bluuebunny/crossref_metadata_2025 huggingface dataset:
The uptake in vitro of dyes, monosaccharides and amino acids by the filarial worm Brugia pahangi
Authors: Chen S. N. , Howells R. E.
Published: June 2009

The uptake in vitro of various substances by Brugia pahangi was investigated using infective larvae obtained from Aedes aegypti and worms removed from Meriones unguiculatus at 2, 3, 10, 20 and 90 days post-infection. Worms incubated in growth medium 199 containing 1% Trypan blue possessed demonstrable dye in the oral orifice, the anterior oesophageal lumen and the external openings of the vulva and the cloaca or anus but the dye was not found in the gut lumen even after incubation for 24 h. No uptake of ferritin particles into the intestine of the worms was found and no fluorescence could be demonstrated in the gut lumen of worms incubated in medium containing 50% (v/v) fluorescein isothiocyanate-conjugated calf serum for up to 24 h. Trypan blue uptake by the gut of Aspiculuris tetraptera was clearly observed after incubation for several hours. The uptake of D-glucose and L-leucine by B. pahangi was demonstrated using autoradiographic and scintillation counting techniques and incorporation into worm tissues was detected. Glucose was found to be readily incorporated in the apical, glycogen-rich areas of the myocytes of worms of all ages studied and in the uterine epithelium of the adult female. In contrast, a lower incorporation of D-glucose was found in the eggs, embryos and vas deferens and especially in the gut. The incorporation of L-leucine occurred throughout the tissue of the worms during a 30 mm incubation. Labelling was also located over the surface of the cuticle of the worms, when incubated for a period of 15 to 60 mm in L-[3H]leucine. Scintillation counting techniques demonstrated that there was no uptake of 14C-labelled L-glucose or sucrose by B. pahangi. The data presented on the uptake in vitro of nutrients or other compounds by infective larvae and adult stages of B. pahangi did not demonstrate an intestinal route of uptake but indicated that the transcuticular route of uptake may be employed.
Different levels of acquired immunity to Schistosoma mansoni in two strains of hamster
Authors: Smith M. A. , Clegg J. A.
Published: June 2009

A primary infection with Schistosoma mansoni, of 5 or more weeks duration, stimulated a high level of resistance to a challenge infection in the WO outbred strain of golden hamster. In sharp contrast, the LGN strain showed no statistically significant immunity to reinfection in most experiments and where detected the level of resistance was only about half that observed in the WO strain. Immunity to reinfection was assayed with the lung recovery method which assesses resistance a few days after challenge and with the conventional perfusion assay which measures immunity 6 weeks after challenge. Wide differences in the immune response to S. mansoni in different strains of the same host species have not been reported previously.
Transplantation ofHymenolepis diminutainto naive, immune and irradiated mice
Authors: Hopkins C. A. , Zajac A.
Published: June 2009

Almost 100% of 7- to 10-day-oldHymenolepis diminutabecame established when surgically transplanted from donor mice into the duodenum of naive recipient mice. Transplanted tapeworms survived 8–12 days, by which time they had survived much longer in total than they would have done in the donor. Mice previously immunized by a primary infection rejected transplants within 4 days. Sub-lethal irradiation (550 rad) delayed rejection by immune mice but such mice still rejected worms much more quickly than did naive mice.

Surgery was shown to delay by 2–3 days the rejection of worms by naive mice, and the importance of circumventing surgery by administering the wormsper osis emphasized.

Prospects for reconstituting irradiated immune mice are consideredvis-à-viswork with nematodes, and the differences which, on present knowledge, appear to exist between nematode and cestode rejection are briefly discussed.
Genetic structure of Anisakis physeteris, and its differentiation from the Anisakis simplex complex (Ascaridida: Anisakidae)
Authors: Mattiucci S. , Nascetti G. , Bullini L. , Orecchia P. , Paggi L.
Published: June 2009

The genetic structure of Anisakis physeteris from the Mediterranean Sea has been analysed electrophoretically at 22 enzyme loci. The samples studied, although differing in the life-stage (larvae and adults), and in the host (the fishes Micromesistius poutassou and Trachurus trachurus, and the sperm whale Physeter macrocephalus) were genetically homogeneous. Of these loci 11 (Ldh, Sod, Np, Adk-2, Pgm-1, Est-1, Est-2, Acph-1, Acph-2, Lap-2 and Ca) were found to be monomorphic, while the other 11 (Sdh, Mdh, ldh, 6-Pgdh, G3pdh, Got, Adk-1, Pgm-2, Lap-1, Mpi and Gpi) showed from 2 to 7 alleles. The following values of genetic variability were estimated: He = 0·ll, P = 0·50, A = 1·95. Distinct alleles were found between A. physeteris and the A. simplex complex at 19 out of the 22 loci studied, and only few rare alleles were shared at the remaining 3 loci. The genetic divergence between A. physeteris and A. simplex A and B is therefore very high, the values of Nei’s index D being 7·384 and 6·443 respectively (I = 0·001 and 0·002). The assignation of A. physeteris and the A. simplex complex to two distinct subgenera, Skrjabinisakis and Anisakis, as proposed by Mosgovoy on a morphological basis, appears to be fully justified according to our genetic data.
Antibody dependent cell-mediated cytotoxicity againstTrypanosoma cruzi
Authors: Abrahamsohn I. A. , Da Silva W. D.
Published: June 2009

