Probing the dynamics of intact cells and nuclear envelope precursor membrane vesicles by deuterium solid state NMR spectroscopy

Membrane dynamics is an essential part of many cellular mechanisms such as intracellular trafficking, membrane fusion/fission and mitotic organelle reconstitution. The dynamics of membranes is dependent primarily on their phospholipid and cholesterol composition and how these molecules are ordered in relation to one another. To determine the physical status of membranes in whole cells or purified membranes of subcellular compartments we have developed a novel application exploiting solid-state ²H-NMR spectroscopy. We utilise this method to probe the dynamics of intact sperm and nuclear envelope precursor membranes. We show, using mass spectrometry, that either multilamellar or small unilamellar vesicles of deuterium-labelled palmitoyl-oleoylphosphatidylcholine can be used to probe the dynamics of sperm cells or nuclear envelope precursor membrane vesicles, respectively. Using ²H-NMR we determine the order parameters of sperm cells and nuclear envelope precursor membrane vesicles. We demonstrate that whole sperm membranes are more dynamic than nuclear envelope precursor membranes due to the higher cholesterol levels of the latter. Our new application can be exploited as a generic method for monitoring membrane dynamics in whole cells, various subcellular membrane compartments and membrane domains in subcellular compartments.     

Gene Therapy Strategies for Hepatocellular Carcinoma

Summary Hepatocellular carcinoma (HCC) is one of the most frequent cancers worldwide. Effective therapy to this cancer is currently lacking, creating an urgent need for new therapeutic strategies for HCC. Gene therapy approach that relies on the transduction of cells with genetic materials, such as apoptotic genes, suicide genes, genes coding for antiangiogenic factors or immunomodulatory molecules, small interfering RNA (siRNA), or oncolytic viral vectors, may provide a promising strategy. The aforementioned strategies have been largely evaluated in the animal models with HCC or liver metastasis. Due to the diversity of vectors and therapeutic genes, being used alone or in combination, gene therapy approach may generate great beneficial effects to control the growth of tumors within the liver.     

Adenovirus Serotype 5 Variants Defective in Early Genes: Selective Replication in p53-Deficient Human Tumor Cells

Site-directed mutagenesis was used to construct human adenovirus serotype 5 (Ad5) variants defective in E1A or E1B. Mutant Adel3 with deletion from E1A was markedly attenuated in permissive cell cultures regardless of the p53 status, and replicated efficiently only in cells of the complementing 293 line. Mutant Adel2 with deletion from E1B55K infected the 293 line cells and p53-deficient human tumor cells (A431, SW480, HEp2) with efficiencies similar to those of Ad5, whereas its replication in normal p53-positive cells was substantially limited. Thus, Adel2 proved to be capable of selective infection and lysis of p53-deficient human tumor cells in vitro. On intratumor injection, Adel2 dramatically suppressed the growth of human epidermoid carcinoma (A431) in nude mice. Adel2 is thus a promising model for designing therapeutic agents against p53-deficient human tumors.     

新城疫病毒抗肿瘤研究进展

新城疫病毒(Newcastle disease virus,NDV)为副黏病毒科,禽腮腺炎病毒属(Avulavirus)的禽副黏病毒Ⅰ型(APMV-Ⅰ),可对250多种禽类造成致死性感染,给世界范围内的家禽养殖造成了巨大损失。目前,研究发现NDV对人肿瘤细胞具有溶瘤作用,能够选择性地在癌细胞中复制。并且一些研究已经进行了人体临床试验,取得了良好的效果。因此,新城疫病毒是肿瘤治疗的潜在治疗剂。文中就NDV结构蛋白与毒力的关系、NDV直接溶瘤作用、NDV为载体的肿瘤基因治疗、NDV抗肿瘤与自噬等进行了综述。     

The causes of altered chlorophyll fluorescence quenching induction in the Arabidopsis mutant lacking all minor antenna complexes

