鹅掌楸属植物的多糖壁前体和花粉管的生长

本文观察描述了中国鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎｃｈｉｎｅｎｓｅ）和北美鹅掌楸（Ｌ．ｔｕｌｉｐｉｆｅｒａ）花粉在异已柱头萌发和花粉管生长期间多糖壁前体的发生、形态结构和生理功能．１、多糖壁前体在形态上有Ｐ－粒子（Ｐｏｌｙｓａｃｃｈａｒｉｄｅｐａｒｔｉｃｌｅｓ）,被膜小泡（ｃｏａｔｅｄｖｅｓｉｃｌｅ）和小泡（ｖｅｓｉｃｌｅ）三种。２、Ｐ－粒子于单核花粉期已经发生,至花粉管延伸期为发生高峰。多糖壁前体是在高尔基体,内质网和线粒体的相继、连续作用下,由淀粉质体、蛋白体和脂滴降解形成．３、Ｐ－粒子的形态随不同发育时期而变化,早期为成群的电子透明小泡,或为蛋白质束缚的挤压成多面体形,后期为内含颗粒或微纤丝的无被膜粒子或具刺被膜粒子。４、Ｐ－粒子移至管端．或融合或单个通过周质内质网（ＣＥＲ）,释放内容物参与管端壁的形成,被膜小池和小泡移至花粉管次顶端区向质膜外分泌,参与花粉管壁内层的形成,或移至管端,提供膜片。最后讨论了亲和性与超微结构特征的关系．     

棘腹硅体内寄生原生动物两新种记述：动鞭毛纲：动基体目：锥体 科;粘孢子…

本文记述棘腹蛙Ｒａｎａ ｂｏｕｌｅｎｇｅｒｉ Ｇｕｎｔｈｅｒ体内寄生的两种文献中未报道过的原生动物,一种是利川锥虫新种,Ｔｒｙｐａｎｏｓｏｍａ ｌｉｃｈｕａｎｅｎｓｉｓ ｓｐ．ｎｏｖ．,其主要特征是,鞭毛较粗,一般有伸出体外,故不形成游离的鞭毛;另一种是蛙两极虫新种,Ｍｙｘｉｄｉｕｍ ｂｏｕｌｅｎｇｅｒｉ ｓｐ．ｎｏｖ．,孢子卵形,两端钝圆,壳厚,壳面光滑,缝线直而宽。     

棕鞭藻对蛋白核小球藻的摄食及其营养策略

在研究稻草秸秆对蛋白核小球藻(Chlorella pyrenoidosa)的化感作用时,偶然发现一株对蛋白核小球藻具有强烈的取食作用的鞭毛虫,能有效抑制小球藻的大量繁殖。经形态学观察,该种鞭毛虫具有2片淡黄色色素体,片状、周生;虫体呈球形、椭圆形或卵形,能变形,具2根不等长的鞭毛,从细胞顶部伸出;长鞭毛约为虫体的1.5倍,短鞭毛约为虫体的0.5倍;对蛋白核小球藻的吞噬能力极强,每个虫体可以吞噬3~4个小球藻,虫体大小因吞噬物的多少变化较大。初步确定这种鞭毛虫为棕鞭藻(Ochromonas sp.)。在SE、稻草以及麦粒3种培养基中的种群生长表明,这种棕鞭藻在麦粒培养基最易培养,生长速度最快。结果表明,这种棕鞭藻为混合营养类型,但以吞噬营养为主。     

杜氏利什曼原虫无鞭毛体形态及分裂过程的电镜观察

无鞭毛体呈椭圆形,后部有深杯样表膜凹陷,虫体一侧有一小突起。膜下微管数为74—90个。细胞核有1—3个核仁,细胞质内充满核糖体,动基体大小不一,多呈腊肠形,由动基体延伸形成长袋状线粒体。靠近鞭毛袋一侧有一组4个游离微管,鞭毛轴丝为9+2结构,并具有基板_1和基板_2结构,基体为9组三联微管。 无鞭毛体分裂从新鞭毛轴丝形成和动基体DNA纤丝伸长开始,以后DNA纤丝带出现裂隙,继之核仁裂碎、消失,形成核内纺锤体,开始细胞核的分裂,随后虫体一侧表膜出现凹陷,新膜下微管和表膜先后形成,并从此处向细胞内伸入,最后完全包绕两个分裂的虫体,完成细胞分裂。随着虫体的发育繁殖,含虫空泡涨大,电子致密度变低。分裂后的无鞭毛体贴附到含虫空泡膜,并向巨噬细胞细胞质内移动,最后离开原来的含虫空泡,形成新的含虫空泡。     

