bluuebunny/crossref_metadata_2025 huggingface dataset:
L-Glutamine: an amino acid required for maintenance of the tegumental membrane potential of Schistosoma mansoni
Authors: Lane Carolyn A. , Pax R. A. , Bennett J. L.
Published: June 2009

The tegumental membrane potential (–63±2·9 mV) of adult male Schistosoma mansoni in RPMI-1640 is significantly depolarized (–26±7·3 mV) when the parasite is incubated in inorganic media (Hank's Balanced Saline or RPMI-1640 without organic constituents). Of 9 amino acids (L-glutamine, D-glutamine, L-arginine, L-proline, L-aspartate, L-glutamate, L-asparagine, L-isoleucine and L-methionine) L-glutamine alone is sufficient to repolarize the membrane potential to a value (–56±4·5 mV) not significantly different from that found in RPMI-1640. Repolarization by glutamine is dose-dependent, with significant effects obtained as low as 0·10 mM. The concentration of phosphate in the medium also significantly alters the membrane potential. Physiological levels of phosphate (5·6 mM) are necessary in conjunction with L-glutamine to obtain the full repolarization of the membrane potential. In the absence of organic constituents, the membrane potential is strongly dependent on the external medium pH. When L-glutamine is present in the medium, the membrane potential becomes virtually independent of the external pH.
Schistosoma mansoni: structural damage and tegumental repair after in vivo treatment with praziquantel
Authors: Shaw M. K. , Erasmus D. A.
Published: June 2009

The long-term, in vivo effects of a single, subcurative dose (200 mg/kg body weight of mouse) of praziquantel on the structure of adult Schistosoma mansoni and on the process and speed of tegumental repair are described. In both male and female worms praziquantel caused often extensive damage to the tegument, in the form of surface blebbings, swellings and lesions, and vacuolization and disruption of the subtegumental tissues. Repair of the drug-induced tegumental damage occurred slowly with partial and, more rarely, complete repair only being seen after 65 days post-treatment (p.t.), although signs of damage were still observed, particularly in male worms, at 100 days p.t. In contrast, repair of damage to the subtegumental/parenchymal tissues including the tegumental perikarya occurred relatively quickly, with the majority of worms examined appearing normal by 8–12 days p.t. The possible role(s) of the host immune response in relation to the speed of tegumental repair in vivo is discussed.
Identification and characterization of a polysaccharide-containing antigen fromSchistosoma mansonieggs which cross-reacts with the surface of schistosomula
Authors: Dunne D. W. , Bickle Q. D.
Published: June 2009

Antisera were produced by immunizing rabbits with either a trichloroacetic acid-soluble fraction, or a high molecular weight (Mr) fraction ofSchistosoma mansoniSEA (a salinesoluble fraction of homogenized egg). Both of these sera reacted monospecifically in immunoelectrophoresis against unfractionated SEA, recognizing a cathodally migrating antigen. This antigen had been identified previously as being responded to byS. mansoni-infected mouse sera, and has been designated K3(Kappa 3). The rabbit antisera were used to partially characterize antigen K3as havingMrin the range > 750 – 70 K, and being resistant to boiling, resistant to the action of proteases, but sensitive to periodate. It partially binds to Concanavalin A. In addition to SEA, the antigen was present in homogenized cercariae and schistosomula, but not adult worms, and it was also present in detergent extracts of intact cercariae and schistosomula. Using an antibody-dependent cell adherence assay, anti-K3serum was found to react with the surface of live cercariae and with the surface of schistosomula recovered from the skin of mice infected up to 48 h previously. Anti-K3serum also reacted with the surface ofS. bovis, S. haematobiumand to a lesser extentS. japonicumschistosomula.
Vaccination of young lambs by means of a protein fraction extracted from adultHaemonchus contortus
Authors: Munn E. A. , Greenwood C. A. , Coadwell W. J.
Published: June 2009

Lambs aged 48–150 days which had been injected with extracts enriched in a functional antigen (contortin) obtained from adultHaemonchus contortusdeveloped specific circulating antibodies and were less susceptible to haemonchosis when challenged 1 month later with a single dose of 20000–25000 infective 3rd-stage larvae. Sera from 18 out of a total of 19 lambs injected with the extract contained precipitating antibodies to 2–5 components of the extract. None of these lambs died. The one extract-injected lamb which did not develop antibodies and 9 of the 13 lambs used as controls died of haemonchosis. The average weight of worms recovered was 1·45 g from the immune lambs and 5·72 g from the non-immune lambs.
The effect of Trichostrongylus tenuis on the caecal mucosa of young, old and anthelmintic-treated wild red grouse, Lagopus lagopus scoticus
Authors: Watson H. , Lee D. L. , Hudson P. J.
Published: June 2009

The caecal mucosa of wild young and adult grouse infected naturally with Trichostrongylus tenuis was examined by means of scanning electron microscopy and compared with adult grouse which had been treated with an anthelmintic. The caecal mucosa of young red grouse with low worm burdens possessed longitudinal plicae and exhibited little damage. The caeca from adult grouse, most of which carried high worm burdens, showed a localized depression of plicae and atrophy and cell disruption in areas of nematode aggregation. Caeca from adult birds treated with an anthelmintic showed a similar caecal structure to lightly infected caeca from young birds. It is concluded that the normal functioning of the caeca is probably affected by heavy infections of T. tenuis.
Cultivation of Trypanosoma cruzi in irradiated muscle cells: improved synchronization and enhanced trypomastigote production
Authors: Schmatz D. M. , Murray P. K.
Published: June 2009