This paper describesin vitroantibody dependent cytotoxicity againstTrypanosoma cruziepimastigotes by normal mouse splenic lymphocytes. Cytotoxicity was expressed as the percentage reduction in the number of motile parasites upon incubation with lymphocytes at 37 °C in a denned medium. Failure of the non-motile parasites to regain motility and their ensuring degeneration at 28 °C in liver infusion tryptose (LIT) medium confirmed loss of motility as a criterion of cytotoxicity. Incubation ofT.cruziat 37 °C for 18 h in a defined mediumper sedid not interfere with motility but was followed by a lag phase of the growth curve in LIT medium at 28 °C. The lag phase was prolonged forT. cruziwhich had previously been incubated at 37 °C in the absence of cells.
Stimulation of the activity ofSchistosoma mansonimiracidia by snail–conditioned water
Authors: Mason P. R.
Published: June 2009

A dark-ground photographic technique was used to analyse the reactions ofSchistosoma mansonimiracidia to homogeneous solutions of snail–conditioned water (SCW). The most significant effect of this water was to increase miracidial turning. This effect was maintained under both acid and alkaline conditions, after passage of the SCW through a mixed bed resin and after chelation of either calcium or both calcium and magnesium ions. The stimulant in the water was unaffected by trypsin but was protease–sensitive, suggesting its possible identity as a peptide. The importance of ‘active spaces’ rather than concentration gradients in miracidial host–location was emphasized.
Freeze fracture studies on the interaction between the malaria parasite and the host erythrocyte inPlasmodium knowlesi infections
Authors: McLaren Diane J. , Bannister L. H. , Trigg P. I. , Butcher G. A.
Published: June 2009

The freeze fracture technique has been used to study the internal cyto-architecture of the surface membranes of the parasite and erythrocyte inPlasmodium knowlesiinfections. Six fracture faces, derived from the plasma membrane and 2 pellicular membranes, have been identified at the surface of the free merozoite. The apposed leaflets of the 2 pellicular membranes show the characteristic features of E fracture faces, a result compatible with the view that the pellicular membranes line a potential cisterna. There is evidence to suggest that there may be changes in the distribution and density of the integral proteins in the merozoite plasma membrane at invasion. Furthermore, vesicles consisting of stacked membranes occur within and around the erythrocyte invagination at invasion; it is suggested that these vesicles are released from the merozoite rhoptries. Formation of the parasitophorous vacuole is accompanied by dramatic changes in the density and distribution of intra-membraneous particles (IMP) in the vacuolar membrane. Initially there is a great reduction in particle numbers, but subsequently the particles reappear and show reversed polarity. The possible causes and implications of these changes are discussed. The intra-erythrocytic parasite synthesizes new transmembrane proteins as development proceeds, and the trophozoite and schizont stages of development are characterized by the appearance of circular, particle-free regions in the parasite plasmalemma. There is a decrease in the density of transmembrane proteins in the erythrocyte plasma membrane during parasite maturation, and the P face IMP show the characteristic features of aggregation.
The ultrastructure of the surface of Diplocystis schneideri Kunstler (Sporozoa: Eugregarinida) a parasite of Periplaneta americana
Authors: Rotheram Susan , Lackie J. M.
Published: June 2009

Ultrastructural observations of the surface of Diplocystis schneideri reveal a folded, multilaminate membrane, similar to that found in other eugregarines, covered with a layer of fibrous material. It is suggested that this fibrous material is a product of the haemocytes of the host, Periplaneta americana.
Chemotherapy and the immune response in parasitic infections
Authors: Targett G. A. T.
Published: June 2009

There are comparatively few studies concerned specifically with chemotherapy of parasitic infections and its relationship with the immune status of the host being treated. In one sense this is hardly surprising. The disciplines of chemotherapy and immunology have developed independently, and the search for effective drugs has for the most part been an empirical process; when a compound showing some activity has emerged the tendency has been to look for analogues with even greater parasiticidal properties rather than to consider whether effectiveness of the parent compound could be improved if the immune status of the host were different. In many cases, test systems for drug development have actually been selected to reduce as far as possible the complications f an immune response. Thus acute, fatal infections are commonly used for the screens, and questions such as the level of specific resistance at the time of treatment, immunodepression by the parasite, and increased resistance to challenge following chemotherapy are generally irrelevant.
Tegumental disruption with Triton X-100 and its effects on longitudinal muscle function in male Schistosoma mansoni
Authors: Depenbusch J. W. , Thompson D. P. , Pax R. A. , Bennett J. L.
Published: June 2009

