Renewable bio ionic liquids‐water mixtures‐mediated selective removal of lignin from rice straw: Visualization of changes in composition and cell wall structure

Pretreatment of rice straw by using renewable cholinium amino acids ionic liquids ([Ch][AA] ILs)‐water mixtures and the subsequent enzymatic hydrolysis of the residues were conducted in the present work. Of the eight mixtures composed of ILs and water, most were found to be effective for rice straw pretreatment. After pretreatment with 50% ILs‐water mixtures, the enzymatic digestion of the lignocellulosic biomass was enhanced significantly, thus leading to satisfactory sugar yields of >80% for glucose and approximately 50% for xylose. To better understand the ILs pretreatment mechanism, confocal laser scanning microscopy combined with immunolabeling and transmission electron microscopy were used to visualize changes in the contents and distribution of two major components—lignin and xylan. The results coupled with changes in chemical structures (infrared spectra) of the substrates indicated occurrence of extensive delignification, especially in cell corner and compound middle lumen of cell walls, which made polysaccharides more accessible to enzymes. This pretreatment process is promising for large‐scale application because of the high sugar yields, easy handling, being environmentally benign and highly tolerant to moisture, and significantly reduced cost and energy consumption. Biotechnol. Bioeng. 2013; 110: 1895–1902. © 2013 Wiley Periodicals, Inc.     

Altuibacter lentus gen. nov., sp. nov., a novel member of family Flavobacteriaceae isolated from deep seawater of the South China Sea

A novel chemoheterotrophic, aerobic, Gram-negative, rod-shaped, yellow-pigmented, bacterial strain JLT2010^T was isolated from deep seawater of the South China Sea. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain JLT2010^T belongs to the family Flavobacteriaceae and is most closely related to Ulvibacter antarcticus IMCC3101^T with 95.7 % similarity. Some phenotypic characteristics such as the absence of flexirubin-type pigments, growth at 37 °C, hydrolysis of casein differentiated strain JLT2010^T from the genus Ulvibacter as well as other genera in the family Flavobacteriaceae. The DNA G+C content of the strain JLT2010^T was found to be 35.7 mol% and the major respiratory quinone was found to be MK-6. On the basis of phenotypic and phylogenetic features, JLT2010^T is classified as a novel genus and species within the family Flavobacteriaceae, for which the name Altuibacter lentus gen. nov., sp. nov. is proposed. The type strain is JLT2010^T (=JCM 18884^T = CGMCC 1.12167^T).     

Understanding Dry Matter and Nitrogen Accumulation with Time-Course for High-Yielding Wheat Production in China

Understanding the time-course of dry matter (DM) and nitrogen (N) accumulation in terms of yield–trait relationships is essential to simultaneously increase grain yield and synchronize N demand and N supply. We collected 413 data points from 11 field experiments to address patterns of DM and N accumulation with time in relation to grain yield and management of winter wheat in China. Detailed growth analysis was conducted at the Zadok growth stages (GS) 25 (regreening), GS30 (stem elongation), GS60 (anthesis), and GS100 (maturity) in all experiments, including DM and N accumulation. Grain yield averaged 7.3 Mg ha⁻¹, ranging from 2.1 to 11.2 Mg ha⁻¹. The percent N accumulation was consistent prior to DM accumulation, while both DM and N accumulation increased continuously with growing time. Both the highest and fastest DM and N accumulations were observed from stem elongation to the anthesis stage. Significant correlations between grain yield and DM and N accumulation were found at each of the four growth stages, although no positive relationship was observed between grain yield and harvest index or N harvest index. The yield increase from 7–9 Mg ha⁻¹ to >9 Mg ha⁻¹ was mainly attributed to increased DM and N accumulation from stem elongation to anthesis. Although applying more N fertilizer increased N accumulation during this stage, DM accumulation was not improved, indicating that N fertilizer management and related agronomic management should be intensified synchronously across the wheat growing season to simultaneously achieve high yields and match N demand and N supply.     

