Escherichia coli SufE Sulfur Transfer Protein Modulates the SufS Cysteine Desulfurase through Allosteric Conformational Dynamics

Fe-S clusters are critical metallocofactors required for cell function. Fe-S cluster biogenesis is carried out by assembly machinery consisting of multiple proteins. Fe-S cluster biogenesis proteins work together to mobilize sulfide and iron, form the nascent cluster, traffic the cluster to target metalloproteins, and regulate the assembly machinery in response to cellular Fe-S cluster demand. A complex series of protein-protein interactions is required for the assembly machinery to function properly. Despite considerable progress in obtaining static three-dimensional structures of the assembly proteins, little is known about transient protein-protein interactions during cluster assembly or the role of protein dynamics in the cluster assembly process. The Escherichia coli cysteine desulfurase SufS (EC 2.8.1.7) and its accessory protein SufE work together to mobilize persulfide from l-cysteine, which is then donated to the SufB Fe-S cluster scaffold. Here we use amide hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize SufS-SufE interactions and protein dynamics in solution. HDX-MS analysis shows that SufE binds near the SufS active site to accept persulfide from Cys-364. Furthermore, SufE binding initiates allosteric changes in other parts of the SufS structure that likely affect SufS catalysis and alter SufS monomer-monomer interactions. SufE enhances the initial l-cysteine substrate binding to SufS and formation of the external aldimine with pyridoxal phosphate required for early steps in SufS catalysis. Together, these results provide a new picture of the SufS-SufE sulfur transferase pathway and suggest a more active role for SufE in promoting the SufS cysteine desulfurase reaction for Fe-S cluster assembly.     

Effect of maysin on wild-type,deltamethrin-resistant,and Bt-resistant Helicoverpa armigera (Lepidoptera: Noctuidae)

Larvae of the Old World corn earworm, Helicoverpa armigera (Hübner), were fed diets containing lyophilized silks from maize genotypes expressing varying levels of maysin, a flavone glycoside known to be toxic to the New World corn earworm, Helicoverpa zea Boddie. Three different H. armigera colonies were tested: a wild-type colony (96-S), a colony selected for resistance to deltamethrin (Del-R), and a colony selected for resistance to the Cry1Ac protoxin of Bacillus thuringiensis (Bt-R). A colony of H. zea was also tested as a control. High-maysin silk diets significantly slowed the growth and arrested the development of larvae from all H. armigera colonies compared with low-maysin silk diets, maysin-lacking silk diets, and no-silk control diets. The effects on the H. armigera and H. zea colonies were similar across maysin levels, although H. zea is a larger insect than H. armigera and this overall size difference was observed. Among the H. armigera colonies, maysin effects were generally similar, although 7-d-old Del-R larvae were significantly smaller than 7-d-old Bt-R and 96-S larvae for one no-silk control and two maysin-containing silk treatments. The toxic effect of maysin on the Bt-R and Del-R colonies suggests that physiological mechanisms of H. armigera resistance to Cry1Ac and deltamethrin do not confer cross-resistance to maysin.     

Benzothiophenes containing a piperazine side chain as selective ligands for the estrogen receptor alpha and their bioactivities in vivo

The synthesis of benzothiophenes containing a piperazine side chain and their binding affinities for estrogen receptors are described. These compounds bearing piperazine side chains were identified to be high-affinity ligands with high selectivity for ER alpha subtype. They were also potent agonists in bone tissue.     

Colloidal Bismuth Pectin: An Alternative to Bismuth Subcitrate for the Treatment of Helicobacter pylori– Positive Duodenal Ulcer

Background. Bismuth triple therapy provides consistently good results in Helicobacter pylori eradication worldwide, whereas quadruple therapy using a combination of omeprazole and bismuth triple regimen has produced cure rates in excess of 90%. The prevalence of metronidazole-resistant strains was 26.8% in our area. Colloidal bismuth pectin (CBP) is a new, lower-priced bismuth salt made in China. The purpose of this study was to investigate the efficacy and safety of CBP triple and quadruple regimens in the treatment of H. pylori–positive duodenal ulcer. Materials and Methods. In this prospective trial, 205 patients with H. pylori–positive duodenal ulcer were allocated randomly to receive one of four regimens: metronidazole, 200 mg; amoxicillin, 250 mg; and colloidal bismuth subcitrate (CBS), 120 mg (group 1), or CBP, 100 mg qid (group 2) for 2 weeks, then continued CBS, 240 mg, or CBP, 200 mg bid for a further 2 weeks. A quadruple regimen using a combination of omeprazole, 20 mg bid, and CBS triple therapy (group 3) or CBP triple therapy (group 4), respectively, was given to patients for 1 week, followed by omeprazole, 20 mg once daily for a further 3 weeks. Further endoscopy was performed at least 4 weeks after cessation of the treatment. H. pylori status was determined by histology, a ¹⁴C urea breath test, and a urease test. Results. The per-protocol H. pylori cure rates were 85% (22 of 26 patients), 90% (35 of 39), 96% (46 of 48), and 95% (75 of 79) for groups 1 through 4. In the intention-to-treat analysis, cure rates were 79% (22 of 28), 83% (35 of 42), 90% (46 of 51), and 89% (75 of 84), respectively. The cure rates of quadruple therapy were higher than those of triple therapy; an 8.2% difference was not statistically significant (95% confidence interval [CI], 2.3–18.7%). The ulcer-healing rates were 88%, 87%, 98%, and 97%, respectively, for groups 1 through 4. The ulcer pain was relieved more rapidly in quadruple- than in triple-therapy regimens. Two patients discontinued treatment prematurely owing to drug-related side effects. Conclusion. One-week quadruple therapy is highly effective and safe in H. pylori eradication in Chinese patients. CBP is as effective as CBS.     

