Biologically inspired strategy for programmed assembly of viral building blocks with controlled dimensions

Facile fabrication of building blocks with precisely controlled dimensions is imperative in the development of functional devices and materials. We demonstrate the assembly of nanoscale viral building blocks of controlled lengths using a biologically motivated strategy. To achieve this we exploit the simple self-assembly mechanism of Tobacco mosaic virus (TMV), whose length is solely governed by the length of its genomic mRNA. We synthesize viral mRNA of desired lengths using simple molecular biology techniques, and in vitro assemble the mRNA with viral coat proteins to yield viral building blocks of controlled lengths. The results indicate that the assembly of the viral building blocks is consistent and reproducible, and can be readily extended to assemble building blocks with genetically modified coat proteins (TMV1cys). Additionally, we confirm the potential utility of the TMV1cys viral building blocks with controlled dimensions via covalent and quantitative conjugation of fluorescent markers. We envision that our biologically inspired assembly strategy to design and construct viral building blocks of controlled dimensions could be employed to fabricate well-controlled nanoarchitectures and hybrid nanomaterials for a wide variety of applications including nanoelectronics and nanocatalysis.     

Tobacco and alcohol as risk factors for oesophageal cancer in a high incidence area in South Africa

BackgroundThe Eastern Cape Province of South Africa, which includes the former Transkei has high rates of squamous cell oesophageal cancer (OC), thought to be caused mainly by nutritional deficiencies and fungal contamination of staple maize. A hospital-based case-control study was conducted at three of the major referral hospitals in this region to measure, among other suspected risk factors, the relative importance of tobacco smoking and alcohol consumption for the disease in this population.MethodsIncident cases (n = 670) of OC and controls (n = 1188) were interviewed using a structured questionnaire which included questions on tobacco and alcohol-related consumption. Odds ratios (ORs) with 95% confidence intervals for each of the risk factors were calculated using unconditional multiple logistic regression models.ResultsA monotonic dose-response was observed across the categories of each tobacco-related variable in both sexes. Males and females currently smoking a total of >14 g of tobacco per day were observed to have over 4-times the odds of developing OC (males OR = 4.36, 95% CI 2.24–8.48; females OR = 4.56, 95% CI 1.46–14.30), with pipe smoking showing the strongest effect. Similar trends were observed for the alcohol-related variables. The quantity of ethanol consumed was the most important factor in OC development rather than any individual type of alcoholic beverage, especially in smokers. Males and females consuming >53 g of ethanol per day had approximately 5-times greater odds in comparison to non-drinkers (males OR = 4.72, 95% CI 2.64–8.41; females OR = 5.24, 95% CI 3.34–8.23) and 8.5 greater odds in those who smoked >14 g tobacco daily. The attributable fractions for smoking and alcohol consumption were 58% and 48% respectively, 64% for both factors combined.ConclusionTobacco and alcohol use are major risk factors for OC development in this region.ImpactThis study provides evidence for further reinforcement of cessation of smoking and alcohol consumption to curb OC development.     

Burden of cancer attributable to tobacco smoking in member countries of the Association of Southeast Asian Nations (ASEAN), 2012

BackgroundCancer is an increasing problem in ASEAN (Association of Southeast Asian Nations). Tobacco use is a well-established risk factor for many types of cancers. Evidence on burden of cancer attributable to tobacco is essential to raise public and political awareness of the negative effects of tobacco on cancer and to be used to stimulate political action aims at reducing smoking prevalence in ASEAN member countries. The objective of this study was to estimate burden of cancer attributable to tobacco smoking in ASEAN, 2012.MethodsIn this study, smoking prevalence was combined with Relative Risks (RRs) of cancer to obtain Smoking Attributable Fractions (SAFs). Cancer incidence and mortality data among individuals aged 15 years and older were derived from GLOBOCAN 2012. Fourteen types of cancer were included in the analysis. Sensitivity analyses were conducted to examine the impact of the use of alternative RRs and the use of alternative prevalence of smoking in some countries.ResultsThe findings showed that tobacco smoking was responsible for 131,502 cancer incidence and 105,830 cancer mortality in ASEAN countries in 2012. In other words, tobacco smoking was accounted for 28.4% (43.3% in male and 8.5% in female) of cancer incidence and 30.5% (44.2% in male and 9.4% in female) of cancer mortality in ASEAN. When looking at the types of cancer, lung cancer showed the strongest association with tobacco smoking. Incidence of cancer and cancer mortality attributable to tobacco smoking varied by countries due to the differences in size of population, background risk of cancer, and prevalence of smoking in each country. According to the sensitivity analyses, RRs of lung cancer, pharynx cancer, and larynx cancer used in the estimates have significant impact on the estimates.ConclusionsAs about one-third of cancer incidence and mortality in ASEAN are attributable to tobacco smoking ASEAN member countries are strongly encouraged to put in place stronger tobacco control policies and to strengthen the existing tobacco control measure in order to effectively control cancer.     

