Establishment, Growth kinetics, and Susceptibility to AcMNPV of Heat Tolerant Lepidop teran Cell Lines

Lepidopteran heat-tolerant(ht)cell lines have been obtained with sf-9,sf-21 and several Bombyx cells.They have a distinct karyotype,membrane lipid composition,morphology and growth kinetics from the parental cell lines.In this paper,we report the development of ht cell lines from other insect species and examination of their growth characteristics and virus susceptibility.Adaptation of cell lines sf-9,BTI-TN-5131-4(High5)and BTI-TN-MG1(MG 1)to 33℃ and 35℃ was carried out by shifting the culture temperature between 28℃ and higher temperatures by a gradual stepwise increase in temperature.The process of adaption to a higher culture temperature was accomplished over a period of 2 months.The cell lines with the temperature adaption were designated as sf9-ht33,sf9-ht35,High5-ht33,High5-ht35,MG1-ht33,MG1-ht35.These cell lines have been subcultured over 70 passages.Adaption to high temperatures was confirmed by a constant population doubling time with individual cell lines.The population doubling time of heat adapted cell lines were 1-4 h less than these of parental cell lines.Cell shapes did not show obvious change,however,the cell size of sf9-ht cells was enlarged and those of High5 and MG1 ht cells were reduced after heat adaption.When the cell lines were infected with Autographa californica nuclear polyhedrosis virus(AcMNPV)at 28℃,33℃,35℃ and 37℃,production of budded virus and occlusion bodies in each cell line was optimum at its own adapted temperature.     

Quantitative determination of trans-polydatin, a natural strong anti-oxidative compound, in rat plasma and cellular environment of a human colon adenocarcinoma cell line for pharmacokinetic studies

A simple, accurate, precise, specific and reproducible high-performance liquid chromatography (HPLC) method was developed for determination of trans-polydatin, a natural strong anti-oxidative compound, in rat plasma and cell suspension. The assay procedure involved simple liquid-liquid extraction, the supernatant liquid was added an equal volume of water to avoid solvent effect. The detection of the analyte peak was achieved by monitoring the eluate using a UV detector set at 303 nm. The analysis used a Hypersil ODS2 C18 column (5 microm, 4.6 mm x 250 mm) and methanol/distilled water as the mobile phase (flow rate=1 mL/min). A total analytical run was achieved within 6.0 min and calibration curve was linear over a wide concentration range of 0.25-40 microg/mL for plasma sample and 1.0-500 microM for cell suspension, the coefficients of correlation were 0.9997 and 0.9999 or better, respectively. There was 80.7+/-7.86%, 96.8+/-3.20% and 102.7+/-9.72% recovery from 0.5, 10, and 40 microg/mL plasma samples, respectively. Intra- and inter-batch accuracy and precision were acceptable for the both matrices. The RSD of intra- and inter-day assay variations were all less than 10%. Both analyte and IS were stable in the battery of stability studies, freeze-thaw cycles. The described assay method was applied to pharmacokinetic studies in rats and a human colon adenocarcinoma cell line (Caco-2) successfully. The application of the assay to determine the pharmacokinetic is described.     

Pituitary adenylate cyclase-activating polypeptide is up-regulated in cortical pyramidal cells after focal ischemia and protects neurons from mild hypoxic/ischemic damage

The protective effect of pituitary adenylate cyclase-activating polypeptide (PACAP) in stroke models is poorly understood. We studied patterns of PACAP, vasoactive intestinal peptide, and the PACAP-selective receptor PAC1 after middle cerebral artery occlusion and neuroprotection by PACAP in cortical cultures exposed to oxygen/glucose deprivation (OGD). Within hours, focal ischemia caused a massive, NMDA receptor (NMDAR)-dependent up-regulation of PACAP in cortical pyramidal cells. PACAP expression dropped below the control level after 2 days and was normalized after 4 days. Vasoactive intestinal peptide expression was regulated oppositely to that of PACAP. PAC1 mRNA showed ubiquitous expression in neurons and astrocytes with minor changes after ischemia. In cultured cortical neurons PACAP27 strongly activated Erk1/2 at low and p38 MAP kinase at higher nanomolar concentrations via PAC1. In astrocyte cultures, effects of PACAP27 on Erk1/2 and p38 were weak. During OGD, neurons showed severely reduced Erk1/2 activity and dephosphorylation of Erk1/2-regulated Ser112 of pro-apoptotic Bad. PACAP27 stimulation counteracted Erk1/2 inactivation and Bad dephosphorylation during short-term OGD but was ineffective after expanded OGD. Consistently, PACAP27 caused MEK-dependent neuroprotection during mild but not severe hypoxic/ischemic stress. While PACAP27 protected neurons at 1–5 nmol/L, full PAC1 activation by 100 nmol/L PACAP exaggerated hypoxic/ischemic damage. PACAP27 stimulation of astrocytes increased the production of Akt-activating factors and conferred ischemic tolerance to neurons. Thus, ischemia-induced PACAP may act via neuronal and astroglial PAC1. PACAP confers protection to ischemic neurons by maintaining Erk1/2 signaling via neuronal PAC1 and by increasing neuroprotective factor production via astroglial PAC1.     