黑龙江省东部鸡西盆地城子河组下部早白垩世欧特里夫晚期海相沟鞭 …

描述黑龙江省东部西盆地典型的城子河组下部海相层（包括南部带海相层,即原“石河北组”）的沟鞭藻类化石１５属１９种,含１新种和１新组合种。它们可分出两个沟鞭藻组合：Ｏｄｏｎｔｏｃｈｉｔｉｎａ ｏｐｅｒｃｕｌａｔａ－Ｍｕｄｅｒｏｎ－ｇｉａ ｔｅｌｔｒａｃａｎｔｈａ组合（下部）和Ｖｅｓｐｅｏｐｓｉｓ ｚｈａｏｄｏｎｇｅｎｓｉｓ组合（上部）;讨论沟鞭藻组合的特征及其地质时代,并与国际上有关地层进行对比,认为     

人埃里希体的研究进展

人埃里希体包括３个种：Ｅｈｒｌｉｃｈｉａ ｓｅｎｎｅｔｓｕ、Ｅｈｒｌｉｃｈｉａ ｃｈａｆｆｅｅｎｉｓｉｓ和人粒细胞埃里希体（ＨＧＥ）。Ｅ．ｓｅｎｎｅｔｓｕ和Ｅ．ｃｈａｆｆｅｅｎｓｉｓ主要寄生在单核细胞和巨噬细胞内,而ＨＧＥ主要寄生在粒细胞内。ＨＧＥ和Ｅ．ｃｈａｆｆｅｅｎｓｉｓ的传播媒介是蜱。３种人埃里希体分属埃里希体属３个不同的１６Ｓ ｒＲＮＡ基因群。     

粗糙沼虾精子的超微结构研究

利用电镜及细胞化学方法,研究了粗糙沼虾（Ｍａｃｒｏｂｒａｃｈｉｕｍ ａｓｐｅｒｕｌｕｍ）精子的形态和超微结构。结果表明：精子无鞭毛、不运动,由后主体部、中间帽状体和前端棘突组成。主体部呈浅状,内有非浓缩的核,核内含有许多泡囊造近帽状体的核部,分布着许多膜本,膜层体与帽状体紧密相连。棘突具有间隔约３１ｎｍ的珏纹。环纹由直径为４～６ｎｍ的丝状体组成并与环纹相垂直。精子无明显的顶体区。     

大黄蝠锥虫生活史的研究

大黄蝠锥虫进入实验媒介体——热带臭虫胃内后2小时变为上鞭毛体,第3天起在后肠形成后循环型锥虫。传播方式为污染。在大黄蝠体内潜伏期为1—2天,第6—7天虫体充分长大。未见分裂及细胞内的锥虫。本虫可感染小黄蝠;但末感染埤、螨和白纹伊蚊、致乏库蚊。虫体在NNN培养基中的发育和在热带臭虫中的发育相似。实验结果有力地提示本虫的天然媒介是臭虫,并很可能是Cimex flavifuscus。     