棉铃虫飞翔肌的超微结构

利用电子显微镜观测表明,棉铃虫Helicoverpa rmigera (Hubner)飞翔肌的肌原纤维由400～800根肌球蛋白丝组成,每根肌球蛋白由6根肌动蛋白丝环绕排列成六角形,肌节长度2.0～3.5μm,线粒体占飞翔肌的体积达42.38%～48.57%,微气管组织较为发达。初羽化棉铃虫肌原纤维和线粒体的发育基本完成,横管系统的发育相对较慢,羽化3日后趋于成熟,至5日龄占飞翔肌的体积达3.31%～3.54%。表明棉铃虫具有适宜飞行的飞翔肌结构。采自渤海海面距海岸线80km的迁飞蛾子飞翔肌基本结构和实验种群无明显的区别,但迁飞过程中的能量代谢导致线粒体内脊疏松而出现大量空洞。     

不同抗性水平棉铃虫地理种群的基因交流对抗性演化的影响

采自我国长江流域棉区的棉铃虫Helicoverpa armigera(Hubner)四川简阳种群、湖北武穴种群、湖南衡阳种群、江苏南京种群和浙江杭州种群对辛硫磷、三氟氯氰菊酯和硫丹的抗性水平分别为8.05～38.80、2.86～290.00和5.87～19.83倍。抗性较高的简阳种群和较低的杭州种群正、反交F₁代对上述3种农药的抗性为13.16和16.69倍、10.43和19.00倍及12.42和10.21倍,抗性遗传的显性系数为-0.2220、-0.2147和0.0700,表明对辛硫磷、三氟氯氰菊酯抗性呈不完全隐性方式遗传,而硫丹抗性则为半隐性遗传。P1自交F2代对辛硫磷、三氟氯氰菊酯和硫丹的抗性水平分别为17.66、7.57和9.03倍,F₁代对杭州种群回交F₂代的抗性倍数分别为8.79、3.Oo和6.61。其结果,高抗区和低抗区棉铃虫种群的基因流动将导致对三种农药抗性水平明显下降。     

棉铃虫对溴氰菊酯的抗性遗传及其生化机理

用经室内诱导的抗溴氰菊酯棉铃虫Helicoverpa armigera(Hubner)种群与室内饲养多年的敏感种群进行杂交,研究了棉铃虫对溴氰菊酯的抗性遗传规律。结果表明：杂交后的显性度(D)分别为0.34和0.35,F₁与亲本回交的期望值与实际值在比值是1 ∶1时差异显著,回交平台在35%～45%,棉铃虫对溴氰菊酯的抗性可能是一个以上主基因的不完全显性遗传。生化分析表明,抗性种群的。-乙酸萘酯酶活力与敏感种群的差异显著,这可能是棉铃虫对溴氰菊酯产生高抗药性的重要解毒酶之一。     

Effects of solvent on inclusion complexation of a chiral dipeptide toward racemic BINOL

The effects of reaction solvent on inclusion complexation of a chiral dipeptide (3S,6S)‐ 1 derived from (S)‐proline toward racemic BINOL was investigated, discovering that the reaction solvent played a crucial role in determining the inclusion complexation behavior of dipeptide (3S,6S)‐ 1 toward rac‐BINOL. (3S,6S)‐ 1 did not show any chiroselective or achiroselective complexation toward rac‐BINOL in polar protic solvents such as methanol and ethanol, polar aprotic solvents including trichloromethane and THF, while in polar aprotic solvent ethyl acetate and apolar aprotic solvents benzene, (3S,6S)‐ 1 displayed achiroselective complexation toward rac‐BINOL. However, the resulting heterocomplex HC‐ 2 from benzene and HC‐ 3 from ethyl acetate have a different composition. Single crystal X‐ray diffraction analysis demonstrates that the two heterocomplexes are formed via different H‐bond interaction patterns, in which the reaction solvent has a dramatic effect. Furthermore, this work provides a relatively green method for quantitative enantiomeric enrichment of nonracemic BINOL, in which unacceptable and toxic benzene was replaced by ethyl acetate.     

Inhibition of Autophagy by Chloroquine Enhances the Antitumor Efficacy of Sorafenib in Glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive and common brain tumor in adults. Sorafenib, a multi-kinase inhibitor, has been shown to inhibit cell proliferation and induce apoptosis through inhibition of STAT3 signaling in glioblastoma cells and in intracranial gliomas. However, sorafenib also induces cell autophagy. Due to the dual roles of autophagy in tumor cell survival and death, the therapeutic effect of sorafenib on glioblastoma is uncertain. Here, we combined sorafenib treatment in GBM cells (U373 and LN229) and tumors with the autophagy inhibitor chloroquine. We found that blockage of autophagy further inhibited cell proliferation and migration and induced cell apoptosis in vitro and in vivo. These findings suggest the possibility of combination treatment with sorafenib and autophagy inhibitors for GBM.     

核型高梁雄性不育自然突变体的研究

本文对多穗高梁自然突变体(多A)进行了细胞学、遗传学和同工酶电泳的分析研究,取得以下结果: “多A”雄性不育性状由一对细胞核隐性等位基因控制,它与核、质型雄性不育系(3A)之间未发现有亲缘关系。染色体行为在减数分裂过程中有数目不等的不联会、早离及落后现象发生,正常染色体数目为n=10。“多A”不育花粉单核期的过氧化物同工酶为11条带,“多B”可育花粉为8条带。三核期的花粉,“多A”为7条带,“多B”为5条带。