Since the in vitro production of trypomastigote stages of Trypanosoma cruzi in cell culture is frequently limited by (1) host cell overgrowth and (2) by the unequal redistribution of parasites after cell division resulting in asynchronous release of trypomastigotes, a culture system was devised in which host cell mitosis was inhibited by irradiation prior to parasite infection. L-6 rat myoblast cells when exposed to 3000 rad. of gamma radiation lost their ability to divide but remained susceptible to infection with, and capable of supporting the intracellular growth of, T. cruzi. Using this approach it proved possible to have virtually 100% of cells infected and achieve much better synchronization of trypomastigote release than with conventional culture systems. Additionally, the total number of parasites provided approached 1 × 109 trypomastigotes/ 150 cm2 flask, a significant increase over other culture systems. Preliminary studies with Plasmodium fallax and Eimeria tenella indicate that irradiated host cells may be utilized to advantage for the cultivation of other intracellular protozoa.
Characterization of excretory-secretory antigens ofFasciola hepatica
Authors: Irving D. O. , Howell M. J.
Published: June 2009

Twenty-one day oldFasciola hepaticawere recovered from the livers of infected mice and cultured for 5–7 days in a serum-free medium containing either [C]leucine, [C]isoleucine or [S]methionine, or in a medium containing [C]leucine and serum from a sheep vaccinated with excretory– secretory (ES) antigens of juvenileF. hepatica. All three labelled amino acids were incorporated into fluke proteins. Labelled proteins also appeared in the culture medium. Three major polypeptides detected in the culture media had apparent molecular weights of 26000, 24000 and 23000. All were immunoprecipitated from [C]leucine-labelled culture medium using antisera against fluke somatic antigens raised in rabbits or from sheep vaccinated with ES antigens of juvenileF. hepatica. A polypeptide of molecular weight 27 000 was also prominent in the culture medium when [C]isoleucine was used. This polypeptide was present as a minor component when [C]leucine and [S]methionine were included in the culture media; it did not appear to be immunoprecipitated by the above antisera from [C]leucine-labelled culture medium. In the presence of serum from vaccinated sheep, the ES antigens formed immune complexes which contained the polypeptides mentioned above, together with several higher molecular weight polypeptides. Additionally, a number of minor bands of varying molecular weight were present. After micro-Ouchterlony gel immunodiffusion, 2 precipitin lines formed between the labelled ES antigens and antisera. Electrophoresis of these indicated that the 23000, 24000 and 26000 Dalton labelled polypeptides were present in each. The higher molecular weight and the 27000 Dalton labelled polypeptides were also present in one of the lines.
Eimeria mitis: a comparison of the endogenous developmental stages of a line selected for early maturation and the parent strain
Authors: McDonald V. , Shirley M. W.
Published: June 2009

The endogenous development of the Houghton (H) strain of Eimeria mitis (= mivati) was compared with the life-cycle of a precocious (HP) line derived from the H strain. In both parasites 4 generations of schizonts which developed in epithelial cells were observed: the 1st and 2nd were found in the crypts and the 3rd and 4th in the villi. Gametocytes and zygotes occupied epithelial cells at the tips of the villi. The onset of gametogony normally coincided with the maturation of 4th-generation schizonts. The infection was confined initially to an area of the gut extending from the jejunum to the ileo-caecal junction but 3rd-generation merozoites and subsequent stages were also found in the caeca and rectum. The life-cycle of the precocious line was shorter than that of the parent strain. Gametocytes appeared to develop from 3rd-generation as well as from 4th-generation merozoites. Also, sporozoites of the precocious line transformed to trophozoites before those of the parent strain. First-generation schizonts of the HP line tended to be smaller and to contain fewer merozoites than those of the H strain. The differences between the life-cycles of the two parasites account for the lower reproductive potential of the precocious line.
Isoelectric focusing of general protein and specific enzymes from pathotypes of Globodera rostochiensis and G. pallida
Authors: Fox P. C. , Atkinson H. J.
Published: June 2009

Variations in the general protein and 40 enzymes of the 8 European pathotypes of the potato cyst nematode Globodera rostochiensis and G. pallida have been examined by isoelectric focusing (IEF) and cluster analysis. Differences in the protein patterns were observed and the presence of a major band at pH 8·0 allowed the two species to be discriminated. Extra isozymed of peptidase (EC 3.4. 11.*) and esterase (EC 3. 1. 1. 1) were also found in G. rostochiensis. Intra-species variation was seen within G. rostochiensis for superoxide dismutase (EC 1. 15. 1. 1) and within G. pallida for phosphoglucomutase (EC 2. 7. 5. 1) and glucose phosphate isomerase (EC 5. 3. 1. 9). The results suggest that the two species are very similar and the prospect for recognizing their pathotypes by IEF is discussed.
Determination of nuclear DNA of five Eucoccidian parasites, Isospora (Toxoplasma) gondii, Sarcocystis cruzi, Eimeria tenella, E. acervulina and Plasmodium berghei, with special reference to gamontogenesis and meiosis in I. (T.) gondii
Authors: Cornelissen A. W. C. A. , Overdulve J. P. , Van Der Ploeg M.
Published: June 2009