卡氏膜球藻鞭毛伸缩节律的研究

卡氏膜球藻（Ｈｙｍｅｎｏｍｏｎａｓｃａｒｔｅｒａｅ）是一种单细胞海藻,细胞圆球形,表面覆盖一层球形石（Ｃｏｃｃｏｌｉｔｈｓ）。两条鞭毛稍不等长,着生于细胞前端,鞭毛长约为细胞直径的１．５倍。在２５±℃,光照强度２０００ｌｘ,光暗时间比１４：１０小时条件下,用ＭＥＳⅢ培养基培养卡氏膜球藻,发现细胞在光照条件下伸出鞭毛,活跃游动;在黑暗条件下缩回鞭毛,沉于培养瓶底。进一步试验证明：１．光刺激细胞伸出鞭毛,黑暗刺激细胞缩回鞭毛。２．鞭毛的伸缩与培养中的光暗周期变化严格对应,即光周期开始后２０分钟,细胞开始伸出鞭毛;暗周期一开始,鞭毛就向细胞内收缩。３．在连续光照条件下,鞭毛的周期性伸缩现象消失。所以,卡氏膜球藻鞭毛周期性伸缩是一种受光暗周期调节的外源节律。这种鞭毛伸缩的节律现象在藻类是第一次报道。     

中国鲎精子发生的研究: Ⅰ.精子的发生过程

利用光镜和电镜技术,结合细胞化学方法研究了中国鲎（Ｔａｃｈｙｐｌｅｕｓ ｔｒｉｄｅｎｔａｔｕｓ）精子发生过程．结果表明：中国鲎精子发生可划分为精原细胞、初级精母细胞、次级精母细胞、精子细胞及精子五个时期。在精子发生中,出现顶体丝结构,这是鲎精子发生的一个重要特征。页体由顶囊和亚顶体间隙组成。顶体丝由顶体囊底部发出,穿过亚顶体间隙,贯穿核中央部分的通道．沿核底部穿出,绕核缠绕,形成约２８匝的百体丝螺圈。这一特点可能与精子在受精时必须穿越厚的卵膜密切相关。成熟精子头部如梨形,前端覆盖有吸盘状后帽,头部长约４μｍ,尾部鞭毛长达３５μｍ、鞭毛为９ ×２结构,在鞭毛基部有一对中心粒。     

Attachment of Trypanosoma cruzi Epimastigotes to Hydrophobic Substrates and Use of this Property to Separate Stages and Promote Metacyclogenesis

In vivo, epimastigotes of Trypanosoma cruzi colonize a lipidic superficial layer of the rectal cuticle of the vector Triatoma infestans. In vitro, epimastigotes of four cultured strains and one strain from reduviids use a terminal area of the flagellum to attach to a variety of artificial hydrophobic substances, such as hydrocarbons and a range of synthetic plastics. Trypomastigotes did not attach to these substrates. Hydrophilic molecules, such as neutral or negatively charged polysaccharides. did not facilitate binding. Epimastigotes and trypomastigotes were artificially bound by electrostatic forces to positively charged chitosan or DEAE-Sephacel over their entire surface. Tween 20 and lipid-binding serum albumin effectively inhibited the hydrophobic attachment. Based on this hydrophobic interaction of epimastigotes. a new chromatography technique has been devised to gently separate trypomastigotes from epimastigotes using octacosane-coated beads. Furthermore, the in vitro transformation of epimastigotes to trypomastigotes was enhanced if epimastigotes were permitted to attach to hydrophobic, wax-coated culture vessels.     

Characterization of two sets of subpolar flagella in Bradyrhizobium japonicum

Bradyrhizobium japonicum is one of the soil bacteria that form nodules on soybean roots. The cell has two sets of flagellar systems, one thick flagellum and a few thin flagella, uniquely growing at subpolar positions. The thick flagellum appears to be semicoiled in morphology, and the thin flagella were in a tight-curly form as observed by dark-field microscopy. Flagellin genes were identified from the amino acid sequence of each flagellin. Flagellar genes for the thick flagellum are scattered into several clusters on the genome, while those genes for the thin flagellum are compactly organized in one cluster. Both types of flagella are powered by proton-driven motors. The swimming propulsion is supplied mainly by the thick flagellum. B. japonicum flagellar systems resemble the polar-lateral flagellar systems of Vibrio species but differ in several aspects.     

The cytostome of Trypanosoma cruzi epimastigotes is associated with the flagellar complex.

