bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative and qualitative change in production of excretions/secretions byLitomosoides cariniiduring development in the jird (Meriones unguiculatus)
Authors: Harnett W. , Meghji M. , Worms M. J. , Parkhouse R. M. E.
Published: June 2009

Excretions and secretions (E–S) were collected from a series of developmental stages ofLitomosoides cariniimaintainedin vitro. Measurement of the protein content of E–S obtained from each stage indicates that the rate of production of E–S varies enormously during development of the worm. E–S was iodinated using both Iodogen and the Bolton and Hunter Reagent and was also biosynthetically labelled by incubating worms in the presence of [35S]methionine and [3H]leucine. Attempts to biosynthetically label E–S of mature worms and microfilariae with [3H]glucose were unsuccessful. Examination of radio-isotope labelled E–S by SDS–PAGE revealed that some components were sex specific and that the differences in total E–S production during development were due to the existence of both stage-specific components and components whose rate of release varied during parasite maturation. Antigenic characterization of E–S, carried out by immunoprecipitation in combination with SDS–PAGE, indicated that E–S consists of immunogenic components, a molecule which is probably a non-immunogenic parasite product, and host albumin. The implications of these findings for the construction of diagnostic tests to detect products of human filarial parasites are discussed.
Population regulation in ticks: the role of acquired resistance in natural and unnatural hosts
Authors: Randolph Sarah E.
Published: June 2009

Attachment, engorgement and subsequent development of successive infestations ofIxodes triangulicepslarvae and nymphs on natural hosts,Apodemus sylvaticus, and unnatural hosts, laboratory mice, are compared. In laboratory mice, primary infestations above a threshold level of about 10 ticks elicit an immunological response which reduces, in a density-dependent manner, the rate of successful tick engorgement during subsequent infestations. In contrast, inA. sylvaticussuccessive infestations of larvae result in unchanged or slightly improved survival through to nymphs. The relevance of these results to the concept of host-parasite co-evolution and to tick population regulation is discussed.
Immune expulsion of Trichuris muris from mice during a primary infection: analysis of the components involved
Authors: Wakelin D.
Published: June 2009

Immune serum accelerated the expulsion of Trichuris muris when transferred into normal mice on days 0 and 3 after infection, but had no effect when the recipient mice had been immunosuppressed by sublethal irradiation or by cortisone treatment. Delaying serum transfer until days 7 and 8 in normal mice failed to accelerate expulsion, although immune mesenteric lymph node cells (MLNC) accelerated expulsion whether transferred early or late in infection.

Expulsion from NIH mice, normally complete by 12 days, was prevented by sublethal irradiation given as late as 9 days after infection, but could be restored by subsequent transfer of immune MLNC or, to a lesser degree, non-immune MLNC. Immune MLNC were unable to restore worm expulsion in mice irradiated before infection.

These results are interpreted as showing that the immune expulsion of T. muris from mice during a primary infection requires the sequential activities of antibody-mediated and lymphoid cell-mediated components.
Problems arising after a new compound has shown proven activity in the laboratory
Authors: Neal R. A.
Published: June 2009

Starting with the work showing activity in the research programme (Table 1), compounds will usually have been entered for various reasons, first into the in vitro testing systems, or more rarely into the in vivo system unless this is the only testing system available for that particular organism.
The pathology induced in laboratory rats by metacestodes ofTaenia crassicepsandMesocestoides corti(Cestoda)
Authors: Chernin J. , McLaren Diane J.
Published: June 2009

Sprague–Dawley rats were infected by intraperitoneal injection with either the cysticerci ofTaenia crassicepsor the tetrathyridia ofMesocestoides corti. Both species of metacestodes reproduce asexually in the peritoneal cavity. The effect ofT. crassicepsupon the rats was to cause chronic inflammation of the peritoneum, fibrous adhesions between the visceral organs and hyperplasia of the gut mesenteries which became extended into a large sac-like structure. Dead parasites surrounded by white calcareous material were found free in the peritoneum and attached to the inner body wall and viscera. The histopathology of the hyperplastic mesenteries and fibrous membrane is described. The tetrathyridia ofM. cortiwere found free in the peritoneal cavity as well as in the liver (mainly the left liver-lobe), gut mesenteries and in an outgrowth of the connective tissue associated with the pancreas. The connective tissue outgrowth comprised 2 layers; an inner reticular layer and a thickened marginal layer. Metacestodes were found in collagen—fibrin capsules within the connective tissue. A layer of mucopolysaccharide material was interposed between the parasite and the capsule wall. A possible method by which the parasites gain entry into the connective tissue is described. The connective tissues of rats harbouring eitherM. cortiorT. crassicepshad increased numbers of mast cells compared to connective tissues from control rats. Younger mast cells containing biogenic amines predominated in infected tissues whereas older heparin-containing cells dominated control tissues.
The host-parasite relationship of Schistosoma japonicum in CBA mice
Authors: Moloney N. A. , Webbe G.
Published: June 2009