DNA contents of individual stages of Isospora (Toxoplasma) gondii and other Eucoccida were measured after Feulgen-pararosaniline (SO2) staining either by direct microfluorometry or by scanning of microphotographic negatives. Frequency distributions were analysed using a computer program based on a mathematical model describing cell division. All stages of I. (T.) gondii, except fertilized macrogametes (2c), contained a haploid amount of DNA (1c), indicating that meiosis in I. (T.) gondii occurs during sporogony. Microgametes possessed 3·3% DNA in excess, presumably mitochondrial DNA. Nuclei of M2-and M3-merozoites differed in two characteristics: a small but distinct nucleolus was observed in almost 50% of the M2-merozoites but in none of the M3-merozoites; all M2 merozoites were strictly haploid, while all M3-merozoites were synthesizing DNA (17% above the haploid value). It may be concluded that all M2- and M3-merozoites are already sexually differentiated, i.e. are macro- and microgamontoblasts, respectively. DNA synthesis necessary for the development of the microgamont starts already in the microgamontoblast stage (M3-merozoite). M2-merozoites macrogametes, synthesize 11% extra DNA before fertilization, (after fertilization an extra amount of 12% of the diploid value was found), probably by amplification of genes for proteins which are needed for rapid maturation and later sporogony. Essentially parallel results have been found in Eimeria tenella and in crescent cystozoites of Sarcocystis cruzi. Absolute DNA values in representatives of the Eucoccida have been estimated as follows (10−15 g): I. (T.) gondii, 96; E. tenella and E. acervulina, both 75; S. cruzi, 216; Plasmodium berghei, 27. The value of the estimation of total haploid amounts as a tool in taxonomy of Eucoccida is discussed.
Characterization of the exposed carbohydrates on the surface membrane of adultSchistosoma mansoniby analysis of lectin binding
Authors: Simpson A. J. G. , Smithers S. R.
Published: June 2009

The surface architecture of adult maleSchistosoma mansoniwas explored using a range of lectins with differing carbohydrate specificities. Highest specific binding was achieved with concanavalin A and the agglutinin of molecular weight 60000 fromRicinus communis; the binding of wheat germ agglutinin was mostly non-specific. Small amounts of peanut agglutinin and soybean agglutinin binding were observed and the binding of these lectins was increased by pre-treating the parasite with neuraminidase. The fucose binding protein ofLotus tetragonolobusfailed to bind. These results indicate that mannose and/or glucose, galactose,N-acetyl-glucosamine,N-acetyl-galactosamine and sialic acid are exposed on the surface of the adult male schistosome.
Growth, development and pairing of Leucochloridiomorpha constantiae (Trematoda) metacercariae on the chorio-allantois of chick embryos cultivated in vitro
Authors: Fried B. , Fine R. H. , Felter Barbara L.
Published: June 2009

A simple in vitro technique was devised to culture chick embryos in Petri dishes from the 4th to the 21st day of incubation. Leucochloridiomorpha constantiae (Trematoda) metacercariae were placed either singly or multiply (5/embryo) on the chorio-allantois of in vitro grown embryos on day 7 and were removed on day 14. Growth and development studies were also made on worms grown singly or multiply (5/chick) in the bursa of Fabricius of the domestic chick. Worms grown singly or multiply in embryos were sexually mature, although eggs from these worms were abnormal when compared with eggs from worms recovered from chicks. The mean body area of worms from chicks was 2–3 times greater than that of worms from embryos. The mean body area of single worms from embryos was significantly larger than that of worms grown multiply in this site. However, the mean body area of multiple worms from the chick was significantly larger than that of single worms from this site. Worm pairs or clusters were seen in all embryos with the multiple infections.
Transmission ofSchistosoma mansonifrom man to snail: experimental studies of miracidial survival and infectivity in relation to larval age, water temperature, host size and host age
Authors: Anderson R. M. , Mercer J. G. , Wilson R. A. , Carter N. P.
Published: June 2009

We report the results of experimental work on (a) the influence of temperature on the age-dependent survival and infectivity of the mira-cidia ofSchistosoma mansoniand (b) the relationship between snail age, snail size and susceptibility to infection. The death rate of miracidia declined exponentially with age where life-expectancy was maximal (approximately 16 h) at 15 °C. Infectivity also declined rapidly with larval age but, in contrast to larval survival, the rate of infection was at a maximum at 25 °C. Snail susceptibility was shown to be more closely correlated with host size rather than host age. Susceptibility declined exponentially with increased host size. Size-dependent susceptibility was shown to generate concave age-prevalence curves for infection within snail populations, where the maximum prevalence is generated in snails of intermediary age. Simple mathematical models are developed to aid estimation of larval survival and infection rates and experimental results are discussed in relation to the overall transmission success of the parasite from man to snail.
Population distribution of Ochoterenella digiticauda (Nematoda: Onchocercidae) and Mesocoelium monas (Digenea: Brachycoeliidae) in naturally infected Bufo marinus (Amphibia: Bufonidae) from Jamaica
Authors: Wong M. S. , Bundy D. A. P.
Published: June 2009