Longitudinal muscles in adult male Schistosoma mansoni appear to remain in almost all respects functional after tegumental disruption by Triton X-100. Responses to high K+, ouabain, low temperature, praziquantel and neurotransmitters are still present. Muscle membrane potentials remain near those of control animals and lanthanum nitrate is still excluded from the muscle after the Triton treatment. Although muscle contractility remains after tegumental disruption, sodium and calcium levels, as measured by plasma emission spectroscopy, increase by 20–30% while potassium and magnesium levels decrease by 15%. 45Ca2+ accumulation is double that of control animals. Upon exposure to a bathing medium lacking Ca2+, Triton-treated animals lose responsiveness to high K+, ouabain, low temperature and praziquantel more rapidly than do control animals. D-600, which effectively blocks the high K+ response in control animals, has no measurable effect on the high K+ response in Triton-treated animals, suggesting that voltage-dependent Ca2+ channels are present in the tegument.
Secondary infections of Hymenolepis diminuta in mice: effects of varying worm burdens in primary and secondary infections
Authors: Befus A. D.
Published: June 2009

In one (1c) and six (6c) cysticercoid primary infections of Hymenolepis diminuta in NIH (inbred) and CFLP (outbred) male mice 6±1 weeks old > 85% of the worms established but were rejected (destrobilated or expelled) subsequently. Rejection occurs more quickly in 6c infections than in 1c infections. Considerable worm growth occurs in 1c and 6c primary infections but worms from 6c infections weighed less than worms from 1c infections on all days studied.

Expulsion of H. diminuta does not occur more rapidly in secondary infections than in primary infections; loss of 6c secondary worms occurs at the same rate as 6c primary worms but 1c secondary worms survive longer than 1c primary worms. Although worms are not lost more quickly in secondary than in primary infections, they are affected at an early age by the immune response which stunts their growth. Increasing the intensity of primary and secondary infections increases the severity of stunting of secondary worms.

The results are discussed and it is suggested that immune responses to Hymenolepis spp. in rodents are common but that thresholds of worm numbers exist below which appreciable worm loss does not occur. Stunting due to crowding, which generally is attributed to inter-worm competition, may be in part immunologically mediated. For future immunological studies attempting to induce secondary responses to H. diminuta in mice, worm growth, not survival, is the criterion to evaluate.
Effect of gamma-irradiation on oocysts of Eimeria necatrix
Authors: Singh Jasmer , Gill B. S.
Published: June 2009

Effect of gamma radiation on oocysts of Eimeria necatrix was investigated. It was observed that oocysts exposed to 200 kR or above did not sporulate. Irradiation at 10–150 kR caused a progressive decrease in sporulation. Irradiation affected normal development of unsporulated oocysts as the zygote protoplasm divided into unequal masses or was shattered into granules.

Increase in the intensity of irradiation of sporulated oocysts resulted in the progressive decrease in severity of the resultant infections in chicks and their effects – mortality, type of lesions developed, total oocyst production and immunity produced – were comparable with infections induced by decreasing the number of unirradiated oocysts. Infection produced by 1000 unirradiated oocysts was comparable with that resulting from 50000 oocysts irradiated at 25 kR. Infection obtained with 20000 unexposed oocysts approximated to that produced by 50000 ooeysts irradiated at 2·5 kR. It was concluded that irradiation abolished infectivity of the oocysts/sporozoites rather than bringing about attenuation of the parasite.
Separation of erythrocytes infected with murine malaria parasites in metrizamide gradients
Authors: Eugui Elsie M. , Allison A. C.
Published: June 2009

Density gradients with metrizamide, a tri-iodinated benzamido derivative of glucose, have been used to separate erythrocytes infected with 3 species of murine plasmodia. Good separations were obtained of uninfected erythrocytes from erythrocytes containing parasites in different developmental stages. With metrizamide solutions, the densities required for isopycnic separation can be obtained without hypertonicity or high viscosity, and the viability and those aspects of the metabolism of parasites and erythrocytes that we measured are not detectably modified by exposure to these solutions. This type of separation has many possible applications to biochemical and immunological investigations.
Brugia malayi microfilaraemia in mice: a model for the study of the host response to microfilariae
Authors: Grove D. I. , Davis R. S. , Warren K. S.
Published: June 2009

Microfilariae of Brugia malayi were obtained from the peritoneal cavities of infected gerbils and were then injected intravenously into mice. A sub-periodic, nocturnal microfilaraemia was produced. The level of microfilaraemia was proportional to the number of parasites injected, with approximately 1–3% of microfilariae being found in the peripheral circulation. The duration of microfilaraemia was proportional to the number of parasites injected; it subsided by 30 days after injection of 104 microfilariae but was still present at a low level 120 days after injection of 2 × 105 microfilariae. A transient splenomegaly developed after injection of microfilariae. Histopathological examination revealed large numbers of microfilariae free in the lumens of pulmonary small blood vessels and without any accompanying inflammatory reaction. Lesser numbers of microfilariae were seen in the cardiac blood and hepatic and renal blood vessels for the first few days after injection. There was cellular proliferation in the splenic white pulp and vascular congestion of the red pulp. Microfilariae labelled with 51Cr were injected intravenously; 57% of radioactivity was found in the lungs, 8·5% in the liver and 2·9% in the spleen. Mice developed immediate hypersensitivity reactions to B. malayi antigen by 4 weeks after injection, but Arthus and delayed hypersensitivity reactions were not seen at any time. When mice which had been injected 5 months previously were challenged with a 2nd injection of microfilariae, there was an accelerated clearance of parasites over 2 weeks and a marked peripheral blood eosinophilia developed. In contrast with natural infections, in which the continuous production of microfilariae complicates assessment, this model provides a system in which factors controlling the circulation of microfilariae in the bloodstream can be studied independently.
Processing of the precursor to the major merozoite surface antigens ofPlasmodium falciparum
Authors: Holder A. A. , Sandhu J. S. , Hillman Yvonne , Davey Lynne S. , Nicholls S. C. , Cooper Helen , Lockyer M. J.
Published: June 2009