The host–parasite relationship of the Chinese mainland strain of Schistosoma japonicum in CBA mice is described and compared to previous reports on this parasite in mice. S. japonicum took under 2 weeks to complete its migration to the portal system of mice, and peak passage of schistosomula through the lungs occurred 5–6 days after infection. The mean percentage establishment of worms, which was independent of the infecting inoculum, was 46%. The adult worm burdens remained constant over a 28-week period of infection. Male and female worms reached maximum mean lengths of 13 and 19 mm, respectively. Egg laying commenced 30 days after infection. The number of ova deposited in the liver stabilized at some 55000 by 12 weeks of infection with 30 cercariae, but the intestinal egg burden rose from 132000 at 12 weeks to 430000 at 28 weeks. Faecal eggs were first observed 6 weeks after mice were exposed to 100 cercariae and 7 weeks after lighter exposures. Faecal egg output also stabilized 12 weeks after infection. The formation of granulomas in the liver occurred within 2 weeks of egg deposition and encompassed a maximum area 14 weeks after infection. Fifty per cent mortality occurred 15 weeks after exposure, but only in hosts infected with 100 cercariae.
Strongyloides ratti: studies of 75Se-labelled larvae of the homogonic strain in female hosts
Authors: Wilson P. A. G. , Simpson Norma E.
Published: June 2009

A prediction of the hypothesis of Wilson (1977, 1980a, b) to account for larval migration of homogonic Strongyloides ratti in the host is that the pattern of invasion of the mammary gland of a lactating rat will be quantitatively similar on both sides and independent of the point of entry into the body. Twenty-one suckled mother rats in 6 experiments in which live 75Se-labelled 3rd-stage homogonic larvae were injected under the skin of the upper flank had an overall distribution of label 30 h post-injection, as a percentage of the initial dose, in the quadrants, I (rear, injection side), II (rear, opposite injection side), III (front, injection side) and IV (front, opposite injection side) of the mammary gland as follows: 27·4%, 1·27%, 1·89% and 1·24%. Quantitative changes in mammary label between 30 and 48 h post-injection using live larvae, differences between mothers and virgins, and results after injection of heat-killed labelled larvae, confirm that the pattern is representative of the behaviour of normal (unlabelled) worms when injected. The theory is therefore disproved. The findings are put forward as the first quantitative evidence for major lymphatic involvement in migration of a skin-penetrating round worm. They need confirmation in similar experiments in which worms are allowed to penetrate the skin naturally. The role of isotope-labelled larvae versus traditional methods of estimating parasite content of host tissue is discussed.
Quantitative methods in the study of the pathogenesis of haemoprotozoal diseases
Authors: Losos G. J. , McMillan I. , Minder Ch. E. , Soulsby K.
Published: June 2009

The study of pathogenicity of haemoprotozoa and the pathogenesis of the diseases they cause requires quantitative descriptions. Statistical and mathematical methods are introduced to describe infectivity, parasitaemia, total body parasitosis and the severity of diseases.
Factors affecting surface changes in intact cercariae and cercarial bodies of Schistosoma mansoni
Authors: Pinto-Ramalho F. J. , Gazzinelli G. , Howells R. E. , Pellegrino J.
Published: June 2009

The effect of different incubation media and of temperature on the induction of water sensitivity has been investigated in intact and tailless Schistosoma mansoni cercariae. Removal of the cercarial tail by vortex stirring and elevation of the temperature of the medium from 27 to 37°C resulted in the rapid onset of permeability changes in the larvae. The rate of change was greater in water than in TC-199 or Hanks' BSS media. Lowering the pH of the medium or increasing the concentration of Ca2+ ions decreased the rate of permeability change: raising the pH of the medium or the addition of 10−5 M EDTA enhanced the rate.

Raising the temperature of the medium also increased the rate of permeability change in intact cercariae although the rates obtained varied with the different media tested, being greatest in TC-199.

It is concluded that both temperature elevation and loss of the cercarial tail influence the onset and rate of permeability changes in cercarial bodies during the transformation to schistosomula.
The duration of passive protection against Taenia ovis larvae in lambs
Authors: Heath D. D. , Yong W. K. , Osborn P. J. , Parmeter S. N. , Lawrence S. B. , Twaalfhoven H.
Published: June 2009

In an attempt to induce passive protection in lambs against Taenia ovis larvae that would last for the 15–20 weeks from birth to slaughter as fat lambs, one group of ewes was immunized by a series of injections of 2000, 4000, 8000, 16000 and 32000 activated oncospheres of Taenia ovis prior to parturition. Another group of ewes was not immunized. All ewes had previously grazed pasture lightly infected with T. ovis eggs. Most lambs from non-immunized ewes developed cysts after oral infection with T. ovis eggs. However, no lambs from immunized ewes developed cysts up to and including 6 weeks after birth. Between 8 and 16 weeks after birth a proportion of lambs were found to be susceptible to infection. By 18 weeks after birth all lambs were apparently susceptible. The 99% confidence band for the mean duration of demonstrable complement-fixing antibody titres was 6·2–7·8 weeks for lambs from immunized ewes. The persistence of maternal protective antibody in some lambs could possibly preclude successful active immunization of all lambs against T. ovis larvae before 18 weeks of age.
The species of Eimeria in rabbits for meat production in Britain
Authors: Catchpole Janet , Norton C. C.
Published: June 2009