The worm burden distributions of a macrofilarial nematode, Ochoterenella digiticauda, and a gastroenteric digenean, Mesocoelium monas, were examined in a naturally infected population of Bufo marinus from Jamaica. Both parasite species had over-dispersed distributions which were well described by the negative binomial probability model (k = 0·35 for 0. digiticauda; and k = 0·59 for M. monas). The intensity distributions of the two parasites were uncorrelated: there was no significant association between the intensity (whether absolute or relative) of infection of either parasite in individual hosts. It is suggested that different, and parasite species-specific, factors of the host interaction are involved in generating the separate distributions of the two parasite species.
Low temperature preservation ofPlasmodiumspp
Authors: Mutetwa S. M. , James E. R.
Published: June 2009

Interest in the long-term low temperature preservation of malaria parasites was initiated by Coggeshall's (1939) demonstration that the intra-erythrocytic stages could survive storage at −76°C for 70 days. Numerous studies have subsequently been published in which a variety of techniques have been used. In addition, several reviews have included sections on the cryopreservation of malaria, the most recent being by James (1980), Leef, Hollingdale, & Beaudoin (1981), Nguyen-Dinh, Chemangey-Masaba, Spencer, Campbell, Chin & Collins (1981) and a WHO memorandum (1981). Most of these reports and reviews have dealt with the problems of cryopreserving malaria parasites from a parasitological viewpoint. In an attempt to provide a cryobiologically orientated review of value both to cryobiologists and practicing parasitologists the published technical reports have been summarized in chronological order in Tables 1 and 2, and the important cryobiological parameters are discussed.
Immune response toTrichinellaepitopes: the antiphosphorylcholine plaque-forming cell response during the biological cycle
Authors: Ubeira F. M. , Leiro J. , Santamarina M. T. , Villa T. G. , Sanmartín-Durán M. L.
Published: June 2009

Phosphorylcholine (PC), an immunodominant component of the cell wall of certain bacteria, fungi and nematodes, is known to induce low anti-PC antibody levels during natural infection byTrichinella spiralis. This article reports a study in which spleen cells from BCF1 mice infected withTrichinellasp. larvae were found to produce large numbers of direct haemolytic plaques in response to PC conjugated to sheep red blood cells (SRBC) after muscle-encysted larvae had been killed by treatment with mebendazole. Inhibition of the response by PC-chloride, immunodiffusion and immunoelectrophoretic studies with the anti-PC IgA (TEPC-15) and anti-idiotype T15 serum assays showed the plaque-forming cell (PFC) response to be specific for PC. The absence of haemolytic plaques when unconjugated SRBC or TNP-SRBC were used as indicator cells ruled out involvement of a polyclonal response. Greatest anti-PC PFC response was found to be associated with a microsomal fraction designated FCpl, a particulate fraction behaving as a thymus-dependent antigen. The FCpl fractions from all four strains ofTrichinellaemployed induced anti-PC PFC responses when injected into mice. These results suggest that FCpl is a suitable antigen for use in detailed studies of immune responses toTrichinellaand related parasites.
The pattern of infestation of the beach-hopper amphipod Orchestoidea corniculata, by a parasitic mite
Authors: Kitron Uriel D.
Published: June 2009

The frequency distribution of an ectoparasitic mite, Gammaridacarus orchestoideae, on its amphipod host, Orchestoidea corniculata, was found to differ significantly from random for all monthly samples taken between October 1977 and October 1978. The negative binomial distribution provided a good fit to these aggregated distributions. The degree of aggregation was negatively correlated with the prevalence of infestation. Prevalence and intensity were highest in the winter, when the degree of aggregation was lowest, and vice-versa in the late summer. This seasonal pattern can be explained through changes in size and density of the host population, which are associated with changes in the size of the habitat of the hosts. Within each sample the host population was highly heterogeneous with regard to infestation by mites. Females carried heavier loads of mites than did males. Both prevalence and intensity were low in the post-moult stages of the moult cycle. Reproductive females showed lower prevalence and intensity of infestation than did either non-reproductive females or males. Analysis of the regression analysis of ‘mean crowding’ on mean density also indicated that aggregation stemmed from a non-random distribution of individual parasites, rather than from clumping of the infective stages of the parasite. Heterogeneity of the host population is suggested as an important cause of the aggregated distribution of the parasite population.
The survival of the cercariae of Schistosoma mansoni in relation to water temperature and glycogen utilization
Authors: Ruth Lawson J. , Wilson R. A.
Published: June 2009

Survival curves for cercariae of Schistosoma mansoni maintained at different temperatures were determined. Between 15 and 35 °C the curves were of reverse sigmoid form and the probit transformation gave a statistically good fit. The slope of the regression lines fitted to the probit transformations increased exponentially as the temperature rose. Above 35 °C heat intolerance became important and increased exponentially as the temperature rose. Below 15 °C, cold intolerance caused an initial high level of mortality followed by an extended period with insignificant mortality. The glycogen content of whole cercariae and separated cercarial bodies and tails was measured during ageing. The glycogen content of whole cercariae declined exponentially during ageing. This was a product of exponential decreases in the glycogen content of both the body and the tail of the organism. The cercarial tail was shown to contain slightly over half of the total glycogen content. The rate of glycogen use was higher in the tail than in the body. A computer simulation model was used to demonstrate that the observed exponential use of glycogen could generate survival curves similar to those observed experimentally.
Nematode egg-shells
Authors: Wharton David
Published: June 2009

