The Arabidopsis Ethylene/Jasmonic Acid-NRT Signaling Module Coordinates Nitrate Reallocation and the Trade-Off between Growth and Environmental Adaptation

Stresses decouple nitrate assimilation and photosynthesis through stress-initiated nitrate allocation to roots (SINAR), which is mediated by the nitrate transporters NRT1.8 and NRT1.5 and functions to promote stress tolerance. However, how SINAR communicates with the environment remains unknown. Here, we present biochemical and genetic evidence demonstrating that in Arabidopsis thaliana, ethylene (ET) and jasmonic acid (JA) affect the crosstalk between SINAR and the environment. Electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that ethylene response factors (ERFs), including OCTADECANOID-RESPONSIVE ARABIDOPSIS AP2/ERF59, bind to the GCC boxes in the NRT1.8 promoter region, while ETHYLENE INSENSITIVE3 (EIN3) binds to the EIN3 binding site motifs in the NRT1.5 promoter. Genetic assays showed that cadmium and sodium stresses initiated ET/JA signaling, which converged at EIN3/EIN3-Like1 (EIL1) to modulate ERF expression and hence to upregulate NRT1.8. By contrast, ET and JA signaling mediated the downregulation of NRT1.5 via EIN3/EIL1 and other, unknown component(s). SINAR enhanced stress tolerance and decreased plant growth under nonstressed conditions through the ET/JA-NRT1.5/NRT1.8 signaling module. Interestingly, when nitrate reductase was impaired, SINAR failed to affect either stress tolerance or plant growth. These data suggest that SINAR responds to environmental conditions through the ET/JA-NRT signaling module, which further modulates stress tolerance and plant growth in a nitrate reductase-dependent manner.     

Activating Brown Adipose Tissue for Weight Loss and Lowering of Blood Glucose Levels: A MicroPET Study Using Obese and Diabetic Model Mice

Purpose

This study aims at using ¹⁸F-FDG microPET to monitor the brown adipose tissue (BAT) glucose metabolism in obese and diabetic mouse models under different interventions, and study the therapeutic potential of BAT activation for weight loss and lowering of blood glucose in these models.

Methods

Obese mice were established by a high-fat diet for eight weeks, and diabetes mellitus(DM) models were induced with Streptozocin in obese mice. ¹⁸F-FDG microPET was used to monitor BAT function during obese and DM modeling, and also after BRL37344 (a β₃-adrenergic receptor agonist) or levothyroxine treatment. The BAT function was correlated with the body weight and blood glucose levels.

Results

Compared with the controls, the obese mice and DM mice showed successively lower ¹⁸F-FDG uptake in the interscapular BAT (P = 0.036 and <0.001, respectively). After two-week BRL37344 treatment, the BAT uptake was significantly elevated in both obese mice (P = 0.010) and DM mice (P = 0.004), accompanied with significantly decreased blood glucose levels (P = 0.023 and 0.036, respectively). The BAT uptake was negatively correlated with the blood glucose levels in both obese mice (r = −0.71, P = 0.003) and DM mice (r = −0.74, P = 0.010). BRL37344 treatment also caused significant weight loss in the obese mice (P = 0.001). Levothyroxine treatment increased the BAT uptake in the control mice (P = 0.025) and obese mice (P = 0.013), but not in the DM mice (P = 0.45).

Conclusion

The inhibited BAT function in obese and DM mice can be re-activated by β₃-adrenergic receptor agonist or thyroid hormone, and effective BAT activation may lead to weight loss and blood glucose lowering. Activating BAT can provide a new treatment strategy for obesity and DM.     

SARS-CoV Sars7a和EGFP融合蛋白真核表达载体构建及其表达

根据SARS-CoV sars7a基因设计并化学合成部分重叠引物,经二轮PCR获得sars7a基因片段,以此片段为模板并利用一对带有Kozak序列及删除终止密码的引物进行PCR,获得产物与pEGFP-N1载体连接,使sars7a基因位于EGFP的基因上游,得到含编码Sars7a-EGFP融合蛋白基因的哺乳动物细胞表达载体.采用细胞核转染技术将重组表达载体转染K562细胞,以流式细胞仪和共聚焦显微镜分析,可检测到EGFP的绿色荧光,表明Sars7a-EGFP得到表达,该蛋白分布于整个细胞,提示Sars7a并非膜蛋白,更可能是胞浆蛋白.此外,该蛋白的表达对K562细胞凋亡无明显影响.     