Eight species of coccidia were recognized in 596 faeces samples from 3 commercial rabbitries in South East England. The level of infection was related to management methods and at one site it was reduced by an outbreak of mucoid enteritis and/or its treatment with oxytetracycline. In samples from rabbits managed conventionally in wire cages over droppings-pits, 96% contained oocysts and of these, 60% had 1000–10000 oocysts/g. Mixed infections were common, 67% of the animals carrying 2–4 different species. Eimeria media, E. magna and E. perforans occurred most frequently; E. coecicola, E. irresidua and E. flavescens were less common and E. intestinalis and E. piriformis were relatively rare. E. stiedai was not recorded.
Brittlestar host specificity and apparent host discrimination by the parasitic copepod Ophiopsyllus reductus
Authors: Emson R. H. , Mladenov P. V.
Published: June 2009

Host specificity of a siphonostome copepod Ophiopsyllus reductus was confirmed by the results of an extensive survey of co-existing possible alternate host brittlestars. The parasite was found only on Ophiocomella ophiactoides. The ability to discriminate between potential hosts was tested experimentally. O. ophiactoides was always preferred and, in experiments with unrelated alternative hosts, the discrimination was absolute. When closely related species were the alternate host, discrimination was less complete. It is suggested that the discrimination is due to recognition of either tactile or chemical characteristics of the preferred host.
Parasite-mediated reductions in the growth of nymphal backswimmers
Authors: Lanciani C. A. , May P. G.
Published: June 2009

Engorged, parasitic water mites were observed to decrease the growth rate and to increase the stadium length of nymphal backswimmers. Unengorged mites were found to have no effect on the host. The extended stadium lengths of parasitized hosts should reduce the instantaneous rate of natural increase of populations of parasitized hosts because this rate is sensitive to any factor that delays the onset of reproduction.
Observations on tanning of the potato cyst-nematode,Globodera rostochiensis
Authors: Awan F. A. , Hominick W. M.
Published: June 2009

Colour changes that occur during tanning of intact and puncturedGlobodera rostochiensisfemales and of isolated cuticle are described. Experiments with catechol and enzyme inhibitors show that the tanning enzyme, a phenoloxidase, is located in the cuticle, soluble in aqueous media and relatively abundant. Substrate for the enzyme is limited in the cuticle. Pseudocoelomic fluid of yellow females promoted tanning and contains either phenolic substrate(s) for the enzyme or part of a biochemical system responsible for release of the substrate. The substrate or biochemical system is thermolabile. Apparently, the tanning enzyme and its substrate(s) are partitioned in living females but the partitioning breaks down after death and the cuticle tans to form the cyst.
Viruses–exploiters or dependants of the host?
Authors: Newton Alison A.
Published: June 2009

Viruses are frequently referred to as the supreme parasites and yet it is now more than 20 years since any paper on this topic was published inParasitology. This deficiency probably reflects the great emphasis placed during the last two decades on those aspects of virology christened by Sir Christopher Andrewes ‘dream virology’ (Andrewes, 1973), namely the molecular and genetic properties of viruses, in contrast to the more clinical and biological aspects of ‘steam’ virology. Many modern virologists select a virus as a convenient model system with which to investigate such things as genetic organization or control of transcription, with little regard for the interaction with the host cell that supports its replication. Paradoxically, it is this very emphasis on the detailed molecular mechanisms of virus replication that has now put us in a better position to understand the relationships between these highly specialized parasites and their host systems than for any other type of parasite. Recent advances in cell biology coupled with an understanding of the molecular basis of viral replicative mechanisms mean that new insight is possible into the interactions of a virus with its host. For example, we are just beginning to appreciate why a virus should infect one individual and not another, or why it should multiply only in certain tissues at certain stages of development of a multicellular organism. Indeed, study of such tropisms may frequently tell us as much about the host cell as about the virus.
A rapid chromatographic method for elimination of fungal contamination in in vitro cultures of Leishmania spp
Authors: Okot-Kotber B. M.
Published: June 2009

It was demonstrated that antimycotic agents are unsuitable for elimination of mycotic contamination in in vitro cultures of Leishmania spp. Ion-exchange chromatography was designed to separate the protozoan parasites from the contaminating yeast or fungal cells based on their surface net charges. The method was found to be efficient and rapid, and would also reduce bacterial contamination in cultures which have been exposed to both contaminants Viability of the cells has been shown to be unaltered by this treatment as demonstrated by their ability to multiply rapidly in culture medium, as was seen in the controls.
An ultrastructural examination of irradiated, immunizing schistosomula ofSchistosoma mansoniduring their extended stay in the lungs
Authors: Mastin Avis , Bickle Q. D. , Wilson R. A.
Published: June 2009

An ultrastructural study has been performed on radiation-attenuated parasites fixedin situduring their extended stay in the lungs. At day 7 post-infection all parasites were located within blood vessels. In contrast to normally migrating parasites, at days 13 and 21 post-infection the majority of radiation-attenuated parasites were lying free within alveoli. As far as could be seen, radiation-attenuated parasites had undergone the normal develop mental changes associated with the lung stage of migration. These included elongation of the body and loss of mid-body spines and the fibrous layer beneath the tegument. No ultrastructural evidence was found to suggest why schistosomula failed to migrate further and instead burst into alveoli. No parasites observed on day 7 post-infection were associated with a host inflammatory reaction. At day 13, inflammation was noticeable but could have been a response as much to pulmonary tissue damage as to the presence of parasites. At day 21 post-infection some parasites were internally disrupted but were not associated with host inflammatory reactions and had intact tegumental surfaces – all facts consistent with death by autophagy. One parasite was observed at day 21 with an adherent neutrophil infiltrate and extensive tegumental damage. The relevance of persisting lung-stage parasites to the induction of resistance to challenge is discussed.
Responses of the plant parasitic nematodesRotylenchulus reniformis, Anguina agrostisandMeloidogyne javanicato chemical attractants
Authors: Riddle D. L. , Bird A. F.
Published: June 2009