Okuda, K., Esteva, M., Segura, E. L., and Bijovsky, A. T. 1999. The cytostome of Trypanosoma cruzi epimastigotes is associated with the flagellar complex. Experimental Parasitology 92, 223-231. Proliferative forms of Trypanosoma cruzi, amastigotes and epimastigotes, have a cytostome, a specialized structure formed by an invagination of the flagellar pocket's membrane surrounded by microtubules and frequently followed by a row of vesicles. All this assemblage penetrates deeply into the cytoplasm overpassing the nucleus. This structure, together with the flagellar pocket, appears to play an important role in the nutrition of the parasite. We demonstrated that the monoclonal antibody 2C4, made-up against isolated flagellar complex of T. cruzi epimastigotes, recognizes a protein doublet of 76 and 87 kDa in total epimastigotes homogenate. The 76-kDa polypeptide is enriched in the detergent-soluble fraction whereas the 87-kDa polypeptide is highly represented in the insoluble fractions and the purified flagella. Immuno-fluorescence assays show the antigen as a small spot at the flagellar pocket region. Immunogold labeling of ultrathin sections of epimastigote forms reveals gold particles at the opening of flagellar pocket, concentrated in the cytostome region. Immunocytochemistry of epimastigote whole-mount cytoskeletons reveals the labeling on an array of three to four microtubules that appears attached to flagellum, running in the direction of the nucleus. Ultrastructural observations have shown that the posterior region of isolated flagella, corresponding to the level of the flagellar pocket, possesses a microtubular structure compatible with that from the cytostome. The relationship between the cytostome, an endocytic organelle, and the flagellum is here described for the first time.     

Trypanosoma cruzi: distribution of fluorescently labeled tubulin and actin in epimastigotes

Cytoskeletal components were visualized in epimastigote forms of Trypanosoma cruzi by double immunofluorescence microscopy using monospecific antibodies against tubulin and against actin. Intense staining of the flagellum and the edges of the cell body was observed when the cells were stained with anti-tubulin, reflecting the presence of the basal bodies, the flagellar axoneme and the subpellicular microtubules. A less intense staining was seen in the cell body of epimastigotes stained with anti-actin. However, an intense staining was observed with this antibody in the flagellum, in a pattern similar to that observed with anti-tubulin. It is suggested that the paraxial structure, which is formed by a complex array of 6-nm-thick microfilaments is composed, at least in part, of actin.     

Fine structure of Blastocrithidia culicis as seen in thin sections and freeze-fracture replicas

The fine structure of epimastigotes of Blastocrithidia culicis was studied by transmission electron microscopy of thin sections and freeze-fracture replicas. This parasite presents a well developed endoplasmic reticulum and Golgi complex systems. Differences in the density and organization of the intramembranous particles were observed between the membranes which enclose the cell body and the flagellum. Ridge-like elevations, visualized in freeze-fracture replicas, were observed in sites where the mitochondrial branches touched the plasma membrane. A special array of membrane particles was observed on both faces of the flagellar and the cell body membranes at the region where the flagellum adheres to the cell body. It appeared as strands made of two rows of membrane particles. Filipin-treated cells were used for the localization of membrane sterols in freeze-fracture replicas. The number of filipin-sterol complexes varied from cell to cell. In some cells, rows of filipin-sterol complexes were seen. No complexes were observed in the region of the attachment of the flagellum to the cell body.     

Antigenic differentiation of the kinetoplastids Leishmania braziliensis and Trypanosoma cruzi by means of monoclonal antibodies

BALB/c mice were hyperimmunized with non-infectious extracts of either Leishmania braziliensis promastigotes or Trypanosoma cruzi epimastigotes. When spleen cells from these mice were fused with P3X63Ag8 plasmacytoma cells, the resultant hybridomas synthesized monoclonal antibodies which displayed specific reactivity by indirect immunofluorescence with distinct subcellular components of the parasites. These studies revealed that antigens associated with the flagellum and with a nongranular component of the cytoplasm would account for much of the serologic cross-reactivity observed between the two species. Conversely, antigens associated with surface and/or cytoplasmic granules and with an intracellular organelle believed to be the kinetoplast appeared to be species-specific.     

