鼠伤寒沙门氏菌Ⅵ型分泌系统相关基因敲除及其功能特性

Ⅵ型分泌系统(T6SS)是大多数革兰氏阴性细菌中都存在的一种重要的分泌系统,能介导细菌与细菌之间以及细菌和宿主细胞之间的相互作用,溶血素共调节蛋白(Hcp)和缬氨酸甘氨酸重复蛋白G(VgrG)是组成T6SS穿刺装置的重要组分。但鼠伤寒沙门氏菌Ⅵ型分泌系统的Hcp与VgrG在该菌入侵宿主细胞及抗吞噬过程中发挥的作用尚不十分清楚。【目的】本研究旨在利用基因敲除技术构建的鼠伤寒沙门氏菌hcp及vgrg基因缺失株体外接种真核上皮细胞和巨噬细胞,并以其亲本株作为对照,以研究Hcp及VgrG在该菌粘附、侵入上皮细胞及抗吞噬过程中所发挥的作用。【方法】通过优化Red同源重组系统操作过程中各个条件,建立一套快速敲除鼠伤寒沙门氏菌Ⅵ型分泌系统相关基因的操作系统,成功构建鼠伤寒沙门氏菌CVCC541的hcp及vgrg单基因缺失株、双基因缺失株及三基因缺失株,并用Hela细胞接种试验和菌落计数试验,评估不同菌株的粘附和侵袭能力;用小鼠巨噬细胞RAW 264.7接种试验,评估不同菌株的抗吞噬能力。【结果】与亲本株CVCC541粘附侵袭Hela细胞相比,基因缺失株CVCC541Δvgrg、CVCC541Δhcp2Δvgrg和CVCC541Δhcp1Δhcp2Δhcp3的粘附率分别为17.17%±2.1%、14.73%±2.5%和82%±3.7%;CVCC541Δvgrg、CVCC541Δhcp2Δvgrg和CVCC541Δhcp1Δhcp2Δhcp3的侵袭率分别为7.05%±1.05%、6.21%±1.35%和87%±3.25%;与亲本株CVCC541在小鼠巨噬细胞RAW 264.7中的存活相比,基因缺失株CVCC541Δvgrg、CVCC541Δhcp2Δvgrg和CVCC541Δhcp1Δhcp2Δhcp3的存活率分别为15.67%±2.9%、14.47%±1.87%和56.12%±3.48%。【结论】鼠伤寒沙门氏菌Ⅵ型分泌系统VgrG和Hcp对该菌入侵细胞和抗吞噬方面具有重要作用,该研究为鼠伤寒沙门氏菌通过六型分泌系统与宿主细胞相互作用的机制研究奠定了基础。     

鼠伤寒沙门氏菌ybi H基因缺失株的构建及其生物学特性

【背景】鼠伤寒沙门氏菌(Salmonella typhimurium)是一种重要的人兽共患病原菌,能够引起多种食源性疾病。ybiH基因在鼠伤寒沙门氏菌中的生物学功能尚未确定。【目的】构建鼠伤寒沙门氏菌ybiH基因的缺失株和回补株,研究ybiH基因在鼠伤寒沙门氏菌中的生物学功能。【方法】采用λ-Red同源重组系统构建鼠伤寒沙门氏菌CVCC541 ybiH基因缺失株STΔybiH,同时构建该基因缺失株的回补株STΔybi H/pybiH,并对缺失株STΔybiH的生长特性、运动性、生化特性和毒力情况等生物学特性进行比较分析。【结果】与标准株和回补株相比,缺失株STΔybiH生长速率略快,而其运动性、生化特性、耐药性均无明显差别。但是,ybiH基因的缺失明显提高了鼠伤寒沙门菌对IEC-6细胞和RAW264.7细胞的黏附力和侵袭力,qRT-PCR实验结果显示,缺失株中Inv H基因的表达量明显提高,表明ybiH基因的缺失使鼠伤寒沙门氏菌的侵袭力也有所提高。此外,在胞内存活实验中,标准株与缺失株在胞内的增长率变化不明显,表明ybiH基因的缺失对沙门氏菌在RAW 264.7细胞中存活的影响不大。【...     

