中国云南人间鼠疫流行区印鼠客蚤在其主要宿主黄胸鼠体表的空间分布格局研究(英文)

中国云南人间鼠疫流行区的主要鼠疫传播媒介是印鼠客蚤。其主要宿主为黄胸鼠。应用Iwao方法及其随机偏离度检验 ,对印鼠客蚤在黄胸鼠的不同个体间的空间分布格局进行了研究。根据Iwao方法建立的印鼠客蚤直线回归模型为 :M =α βM =4 0 0 6 4 2 0 153M ,其中的α和 β均明显高于空间分布判定的界线值 0和 1,经随机偏离度检验 ,F =4 5892 ,P <0 0 5。结合α ,β值及随机偏离度检验结果 ,印鼠客蚤在其主要宿主黄胸鼠体表的空间分布型被判定为聚集型分布。印鼠客蚤这种聚集型分布意味着该蚤的个体分布不均匀 ,而是在宿主动物体表形成大小不等的聚集蚤群。印鼠客蚤在黄胸鼠不同个体间的这种不均匀分布提示 :即使接触同一种染疫鼠类动物 ,因鼠体蚤分布极不均匀 ,其传播机会是不均等的。     

二齿新蚤和方形黄鼠蚤松江亚种侵袭与离开宿主习性的实验研究

本文对二齿新蚤和方形黄鼠蚤松江亚种侵袭与离开宿主的习性进行了实验研究,结果：(1)蚤攻击宿主距离平均在2cm以内,最大攻击距离不超过10cm。在有效侵袭范围内,蚤与宿主距离近时较距离远时吸血蚤数增多。(2)蚤对宿主的侵袭程度雌蚤大于雄蚤,繁殖蚤大于新羽化蚤,二齿新蚤大于方形黄鼠蚤松江亚种,对小白鼠大于对达乌尔黄鼠。(3)宿主死后一定时间内,仍有部份蚤侵袭其尸体。 死亡时间越长侵袭蚤数越少,呈logY=a-blogX型曲线。(4)蚤离开宿主时间呈偏态分布,温度越高偏态分布越明显。蚤离开死鼠和离开活鼠所需时间很接近。 二齿新蚤和方形黄鼠蚤松江亚种离开宿主时间几乎相同。二种蚤离开宿主平均时间与环境温度呈负相关,且呈曲线关系。     

黄鼠体蚤和宿主密度的年间动态关系

根据内蒙古自治区正镶白旗乌宁巴图苏木1981-1993年达乌尔黄鼠Citellus dauricus密度和体蚤指数监测资料进行分析,得到如下结果。共检体蚤10种,其中方形黄鼠蚤蒙古亚种Citelloilus tesquorum mongoJicus(72.38%)和光亮额蚤Fronto Psylla luculenta(18.03%)分别为优势和次优势蚤种,阿巴盖新蚤Neopsylla abagaitui、二齿新蚤Neopsylla bidentatifor-mis为常见种,余为少见种。宿主密度与蚤指数均呈指数增长,鼠密度与蚤指数的关系是极为显著的(P<0.0001),关系为鼠密度＝exp(-0.6206十0.1989t),蚤指数＝1.6109+0.8997(鼠密度)。方形黄鼠蚤蒙古亚种比例的高低显著地影响体蚤的多样性和均匀性.宿主 密度与染蚤率呈正相关关系(P相似文献   

蚤类在宿主体表的分布及温度和蚤数的关系

本文研究了方形黄鼠蚤松江亚种Citellophilus tesquorum sungaris和二齿新蚤Neopsylla bidentatiformis在小白鼠体表的分布及环境温度和体表蚤数的关系.结果证明,在各种温度下,鼠背部蚤数均多于腹部.5℃时,鼠前部蚤数多于后部;10—20℃时,前部与后部蚤数相近;25—40℃时,后部蚤数多于前部.鼠后背部蚤数随温度升高而增多,前腹部蚤数随温度升高而减少;温度越高二者之差越大,说明温度越高蚤越向后背部集中.鼠体蚤数较少时,背部与腹部,前部与后部,蚤数差别明显;鼠体蚤数过多时,各部位蚤数无大差别.     

