MicroRNA profiles in Sorghum exposed to individual drought or heat or their combination

Sorghum is largely grown for food, fodder and for biofuel production in semi-arid regions where the drought or high temperature or their combination co-occur. Plant microRNAs (miRNAs) are integral to the gene regulatory networks that control almost all biological processes including adaptation to stress conditions. Thus far, plant miRNA profiles under separate drought or heat stresses have been reported but not under combined drought and heat. In this study, we report miRNA profiles in leaves of sorghum exposed to individual drought or heat or their combination. Approximately 29 conserved miRNA families represented by 80 individual miRNAs, 26 families represented by 47 members of less conserved or sorghum-specific miRNA families as well as 8 novel miRNA families have been identified. Of these, 25 miRNAs were found to be differentially regulated in response to stress treatments. The comparative profiling revealed that the miRNA regulation was stronger under heat or combination of heat and drought compared to the drought alone. Furthermore, using degradome sequencing, 48 genes were confirmed as targets for the miRNAs in sorghum. Overall, this study provides a framework for understanding of the miRNA-guided gene regulations under combined stresses.

     

唐古特白刺果粉的抗氧化作用研究

通过自由基体系和亚硝酸盐体系对白刺果粉体外总抗氧化活性进行了评价,为进一步开发利用白刺资源提供理论依据和试验资料。结果表明,白刺果粉具有良好的抗氧化活性,能有效清除DPPH.、.OH、O2-.、亚硝酸盐,其清除效果与果粉浓度成正相关,最高清除率分别达到65.7%、71.5%、83.8%和71%。     

Mechanism of template-independent nucleotide incorporation catalyzed by a template-dependent DNA polymerase

Numerous template-dependent DNA polymerases are capable of catalyzing template-independent nucleotide additions onto blunt-end DNA. Such non-canonical activity has been hypothesized to increase the genomic hypermutability of retroviruses including human immunodeficiency viruses. Here, we employed pre-steady state kinetics and X-ray crystallography to establish a mechanism for blunt-end additions catalyzed by Sulfolobus solfataricus Dpo4. Our kinetic studies indicated that the first blunt-end dATP incorporation was 80-fold more efficient than the second, and among natural deoxynucleotides, dATP was the preferred substrate due to its stronger intrahelical base-stacking ability. Such base-stacking contributions are supported by the 41-fold higher ground-state binding affinity of a nucleotide analog, pyrene nucleoside 5'-triphosphate, which lacks hydrogen bonding ability but possesses four conjugated aromatic rings. A 2.05 A resolution structure of Dpo4*(blunt-end DNA)*ddATP revealed that the base and sugar of the incoming ddATP, respectively, stack against the 5'-base of the opposite strand and the 3'-base of the elongating strand. This unprecedented base-stacking pattern can be applied to subsequent blunt-end additions only if all incorporated dAMPs are extrahelical, leading to predominantly single non-templated dATP incorporation.     

Overexpression of the soybean GmWNK1 altered the sensitivity to salt and osmotic stress in Arabidopsis

The WNK (With No Lysine K) serine-threonine kinases have been shown to be osmosensitive regulators and are critical for cell volume homeostasis in humans. We previously identified a soybean root-specific WNK homolog, GmWNK1, which is important for normal late root development by fine-tuning regulation of ABA levels. However, the functions of WNKs in plant osmotic stress response remains uncertain. In this study, we generated transgenic Arabidopsis plants with constitutive expression of GmWNK1. We found that these transgenic plants had increased endogenous ABA levels and altered expression of ABA-responsive genes, and exhibited a significantly enhanced tolerance to NaCl and osmotic stresses during seed germination and seedling development. These findings suggest that, in addition to regulating root development, GmWNK1 also regulates ABA-responsive gene expression and/or interacts with other stress related signals, thereby modulating osmotic stress responses. Thus, these results suggest that WNKs are members of an evolutionarily conserved kinase family that modulates cellular response to osmotic stresses in both animal and plants.     

