bluuebunny/crossref_metadata_2025 huggingface dataset:
Dipetalonema viteae in hamsters: effect of antiserum or immunization with parasite extracts on production of microfilariae
Authors: Haque A. , Lefebvre M. N. , Ogilvie B. M. , Capron A.
Published: June 2009

After hamsters have been infected with Dipetalonema viteae for about 4 months, microfilariae disappear from the circulation but the adult worms remain alive and active. Such hamsters are said to harbour a ‘latent’ infection. Additional adult worms implanted into such hamsters produce no microfilariae, but adult worms recovered from hamsters with latent infections resume microfilariae production when surgically transplanted into new hosts. In vitro, worms from hamsters with latent infections renewed microfilariae production in the presence of serum from uninfected but not infected hamsters. Serum from infected animals had a marked suppressive effect on the microfilariae production of adult worms implanted into passively immunized hamsters. This suggests that microfilarial release is regulated by a serum factor. Microfilarial production in in vitro and in vivo experiments was more strongly inhibited by serum taken from hamsters with latent infections and hamsters infected for only 30 days (pre-patent) than by serum taken 90 days after infection (whilst microfilariae were in the circulation of the serum donors). A cytotoxic effect of sera from infected hamsters on the microfilariae could not be demonstrated.

In animals immunized by extracts of adult worms or microfilariae, microfilaraemia was considerably reduced. In contrast, animals immunized repeatedly with the extract from small numbers of microfilariae during the pre-patent phase of an infection had an enhanced microfilaraemia. Adult worm numbers were not affected by immunization except in animals given extract from a single female worm which harboured fewer worms than controls.
The effect of variations in host and parasite density on the level of parasitization of Lymnaea truncatula by Fasciola hepatica
Authors: Wilson R. A. , Taylor Susan L.
Published: June 2009

Groups of the snail Lymnaea truncatula, maintained at a range of spatial densities, were exposed to different densities of miracidia of Fasciola hepatica. The resulting degree of parasitization was measured 3–4 weeks after infection. The relationship between parasite densities and parasitization appeared to be curvilinear. The lower than expected parasitization at high parasite densities could be explained by the multiple infection of some snails by two or more miracidia.

The level of parasitization was not related exponentially to the temperature at which infection was carried out. This was thought to be due to the inverse relationship between miracidial longevity and swimming speed, with respect to temperature. A depth of free water overlying a mud surface was an absolute requirement for miracidia to successfully infect snails.
Studies on the transmission and course of infection of a Kenyan strain of Theileria mutans
Authors: Young A. S. , Purnell R. E. , Payne R. C. , Brown C. G. D. , Kanhai G. K.
Published: June 2009

Theileria mutans (Aitong) isolated from cattle exposed in the Narok District of Kenya and blood-passaged through cattle 8 times, appeared to have lost its original pathogenicity for cattle. It was demonstrated that the parasite was trans-stadially transmissible by the tick Amblyomma variegatum but not by Rhipicephalus appendiculatus. Four tick–bovine passages were made using A. variegatum, and infective parasites were also harvested from A. variegatum nymphs which had been fed for 5 days on rabbits. Blood containing piroplasms, or lymphoid cells infected with schizonts taken from cattle, at the 2nd tick–bovine passage were shown to be infective on inoculation.

The course of the T. mutans infections in the cattle was studied. In tick-induced infections macroschizonts occurred transiently, persisting longest in circulating lymphoid cells. Microschizonts were rarely detected. The macroschizonts were morphologically distinct from those of other Theileria species described from East Africa.

In tick-induced infections, the piroplasm parasitaemia increased rapidly and there was evidence of restored pathogenicity of the parasite since high piroplasm parasitaemias were associated with a marked anaemia.
Schistosoma mansoni: a comparative study of artificially transformed schistosomula and schistomula recoverd after cercarial penetration of isolated skin
Authors: Brink Linda H. , McLaren Diane J. , Smithers S. R.
Published: June 2009

A comparison was made of the ultrastructure, development and antigenic nature of the surfaces and of the viability of three types of schistosomula ofSchistosoma mansoni: schistosomula formed afrer cercariae had penetrated isolated skin (SS), schistosomula produced after mechanical separation of cercarial tails from bodies (MS), and schistosomula transformed from cercariae after incubation in fresh rat serum (RS).

Within 2 h of transformation, the surface membrane of all three types of schistosomula had changed from trilaminate to heptalaminate structures and SS and MS had lost their cercarial glycocalyx. Initially a dense amorphous material was demonstrated on the surfaces of RS, which was thought to be the result of an interaction between a factor in rat serum and the glycocalyx: this material was greatly reduced within 2 h of transformation. The pre-acetabular glands of SS were emptied while those of MS and RS retained their contents. Immunofluorescent studies showed that all schistosomula bound serum from mice immune toS. mansoni, but the binding was stronger with MS and RS. The mixed agglutination reaction demonstrated the presence of human A and B blood group-like antigenic determinants on approximately 30% of 3 h old SS; these determinants were not detected on MS or RS.In vitro, the development of MS and RS was similar to SS; the first schistosomula reached the ‘gut-closed’ stage by day 10; 50–70% of SS reached this stage by day 12, in contrast to only 25–50% of MS and RS. Between 28 and 45% of all schistosomula developed to maturity when injected intravenously into mice.