蚤状蚤的生长和生殖

在３５、３０、２５℃３种温度下观察了蚤状（Ｄａｐｈｎｉａｐｕｌｅｘ）的生长和生殖。其生长随年龄的增加而逐渐减慢，寿命因温度升高而缩短。在２５℃条件下，蚤状寿命、产仔数和产仔率明显高于其他组，其平均寿命为６５．５天，累计产仔总数为４０１．６个，产仔率为２１．２２。     

二齿新蚤的吸血活动

本文在实验室内研究了二齿新蚤吸血活动与环境温度、蚤龄、性别的关系。实验证明,幼蚤吸血最适温度为25℃左右,该温度下吸血率最高;成蚤在各种温度下,吸血率均接近100%。成蚤吸血率高于幼蚤。幼蚤雌蚤吸血率高于雄蚤,成蚤吸血率雄雌均接近100%。蚤吸血量与吸血时温度无关,威蚤吸血量大于幼蚤。雌蚤吸血量大于雄蚤。蚤的血液消化速度,高温时较低温时为快。在温度25℃以下时,成蚤消化速度较幼蚤为快;30℃以上时,成蚤与幼蚤消化速度相近。消化速度与性别无关。     

青海多毛蚤属一新种记述（蚤目：多毛蚤科）

本文报道多毛蚤属Ｈｙｓｔｒｉｃｈｏｐｓｙｌｌａ的一新种,文贞多毛蚤Ｈ．ｗｅｎｚｈｅｎｉ ｓｐ．ｎｏｖ．,新种与近缘种圆凹多毛蚤Ｈ．ｒｏｔｕｎｄｉｓｉｎｕａｔａ,多刺多毛蚤Ｈ．ｍｕｌｔｉｄｅｎｔａｔａ和尼泊尔的Ｈ．ｓｙｎａｐｔｉｃａ接近而又有明显区别,新种采自青海省同德县的斯氏水麝鼠句Ｃｈｉｍａｒｒｏｇａｌｅ ｓｔｙａｎｉ,标本存青海省地方病防治研究所。     

黄鼠洞干蚤和宿主密度的年间动态关系

根据内蒙古自治区正镶白旗乌宁巴图苏木1981～1993年达乌尔黄鼠Citellus dauriCUS密度和洞干蚤指数监测资料进行分析,得到如下结果。共检洞干蚤9种,其中方形黄鼠蚤蒙古亚种Citellophilus tesquorum mongolicus (66.0%)为优势蚤种,光亮额蚤Frontopsylla lu-culenta(23.6%)为次优势蚤种,阿巴盖新蚤Neopsylla abagaitui和二齿新蚤N。Bidentatifor-mis为常见种,余为少见种。鼠密度与洞干蚤指数关系显著(PPP<0.05),关系为洞干蚤指数=0.2709+0.0504体蚤指数。洞干蚤和巢蚤指数的关系是显著的(P<0.07),关系为洞干蚤指数＝0.27652+0.00348巢蚤指数。三种蚤指数之间有如下近似 关系：巢蚤指数：体蚤指数：洞干蚤指数：100：10：1。     

四川黑水多毛蚤属一新种（蚤目：多毛蚤科）

四川黑水多毛蚤属一新种（蚤目：多毛蚤科）李贵真,刘连珠贵阳医学院生物学教研室,贵州省贵阳市５５０００４第三军医大学寄生虫学教研室,四川省重庆市６３００００关键词蚤目,多毛蚤科,多毛蚤属,新种四川我们在整理早年所采蚤类标本时,发现采自四川黑水的多毛蚤１...     

