Triptolide suppresses pancreatic cancer cell proliferation by inhibiting hedgehog signaling pathway activity

正Dear Editor,Pancreatic cancer (PCa) is a high-grade gastrointestinal malignancy more commonly occurring in elderly populations with lower than 5% overall 5-year survival rate (Hidalgo, 2010). PCa responds poorly to most chemotherapeutic agents, and therefore it is imperative to develop novel therapeutic agents that have anti-cancer activities against PCa.     

Identification of a novel cognate cytosolic Hsp70 gene (MnHsc70-2) from oriental river prawn Macrobrachium nipponense and comparison of its expressions with the first cognate Hsc70 (MnHsc70-1) under different stresses

The 70-kDa family of heat-shock proteins (Hsp70) plays an important role in the host immunity, which is widely expressed in eukaryotic cells as a major chaperone protein. In the present study, the full-length complementary DNA (cDNA) of a second cognate cytosolic Hsp70 family member (MnHsc70-2) was cloned and characterized from Macrobrachium nipponense, which is an economically and nutritionally important crustacean. The cDNA was 2,717 bp, containing an open reading frame (ORF) of 1,950 bp, which encodes a protein of 649 amino acids with a theoretical molecular weight of 71.1 kDa and an isoelectric point of 5.27. Sequence alignment showed that the MnHsc70-2 shared 75–97 % identity with other heat-shock proteins. Compared to the previously identified cognate Hsp70 (MnHsc70-1) in M. nipponense, MnHsc70-2 showed quite different expression profiles under unstressed conditions in all tested tissues, including the hemocytes, heart, hepatopancreas, gill, intestine, nerve, and muscle. The phylogenetic analysis demonstrated that MnHsc70-2 showed the closest relationship with MnHsc70-1. Heat-inducibility assays showed that two isolated messenger RNAs (mRNAs) displayed different expression profiles in both the hepatopancreas and gill tissues. MnHsc70-1 mRNA expression level decreased at first and then increased to the normal level, whereas MnHsc70-2 mRNA level increased at first and then decreased. The expressions of two MnHsc70s showed substantial obvious heat-inducible regulation in both the hepatopancreas and gill. Under bacterial challenge by Aeromonas hydrophila, both MnHsc70-1 and MnHsc70-2 mRNA level was up-regulated moderately. The results suggested that two cognate Hsc70s may play essential functions in mediating responses to heat-shock and bacterial challenge.     

Punctal plugs versus artificial tears for treating dry eye: a comparative observation of their effects on contrast sensitivity

This study aimed to compare the effects of treatment with punctal plugs versus artificial tears on visual function and tear film stability for dry eye. A total of 56 consecutive eyes of 28 dry eye patients observed at our clinic from May to October in 2009 were divided into two groups. One group (32 eyes of 16 patients) was treated with artificial tears, and punctal plugs were used in the other group (24 eyes of 12 patients). A questionnaire was used in these patients before treatment and was repeated 2 weeks after treatment. Fluorescent staining for tear film break-up time (BUT), the Schirmer test I (STI), and contrast sensitivity was performed at the same time. The questionnaire indicated that all patients complained about the uncomfortable symptoms associated with dry eye. These symptoms were relieved after the application of artificial tears or punctal plugs, and there was no significant difference between these two groups. We found that the corneal fluorescent staining disappeared after treatment. The BUT was improved significantly after treatment in both groups, but the improvement was greater in patients who received punctal plugs than those that received artificial tears. There was no remarkable change in the STI in the artificial tears group, but a significant change was observed in the punctal plugs group. The contrast sensitivities were greatly improved in simulated daylight, night, and glare disability conditions after treatment with artificial tears and punctal plugs. However, the changes in contrast sensitivity did not significantly differ between groups. Both artificial tears and punctal plugs relieved dry eye symptoms, repaired corneal lesions, enhanced tear film stability, and improved contrast sensitivity. Punctal plugs could improve tear film stability and elongate the BUT better than artificial tears.     

