感染环形泰勒焦虫(Theileria annulata)的牛外周血白细胞的形态观察

用光镜及扫描电镜观察了体外高代培养的含牛焦虫颗粒的牛外周血白细胞的形态及在细胞周期中细胞表面的特征性变化。这种经多年传代的含虫的牛外周血白细胞恢复了分裂和繁殖的能力,目前已成为较稳定的细胞系。细胞表面具多种伪足突起,如叶状、丝状及绒毛状。细胞周期中备期细胞表面的主要特征是:S期:细胞平扁,边缘具薄的时状伪足及丝状伪足;G_2期:细胞中部隆起,表面具少量绒毛状伪足;G_1期:绒毛状结构少或无,而出现丝状及小的叶状伪足,细胞仍保持球形;M期:细胞球形,表面密被以绒毛。作者根据扫描电镜的观察认为光镜下所观察的两类细胞,实际上是反映了一种细胞处于不同发育阶段时的特征。     

The orientation of the magnetic axes of membrane-bound iron-sulfur clusters and a cytochrome b-559 in the green halophilic alga Dunaliella parva

Photosynthetic membrane fragments separated from whole cells of the green alga Dunaliella parva, were oriented by incorporation into multilayers on thin Mylar films. These partially dehydrated films were then examined by EPR spectroscopy for evidence of orientation of paramagnetic components. Five previously identified paramagnetic components, the reduced states of iron-sulfur clusters A and B, the intermediate acceptor X^?, the reduced Rieske iron-sulfur cluster, and oxidized cytochrome b-559, displayed EPR signals showing orientation. In addition, several previously unknown paramagnetic components were also observed to be oriented. Four components, previously characterized in spinach chloroplast preparations, the iron-sulfur clusters A and B, the intermediate acceptor X^?, and cytochrome b-559, were shown to be similar in the green alga, D. parva. The orientations of iron-sulfur clusters A and B, however, were determined unambiguously in this preparation; this was not possible in previous work with spinach. The heme plane orientation of cytochrome b-559 was found to be perpendicular to the membrane plane in agreement with the results in spinach preparations. A new photoinduced EPR signal with g values of 1.88, 1.97 and 2.12 was seen only in the oriented preparations and was indicative of a reduced iron-sulfur cluster with an orientation different from that of iron-sulfur cluster A or B. This suggests the existence of a previously unidentified acceptor in Photosystem I of green plants. These studies clearly show that the orientation of these components in bioenergetic membranes are conserved over a large span of evolutionary development and are, therefore, an important aspect of the mechanism of electron transfer.     

标志技术在研究小皱蝽成虫种群特征中的应用

应用标志－释放－回收技术研究小皱蝽成虫的主要种群特征,结果如下：（１）成虫扩散的偏离度Ｋｕ＝２．４,为一阶峻开曲线;（２）分别用Ｐｅｔｅｒｓｏｎ和Ｊａｃｋｓｏｎ方法对种群蜜度进行了估计,结果表明,Ｊａｃｋｓｏｎ的方法较好;（３）雄虫平均寿命４０－４５,虫平均寿命１２０－１３０。天。     

Chemoprophylaxis with tetracycline drugs in the immunisation of cattle against Theileria annulata infection

Gill B.S., Bhattacharyulu Y., Kaur D. and Singh A. 1978. Chemoprophylaxis with tetracycline drugs in the immunisation of cattle against Theileria annulata infection. International Journal for Parasitology8: 467–469. Three-month-old fully susceptible cross-bred calves were immunised against tropical theileriosis by treating 2-tick or 5-tick stabilate-induced Theileria annulata infections, with 1 or 2 doses of long-acting oxytetracycline (Pfizer) at 20 mg/kg body weight injected subcutaneously, or chlortetracycline at 16 mg/kg body weight daily for 8 days given orally. The treatment began on the day of the infection. After 45 days, the recovered calves were given severe 10-tick homologous stabilate challenge.The reactions were evaluated by noting fever, degree of anaemia, severity of the swelling of the regional lymph node, rate of parasitization of lymphocytes in the lymph node, and of erythrocytes in the peripheral circulation.The untreated calves developed a severe form of the disease with typical symptoms, which killed 1 of 4 and 2 of 5 calves receiving 2-tick and 5-tick stabilates, respectively. A total of 30 treated calves reacted mildly or not at all. Both the treated and untreated, recovered calves resisted completely the challenge infection which killed 3 of 4 susceptible controls. The effect of 1 dose of long-acting oxytetracycline was equal to that of 8 daily treatments with chlortetracycline; 2 doses of the oxytetracycline suppressed almost all clinical responses at immunisation.     

Electron Microscopic Studies of the Development of Kinetes in Theileria annulata Dschunkowsky & Luhs, 1904 (Sporozoa, Piroplasmea)

SYNOPSIS. Gamogony of Theileria annulata Dschunkowsky & Luhs occurs within the intestine of nymphs of the tick Hyalomma anatolicum excavatum Koch. After the 5th day post repletionem (p.r.) of the ticks spherical and ovoid parasites were found within the intestinal cells. These stages were thought to represent fertilized macrogametes. These underwent a transformation process leading ultimately to the differentiation of a motile stage, the kinete , which leaves the intestinal cells on the 14th-17th day p.r. and penetrates the alveoles of the salivary glands. The transformation of the stationary into a motile stage takes place by formation of a growing protrusion (= anlage) into an inner, enlarging vacuole. During this process the limiting membrane of the vacuole serves as the outer membrane of the developing motile stage, whereas the 2 inner membranes of its pellicle are newly formed. The steps of this differentiation in T. annulata are compared to the process of ookinete formation in haemosporina.     