Rotylenchulus reniformis, Anguina agrostisandMeloidogyne javanicarespond differently to gradients of chemical attractants. In chemotaxis assays performed on agarose plates,R. reniformisL2larvae oriented their movement to several common inorganic salts, cyclic AMP and AMP, as well as to germinated host plant seeds.M. javanicaL2larvae were attracted to germinated seeds, but not to the salts tested, andA. agrostisdauer larvae were not strongly attracted to any of 12 different tested agents, including host root or shoot tips. Attraction ofR. reniformisto salts was measured by comparing different pairwise combinations of ions at equivalent concentrations. The indicated order of attractiveness was: Cl−> Na+> C2H3O2−> Mg2+, NH4+, SO42−. The least attractive salts, (NH4)2SO4and MgSO4, were weakly attractive at an orientation threshold of 1 mm, whereas the most attractive salt, MgCl2, was strongly attractive at a threshold of 0·2 mM Cl−. 3′, 5′ cyclic AMP was strongly attractive at a threshold of 0·05 mM, whereas 5′-AMP was a weak attractant. Some of these responses may affect the distribution ofR. reniformisin its natural environment.
Amplification of the cestode surface: a stereological analysis
Authors: Threadgold L. T. , Robinson A.
Published: June 2009

A stereological study was undertaken on the length, diameter and numbers of microtriches and on the structural and functional amplification factors of the adult cestodes, Hymenolepis diminuta, Hymenolepis nana, Eubothrium crassium, Proteocephalus pollanicoli, the plerocercoid of Schistocephalus solidus and the cysticercus of Taenia crassiceps. The study showed wide variations in these stereological parameters between species, stages and regionally in the same species. A comparison of the present results with previous studies has shown a large measure of agreement but some differences are evident and possible explanations of these differences are proposed.
An analysis of the proteinases ofTrichomonas vaginalisby polyacrylamide gel electrophoresis
Authors: Coombs G. H. , North M. J.
Published: June 2009

The proteinases ofTrichomonas vaginalishave been analysed by electrophoresis in polyacrylamide gels containing denatured haemoglobin. Seven bands of activity were detected indicating multiple proteinases. All of the enzymes were stimulated by 1 mM dithiothreitol and had inhibitor sensitivities characteristic of cysteine proteinases. The enzymes differed significantly, however, with respect to pH optima and relative sensitivities to inhibitors.
A study of the sensitivity ofLeishmania donovanipromastigotes and amastigotes to hydrogen peroxide. II. Possible mechanisms involved in protective H2O2scavenging
Authors: Channon Jacqueline Y. , Blackwell Jenefer M.
Published: June 2009

Different hydrogen peroxide (H2O2)-scavenging mechanisms, and the conditions under which they operate, have been examined in promastigotes and amastigotes ofLeishmania donovani. For promastigotes, the ability of the parasite to remove H2O2was completely ablated by sonication whereas for sonicated amastigotes substantial loss of H2O2from the phagocyte-fre¸e test system still occurred. In direct contrast, the ability of amastigotes, but not promastigotes, to remove H2O2was markedly inhibited by aminotriazole or sodium azide. This suggested a role for haem-containing enzymes, catalase or peroxidases, as a protective H2O2-scavenging mechanism and was consistent with detection of catalase in amastigotes but not promastigotes using a spectrophotometric assay. Both forms of the parasite did, however, show reduced ability to remove H2O2at 5–7°C indicating that additional enzymatic scavenging mechanisms may operate. Glutathione peroxidase activity was undetectable in either form of the parasite. The total thiol sink, glutathione (GSH) plus protein thiols, was greater in promastigotes but the ability to regenerate GSH via glutathione reductase was equivalent for promastigotes and amastigotes. Less temperature-dependent non-enzymatic mechanisms (e.g. an unsaturated lipid sink) also appear to contribute to removal of H2O2by both promastigotes and amastigotes. It seems likely, nevertheless, that the difference in H2O2sensitivity between the two forms of the parasite relates to the activity of the direct H2O2-scavenging enzyme, catalase, which appears to operate more efficiently against a bolus of reagent H2O2.
The population dynamics of competition between parasites
Authors: Dobson A. P.
Published: June 2009

