bluuebunny/crossref_metadata_2025_split huggingface dataset:
Possible evidence for mortality induced by the parasite Apatemon gracilis in a population of brook sticklebacks (Culaea inconstans)
Authors: Gordon D. M. , Rau M. E. 
Published: June 2009

SUMMARYRegular samples made on the 1978 cohort of brook sticklebacks (Culaea inconstans) from a swamp in Ile Perrot, Quebec, Canada were examined for Apatemon gracilis metacercariae. The prevalence of the parasite rapidly reached 100% in the fish population. The mean parasite burden increased from zero to a plateau of about 44 parasites/fish. Over-dispersion of the frequency distribution of parasites in the fish host, as measured by variance to mean ratios, increased to a peak and then decreased significantly while the mean parasite burden remained constant. The effects of parasite burden on the survival of the stickleback host are discussed, as well as the validity of the use of changes in over-dispersion for demonstrating parasite-induced mortality.
The structure and formation of the egg-shell of Syphacia obvelata Rudolphi (Nematoda: Oxyurida)
Authors: Wharton D. A. 
Published: June 2009

SUMMARYThe egg of Syphacia obvelata is a flattened elipsoid. The egg-shell consists of 5 layers: external uterine layer, internal uterine layer, vitelline layer, chitinous layer and lipid layer. An operculum is present at one pole of the egg. The opercular groove consists of a break in the uterine layers and the modification of the chitinous layer by the deposition of lipoprotein material. On the curved side of the egg the uterine layers are modified to form alternate ridges and depressions. Discrete spaces are present in the internal uterine layer between the ridges. These are open to the exterior via pores in the external uterine layer. The structure of the uterine layers is quite different on the flattened side of the egg. The morphology of the reproductive system and the formation of the egg-shell is described. It is suggested that the complex structure of the uterine layers of oxyurids forms by a self-assembly process.
The migration and development of Filaroides hirthi larvae in dogs
Authors: Georgi Jay R. , Fahnestock Glenn R. , Bohm Marguerite F. K. , Adsit Jane C. 
Published: June 2009

SUMMARYThe development of Filaroides hirthi has been shown to proceed through all 5 stages in the lungs of experimental dogs and the attendant morphological changes are described and illustrated. These observations are interpreted as proof that the unhatched larva of F. hirthi is the 1st stage and that the 1st stage is infective. Moults occurred at approximately 1, 2, 6 and 9 days after infection in the lung tissue. Larvae also developed in vitro to the doubly ensheathed 3rd stage which is the stage achieved by heteroxenous metastrongyloids in their molluscan intermediate hosts. The arrival of 1st-stage larvae in the lungs as early as 6h after oral administration and the anatomical distribution of larvae during the first 24 h indicates that larvae are transported from the alimentary tract to the lungs by way of the hepatic portal circulation, the mesenteric lymphatic drainage, or both. First-stage larvae and eggs containing 1st-stage larvae, when injected into the jugular vein, developed into adult F. hirthi lung- worms in the usual 5 week pre-patent period. This was interpreted as demonstrating that the canine alimentary canal, although undoubtedly the normal portal of entry, is not a site of reactions indispensable to the activation or development of the larvae. Eggs containing 1st-stage larvae, when introduced by jugular and portal venous and mesenteric lymphatic routes, yielded equivalent numbers of adult lungworms indicating that neither the hepatic capillary bed nor the mesenteric lymph nodes presented quantitatively significant impediments to their passage. The question is raised whether the mesenteric lymphatics really are the exclusive migration pathways of certain other species of metastrongyloid larvae. The suggestion is made that conventional studies based on the anatomical/time distribution of larvae be supplemented by intravascular experiments like those described in this report, to provide an independent line of evidence.
Parasites inBulinus senegalensis(Mollusca: Planorbidae)and their detection
Authors: Wright C. A. , Rollinson D. , Goll P. H. 
Published: June 2009