Investigation of Ixodid ticks as vectors of Babesia caballi and Theileria equi (Protozoa: Apicomplexa) in central Italy

Babesia caballi and Theileria equi are widely recognized as causative agents of equine pirolasmosis (EP), an acute, sub‐acute, and chronic disease of equines, with relevant economic impact on horse trade worldwide. Although several studies on EP prevalence from central Italy have been published, data on ticks responsible for its transmission are still lacking. In this study, we identified a potential competent vector, investigating main features of its ecology together with EP infection rates. A two‐year sampling of questing ticks was carried out for the first time in Italy in an area known for high EP prevalence in horse sera, detecting the association between Rhipicephalus bursa and causative agents of EP. Most of the positive pools harbored a single infection (91.1%); mixed infections were also detected (8.9%). The infection rate for T. equi slightly decreased among years; B. caballi showed a lower, but increasing, infection rate. Tick phenology, climate variables, and peaks of EP prevalence indicated late May and second half of June as periods with the highest risk of new infections, especially during warm and dry days.     

Publications of Anthony Calhoun Clement (1909–1984)

Summary

Two zoeae and the megalopa of the majid crab Macropodia parva were obtained from laboratory material. At 25±1°C and 35% salinity, the first crab appeared 12 days after hatching; survival to the first crab instar was 27%. The larval stages are described in detail and compared with those of the previously described species of the genus Macropodia. Zoeal characteristics of M. parva that differentiate it from other known Macropodia larvae are the naked telson furcae and the absence, in zoea II, of the exopodal setae on the basis of the maxillule.     

A panel of microsatellite and minisatellite markers for the characterisation of field isolates of Theileria parva

Mini- and microsatellite sequences show high levels of variation and therefore provide excellent tools for both the genotyping and population genetic analysis of parasites. Herein we describe the identification of a panel of 11 polymorphic microsatellites and 49 polymorphic minisatellites of the protozoan haemoparasite Theileria parva. The PCR products were run on high resolution Spreadex gels on which the alleles were identified and sized. The sequences of the mini- and microsatellites were distributed across the four chromosomes with 16 on chromosome 1, 12 on chromosome 2, 14 on chromosome 3 and 18 on chromosome 4. The primers from the 60 sequences were tested against all the Theileria species that co-infect cattle in East and Southern Africa and were found to be specific for T. parva. In order to demonstrate the utility of these markers, we characterised eight tissue culture isolates of T. parva isolated from cattle in widely separated regions of Eastern and Southern Africa (one from Zambia, one from Uganda, two from Zimbabwe, four from Kenya) and one Kenyan tissue culture isolate from Cape buffalo (Syncerus caffer). The numbers of alleles per locus range from three to eight indicating a high level of diversity between these geographically distinct isolates. We also analysed five isolates from cattle on a single farm at Kakuzi in the central highlands of Kenya and identified a range of one to four alleles per locus. Four of the Kakuzi isolates represented distinct multilocus genotypes while two exhibited identical multilocus genotypes. This indicates a high level of diversity in a single population of T. parva. Cluster analysis of multilocus genotypes from the 14 isolates (using a neighbour joining algorithm) revealed that genetic similarity between isolates was not obviously related to their geographical origin.     

The protozoan parasite, Theileria annulata, induces a distinct acute phase protein response in cattle that is associated with pathology

Acute phase proteins (APP) are synthesised in the liver in response to the systemic presence of high levels of pro-inflammatory cytokines. Bacteria are considered to be strong inducers of APP whereas viruses are weak or non-inducers of APP. Very few reports have been published on APP induction by parasites. Here, we report that the tick-borne protozoan parasite of cattle, Theileria annulata, induced an atypical acute phase response in cattle. Following experimental infection, serum amyloid A (SAA) appeared first, followed by a rise in alpha(1) acid glycoprotein (alpha(1)AGP) in all animals, whereas haptoglobin, which is a major APP in cattle, only appeared in some of the animals, and generally at a low level. All three APP only became elevated around or after the appearance of schizonts in draining lymph nodes and after the first observed temperature rise. Increased alpha(1)AGP levels coincided with the appearance of piroplasms. The production of SAA and alpha(1)AGP correlated strongly with each other, and also with some clinical measures of disease severity including the time to fever, development of leucopaenia, parasitaemia and mortality. These results are consistent with the hypothesis that T. annulata causes severe pathology in susceptible cattle by inducing high levels of pro-inflammatory cytokines.     

Survival of Theileria parva-infected adult Rhipicephalus appendiculatus under laboratory and quasi-natural conditions

Adult Rhipicephalus appendiculatus Muguga, having high or low intensities of Theileria parva Muguga infection in their salivary glands, were exposed to 20 °C and 85% relative humidity in the laboratory or quasi-natural conditions. Survival of the ticks and T. parva infections in their salivary glands was then monitored over a two year period. Ticks, having an average infection level of 2 infected acini per female, survived for up to 70 or 106 weeks after moulting under the laboratory or quasi-natural conditions respectively. Those having an infection level of 26 infected acini per female, survived for a similar duration except that those under quasi-natural conditions survived for a slightly shorter duration (102 weeks). Similarly, T. parva parasites survived for much longer periods under quasi-natural conditions than under the laboratory conditions. They survived for up to 38 or 78 weeks post salivary gland infection under the laboratory or quasi-natural conditions respectively in both categories of infection levels. There was apparently a density dependent relationship in T. parva survival, with a dramatic fall in infection occurring in ticks with high levels of infection between weeks 10 and 18 or weeks 38 and 46 post salivary gland infection in those exposed to laboratory or quasi-natural conditions before levelling off. This revised version was published online in July 2006 with corrections to the Cover Date.