeks of age with different doses of rapamycin for 3 days and detected its effect on mTOR pathway. Young rats were then treated with a suitable dose of rapamycin for 4 weeks and the effect of rapamycin on mTOR, development and immunity were investigated. We found that the expression of the marker proteins of mTOR pathway was changed during development in brain hippocampus and neocortex. After 3 days of treanent, 0.03 mg/kg rapamycin had no effect on phospho-S6, whereas 0.1, 0.3, 1.0 and 3.0 mg/kg rapamycin inhibited phospho-S6 in a dose-dependent manner. However, only 1.0 mg/kg and 3.0 mg/kg rapamycin inhibited phospho-S6 after 4 weeks treatment of rapamycin. Parallel to this result, rats treated with 0.1 and 0.3 mg/kg rapamycin had no obvious adverse effects, whereas rats treated with 1.0 and 3.0 mg/kg rapamycin showed significant decreases in body, spleen and thymus weight. Additionally, rats treated with 1.0 and 3.0 mg/kg rapamycin exhibited cognitive impairment and anxiety as evident by maze and open field experiments. Furthermore, the content of IL-1β, IL-2, IFN-γ, TNF-α in serum and cerebral cortex were significantly decreased in 1.0 and 3.0 mg/kg rapamycin-treated rats. The expression of DCX was also significantly decreased in 1.0 and 3.0 mg/kg rapamycin-treated rats. However, rats treated with 1.0 mg/ kg rapamycin exhibited fewer and milder side effects than those treated with 3.0 mg/kg. In summary, all these data suggest that there is not a rapamycin dose that can inhibit mTOR for epilepsy without causing any side effects, but 1 mg /kg may be the optimal dose for young rats for suppressing mTOR with relatively few side effects.     

Molecular determinants for ATP-binding in proteins: a data mining and quantum chemical analysis

Adenosine 5'-triphosphate (ATP) plays an essential role in all forms of life. Molecular recognition of ATP in proteins is a subject of great importance for understanding enzymatic mechanism and for drug design. We have carried out a large-scale data mining of the Protein Data Bank (PDB) to analyze molecular determinants for recognition of the adenine moiety of ATP by proteins. Non-bonded intermolecular interactions (hydrogen bonding, pi-pi stacking interactions, and cation-pi interactions) between adenine base and surrounding residues in its binding pockets are systematically analyzed for 68 non-redundant, high-resolution crystal structures of adenylate-binding proteins. In addition to confirming the importance of the widely known hydrogen bonding, we found out that cation-pi interactions between adenine base and positively charged residues (Lys and Arg) and pi-pi stacking interactions between adenine base and surrounding aromatic residues (Phe, Tyr, Trp) are also crucial for adenine binding in proteins. On average, there exist 2.7 hydrogen bonding interactions, 1.0 pi-pi stacking interactions, and 0.8 cation-pi interactions in each adenylate-binding protein complex. Furthermore, a high-level quantum chemical analysis was performed to analyze contributions of each of the three forms of intermolecular interactions (i.e. hydrogen bonding, pi-pi stacking interactions, and cation-pi interactions) to the overall binding force of the adenine moiety of ATP in proteins. Intermolecular interaction energies for representative configurations of intermolecular complexes were analyzed using the supermolecular approach at the MP2/6-311 + G* level, which resulted in substantial interaction strengths for all the three forms of intermolecular interactions. This work represents a timely undertaking at a historical moment when a large number of X-ray crystallographic structures of proteins with bound ATP ligands have become available, and when high-level quantum chemical analysis of intermolecular interactions of large biomolecular systems becomes computationally feasible. The establishment of the molecular basis for recognition of the adenine moiety of ATP in proteins will directly impact molecular design of ATP-binding site targeted enzyme inhibitors such as kinase inhibitors.     