Non-photochemical quenching (NPQ) of chlorophyll fluorescence is the process by which excess light energy is harmlessly dissipated within the photosynthetic membrane. The fastest component of NPQ, known as energy-dependent quenching (qE), occurs within minutes, but the site and mechanism of qE remain of great debate. Here, the chlorophyll fluorescence of Arabidopsis thaliana wild type (WT) plants was compared to mutants lacking all minor antenna complexes (NoM). Upon illumination, NoM exhibits altered chlorophyll fluorescence quenching induction (i.e. from the dark-adapted state) characterised by three different stages: (i) a fast quenching component, (ii) transient fluorescence recovery and (iii) a second quenching component. The initial fast quenching component originates in light harvesting complex II (LHCII) trimers and is dependent upon PsbS and the formation of a proton gradient across the thylakoid membrane (ΔpH). Transient fluorescence recovery is likely to occur in both WT and NoM plants, but it cannot be overcome in NoM due to impaired ΔpH formation and a reduced zeaxanthin synthesis rate. Moreover, an enhanced fluorescence emission peak at ~679?nm in NoM plants indicates detachment of LHCII trimers from the bulk antenna system, which could also contribute to the transient fluorescence recovery. Finally, the second quenching component is triggered by both ΔpH and PsbS and enhanced by zeaxanthin synthesis. This study indicates that minor antenna complexes are not essential for qE, but reveals their importance in electron stransport, ΔpH formation and zeaxanthin synthesis.     

Battling for Ribosomes: Translational Control at the Forefront of the Antiviral Response

In the early stages of infection, gaining control of the cellular protein synthesis machinery including its ribosomes is the ultimate combat objective for a virus. To successfully replicate, viruses unequivocally need to usurp and redeploy this machinery for translation of their own mRNA. In response, the host triggers global shutdown of translation while paradoxically allowing swift synthesis of antiviral proteins as a strategy to limit collateral damage. This fundamental conflict at the level of translational control defines the outcome of infection. As part of this special issue on molecular mechanisms of early virus–host cell interactions, we review the current state of knowledge regarding translational control during viral infection with specific emphasis on protein kinase RNA-activated and mammalian target of rapamycin-mediated mechanisms. We also describe recent technological advances that will allow unprecedented insight into how viruses and host cells battle for ribosomes.     

Ensuring objectivity by applying the Mauri Model to assess the post-disaster affected environments of the 2011 MV Rena disaster in the Bay of Plenty,New Zealand

The 2011 MV Rena grounding on Otāiti (Astrolabe reef) in the Bay of Plenty, New Zealand is considered to be New Zealand’s worst maritime environmental disaster and one of the most expensive shipwreck and oil spill salvage and recovery operations ever undertaken, with the clean-up currently costing in excess of $660 million (NZD) (Schiel et al., 2016; Beca, 2014). The resultant environmental impacts due to the fuel oil spilled and flotsam were also experienced anthropocentrically as economic, social and cultural impacts. The presence and consideration of impacts experienced by the indigenous groups of the impacted regions within the on-going recovery process is a major contributing factor to the uniqueness of this scenario internationally. The scale and complexity of impacts from this disaster is without precedent in New Zealand. The consideration of past and potential future impacts is especially significant in present times, with the resource consent application to leave the remnants of the wreck and associated debris in place on the reef and seabed, being granted on February 26 2016.The assessment builds on the methodology presented by Faaui et al. (2016) which established indicator sets for measuring impacts upon the mauri of the affected environments (post-Rena state) and assessing the state of the environment prior to the grounding (pre-Rena state). Using the sustainability indicator sets compiled previously by Faaui et al. (2016), the Mauri Model Decision Making Framework has been used to present a holistic assessment of the impacts of the disaster on the reef and surrounding ecosystems, from October 2011 (date of the grounding) to October 2015. These indicators have been expanded on, defining the threshold conditions for scoring the indicators within the Mauri Model. The impact assessment methodology has included a process that identifies the indicator scoring thresholds which ensures objectivity in the scoring of indicators, and therefore the impact assessment, allowing for repeatable and robust results.This assessment is the first use of the Mauri Model Decision Making Framework at this scale, providing a holistic assessment of the impacts experienced within the Rena affected regions in this post-Rena time period. This research leads directly into the post resource consent time period and the associated future impacts as a result of the consent and given consent conditions.