西双版纳勐养自然保护区砂仁类型的初步研究

通过西双版纳自然保护区勐养保护区栽培砂仁和野生缩砂密的实地调查 ,比较了二者的形态特征 ,以及考证了植物分类学上缩砂密是砂仁变种的确立过程后认为 :缩砂密是我国云南南部地区、广西、广东及毗邻国家山地广泛分布的野生类型 ,其个体之间的差异明显 ,表现出多态性 .砂仁集中栽培于广东西南部 ,尽管个体之间也有差异 ,但其变异范围包含在缩砂密的变异范围内 ,是从缩砂密中选育出来的栽培类型 .二者之间的差异属于种群内的多型性 .缩砂密种群内丰富多样性为各地选育株系奠定了基础 .     

Hydrogen protects against hyperoxia-induced apoptosis in type II alveolar epithelial cells via activation of PI3K/Akt/Foxo3a signaling pathway

Oxidative stress is regarded as a key regulator in the pathogenesis of prolonged hyperoxia-induced lung injury, which causes injury to alveolar epithelial cells and eventually leads to development of bronchopulmonary dysplasia (BPD). Many studies have shown that hydrogen has a protective effect in a variety of cells. However, the mechanisms by which hydrogen rescues cells from damage due to oxidative stress in BPD remains to be fully elucidated. This study sought to evaluate the effects of hydrogen on hyperoxia-induced lung injury and to investigate the underlying mechanism. Primary type II alveolar epithelial cells (AECIIs) were divided into four groups: control (21% oxygen), hyperoxia (95% oxygen), hyperoxia + hydrogen, and hyperoxia + hydrogen + LY294002 (a PI3K/Akt inhibitor). Proliferation and apoptosis of AECIIs were assessed using MTS assay and flow cytometry (FCM), respectively. Gene and protein expression were detected by quantitative polymerase chain reaction (q-PCR) and western blot analysis. Stimulation with hyperoxia decreased the expression of P-Akt, P- FoxO3a, cyclinD1 and Bcl-2. Hyperoxic conditions increased levels of Bim, Bax, and Foxo3a, which induced proliferation restriction and apoptosis of AECIIs. These effects of hyperoxia were reversed with hydrogen pretreatment. Furthermore, the protective effects of hydrogen were abrogated by PI3K/Akt inhibitor LY294002. The results indicate that hydrogen protects AECIIs from hyperoxia-induced apoptosis by inhibiting apoptosis factors and promoting the expression of anti-apoptosis factors. These effects were associated with activation of the PI3K/Akt/FoxO3a pathway.     

Different fermentation strategies by Schizochytrium mangrovei strain pq6 to produce feedstock for exploitation of squalene and omega‐3 fatty acids

Schizochytrium mangrovei strain PQ 6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA ) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L^?1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g^?1 · L^?1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g^?1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium .     

Escherichia coli biofilm: development and therapeutic strategies

Escherichia coli biofilm consists of a bacterial colony embedded in a matrix of extracellular polymeric substances (EPS) which protects the microbes from adverse environmental conditions and results in infection. Besides being the major causative agent for recurrent urinary tract infections, E. coli biofilm is also responsible for indwelling medical device‐related infectivity. The cell‐to‐cell communication within the biofilm occurs due to quorum sensors that can modulate the key biochemical players enabling the bacteria to proliferate and intensify the resultant infections. The diversity in structural components of biofilm gets compounded due to the development of antibiotic resistance, hampering its eradication. Conventionally used antimicrobial agents have a restricted range of cellular targets and limited efficacy on biofilms. This emphasizes the need to explore the alternate therapeuticals like anti‐adhesion compounds, phytochemicals, nanomaterials for effective drug delivery to restrict the growth of biofilm. The current review focuses on various aspects of E. coli biofilm development and the possible therapeutic approaches for prevention and treatment of biofilm‐related infections.     

Enhancing service capability with multiple finite capacity server queues in cloud data centers

Cloud computing took a step forward in the efficient use of hardware through virtualization technology. And as a result, cloud brings evident benefits for both users and providers. While users can acquire computational resources on-demand elastically, cloud vendors can also utilize maximally the investment costs for data centers infrastructure. In the Internet era, the number of appliances and services migrated to cloud environment increases exponentially. This leads to the expansion of data centers, which become bigger and bigger. Not just that these data centers must have the architecture with a high elasticity in order to serve the huge upsurge of tasks and balance the energy consumption. Although in recent times, many research works have dealt with finite capacity for single job queue in data centers, the multiple finite-capacity queues architecture receives less attention. In reality, the multiple queues architecture is widely used in large data centers. In this paper, we propose a novel three-state model for cloud servers. The model is deployed in both single and multiple finite capacity queues. We also bring forward several strategies to control multiple queues at the same time. This approach allows to reduce service waiting time for jobs and managing elastically the service capability for the whole system. We use CloudSim to simulate the cloud environment and to carry out the experiments in order to demonstrate the operability and effectiveness of the proposed method and strategies. The power consumption is also evaluated to provide insights into the system performance in respect of performance-energy trade-off.     

The conformation of acetylated virginiamycin M1 and virginiamycin M1 in explicit solvents

The three-dimensional structure of acetylated virginiamycin M(1) (acetylated VM1) in chloroform and in a water/acetonitrile mixture (83:17 v/v) have been established through 2D high resolution NMR experiments and molecular dynamics modeling and the results compared with the conformation of the antibiotic VM1 in the same and other solvents. The results indicated that acetylation of the C-14 OH group of VM1 caused it to rotate about 90 degrees from the position it assumed in non-acetylated VM1. The conformation of both VM1 and acetylated VM1 appear to flatten in moving from a nonpolar to polar solvent. However, the acetylated form has a more hydrophobic nature. The acetylated VM1 in chloroform and in water/acetonitrile solution had a similar configuration to that of VM1 bound to 50S ribosomes and to the Vat(D) active sites as previously determined by X-ray crystallography. Docking studies of VM1 to the 50S ribosomal binding site and the Vat(D) gave conformations very similar to those derived from X-ray crystallographic studies. The docking studies with acetylated VM1 suggested the possibility of a hydrogen bond from the acetyl carbonyl group oxygen of acetylated VM1 to the 2' hydroxyl group of ribose of adenosine 2538 at the ribosomal VM1 binding site. No hydrogen bonds between acetylated VM1 and the Vat(D) active sites were found; the loss of this binding interaction partly accounts for the release of the product from the active site.     

Stem cell properties and the side population cells as a target for interferon-alpha in adult T-cell leukemia/lymphoma

The cancer stem cell theory suggests that chemoresistance and recurrence of tumors are often due to the similarity of stem cell properties between normal and cancer cells. Adult T-cell leukemia/lymphoma (ATLL) has poor prognosis, suggesting that ATLL cells possess common stem cell properties. We analyzed side population (SP), a characteristic stem cell phenotype, and CD markers in ATLL cell lines. We found that several lines contained SP with expressions of some hematopoietic stem cell markers. On the other hand, treatment with interferon (IFN)-α is sometimes effective in ATLL, particularly combined with other drugs. We examined its effect on ATLL cells and found that IFN-α significantly reduced the SP proportion. Moreover, CD25-positive cells and phosphorylation of STAT1/5 and ERK were upregulated during this process. These data suggest that their stem cell properties render ATLL cells therapy-resistant, and IFN-α exerts its clinical effect through a reduction of the SP cell population.