大理苍山洱海自然保护区山地蚤类区系与生态的研究

１９９２－１９９７年,对大理苍山洱海自然保护区山地蚤类进行了垂直分布的调查研究,共采获蚤类５科２１属３９种（亚种）３２４１头,并对以苍山为主体的山地各主要生态环境蚤类的群落结构,物种丰富度,物种多样性,均匀度和生态优势度进行了测定和比较,分析蚤类及其宿主动物的分布特点和自然环境因素后认为,在苍山所获３９种蚤类中有１６种（占４１．０３％）属东洋界种类,２１种（占５３．８４％）,属古北界种类,２种属广     

北方几种蚤类侵袭寄主的研究和斧形盖蚤叮人试验

本文研究了二齿新蚤和方形黄鼠蚤松江亚种对寄主的侵袭活动,包括活寄主与死寄主被侵袭情况比较,寄主体表蚤数与环境温度的关系,以及与蚤同寄主接触时间的关系。还研究了达乌尔黄鼠和达乌尔鼠兔寄生蚤在一日不同时间里的数量变化。并观察了斧形盖蚤叮人情况。     

Immunity,antigenic heterogeneity,and aggregation of helminth parasites

Empirical studies of helminth parasites reveal that the distribution of parasite burdens in their host populations is highly aggregated. This aggregation is fundamental to the ecology and epidemiology of helminth parasites. Results from a stochastic model predict that aggregation of helminth parasites is inversely related to the intensity of host immunity. Aggregation also decreases with antigenic heterogeneity and increases with heterogeneity in transmissibility among parasite strains. It is also found that the degree of aggregation is greater when immunity affects parasite fecundity than when immunity acts on host susceptibility. Potential relevance of this result for assessing the influence of vaccines that target either host susceptibility or parasite fecundity on the level of aggregation and consequent effects on drug resistance and disease prevalence are discussed.     

宁夏沙湖几种主要荒漠植物成丛性分析

该文对宁夏沙湖地区几种主要荒漠植物成丛或聚集分布的空间特征进行了研究,提出应用成丛性表征植物丛聚水平,并以丛生植物的丛径或散生植物的聚集分布尺度范围衡量植物成丛性的发育程度。其中散生植物的聚集尺度以Riplay's K点格局法进行计算。结果表明,植物的丛聚水平与生境条件密切相关,强日照、干热风、空旷的立地、较高土壤含水率、强透水蓄水能力等生境条件会促进植物成丛性的发育,而蒸腾胁迫低、土壤供水能力较差的生境条件下植物成丛性发育较弱。荒漠植物通过成丛或聚集分布可以形成局部微生境,减少地上部分的水分胁迫,是植物在群落水平适应环境的重要途径。     

Mechanistic studies on aggregation of polyethylenimine-DNA complexes and its prevention

Aggregation of polyethylenimine (PEI)-DNA complexes severely undermines their utility for gene delivery into mammalian cells. Herein we undertook to elucidate the mechanism of this deleterious phenomenon and to develop rational strategies for its prevention. The effect of temperature, surfactants, complex concentration, ionic strength, viscosity, and pH on the time course of this aggregation was systematically examined. The aggregation process was completely inhibited by 2.5% polyoxyethylene (100) stearate (POES) and to a lesser degree by other nonionic surfactants. Importantly, POES preserved the transfection efficiency of the complexes without inducing toxicity. The aggregation was also reduced by lowering the temperature and pH, diluting the complexes, and increasing the solution viscosity. It is concluded that PEI-DNA complexes aggregate primarily due to hydrophobic interactions, while electrostatic attractions play little role.     

Inducible expression of Tau repeat domain in cell models of tauopathy: aggregation is toxic to cells but can be reversed by inhibitor drugs