It was concluded that the two types of artificially prepared schistosomula fultil the main criteria of transformation from cercaria to schistosomulum. Further, it is suggested that MS are the most appropriate source of material for immunochemical and physiological studies.
The longevity of Hymeonlepis microstoma in mice, and its immunological cross-reaction with Hymenolepis diminuta
Authors: Hopkins C. A. , Goodall R. I. , Zajac A.
Published: June 2009

Hymenolepis microstoma was found to live for at least 728 days in a mouse, but an initial infection of 10 worms per mosue decreased exponentially for approximately the first 110 days to a level of 3–5 worms, after which little further loss occurred.

A primary infection of six H. microstoma, expelled with anthelmintic on day 21, strongly protected against a single worm H. diminuta challenge; worms in 80 ‘immunized’ mice weighed less than 5% of the weight of worms from 80 control mice. However, a primary (5-worm) H. diminuta infection led only to a small, though statistically significant, decrease in weight of the 3-worm H. microstoma challenge.

The results are interpreted as indicating that H. microstoma evokes a strong immunological response which cross-reacts with H. diminuta. The failure of H. diminutato protect strongly against a 3-worm challenge by H. microstoma suggests, as does the long survival of a primary infection when it is reduced to approximately 4 worms, that H. microstoma survives in low infection because it is able to avoid the immune response. This could be due to antigen camounflage, ability to repair immune damage or to the low permeability of the bile duct wall to components of the immune response. The worm loss which occurs from heavy infection until only 3–5 worms remain may be physiologically rather than immunologiacally mediated.
Further observations on the genetic transfer of drug resistance in Eimeria maxima
Authors: Joyner L. P. , Norton C. C.
Published: June 2009

Experiments are described which support the view that, in Eimeria maxima, drug resistance factors are transferred at zygote formation. The phenomenon occurred between infections which were initiated by the inoculation of merozoites. It also took place between variants of the same, but not between different species. Transference of drug resistance wsa not affected by the treatment of the chicks with acriflavine.
Pholeter anterouterus Fischthal & Nasir, 1974 (Digenea: Opisthorchiidae) redescribed, together with remarks on the genera Pholeter Odhner, 1914 and Phocitrema Goto & Ozaki, 1930 and their relationship to the centrocestine heterophyids
Authors: Pearson J. C. , Courtney C. H.
Published: June 2009

Photoleter anterouterus Fischthal & Nasir, 1974, from Pelecanus occidentalis Linnaeus and Pelecanus erythrorhynchos Gmelin from Florida, USA and the ventrogenital complexes of Photoleter gastrophilus (Kossack, 1910) from Delphinus delphis Linnaeus from Queensland, Australia and of Phocitrema fusiforme Goto & Ozaki, 1930 from Alopex lagopus (Linnaeus) and Phoca vitulina Linnaeus from Alaska are redescribed. The genus Photoleter Odhner, 1914 is emended and compared with Phocitrema Goto & Ozaki, 1930 and both genera are compared with members of, and as a result transferred from the family Opisthorchiidae Looss, 1899 to, the subfamily Centrocestinae Looss, 1899, family Heterophyidae Odhner, 1914.
Early developmental changes of the schistosomula ofSchistosoma mansoni in vitroand in mouse lung
Authors: Imohiosen E. A. E. , Sher Alan , Lichtenberg F. Von
Published: June 2009

Fresh (3 h) schistosomula ofSchistosoma mansoniwere obtained by the skin penetration method and injected intravenously into groups of mice either immediately or after 48 h incubation in tissue culture. Schistosomula were then recovered from the lungs 1 to 2 days after injection. The recovery results showed that the ability of uncultured schistosomula to emerge from lung tissue increased with time, became maximal on the 3rd day and diminished thereafter. In contrast, cultured schistosomula were able to emerge from chopped lung at a much earlier time after injection.

Fresh schistosomula, as well as those recovered from mouse lungs, were assayed by indirect immunofluorescence for the presence of parasite and host antigens. Similarly, fresh schistosomula which had been incubated in foetal calf serum, with or without mouse red blood cells, were assayed for parasite and host antigens after 3–24 h of culture. Fresh schistosomula expressed parasite antigen with greater intensity than those recovered from mouse lungs and showed no trace of host antigen. Lung schistosomula, on the other hand, expressed less parasite antigen but more red blood cell antigen with increasing time in the host. Schistosomula cultured in the absence of mouse red blood cells expressed only parasite antigen throughout the period in culture, while those cultured in the presence of mouse red blood cells also expressed parasite antigen during the entire period in culture but, in addition, by 24 h host antigen could also be detected.