SUMMARYIsoelectric focusing studies on enzyme variation between populations of the snailBulinus senegalensisrevealed that parasitic infections in the snails contributed additional bands of enzyme activity, particularly in the glucose phosphate isomerase (GPI) and malate dehydrogenase (MDH) systems. The patterns due to the parasite enzymes were, in most cases, clearly distinct from those of the host and different from each other. Parasites encountered includedSchistosoma haematobium,S. bovis,Paramphistomum microbothrium, another amphistome probably belonging to the group which infect amphibians,Echinostoma revolutum, another echinostome (probablyEchinoparyphiumsp.), strigeids, xiphidiocercariae (these were resolved into 3 distinct types by the enzyme data) and ciliate protozoa. The 7 host populations which were examined showed marked differences in both the prevalence and variety of their parasitic infections and these variations were tentatively related to environmental differences in their respective habitats and to the nature of human contact patterns. Seasonal changes in the parasite fauna were also noted and some of the implications of the parasite load on the host population are briefly mentioned.
Trypanosoma cruzi: separation of broad and slender trypomastigotes using a continuous hypaque gradient
Authors: Schmatz D. M. , Boltz R. C. , Murray P. K. 
Published: June 2009

SUMMARYTrypanosoma cruzitrypomastigotes occur as a mixture of morphologically distinct forms in natural and experimental infections. We have been able to separate mixed populations into slender and broad forms using a continuous gradient composed of 12·5–25·0% hypaque in culture media. Previously, comparisons could only be made by using various strains of T. cruzi which show a predominance of either form. This separation procedure gave recoveries of 88–98% and had no effect on the viability of the parasites. Infectivity studies showed that slender forms were much more infectious to cultured muscle cells than were broad forms. However, studies with macrophages from CFW mice showed both forms to be equally capable of infection. It is concluded that the mechanism by which each form infects host cells is different; slender forms being capable of infecting both by penetration and by phagocytosis, while broad forms are only capable of infecting through phagocytosis.
Miracidia infective for snails derived from eggs laid by adult Schistosoma mansoni in vitro
Authors: Newport G. R. , Weller T. H. 
Published: June 2009

SummaryVarious biological mixtures commonly used as microbiological nutrients were added to a chemically defined medium, containing 0·2% (w/v) albumin, in order to assess their ability to support maturation of eggs deposited by adult Schistosoma mansoni in vitro. Of the supplements tested, only lactalbumin hydrolysate and casein hydrolysate stimulated egg deposition and subsequent egg development in vitro. Upon addition of foetal calf serum, further stimulation was noted only in casein hydrolysate-containing media. The addition of mouse red blood cells did not significantly improve the system. Some miracidia which hatched from eggs derived from casein hydrolysate-fortified cultures displayed normal behavioural characteristics, penetrated susceptible snails and established patent infections. These results provide an experimental system for exploring the nutritional requirements of developing miracidia, and the physiological determinants that influence miracidial penetrative capacity and subsequent ability to develop in a susceptible intermediate host.
Eimeria tenella in chickens: development of resistance to quinolone anticoccidial drugs
Authors: Chapman H. D. 
Published: June 2009

The development of drug resistance by the present Houghton strain of Eimeria tenella to the quinolones, methyl benzoquate and buquinolate, was found to take place after a single experimental passage. The development of resistance was independent of drug selection pressure and showed cross resistance to other quinolones, but not to amprolium and robenidine. When the Weybridge, Beltsville and Elberfeld strains of E. tenella were compared under similar laboratory conditions, the Weybridge and Elberfeld strains developed resistance to methyl benzoquate after 6 passages and the Beltsville after 5. Studies on the response of the Houghton strain to methyl benzoquate and buquinolate revealed that the drugs did not completely control the infection as measured by weight gain and that oocyst production was not suppressed. These observations indicate that the strain had already acquired some resistance to these drugs. This was confirmed by examining the resistance to methyl benzoquate of a culture of the Houghton strain of E. tenella which had been stored frozen in liquid nitrogen since 1969. This showed full sensitivity to the drug and developed resistance after 8 passages. This suggests that drug tolerance has been acquired by the Houghton strain since 1969.Oocyst lines were established from the Houghton strain by infecting single birds with approximately 10 oocysts. Eleven of these lines were found to be sensitive to methyl benzoquate, and nine to give rise to resistant parasites. It is concluded that the Houghton strain is contaminated by a small number of resistant oocysts which can be eliminated from a culture by dilution of the challenge inoculum. One of these Houghton oocyst lines, sensitive to methyl benzoquate, developed resistance after 8 serial passages.
The fine structure of the developing macrogamete of Eimeria maxima
Authors: Pittilo R. M. , Ball S. J. 
Published: June 2009

