Biochemical Aspects of Schistosome Behaviour

The haematophagous blood tiematodes that comprise the genus Schistosoma live in a stable environment with an adequate food supply and an efficient waste disposal system.

The main food is glucose obtained from the host blood and assimilated through the tegument Other dietary factors are assimilated through the tegument or the gut epithelium. The male fluke supplements and augments the diet of the female who is thus able to concentrate on egg production.

Live flukes resist attack by the host by secreting an immunologically inert envelope and by incorporating unchanged host serum protein into their structures. They can also incorporate host structural fatty acids unchanged.     

A preliminary study to understand the effect of Fasciola hepatica tegument on naïve macrophages and humoral responses in an ovine model

Fasciola hepatica, the liver fluke, is a highly evolved endo-parasite that uses various mechanisms to evade the host immune system. The immunosuppressive capabilities of the parasite's excretory/secretory products have been well demonstrated by previous independent studies. However, the role of the parasite's tegument in the immune responses remains to be investigated. In this study, the effect of the tegument and other fractions of adult F. hepatica (excretory/secretory, liver fluke homogenate and liver fluke homogenate without tegument) in the activation of naïve macrophages in vitro was investigated using an ovine model. In addition, an immunoproteomic approach was used to investigate the characteristics of humoral antibody responses developed in sheep against the tegument fraction. The results indicated significantly increased arginase expression in macrophages incubated with the tegument and excretory/secretory fractions. Two dimensional gel electrophoresis of the tegument demonstrated approximately 100 protein spots, with only four of these spots were highly reactive with the positive serum as determined by 2-DE immunoblotting. These results give a preliminary indication that the liver fluke tegument may play role in avoiding hosts’ protective immune responses against itself.     

Morphological changes to early stage Taenia solium cysticerci following oxfendazole treatment

The progressive morphological changes to early stage Taenia solium cysticerci following the treatment of pigs with a single therapeutic dose of oxfendazole (30 mg/kg), are described. On Day 1 after treatment, no obvious changes occurred in the general appearance of the larvae but alternations were seen by electron microscope, with an apparent reduction in the number of microtriches, and a complete disappearance of the tegument. Numerous granules were seen to have accumulated in the tegument cells. As treatment progressed, damage to the cysticerci was more serious and, by five days, all cysticerci were seen to be in an advanced stage of degeneration. By 45 days post-treatment, all cysts were calcified. These results suggest that oxfendazole is a highly effective drug against T. solium cysticerci in the early stages of development.     

Host cellular components adhering to the tegument of schistosomes from cattle, buffalo, hippopotamus and lechwe

The teguments of adult Schistosoma mattheei from cattle and buffalo, S. hippopotami from hippopotamus and S. margrebowiei from lechwe were examined by means of scanning electron microscopy for cells possibly engaged in immunological action. Leukocytes were observed on the teguments of the schistosomes from all 4 host species. Although certain of these cells seemed to be fused to the surface membrane of the worms, they did not display pseudopodia. The tegument of certain schistosomes from buffalo exhibited cells the size of platelets with dendritic structures connected to the tegument of the parasite. The results seem to indicate that, as with laboratory hosts, naturally infected domestic and wild hosts are unable to mount an effective cellular response against the tegument of live adult shistosomes. The possible role of platelets in immunology against schistosomes is mentioned.     

Identification and localization of the structural proteins of anguillid herpesvirus 1

ABSTRACT: Many of the known fish herpesviruses have important aquaculture species as their natural host, and may cause serious disease and mortality. Anguillid herpesvirus 1 (AngHV-1) causes a hemorrhagic disease in European eel, Anguilla anguilla. Despite their importance, fundamental molecular knowledge on fish herpesviruses is still limited. In this study we describe the identification and localization of the structural proteins of AngHV-1. Purified virions were fractionated into a capsid-tegument and an envelope fraction, and premature capsids were isolated from infected cells. Proteins were extracted by different methods and identified by mass spectrometry. A total of 40 structural proteins were identified, of which 7 could be assigned to the capsid, 11 to the envelope, and 22 to the tegument. The identification and localization of these proteins allowed functional predictions. Our findings include the identification of the putative capsid triplex protein 1, the predominant tegument protein, and the major antigenic envelope proteins. Eighteen of the 40 AngHV-1 structural proteins had sequence homologues in related Cyprinid herpesvirus 3 (CyHV-3). Conservation of fish herpesvirus structural genes seemed to be high for the capsid proteins, limited for the tegument proteins, and low for the envelope proteins. The identification and localization of the structural proteins of AngHV-1 in this study adds to the fundamental knowledge of members of the Alloherpesviridae family, especially of the Cyprinivirus genus.     