The transmission of parasites often involves a high mortality of free-living stages in the environment outside the host. This may be offset by a high biotic potential. In addition, adaptations of nematode eggs and larvae that ensure their survival or increase their chances of infecting a host will reduce the potential wastage rate. Increasing transmission will have an effect equivalent to increasing the fecundity of the parasite and, energetically, may be the more favourable strategy.
Parasite-mediated reductions in the survival and reproduction of the backswimmer Buenoa scimitra (Hemiptera: Notonectidae)
Authors: Lanciani Carmine A.
Published: June 2009

The effect of the parasitic water mite Hydrachna virella on its host Buenoa scimitra was investigated using laboratory experiments. The mite parasitizes all but the first instar of the host. Survival rates were found to be greater among unparasitized than parasitized individuals of these instars. Instantaneous death rates were observed to be linear functions of the number of mites supported/host. The mite's effect on the host's death rate appeared to be directly related to the size of the engorged mite compared to the size of the host; greater relative sizes were associated with greater impacts. Unparasitized females oviposited significantly more eggs than parasitized females, and the instantaneous birth rate of the host was observed to be a non-linear function of mite load.
Intestinal helminths of man: the interpretation of egg counts
Authors: Hall Andrew
Published: June 2009

Of the 39 most common helminth parasites of man listed by Peters & Gilles (1977), 30 may be detected and often diagnosed by finding their eggs or larvae in the faeces of infected people. The preferred habitat of many of these helminths is the alimentary tract itself and the continual flow of material through the food tube provides a simple, passive and reliable means of transport and eventual exit from the host for the reproductive stages of a worm. Helminth eggs are generally less than 150 μm in diameter and although individually comprise a small material investment by the adult worm in the propagation of the species, the chances of infecting a host are so slim (though this may be a teleological inference) that adult worms are often highly fecund: a female Ascaris lumbricoides is estimated to release daily into the intestine approximately 200,000 eggs (WHO, 1967). Yet numbers should not always be equated with great substance or bulk – an equally important determinant of the chances of finding an egg in faeces: assuming a spherical diameter of 60 μm and a specific gravity of 1·2 (Sawitz, 1942) then a female Ascaris is estimated to produce only about 25 mg of eggs each day, which is 0·01% of a moderate daily output of 250 g of faeces.
Morphological effects of arprinocid on developmental stages ofEimeria tenellaandE. brunetti
Authors: Ball S. J. , Pittilo R. M. , Norton C. C. , Joyner L. P.
Published: June 2009

Medication of chicks with 70p.p.m. arprinoeid in the food, starting 2 days prior to inoculation withEimeria tenella, resulted in decreased oocyst production and oocyst sporulation. The main morphological alteration seen during the development of the second-generation schizont was a reduction in the number of second-generation merozoites due to incomplete merogony, resulting in large masses of vacuolated residual cytoplasm. In places around the developing macrogamete the integrity of the parasitophorous vacuole was lost by either the host cell limiting membrane making contact with the parasite pellicle, or the disruption of one or both of these surfaces apparently brought about by the intervention of the host cell mitochondria. Thirty p.p.m. arprinocid reduced sporulation of the oocysts ofE. brunettiand caused enlargement of the perinuclear space in the late merozoites and swelling of the endoplasmic reticulum around wall-forming bodies II.
Changes in the surface antigen profile ofSchistosoma mansoniduring maturation from cercaria to adult worm
Authors: Payares Gilberto , McLaren Diane J. , Evans W. H. , Smithers S. R.
Published: June 2009

Antigenic proteins on the surfaces of different developmental stages ofSchistosoma mansoniwere radio-iodinated by the lodogen-catalysed method and identified by immunoprecipitation with a panel of antisera. The sera comprised specific immune serum from mice harbouring a chronic schistosome infection or vaccinated with γ-irradiated cercariae; serum from rabbits immunized with adult schistosome tegumental outer membranes or a partially purified Mr32K glycoprotein from adult worm membranes; and a monoclonal antibody recognizing an Mr20 K antigen on the surface of schistosomula. The Mr38–32 K glycoproteins were the major antigens identified in surface-labelled cercariae and their probable association with the glycocalyx is discussed. Schistosomula transformed from cercariae either mechanically or by penetration of host skinin vitro, expressed a similar pattern of surface antigens to that identified for cercariae, but low molecular weight antigens of Mr20, 17 and 15 K were also detected. The Mr38–32 K glycoproteins, although present on newly transformed schistoso mula, were progressively replaced with time, by a single dominant glycoprotein (Mr32 K) expressing identical epitopes to those on the Mr 38–32 K complex. Moreover, the data confirm that the Mr32 K glycoprotein persists on the tegument afterin vivomaturation and is conserved, together with Mr20 and 15 K antigens, through to the adult stage. New antigens (Mr97 and 25 K) were also detected duringin vivomaturation and were present in late-stage schistosomes recovered from infected hosts. In addition, the enzyme alkaline phosphatase is expressed on the surfaces of 3-week-old liver worms as a dominant antigen (Mr65 K); this feature may be related to nutritional and/or physiological processes in the tegument of this metabolically active stage of development.
Isolation and antigen analysis of surface tegument membranes from schistosomula ofSchistosoma mansoni
Authors: Taylor D. W. , Wells Pamela Z.
Published: June 2009