Impairment of Endothelial-Myocardial Interaction Increases the Susceptibility of Cardiomyocytes to Ischemia/Reperfusion Injury

Endothelial-myocardial interactions may be critically important for ischemia/reperfusion injury. Tetrahydrobiopterin (BH₄) is a required cofactor for nitric oxide (NO) production by endothelial NO synthase (eNOS). Hyperglycemia (HG) leads to significant increases in oxidative stress, oxidizing BH₄ to enzymatically incompetent dihydrobiopterin. How alterations in endothelial BH₄ content impact myocardial ischemia/reperfusion injury remains elusive. The aim of this study was to examine the effect of endothelial-myocardial interaction on ischemia/reperfusion injury, with an emphasis on the role of endothelial BH₄ content. Langendorff-perfused mouse hearts were treated by triton X-100 to produce endothelial dysfunction and subsequently subjected to 30 min of ischemia followed by 2 h of reperfusion. The recovery of left ventricular systolic and diastolic function during reperfusion was impaired in triton X-100 treated hearts compared with vehicle-treated hearts. Cardiomyocytes (CMs) were co-cultured with endothelial cells (ECs) and subsequently subjected to 2 h of hypoxia followed by 2 h of reoxygenation. Addition of ECs to CMs at a ratio of 1∶3 significantly increased NO production and decreased lactate dehydrogenase activity compared with CMs alone. This EC-derived protection was abolished by HG. The addition of 100 µM sepiapterin (a BH₄ precursor) or overexpression of GTP cyclohydrolase 1 (the rate-limiting enzyme for BH₄ biosynthesis) in ECs by gene trasfer enhanced endothelial BH₄ levels, the ratio of eNOS dimer/monomer, eNOS phosphorylation, and NO production and decreased lactate dehydrogenase activity in the presence of HG. These results demonstrate that increased BH₄ content in ECs by either pharmacological or genetic approaches reduces myocardial damage during hypoxia/reoxygenation in the presence of HG. Maintaining sufficient endothelial BH₄ is crucial for cardioprotection against hypoxia/reoxygenation injury.     

铜绿假单胞菌cntRLMN操纵子介导锌离子摄取的功能鉴定

【目的】本研究以铜绿假单胞菌PAO1 (Pseudomonas aeruginosa PAO1,菌种编号ATCC15692)为对象,研究cntRLMN在锌离子摄取中的功能。【方法】在ΔznuBC的基础上,以同源重组的方法构建了cntRLMN的各种突变菌株,通过质粒接合转移的方法构建其互补菌株及lacZ转录融合报告菌株,运用β-半乳糖苷酶酶活检测研究了Zur蛋白对cntRLMN的转录调控,凝胶阻滞实验(EMSA)检验Zur蛋白与cnt启动子及cnt启动子的突变片段的体外结合,并进一步通过生长曲线分析对cntRLMN中cntR、cntL、cntN等基因的锌离子摄取功能进行了分析和鉴定。最终,通过构建大蜡螟幼虫的侵染模型来研究cntRLMN对铜绿假单胞菌毒力发挥的影响。【结果】lacZ转录融合的酶活分析显示cntRLMN受Zur蛋白的负调控,其表达以Zur蛋白依赖的方式受锌离子饥饿的诱导;EMSA实验的结果显示cntRLMN的启动子可以与His-Zur结合形成DNA-蛋白质复合体,结合位点为GCGTTATAGTATATCAT;生长曲线和大蜡螟幼虫侵染实验的分析结果显示ZnuBC和CntRLMN的功能存在互补性,仅znuBC和cntRLMN双缺失突变时菌株在限锌培养条件下的生长和对大蜡螟幼虫的毒性才受到显著抑制,说明CntRLMN代表另一种独立的锌离子摄取系统。【结论】cntRLMN是受Zur直接负调控的另一种独立的铜绿假单胞菌锌离子摄取系统,对铜绿假单胞菌毒力的发挥起重要作用。     

Glypican-5 is a tumor suppressor in non-small cell lung cancer cells

Glypican-5 (GPC5) belongs to the glypican family of proteoglycans that have been implicated in a variety of physiological processes, ranging from cell proliferation to morphogenesis. However, the role of GPC5 in human cancer remains poorly understood. We report that knockdown of GPC5 in bronchial epithelial cells promoted, and forced expression of GPC5 in non-small lung cancer (NSCLC) cells suppressed, the anchorage-independent cell growth. In vivo, expression of GPC5 inhibited xenograft tumor growth of NSCLC cells. Furthermore, we found that GPC5 was expressed predominantly as a membrane protein, and its expression led to diminished phosphorylation of several oncogenic receptor tyrosine kinases, including the ERBB family members ERBB2 and ERBB3, which play critical roles in lung tumorigenesis. Collectively, our results suggest that GPC5 may act as a tumor suppressor, and reagents that activate GPC5 may be useful for treating NSCLC.