Specific sequences derived from the gene for the precursor to the major merozoite surface antigens (PMMSA) ofPlasmodium falciparumhave been expressed inEscherichia coliand the products have been used to produce antibodies. These antibodies, together with monoclonal antibodies, have been used to investigate the form of the PMMSA protein associated with merozoites. Polypeptide fragments derived by processing from the PMMSA protein have been detected in extracts of merozoites and assigned to locations within the PMMSA coding sequence.
Inhibited development of Ostertagia ostertagi in relation to production systems for cattle
Authors: Smeal M. G. , Donald A. D.
Published: June 2009

On a coastal farm in New South Wales where beef and dairy cattle production was carried on side-by-side, separate pasture plots were contaminated with eggs of Ostertagia ostertagi by calves from each production system in autumn, winter or spring. Successive groups of parasite-free tracer calves grazed on the plots for 14 days at 4-week intervals and were then killed for worm counts 14 days after removal from pasture. On all plots, the proportion of inhibited early 4th-stage larvae in tracer calves reached a maximum in spring, and was consistently and very significantly higher in calves which grazed plots contaminated with O. ostertagi of beef cattle origin. Factors which may be responsible for this difference between beef and dairy cattle populations of O. ostertagi are discussed.
Microelectrode studies of the tegument and sub-tegumental compartments of maleSchistosoma mansoni: anatomical location of sources of electrical potentials
Authors: Bricker Connie S. , Pax R. A. , Bennett J. L.
Published: June 2009

Histological studies using horse-radish peroxidase (HRP) as a marker, injected iontophoretically through a recording electrode, have indicated the origins of potentials encountered upon advancement of the electrode into and beneath the dorsal surface of adult maleSchistosoma mansoni. The first potential encountered, having a value of – 51 ± 0·6 mV originates across the outer tegumental membrane. The next potential has a value of — 28 ± 0·6 mV and originates in the muscle masses underlying the tegument. Finally, a potential having the value — 10 ± 0·5 mV originates within the basal lamina and the interstitial fibres and extracellular space surrounding the muscle. Altering ion concentrations in the bathing medium (i.e. high K+, low Na+, zero Ca2+, low Cl−, high Li+) depolarizes all three potentials. External applications of ouabain and the anti-schistosomal, praziquantel, also cause depolarization of the potentials. It appears that the muscle potential and the tegumental potential are primarily K+-dependent. The depolarizing effects of ouabain, LiCl and low Na+suggest that active transport is important in the maintenance of the muscle potential, just as is the case for the tegumental potential. There appears to be a close correlation between changes in the tegumental, muscle and extracellular space potentials. The correlation between tegument and muscle potential changes might be explained by junctional complexes between tegumental cell bodies and muscle cell bodies.
Microelectrode studies of the tegument and sub-tegumental compartments of male Schistosoma mansoni: an analysis of electrophysiological properties
Authors: Thompson D. P. , Pax R. A. , Bennett J. L.
Published: June 2009

Standard intracellular microelectrode techniques were used to determine the electrical properties of the tegument and sub-tegumental regions in male Schistosoma mansoni. Three distinct compartments of electrical potential were observed. The resting potentials recorded in these compartments of –45·9±2·5 mV (Eteg), –22·0±1·1 mV (E2) and – 4·7±0·3 mV (E3) corroborate those previously reported by Fetterer, Pax & Bennett (1980) and Bricker, Pax & Bennett (1981). Input resistance was measured in each compartment and was found to be 4·5 MΩ (tegument), 9·2 MΩ (E2) and 3·5 MΩ (E3). Time-constants for the tegument, E2 and E3 were 0·24±0·01 msec, 0·25±0·01 msec and 0·13±0·01 msec, respectively. Multiple electrode experiments revealed that the tegument and E2 compartment are electrical syncytia with similar current-spreading capabilities. Low resistance pathways also appear to connect the tegument and E2 region, since electrotonic signals initiated in either of those compartments experience only a 15–25% reduction upon passing into the other. Injecting large (> 200 nA) depolarizing current pulses into the tegument or E2 compartment often resulted in the initiation of active membrane responses. These spikes were highly variable, ranging from 4 to 75 mV in magnitude (occasionally overshooting zero potential by as much as 25 mV) and from 10–40 msec in duration. The responses were not actively propagated along the parasite, and their decay over distance was approximately equal to that predicted on the basis of length constant values obtained from electrotonic signals. The addition of a non-diffusible solute to the recording medium resulted in a significant reduction in the current-spreading capacity of both the tegument and E2 compartment. Coupling ratios between the tegument and E2 compartment were decreased, and the input resistance for both compartments increased, while resting potentials remained constant. Active responses could not be evoked in schistosomes exposed to the hyperosmotic medium.
Thymus-independent crypt hyperplasia and villous atrophy in the small intestine of mice infected with the trematodeEchinostoma revolutum
Authors: Bindseil E. , Christensen N. Ø.
Published: June 2009