A number of published studies of competition between parasite species are examined and compared. It is suggested that two general levels of interaction are discernible: these correspond to the two levels of competition recognized by workers studying free-living animals and plants: ‘exploitation’ and ‘interference’ competition. The former may be defined as the joint utilization of a host species by two or more parasite species, while the latter occurs when antagonistic mechanisms are utilized by one species either to reduce the survival or fecundity of a second species or to displace it from a preferred site of attachment. Data illustrating both levels of interaction are collated from a survey of the published literature and these suggest that interference competition invariably operates asymmetrically. The data are also used to estimate a number of population parameters which are important in determining the impact of competition at the population level. Theoretical models of host-parasite associations for both classes of competition are used to examine the expected patterns of population dynamics that will be exhibited by simple two-species communities of parasites that utilize the same host population. The analysis suggests that the most important factor allowing competing species of parasites to coexist is the statistical distribution of the parasites within the host population. A joint stable equilibrium should be possible if both species are aggregated in their distribution. The size of the parasite burdens at equilibrium is then determined by other life-history parameters such as pathogenicity, rates of resource utilization and antagonistic ability. Comparison of these theoretical expectations with a variety of sets of empirical data forms the basis for a discussion about the importance of competition in natural parasite populations. The models are used to assess quantitatively the potential for using competing parasite species as biological control agents for pathogens of economic or medical importance. The most important criterion for identifying a successful control agent is an ability to infect a high proportion of the host population. If such a parasite species also exhibits an intermediate level of pathology or an efficient ability to utilize shared common resources, antagonistic interactions between the parasite species contribute only secondarily to the success of the control. Competition in parasites is compared with competition in free-living animals and plants. The comparison suggests further experimental tests which may help to assess the importance of competition in determining the structure of more complex parasite-host communities.
The epidemiology of Ascaris lumbricoides and other soil-transmitted helminths in primary school children from Ile-Ife, Nigeria
Authors: Holland Celia V. , Asaolu S. O. , Crompton D. W. T. , Stoddart R. C. , Macdonald R. , Torimiro S. E. A.
Published: June 2009

An epidemiological survey of intestinal helminthiases was conducted on 766 primary school children aged 5–16 years from Ile-Ife, Nigeria. On the basis of stool examinations, the prevalence of Ascaris lumbricoides, Trichuris trichiura, hookworm and Strongyloides stercoralis was 88·5, 84·5, 33·1 and 3% respectively. Intensity of infection was measured indirectly by egg counts for each species of helminth and also by counting worms passed after chemotherapy in the case of A. lumbricoides. The influence of host age and sex on infection levels was assessed. Relationships between the intensities of A. lumbricoides, T. trichiura and hookworm in individual children were identified. After anthelmintic treatment with levamisole, the frequency distribution of A. lumbricoides per host and the relationship between parasite fecundity and worm burden were investigated.
Population genetics ofPlasmodium falciparumwithin a malaria hyperendemic area
Authors: Conway D. J. , McBride J. S.
Published: June 2009

Serotyping with monoclonal antibodies was used to estimate the number and frequencies of allelic variants of two merozoite surface proteins, MSP1 and MSP2, and an exported protein Exp-1, in a sample of 344 clinical isolates ofPlasmodium falciparumfrom an urban region of The Gambia. Represented among the isolates were 36, 8 and 2 alleles of the MSP1, MSP2 and Exp-1 loci respectively. Relative frequencies of these alleles remained stable in the parasite population over the 2 years of the study. A computer program was used to calculate from the frequencies of individual alleles at the three loci, the probable number of different genotypes in samples from the population, assuming random assortment among the loci. No significant difference was found between the expected and the observed genotype diversity. It is concluded that recombination among unlinked loci is a common consequence of sexual reproduction ofP. falciparumin The Gambia. Slightly lower genotype diversity was observed in each of two villages, which may be a consequence of smaller population size compared with the urban region.
The effect ofGiardia lambliatrophozoites on lipolysisin vitro
Authors: Katelaris P. , Seow F. , Ngu M.
Published: June 2009

Infection withGiardia lambliaoften causes only minor mucosal changes to the small intestine yet frank fat malabsorption may still occur. Some evidence suggests abtext-abstract pancreatic exocrine function in subjects with giardiasis although the mechanism and significance of this is unclear. Studies were conductedin vitroto determine the effect ofG. lambliatrophozoites or culture filtrates from the organism on lipolysis of triglyceride by porcine pancreatic lipase. Live trophozoites significantly inhibited lipolysis. The degree of inhibition increased with longer duration of lipase exposure to trophozoites. Total amounts of enzyme inhibited were proportional to enzyme concentration, while the percentage inhibition was greatest at lowest concentration. At a lipase concentration of 1·7 i.u./ml, enzyme activity was reduced by 89·7% compared to controls after incubation for 4 h with trophozoites. The effect was abolished using killed, intact trophozoites. Culture filtrates ofG. lambliadid not inhibit lipolysis. Specificity of the effect was suggested by the failure of another flagellate protozoan,Trichomonas vaginalis, to inhibit lipase. In this assay system the inhibition of lipolysis was not dependent on the bile salt concentration present. The impact of this effectin vivoremains to be determined but it may contribute to fat malabsorption in giardiasis.
Effects of infection with Echinostoma paraensei on the circulating haemocyte population of the host snail Biomphalaria glabrata
Authors: Noda S. , Loker E. S.
Published: June 2009