檵木与红花檵木的解剖结构研究

对7个不同地点的野生檵木、野生红花檵木、栽培红花檵木花的解剖结构进行了研究,浏阳大围山野生檵木花的数性遗传结构与其它地区的野生檵木有较大差异,4数性花和5～6数性花各占50%;红花檵木野生和栽培类型均以5数性花数量居多,不同于文献记载的檵木属植物4数性花的分类属征(每朵花花瓣、雄蕊、退化雄蕊及萼片均为4数).利用花的结构遗传变异探讨了红花檵木的起源和品种演化历史.     

Gelation conditions and transport properties of hollow calcium alginate capsules

The diameter, membrane thickness, and compression intensity of hollow Ca-alginate capsules were measured at different gelation conditions, such as the reactant concentration, dropping velocity, and gelation time. The optimum operation conditions for preparing capsules were determined at 100 g/L CaCl(2), 10 g/L sodium alginate (Na-alginate), a dropping velocity of 150 droplets/min, and a gelation time of 10 min. Diffusion of some saccharide and amino acid from bulk solution into capsules was investigated, and the diffusion coefficients were calculated by the developed mathematical model. All the tested substances can diffuse easily into the capsules. The combined diffusion coefficients of the capsule D(m) are 92-99% as large as their diffusion coefficients in pure water, while the diffusion coefficients in the capsule membrane D(1) are 60-95% as large as those. By employing polyethylene glycol (PEG) and bovine serum albumin (fraction V) (BSA(V)), the molecular weight cut-off of the capsule was determined. For linear macromolecules, hollow Ca-alginate capsules have a molecular weight cut-off of 4000. No diffusion of BSA(V) into the capsules was observed.     

Current concepts on Escherichia coli K1 translocation of the blood-brain barrier

The mortality and morbidity associated with neonatal gram-negative meningitis have remained significant despite advances in antimicrobial chemotherapy. Escherichia coli K1 is the most common gram-negative organism causing neonatal meningitis. Our incomplete knowledge of the pathogenesis of this disease is one of the main reasons for this high mortality and morbidity. We have previously established both in vitro and in vivo models of the blood-brain barrier (BBB) using human brain microvascular endothelial cells (HBMEC) and hematogenous meningitis in neonatal rats, respectively. With these in vitro and in vivo models, we have shown that successful crossing of the BBB by circulating E. coli requires a high-degree of bacteremia, E. coli binding to and invasion of HBMEC, and E. coli traversal of the BBB as live bacteria. Our previous studies using TnphoA, signature-tagged mutagenesis and differential fluorescence induction identified several E. coli K1 determinants such as OmpA, Ibe proteins, AslA, TraJ and CNF1 contributing to invasion of HBMEC in vitro and traversal of the blood-brain barrier in vivo. We have shown that some of these determinants interact with specific receptors on HBMEC, suggesting E. coli translocation of the BBB is the result of specific pathogen-host cell interactions. Recent studies using functional genomics techniques have identified additional E. coli K1 factors that contribute to the high degree of bacteremia and HBMEC binding/invasion/transcytosis. In this review, we summarize the current knowledge on the mechanisms underlying the successful E. coli translocation of the BBB.     

Comparison of hybridization behavior between double and single strands of targets and the application of asymmetric PCR targets in cDNA microarray

Double stranded targets on the cDNA microarray contain representatives of both the coding and noncoding strands, which will introduce hybridization competition with probes. Here, the effect of double and single strands of targets on the signal intensity and the ratios of Cy5/Cy3 within the same slide were compared. The results show that single stranded targets can increase the hybridization efficiency without changing the Cy5/Cy3 ratio. Based on these results, a new strategy was established by generating cDNA targets with asymmetric PCR, instead of conventional PCR, to increase the sensitivity of the cDNA microarray. Furthermore, the feasibility of this approach was validated. The results indicate that the cDNA microarray system based on asymmetric PCR is more sensitive, with no decrease in the reliability and reproducibility as compared with that based on conventional symmetric PCR.     