Time-dependent changes to the tegumental system and gastrodermis of adult Fasciola hepatica following treatment in vivo with triclabendazole in the sheep host

Eight indoor-reared cross-bred sheep with no pre-exposure to Fasciola hepatica were infected by oral gavage with 200 metacercarial cysts of the triclabendazole (TCBZ)-susceptible Cullompton isolate of F. hepatica. At 12 weeks post-infection, sheep were dosed with 10mg/kg triclabendazole. Two sheep per time period were euthanized at 48 h, 72 h and 96 h post-treatment (pt). Two control sheep were euthanized alongside the 96 h triclabendazole-treated sheep. Flukes were recovered from each of the sheeps liver and, if present, from the gall bladder and they were processed for transmission electron microscopy (TEM). Disruption to the ultrastructure of the tegument became increasingly severe over time pt. Flukes recovered at 48 h pt showed widespread blebbing of the apical plasma membrane and swelling of the mucopolysaccharide masses surrounding the basal infolds. There was evidence of reduced secretory activity in the tegumental cells and spacing between the cells. Sloughing of the tegumental syncytium was observed at 72 h pt. The subtegumental musculature, parenchyma and tegumental cells were severely disrupted. At 96 h pt, all of the flukes were totally devoid of tegument. Disruption to the subtegumental tissue and somatic musculature was severe, and was so extreme in some specimens that the tegumental cells were barely discernible. Disruption to the gastrodermis was also progressive, though not as severe as disruption to the tegument. There was a general decline of secretory activity with time pt. Autophagic activity was apparent from 48 h pt and became more widespread with increasing time, culminating in breakdown of the gastrodermal cell cytoplasm. The mitochondria were swollen and electron-lucent and the cisternae of the granular endoplasmic reticulum were dilated and fragmented from 72 h pt.     

日本血吸虫蛋白质组学研究

蛋白质组学是研究一种细胞、组织或完整生物体在特定时空上全部蛋白质及其存在方式的学科。近年来,应用蛋白质组学技术开展了日本血吸虫尾蚴、童虫、成虫蛋白质组,成虫性别差异和排泄分泌物蛋白质组,体被蛋白质组,与药物和诊断相关的蛋白质组等多方面的研究,增加了人们对日本血吸虫的生长发育、免疫逃避等机制的了解,为发掘血吸虫病疫苗、诊断和药物靶点提供了新的线索。     

An in vitro effect of propolis on adult worms of Fasciola gigantica

The effect of Siwa propolis on adult flukes was evaluated using scanning electron microcopy. It gave an overview of the surface architecture of the tegument of Fasciola gigantica apical cone. The base of the spines appeared to be "flaking off" and showed severe blebbing after 24h incubation with 10 micro/ml propolis. This swelling became so sever and the spines were barely visible, on increasing the concentration to 20 micro/ml. Besides, there were many large blebs on the apical cone, a number of which appeared to have burst, causing lesions and the tegument was marked by a number of pits caused by the loss of spines. With the higher concentration of 30 micro/ml, erosion of the surface had occurred to such extent that no tegument remained, only a mass of fibrous structures. The tegumental changes occurred following incubation in propolis were compared with those observed with triclabendazole (TCBZ) "Fasinex" because of its high efficacy against both mature and immature flukes.     