Genomics and expression analysis of DHHC-cysteine-rich domain S-acyl transferase protein family in apple

S-acylation is one of a group of lipid modifications that occurs on eukaryotic proteins, mediated by DHHC-CRD-containing proteins, which plays an important role in regulating the membrane association, trafficking and function of target proteins. Although genome-wide identification of PAT family has been carried out in yeast, mice, humans and Arabidopsis, little is known about apple PAT genes. In this study, a total of 33 putative apple PAT proteins, containing DHHC-CRD by domain analysis, have been identified, and were classified into three groups according to the phylogenetic analysis of PAT proteins in apple and Arabidopsis. More complex TMDs in the most MdPATs revealed the PM location of the gene family. Gene structure, gene chromosomal location and paralogs analysis of MdPAT genes within the apple genome demonstrated that tandem and segmental duplications, as well as whole genome duplications, have likely contributed to the expansion and evolution of the PAT gene family in apple. According to the microarray and expressed sequence tag (ESTs) analysis, the different expression patterns indicate that they may play different roles during fruit development and rootstock-scion interactions process. Moreover, PATs were performed expression profile analyses in different tissues, indicating that the PATs are involved in various aspects of physiological and developmental processes of apple. To our knowledge, this is the first report of a genome-wide analysis of the apple PAT gene family, and this genomic analysis of apple DHHC-CRD PAT genes provides the first step towards a functional study of this gene family in apple.     

戴云山黄山松林土壤碳组分的海拔变化特征及影响因素

海拔梯度可能通过多种环境因子影响土壤有机质,土壤有机碳库是土壤有机质的重要组成部分,其微小变化将会产生极其重要的影响。因此海拔差异可能导致海拔间土壤碳库差异。土壤有机碳是反映土壤肥力的重要指标,可能受土壤理化性质和微生物等多种因素的影响。黄山松是高山地绿化和用材的优良树种,近年来戴云山自然保护区内高海拔地区的黄山松群落呈现衰退趋势。研究戴云山黄山松林土壤有机碳组分沿海拔梯度的变化情况,不仅可以为该区域碳库估算提供科学依据,而且有助于揭示影响黄山松生长变化的机理。因此,选取戴云山不同海拔[1300 m (L)、1450 m (M)和1600 m (H)]梯度的黄山松林,对其土壤基本理化性质、有机碳组分及微生物特征进行测定和分析。研究发现,海拔梯度下土壤养分含量呈先升高后降低的变化趋势,土壤碳组分含量与其变化一致,且微生物生物量碳和微生物生物量氮均在M海拔处最高,海拔梯度对碳水解酶没有显著影响。冗余分析表明,总氮是影响土壤有机碳变化的最主要因素,其次是碳氮比。因此在海拔跨度不大的情况下,土壤有机碳动态可能主要受氮素而非温度的影响。高海拔地区土壤惰性碳占比高,未来可能会持续加剧该地区黄山松的...     

中亚热带森林转换对土壤磷积累的影响

磷是植物生长的必需元素之一,是维持亚热带森林生态系统生产力的关键因子。研究森林转换后土壤因素对磷素的影响,对生态系统的稳定和森林经营具有重要意义。选取由亚热带常绿阔叶林转换而成的米槠次生林(SF)、米槠人促林(AR)和杉木人工林(CF)为研究对象,测定了土壤理化性质、铁铝氧化物、各形态磷含量以及酸性磷酸酶活性,旨在探究土壤磷对森林转换的响应和驱动土壤磷变化的影响因子。结果显示:米槠人促林土壤的全磷、有机磷和微生物生物量磷显著高于米槠次生林和杉木人工林;冗余分析(RDA)发现,土壤含水量、总氮和无定型铁是影响淋溶层土壤磷的主要因子,而在淀积层,则是酸性磷酸酶、游离型铁和总氮起主要作用;土壤生物化学属性和微生物特性都会影响着不同形态土壤P的积累,其中土壤中的水分和酸性磷酸酶活性是调控土壤磷的关键因子。研究表明,中亚热带地区天然林转换为人促更新林更有利于森林土壤磷的储存和供应,有助于维持本区域森林生态系统的稳定。