SUMMARYThe fine structure of the developing macrogamete of Eimeria maxima was studied from chicks killed at intervals from 138 to 147 h after inoculation. The macrogamete developed within a parasitophorous vacuole. Lying within this vacuole and extending for some distance around the periphery of the macrogamete were intravacuolar tubules, grouped in certain areas, and in some cases they were seen to make direct connexions with the cytoplasm of the parasite. During development, electron-pale vesicles were pinched off externally from the surface of the macrogamete. There appeared to be 2 forms of wall-forming bodies of the Type I during development, one form being less osmiophilic than the other. Other organelles present, such as wall-forming bodies of Type II, granular endoplasmic reticulum, mitochondria, canaliculi, lipid inclusions and intravacuolar folds, were similar in structure to those of other Eimeria species.
Isoenzyme characterization of trypanosomes of the subgenusHerpetosoma
Authors: Mohamed H. A. , Molyneux D. H. , Scott C. M. 
Published: June 2009

SUMMARYIsoenzyme analysis was used to characterize 6 species of trypanosomes of the subgenusHerpetosomausing 13 different enzyme systems. The species studied wereTrypanosoma lewisi, T. musculi, T. grosi, T. microti, T. evotomysandT. nabiasiwhich cannot be distinguished on morphological grounds. Extracts for thin-layer starch-gel electrophoresis were prepared from cultures of insect forms in either Schneider'sDrosophilaor Grace's insect tissue culture media with foetal calf serum or a nutrient agar medium. Extracts ofT. lewisiandT. musculibloodstream forms were also run for comparison. All parasites gave distinct patterns which enabled them to be differentiated on one or more enzyme systems. Two types of computer analysis were used to group the parasites; using these techniques the murine parasitesT. lewisi, T. musculiandT. grosifell into one broad group, andT. microtiandT. evotomysof microtine rodents formed another. These findings are in accord with earlier observations on the behavioural characteristics of these parasites in their mammalian host and their vector (fleas). The clear differences observed provide the basis for the application of other biochemical and immunological techniques for differentiation within this subgenus of trypanosomes.
Fasciola hepatica: attempts to induce protection against infection in rats and mice by injection of excretory/secretory products of immature worms
Authors: Rajasekariah G. R. , Mitchell G. F. , Chapman C. B. , Montague P. E. 
Published: June 2009

SUMMARYIn vitroexcretory/secretory products of 4-week (immature) and 8- week-old (mature)Fasciola hepaticaparasites, derived from rats, were injected together with adjuvant into naive rats and mice. Resistance to infection was assessed in rats by counting adults in the bile ducts at 9 weeks, or in mice by recording deaths after oral challenge with a high dose of viable metacercariae. Exposure of rats to excretory/secretory products of immatureF. hepaticaconferred a significant degree of resistance which was comparable to the level of resistance induced following oral administration of a low number of metacercariae. No protection against infection was seen in rats injected with excretory/secretory products from mature, bile duct-derived worms. In mice, no obvious mouse strain variation in susceptibility to first infection existed and hypothymic nude mice were as susceptible to infection as intact mice. As determined by protection against death, vaccination with excretory/secretory products derived from immatureP. hepaticawas without effect in mice. It is concluded that ‘host protective antigens’, at least for rats, were present in the excretory/secretory products of immatureF. hepaticalarvae.
Helminth parasites of Jamaican anoles (Reptilia: Iguanidae): variation in prevalence and intensity with host age and sex in a population of Anolis lineatopus
Authors: Vogel P. , Bundy D. A. P. 
Published: June 2009