Circulating haemocytes from Echinostoma paraensei-infected M line Biomphalaria glabrata snails, or from age- and sizematched control snails, were studied on plastic slides with phase-contrast optics. Granulocytes, hyalinocytes, and round cells were consistently present; granulocytes were further categorized as ‘fully spread' (FS) or ‘partially spread' (PS). Among control snails, the relative percentage and estimated number/mm3 of round cells declined significantly with increased snail size, and the corresponding values for both categories of granulocytes increased. At 1 day post-infection (p.i.) with E. paraensei, overall composition of the haemocyte population was relatively unaffected, but by 8 days p.i. infected snails had significantly higher relative percentages of round cells and PS granulocytes than controls. Because a marked increase in the number of circulating haemocytes is also evident by 8 days p.i., infected snails had approximately 12 times more round cells and PS granulocytes/mm3 of haemolymph than did controls. At 30 days p.i. the relative and absolute abundance of PS granulocytes was still significantly elevated, but otherwise haemocyte populations did not differ from control snails. Alterations in granulocyte size in infected snails were also noted. Infection with E. paraensei has a striking impact of circulating haemocyte populations and also increases the relative concentration of haemocytes with less ability to adhere to a foreign surface.
Factors affecting the adhesion of micro-organisms to the surfaces of plant-parasitic nematodes
Authors: Bird A. F. , Bonig Ingrid , Bacic A.
Published: June 2009

The influence of various agents on the adhesion of endospores of Pasteuria penetrans to the nematode Meloidogyne javanica was studied. Similarly, but to a lesser degree, we have also studied the adhesion of conidia of the fungus Dilophospora alopecuri and the coryneform bacterium Clavibacter sp. (syn. Corynebacterium rathayi) to the nematode Anguina agrostis (syn. A. funesta). Reduction in the degree of both spore and conidial attachment following their pre-treatment with periodate and the presence of PAS staining material on spores, conidia and bacteria implicated carbohydrate in these interactions. Tests involving both unbound and FITC-bound lectins demonstrated that wheat germ agglutinin (WGA) can inhibit the degree of attachment of P. penetrans to M. javanica and that this inhibition can be overcome by pre-treatment of the lectin with N, N′-diacetyl chitobiose. Endospores of P. penetrans, amphid and buccal secretions of 2nd-stage larvae of M. javanica and the cuticle and excretory pore secretions of 2nd-stage dauer larvae of A. agrostis bound WGA, indicating that accessible N-acetyl-D-glucosamine residues are present on these structures. Endospores of P. penetrans also bound Con A, indicating the presence of accessible α-D-glucose/α-D-mannose residues on their surface.
Thermal preferences of resistant and susceptible strains ofBiomphalaria glabrata(Gastropoda) exposed toschistosoma mansoni(Trematoda)
Authors: Lefcort H. , Bayne C. J.
Published: June 2009

The thermal preferences of two strains of the snailBiomphalaria glabrata, one resistant to, and one susceptible to, the parasiteSchistosoma mansoniwere determined in an aquatic thermal gradient. Snails were tested without exposure to the parasite, and 2 h and 5 weeks after exposure to trematode miracidia. The mean temperature selected by susceptible strain snails 2 h post-exposure tended to be lower than that of unexposed controls, although this was not statistically significant. In this strain, at 5 weeks post-exposure, the preferred temperature dropped by 1.9±0.5°C. The resistant strain displayed a significant drop of 1.8±0.6°C 2 h post-exposure. These results are consistent with the hypothesis that a drop in mean temperatures selected by snails is due to altered levels of endogenous cytokines such as IL-1 or TNF in association with parasite activation of the snail internal defense system.
Schistosoma mansoni:morphology and ultrastructure of adult worms recovered from cyclosporin A-treated mice
Authors: Munro G. H. , McLaren D. J.
Published: June 2009

Cyclosporin A administered toSchistosoma mansoni-infected mice at around day 20 of infection reduces the worm burden by > 60%, as assessed by portal perfusion on days 28 and 86. Those worms recovered at perfusion have been examined by light and electron microscopy for drug-induced changes in morphology. Gross parasite damage was characterized by massive bolus formation and subsequent herniation of the gut. This event was attributed to the abnormal accumulation of crystalline structures in the lumen; the crystals were closely associated with lipid droplets, and were shown by X-ray micro-analysis to contain iron. Such crystals were seen only rarely in the intestines of control worms, but they too gave small iron peaks when examined by X-ray micro-analysis. In some drug-treated worms the caecal epithelium had ruptured, thereby releasing luminal contents throughout the worm body. In addition, herniations of the gut were seen protruding through the tegument causing surface deformation and disruption of tegumental and parenchymal tissues. The structural integrity of the worm was ultimately compromised allowing access to cytotoxic effector cells of the host. The combined effects of drug action and cellular cytotoxicity presumably account for the very significant levels of worm killing achieved by CsA treatment of the host.
Parasite-specific antibody reponses of responses of ruminants infected withTrypanosoma vivax
Authors: Vos G. J. , Gardiner P. R.
Published: June 2009