The outer tegument membranes ofSchistosoma mansonischistosomula have been removed by mechanical disruption in a hypotonic salt solution and partially purified by differential and sucrose density gradient centrifugation. Fractionation was monitored by measuring increase in specific activity of bound [125I] wheat-germ agglutinin (WGA), alkaline phosphatase and calcium-stimulated ATPase. Two-dimensional IEF/SDS polyacrylamide gel electrophoresis was used to analyse the peptide composition of the isolated membranes and to compare and contrast with lactoperoxidase/glucose oxidase surface labelled peptides. At least 35 surface-labelled peptides were resolved on the two-dimensional maps: all were also present in the membrane material recovered from the sucrose gradient. Western blot analysis demonstrated a marked heterogeneity in the antibody response of infected human patients to individual membrane antigens. The antigenic profile of membranes isolated from cercariae, 18 and 96 h schistosomula were compared using Western blots: some minor differences were observed between the three preparations.
The ultrastructure of the pseudohaptoral squamodiscs of Diplectanum aequans (Monogenea)
Authors: Shaw M. K.
Published: June 2009

The ultrastructure of the pseudohaptoral squamodiscs of the monogenean Diplectanum aequans is described. The most prominent feature of the squamodisc is the presence of epidermally-embedded spines which are covered by the outer epidermal membrane. These spines, which are ‘hollow’, are composed of a moderately electron-dense material with denser fibrils embedded within it. The squamodisc epidermis is similar in appearance to the haptor epidermis, with the exception of the epidermis ‘inside’ the spines. Here the epidermis contains free ribosomes and stacks of alternating electron-lucent/electron-dense, membrane-bound sacs. The arrangement of the musculature of the spines is described. The free, prehensile, edges of the squamodiscs contain numerous radially orientated nerves, some of which are assumed to be mechano-receptors.
The establishment and population biology of the eye-fluke Tylodelphys podicipina (Digenea: Diplostomatidae) in perch
Authors: Kennedy C. R.
Published: June 2009

The introduction, establishment and subsequent history of a population of the eye-fluke Tylodelphys podicipina in perch in a small lake was studied over a period of 2 years. The introduction was a natural, chance colonization, and within 2 years of its first appearance the parasite was infecting 100% of the 0 + perch. Its dispersion within the perch population was initially random and fitted a Poisson model, but subsequently it became over-dispersed. Infection of fish took place only in or about June and only young of the year fish were susceptible. Fish were infected on one occasion only, shortly after birth, and there was no subsequent re-infection or mortality within the eye. The parasites lived for at least 2 years and there was no evidence of parasite-induced host mortality. Infection levels are thus an indication of the recruitment level in the year in which the fish were born. T. podicipina therefore differs from all other species of eye-flukes, which accumulate in fish throughout their life, but this infection strategy facilitates transmission of the parasites to their definitive host. Lower infection levels in older fish here and in other localities are considered to be due to the parasite being a recent introduction to the British fauna, and to its still being in the expansion phase of colonization in all localities.
Nematospiroides dubius: the course of primary, secondary and tertiary infections in high and low responder Biozzi mice
Authors: Jenkins D. C. , Carrington Trudi S.
Published: June 2009

Biozzi mice of Selections 1 and 3, each exhibiting either high- or low- antibody responses to a wide range of antigens, were exposed to primary, secondary and tertiary infections of the nematode, Nematospiroides dubius. The course of these infections was followed by monitoring egg output and by examination of the worm burdens on the 14th day after each exposure to the parasite. When exposed to a primary infection, high and low responders were equally susceptible to the parasite, and the egg production of the infections was similar in all groups. However, when the mice were exposed to a 2nd infection of N. dubius, marked differences in the susceptibility of the hosts were seen. The high-responder mice of both Selections 1 and 3 were significantly more resistant to infection, far less adult worms being found in these. Resistance to a 3rd and final infection of the parasite was amplified appreciably in all groups but, again, the high-responder mice were significantly more resistant than the low responders. These results imply that host antibodies play an essential role in immunity to this parasite and that resistance cannot be attributed solely to non-specific macrophage activity or cell-mediated immune reactions, since the latter are equivalent in high and low lines and the macrophages of the Ab/L line of Selection 1 are hyperactive.
Recovery of parasites at different stages of migration following infection of rats withSchistosoma mansoni
Authors: Knopf P. M. , Mangold Beverly L. , Makari G. J.
Published: June 2009

The technique of tail amputation is utilized as a method for interrupting the migration process ofSchistosoma mansonischistosomula from the skin of Fischer rats infected by exposure of the tail to cercariae. The yields of schistosomula recovered from the lungs at different times post-infection are compared, using rats with or without tail amputation. Residence times of schistosomula in skin and lungs, as well as their transit time and efficiency of migration between these sites, are estimated. At least one-third of the infecting cercariae migrate from skin to lung in rats. Amputation of the tail on days 4 or 5 post-infection isolates a definable number of schistosomula in the lung and their migration to the portal circulation can be followed. The kinetics of this migration in rats and mice is compared and a significant difference is revealed.
Observations on the field transmission dynamics of Schistosoma mansoni and S. mattheei in southern Natal, South Africa
Authors: Donnelly Fiona A. , Appleton C. C.
Published: June 2009