SUMMARYThe Jamaican iguanid lizard Anolis lineatopus is the host of 4 species of helminth parasite: an acanthocephalan (Centrorhynchus spinosus), a digenean (Mesocoelium danforthi), and 2 nematodes (Cyrtosumum scelopori and Thelandros (?cubensis). Prevalance of C. spinosus was unrelated to host age but was considerably higher in males (43%) than in females (10%). The intensity increased with host age: (range: 1–23, median: 3). Prevalence of C. scelopori increased with host age in both sexes: juveniles (<3 months) were uninfected while infection occurred in almost all lizards older than 9 months. Intensity was higher in males (range: 1–403, median: 158) than in females (range: 1–297, median: 86). The infection patterns of C. spinosus and C. scelopori differed significantly from each other and were not consistent with a simplistic direct relationship between time of exposure and infection prevalence. Acanthocephalan and digenean infections occurred at low prevalence and intensity although prevalence in older, larger lizards tended to be higher than in younger, smaller ones.
Cytochemical studies on nuclear DNA of four eucoccidian parasites,Isospora (Toxoplasma) gondii, Eimeria tenella, Sarcocystis cruziandPlasmodium berghei
Authors: Cornelissen A. W. C. A. , Overdulve J. P. , Ploeg M. Van Der 
Published: June 2009

SUMMARYFeulgen-pararosaniline(SO2) staining was performed on stages in the life-cycle ofIsospora (Toxoplasma) gondii, Eimeria tenella, Sarcocystis cruziandPlasmodium berghei. The fluorescence emission of the stained DNA in nuclei of these stages was examined and compared with absorption microscopy measurements at 560 nm (green light) of the same specimens. Accurate identification of single cells, and especially discrimination between young schizonts and young gamonts was difficult after Feulgen staining. To overcome this problem preparations were first stained with Giemsa and the cells of interest precisely located with the aid of an England finder. The same preparations were then hydrolysed and stained with Feulgen—pararosaniline(SO2), after which the previously identified cells were investigated. The DNA distribution after Feulgen staining corresponded with the shape of nuclei after Giemsa staining. DNA was present in all investigated stages of the four parasites, including macrogamonts ofI. (T.) gondiiandE. tenellaand peripheral blood gamonts ofP. berghei. Macrogamonts could be recognized, even at a stage at which they can hardly be differentiated from young schizonts in Giemsa-stained preparations, by their typical distribution pattern of Feulgen fluorescence. Feulgen fluorescence was more granular and confined to the peripheral region of the nucleus, leaving a distinct nucleolus unstained. The horseshoe-shaped nuclei typical of macrogamonts could also be observed in some second generation merozoites ofE. tenella, indicating that these merozoites are already sexually differentiated. The relationship between the present cytochemical observations and the ultrastructure of the four investigated parasites is discussed.
The anaerobic end-products of helminths
Authors: Barrett J. 
Published: June 2009

Parasitic helminths belong to 3 separate phyla and there is always the danger of over-generalization. The various routes of anaerobic carbohydrate breakdown in parasitic helminth differ in their efficiencies and in their power output. The choice of end-product represents a compromise between these two conflicting forces. In addition, anaerobic pathways must satisfy the redox requirements of the tissues and provide a source of intermediates for synthetic reactions. Other considerations include the metabolic cost of excretion and the effect of end-products on protein structure and function. The different end-products may fulfil additional functions such as pH control, nitrogenous excretion, osmotic regulation, intracellular signalling and the suppression of host responses.A complicating factor in parasitic helminths is the existence of strains with different biochemical characteristics, including marked variation in end-product formation. The various tissues of the same parasite can also produce different end-products and the pattern of end-product formation is influenced by a variety of extrinsic and intrinsic factors such as age, sex, length of incubation, pO2 and availability of substrates. The catabolic pathways of helminths thus show considerable functional adaptation.There is, as yet, no satisfactory explanation as to why helminths do not make the maximum use of any oxygen available to them; and the contribution of oxidative processes to the overall energy balance of parasites probably varies from species to species.The catabolic pathways of adult helminths are derived from the anaerobic pathways present in their free-living relatives. Two main trends are evident, homolactic fermentation and carbon dioxide fixation, the latter involving a partial reverse tricarboxylic acid cycle. In general, homolactic fermentation is found in blood and tissue parasites, carbon dioxide fixation in gut parasites. These two types of metabolism are, of course, in no way absolute, most homolactic fermentors fix carbon dioxide to a certain extent and many parasites which fix carbon dioxide also produce lactate. Parasitic helminths possess a wide range of different catabolic pathways, superimposed upon which is a high degree of functional plasticity.
Density-dependent mechanisms in the regulation ofFasciola hepaticapopulations in sheep
Authors: Smith Gary 
Published: June 2009