These developmental and adaptational changes may play a role in determining the survival of parasites in the normal or immune host.
Immunity to primary and challenge infections of Trichinella spiralis in mice: a re-examination of conventional parameters
Authors: Wakelin D. , Lloyd M.
Published: June 2009

In young (6- to 8-week-old) NTH strain inbred mice expulsion of a primary infection of Trichinella spiralis began on day 8 and was virtually complete by day 11·5. In older mice expulsion occurred 1 or 2 days earlier. Experience of a primary infection elicited strong immunity to challenge, whether the challenge was given immediately after worm expulsion (day 14) or delayed (day 42). Challenge infections were expelled rapidly, the majority of worms being lost during the first day. Immunity to challenge was elicited by low-level primary infections and was effective against large challenge infections. These results are discussed in relation to conventionally accepted parameters of immunity to T. spiralis in mice which, it is considered, are applicable only to mice with a genetically-determined low-level of responsiveness to the parasite.
Corynebacterium parvumas an adjuvant forTrypanosoma cruziepimastigote vaccines: a comparison with saponin andBordetella pertussis
Authors: Bomford R. , McHardy N.
Published: June 2009

The effect was compared in CBA mice of addingCorynebacterium parvum, saponin, andBordetella pertussisto living or killedTrypanosoma cruzi(Y strain) epimastigote vaccines on the induction of protective immunity against subcutaneous (s.c.) challenge with blood trypomastigotes. The addition ofC. parvumto a low dose ofT. cruzivaccine, which alone was non-protective, generated a greater degree of protection than did saponin orB. pertussis. C. parvumalone increased resistance to infection to a variable and usually weak extent. The addition ofC. parvumto larger doses ofT. cruzivaccine, which were themselves sufficient to elicit some degree of protection, improved resistance when the challenge was given 1 or 12 weeks after immunization, but lowered it at 3 weeks. It is concluded that the comparative efficacy of adjuvants forT. cruzivaccines needs to be assessed on 3 parameters: (1) the dose of antigen, (2) the dose of adjuvant and (3) the time interval between immunization and challenge.
Patterns of milk transmission of Strongyloides ratti
Authors: Wilson P. A. G. , Cameron Maureen , Scott D. S.
Published: June 2009

Eight days after mother rats were injected with 4000 infective larvae of Strongyloides ratti at different stages of lactation the numbers of adult worms in their intestines were uniformly low (< 3% of the dose) compared with unmated controls (mean = 25%). Those in their litters varied from 12% on day 5 to a maximum of 47% on day 17 post partum. These data, which do not correlate with lactational performance, imply that parasite movements in lactating rats are controlled by qualitative, not quantitative, consequences of humoral events. The numbers of worms in litters are concluded to be the result of the interaction of dynamic determinants of larval routes in the mother and changes in the suitability of the neonatal gut as an environment for worm development. The timing of events leading to milk-borne infection is defined. Injected larvae were closely synchronized in their movements, which were completed in 36 h. Larvae experimentally diverted into the mother's tissues during her first lactation were not available for the infection of a second litter.
Genetic studies on Plasmodium chabaudi: recombination between enzyme markers
Authors: Walliker D. , Carter R. , Sanderson A.
Published: June 2009

Two lines of Plasmodium chabaudi differing in three characters have been crossed, using a technique previously described for P. yoelii. One line, termed 47AS, was characterized by an electrophoretic form of 6-phosphogluconate dehydrogenase, denoted 6PGD-2, a form of lactate dehydrogenase, denoted LDH-3, and was pyrimethamine-resistant. The second line, termed 10AJ, possessed enzyme forms 6PGD-3 and LDH-2 and was pyrimethamine-sensitive. The cross was made by permitting mosquitoes to feed on a mixture of the two lines and infecting rodents with the resulting sporozoites. The products of the cross were cloned by dilution and examined for enzyme-type and drug-response. Results showed that recombination had occurred between each of the three characters. Clones characterized by 6PGD-2/LDH-2 and 6PGD-3/LDH-3 demonstrated recombination between the enzyme markers. The drug-resistance character segregated independently of either enzyme marker.
The identity ofLeishmania tarentolaeWenyon 1921
Authors: Wallbanks K. R. , Maazoun R. , Canning E. U. , Rioux J. A.
Published: June 2009

A double clone ofTrypanosoma platydactyliCatouillard, 1909, derived from a single trypomastigote from the blood of the Moorish gecko,Tarentola mauritanica, was grownin vitro. Morphogenesis of the parasites led to a stable population of promastigotes which were identical, in general morphology, ultrastructure and the electrophoretic mobility of 8 enzymes, to those cultures previously considered to beLeishmania tarentolaeWenyon, 1921. These cultures included the strain isolated from the type locality in Algeria by Parrot (1949) and later used as a laboratory model for the genusLeishmania. T. platydactyliandL. tarenlolaeare synonymized and the present status of saurianLeishmaniaparasites is discussed.
Cytochemical localization of cytochrome oxidase in tissues of parasitic nematodes
Authors: Fry M. , Beesley J. E.
Published: June 2009

Cytochemical staining with diaminobenzidine (DAB) has been used to locate cytochrome oxidase activity in mitochondria from major tissues of three intestinal parasitic nematodes, Nippostrongylus brasiliensis, Haemonchus contortus and Ascaridia galli. Deposition of DAB reaction product was uniform and relatively intense in mitochondria from all tissues studied in N. brasiliensis. However, mitochondria from different tissues of H. contortus and A. galli varied considerably in their cytochemical staining, decreasing in the order hypodermis < muscle < gut < reproductive tissue. Mitochondria in gut and reproductive tissue of A. galli possessed little or no cytochrome oxidase activity. These results are compatible with respect to oxygen availability and the extent and localization of the mammalian-type aerobic mitochondrial electron transport pathway in intestinal parasitic nematodes.
Population dynamics of snail infection by miracidia
Authors: Anderson R. M.
Published: June 2009

The essential biological features of snail infection by miracidia are incorporated into a simple model which describes the rate of change with respect to time of the number of miracidial infections/host. The model is based on the assumption that the net rate of infection is directly proportional to the density of both miracidia and hosts. Empirical evidence is provided to support this assumption. The basic framework of the model is expanded to take into account demographic stochasticity in infection and is used to predict the percentage of snails that become infected after exposure to a known number of miracidia for a set period of time. The influence of miracidial mortalities and age-dependent infectivity are examined and theoretical predictions are compared with a range of experimental results.

