植物乳杆菌ST-ⅢproU基因簇的克隆、表达

分离自泡菜的植物乳杆菌ST-Ⅲ能够在盐浓度高达8%的环境下存活,其特有的质粒上存在一个与转运相容性溶质相关的proU基因簇,系统发育分析发现,proU基因簇与耐盐能力较高的戊糖乳杆菌IG1相应基因的相似性达100%,因此推测proU可能与植物乳杆菌ST-Ⅲ的耐盐能力相关。将proU及其包含的基因proX、proW、proV分别克隆到质粒pNZ8148上,并电转化到耐盐能力较低的乳酸乳球菌NZ9000中。重组菌株在添加3%NaCl和1mmol/L甜菜碱的化学成分确定培养基（CDM）中培养,以原始菌株乳酸乳球菌NZ9000（pNZ8148）为对照,测定耐盐能力。结果表明,各个基因均能在重组菌中表达,表达量与对照菌株相比至少提高了106倍,且重组菌株的耐盐能力均优于对照菌株,因此,proU与植物乳杆菌ST-Ⅲ耐盐能力直接相关。      

Lotus (Nelumbo nucifera Gaertn) plumule polysaccharide protects the spleen and liver from spontaneous inflammation in non-obese diabetic mice by modulating pro-/anti-inflammatory cytokine gene expression

A novel lotus plumule polysaccharide (LPPS) was administered to non-obese diabetic (NOD) mice for 15 weeks to evaluate the protective effects of LPPS on type 1 diabetes. After the 15-week feeding experiment, tumour necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10 expressions in the spleen, liver and kidney of the experimental mice were measured using enzyme-linked immunosorbent assay or real-time quantitative polymerase chain reaction assay. The results showed that LPPS significantly (p < 0.05) decreased the absolute weights of the enlarged spleens in the NOD mice in a dose-dependent manner, inhibited pro-inflammatory TNF-α and IL-6 cytokine production and decreased the secretion ratio of IL-6/IL-10 in splenocyte cultures. LPPS markedly decreased the relative expression of pro-/anti-inflammatory cytokine genes (TNF-α/IL-10 and IL-6/IL-10) in the livers of NOD mice. Our results suggest that LPPS protected the spleen and liver from spontaneous inflammation in NOD mice by modulating pro-/anti-inflammatory cytokine gene expression.     

Ultra Low-Dose Radiation: Stress Responses and Impacts Using Rice as a Grass Model

We report molecular changes in leaves of rice plants (Oryza sativa L. - reference crop plant and grass model) exposed to ultra low-dose ionizing radiation, first using contaminated soil from the exclusion zone around Chernobyl reactor site. Results revealed induction of stress-related marker genes (Northern blot) and secondary metabolites (LC-MS/MS) in irradiated leaf segments over appropriate control. Second, employing the same in vitro model system, we replicated results of the first experiment using in-house fabricated sources of ultra low-dose gamma (γ) rays and selected marker genes by RT-PCR. Results suggest the usefulness of the rice model in studying ultra low-dose radiation response/s.     

云南省牛乳中单核细胞增生李斯特氏菌的分布特征、耐药性及毒力研究

目的 分析云南省牛乳中单核细胞增生李斯特氏菌(Listeria monocytogenes)的分布特征、耐药性及毒力现状.方法 采集云南省主要奶产区牛乳样本,按照GB 4789.30—2016方法分离单核细胞增生李斯特氏菌疑似菌株,采用飞行时间质谱技术结合16S rDNA测序对疑似菌株进行鉴定;采用微量肉汤稀释法对分离...     

Nanoengineering Calcium Peroxide-Based Site-Specific Delivery Platform to Efficiently Activate the cGAS-STING Pathway for Cancer Immunotherapy by Amplified Endoplasmic Reticulum Stress

Currently, the understanding of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway's involvement in efficient immunotherapy mainly revolves around the role of mitochondria or nucleus modulation. Nonetheless, the role of endoplasmic reticulum (ER) stress in activating the cGAS-STING mechanism to boost immunity against tumors remains essentially unexplored. Herein, novel findings demonstrating that ER stress can be used as a strategy for stimulating the cGAS-STING pathway, thereby augmenting the immune response against cancer, are presented. To accomplish this objective, ER-targeting p-methylbenzene sulfonamide-tailored IR780 (p-780) is synthesized and it is loaded into CaO₂ nanoparticles, which are further functionalized with distearoyl phosphoethanolamine-polyethylene glycol（DSPE-PEG）-biotin to form PEG/CaO₂@p-780 NPs. The disruption of calcium homeostasis, coupled with the heightened levels of reactive oxygen species (ROS) mediated by p-780, along with hyperpyrexia, collectively contributes to the amplification of endoplasmic reticulum (ER) stress. This cascade of events effectively triggers the cGAS-STING pathway and, in parallel, facilitates the degradation of the programmed cell death 1 ligand 1 (PD-L1) protein. In addition, oxygen released through CaO₂ decomposition is expected to promote p-780–mediated phototherapy, while reversing the immunosuppressive tumor microenvironment associated with hypoxia. Furthermore, DSPE-PEG-biotin facilitates tumor site-specific drug delivery through active targeting mediated by the biotin receptor. Collectively, PEG/CaO₂@p-780 nanoparticles successfully activate systemic antitumor immunity by enhancing ER stress.     