Cercarial transmission of Schistosoma mansoni and S. mattheei was monitored in two small rivers near Durban, South Africa. The seasonal patterns recorded corresponded to those already documented for these parasites. Tn the case of S. mansoni, however, this was interrupted at the height of the transmission season. The reason for this was believed to be very low oxygen concentrations in the snail habitat due to unusually extensive growth of the plant Ludwigia stolonifera over the water. The failure of the spring rains, which would normally have flushed the system is seen as contributing to this phenomenon. Infection rates in the snail intermediate hosts were low ( > 10%). A preponderance of male worms of both schistosome species was noted.
Ovine hydatidosis: some immunological characteristics of the seronegative host
Authors: Judson D. G. , Dixon J. B. , Clarkson M. J. , Pritchard J.
Published: June 2009

The immune status of a group of sheep naturally infected with hydatid cysts was investigated. Low specific anti-hydatid antibody (Sab) titres and negative results in intradermal and leucocyte migration tests occurred in hosts with high hydatid antigen-stimulated lymphocyte transformation(LT). Total(non-specific) IgG was elevated in infected sheep and was positively correlated with LT. Circulating hydatid antigen (cAg) was detectable in some infected sheep, but not in all of those with low Sab. Relationships between eAg, Sab and immune complex levels suggest that most eAg is present in immune complexes.
The activity of drug combinations against established infections of rodent malaria
Authors: Hill J.
Published: June 2009

In the experiments reported here treatment (with a single dose or daily for 4 days) was delayed until 3 days after inoculation. Various combinations of M&B 35769, 2:4-diamino-5-[3(4–4′-chlorophenylphenoxy)propyl-l-oxy]-6-methylpyrimidine HC1, plus sulphadoxine, and of M&B 35769 plus dapsone, were examined and it was concluded that no universally ideal ratio of constituents in a combination is possible because the optimum ratio depends upon the activity of the constituents on their own and therefore varies from strain to strain. Activity was assessed on the 24th day after infection. M&B 35769 was markedly superior to pyrimethamine against all strains when the compounds were given on their own but, although it showed good potentiation with sulphadoxine and dapsone, much of its lead over pyrimethamine was lost in combination. M&B 36821 2–4-diamino-5-[3-(3,4′-dibromobiphenyl-4-oxy)-propyl-l-oxy]-6-methyl pyrimidine HC1, was more active than M&B 35769 against pyrimethamine- and cycloguanil-resistant strains but not against sensitive strains.
Fatty acid and cholesterol synthesis in mice infected with the tapewormHymenolepis microstoma
Authors: Rath E. A. , Walkey M.
Published: June 2009

Infection withHymenolepis microstomasignificantly affected the lipid metabolism of young male Balb/C mice. Infection increased the rates of hepatic fatty acid and cholesterol synthesis and cholesterol synthesis by the gut. Decreases were recorded in testicular fatty acid synthesis and in the weights of testes and white epididymal adipose tissue. Plasma glucose decreased rapidly during infection. The observed changes in lipogenesis could not be attributed to changes in food intake or body temperature. The changes are discussed in relation to nutritional interactions between host and parasite and the possible effects on host hormone levels. The presence of newly synthesized fatty acid inH. microstomais also reported.
Differences in biological characteristics of two strains of the cestode Hymenolepis diminuta
Authors: Kino H. , Kennedy C. R.
Published: June 2009

Biological characteristics of infectivity, growth rate and fecundity of Hymenolepis diminuta isolated from wild Rattus rattus in Japan were compared with parasites of Texas origin maintained for several generations in this and many other laboratories in laboratory bred Rattus norvegicus. The timing of development and maturation was similar in parasites from both sources, but the mean parasite dry weight was less and the mean egg production lower in Japanese parasites in both single and multiple infections. The differences persisted over 10 weeks in single infections, and were unaffected by rat strain. In all experiments there was much greater variation and heterogeneity in the biological characteristics of the Japanese parasites. It was concluded that the Texas parasites were better adapted to R. norvegicus and in the course of adaptation had become more homogeneous, and that the difference between the parasite strains had a complex genetic basis. Some Japanese parasites of the early isolated generations failed to produce normal eggs, but the proportion of these decreased in later generations. However, selected individual Japanese parasites whose egg production was equal to that of parasites of Texas origin did not produce offspring of larger mean size or higher mean fecundity, and heterogeneity of these characteristics was maintained. In the intermediate host, the mean number of cysticercoids of the Japanese isolate per beetle was higher than that of the Texas strain in Tribolium confusum but lower in Tenebrio molitor. The greater heterogeneity exhibited by Japanese parasites and the genetic basis of the strain difference are discussed with particular reference to geographical isolation, differences in definitive hosts and co-evolution of wild and laboratory host and parasite populations.
A mathematical model of the population biology ofOstertagia ostertagiin calves and yearlings
Authors: Grenfell B. T. , Smith G. , Anderson R. M.
Published: June 2009