鼠伤寒沙门菌baeSR基因缺失株的构建及其对抗生素敏感性分析

【背景】沙门菌的多重耐药现象日渐严重,对其耐药机理的研究尤为迫切,双组分系统与细菌耐药性密切相关。【目的】构建鼠伤寒沙门菌baeSR基因缺失株及回补株,探究双组分系统BaeSR对鼠伤寒沙门菌耐药性的影响。【方法】以鼠伤寒沙门菌体外诱导耐药株CR为研究对象,通过自杀质粒p LP12介导的同源重组方法,以氯霉素抗性标记和阿拉伯糖诱导的致死基因vmt进行正、反向双重筛选,获得基因缺失株CRΔbaeSR,并将重组表达质粒pBAD-baeSR转化于CRΔbaeSR构建回补株CR CΔbaeSR。采用微量肉汤稀释法测定11种常见代表药物对野生株、缺失株及回补株的最小抑菌浓度(Minimum inhibitory concentration,MIC),并测定3株菌的生长曲线、运动性及生物膜形成能力。【结果】与野生株相比,环丙沙星(CIP)、恩诺沙星(ENR)、沙拉沙星(SAR)、头孢噻呋(CEF)、庆大霉素(GEN)、阿米卡星(AMK)、安普霉素(APR)对缺失株的MIC值有所下降;缺失株的生长速率稍显缓慢,且最终浓度也相对较低,但并无统计学上的显著差异(P0.05);缺失株的运动性(P0.05)及生物膜形成能力(P0.01)均显著下降。【结论】鼠伤寒沙门菌baeSR基因缺失后,可通过影响其运动性及生物膜形成能力而对抗生素的敏感性产生影响。     

鼠伤寒沙门菌SL1344株环化腺苷酸合成酶缺失株平衡致死系统的构建及其雏鸡免疫保护试验

摘要:【目的】为构建鼠伤寒沙门菌环化腺苷酸合成酶缺失株平衡致死系统,并对其生物学特性进行检测。【方法】以鼠伤寒沙门菌SL1344Δcya株为亲本株,利用重组自杀性质粒(pREΔasd)介导的同源重组技术,经两步法缺失并筛选asd基因缺失株(SL1344Δcya Δasd)。将含asd基因且无抗性的pYA3493质粒电转化至缺失株SL1344ΔcyaΔasd,构建重组菌株SL1344ΔcyaΔasd (pYA3493)。【结果】试验结果表明,重组菌株SL1344ΔcyaΔasd(pYA3493)生化特性和生长速度与参考株SL1344相比差异较大,与亲本株SL1344Δcya基本一致,SL1344ΔcyaΔasd(pYA3493)失去了利用麦芽糖、乳糖、山梨醇等碳源的能力,也不能分解H2 S、半乳糖和鼠李糖,但仍保留了利用葡萄糖的能力。对1日龄雏鸡攻毒试验表明,SL1344ΔcyaΔasd(pYA3493)毒力较参考株SL1344降低了约104倍。免疫保护试验显示,1日龄雏鸡免疫SL1344ΔcyaΔasd(pYA3493)后第17天,利用鼠伤寒沙门菌参考株攻毒,保护率为62.5%。【结论】鼠伤寒沙门菌SL1344株环化腺苷酸合成酶缺失株平衡致死系统构建成功,且具有较好的免疫保护性,为深入研究以鼠伤寒沙门菌为载体的口服疫苗奠定基础。     

鼠伤寒沙门菌rtsB基因缺失株的构建及其生物学特性

【背景】鼠伤寒沙门菌(Salmonella typhimurium)是一种重要的人畜共患病原菌,严重危害养殖业及人类健康。调控蛋白在病原菌的生存及感染过程中发挥重要作用。【目的】构建鼠伤寒沙门菌调控基因rtsB缺失株和互补株,分析调控蛋白RstB对鼠伤寒沙门菌生物学特性和致病性的影响。【方法】利用Red同源重组的方法构建鼠伤寒沙门菌SAT52的rtsB基因缺失株,并利用互补质粒构建互补株。然后比较分析野生株SAT52、缺失株?rtsB和互补株C?rtsB的生长特性、运动性、生物被膜形成能力、黏附入侵能力、胞内存活能力及致病性的差异。【结果】缺失rtsB基因不影响SAT52的生长速度,但导致运动能力增强,生物被膜形成能力减弱。细胞感染试验结果表明,rtsB基因有助于鼠伤寒沙门菌对Hela细胞的黏附入侵及RAW264.7细胞内的存活。动物试验结果表明rtsB基因缺失显著降低鼠伤寒沙门菌的致病力。【结论】rtsB基因在鼠伤寒沙门菌感染过程中发挥重要作用,可为阐释鼠伤寒沙门菌的致病机制提供参考。     