The autophagy pathway participates in resistance to tomato yellow leaf curl virus infection in whiteflies

Macroautophagy/autophagy plays an important role against pathogen infection in mammals and plants. However, little has been known about the role of autophagy in the interactions of insect vectors with the plant viruses, which they transmit. Begomoviruses are a group of single-stranded DNA viruses and are exclusively transmitted by the whitefly Bemisia tabaci in a circulative manner. In this study, we found that the infection of a begomovirus, tomato yellow leaf curl virus (TYLCV) could activate the autophagy pathway in the Middle East Asia Minor 1 (MEAM1) species of the B. tabaci complex as evidenced by the formation of autophagosomes and ATG8-II. Interestingly, the activation of autophagy led to the subsequent degradation of TYLCV coat protein (CP) and genomic DNA. While feeding the whitefly with 2 autophagy inhibitors (3-methyladenine and bafilomycin A₁) and silencing the expression of Atg3 and Atg9 increased the viral load; autophagy activation via feeding of rapamycin notably decreased the amount of viral CP and DNA in the whitefly. Furthermore, we found that activation of whitefly autophagy could inhibit the efficiency of virus transmission; whereas inhibiting autophagy facilitated virus transmission. Taken together, these results indicate that TYLCV infection can activate the whitefly autophagy pathway, which leads to the subsequent degradation of virus. Furthermore, our report proves that an insect vector uses autophagy as an intrinsic antiviral program to repress the infection of a circulative-transmitted plant virus. Our data also demonstrate that TYLCV may replicate and trigger complex interactions with the insect vector.     

Changes in cigarette smoking behavior among breast cancer and unaffected women – A prospective study in the MARIE cohort

BackgroundSmoking cessation after a cancer diagnosis can reduce adverse cancer treatment outcomes. Whether a breast cancer diagnosis, a cancer commonly seen as unrelated to smoking cigarettes, motivates changes in smoking behavior is not fully understood. We aimed to compare long-term changes at three follow-up times of cigarette smoking behavior in women with breast cancer and baseline age- and region-matched unaffected women.MethodsWe used longitudinal data from the population-based case-control study MARIE (Mamma Carcinoma Risk Factor Investigation). Women with breast cancer (N = 3813) and unaffected women (N = 7341) aged 50–74 years were recruited from 2002 to 2005. Analyses on changes in smoking were based on data from those who also completed follow-up 1 in 2009–2012, follow-up 2 in 2014–2016 and follow-up 3 in 2020. Multinomial logistic regression for changes (quitting, stable, or start smoking) adjusted for age, study region, education, comorbidities, living situation, and follow-up time, was applied to examine the associations between breast cancer status and changes in smoking behavior.ResultsWomen with breast cancer had significantly higher odds than unaffected women of quitting smoking (OR = 1.38, 95 % CI: 1.01–1.89) and lower odds of returning to smoking (OR = 0.29, 95 % CI: 0.09–0.94) at follow-up 1, but were more likely to start or return to smoking at follow-up 2 (OR = 2.11, 95 % CI 1.08–4.15). No significant group differences were found for changes in smoking behavior at follow-up 3.ConclusionOur findings indicate that short-term changes in smoking behavior can be attributed to a breast cancer diagnosis, but that over time the effect diminishes and changes in smoking no longer differ between breast cancer and breast cancer-free women. To support smoking cessation and to prevent relapse, guidelines to address smoking in cancer care, as well as comprehensive tobacco treatment services, are needed.     