Sera from goats and cattle that were infected with twoTrypanosoma vivaxclones (ILDat 1.2 and ILDat 2.1) derived from different stocks were analysed for antibody activity against the variable surface glycoproteins (VSGs) of the infecting clones by enzyme-linked immune assays (ELISA) and immune lysis. To obtain purified VSG, lysed trypanosomes were separated on dodecyl sulphate-polyacrylamide gels. The gels were copper stained and the VSG protein band was excised from the gel. After destaining, the proteins were electroeluted from the gel slices and used as antigens in ELISA. High titres of IgM and IgG1antibodies and lytic antibodies against the VSG of the infecting clone were detected. The IgG1response appeared about 4 days later than the IgM response. IgG2antibodies were only detected in goats and cattle that were infected with ILDat 1.2. Two goats and two calves that were infected with ILDat 1.2 showed recurrent peaks in lytic activity and of IgM and IgG1antibody activity to the VSG of the infecting variable antigenic type (VAT). Two goats that were infected with ILDat 2.1 showed a similar pattern, but in two other goats there was a recurrent peak only in the IgM class. Recurrent peaks of antibody activity to the VSG of ILDat 1.2 and ILDat 2.1 were not detected in the sera of goats that had been inoculated with irradiated trypanosomes or that had been infected with an unrelatedT. vivaxclone. The recurrence of antibody peaks against the VSG of infecting VATs suggests that trypanosomes with completely or partially identical surface determinants reappear duringT. vivaxinfection of ruminants.
The effect of Babesia microti on feeding and survival in its tick vector, Ixodes trianguliceps
Authors: Randolph S. E.
Published: June 2009

Evidence is presented that Babesia microti may promote its transmission amongst rodents by enhancing the feeding success and survival of its tick vector, Ixodes trianguliceps. Both the mean engorged weight of larval ticks and the percentage moult of larvae to nymphs increased as larvae fed on naive hosts later in the parasitaemic cycle up to a point a few days beyond the loss of a patent infection. This increased feeding success and survival was not dependent on the level of infection by B. microti. Two possible, host-mediated mechanisms for the observed parasite–vector interactions are suggested, the anti-haemostatic effects induced by babesiosis and the interaction of the immunosuppressive effects of Babesia and the development of immunity to ixodid ticks by their vertebrate hosts.
A new species of Leishmania isolated from the great gerbil Rhombomys opimus
Authors: Strelkova M. V. , Shurkhal A. V. , Kellina O. I. , Eliseev L. N. , Evans D. A. , Peters W. , Chapman C. J. , Leblancq S. M. , Van Eys G. J. J. M.
Published: June 2009

Leishmania turanica n.sp., found infecting the desert rodent Rhombomys opimus in the southern territories of the USSR and the Mongolian People's Republic, is described. This parasite exists sympatrically with L. major and L. gerbilli in R. opimus and is the predominant species. A total of 284 isolates of L. turanica from R. opimus, 3 from naturally infected Phlebotomus andrejevi and 1 from P. papatasi were characterized and found to be clearly distinguishable on isoenzyme and nuclear DNA characteristics from all other Old World taxa of Leishmania.
Relocation of Schistosoma mansoni in the lungs and resistance to reinfection in Rattus rattus
Authors: Imbert-Establet D. , Combes C.
Published: June 2009

The localization of adult Schistosoma mansoni originating from Guadeloupe (West Indies) was analysed in the natural host Rattus rattus in experimental and natural infections. A transfer of schistosomes from the porto-mesenteric system to the lungs occurs between the 4th and the 20th weeks post-infection, with a peak between 4 and 8 weeks; it should be noted that the worms start laying eggs at 4 weeks post-infection. In both experimentally and naturally infected R. rattus the relocation of schistosomes in the lungs is correlated with the total worm burden. Between 6 and 12 weeks post-infection some adult worms and numerous eggs are trapped in the liver. A high mortality in the worm population coincides with the migration of the parasites from the porto-mesenteric veins to the lungs. In re-infected R. rattus a relationship appears between the presence of schistosomes in the lungs and resistance to reinfection. It is concluded that, as already postulated previously in mice, resistance to re-infection in the natural host R. rattus is at least partly correlated with the hepatic pathology caused by the schistosomes of the primary infection.
DNA comparisons of Trypanosoma evansi (Indonesia) and Trypanosoma brucei spp.
Authors: Artama W. T. , Agey M. W. , Donelson J. E.
Published: June 2009

Two clones from separate isolates of Trypanosoma evansi in Indonesia were found by polymerase chain reaction (PCR) analyses to contain 3 different repeated nuclear DNA sequences of Trypanosoma brucei spp: the consensus sequence for a highly repetitive 177 base pairs and the gene repeats encoding procyclin and the spliced leader. In addition, the 994 bp minicircle sequence of one of the clones was determined, and PCR amplification primers specific for minicircles of T. evansi were identified that do not amplify minicircle sequences in the T. brucei spp. clones tested.
Development and survival of the free-living stages of Trichostrongylus tenuis, a caecal parasite of red grouse Lagopus lagopus scoticus
Authors: Shaw J. L. , Moss R. , Pike A. W.
Published: June 2009

In the laboratory, yields of infective 3rd-stage larvae of Trichostrongylus tenuis were determined by temperature when moisture was adequate. On the moor, eggs in caecal faeces did not develop to infective larvae during the winter. In summer, development did occur and yields of infective larvae were related to temperature: greatest yields were obtained when mean monthly soil surface temperatures ranged between 76 and 103°C. Rainfall was unimportant, as was desiccation. During summer the mean monthly mortality of infective larvae was 44% but over winter survival was negligible.
An extended proof of migration routes of immature parasites inside hosts: pathways of Nippostrongylus brasiliensis and Strongyloides ratti in the rat are mutually exclusive
Authors: Tindall N. R. , Wilson P. A. G.
Published: June 2009

