Acanthamoeba Interaction with Extracellular Matrix Glycoproteins: Biological and Biochemical Characterization and Role in Cytotoxicity and Invasiveness

ABSTRACT. Acanthamoeba are free-living amoebae that are dispersed in most environments. Occasionally, Acanthamoeba cause serious human infections, such as keratitis and encephalitis. During the infection process, amoebic adhesion to, and degradation of, host cells and their extracellular matrix (ECM) appear to be important requirements. We examined the interaction of Acanthamoeba with the ECM, and related this event to host cell destruction and tissue invasion. Pathogenic Acanthamoeba culbertsoni differentially attached on the ECM glycoproteins laminin-1, collagen-I, and fibronectin, as compared with non-pathogenic Acanthamoeba astronyxis . Binding to collagen-I and laminin-1 induced A. culbertsoni to become flattened and elongated. Because attachment on laminin-1 was higher in A. culbertsoni , laminin-1 was chosen for further analysis. A 55-kDa laminin-binding protein was identified in pathogenic amoebae, but it was not found in non-pathogenic amoebae. No differential cytotoxicity against distinct cell types was observed between A. culbertsoni incubated with or without ECM. On the other hand, binding on collagen-I or matrigel scaffolds induced a differential effect where A. culbertsoni invaded collagen-I matrices more rapidly. These results indicate that ECM recognition, as an antecedent to tissue invasion, may be a trait characteristic of pathogenic Acanthamoeba .     

First Record of the Peritrich Trichodina diaptomiBasson and Van As, 1991 (Protozoa: Ciliophora) on a South American Calanoid Notodiaptomus deitersi (Poppe, 1890) (Crustacea: Copepoda)

ABSTRACT. The ciliate Trichodina was recorded on the calanoid Notodiaptomus deitersi in a shallow, eutrophic reservoir, located in the centre‐west of Brazil. The species was confirmed as Trichodina diaptomi, a species widely distributed in Europe, Africa, Asia and Australia. It was observed moving freely over the carapace of the copepod, and using its adhesive disc. This is the first record for the species in the Americas.     

Paravahlkampfia francinae n. sp. Masquerading as an Agent of Primary Amoebic Meningoencephalitis

ABSTRACT. Paravahlkampfia francinae n. sp., a new species of the free-living amoeba genus Paravahlkampfia , designated as CDC:V595, was isolated from the cerebrospinal fluid of a patient with headache, sore throat, and vomiting, typical symptoms of primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri . The isolate grew at 33 °C, 37 °C, 40 °C, and 42 °C and destroyed mammalian cell cultures. However, it did not kill young mice upon intranasal inoculation. P. francinae does not produce flagellates and does not grow on agar plates coated with Gram-negative bacteria such as Escherichia coli , the usual food source of Paravahlkampfia ustiana , the type species of the genus. The trophozoite at light microscopy exhibited eruptive locomotion and possessed a single vesicular nucleus. Ultrastructurally, the trophozoites had numerous mitochondria with discoidal cristae but did not have a Golgi apparatus. The trophozoites differentiated into cysts after consuming most of the monolayer. The cyst had an inner well-differentiated endocyst and an outer thin, wrinkled, and wavy ectocyst with no pores. During excystation trophozoites ruptured the cyst wall and emerged from the cysts. A unique feature seen in the cysts was the presence of bacterial endosymbionts, both in the endoplasm and within the cyst wall. Full-length sequencing analysis of the 18S and 5.8S RNA genes of P. francinae showed that they were distinct from those of other Paravahlkampfia species. The patient recovered within a few days indicating that some of the previously reported cases of PAM that survived may have been due to P. francinae .     

常绿阔叶树种栲树开花物候动态及花的空间配置

 基于定株观测和随机枝取样法,对浙江天童常绿阔叶林内栲树（Castanopsis fargesii）的开花物候动态及其雌花、雄花的空间配置进行了研究。结果表明：在栲树的生殖枝上,并非所有的芽都分化、萌发生成花序,栲树花芽的分化和发育集中在一级生殖枝上。生殖枝上花芽的分化与该枝的空间位置密切相关。栲树花期明显晚于春季的展叶期,与叶片生长时间重叠。盛花期集中于5月下旬,约持续8 d左右,属于同步发生的花期。栲树雄花序的数量明显高于雌花序,雄花序约占花序总数的77.88%,雌花序仅占22.12%。大量雄花和花粉的存在是保证雌花接受花粉和完成受精的基础。花序在植冠层中的空间配置明显不同：在同一植冠内,向阳面和背阴面生殖枝上芽萌发成花序的比率存在明显差异(p<0.01),阳面生殖枝上顶芽萌发成花序的比率高于阴面生殖枝的比率,并且,阳面的每个生殖枝上平均花序数和雄花数量均高于阴面生殖枝,花序的分化和发育与枝系的生长发育状况有密切关系。     