伤胁迫对蚕豆叶片中茉莉酸分布的影响

在植物应对伤害等环境刺激的反应中,已知茉莉酸(JA)作为一种重要的信号分子在植物体内长距离运输,但目前对JA的细胞和亚细胞定位知之甚少。本研究用免疫荧光显微镜技术和免疫胶体金电镜技术证明茉莉酸分布在蚕豆叶片叶肉细胞的叶绿体、表皮细胞的细胞壁、保卫细胞的细胞壁、细胞质、叶绿体和细胞核上。其中保卫细胞的叶绿体和细胞核是JA分布的主要场所。叶片的局部灼伤可提高JA在质外体和气孔保卫细胞中的水平。由此推测,伤胁迫下JA分配的改变可能与植物体防御反应密切相关,并参与了对气孔运动的调控。     

微小根毛霉感染机理研究

本文在首次报告二例肺结核、糖尿病患者合并感染肺微小根毛霉的基础上,进一步探讨免疫功能受损与微小根毛霉感染关系。本文采用不同剂量~(60)Co-γ全身辐照小鼠,然后以不同途径注射同剂量的微小根毛霉的孢囊孢子,观察动物的感染情况和感染后的真菌检出率,结果发现各种辐射剂量均在辐射后7-14日感染菌的检出率最高;各种脏器感染菌的检出率以脾脏最高(66.7—81.8％);淋巴结最低(0.0—25.0％);其他脏器的感染菌检出率也有不同程度的差异。     

三种不同方法固定的石蜡切片中RNA的分析

研究在 10 %中性福尔马林、丙酮、甲醇 氯仿 冰醋酸 3种方法固定的石蜡切片中提取RNA的质量和数量 .取 2 5 0g体重的Wistar大鼠的肾脏 ,分别采用 10 %中性福尔马林、丙酮、甲醇 氯仿 冰醋酸 3种方法固定 ,石蜡包埋 ,H E染色 ;采用RNA裂解液、TRIZOL试剂 2种方法提取切片RNA ,逆转录为cDNA ,采用普通PCR和SYBRGREEN 1定量PCR分析RNA质量和数量 .结果表明 ,3种固定方法都可保持组织良好的结构和形态 ;采用 2种提取方法 ,均可经RT PCR扩增出 180bp大鼠磷酸甘油醛脱氢酶 (G3PDH)、5 6 5bpβ肌动蛋白 (β actin)、10 0bp纤溶酶系活化剂抑制物 1(PAI 1) ;但采用RNA裂解液时 ,比TRIZOL试剂可提取更多的RNA .     

Reduction/pH dual-sensitive PEGylated hyaluronan nanoparticles for targeted doxorubicin delivery

To minimize the side effect of chemotherapy, a novel reduction/pH dual-sensitive drug nanocarrier, based on PEGylated dithiodipropionate dihydrazide (TPH)-modified hyaluronic acid (PEG-SS-HA copolymer), was developed for targeted delivery of doxorubicin (DOX) to hepatocellular carcinoma. The copolymer was synthesized by reductive amination via Schiff's base formation between TPH-modified HA and galactosamine-conjugated poly(ethylene glycol) aldehyde/methoxy poly(ethylene glycol) aldehyde. Conjugation of DOX to PEG-SS-HA copolymer was accomplished through the hydrazone linkage formed between DOX and PEG-SS-HA, and confirmed by FTIR and ¹H NMR spectra. The polymer–DOX conjugate could self-assemble into spherical nanoparticles (∼150 nm), as indicated by TEM and DLS. In vitro release studies showed that the DOX-loaded nanoparticles could release DOX rapidly under the intracellular levels of pH and glutathiose. Cellular uptake experiments demonstrated that the nanoparticles could be efficiently internalized by HepG2 cells. These results indicate that the PEG-SS-HA copolymer holds great potential for targeted intracellular delivery of DOX.     

Transfected Eimeria tenella could complete its endogenous development in vitro

Live attenuated coccidiosis vaccines could be used as powerful carriers, expressing exogenous viral and bacterial antigens, to induce protective immunity against pathogenic organisms. We investigated the ability of Eimeria tenella to express an exogenous gene in vitro. Eimeria tenella sporozoites were transfected with the plasmid pH4-2EYFP-Actin3 containing the yellow fluorescent protein gene (yfp) and inoculated into primary chicken kidney cells (PCKCs), followed by incubation at 41 C in a 5% CO2 chamber. Fluorescent sporozoites were observed as early as 15-20 hr post-inoculation (PI). Fluorescence displayed by the expressed YFP protein was visible throughout the schizogony and gametogony stages of the tranfected E. tenella. Fluorescent oocysts were found between 200-327 hr PI. Higher fluorescence intensity was observed in the nucleus than in other compartments of the transfectants, while little or no fluorescence was seen in the refractile globule. The diversity of schizonts, particularly of the first generation, was presented by fluorescent nuclei arranged in different patterns. Our results demonstrated the ability of E. tenella to express an exogenous gene throughout the endogenous development in vitro. Completion of the endogenous development of transfected E. tenella in cell cultures will facilitate the study of foreign antigen expression in Eimeria spp., paving the way for the development of an Eimeria spp. vector vaccine that also carries and delivers other vaccines by oral administration.