Rigorous proofs applicable to the routes of migration of Strongyloides ratti and Nippostrongylus brasiliensis skin-penetrating juveniles inside the rat are extended. By applying the inequality principle (Tindall & Wilson, 1988) it was confirmed with a probability of error of I in 1010 that N. brasiliensis larvae applied to the skin passed through the lungs on their way to the intestine. Taking the analysis further, migrating larvae of S. ratti or N. brasiliensis were extracted from the nose or lungs, respectively, of donor rats and transferred to recipients by stomach tube to assay their ability to colonize the intestine. Results showed that (a) changes undergone by each parasite in its proven, specific transit site were essential before larvae could establish in the intestines of recipients, (b) these changes were not completed until larvae had been in the nose or lung for a significant period.
Cloning and characterization of ribosomal RNA genes from Opisthorchis viverrini
Authors: Korbsrisate S. , Mongkolsuk S. , Haynes J. R. , Wong Q. , Sirisinha S.
Published: June 2009

The ribosomal DNA (rDNA) unit of the liver fluke Opisthorchis viverrini has been cloned and characterized. The results demonstrated that the total length of this unit is approximately 13 kb, containing 4·2 kb of large subunit (LSU) rDNA, 2·0 kb of small subunit (SSU) rDNA, 1·0 kb of transcribed spacer DNA and 5·8 kb of non-transcribed + external transcribed spacer DNA. Examination of the non-transcribed spacer region between different rDNA units showed variation in the restriction sites rather than in the length. Judging from hybridization of the rDNA plasmid to the restriction endonuclease digest of genomic DNA, rDNA units represent 6·1% of the total genomic DNA. At the RNA level, the LSU rRNA of O. viverrini and Fasciola gigantica contained a hidden break. The molecule consisted of two fragments co-migrating with a SSU rRNA, when electrophoresis was carried out under denaturing conditions. Ribosomal RNA sequence comparison has been previously used to determine phylogenetic classification of parasitic organisms. The sequence of 381 nucleotides at the 5′ terminus of the LSU rRNA gene was determined and compared with those from species previously reported by other investigators. Phylogenetic classification of O. viverrini, as determined by rRNA gene sequence comparison, is comparable with the conventional taxonomic classification.
The effect of temperature on times to hatching of eggs of the nematode Ostertagia circumcincta
Authors: Young R. R. , Anderson N. , Overend D. , Tweedie R. L. , Malafant K. W. J. , Preston G. A. N.
Published: June 2009

A delayed gamma distribution satisfactorily described the distribution of times to hatching of Ostertagia circumcincta eggs incubated in 0·1% saline at temperatures between 6 and 20 °C. Below 6 °C hatching of eggs was extremely variable. The relationship between rates of development and temperature within the range 10 to 20 °C was more closely described by a non-linear function than a linear one. The non-linear function was incorporated into a temperature summation equation which satisfactorily predicted the hatching of eggs incubated under conditions of alternating temperatures.
Studies on the life-cycle of Himasthla militaris(Trematoda: Echinostomatidae)
Authors: Vanoverschelde R. , Vaes F.
Published: June 2009

In this study two aspects of the biology of the cercaria of Himasthla militaris were examined. Firstly, the cercarial emergence from the first intermediate host, Hydrobia stagnorum, was studied. On a 9 h light (9L)/15 h dark (15D) schedule cercariae of Himasthla militaris emerged from naturally infected Hydrobia stagnorum predominantly during darkness. Inversion of the photo-period resulted in an immediate reversal of the emergence pattern. A comparison between the cercarial release patterns under natural conditions and in a constant light/temperature environment showed that an endogenous as well as an exogenous factor is controlling this process. Secondly, the penetration of the cercaria in Nereis diversicolor and the site-finding of the larva within this second intermediate host was investigated. After a short external migration on the body of N. diversicolor the cercaria enters the polychaete via the anus opening, perforates the gut-wall and moves through the coelom to the anterior segments to encyst in the muscle tissue. This internal migration results in a specific distribution pattern of the metacercariae, with more than 50% of the cysts localized in the first 12 segments and a maximum in segment number 9 (13·8%).
In vivoregulation ofS. japonicagranuloma formation by an IL-2 antagonist
Authors: Kresina T. F.
Published: June 2009

The present study shows anin vivorole for interleukin-2 in the formation of hepatic granulomatous inflammation in murineSchistosoma japonicuminfection. Mice which had been administered an inhibitor to interleukin-2 function during acute infection were noted to have reduced cell-mediated immune responses to ConA andS. japonicumsoluble egg antigen (SEA). Lymphoid tissue from these treated mice also have reduced numbers of cells which could be activated by ConA to produce interleukin-2 mRNA as shown byin situhybridization studies. Mice with less activated lymphocytes had, on the average, a 70% reduction in the granulomatous inflammation surrounding eggs deposited in hepatic tissues of acutely infected mice. The data demonstrate that IL-2 is a key factor in the generation of granulomatous inflammation inS. japonicuminfection and suggest that a potential anti-pathology vaccine could be generated based on limiting the presence of IL-2 generated during acute infection.