Deletion of an immunodominant Trypanosoma cruzi surface glycoprotein disrupts flagellum-cell adhesion

Null mutants of the Trypanosoma cruzi insect stage-specific glycoprotein GP72 were created by targeted gene replacement. Targeting plasmids were constructed in which the neomycin phosphotransferase and hygromycin phosphotransferase genes were flanked by GP72 sequences. These plasmids were sequentially transfected into T. cruzi epimastigotes by electroporation. Southern blot analyzes indicated that precise replacement of the two genes had occurred. No aberrant rearrangements occurred at the GP72 locus and no GP72 gene sequences had been translocated elsewhere in the genome. Western blots confirmed that GP72 is not expressed in these null mutants. The morphology of the mutants is dramatically different from wild-type. In both mutant and wild-type parasites, the flagellum emerges from the flagellar pocket. In the null mutant the normal attachment of the flagellum to the cell membrane of the parasite is lost.     

Trypanosoma cruzi glycoprotein of Mr 56000: characterization and assessment of its potential to protect against fatal parasite infections

A ∼ 56 000 Da membrane glycoprotein purified from epimastigotes of Trypanosoma cruzi was characterized biochemically and tested for its efficacy to induce protection in mice from a lethal challenge with this protozoan parasite. Immunofluorescence assays with live and formalin-fixed epimastigotes and trypomastigotes localized the glycoprotein to the flagellum, the body of the parasite, and the cell membrane. Immunoblotting demonstrated the glyco-protein's presence in nearly equal amounts in all developmental stages of several T. cruzi isolates. Mice immunized with the purified glycoprotein and challenged with 10000 infectious trypomastigote forms of isolate Y survived the controls by up to four days. This significant protection makes this antigen a potential candidate for a multi-subunit vaccine against 7. cruzi.     

Antigenic Differentiation of the Kinetoplastids Leishmania braziliensis and Trypanosoma cruzi by Means of Monoclonal Antibodies1

BALB/c mice were hyperimmunized with non-infectious extracts of either Leishmania braziliensis promastigotes or Trypanosoma cruzi epimastigotes. When spleen cells from these mice were fused with P3X63Ag8 plasmacytoma cells, the resultant hybridomas synthesized monoclonal antibodies which displayed specific reactivity by indirect immunofluorescence with distinct subcellular components of the parasites. These studies revealed that antigens associated with the flagellum and with a nongranular component of the cytoplasm would account for much of the serologic cross-reactivity observed between the two species. Conversely, antigens associated with surface and/or cytoplasmic granules and with an intracellular organelle believed to be the kinetoplast appeared to be species-specific.     

Trypanosoma cruzi: antigenic composition of axonemes and flagellar membranes of epimastigotes cultured in vitro

Trypanosoma cruzi epimastigotes were sonicated in a medium containing sucrose, albumin, and calcium as stabilizers, to yield mainly unbroken parasites and free flagella. The latter were separated, first by differential centrifugation and finally by an isopicnic centrifugation, in a discontinuous sucrose gradient. The flagella obtained in the $\text{1.66}\text{1.84}\text{M}$ interphase show, by electron microscopy, the typical axonemal structure surrounded by the flagellar membrane and are completely free of extraneous subcellular components. They are also very homogeneous by polyacrylamide gel electrophoresis and enzyme marker criteria. The purified flagella were further subfractionated into well-preserved axonemes and a soluble flagellar membrane preparation. In order to detect in these fractions only the parasite immunogens that elicit a humoral response in humans, sera of chagasic patients were exclusively used. Indirect immunofluorescence reveals that both intact and membrane-free flagella are reactive. Passive hemagglutination and complement fixation of the flagellar membrane and axonemal fractions show a 21- and 8-fold purification, respectively, over a standard (Maekelt) antigen used for diagnostic purposes. Approximately 10% of the antigenicity of the total parasite is found in the flagellum, and two-thirds of this in the membrane. Double-immunodiffusion tests reveal the presence of two antigens in the axonemes and four in the flagellar membranes, one of which is common with one of the three antigens detected in a total parasite membrane fraction. The high degree of flagellar purification achieved here and the use of chagasic sera allow to conclude that at least six antigenic determinants for humoral response in humans are present in the flagellum of T. cruzi epimastigotes, two of them localized in the axoneme and four in the flagellar membrane.