香港嘉道理农场次生林区碰撞诱捕网和黑光灯捕虫器采集所得鞘翅目甲虫多样性比较

本文根据1990-1995年在香港嘉道理农场次生林区采集的昆虫标本,首次分析了鞘翅目及其优势科的种类、数量和季节性变化,以及由碰撞诱捕网和黑光灯捕虫器采集所得甲虫在种类、数量和季节性上的差异。在13260号标本中,已鉴定到科的有13253号,分属45科,231种。其中,朽木甲科(Alleculidae)、毛蕈甲科(Biphyllidae)、丸甲科(Byrrhidae)、坚甲科(Colydiidae)、拟球甲科(Corylophidae)、隐食甲科(Cryptophagidae)、水缨甲科(Hydroscaphidae)、伪叶甲科(Lagliidae)、薪甲科(Lathridiidae)、泽甲科(Limnichidae)、黑蕈甲科(Zopheridae)等11个科为香港地区的首次报道,约占本次调查科总数的25％。分析表明：(1)该次生林区的鞘翅目甲虫以蛀木性为主。天牛科(Cerambycidae)、瓢虫科(Coccinellidae)、象甲科(Curculionidae)、花蚤科(Mordellidae)、金龟甲科(Scarabaeidae)、小蠹科(Scolytidae)等6科均为多样性较高(种类≥15或者个体数量≥200)的优势科。(2)鞘翅目个体数量季节性明显,每年自2月开始数量逐渐增加,6—7月为甲虫发生的高峰期,8月显著减少。各优势科甲虫的季节性也存在一定的差异,庞大的小蠹标本数量(85％)说明在此调查期间该科正处于大发生时期。(3)黑光灯捕虫器所捕的甲虫科类和种类较之碰撞诱捕网所捕不尽相同,黑光灯捕虫器所捕的甲虫数量发生高峰期比碰撞诱捕网所捕的甲虫提前一个月。(4)各项多样性指数对不同捕虫器采集所得鞘翅目的测度差异明显,黑光灯捕虫器所捕甲虫的多样度和均匀度指数高于碰撞诱捕网。     

分子佐剂C3d3增强hCGβ蛋白疫苗免疫原性及其抗血清中和hCG生物学活性的作用

本文观察分子佐剂C3d3增强hCGβ蛋白避孕疫苗体液免疫效力的能力。采用分子生物学技术以phCMV1为载体分别构建分泌型、带有6个组氨酸纯化标签的真核表达质粒phCMV1-6His-hCGβ-C3d3和phCMV1-6His-hCGβ,在CHO细胞中获得重组蛋白的稳定、高效表达,并用镍柱和凝胶过滤层析对其进行分离、纯化。分别用hCGβ-C3d3融合蛋白、hCGβ 弗氏佐剂和单用hCGβ免疫生育期雌性BALB／c小鼠,共免疫两次,间隔4周。ELISA测定血清中抗hCGβ抗体滴度,并对各组小鼠产生的抗血清中和hCG生物学活性的能力进行比较。结果表明hCGβ单独免疫组在加强免疫后才见抗体生成,其抗体滴度比hCGβ-C3d3融合蛋白免疫组低1995倍,C3d3的佐剂能力是弗氏佐剂的10倍(初次免疫)-32倍(再次免疫),并且hCGβ-C3d3融合蛋白免疫小鼠产生的抗血清具有很强的中和hCG生物学活性的作用。实验证明通过分子佐剂C3d3可以大幅提高机体对hCGβ的体液免疫应答能力。     

A highly bioactive lignophenol derivative from bamboo lignin exhibits a potent activity to suppress apoptosis induced by oxidative stress in human neuroblastoma SH-SY5Y cells

Approaches to protection against neurodegenerative diseases, in which oxidative stress and inflammation are implicated, should be based on the current concept on the etiology of these diseases. Recently, a new therapeutic strategy has been proposed to protect neurons from cell death by attenuating the apoptotic signal transduction. Lignin, a durable aromatic network polymer second to cellulose in abundance, was able to be converted into highly active lignophenol derivatives with antioxidant activity by using our newly developed phase-separation technique. These lignophenol derivatives were found to show the potent neuroprotective activity against oxidative stress. Among the compounds examined, a lignocresol derivative from bamboo (lig-8) exhibited the most potent neuroprotective activity against hydrogen peroxide (H(2)O(2))-induced apoptosis in human neuroblastoma cell line SH-SY5Y by preventing the caspase-3 activation via either caspase-8 or caspase-9. Furthermore, it was found that lig-8 exerted the antiapoptotic effect by inhibiting dissipation of the mitochondrial membrane permeability transition induced by H(2)O(2) or by the peripheral benzodiazepin receptor ligand PK11195. Lig-8 was also shown to be potent in the antioxidant activity in the cells exposed to H(2)O(2), as assessed by flow cytometry using 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate and in vitro reactive oxygen species-scavenging potency. These data suggest that lig-8 is a promising neuroprotector, which affects the signaling pathway of neuronal cell death and that it would be of benefit to delay the progress of neurodegenerative diseases.