Effect of influent substrate ratio on anammox granular sludge: performance and kinetics

Effect of influent substrate ratio on anammox process was studied in sequencing batch reactor. Operating temperature was fixed at 35 ± 1 °C. Influent pH and hydraulic retention time were 7.5 and 6 h, respectively. When influent NO₂ ^?-N/NH₄ ⁺-N was no more than 2.0, total nitrogen removal rate (TNRR) increased whereas NH₄ ⁺-N removal rate stabilized at 0.32 kg/(m³ d). ΔNO₂ ^?-N/ΔNH₄ ⁺-N increased with enhancing NO₂ ^?-N/NH₄ ⁺-N. When NO₂ ^?-N/NH₄ ⁺-N was 4.5, ΔNO₂ ^?-N/ΔNH₄ ⁺-N was 1.98, which was much higher than theoretical value (1.32). The IC₅₀ of NO₂ ^?-N was 289 mg/L and anammox activity was inhibited at high NO₂ ^?-N/NH₄ ⁺-N ratio. With regard to influent NH₄ ⁺-N/NO₂ ^?-N, the maximum NH₄ ⁺-N removal rate was 0.36 kg/(m³ d), which occurred at the ratio of 4.0. Anammox activity was inhibited when influent NH₄ ⁺-N/NO₂ ^?-N was higher than 5.0. With influent NO₃ ^?-N/NH₄ ⁺-N of 2.5–6.5, NH₄ ⁺-N removal rate and NRR were stabilized at 0.33 and 0.40 kg/(m³ d), respectively. When the ratio was higher than 6.5, nitrogen removal would be worsened. The inhibitory threshold concentration of NO₂ ^?-N was lower than NH₄ ⁺-N and NO₃ ^?-N. Anammox bacteria were more sensitive to NO₂ ^?-N than NH₄ ⁺-N and NO₃ ^?-N. TNRR would be enhanced with increasing nitrogen loading rate, but sludge floatation occurred at high nitrogen loading shock. The Han-Levenspiel could be applied to simulate nitrogen removal resulting from NO₂ ^?-N inhibition.     

广州帽峰山主要常绿阔叶林植物区系成分分析

对帽峰山主要常绿阔叶林植物区系成分进行了分析。14400m^2的典型样地调查结果表明;群落共有维管束植物209种,隶属于77科147属,数量优势科为大戟科、樟科、茜草科、禾本科、紫金牛科、蝶形花科、山茶科和冬青科。从属的地理分布区类型来看,以泛热带分布属的比例最高,其次为旧世界热带分布属和热带亚洲分布属,群落缺乏典型的热带成分,但具有南亚热带植物区系的基本特征。     

微生物发酵法生产聚羟基脂肪酸酯的研究进展

聚残基脂肪酸醋(Polyhydroxyalkanoates,PHAs)是一类由择基脂肪酸单体通过酯化聚合得到的高分子化合物,因具有传统石油基塑料类似的力学特征、100％生物降解性和生物相容性而被认为是最有潜力的绿色环保材料之一.受限于其高昂的生产成本,PHAs作为绿色环保材料的应用推广困难.文中分别从细胞形态调控、代谢...     

Molecular and functional analysis of phosphomannomutase (PMM) from higher plants and genetic evidence for the involvement of PMM in ascorbic acid biosynthesis in Arabidopsis and Nicotiana benthamiana

Phosphomannomutase (PMM) catalyzes the interconversion of mannose-6-phosphate and mannose-1-phosphate. However, systematic molecular and functional investigations on PMM from higher plants have hitherto not been reported. In this work, PMM cDNAs were isolated from Arabidopsis, Nicotiana benthamiana, soybean, tomato, rice and wheat. Amino acid sequence comparisons indicated that plant PMM proteins exhibited significant identity to their fungal and mammalian orthologs. In line with the similarity in primary structure, plant PMM complemented the sec53-6 temperature sensitive mutant of Saccharomyces cerevisiae. Histidine-tagged Arabidopsis PMM (AtPMM) purified from Escherichia coli converted mannose-1-phosphate into mannose-6-phosphate and glucose-1-phosphate into glucose-6-phosphate, with the former reaction being more efficient than the latter one. In Arabidopsis and N. benthamiana, PMM was constitutively expressed in both vegetative and reproductive organs. Reducing the PMM expression level through virus-induced gene silencing caused a substantial decrease in ascorbic acid (AsA) content in N. benthamiana leaves. Conversely, raising the PMM expression level in N. benthamiana using viral-vector-mediated ectopic expression led to a 20-50% increase in AsA content. Consistent with this finding, transgenic expression of an AtPMM-GFP fusion protein in Arabidopsis also increased AsA content by 25-33%. Collectively, this study improves our understanding on the molecular and functional properties of plant PMM and provides genetic evidence on the involvement of PMM in the biosynthesis of AsA in Arabidopsis and N. benthamiana plants.