Conventional mice and congenitally athymic, nude mice were infected with 20 metacercariae of the intestinal trematodeEchinostoma revolutum. The sequential events in the pathological changes in the intestine were studied at different intervals post-infection. By day 11 onwards the conventional mice displayed dilatation of the region of the intestine which harboured the parasites. The mucosa in the dilated region showed marked crypt hyperplasia, villous atrophy and subepithelial fibrosis as the most conspicuous features which, together with a hypertrophy of the muscular layers, made the wall of the gut in the dilated region thicker than normal. The changes were thymus-independent as they were found to be as severe in the athymic, nude mice as in the conventional mice. The main histological features observed in the mice are discussed in relation to other conditions with similar changes, such as coeliac disease, nippostrongyliasis and trichinellosis. It is concluded that the present results support the view that there may be more than one effector mechanism of the change.
Degenerating exo-erythrocytic forms of Plasmodium berghei in rat liver: an ultrastructural and cytochemical study
Authors: Jap P. H. K. , Meis J. F. G. M. , Verhave J. P. , Meuwissen J. H. E. Th.
Published: June 2009

Morphological and cytochemical aspects of the host response to almost mature exo-erythrocytic forms (EEF) of Plasmodium berghei in rat hepatocytes were studied by electron microscopy. Young stages (< 47 h) never evoked a local reaction. Two types of nearly mature EEF (47–51 h) could be distinguished, normal (EEF type I) and those that were the target of infiltrating cells (EEF type II). The latter were in a stage of early or advanced degeneration and generally exhibited increased electron density, especially in the contents of their peripheral vacuoles. Neither type of EEF exhibited detectable enzyme activity, although host cell enzymes, such as peroxidase and 5-nucleotidase, were demonstrable. However, the infected liver cell appeared permeable to ruthenium red whereas non-infected hepatocytes were not. When signs of degeneration were present, as shown by the increasing density of the cytoplasm, loss of enzyme activities occurred. The encompassing mononuclear cells were identified as true monocytes, non-monocyte-derived and monocyte-derived macrophages by their endogenous peroxidase activity. Macrophage filopodia penetrated and cleaved both hepatocyte and parasite cytoplasms. Subsequently, digestion and clearing of the remnants took place. This study clearly demonstrated that a proportion of the intra-hepatocytic EEF was destroyed by macrophages before they were able to mature completely and release their merozoites.
Temporal changes in aggregation: a laboratory study
Authors: Scott Marilyn E.
Published: June 2009

Changes in the variance to mean ratio and the parameter k of the negative binomial distribution were used to study temporal changes in the degree of aggregation of the monogenean parasite, Gyrodactylus turnbulli in free-running laboratory populations of the guppy, Poecilia reticulata. The parasite undergoes recurrent epidemic cycles in the host population under conditions of regular immigration of uninfected guppies. During the early phase of the epidemic, heterogeneity among fish together with direct reproduction are thought to contribute to the increasing degree of aggregation. During the increasing phase of the epidemic cycle, parasites become increasingly aggregated in the host population, presumably because of the direct reproduction of the parasite on the surface of a single host. As the peak prevalance and abundance are approached, the parasites become less aggregated with lowest clumping occurring during the declining phase of the cycle. This is thought to be a function of density-dependent death of infected hosts, and density-dependent reduction in parasite survival and reproduction on hosts that recover from infection. This study clearly indicates that the variance to mean ratio and the parameter k of the negative binomial distribution do not quantify the same aspect of the frequency distribution. It is suggested that the variance to mean ratio is a better measure when the prevalence and−or mean burden are changing and when the tail of the distribution is of particular interest, and that k may be a preferred parameter when the zero class or the lightly infected hosts are of primary interest.
Strongyloides ratti (homogonic): the time-course of early migration in the generalized host deduced from experiments in lactating rats
Authors: Wilson P. A. G. , Steven Gillian E. , Simpson Norma E.
Published: June 2009

Unsuckled mother rats given a 1 h suckling stimulus 3 h after subcutaneous injection of an exact dose of homogonic Strongyloides ratti allow fewer worms to develop in their intestines by day 8 than nulliparous rats (Wilson & Simpson, 1981). This effect is studied in more detail in terms of the length of time between weaning and stimulus (W → S) and injection and stimulus (I → S). It was observable with a W → S of 30 h but this and a period of 5 h were less effective than 24 h. With W → S constant at 24 h, significantly more worms developed in mothers when I → S was 24 h compared to 3 h and 10 h (P < 0·005). The data, combined with those from nulliparous controls, are presented as a measure of the change with time of numbers of larvae in that compartment of the system which gives access to the stimulated mammary gland. It is argued that the particular compartment is the local lymph node draining the injection site and that the kinetics deduced are applicable to migration in the rat in general
Naturally occurring agglutinins against trypanosomatid flagellates in the haemolymph of insects
Authors: Ingram G. A. , East Janet , Molyneux D. H.
Published: June 2009