Underlying heterogeneity in the distribution of the number of infections/snail is shown to generate an artifactual decrease in infection rates as exposure density rises, if rate estimation procedures are based on an assumption of randomness. Empirical evidence is presented to illustrate the generation of over-dispersion in the number of miracidial infections/snail under tightly controlled laboratory conditions, using supposedly homogeneous snail populations.

Biological causes for underlying patterns of heterogeneity are discussed in relation to snail susceptibility to infection and ‘attractiveness’ to infective stages.
The cestocidal effect of complement in normal and immune sera in vitro
Authors: Herd E. P.
Published: June 2009

The effects of complement and/or specific antibodies on the larval and adult stages of Echinococcus granulosus were studied in vitro. Lysis and death of both protoscoleces and adult E. granulosus occurred within 10 min to 24 h in 50% fresh normal sera used as a source of complement, without the presence of specific antibodies. The lytic and lethal reaction was marked in fresh sera from guinea-pigs, calves, dogs, man and sheep, but only slight in fresh sera from English rabbits and horses. Guinea-pig sera were shown to be complement deficient after reacting with worms and all reactions were abolished after sera had been heated to 56 °C for 30 min. Fluorescent antibody studies failed to detect host antibodies at the parasite tegument. It is suggested that activation of the complement system occurs via the alternate pathway, that it acts independently of the immune system and that it is lethal to a wide range of cestode parasites.

In contrast, marked agglutination/precipitation reactions with protoscoleces and precipitation reactions with adult E. granulosus were observed after incubation in heat inactivated 50% canine antisera, but not in normal sera. The antigen-antibody nature of these reactions was established by fluorescent antibody studies and the areas of antibody attack pinpointed. In spite of these reactions, worms remained healthy and active over a period of 8 days.
Intestinal pathology associated with Trichostrongylus colubriformis infection in sheep: vascular permeability and ultrastructure of the mucosa
Authors: Barker I. K.
Published: June 2009

Increased permeability of capillaries and venules, labelled with colloidal carbon, was observed in the superficial mucosa of the small intestine of sheep infected with Trichostrongylus colubriformis. The labelled vessels were restricted to infected portions of the gut, and the intensity of labelling appeared to be related to density of the worm population. Open junctions were seen between endothelial cells in permeable vessels. In moderately atrophic infected intestine, enterocytes were domed, had sparse, short, distorted microvilli and many polyribosomes. Tight junctions between enterocytes seemed to be intact and distended intercellular spaces were seen. In more severely atrophic mucosa, enterocytes had distended mitochondria and endoplasmic reticulum, bizarre shapes, and the continuity of the epithelial sheet was occasionally disrupted. There was oedema in the lamina propria and neutrophils were seen in migration to the lumen of the gut. The possible mechanisms inducing these changes and their significance in terms of plasma protein loss and intestinal function are discussed.
Separation of Isospora (Toxoplasma) gondii cysts and cystozoites from mouse brain tissue by continuous density - gradient centrifugation
Authors: Cornelissen A. W. C. A. , Overdulve J. P. , Hoenderboom J. M.
Published: June 2009

A simple, quick and reproducible method consisting of density-gradient centrifugation of homogenized infected mouse brain tissue on Percoll is described for the isolation and purification of cysts of Isospora (Toxoplasma) gondii. A 100% recovery of cysts, with 74·2% in a single fraction with a specific gravity of 1·056, was obtained by overlaying homogenates of infected mouse brains on a pre-formed Percoll gradient and centrifugation at low g forces. With this procedure recovery was independent of the age of the cysts. Titration of purified cystozoites showed there to be no loss of infectivity.
Isolation and partial characterization of the tegumental outer membrane of adultSchistosoma mansoni
Authors: Simpson A. J. G. , Schryer M. D. , Cesari I. M. , Evans W. H. , Smithers S. R.
Published: June 2009

Incubation of adultSchistosoma mansoniat 37 °C in chemically defined media caused the shedding of variable amounts of the parasite's tegument. In phosphate-buffered saline, pH 7·4, 37% of125I-labelled wheat germ agglutinin which was attached to the schistosome surface was released within 5 min. When the released material was collected by centrifugation at 55000gfor 1 h, the pellet was seen to consist of components of the parasite tegument and contained 1% of the parasite protein and 6·2% of the 5′-AMPase activity. By monitoring the release of the gut enzyme, haemoglobinase, it was shown that predominantly tegumental material was released under these conditions. The material released from the parasite was separated by discontinuous sucrose gradient centrifugation into 4 major fractions and it was shown that a material banding at low density was highly enriched in vesicles of parasite outer membrane. Major polypeptides of apparent molecular weights 135000, 110000, 90000, 65000, 47000 and 40000 and glycoproteins of apparent molecular weights 135000, 120000, 65000, 63000 and 30–40000 were identified in this fraction. Comparison of the distribution of 5′-AMPase activity and the contents of each fraction as revealed by ultrastructural examination showed that this enzyme is a good marker for the tegumental outer membrane.
The ribosomes of Plasmodium berghei: isolation and ribosomal ribonucleic acid analysis
Authors: Miller F. W. , Ilan Judith
Published: June 2009