Tegumental surface changes in juvenile Fasciola hepatica in response to treatment in vivo with triclabendazole

Eight indoor-reared crossbred sheep with no pre-exposure to Fasciola hepatica were infected, by oral gavage, with 200 metacercarial cysts of the triclabendazole (TCBZ)-susceptible Cullompton isolate of F. hepatica. Anthelmintic dosing occurred at 4 weeks post-infection with 10 mg/kg triclabendazole. Two treated sheep were euthanized at 48 h, 72 h and 96 h post-treatment with triclabendazole. Two control sheep were euthanized alongside the 48 h triclabendazole-treated sheep. Juvenile flukes were recovered from each of the sheeps' liver and processed for scanning electron microscopy (SEM). Flukes were still active 48 h post-treatment and displayed limited morphological disruption. There was some blebbing and sloughing of the tegument around the oral sucker. In several of the specimens, an extra layer had been deposited on the fluke surface, giving it a flattened appearance. At 72 h post-treatment, only one fluke remained alive and the disruption varied in degree. In the majority of flukes, there was severe swelling of the tegument, accompanied by isolated areas of flattening along the lateral margins of the flukes and in the tail region. Limited areas of sloughing occurred in the tail region. In more seriously affected specimens, the syncytium had been stripped away to reveal the basal lamina and some deeper lesions were also observed. By 96 h post-treatment, all the flukes were dead and were grossly disrupted. They were totally devoid of tegument and deep lesions exposed the internal tissues of the fluke.     

Effect of Calea serrata Less. n-hexane extract on acetylcholinesterase of larvae ticks and brain Wistar rats

The stem bark of Acacia oxyphylla Graham ex Bentham is used as an anthelmintic by the natives of Mizoram (North-East India). Therefore, the aim of the study was to assess the effect of the active compound isolated from A. oxyphylla on the tegument of adult Raillietina echinobothrida and Ascaridia galli. The test parasites R. echinobothrida and A. galli were incubated in physiological buffered saline containing 0.0005, 0.001, 0.05, 0.1 and 1mg/ml of the isolated compound. The alterations in the tegument of the parasites post paralysis were examined using electron microscopes. The compound reduced the cestode's motility soon after incubation, but did not induce paralysis in the nematodes till about 11-14 h at highest concentration. The compound caused extensive digestion of cestode tegument as evident by electron microscopy. Disorganization of muscle bundles, loss of cell-cell contact, extreme vacuolization and oedema were some of the changes observed. Loss of cellular organelles combined with distortion of those present was markedly noted throughout the parasite tissue. Deformation and disorganization of epicuticle, disruption of mitochondrial and nuclear membrane were also observed in nematode exposed to the active compound of the plant. Substantial structural deformities in the treated parasites are indicative of an efficient vermicidal activity of the isolated compound against cestodes and nematodes.     

豌豆状囊尾蚴组织化学的观察

观察了豌豆状囊尾蚴的主要生化指标的定位分布和相对含量。结果表明：头钩内含丰富的网状纤维。糖原主要分布于实质组织，尤以吸盘部位为最丰富。ＡＫＰ、ＡＣＰ和ＡＴＰ酶定位于皮层和钙质小体。本作者认为，这３种酶分布于皮层可能是协助皮层从宿主组织摄取葡萄糖。     

用抗虫体表膜抗原抗体测定犬细粒棘球绦虫粪抗原

利用Echinococcus granulosus(Eg)成虫表膜抗原抗体夹心ELISA方法检测犬细粒棘球绦虫感染的粪抗原.首先提取Eg成虫表膜抗原,制备抗Eg成虫表膜抗原的血清,然后用间接ELISA和Western blotting方法检测其抗原抗体反应及免疫原性,用间接免疫组化方法对Eg成虫表膜蛋白进行组织定位.利...     