In vitrostudies of the behaviour of the trypanosomatid flagellatesTrypanosoma bruceiandLeishmania hertigiin the presence of cell-free haemolymph of locusts,Schistocerca gregariaand cockroaches,Periplaneta americanarevealed the presence of parasite agglutinins. The range of normal values of agglutination titres was 2−4to 2−13. Physico-chemical treatment of haemolymph indicated that these agglutinins are protein or glycoprotein in nature and are only partially affected by heat treatment below 65°C, at which temperature incubation of haemolymph for 30 min abrogated all agglutination. Agglutination was not dependent on the presence of Ca2+or Mg2+. Prior infection of locusts and cockroaches withT. bruceiandL. hertigisignificantly increased agglutinin titres between Days 4 and 6 in cockroaches (P< 0·05) and from Days 2 to 4 whenL. hertigiwas inoculated into locusts. The induced differences in titres observed in locusts infected withT. bruceiwere not significant. Lysozyme levels were significantly increased after inoculation ofT. bruceiinto cockroaches compared with placebo-inoculated and uninoculated controls.L. hertigiinoculation produced significant increases in lysozyme levels compared with controls between Days 1 and 7 in locusts and 3 to 6 in cockroaches. These studies indicate that, at least in easily manipulated model systems, induced responses to intrahaemocoelic inoculation to trypanosomes andLeishmaniacan occur. As far as we are aware this is the first report of an induced response of an insect to such important parasites. The possibility that induced responses in natural vectors to these parasites occurs requires investigation.
A new technique for the extraction of Nematodirus battus eggs from sheep faeces
Authors: Coadwell W. J. , Martin Jean , Ward P. F. V.
Published: June 2009

Details are given of a method for the separation of the eggs of the nematode Nematodirus battus from sheep faeces. Faecal pellets obtained from worm-free lambs experimentally infected with N. battus were homogenized and passed through a graded series of metal sieves. The material retained in a 53, µm aperture sieve was transferred to a cylindrical column and the eggs were cleaned and separated from other suspended material by controlled differential flotation using tap water. A model experiment indicated that, within limits, the principle held for any size of tower. The density distribution for eggs at the morula stage of development was determined. Suggested flow rates for a specified tower are given.
Microgametogony of Sarcocystis hirsuta in the intestine of the cat
Authors: Dubey J. P.
Published: June 2009

The development of microgamonts was studied in the small intestine of a 2-day-old cat after oral inoculation with 107 bradyzoites of Sarcocystis hirsuta. The cat was given bradyzoites in 2 doses at 2 h apart and killed 4 h later. Gamonts were seen in parasitophorous vacuoles of goblet cells in the epithelium of the small intestine. All stages of microgametogony, from the single nucleated meront to fully developed gametes, were seen. Microgamonts measured 6·9 × 6·0 μm and macrogamonts measured 6·0 × 5·0 μm.
Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): the capacity of adult worms to survive following transplantation to recipient mice
Authors: Behnke J. M. , Williams Diane J. , Hannah J. , Pritchard D. I.
Published: June 2009

Chronic primary infections with Heligmosomoides polygyrus (Nematospiroides dubius) are still relatively poorly documented, particularly in relation to the role of host resistance in limiting worm survival. In the present work the duration of infection with H. polygyrus was studied in CFLP mice given doses of infective larvae ranging from 50 to 500 L3. The least heavily infected (50 L3) group ceased egg production earliest (week 36) whereas eggs were still detected in the faeces of mice given 500 larvae in week 42. At autopsy (week 42) mice given 50 larvae had virtually lost their entire worm burden with 5 out of 11 mice still harbouring a single worm each. However, all the mice in the group given 500 larvae were still infected, the highest worm burden being 93. The concentration of serum IgGl and specific antibody was highest in mice given 500 larvae, but sera taken from mice with declining worm burdens 19–38 weeks post-infection did not contain detectable host-protective antibody. During the course of infection in CFLP mice, H, polygyrus sustained irreversible changes in its capacity for subsequent survival. Thus, adult worms transferred to naive mice 2, 7, 14, 30 or 36 weeks post-infection did not live longer than worms of a comparable age in the respective donor group. In contrast, primary infection worms taken from jirds in which expulsion is usually completed by 6 weeks post-infection, re-established in mice and survived considerably longer than in the group of donor jirds. These results were discussed in relation to the possible interactions between parasite senility and immunomodulation, and host resistance in limiting primary infections with H. polygyrus in mice and jirds.
Use of75Se tracer and autoradiographic techniques in the study of schistosomiasis
Authors: Chandiwana S. K.
Published: June 2009

The paper provides an overview of recent studies on the use of75Se to tag larval schistosomes and to monitor their migration and distribution patterns in naive mice and those previously exposed to cercariae. The principles and techniques of radioassay and autoradiography in studying various aspects of75Se-labelled larval schistosomes are described. The main shortcoming of radioassay in monitoring location and movement of labelled schistosomula is that some of the label dissociates from the schistosomula and accumulates in host tissues, notably the liver. Dissociated label is indistinguishable from schistosomula-bound label making monitoring of parasite migration extremely difficult. This difficulty is overcome by compressed tissue autoradiography where labelled schistosomula can be seen as reduced silver foci on an autoradiographic film, whereas dissociated label is too diffusely distributed to produce such reduced silver foci. Furthermore, using autoradiography, quantitative information on parasite migration in normal and immunized laboratory animals can be obtained that would be impossible using traditional recovery techniques. In addition to using75Se tracer in migration studies, the radio-isotope has potential for elucidating various aspects of schistosome transmission ecology and snail population dynamics in natural waters.
Penetration and migration routes of Schistosoma japonicum miracidia in the snail Oncomelania hupensis
Authors: Xia M. Y. , Jourdane J.
Published: June 2009