Genetic diversity and geographic distribution of Bemisia tabaci and Trialeurodes vaporariorum in Costa Rica

The tobacco whitefly Bemisia tabaci (Gennadius) cryptic species complex and of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) are extensively reported as destructive pests in vegetable crops worldwide. A survey was conducted in 2011 and 2012 to determine the occurrence and genetic diversity present in the populations of these whiteflies in the major vegetable production areas of Costa Rica. Insect samples were collected from sweet pepper (Capsicum annuum L.), tomato (Solanum lycopersicum L.), common bean (Phaseolus vulgaris L.) and weeds present in commercial crops either in open field or greenhouse conditions. PCR‐RFLP analysis of mitochondrial cytochrome c oxidase subunit 1 gene (mtCOI) sequences of 621 whitefly individuals confirmed the presence of the Mediterranean (MED) type of the B. tabaci and of T. vaporariorum in most sampled regions. Also, individuals of the Middle East‐Asia Minor 1 (MEAM1) type of the B. tabaci were observed in low numbers. Contingency analyses based on type of crop, geographical region, whitefly species, year of collection and production system confirmed that T. vaporariorum was the most frequent species in vegetable production areas in Costa Rica, both in greenhouses and in open fields. B. tabaci MED is likely spreading to new areas of the country, whereas B. tabaci MEAM1 was mostly absent or rarely found. Comparisons of mtCOI sequences from B. tabaci individuals revealed the presence of four B. tabaci sequence haplotypes (named MED‐i, MED‐ii, MEAM1‐i, MEAM1‐xviii) in Costa Rica, three of them identical to B. tabaci haplotypes previously reported in the Western Hemisphere and other parts of the world. Analysis of sequences of T. vaporariorum individuals revealed a more complex population with the presence of 11 haplotypes, two of which were identical to T. vaporariorum sequences reported from other countries.     

我国典型湿热地区变质烟用香精中腐败微生物的多样性分析

【背景】烟用香精是卷烟生产中的重要辅料,有些香精,特别是剩余的加料香精在运输和储存等过程中可能污染微生物,引起腐败变质发生。【目的】分析变质烟用香精中腐败微生物的群落多样性,确定引起加料香精变质的主要腐败微生物。【方法】采用稀释平板法,对我国典型湿热地区云南、福建和广西三地变质加料香精样品中的污染细菌、霉菌或酵母进行分离,分析其16S rRNA、ITS或26S rRNA基因序列,并通过反证试验确定引起变质的主要腐败微生物。【结果】所考察3个典型湿热地区变质加料香精存在不同程度的细菌、霉菌或酵母污染,其中细菌污染最为普遍。分离的76株污染细菌分布在2门4纲5目10科15属,细菌的群落多样性比较丰富,其中雷尔氏菌属(Ralstonia)、柠檬酸杆菌属(Citrobacter)、肠杆菌属(Enterobacter)及芽孢杆菌属(Bacillus)是优势菌群;9株霉菌分布在子囊菌门(Ascomycota)的3纲6属,每个属分离到1-2株霉菌;42株酵母分布在子囊菌门的6个属,其中毕赤酵母属(Pichia)、细枝钩酵母菌属(Wickerhamomyces)及酵母菌属(Saccharomyces)是优势菌群。云南和福建两地样品的细菌菌群组成明显多于广西,广西样品的霉菌菌群组成以及福建样品的酵母菌群组成均分别多于其余两地。反证试验结果显示,柠檬酸杆菌属、肠杆菌属、芽孢杆菌属、雷尔氏菌属和毕赤酵母属是引起烟用加料香精变质的主要腐败微生物。【结论】变质加料香精中污染微生物菌群组成及腐败微生物确定的研究将有助于我国湿热地区香精香料中污染微生物的控制和腐败变质的预防。     

Green fluorescent protein (GFP) as gene expression reporter and vital marker for studying development and microbe-plant interaction in the tobacco pathogen Phythphthora parasitica var. nicotianae

PEG-mediated transformation of protoplasts in the presence of lipofectin was achieved in Phytophthora parasitica var. nicotianae, an oomycete pathogen of tobacco. Using oomycete promoter and terminator sequences, a plant-adapted green fluorescent protein (GFP) was introduced into the microorganism. The data show for the first time that this eukaryotic gene reporter can be used in an oomycete, both as a quantitative reporter of gene induction and as a vital marker allowing the study of development of Phytophthora in vitro and in the host plant.