Effect of heparin on apoptosis in human nasopharyngeal carcinoma CNE2 cells

lwTRODUCTIONHeparin is a polysuifated glycosaminoglycanwith a high negatbe charge. Heparin is synthesized in various tissues, especially in the lha, 1ung,and gut. In addition to its allti-coagulant activityheparin is known to have anti-hypertensive[1], auiinflammatory[2], and antiproliferative effects. Be-sides, heparin inhibits leukocyte rol1ing and its adhe-sion to endothelium, its aggregation, degranulation,and the generation of superoxide anion by actndingncotrophils[3~51. Heparin and …     

祁连山青海云杉林地土壤水分特征研究

通过对祁连山青海云杉林地土壤水分含量及主要影响因子的测定,结果表明,青海云杉林地土壤具有容重低、入渗率高、土壤水分含量垂向分布受降水影响明显等特征,灌木-青海云杉林、苔藓-青海云杉林和草地(对照)平均容重分别为0．522、0．641、0．874g·cm^-3．土壤初渗率分别为6．0、21．0、2．5mm·min^-1,稳渗率分别为3．98、11．2、0．5mm·min^-1．苔藓-青海云杉林地土壤可划分为4层：水分活跃层(0～30cm)、水分调节层(30～60cm)、水分传输层(60～80cm)和蓄水层(80ClTI以下),各层土壤贮水量分别为3．30、3．17、2．80和2．83mm·cm^-1．灌木-青海云杉林可分为3层：水分稳定层(0～30cm)、水分活跃层(30～60cm)和水分传输层(60cm以下),各层土壤贮水量分别为3．98、3．65、3．48mm·cm^-1．两种林地土壤水分含量的季节变化受降水影响较大,相比而言,苔藓．青海云杉林地入渗率更高,有较明显的蓄水层,水分传输能力更强,而灌木-青海云杉林地贮水能力更强．     

浙江天童国家森林公园微地形与植被结构的关系

植物群落的本质特征之一是群落中的植物和环境之间存在一定的相互关系。丘陵地区的地形由各种微地形单元构成,这些微地形单元在空间上的分化提供的异质化的生境导致了区域丰富的物种和群落多样性的形成。选择浙江东部低山丘陵地区具有典型代表意义的天童国家森林公园,在地形识别的基础上,结合详细的植被调查,分析了不同微地形单元物种组成及其林分结构的变化。结果表明,基于物种组成相似性,7个微地形单元可以归为2组,与通过侵蚀前线划分结果一致。依据物种在这2个小尺度地形单元的分布格局,可以划分出3个特征种组,即上部坡面分布型、下部坡面分布型和无统计偏差型。壳斗科、山茶科、冬青科和山矾科常绿物种是构成上部坡面植被的主要成分,而榆科、槭树科、胡桃科和漆树科等的落叶种及樟科常绿种则是构成下部坡面植被的主要成分。下部坡面各微地形单元的林分垂直构造比上部坡面复杂,由榆科、槭树科、胡桃科和漆树科生境先锋种形成的明显超高层以及超大个体的存在是其显著特征。但其密度低于上部坡面微地形单元。上部坡面的顶坡和谷头凹地明显缺乏乔木层的存在。侵蚀前线是丘陵地区不同生境最重要的划分界限,由其切分的上部坡面和下部坡面是评价物种组成和林分结构的两大基本功能区域。     

基于钙黄绿素的荧光分光光度法测定谷胱甘肽

目的：基于钙黄绿素的荧光分光光度法建立一种测定谷胱甘肽的新方法。方法：在pH=8.0介质中,铜（Ⅱ）与钙黄绿素配位引起荧光猝灭,由于谷胱甘肽与铜（Ⅱ）的亲和力很强,可从钙黄绿素-铜离子的络合物中夺取铜离子而使钙黄绿素游离出来使荧光强度得以恢复,荧光恢复的程度与加入谷胱甘肽的浓度在一定浓度范围内成线性。结果：据此建立了一种测定谷胱甘肽的新方法,该方法的线性范围为2.0×10-6～1.4×10-5mol.L-1,F=8.1964C＋196.43,检测限为1.0×10-6mol/L。结论：用此法测定谷胱甘肽简便快速,灵敏度高。     

非缺陷性网状内皮组织增生病毒的血清学区别

26株来自各种禽的网状内皮组织增生病毒(REV),用多克隆的抗REV鸡血清做交叉中和试验,用REV、T株,Coo1株所制备的单克隆抗体做免疫荧光试验,比较这些毒株之间的抗原关系,从交叉中和试验结果看,它们之间的抗原关系十分接近,可以认为同属于单一血清型;但也确实存在微小差异,因此又可以将它们分为三个血清亚型,这一结果巳被单克隆抗体检验所证实。