Ribosomes and high molecular weight ribosomal ribonucleic acid (rRNA) from the blood stages of Plasmodium berghei parasites were studied in preparations free from host ribosome contamination. Purified malarial ribosomes were isolated in high yield from a population of ultrastructurally intact, viable parasites by hypertonic lysis with Triton X-100 and differential centrifugation. These ribosomes were shown to be derived from active polysomes and could be dissociated into subunits by puromycin–0·5 m KCl treatment. Malarial rRNA extracted from purified 40S and 60S ribosomal subunits was characterized by electrophoretic, sedimentation and base ratio analyses. Like certain other protozoa, the P. berghei 40S ribosomal subunit possessed an exceptionally large RNA species (mol. wt 0·9 × 106), while RNA isolated from the parasite's 60S subunit (mol. wt 1·5 × 106) was specifically ‘nicked’ to produce one large component (mol.wt 1·2 × 106) and one small component (mol.wt 0·3 × 106) in equimolar quantities. These rRNA's migrate identically on polyacrylamide gels after heating to 63°C for 5 mm or under denaturing conditions in the presence of formamide, indicating an absence of aggregation and non-specific degradation of the rRNA species. Base composition studies showed P. berghei rRNA to be low in guanosine and cytosine content, as is the case for protozoa generally.
Invasion of vertebrate lungs by the polystomatid monogeneans Pseudodiplorchis americanus and Neodiplorchis scaphiopodis
Authors: Tinsley R. C. , Earle Celia M.
Published: June 2009

Some unique features of monogenean biology have emerged from studies on 2 polystomatids which infect spadefoot toads in Arizona, USA: Pseudodiplorchis americanus in Scaphiopus couchii and Neodiplorchis scaphiopodis in S. multiplicatus and S. bombifrons. Transmission is confined to 1–3 nights each summer when the desert-adapted toads enter water to spawn. Encapsulated larvae complete development in utero and hatch within seconds of deposition; their body length (up to 600 μm) is 2–4 times greater than that of most other oncomiracidia, and their swimming life (over 48 h at 25–27 °C) is twice that usual amongst monogeneans. The ciliated oncomiracidia invade the nostrils, a target usually above the water surface and requiring migration over the exposed skin; remarkably they tolerate drying for up to 1 h (at 32 °C, 45% rel. hum.). The larvae migrate via the buccal cavity and glottis to the lungs where juvenile development occurs until early autumn. Migration from the lungs to the urinary bladder (by an as yet undetermined route) is followed by maturation and reproduction during host hibernation, and developing embryos accumulate in preparation for a period of transmission more restricted than that of any other monogenean. No other monogenean is known to exploit the lungs nor to inhabit, successively, anterior and posterior sites of the same adult host individual.
The production and functional morphology of helminth egg-shells
Authors: Wharton D.A.
Published: June 2009

The high energy costs of egg-shell production in many helminths suggests that this structure plays an important role in their biology. The mechanical and chemical resistance of the egg-shell and the barrier it provides to the entry and loss of material are important in the survival of the free-living stages within the egg. The presence of egg filaments may increase the availability of infective stages and the operculum may be important in the infective process.
Fallisia (Plasmodioides) neotropicalissubgen. nov. sp.nov. from Venezuela
Authors: Gabaldon A. , Ulloa G. , Zerpa N.
Published: June 2009

A new subgenus and species of avian haemocytozoonFallisia (Plasmodioides) neotropicalisis described. The principal characteristics are the main host cells, thrombocytes and mononuclear leucocytes, where trophozoites, schizonts and gametocytes are found. Occasionally, granulocytes and very rarely reticulocytes are also parasitized. Phanerozoites very similar to those ofPlasmodiumof birds are also present. The host is the domestic pigeon,Columbalivia, an imported species but similar parasites have been identified, always mixed with species ofPlasmodium, in several indigenous species of Ciconiiformes, which seem to be the natural hosts. This is the first report in birds of a representative of the genusFallisia, parasites of neotropical lizards.
Plasmodium berghei-infected red cells sorted according to DNA content
Authors: Howard R. J. , Battye F. L.
Published: June 2009

A cell-sorting method is described for the analysis and separation of red blood cells in Plasmodium berghei-infected mouse blood based on their DNA content. This method involves a selective uptake of the bis-benzimidazole dye 33258 Hoechst, a DNA-binding dye, by red blood cells containing parasites. Infected blood is incubated at 37 °C with the dye then washed at 4 °C to remove unbound dye. Uninfected cells are then non-fluorescent at the characteristic wavelengths for 33258 Hoechst excitation and emission, whereas parasitized cells display fluorescence intensities in approximately direct proportion to the number of parasite nuclei (i.e. amount of parasite DNA) within the cell and can be sorted accordingly. Providing cells were incubated in a complex nutrient medium during dye uptake at 37°C, the sorted parasite cells produced lethal P. berghei infections when injected into BALB/c mice. The dyelabelling technique is simple and sufficient red blood cells at various stages of infection can be collected for biochemical or immunochemical studies by cell sorting.
Kinetics of mast cell, basophil and eosinophil populations atHyalomma anatolicum anatolicumfeeding sites on cattle and the acquisition of resistance
Authors: Gill Harsharnjit S.
Published: June 2009