Robustness of neural codes and its implication on natural image processing

In this study, based on the view of statistical inference, we investigate the robustness of neural codes, i.e., the sensitivity of neural responses to noise, and its implication on the construction of neural coding. We first identify the key factors that influence the sensitivity of neural responses, and find that the overlap between neural receptive fields plays a critical role. We then construct a robust coding scheme, which enforces the neural responses not only to encode external inputs well, but also to have small variability. Based on this scheme, we find that the optimal basis functions for encoding natural images resemble the receptive fields of simple cells in the striate cortex. We also apply this scheme to identify the important features in the representation of face images and Chinese characters.

Exploration of the binding mode of α/β-type small acid soluble proteins (SASPs) with DNA

The α/β-type small acid soluble proteins (SASPs) are a major factor in protecting the spores from being killed in bacteria. In this article, we perform a systematic phylogenetic analysis of the α/β-type SASP in the genus of Geobacillus, which indicates that the whole family can be divided into three groups. We choose one protein from each group as a representative and construct the tertiary structure of these proteins. In order to explore the mechanism of protecting DNA from damage, 15 ns molecular dynamics simulation for the four complexes of Gsy3 with DNA are performed. The sequence alignment, model structure and binding energy analysis indicate that the helix2 region of SASPs is more conserved and plays a more crucial role in protecting DNA. Pairwise decomposition of residue interaction energies calculation demonstrate that amino acids of Asn10, Lys24, Asn49, Ile52, Ile56, Thr57, Lys58, Arg59 and Val61 take major effect in the binding interaction. The differences of energy contribution of the amino acids between different complexes make us conclude that the protein structure conformation has a slight change upon more proteins binding to DNA and consequently there occur protein-protein cooperation interactions.     

Characteristic microbial community of a dry thermophilic methanogenic digester: its long-term stability and change with feeding

Thermophilic dry anaerobic digestion of sludge for cellulose methanization was acclimated at 53 °C for nearly 5 years using a waste paper-based medium. The stability of the microbial community structure and the microbial community responsible for the cellulose methanization were studied by 16S rRNA gene-based clone library analysis. The microbial community structure remained stable during the long-term acclimation period. Hydrogenotrophic methanogens dominated in methanogens and Methanothermobacter, Methanobacterium, Methanoculleus, and Methanosarcina were responsible for the methane production. Bacteria showed relatively high diversity and distributed mainly in the phyla Firmicutes, Bacteroidetes, and Synergistetes. Ninety percent of operational taxonomic units (OTUs) were affiliated with the phylum Firmicutes, indicating the crucial roles of this phylum in the digestion. Relatives of Clostridium stercorarium, Clostridium thermocellum, and Halocella cellulosilytica were dominant cellulose degraders. The acclimated stable sludge was used to treat garbage stillage discharged from a fuel ethanol production process, and the shift of microbial communities with the change of feed was analyzed. Both archaeal and bacterial communities had obviously changed: Methanoculleus spp. and Methanothermobacter spp. and the protein- and fatty acid-degrading bacteria became dominant. Accumulation of ammonia as well as volatile fatty acids led to the inhibition of microbial activity and finally resulted in the deterioration of methane fermentation of the garbage stillage.     

鹊肾树树皮的化学成分和抗炎作用研究

通过药理实验确定了鹊肾树树皮的乙酸乙酯萃取物为抗炎活性部位,并利用色谱技术从该部位中分离得到了7个化合物,通过UV、IR、NMR、MS等现代谱学方法鉴定化合物的结构分别为:丁二酸(1)、6-乙基-5-羟基-2,7-二甲氧基-1,4-萘醌(2)、3β,20-二羟基-5β-孕甾烷(3)、5-羟基麦芽酚(4)、双[5-甲酰基...     

TNF-α和IL-13对人肺成纤维细胞胶原蛋白生成的影响

以胶原蛋白过量沉积为主要特征的纤维化是临床肺部疾患常见的病理现象。该研究利用RT-PCR技术检测不同剂量TNF-α和IL-13对人肺成纤维细胞IL-13Rα1、IL-13Rα2和Ⅰ型胶原蛋白转录水平的影响;ELISA检测细胞培养上清sIL-13Rα2分泌量;羟脯氨酸法定量分析各组肺成纤维细胞胶原蛋白生成情况。结果发现:在实验剂量条件下,TNF-α和IL-13对人肺成纤维细胞IL-13Rα1的表达无显著影响;两者均能不同程度地上调IL-13Rα2的表达;与对照组相比,TNF-α对胶原蛋白的表达有下调作用,IL-13则无显著影响。