假定调控蛋白STM14_3514可降低鼠伤寒沙门菌对上皮细胞的侵袭力

【目的】研究鼠伤寒沙门菌致病岛1(SPI-1)内部的假定调控蛋白STM14_3514的功能及其作用机制。【方法】以鼠伤寒沙门菌模式菌株ATCC 14028为亲本株,构建了STM14_3514基因的缺失突变体及互补菌株,通过小鼠实验、细胞侵袭实验、Western blot及实时荧光定量PCR(q RT-PCR)等实验技术,深入研究了STM14_3514基因对鼠伤寒沙门菌致病过程的影响。【结果】STM14_3514突变提高了细菌对小鼠的致病能力,突变体在小鼠肠道、肝和脾中的定殖能力均增强;细胞实验揭示,突变体致病力提升主要由于STM14_3514突变能显著增强细菌对上皮细胞的侵袭力(2倍,P0.05)。q RT-PCR及Western blot分析表明,STM14_3514显著抑制SPI-1内部主要调控因子hil A及侵袭相关基因的表达。此外,STM14_3514对hil A的抑制由Hil C介导。【结论】STM14_3514是鼠伤寒沙门菌SPI-1内部的负调控因子,能通过Hil C抑制hil A及SPI-1其他入侵基因的表达,该基因的生物学意义可能与细菌进入细胞后对SPI-1的负调控相关。     

kpsE和kpsD双基因缺失显著降低肠道外致病性大肠杆菌的毒力

【目的】探究荚膜对肠道外致病性大肠杆菌致病作用的影响。【方法】选取负责荚膜多糖转运的基因kpsE和kpsD,利用λRed重组系统构建APEC E058和UPEC U17荚膜缺失株E058ΔkpsED和U17ΔkpsED,并通过一系列的体内及体外试验对其生物学特性及致病性进行研究。【结果】双基因缺失株的生长速度较野生株没有明显差异,但缺失株抗血清补体杀菌能力和抗鸡巨噬细胞HD-11细胞吞噬能力显著下降。1日龄雏鸡LD50致病性试验结果显示,缺失株E058ΔkpsED和U17ΔkpsED对鸡失去致病力,而回复株毒力恢复至野生株水平;35日龄SPF鸡体内动态分布和竞争试验显示ΔkpsED缺失株在鸡体内定殖能力和竞争性生长能力显著下降,表明kpsED双基因的缺失能显著降低APEC E058和UPEC U17的致病力。【结论】荚膜与肠道外致病性大肠杆菌的致病性相关,是其重要的毒力因子。     

基于串联质谱标签法和平行反应监测技术的氟喹诺酮耐药沙门菌蛋白质组学分析

【背景】随着沙门菌对氟喹诺酮类药物的耐药性不断增强,对其耐药机理的研究显得尤为迫切和重要,蛋白质组学分析将为沙门菌的耐药机理研究提供新的靶点和方向。【目的】对鼠伤寒沙门菌诱导获得耐药性前后进行蛋白质组学分析,为深入研究沙门菌耐药机理奠定基础。【方法】用环丙沙星对鼠伤寒沙门菌ATCC13311进行耐药性诱导,利用串联质谱标签法(Tandem mass tag,TMT)对其耐药性进行差异蛋白的筛选和生物信息学分析,并选取15个差异蛋白进行平行反应监测(Parallel reaction monitoring,PRM)靶向蛋白验证。【结果】筛选出318个差异表达蛋白,其中上调159个,下调159个,涉及的KEGG通路主要包括细菌趋药性、ABC转运蛋白、双组分系统等;PRM定量到13个验证蛋白且变化趋势与TMT一致。【结论】通过TMT定量结合PRM靶向验证对鼠伤寒沙门菌耐药前后进行蛋白质组学分析,筛选出多个差异蛋白和代谢通路,包括外排泵相关蛋白、外膜蛋白、双组分相关蛋白及通路、细菌趋化性相关蛋白及通路等,为沙门菌氟喹诺酮类耐药机理的深入研究奠定了基础。     