The routes of penetration and the strategies of invasion of Schistosoma japonicum miracidia in the snail vector Oncomelania hupensis were observed in a histological study. In all species of the genus Schistosoma, it is usually assumed that the miracidia achieve penetration through the tegument. Our results showed that at least 57% of S. japonicum miracidia penetrated the snail by natural openings (branchial cavity, mouth and rectum). Throughout the invasion phase, the larvae were observed in all the tissues and organs with the exception of the genital gland. The spatial distribution of parasites in the snail revealed that the migration towards the visceral organs such as the kidney, heart and sinuses (which are the most usual microhabitats of the mother sporocysts of S. japonicum) appeared to take place via the circulatory system. Using natural openings as routes for penetration probably provides a selective advantage in a host–parasite system in which the target mollusc is amphibious: we presume that the miracidia inside these natural openings are protected against desiccation when the snail leaves the water, and that they can subsequently invade the tissues.
In vitro cultivation of adult Litomosoides carinii: evaluation of basic culture media, gas phases and supplements
Authors: Mössinger J.
Published: June 2009

Adult Litomosoides carinii, recovered from cotton rats (Sigmodon hispidus) 4–5 months post-infection (p.i.), were cultivated in vitro with emphasis on investigations into the development of intra-uterine embryonic stages. Baseline values for the embryonic status of female worms were established immediately after recovery from the hosts. In such females, on average, 16% of the intra-uterine stages were fully formed microfilariae while the remainder belonged to the early embryonic classes that were characterized. For the evaluation of culture success, apart from survival of worms in vitro, the rate of microfilariae development (mf rate) served as a major parameter. Of the five basic culture media RPMI 1640, F12, L15, NCTC 135, and IMDM, tested without supplementation, RPMI 1640 yielded by far the best results (survival = 14 days; mf rate = 41%), and was therefore chosen as the routine medium. In comparison with 5% CO2 in nitrogen, a gas phase of 5% CO2 in air was superior, although the resulting oxygen tension of 138 mmHg in the medium was not physiological. Addition of 10% newborn or foetal bovine serum to the medium in some cases distinctly influenced results. Effects of different batches of sera varied from ‘filaricidal’ to ‘very promoting’. Co-cultivation of worms and Sigmodon cells, or rhesus monkey LLCMK2 cells, only marginally improved results. Of the serum substitutes Ultroser G, BMS, and Clex, the latter had a moderately promoting effect. The protein supplements bovine serum albumin, transferrin and haemoglobin significantly improved results, and could replace certain batches of serum. Supplementation with the haemin moiety alone was less effective than with haemoglobin. The anti-oxidants glutathione plus ascorbic acid proved beneficial in combination with a serum supplement only. Results from other experiments with multiple supplementation also suggest that various supplements may act only in a synergistic manner. The longest average time that adult L. carinii survived in vitro was 3–4 weeks. The highest mf rate was 78%, which indicated that all text-abstract embryonic stages present in the uteri of a female at the start of culture completed their development to microfilariae, however, oogenesis ceased in vitro. The parameters for embryonic development employed proved to be highly sensitive for the judgement of various culture conditions.
The effects of oxytetracycline onTheileria parva in vitro
Authors: Spooner P. R.
Published: June 2009

When bovine peripheral blood leucocytes were infected withTheileria parvasporozoites, immediate treatment with oxytetracycline (OTC) inhibited the development of sporozoites to mature schizonts. The extent of inhibition was dependent on drug concentration and duration of treatment. Concentrations of 5μg/ml OTC, or higher, for 8 days completely inhibited the establishment of schizonts and their ability to transform host cells. A cytostatic effect on schizont-infected cell lines was found with three tetracyclines and was also demonstrated on uninfected lymphoblasts. The parasites were found to be sensitive t OTC during development to schizonts, but when mature and established within host cells, schizonts were not demonstrably affected. The infectivity of sporozoites and the binding of sporozoites to lymphocytes were not directly inhibited by OTC. The results may explain the action of tetracyclines when used prophylactically during immunization against East Coast fever, and also the reasons for the ineffectiveness of these drugs when used therapeutically during patent disease.
Mitochondria of mammalianPlasmodiumspp.
Authors: Fry M. , Beesley J. E.
Published: June 2009