Novel Virulence Factors Deciphering Klebsiella pneumoniae KpC4 Infect Maize as a Crossing-Kingdom Pathogen: An Emerging Environmental Threat

Klebsiella pneumoniae is not only a human and animal opportunistic pathogen, but a food-borne pathogen. Cross-kingdom infection has been focused on since K. pneumoniae was identified as the pathogen of maize, banana, and pomegranate. Although the pathogenicity of K. pneumoniae strains (from ditch water, maize, and human) on plant and mice has been confirmed, there are no reports to explain the molecular mechanisms of the pathogen. This study uncovered the K. pneumoniae KpC4 isolated from maize top rot for the determination of various virulence genes and resistance genes. At least thirteen plant disease-causing genes are found to be involved in the disruption of plant defense. Among them, rcsB is responsible for causing disease in both plants and animals. The novel sequence types provide solid evidence that the pathogen invades plant and has robust ecological adaptability. It is imperative to perform further studies on the verification of these KpC4 genes’ functions to understand the molecular mechanisms involved in plant–pathogen interactions.     

食品中克罗诺杆菌分离菌株生物被膜形成、耐药性及毒力基因检测

研究食品中克罗诺杆菌分离菌株的生物被膜形成、耐药性以及携带毒力基因情况。在成都市周边农贸市场和路边小摊采集食品样品129份,采用DFI 阪崎肠杆菌显色培养基分离克罗诺杆菌;通过16S rRNA序列比对分析鉴定分离菌株;采用试管法和微孔板法分析菌株生物被膜形成能力,同时研究温度对细菌成膜能力影响;采用纸片法检测分离菌株对18种抗生素的耐药性;采用PCR方法检测分离菌株携带cpa、hly、sip 和ompX毒力基因情况。结果发现从129份食品样本中共检出克罗诺杆菌43株,检出率为33.3%。43株克罗诺杆菌食品分离菌株的成膜率为90.7%,并且温度对细菌成膜影响明显。四种毒力基因中,ompX检出率为100%;cpa检出率为13.9%;hly检出率为11.6%;sip基因未检出。耐药表型检测发现43株克罗诺杆菌食品分离菌株对青霉素、克林霉素、万古霉素、苯唑西林和杆菌肽B的耐药率为100%,对利福平的耐药率达97.7%;对红霉素的耐药率为7%;对环丙沙星、庆大霉素、四环素、氯霉素、亚胺培南、磺胺甲恶挫、呋喃妥因、头孢西丁、链霉素、阿米卡星、氧氟沙星等100%敏感。本研究表明克罗诺杆菌食品分离菌株具有较好的形成生物被膜能力,对常见的抗生素耐药率较高,并且分离菌株携带一定的毒力基因,对食品安全造成潜在威胁。     

Evaluation of the Effects of Ag,Cu, ZnO and TiO2 Nanoparticles on the Expression Level of Oxidative Stress-Related Genes and the Activity of Antioxidant Enzymes in Escherichia coli,Bacillus cereus and Staphylococcus epidermidis

Although the molecular response of bacteria exposed to metal nanoparticles (NPs) is intensively studied, many phenomena related to their survival, metal uptake, gene expression and protein production are not fully understood. Therefore, this work aimed to study Ag-NPs, Cu-NPs, ZnO-NPs and TiO₂-NPs-induced alterations in the expression level of selected oxidative stress-related genes in connection with the activity of antioxidant enzymes: catalase (CAT), peroxidase (PER) and superoxide dismutase (SOD) in Escherichia coli, Bacillus cereus and Staphylococcus epidermidis. The methodology used included: the extraction of total RNA and cDNA synthesis, the preparation of primers for selected housekeeping and oxidative stress genes, RT-qPCR reaction and the measurements of CAT, PER and SOD activities. It was established that the treatment of E. coli and S. epidermidis with NPs resulted mainly in the down-regulation of targeted genes, whilst the up-regulation of genes was confirmed in B. cereus. The greatest differences in the relative expression levels of tested genes occurred in B. cereus and S. epidermidis treated with TiO₂-NPs, while in E. coli, they were observed under ZnO-NPs exposure. The changes found were mostly related to the expression of genes encoding proteins with PER and CAT-like activity. Among NPs, ZnO-NPs and Cu-NPs increased the activity of antioxidants in E. coli and B. cereus. In turn, TiO₂-NPs had a major effect on enzymes activity in S. epidermidis. Considering all of the collected results for tested bacteria, it can be emphasised that the impact of NPs on the antioxidant system functioning was dependent on their type and concentration.