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1.
Karyotype analysis of Leishmania species and its use in classification and clinical diagnosis 总被引：15，自引：0，他引：15
S H Giannini M Schittini J S Keithly P W Warburton C R Cantor L H Van der Ploeg 《Science (New York, N.Y.)》1986,232(4751):762-765
Chromosomes of four species of Leishmania represented by ten different geographic isolates were analyzed by pulsed field gradient gel electrophoresis (PFG) to assess chromosome stability in these parasitic protozoans. Among different geographic isolates of the same subspecies, more than two-thirds of chromosomes had similar sizes, ethidium bromide staining intensities, and locations of alpha,beta-tubulin genes. However, among New World Leishmania, members of different species or subspecies have fewer than one-third of their chromosomes in common. Therefore, PFG karyotypes of Leishmania exhibit intraspecific variability similar to that reported for other parasitic protozoans. The greater similarities of the karyotypes of members of the same Leishmania subspecies may indicate that they represent valid taxa. These similarities also allowed the use of PFG in clinical diagnosis for rapid and accurate typing of patient isolates. 相似文献
2.
Anderson DM 《Science (New York, N.Y.)》1970,168(3927):132-133
The weevil Smicronyx quadrifer (broad sense) is restricted in host preference to the parasitic dodders (Cuscuta species) durin its adult life, but its larvae consistently move from dodder stems into living stems of certain hosts of dodders, where they feed, grow to maturity, and undergo metamorphosis. Such associations, involving three interacting organisms, are very unusual among phytogragous insects. 相似文献
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Young brood parasites that tolerate the company of host offspring challenge the existing evolutionary view of family life. In theory, all parasitic nestlings should be ruthlessly self-interested and should kill host offspring soon after hatching. Yet many species allow host young to live, even though they are rivals for host resources. Here we show that the tolerance of host nestlings by the parasitic brown-headed cowbird Molothrus ater is adaptive. Host young procure the cowbird a higher provisioning rate, so it grows more rapidly. The cowbird's unexpected altruism toward host offspring simply promotes its selfish interests in exploiting host parents. 相似文献
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Organisms allocate resources to male and female offspring in a process called sex allocation. In a Perspective, Stuart West and colleagues discuss what sex allocation tells us about evolution by natural selection and how sex allocation can be applied to understanding the mating structure of parasitic protozoans. 相似文献
6.
报道了红点唇瓢虫的重要内寄生天敌瓢虫隐尾跳小蜂的生活史、生活习性以及对寄主的影响和防治方法等。经在黑龙江省大庆地区调查表明，对其寄主红点唇瓢虫的寄生率可高达８２％，平均寄生率为５４％，是影响红点唇瓢虫种群数量的主导因子，因而导致红点唇瓢虫对杨圆蚧的控制力大幅度下降。 相似文献
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水平基因转移,一般分为细胞内部或者跨越物种边界的遗传物质交流。跨界直接介导方式,包括共生、内共生、寄生、嫁接等。细胞内的基因转移,主要包括细胞核与细胞器基因组间的相互渗透;跨越物种边界的遗传物质交流,主要涉及寄生与寄主植物的基因横向转移,寄主与寄生植物mRNA也会发生大规模的水平转移。基于基因组学研究进展,本研究综述了植物水平基因转移的迁移序列类型、迁移方向及迁移机制:首先,植物细胞的线粒体基因组能够整合细胞核转座元件以及叶绿体起源的tRNA基因,线粒体和叶绿体基因组的功能基因及间区序列能够迁移到核基因组;其次,植物种间,通过寄生、嫁接等方式转移大量的DNA(如线粒体基因、叶绿体基因和转座元件)和RNA(如mRNA)序列;迁移机制涉及到DNA介导和RNA介导方式,迁移方向包括单向和双向转移。迁移序列的基因功能活性研究是重要的后续研究方向。 相似文献
8.
Herre EA 《Science (New York, N.Y.)》1993,259(5100):1442-1445
It is often assumed that parasitic and disease-producing organisms tend to evolve benign relationships with their hosts over time. In contrast, theoretical arguments suggest that increased opportunities for parasite transmission will promote the evolution of increased virulence. The natural history of species-specific nematodes that parasitize fig-pollinating wasps permits the testing of these predictions in natural populations. For 11 species of Panamanian fig wasps, those species characterized by population structures that result in increased opportunities for parasite transmission harbor more virulent species of nematodes. In addition, differences in population structure are also associated with differences in other intra- and interspecific phenomena, including sex ratios among the fig wasp species, the degree of tension in the wasp-fig mutualism, and lethal combat among the males of parasitic wasps. 相似文献
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介绍了以淡水水产动物为中间寄主的华枝睾吸虫、卫氏并殖吸虫和广州管圆线虫引起的人体寄生虫病的危害、流行情况及防治. 相似文献