A mathematical model of the population biology ofOstertagia ostertagiis described. The model assumes that the natural control and regulation of parasite numbers is mediated by four processes: the effect of climate on the development and survival of the free-living stages; changes in the rate of establishment of the infective larvae, and density-dependent variations in parasite survival and fecundity. The model is used to compare the course of the infection in two groups of calves. One group is assumed to have been reared under conditions typical of S.E. England and the other under conditions typical of Louisiana, USA. The more general behaviour of the model is discussed in the context of sensitivity analysis. The model is an excellent mimic of the epidemiology of bovine ostertagiasis. It can be used as a simple screening procedure to help determine which of many possible anthelmintic control strategies should be selected for more detailed examination in the field, and it provides a theoretical framework within which ideas concerning the epidemiology of parasitic gastro-enteritis can be assessed and refined.
Glucose phosphate isomerase isozymes as genetic markers for lines of Eimeria tenella
Authors: Nakamura T. , Konishi T. , Kawaguchi H. , Hayashi Y.
Published: June 2009

Two strains of Eimeria tenella with different decoquinate sensitivity and different glucose phosphate isomerase (GPI) isozymes were used in genetic recombination experiments: a line derived from a laboratory strain (NIAH) was decoquinate-resistant (DR) and had the isozyme GPI-9, while a field isolate (Iwate strain) was decoquinate-sensitive (DS) and had GPI-1. Coccidia-free chickens were orally inoculated with mixed oocysts of the two strains and parasites of the F1 generation were recovered. The F1 progeny showed both forms of the isozyme. Next, oocysts of the F1 progeny were passaged through chickens given the decoquinate-containing diet. The F2 progeny also had GPI-1 and GPI-9, indicating crossfertilization between the two strains. Six single oocysts were isolated from F2 progeny; 1 showed both phenotypes of GPI, 1 had GPI-1 and the remaining 4 lines had GPI-9. Analysis of the amount of GPI in recombinant oocysts suggested that the proliferation rate of the DR strain was slower than that of the DS strain. We concluded that GPI isozymes in E. tenella can serve as useful markers in experiments on chicken coccidia.
Sex differences and cross-immunity in DBA/2 mice infected withL. mexicanaandL. major
Authors: Alexander J.
Published: June 2009

Female DBA/2 mice were found to be highly resistant toLeishmania mexicanaand rarely developed lesions even when inoculated subcutaneously with high numbers (5 × 106) of amastigotes. Male DBA/2 mice, on the other hand, were much more susceptible to this parasite and often developed non-healing lesions even when inoculated subcutaneously with comparatively few (5 × 104) amastigotes. Conversely, although both male and female DBA/2 mice developed ulcerating lesions when inoculated subcutaneously withL. majoramastigotes, lesions invariably healed in males but did not heal in females. Male DBA/2 mice recovered fromL. majorinfection subsequently were found to be resistant to subcutaneous challenge withL. mexicana. Conversely female DBA/2 mice that had failed to develop lesions when infected withL. mexicanadeveloped lesions which healed following subcutaneous challenge withL. major. Thus there is bilateral cross-immunity betweenL. mexicanaandL. majorin DBA/2 mice which overrides differences in sex-determined susceptibility to both organisms.
Integrated control of ticks and tick-borne diseases of cattle in Africa
Authors: Young A. S. , Groocock C. M. , Kariuki D. P.
Published: June 2009

The problems caused by tick and tick-borne diseases for livestock particularly cattle on the African continent are described and discussed. The control of ticks and tick-borne diseases must receive high priority in Africa with regard to both research and control application because of their widespread distribution in areas of high livestock potential and productivity. The conventional methods of tick and tick-borne disease control are discussed and are found to be inadequate in the conditions prevailing in Africa. Methods of integrated control are suggested and discussed in light of recent development in control methods and those still under development. Any one of these methods may not be adequate to control the problem on its own but when several of the methods are combined an economic and robust integrated control is likely to result. Encouragement is given to attempt this approach in Africa to solve what must be the largest animal health problem of livestock remaining in the world.
The effects of cholinergic and serotoninergic drugs on motilityin vitroofHaplometra cylindracea(Trematoda: Digenea)
Authors: McKay D. M. , Halton D. W. , Allen J. M. , Fairweather I.
Published: June 2009

The spontaneous activity of the somatic muscle of the amphibian lung fluke,Haplometra cylindraceahas been recordedin vitro, using an isometric force transducer system. Normal movement consisted of a continuous series of regular contractions which were maintained for over 4 h. Acetylcholine (ACh) inhibited motility and at a concentration of 1 χ 10–3M induced a flaccid paralysis. A similar response occurred with the cholinomimetic drugs, carbachol and nicotine, although in these instances the inhibition was less easily reversed by washing with frog Ringer. The inhibitory effect of ACh was blocked by d-tubocurarine but not by atropine.
Soil-transmitted helminth infections in school children from Cocle Province, Republic of Panama
Authors: Robertson L. J. , Crompton D. W. T. , Walters D. E. , Nesheim M. C. , Sanjur D. , Walsh E. A.
Published: June 2009

A survey was carried out to determine values for the prevalence and intensity of infection of intestinal helminths in children living in Cocle Province, Republic of Panama. The data set consisted of the results of microscopic examinations (modified Kato Katz technique) of stool samples collected in November 1987 from 661 children attending primary schools in 4 communities in the province. The overall prevalences of Ascaris lumbricoides, hookworm and Trichuris trichiura infections were found to be 18·2, 12·0 and 27·5% respectively. There were significant differences between the infection prevalence values for children attending the different schools, but not with respect to age or sex. Positive associations were detected between particular pairs of infections and these were most evident when Trichuris trichiura was involved. The data revealed evidence of a positive association between siblings at one school only for each helminth infection.