禽大肠杆菌、肠炎、鼠伤寒、鸡白痢及鸡伤寒沙门菌多重PCR方法的建立及应用

【背景】大肠杆菌病和沙门菌病是最常见的家禽细菌性疾病,给养禽业造成严重经济损失。另外,禽大肠杆菌和沙门菌也是重要的人畜共患病原菌,可通过禽类及其产品传播给人类,对人类健康造成严重威胁。加强禽大肠杆菌和沙门菌的快速鉴别检测,对养禽业和公共卫生都具有重要意义。【目的】建立禽大肠杆菌、肠炎沙门菌、鼠伤寒沙门菌、鸡白痢沙门菌和鸡伤寒沙门菌的多重PCR检测方法。【方法】通过比较分析确定禽致病性大肠杆菌、肠炎沙门菌、鼠伤寒沙门菌、鸡白痢沙门菌和鸡伤寒沙门菌的特异靶标基因,设计5对特异性引物,通过条件优化建立多重PCR方法,分析该多重PCR方法的特异性、敏感性及可靠性。【结果】该方法能特异性地鉴定禽致病性大肠杆菌、肠炎沙门菌、鼠伤寒沙门菌、鸡白痢沙门菌和鸡伤寒沙门菌,每个PCR反应的最低检出限分别为103 CFU细菌和100 pg基因组DNA。临床分离菌株检测显示,多重PCR与传统血清学方法结果一致。【结论】建立的多重PCR方法能够快速鉴别禽致病性大肠杆菌和不同血清型沙门菌,对禽大肠杆菌病和沙门菌病的流行病学调查及临床检测具有重要意义。     

肠炎沙门菌肽脯氨酰顺反异构酶SlyD的基因敲除、表达及酶学特征

【目的】以肠炎沙门菌肽脯氨酰顺反异构酶SlyD为对象,构建基因缺失株及表达纯化该蛋白,为研究其在肠炎沙门菌致病性与应激等方面的作用奠定基础。【方法】参考Gen Bank登录的肠炎沙门菌基因组序列设计用于slyD基因敲除及原核表达的特异引物,运用自杀质粒介导的同源重组技术对肠炎沙门菌C50041 slyD基因进行敲除,构建C50041ΔslyD缺失株;原核表达SlyD蛋白,通过α-糜蛋白酶耦联法对其PPIase活性进行测定;利用生物信息学相关软件,分析SlyD蛋白的氨基酸序列及功能域。【结果】PCR鉴定与测序结果证明成功构建了肠炎沙门菌C50041ΔslyD缺失株,其生长特性与野生株基本一致;SDS-PAGE及PPIase活性分析表明,获得了具有生物活性的可溶性SlyD蛋白;生物信息学分析显示SlyD蛋白由FKBP样肽脯氨酰顺反异构酶结构域、分子伴侣功能域和金属结合区域3个功能区域组成。【结论】成功获得了肠炎沙门菌C50041ΔslyD缺失株和具有PPIase活性的重组SlyD蛋白。     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

A molecular phylogeny of Hebeloma species from Europe

In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

New species of Peruvian Orchidaceae III

Sixteen new species are proposed in the generaAckermania, Dressleria, Epidendrum, Maxillaria, Oncidium, Rodriguezia, Sigmatostalix, andTrigonidium. All new species are illustrated.Maxillaria vittariifolia L. O. Williams is newly recorded for Peru. A key is provided forTrigonidium of Peru.Trigonidium loretoense Schltr. andT. peruvianum Schltr. are lectotypified.     

Interaction of Synthetic Analogues of Natural Chalcones and Flavones with Guanidine

The reaction of chalcones and flavones with guanidine in ethanol results in 2-(2-aminopyrimidinyl-4)-phenols.     

Demographic characteristics of an intertidal bay goby (Lepidogobius lepidus)

Synopsis In a fourteen month study (May 1976 – June 1977) I examined the following characteristics of an intertidal bay goby (Lepidogobius lepidus) in Morro Bay, California, U.S.A.: annual and seasonal patterns of abundance, age composition and growth rates, survivorship and mortality patterns, and the reproductive cycle for female gobies. Fishes were collected with the aid of quinaldine and otoliths and ovaries removed. Age and growth rates were estimated from otolith annuli using a back calculation formula and a Brody-Bertalanffy growth curve. Mortality rates were derived using the methods of Heincke (1913), Robson & Chapman (1960), mean age, and a catch curve (Ricker 1975). A gonad index was used to describe the annual reproductive cycle. Results indicated that abundance fluctuated seasonally and that these fluctuations appeared to be caused by reproductive emigrations. Bay gobies reached an age of 7+ and a standard length of 87 mm. Growth was relatively constant (6 mm yr⁻¹) until age 5, at which point it began to decline. The mean rates of survivorship, mortality, and instantaneous mortality were 0.75, 0.25, and 0.29 respectively. Mortality rates for individual age classes ranged from 0.13 to 0.51 and increased with age. This stock appears to reproduce mainly during the winter.