The cutaneous cellular reactions associated with aquisition of resistance by cattle toHyalomma anatolicum anatolicumfeeding were investigated by comparing the nature and sequence of cellular events atH.a. anatolicumfeeding sites following primary and tertiary infestations. Cattle acquired resistance toH.a. anatolicumfeedings after a single infestation. The resistance was manifested by a significant reduction in the mean weight of engorged females and mean weight of egg mass produced, failure to lay eggs and sometimes death of ticksin situ. The acquisition of resistance corresponded with pronounced epidermal vesiculation and a significant change in the nature of the cellular infiltrate at tick feeding sites indicating the development of cutaneous hypersensitivity. On primary infestation the cellular infiltrate was dominated by neutrophils (43–71%) followed by mononuclear cells (25–35%). Basophil and eosinophil infiltration in small numbers was noticed for the first time at 72 and 144 h, respectively, post-primary infestation. Unlike primary infestation, the dermal infiltrate on tertiary infestation, 24 h after attachment, was characterized by infiltration of basophils (6%) and eosinophils (3%) and a marked degranulation of mast cells and basophils. Basophils showed a consistent increase in absolute as well as relative numbers as the feeding advanced. They were the second most abundant cell types after neutrophils (48–68%) at 72 h (16%), and 144 h (23%). Eosinophils (3–9%) and mononuclear cells also showed a significant increase in their mean numbers as compared with primary infestation. There was a progressive decrease in the number of detectable mast cells following tick infestation and they were significantly lower post-tertiary infestation, compared to primary infestation. These results suggest that the pharmacological mediators released by degranulation of mast cells and basophils are perhaps the major effectors of resistance in cattle toH.a. anatolicum.
A scanning electron microscope study of the male copulatory sclerite of the monogenean Diplectanum aequans
Authors: Maillard C. , Gonzalez J. , Noisy D.
Published: June 2009

The cirrus of a monogenean Diplectanum aequans was isolated by treatment with sodium carbonate solution and studied with a scanning electron microscope. The method may be used in studies of the functional morphology and taxonomy of other organisms.
Copepod parasites of deep-sea fish off the Galápagos Islands
Authors: Ho Ju-Shey
Published: June 2009

Five species of parasitic copepods are described based on the material collected during cruise 16 of R/V Anton Bruun. They are: from the gill chambers of macrourids, Chondracanthodes deflexus Wilson, Lateracanthus quadripedis Kabata and Gusev and Brachiella annulata Markevitch; from the anal fin of a macrourid, Nudiclavella galapagoense gen.nov., sp.nov.; and from the gill filaments of brotulids, Naobranchia maxima sp.nov. All fishes were caught with FVSL (free vehicle set lines) in the deep sea off the Galápagos Islands, ranging from 1710 to 3330 m.
A comparative study of susceptibility of inbred and outbred mouse strains compared with hamsters to infection with New World cutaneous leishmaniases
Authors: Neal R. A. , Hale C.
Published: June 2009

One stock of each of Leishmania mexicana mexicana and L. m. amazonesis together with two stocks of L. braziliensis panamensis and L. b. braziliensis were tested for infectivity in inbred mouse strains Balb/c and CBA/H. The infectivity was compared with hamsters and the outbred CD1 mice. Balb/c mice were more susceptible than hamsters to L. mexicaba and L. braziliensis panamensis. Balb/c mice were not susceptible to L. b. braziliensis. CBA/H mice showed a low susceptibility to infection while CD1 mice showed an intermediate response
Schistosoma mansoni: migration and attrition of irradiated and challenge schistosomula in the mouse
Authors: Mastin Avis J. , Bickle Q. D. , Wilson R. A.
Published: June 2009

The fate of irradiated, immunizing cercariae and challenge schistosomula was investigated in mice using a quantitative, histological technique which would appear to be more efficient in estimating parasite numbers in skin and lungs than does the tissue mincing and incubation recovery technique used previously by other workers. There was evidence for slight retardation of irradiated (20 krad.) parasite migration in skin, but death of schistosomula in the skin appeared negligible. It was observed that the majority of irradiated parasites remained in the lungs until at least day 21 after infection, and that most schistosomula observed at this time were dead. In mice immunized with irradiated cercariae there was no evidence of attrition of the challenge infection in the skin. The migration profile of challenge parasites in the lungs of immunized animals was not significantly different from that of normal parasites in the lungs of naive animals. Dead challenge parasites were observed in the lungs but their numbers were not considered great enough to account for the final attrition measured by perfusion. It is suggested that the remainder of the attrition of challenge schistosomula may occur in the systemic and/or hepatic portal circulation.
Effects of alcoholic extract from Ma-Klua (Diospyros mollis) on adults and larvae of the dwarf tapeworm, Hymenolepis nana in mice and on the infectivity of the eggs
Authors: Maki Jun , Kondo Asami , Yanagisawa Toshio
Published: June 2009

