Four new steroidal glycosides from Solanum torvum and their cytotoxic activities

Two novel C-22 steroidal lactone saponins, namely solanolactosides A, B (1, 2) and two new spirostanol glycosides, namely torvosides M, N (3, 4) were isolated from ethanol extract of aerial parts of Solanum torvum. Their structures were characterized as solanolide 6-O-[α-l-rhamnopyranosyl-(1 → 3)-O-β-d-quinovopyranoside] (1), solanolide 6-O-[β-d-xylopyranosyl-(1 → 3)-O-β-d-quinovopyranoside] (2), yamogenin 3-O-[β-d-glucopyranosyl-(1 → 6)-O-β-d-glucopyranoside] (3) and neochlorogenin 3-O-[β-d-glucopyranosyl-(1 → 6)-O-β-d-glucopyranoside] (4) on the basis of spectroscopic analysis. The cytotoxicities of the saponins (1-4) were evaluated in vitro against a panel of human cancer cell lines. Compounds 3 and 4 showed significant cytotoxic activity with the cell lines.     

Absolutely conserved tryptophan in M49 family of peptidases contributes to catalysis and binding of competitive inhibitors

The role of the unique fully conserved tryptophan in metallopeptidase family M49 (dipeptidyl peptidase III family) was investigated by site-directed mutagenesis on human dipeptidyl peptidase III (DPP III) where Trp300 was subjected to two substitutions (W300F and W300L). The mutant enzymes showed thermal stability equal to the wild-type DPP III. Conservative substitution of the Trp300 with phenylalanine decreased enzyme activity 2-4 fold, but did not significantly change the K_m values for two dipeptidyl 2-naphthylamide substrates. However, the K_m for the W300L mutant was elevated 5-fold and the k_cat value was reduced 16-fold with Arg-Arg-2-naphthylamide. Both substitutions had a negative effect on the binding of two competitive inhibitors designed to interact with S1 and S2 subsites.These results indicate the importance of the aromatic nature of W300 in DPP III ligand binding and catalysis, and contribution of this residue in maintaining the functional integrity of this enzyme’s S2 subsite.     

Māori Culture on Stage: Authenticity and Identity in Tourist Interactions1

Cultural tourism is often described as inciting visited populations to adapt elements of their culture to the visitors' tastes instead of displaying their real way of life or identity. Even when researchers adopt a constructivist approach to authenticity, they often assume that it is defined according to the criteria or expectations of the tourists. In this paper, I analyse three Māori cultural shows in New Zealand, and explore the way cultural authenticity is defined in tourist interactions. I review the arguments in favour of rejecting the opposition between ‘inauthentic’ staged culture and ‘authentic’ daily life. My study tends to indicate that if authenticity is better described as a social construction, the host society might be more active in this process than visitors.     

A semimechanistic model predicting the growth and production of the bioenergy crop Miscanthus×giganteus: description, parameterization and validation

Biomass based bioenergy is promoted as a major sustainable energy source which can simultaneously decrease net greenhouse gas emissions. Miscanthus × giganteus ( M. × giganteus ), a C₄ perennial grass with high nitrogen, water, and light use efficiencies, is regarded as a promising energy crop for biomass production. Mathematical models which can accurately predict M. × giganteus biomass production potential under different conditions are critical to evaluate the feasibility of its production in different environments. Although previous models based on light-conversion efficiency have been shown to provide good predictions of yield, they cannot easily be used in assessing the value of physiological trait improvement or ecosystem processes. Here, we described in detail the physical and physiological processes of a previously published generic mechanistic eco-physiological model, WIMOVAC, adapted and parameterized for M. × giganteus . Parameterized for one location in England, the model was able to realistically predict daily field diurnal photosynthesis and seasonal biomass at a range of other sites from European studies. The model provides a framework that will allow incorporation of further mechanistic information as it is developed for this new crop.     

Occurrence of Macrosiphum hellebori Theobald & Walton (Hemiptera: Aphididae) in Australia

The European aphid species, Macrosiphum hellebori , the hellebore aphid, is recorded from Australia, having been found in Melbourne, Victoria and in Canberra, Australian Capital Territory, colonising ornamental hellebores, Helleborus species (Ranunculaceae). Insect associates of M. hellebori are recorded, including the hymenopterous primary parasite Lysiphlebus testaceipes (Cresson) (Braconidae: Aphidiinae). Keys are provided for the identification of the three species of Macrosiphum Passerini known from Australia.     