The Marek��s disease virus (MDV) protein encoded by the UL17 ortholog is essential for virus growth

Marek’s disease virus type 1 (MDV-1) shows a strict dependency on the direct cell-to-cell spread for its propagation in cell culture. As MDV-1 shows an impaired nuclear egress in cell culture, we wished to address the characterization of capsid/tegument genes which may intervene in the maturation of intranuclear capsids. Orthologs of UL17 are present in all herpesviruses and, in all reported case, were shown to be essential for viral growth, playing a role in capsid maturation and DNA packaging. As only HSV-1 and PrV UL17 proteins have been characterized so far, we wished to examine the role of MDV-1 pUL17 in virus replication. To analyze MDV-1 UL17 gene function, we created deletion mutants or point mutated the open reading frame (ORF) to interrupt its coding phase. We established that a functional ORF UL17 is indispensable for MDV-1 growth. We chose to characterize the virally encoded protein by tagging the 729 amino-acid long protein with a repeat of the HA peptide that was fused to its C-terminus. Protein pUL17 was identified in infected cell extracts as an 82 kDa protein which localized to the nucleus, colocalizing with VP5, the major capsid protein, and VP13/14, a major tegument protein. By using green fluorescent protein fusion and HA tagged proteins expressed under the cytomegalovirus IE gene enhancer/promoter (P_{CMV IE}), we showed that MDV-1 pUL17 nuclear distribution in infected cells is not an intrinsic property. Although our results strongly suggest that another viral protein retains (or relocate) pUL17 to the nucleus, we report that none of the tegument protein tested so far were able to mediate pUL17 relocation to the nucleus.     

Notes on the occurrence of tubercular spines in Schistosoma margrebowiei and Schistosoma mattheei

Scanning electron microscopical (SEM) studies on the tegument of the bovid schistosomes, Schistosoma margrebowiei and Schistosoma mattheei have yielded conflicting results; certain authors observed the tubercles on the tegument of these species to be spined, while others reported that they are spineless. The present study indicates that the protrusion of tubercular spines is subject to phenotypic plasticity regulated by external factors such as the identity of the host species and whether or not the schistosome is paired.     

鸭病毒性肠炎病毒强毒在人工感染鸭体内形态结构和发生学的电镜观察

为研究鸭病毒性肠炎病毒(DEV)CH强毒株在感染鸭体内的分布和形态学发生规律，应用透射电镜和超薄切片技术对人工感染DEV的成年鸭各组织器官进行观察。结果表明：感染后12h在脾脏和法氏囊首先观察到少量的DEV出现，24h后在脾、胸腺和法氏囊以及死亡鸭的肝、肠和胰中均观察到具有典型的疱疹病毒粒子及其核衣壳形态的DEV。DEV病毒核衣壳有空心型、致密核心型、双环型和内壁附有颗粒型4种形态，存在胞核和胞浆两种装配方式。病毒成熟有两种方式：一为细胞核内核衣壳在核内获得皮层，通过核内膜获得囊膜成为成熟病毒；二为核内核衣壳通过内外核膜进入胞浆，核内和胞浆内的核衣壳在细胞浆中获得皮层，然后在各种质膜上获得囊膜，最后成熟病毒通过细胞破裂或其他方式释放到细胞外。伴随着病毒的复制、装配和成熟，细胞中出现多种核内和胞浆包涵体、核内致密颗粒、核内微管和中空短管、胞浆电子致密小体等结构。     

The morphology of a sensory receptor in the nippled tubercles of Schistosoma mattheei

During scanning electron microscopy (SEM) of the tegument of Schistosoma mattheei, a structure was observed within the nippled tubercles. It is postulated that it is a sensory receptor with a tactile function.     

Early and transient cytotoxic response of peritoneal cells from Fasciola hepatica-infected rats

Experimental infection by F. hepatica was performed on rats. Early recruitment of the peritoneal cell population was observed and revealed transient parasite-killing activity, preceded and followed by a state of total unresponsiveness. The activation peaked at seven days post-infection (dpi) and was characterised by a massive peritoneal cell recruitment, a strong superoxide anion and nitric oxide (NO) production, that were coincident with the fasciolicide activity of these cells, as monitored by an in vitro decrease of juvenile fluke viability in a conditioned medium. The addition of L-NG-monomethyl arginine (LNMMA) to cell cultures abrogated both fasciolicide activity and NO production. Parasites started to die when NO production exceeded 25 microM and all juvenile flukes were killed by a 90 microM NO exposition (Lethal Dose 50 between 45.8 and 50.3 microM, 95% fiducial limits). However, when rat peritoneal cells were cultured in the presence of either infected or control rat serum, juvenile flukes were much more resistant to the oxidative burst, despite a massive attachment of rat peritoneal cells to the parasite tegument. These data suggest that a transient control of fasciolosis may take place in the peritoneum following the parasite intrusion but that the parasite efficiently scavenges the host cellular response to avoid destruction.     