The anthelmintic effect of an alcoholic extract from a shrub, Diospyros mollis, popularly known as Ma-Klua in Thailand, on the adults and larvae of the dwarf tapeworm, Hymenolepis nana, in mice was studied in comparison with that of flubendazole. The experimentally infected mice were given a single oral dose of 10–1000 mg of Ma-Klua extract or flu-bendazole/kg body wt 1, 2, 3, 4, or 12 days post-infection and autopsied 14 days post-infection. Ma-Klua extract was effective in the elimination of adults (ED50 = 79 mg/kg) but not larvae. Drastic effects of Ma-Klua extract on the motility and structure of adults were observed and the number of the adults in mice decreased with time after administration of the drug 12 days post-infection. The small numbers of adults remaining in the host intestine 2 days after the drug administration showed severe damage in the gravid segments. These facts were thought to be responsible for the significant reduction in egg output observed 1 and 2 days after medication. Fresh eggs exposed to Ma-Klua extract in vitro and in vivo, or in vivo alone showed reduced infectivity. The effect of flubendazole on adults and larvae was minimal.
Ultrastructural studies on the cellular response of fish hosts following experimental infection with the plerocercoid of Ligula intestinalis (Cestoda: Pseudophyllidea)
Authors: Hoole D. , Arme C.
Published: June 2009

With the exception of gudgeon (Gobio gobio) infection of cyprinid fish with the plerocercoid of Ligula intestinalis is associated with a host-tissue response. The nature and specificity of this response has been investigated using transplantation techniques. In roach there is an intense cellular response to implanted Sepharose, Spurr's resin and L. intestinalis, irrespective of donor host species. However, tegument damage only occurs in gudgeon-Ligula and cultured ro&ch-Ligula which has been exposed to gudgeon-plasma. L1 and L2 cell types predominate within the cellular response. Once the host leucocytes have breached the tegument, they migrate over the basal lamina and penetrate into the sub-tegumental region. In gudgeon an intense cellular attack occurs against Sepharose, Spurr's resin, ro&ch-Ligula and cultured gudgeon-Ligula which had been implanted directly or exposed to roach plasma. Tegument damage only occurs in the latter. In contrast, neither direct implantation of gudgeon-Ligula nor cultured roach-Ligula which has been exposed to gudgeon plasma evokes a cellular response. It is suggested that in these two instances, as in natural infections of gudgeon, protective host proteins may be absorbed onto the surface of the parasite.
Unikaryon slaptonleyi sp.nov. (Microspora: Unikaryonidae) isolated from echinostome and strigeid larvae from Lymnaea peregra: observations on its morphology, transmission and pathogenicity
Authors: Canning Elizabeth U. , Barker Rosalind J. , Hammond Jill C. , Nicholas J. P.
Published: June 2009

A microsporidium, isolated from echinostome and strigeid larval trematodes in Lymnaea peregra, is described as a new species Unikaryon slaptonleyi sp.nov. The nuclei isolated at all stages of development, the disporoblastic sporogony and development in contact with host cell cytoplasm are used to assign the species to the genus Unikaryon. The absence of a vacuolar membrane to isolate the meronts and stages of sporulation from the host cell cytoplasm differentiates this genus from Encephalitozoon. Spores are uninucleate, have 17–21 turns of the polar filament coil and measure 5·0 × 2·8/μm fresh. U. slaptonleyi was isolated from rediae and metacercariae of Echinoparyphium recurvatum and sporo-cysts and cercariae of an unidentified strigeid trematode in L. peregra. It was transmitted in the laboratory to unidentified echinostomes in L. peregra and to unidentified strigeids in Planorbis planorbis by feeding the spores to field-collected snails from which cercariae were already emerging. In these natural and experimental hyperinfections the snail tissues were lightly infected but, in the helminths, much of the parenchyma and germinal tissue was destroyed, so that few cercariae were released and most of those were distorted. Similar heavy infections were produced in Fasciola hepatica in Lymnaea truncatula, when spores were fed to the snails 14 days after miracidial penetration, but even high doses (106 spores/snail) produced only light infections in Schistosoma mansoni in Biomphalaria glabrata, in only 2 out of 9 snails. No infections were obtained in larvae producing xiphidiocercariae in P. planorbis although echinostomes became infected under the same conditions. Of a number of aquatic and terrestrial arthropods tested for susceptibility by feeding or by inoculation of spores into the haemocoele, only Pieris brassicae became infected. In a small proportion of pupae surviving from larvae which had been inoculated with spores at 3rd or 4th instar, there was clear evidence of spore replication.
Junctional complexes in the inner cyst tissue of the cysticercoid ofHymenolepis diminuta(Cestoda)
Authors: Richards K. Sylvia , Arme C.
Published: June 2009