SUMMARYPopulations ofFasciola hepaticainfecting sheep are regulated by at least 3 density-dependent processes. Parasite deaths due to parasite-induced primary host mortality, fluke fecundity and asexual multiplication in the intermediate snail host,Lymnaea truncatula, vary according to the intensity of infection. Empirical and theoretical evidence is used to assess theextentto which each of these processes in turn affects parasite population numbers.
Schistosoma mansoni: DNA synthesis in males and females from mixed and single-sex infections
Authors: Den Hollander J. E. , Erasmus D. A. 
Published: June 2009

SUMMARYThe pattern of DNA synthesis in male and femaleSchistosoma mansonifrom mixed and single-sex infections in mice has been determined biochemically and autoradiographically using the incorporation of [3H]-thymidine as a specific marker of DNA synthesis. During early development (up to 35 days post-infection (p.i.)) adult males and females from mixed infections had a comparable specific activity of DNA. In males, from 35 days p.i. onwards, the specific activity of DNA decreased rapidly to become significantly different from that observed in females. In single-sex infections DNA synthesis in females was depressed compared to that observed in males from single-sex infections and was also significantly different (P≼ 0·01) from DNA synthesis in females from mixed infections. There was no significant difference in DNA synthesis between males from single or mixed infections. DNA synthesis in both sexes was found to be sensitive to hydroxyurea treatment, the inhibition in sexually mature females being approximately 75% and in males approximately 45%. Autoradiography using both light microscope and electron microscope techniques revealed that the testes and ovary had labelled cells. In male schistosomes the only other labelled cells were small undifferentiated cells found scattered through the tissues. In females the vitelline gland had large numbers of densely labelled nuclei within Stage 1 vitelline cells, as well as numerous small undifferentiated cells.
Schistosoma mansoni: further studies of the interaction between schistosomula and granulocyte-derived cationic proteinsin vitro
Authors: McLaren Diane J. , Peterson C. G. B. , Venge Per 
Published: June 2009

SUMMARYPurified eosinophil and neutrophil cationic proteins isolated from the lysosomal secretion granules of human leucocytes have been tested for cytotoxic capacity against lung-stage schistosomula ofSchistosoma mansoni in vitro. Eosinophil cationic protein (ECP) caused paralysis but not death at high concentration; this effect was reversible and involved no gross pathological manifestations. Eosinophil protein X (EPX) and neutrophil cationic protein (NCP) were highly toxic at concentrations of 10−5mol/1, and induced paralysis at sublethal concentrations. These two proteins exerted their cidal effect principally against the subtegumental musculature and internal tissues of the parasite rather than against the surface syncytium and tegumental outer membrane. ECP and NCP were shown to bind to lung worms at paralysing concentrations, but this binding occurred independently of the charge of the parasite surface. Of several control proteins tested, only protamine was capable of destroying lung-stage parasites; the manifestations of damage were different, however, from those induced by the granulocyte-derived proteins. Parallel assays demonstrated that EPX also possessed cytotoxic capacity against newly transformed schistosomula, but it was less efficient than ECP in this respect. The data are discussed in relation to potential post-skin mechanisms of challenge attrition in the immunized host.