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通过对寄生植物肉苁蓉和寄主梭梭体内不同发育时期硝酸还原酶活性和硝态氮含量的测定,结果表明：寄生肉苁蓉的梭梭的硝酸还原酶活性和硝态氮含量均低于未寄生肉苁蓉的梭梭;与寄主梭梭不同的是,肉苁蓉体内的硝态氮含量高于梭梭同化枝内硝态氮含量,但其硝酸还原酶活性却较梭梭同化枝硝酸还原酶活性低,说明肉苁蓉体内氮素代谢除了以硝酸还原酶为主外,可能还有其他氮代谢途径的参与．肉苁蓉寄生后,将梭梭体内的氮素大量吸收,致使梭梭生长严重受抑制,表现为梭梭同化枝叶绿素含量下降,同化枝生长量严重减少．因此,从寄生关系判断,肉苁蓉对梭梭的寄生为有害寄生． 相似文献
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寄生植物与其寄主植物间存在着广泛的化学信号交流,从而保证了寄生关系的建立.近年来,这一信号交流已经引起了学者的广泛关注.本文从根系化学信号与寄生植物的关系、诱导寄生植物种子萌发及吸器形成的化学物质、寄主植物萌发刺激物的生物合成途径和寄生植物对寄主植物释放刺激物的识别等几方面进行综述. 相似文献
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通过对我国13个省(区、市)自然条件下昆虫染螨情况的野外调查,结果表明,染螨昆虫有13目、50科。并报道了部分昆虫染螨率、染螨部位及其主要螨类类群(蜱螨亚纲3目、16科),还讨论了寄生螨对寄主及其体位的选择偏好性等现象。 相似文献
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珠江水系西江的局部支流近年出现了严重危害网箱养殖和江河鱼类资源的寄生虫病害,初步鉴定该虫隶属于甲壳纲、等足目、鳃虫科、细角鳃虫属(RocinelaLeach),是国内新发现的淡水鱼类寄生虫。文章就该虫对麦鲮的寄生行为进行了研究,结果表明:该虫具很强的寄生能力,240 min内累积感染率达90%。对寄生部位具一定的选择性,以寄生在鳃腔比例最大(55.5%),胸鳍基部(25.9%)次之。对麦鲮具较强的致死效应,23 h的累积死亡率为16.7%。吸血后体长(L)显著增长,而体宽(W)基本无变化。从寄主身上主动脱落的虫体,其L和L/W的增值比(%)均显著高于因使寄主致死而被动脱落的虫体(P<0.05);而仍在寄主身上的虫体,其L和L/W的增值比(%)则因各自摄食量的不同而存在较大差异。 相似文献
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Werren JH 《Science (New York, N.Y.)》1980,208(4448):1157-1159
Females of the parasitic wasp Nasonia vitripennis adjust the sex ratio of their broods according to whether they are a first or second wasp to parasitize a host. The first wasp produces a strong daughter bias. The second wasp adjusts the prorportion of sons to the relative level of local mate competition, as predicted by a natural selection model. The results provide a quantitative test of sex ratio theory. 相似文献
16.
菊科植物(Compsitae)在新疆具有重要经济价值,主要的有油料作物,常用的中草药,重要的早春牧草,固沙植物,蜜源植物和观赏植物等,柄锈菌属(Puccinia)是菊科植物重要的病原真菌。作者1987～1988年采集并收集整理八一农学院真菌标本室保存的自60年代起至今在全疆各地采集的菊科植物锈病标本共103份,经光学显微镜和扫描电子显微镜下观察各份标本的的夏孢子,冬孢子形态,参考性孢子器及锈孢子器形态和寄主,分类鉴定出新疆菊科植物柄锈菌28个种,18个已知种,10个是全国新记录:Puccinia saussureae;P.artemisicola;P.cousiniae;P.sonchina;P.chondrillina;P.crepidis-sibiricae;P.artemisiae-norvegicae;P.peisisca;P.xanthii;P.cichorii。寄主植物隶属于菊科21个属,34个种,所有引证标本保存在新疆八一农学院真菌标本室(HMAAC)。 相似文献
17.
Ehleringer JR Schulze ED Ziegler H Lange OL Farquhar GD Cowar IR 《Science (New York, N.Y.)》1985,227(4693):1479-1481
Most mistletoes parasitize higher plants by tapping the xylem (a conduction tissue) of their hosts. Field observations of diurnal gas exchange parameters and carbon isotope ratios in xylem-tapping mistletoes from three continents support the hypotheses that water use efficiency and carbon isotope composition are related and that mistletoes which are parasitic for water are also nutrient parasites, differing in their water use efficiency relative to that of their hosts on the basis of host nitrogen supply in the transpiration stream. 相似文献
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Philippot P Van Zuilen M Lepot K Thomazo C Farquhar J Van Kranendonk MJ 《Science (New York, N.Y.)》2007,317(5844):1534-1537
Microscopic sulfides with low 34S/32S ratios in marine sulfate deposits from the 3490-million-year old Dresser Formation, Australia, have been interpreted as evidence for the presence of early sulfate-reducing organisms on Earth. We show that these microscopic sulfides have a mass-independently fractionated sulfur isotopic anomaly (Delta33S) that differs from that of their host sulfate (barite). These microscopic sulfides could not have been produced by sulfate-reducing microbes, nor by abiologic processes that involve reduction of sulfate. Instead, we interpret the combined negative delta34S and positive Delta33S signature of these microscopic sulfides as evidence for the early existence of organisms that disproportionate elemental sulfur. 相似文献
19.
L A Curtis 《Science (New York, N.Y.)》1987,235(4795):1509-1511
Estuarine snails Ilyanassa obsoleta bearing larvae of the trematode Gynaecotyla adunca behave singularly in comparison with conspecifics lacking this parasite. Following high tides, and especially at night, infected snails were found stranded high on beaches and sandbars. Semiterrestrial crustaceans living well up on the shore serve as the next host, and the modified (induced) snail behavior is apparently a parasite adaptation facilitating cercarial transmission to these crustaceans. The altered behavior is unusual because of its apparent enhancement of host-to-host transmission by cercariae rather than predation, the process commonly recognized as being enhanced by parasitic modification of host behavior. 相似文献
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寄生蜂感受器的形态与功能 总被引：3，自引：0，他引：3
分析了寄生蜂的触角、足、产卵器上感受器的形态、分布和功能，比较了两性间的差异，概述了近年来国内外在寄生蜂感受器超微结构方面的研究进展，描述了它们在寻找寄主、将卵产入寄主体内过程中的作用。 相似文献