The inner cyst tissue development is anteriad and centripetal. The cells produce lamellar extensions which assume parallel alignment. The first contact points (approximately 4 days post-infection) establish heptalaminar (gap) junctions. Lamellar attenuation results in a decreased intercellular space, and at 5–6 days pentalaminar junctions (with fused outer plasmalemma leaflets to give an electron-dense, approximately 3 nm wide O–O line) occur. This is the first maturation (Ml) stage. The O–O lines are permeable to lanthanum, and evidence of their possible transformation from heptalaminar junctions is presented. Continued lamellar attenuation, associated with scolex retraction and subsequent growth, results in cytoplasmic occlusion and contact between the inner leaflets of thesamelamella. The resultant electron-dense I–I line is approximately 3 nm wide; the O–O line is now less electron-dense and thinner (approximately 2 nm). This final maturation (M2) stage, resembling vertebrate myelin, occurs over limited areas; closely adjacent regions either remaining at the M1 stage, or not displaying junctional complexes. Sincein vivoandin vitroexcystment can occur before the M2 stage, the inner cyst tissue is not considered to be protective against the definitive host. That the tissue may function in limiting nutrient flow, thus regulating the size of the presumptive adult, is discussed.
Schistosoma mansoni: tail loss in relation to permeability changes during cercaria–schistosomulum transformation
Authors: Howells R. E. , Gerken S. E. , Pinto-Ramalho F. J. , Kawazoe U. , Gazzinelli G. , Pellegrino J.
Published: June 2009

The hind-body region of Schistosoma mansoni cercariae observed in the scanning electron microscope demonstrates various stages of contraction which may be compared with those of living larvae which are secreting the acetabular gland contents.

No evidence for an extensive lesion was found in cercarial bodies which had shed their tails under experimental conditions. Experiments on the permeability of the larvae to sodium fluoride, methylene blue and amino acids demonstrated that tail loss significantly affects the permeability of the bodies although the effect is greater immediately after decaudation than at later times. Subsequent increases in permeability may be correlated with a change in the general body surface.
Assessment of the human and ecological hazards of microbial insecticides
Authors: Harrap K. A.
Published: June 2009

A comprehensive account is given of the evolution of registration guidelines and safety testing procedures for microbial insecticidal agents. Particular emphasis is given to the use of viruses for pest control and the various guidelines developed to assess their possible hazards. The likely gains and risks associated with using viruses are discussed. Several meetings have been held in the last 10 years to assess the hazards of virus insecticides. Some of these meetings have produced recommendations, some have developed guidelines for safety testing. These meetings are reviewed. The various guidelines developed for safety testing are critically evaluated and the UK Registration Criteria for Biological Agents used as Pesticides are reproduced in full. Examples of viruses that have been safety tested and registered for use are given and the criteria used are described. Conclusions are drawn on the merits of the guidelines presently available and the likely future development of safety testing schemes is considered.
Population interactions between a parasitic castrator,Probopyrus pandalicola(Isopoda: Bopyridae), and one of its freshwater shrimp hosts,Palaemonetes paludosus(Decapoda: Caridea)
Authors: Beck J. T.
Published: June 2009

Freshwater shrimp,Palaemonetes paludosus, infected by the bopyrid isopod,Probopyrus pandalicola, occurred as far as 33 km upstream in many coastal rivers and canals throughout Florida. Free-swimming isopod larvae and the intermediate copepod host,Acartia tonsa, were collected in the plankton of the Wakulla River, and it appeared that cryptoniscus larvae swam at least as far as 13 km upstream to infect the definitive shrimp host after leaving the copepod in brackish water. In the Wakulla River infection levels ranged from 87·5 to 100%. In contrast, at McBride's Slough infection levels fluctuated from 0·9 to 93·2%. In the St Marks River the frequency of infected shrimp gradually increased from 0% upstream to 96%, 6 km further downstream. A significantly greater percentage of female than male hosts were infected, but only females of size classes less than 31 mm long had a greater frequency of infection. FemaleP. pandalicolawere greatly under-dispersed (coefficient of dispersion (s2/x¯) less than 1) throughout the host population; 99·6% of the infected hosts carried only 1 female parasite. Control ofP. pandalicolaat the infrapopulation level is probably accomplished by some mode of intraspecific competition, and control at the suprapopulation level occurs through an upstream limitation of the transmission range of the cryptoniscus larval stage. Host–parasite interactions appear to be unstable.
Immunity toSchistosoma mansoniin congenitally athymic, irradiated and mast cell-depleted rats
Authors: Ford M. J. , Bickle Q. D. , Taylor M. G.
Published: June 2009

Immunity toSchistosoma mansoniwas investigated in congenitally athymic (Nu/Nu) rats, irradiated rats and in mast cell-depleted rats. Nu/Nu rats failed to develop significant resistance following vaccination with irradiated cercariae, although Nu/Nu recipients of serum from vaccinated Fischer rats (VRS) manifested resistance comparable to heterozygous controls, suggesting that T-cells were required in the induction of resistance but were not involved in the efferent arm of antibody-dependent elimination. Radiosensitive cells (including eosinophils, basophils, neutrophils, lymphocytes and mast cells) were apparently not essential for the antibody-dependent elimination of lung or post-lung stages since irradiated (700–750 rad.) recipients of VRS manifested comparable degrees of resistance to unirradiated controls in spite of a greater than 85% reduction in total blood leucocyte counts after irradiation. Depletion of 99 % of tissue mast cells by treatment of rats with Compound 48/80 had no significant effect on the attrition of a challenge infection in rats rendered immune by vaccination with irradiated cercariae or by transfer of VRS. However, there was a significant increase in worm recovery in unimmunized and mast cell-depleted or irradiated rats, indicating that mast cells and perhaps other radio-isotope sensitive cells may be involved in innate resistance.