Highly purified mitochondrial fractions have been isolated from the intraerythrocytic stages of two mammalianPlasmodiumspp.,Plasmodium yoeliiof rodents andPlasmodium falciparumof man. Mitochondria of the former parasite are cristate whereas those of the latter are essentially acristate. Isolated mitochondria from both parasite species were heterogeneous with respect to size, shape, density of matrix staining and extent of internal structure. Respiratory assay, by reduction of exogenous cytochromec, showed NADH, α-glycerophosphate and succinate to be the substrates with the greatest potential for metabolism. Additionally, proline, dihydroorotate and glutamate (P. falciparumonly) were oxidized at low rates. A number of NAD+-linked substrates were not utilized. The NADH-dependent reduction of cytochromecwas insensitive to rotenone and antimycin A. Fumarate inhibited the NADH-dependent reduction of cytochromecand stimulated the oxidation of NADH, suggestive of an NADH–fumarate reductase pathway. Oxidation of either α-glycerophosphate or succinate was fully inhibited by standard mitochondrial electron transport inhibitors, including a number of Complex III inhibitors, although the concentrations required of such inhibitors (notably myxothiazol) were relatively high compared to mammalian mitochondria. Dithionite-reduced minus oxidized difference spectra indicated the presence of cytochromesaa3,b, candc1in mitochondria of both parasite species, but at a higher cytochrome to protein ratio inP. yoelii. Freshly isolated mitochondria from either species exhibited only low respiratory control ratios with α-glycerophosphate or succinate as substrates. The apparent absence of a respiratory chain ‘Site I’ in such mitochondria may mean that NADH–fumarate reductase serves to reoxidize mitochondrial NADH.
Activated macrophages in highly irradiated cercariae-induced immunity toSchistosoma japonicumin rats
Authors: Xu C. , Xu S.
Published: June 2009

The results of studies on the schistosomulicidal activity of activated peritoneal and alveolar macrophages (pMø and aMø) from rats immunized with highly irradiated (50 krad.)Schistosoma japonicumcercariae are reported. The authors have examined the activation of these macrophages in terms of spreading, adhesion and ingestion of sheep erythrocytes and pinocytosis of horse-radish peroxidase. Using three criteria, peritoneal macrophages and alveolar macrophages from immunized rats and from rats intraperitoneally injected with BCG were significantly more active than those from normal rats or rats stimulated with 10% proteose-peptone or 1% sodium thioglycolate. A significantly higher percentage of adhesion and ingestion was obtained with the sheep erythrocytes that were co-opsonized by heat-inactivated rat anti-sheep erythrocyte serum and fresh normal rat serum. Schistosomulicidal effects were observed with macrophages from irradiated cercariae-immunized rats in two activation systems:in vitroactivation in the presence of macrophage-activating factor (MAF), andin vivoactivation by the intraperitoneal challenge with sonicated cercarial antigens.
Trichobilharzia ocellata: influence of infection on the fecundity of its intermediate snail host Lymnaea stagnalis and cercarial induction of the release of schistosomin, a snail neuropeptide antagonizing female gonadotropic hormones
Authors: Schallig H. D. F. H. , Sassen M. J. M. , Hordijk P. L. , De Jong-Brink M.
Published: June 2009

Subadult and adult specimens of the pond snail Lymnaea stagnalis were infected with the schistosome Trichobilharzia ocellata. Egg production and growth of the snails were monitored over an 8-week period post-infection (p.i.). Snail haemolymph was collected and analysed for the presence of schistosomin, a neuropeptide which antagonizes the action of the snails' female gonadotropic hormones. Snails infected as subadults showed an increase in fecundity during the first 4 weeks p.i. compared with non-infected controls. The possibility is discussed that this increase is caused by an accelerated maturation of the female sex organs due to elevated levels of Dorsal Body Hormone, a female gonadotropic hormone. No difference in fecundity was found between snails infected as adults and control snails during the first 4 weeks p.i. Snails infected as subadults and as adults showed a decrease in fecundity from week 5 p.i. and onwards. This decrease coincided with the appearance of schistosomin in the haemolymph of the snails and with that of differentiating cercariae in the daughter sporocysts. Cercariae are probably involved in the induction of schistosomin release from the snails' CNS into the haemolymph. Snails infected as subadults or as adults grew at approximately the same rate as uninfected snails.
Spermatogenesis and the fine structure of the mature spermatozoon of the liver fluke, Fasciola hepatica (Trematoda: Digenea)
Authors: Stitt A. W. , Fairweather I.
Published: June 2009

Spermatogenesis and the fine structure of the mature spermatozoon of Fasciola hepatica have been studied by transmission electron microscopy. The primary spermatogonia display a typical gonial morphology and occupy the periphery of the testis. They undergo 3 mitotic divisions to give rise to 8 primary spermatocytes forming a rosette of cells connected to a central cytophore. The primary spermatocytes undergo 2 meiotic divisions, resulting in 32 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by the formation of the zone of differentiation which contains 2 basal bodies and a further centriole derivative, the central body. The zone extends away from the spermatid cell to form the median process; into this migrates the differentiated and elongate nucleus. Simultaneously, 2 axonemes develop from the basal bodies. During development, they rotate through 90° to extend parallel to the median process. The migration of the nucleus to the distal end of the median process coincides with the fusion of the axonemes to the latter to form a monopartite spermatozoon. The mature spermatozoon possesses 2 axonemes of the 9 + ‘1’ pattern typical of parasitic platyhelminths, 2 elongate mitochondria and a variable array of peripheral microtubules. The nuclear region of the spermatozoon is immotile. The value of sperm ultrastructure as a taxonomic tool in platyhelminth phylogeny is discussed.