Morphology and histology of the adult Paramphistomum gracile Fischoeder, 1901

In the present study, we evaluated the histological morphology of the adult Paramphistomum (P.) gracile. Adult flukes with bodies 5~15 mm in length and 2~7 mm in width were subjected to histological analysis. Longitudinal and transversal serial-sections were stained with hematoxylin and eosin, and examined. The body surface and longitudinal section of P. gracile were also assessed using scanning electron microscopy. In this species, the anterior sucker and posterior sucker (acetabulum) were present on an anterior and posterior part of the body, respectively. The major folds were located in the areas of the anterior sucker, genital canal, and posterior sucker. The fluke membrane was spineless at the tegument surface and in the tegument tissue. Histological data showed structural-systematic characteristics of the digestive tract, reproductive tract, excretory tract, copulatory organs, connective tissues, and muscle tissues. We attempted to elucidate the histological characteristics of P. gracile that might increase the knowledge and understanding of rumen fluke morphology.     

Immunolocalization of cytoskeletal components in the tegument of the 3-week-old juvenile and adult Fasciola gigantica

Components of three cytoskeletal elements, namely, microtubule, intermediate and actin filaments have been localised in the tegument of the 3-week-old juvenile and adult Fasciola gigantica by means of immunofluorescence and immunoperoxidase techniques, using mouse monoclonal anti-alpha-tubulin, anti-cytokeratin antibodies and biotinylated-phalloidin, respectively. The immunostaining with the above probes were also performed in adult Schistosoma mansoni for comparison. The presence of tubulin, indicative of microtubules, was demonstrated in the tegumental cell bodies, their cytoplasmic processes, and the basal layer of the tegumental syncytium of F. gigantica. While in S. mansoni, tubulin appeared as vertical lines stretching across the whole thickness of the syncytium. Cytokeratin, representing one type of intermediate filaments, was detected in the tegumental cell bodies, their cytoplasmic processes, tegumental syncytium and spines of F. gigantica. In contrast, cytokeratin was evident only in the syncytium of S. mansoni, but not in the spines. Phalloidin, which could bind to actin, a subunit of microfilament, was detected in the tegumental cell bodies, their processes, and the microtrabecular network which form the scaffold of the tegumental syncytium of F. gigantica. In S. mansoni, actin was localized in similar tissues except the syncytium was not stained while spines exhibited intense staining. In F. gigantica, the presence of microtubules and actin filaments in the tegumental cells, their processes and in the syncytium could mediate the movement of secretory granules from the cell bodies towards the basal as well as the apical layer of the tegument. Cytokeratin filaments may serve to reinforce the integrity of the tegumental syncytium as well as the spines.     

青藏高原东部橐吾属植物的花性分配和雌全同株系统

雌全同株是指同一植株内同时拥有雌花和两性花的性系统,至今对该性系统的适应性研究较少。本文以青藏高原东部常见的3种橐吾属植物为材料,调查植株内头状花序的位置,植株高度和个体叶片去除对花性分配的影响。结果表明,3种橐吾均自交不亲和,并且花部特征存在显著的花序轴内变异,无论总状花序基向式发育还是顶向式发育,均表现出早期花有较大的花展示和偏雌的性分配,晚期花拥有较多胚珠和偏雄的性分配。较高的个体拥有较大的花展示,并在雌性功能上投入更多;被去除叶片的个体的花展示和雌花生物量投入均明显下降。然而,植株高度和叶片去除并不会改变花特征在花序内的变异。分析认为橐吾属植株的雌全同株系统的进化意义为资源的灵活分配和吸引传粉者,但无法排除减少雌雄功能冲突的可能。