We generated several cell models of tauopathy in order to study the mechanisms of neurodegeneration in diseases involving abnormal changes of tau protein. N2a neuroblastoma cell lines were created that inducibly express different variants of the repeat domain of tau (tau(RD)) when exposed to doxycycline (Tet-On system). The following three constructs were chosen: (i) the repeat domain of tau that coincides with the core of Alzheimer paired helical filaments; (ii) the repeat domain with the deletion mutation DeltaK280 known from frontotemporal dementia and highly prone to spontaneous aggregation; and (iii) the repeat domain with DeltaK280 and two proline point mutations that inhibit aggregation. The comparison of wild-type, pro-aggregation, and anti-aggregation mutants shows the following. (a) Aggregation of tau(RD) is toxic to cells. (b) The degree of aggregation and toxicity depends on the propensity for beta-structure. (c) Soluble mutants of tau(RD) that cannot aggregate are not toxic. (d) Aggregation is preceded by fragmentation. (e) Fragmentation of tau(RD) in cells is initially due to a thrombin-like protease activity. (f) Phosphorylation of tau(RD) (at KXGS motifs) precedes aggregation but is not correlated with the degree of aggregation. (g) Aggregates of tau(RD) disappear when the expression is silenced, showing that aggregation is reversible. (h) Aggregation can be prevented by drugs and even pre-formed aggregates can be dissolved again by drugs. Thus, the cell models open up new insights into the relationship between the structure, expression, phosphorylation, aggregation, and toxicity of tau(RD) that can be used to test current hypotheses on tauopathy and to develop drugs that prevent the aggregation and degeneration of cells.     

Parameters of red blood cell aggregation as correlates of the inflammatory state

To identify clinically relevant parameters of red blood cell (RBC) aggregation, we examined correlations of aggregation parameters with C-reactive protein and fibrinogen in unstable angina (UA), acute myocardial infarction (AMI), and bacterial infection (BI). Aggregation parameters were derived from the distribution of RBC population into aggregate sizes (cells per aggregate) and changing of the distribution by flow-derived shear stress. Increased aggregation was observed in the following order: UA, AMI, and BI. The best correlation was obtained by integration of large aggregate fraction as a function of shear stress. To differentiate plasmatic from cellular factors in RBC aggregation, we determined the aggregation in the presence and absence of plasma and formulated a "plasma factor" (PF) ranging from 0 to 1. In AMI the enhanced aggregation was entirely due to PF (PF = 1), whereas in UA and BI it was due to both plasmatic and cellular factors (0 < or = PF < or = 1). It is proposed that clinically relevant parameters of RBC aggregation should express both RBC aggregate size distribution and aggregate resistance to disaggregation and distinguish between plasmatic and cellular factors.     

Thermodynamics of the hydrophobic effect. II. Calorimetric measurement of enthalpy, entropy, and heat capacity of aggregation of alkylamines and long aliphatic chains

The thermodynamics of long aliphatic chain alkylamine aggregation in aqueous solution was studied by isothermal titration calorimetry (ITC). Protonated alkylammonium cations with linear aliphatic chains of 10-14 carbon atoms were fully soluble in aqueous solution at the beginning of titration, but practically insoluble after deprotonation by titrating with sodium hydroxide. The alkylamines aggregated and precipitated during the reaction, enabling direct measurement of the enthalpy of aggregation. The enthalpy of aggregation became increasingly exothermic upon increasing the chain length. Hydrophobic aggregation was enthalpy-driven and entropy-opposed for alkylamines with 12-14 carbon atoms at room temperature. Direct observation of hydrophobic aggregation by ITC at constant temperature and pressure provided more accurate thermodynamic parameters than obtainable from van't Hoff analysis. Aggregation into liquid or solid phases could be distinguished by ITC, but not by van't Hoff analysis of alkylamine solubility data.     

基于16s rRNA序列的新蚤属二齿新蚤种团部分种类的分子系统发育关系

通过比较线粒体基因组16s rRNA基因片段的差异,研究了分布于我国的二齿新蚤种团(bidentatiformis group)7种新蚤的分子系统发育关系,以斯氏新蚤种团的特新蚤作为外群。结果显示,其中5个种 (Neopsylla bidentatiformis、N. mana、N. pleski、N. teratura和N. hongyangensis) 的种间序列差异小于1%,变异水平和种内变异相当,显示了它们之间较近的亲缘关系;N. abagaitui和上述5种之间有约4%的变异,说明该种有较长的分化历史。来自两个地区的二齿新蚤4个样本间有两种不同的基因型,而红羊新蚤可以归入其中的一种。加上形态特征的特点,可以认为红羊新蚤不应该属于毛新蚤种团,而属于二齿新蚤种团;至于其是否为二齿新蚤的同种异名,还有必要做进一步的研究。另外,N. siboi和形态近缘种N. teratura之间存在20%的变异,其原因有待进一步研究。