Detection and characterization of gamete-specific molecules in Mytilus edulis using selective antibody production

The mussel Mytilus edulis can be used as model to study the molecular basis of reproductive isolation because this species maintains its species integrity, despite of hybridizing in zones of contact with the closely related species M. trossulus or M. galloprovincialis. This study uses selective antibody production by means of hybridoma technology to identify molecules which are involved in sperm function of M. edulis. Fragmented sperm were injected into mice and 25 hybridoma cell clones were established to obtain monoclonal antibodies (mAb). Five clones were identified producing mAb targeting molecules putatively involved in sperm function based on enzyme immunoassays, dot and Western blotting as well as immunostaining of tissue sections. Specific localization of these mAb targets on sperm and partly also in somatic tissue suggests that all five antibodies bind to different molecules. The targets of the mAb obtained from clone G26-AG8 were identified using mass spectrometry (nano-LC-ESI-MS/MS) as M6 and M7 lysin. These acrosomal proteins have egg vitelline lyses function and are highly similar (76%) which explains the cross reactivity of mAb G26-AG8. Furthermore, M7 lysin was recently shown to be under strong positive selection suggesting a role in interspecific reproductive isolation. This study shows that M6 and M7 lysin are not only found in the sperm acrosome but also in male somatic tissue of the mantle and the posterior adductor muscle, while being completely absent in females. The monoclonal antibody G26-AG8 described here will allow elucidating M7/M6 lysin function in somatic and gonad tissue of adult and developing animals.     

Pilot-scale fermentation, purification, and characterization of recombinant human Oncostatin M in Pichia pastoris

Oncostatin M (OSM) is a multifunctional cellular regulator that belongs to the IL-6 subfamily and can act on a wide variety of cells, which has potential roles in the regulation of gene activation, cell survival, proliferation and differentiation. In order to achieve the higher level yield of recombinant human Oncostatin M (rhOSM), we determined the optimal pH condition of rhOSM expressed in the methylotrophic yeast Pichia pastoris X-33 and carried out the fermentation culture of rhOSM in 80 L fermentor in a fed-batch mode. SDS–PAGE and Western blotting assays demonstrated that rhOSM was successfully expressed and secreted into the culture medium with an apparent molecular weight of 28 kDa. N-terminals were correctly processed through amino-terminal sequencing. The maximum yield of rhOSM was 280 mg/L. rhOSM was purified by phenyl Sepharose hydrophobic interaction chromatography and SP Sepharose Fast Flow cation exchange chromatography, which resulted in a final yield of purified rhOSM of 6.94 g with a recovery of 62% and a purity of 95%. The purified rhOSM had a specific growth inhibition activity of 6.26 × 10⁴ RU/μg, which was commensurate with typical values (6.2 × 10⁴ RU/μg) obtained with standard hOSM.     

光学蛋白芯片技术在噬菌体M13KO7检测中的应用

将亲和素共价固定在表面改性后的硅片上,通过亲和素与生物素相互作用将生物素标记的噬菌体抗体GP3固定在亲和素膜层表面,当含有M13KO7噬菌体的样品经过抗体表面时,通过噬菌体与抗体之间的相互作用噬菌体就会被抗体捕获,生物学信号可以通过芯片上的膜层厚度变化表现出来,这种膜层厚度变化可以被椭偏生物传感器技术识别。结果表明,GP3抗体在芯片表面形成了饱和的抗体膜层,厚度为6.9nm;M13KO7噬菌体与芯片上固定的抗体会发生特异性相互作用,噬菌体被抗体捕获后形成的复合物膜层厚度为17.5nm,并且随着噬菌体浓度升高膜层厚度增加,检测含有M13KO7噬菌体的样品灵敏度为109pfu/mL。与其它研究病毒与抗体相互作用方法相比光学蛋白芯片技术具有简便快捷、无需标记待检样品和结果直观等优点,为研究病毒与其抗体相互作用以及疾病早期临床诊断提供了一个新的方法。     

GacA对假单胞菌株M18两个phz基因簇和菌群传感的调控

摘要:【目的】假单胞菌株M18（Pseudomonas sp. M18）是从甜瓜根际土壤中分离获得的一株对多种植物病原菌具有显著拮抗作用的菌株,在菌群传感（quorum sensing）系统的调控下,能分泌吩嗪-1-羧酸（PCA）以及多种吩嗪（phz）类衍生物的抗真菌物质。全局性因子GacA是M18菌株吩嗪类物质的合成与菌群传感系统的重要调控因子,本文将就GacA对上述两者的调控做进一步研究。【方法】PCR基因扩增和测序研究M18菌株中PCA合成基因簇,运用RT-PCR及构建phzA-lacZ转录融合手段