bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal occurrence, sex ratio and site preference ofArgulus coregoniThorell (Crustacea: Branchiura) parasitic on cultured freshwater salmonids in Japan
Authors: Shimura S. 
Published: June 2009

SUMMARYAnalysis of the seasonal occurrence ofArgulus coregonionOncorhynchus masouandSalmo gairdneriindicates that the parasites overwinter as eggs and that there are 1 or 2 generations/year. Larvae which hatch from the overwintered eggs are abundant from May through July. Individuals hatched in May and June attain maturity and lay eggs in August. Larvae of the second generation are abundant in September, and they lay eggs in October–November which overwinter. Hatched larvae from overwintered eggs may mature in July and deposit overwintering eggs in September. The sex ratio ofA. coregoniis about 1:1.A. coregonishows an age-specific site preference onO. masou. Small parasites occur on almost all parts of the skin and fins, with slightly heavier concentrations on and around the pectoral and pelvic fins. Large parasites are found mainly on the skin around these fins.
Sexual processes in the kinetoplastida
Authors: Tait A. 
Published: June 2009

SUMMARYThe commonly held view that the kinetoplastida, and in particular trypanosomes, are asexual is largely derived from the principle that an organism is asexual until proved sexual. If the basis for this view is examined in detail, it largely arises from the lack of morphologically distinguishable gametes, the difficulties encountered in visualizing chromosomes and a few experiments, using drug-resistant stocks, in which no recombination between stocks could be demonstrated. While it is clear that these organisms are able to reproduce asexually, the existence of a sexual cycle was, until recently, an entirely open question. The early work strongly suggests that any sexual process (in the species examined extensively at the morphological level) does not involve classical well-differentiated gametes and so must involve fusion of morphologically very similar cells. These findings taken together with the inability to visualize chromosomes and thereby identify meiosis, mean that classical methods are unable to detect any sexual process even if it did occur. This review examines the evidence provided by the experimental approaches which have been applied recently to the question of kinetoplastid sexuality. These approaches include isoenzyme studies and the analysis of possible genetic exchange by the use of selective markers (e.g. drug resistance). The results which these techniques have produced make it clear that the kinetoplastid protozoans cannot be regarded as a totally asexual group of organisms.
Pattern and paradox in parasite reproduction
Authors: Calow P. 
Published: June 2009

SUMMARYParasites are more fecund than free-living relatives. The traditional explanation of this is that parasites have to compensate for massive mortality in the transmission phase of their life cycles, but there are neo-Darwinian problems with this interpretation. Similarly, parasites invest more resources in reproduction than free-living relatives but often live longer as adults, and yet negative correlations are expected between fecundity and longevity. These patterns and paradoxes are discussed within the context of a general life-cycle theory. The theory is also used to address questions concerning the influence of age-specific mortality on life-cycle patterns, the trade-off between gamete size and numbers, and the relative merits of gametic and non-gametic reproduction. Wherever possible, the theory is related to facts about parasites.
Experimental infections withCooperia oncophora(Railliet, 1918) in calves. Results of single infections with two graded dose levels of larvae
Authors: Borgsteede F. H. M. , Hendriks J. 
Published: June 2009

SUMMARYTwo experiments were carried out in which calves reared parasite-free were infected with a single dose of 3rd-stage larvae ofCooperia oncophora. In the first experiment the calves received 20000 or 200000 infective larvae and they were autopsied 28 or 56 days after the infection. In the second experiment the doses were the same but the animals were killed 14, 84 or 140 days after infection. If a dose of 20000 was given, clinical signs were never observed, while at a dose level of 200000 the weight gain was less on 56 and 84 days after the infection compared with the low-infected groups or the control animals. After 140 days the differences in weight gain were compensated. Faecal egg output was higher in the 200000 groups only in the first period of patency, thereafter the calves in the 20000 groups produced more. No obvious differences between the two infection levels were observed with regard to the haematological data. In the low-infected groups worm counts were only slightly lower when the results after 28 days were compared with those after 56 days. Also, the worm numbers after 14 days were almost equal to those after 84 days, while at 140 days 1 animal still had the same number, the other one had lost its worm burden. In the high-infected groups the worm loss was much quicker. After 28 days a great part of the population had already been lost. Obviously, at the 200000 level the reaction of the host against the parasite was much stronger. Adult worms were expelled at a higher rate than early 4th-larval stages. In the first experiment worm measurements revealed differences between the length of females, males and spicules of males, these being significantly longer in the low-infected groups. Analysis of the distribution of worms over the small intestine showed that in the low-infected groups worms were mainly restricted to the first 6 metres. In the high-infected groups the worm population was distributed more evenly over the whole small intestine.
Observations on coprophagy and the transmission ofHymenolepis nanainfections in mice
Authors: Ghazal A. M. , Avery R. A. 
Published: June 2009

SummaryYoung, previously uninfected white mice became infected withHymenolepis nanawhen exposed in small cages to parasite eggs which had been sprinkled in suspension onto the floor of their cage, or to faeces from mice with patent infections. The mean daily probabilities of infection for individual eggs under these two conditions were 2·9 × 10−6and 5·4 × 10−6respectively. If the mice were starved for 24 h prior to exposure to faeces, then the mean daily probability of infection increased to 2·6 × 10−4. These differences in transmission are interpreted as being due to differences in the extent of coprophagy; they are not due to any effect of starvation on the hatchability of eggs.
Acquired resistance of black mollies Poecilia latipinna to infection by Ichthyophthirius multifiliis
Authors: McCallum H. I. 
Published: June 2009

SUMMARYChanges in the response of black mollies Poecilia latipinna to infection with Ichthyophthirius multifiliis subsequent to single I. multifiliis infections were examined experimentally. Incomplete resistance to infection was established, the degree of which did not depend on the intensity of the initial infection. Resistance was maintained for longer periods, however, by those fish with higher initial levels of infection. Previous experience of infection by their hosts had a significant, though small, effect on the time for which trophozoites remained on the fish. The influence of these results on the population dynamics of the Ichthyophthirius-fish interaction is examined with the aid of simple mathematical models.
In vitro demonstration of in utero larval development in an oviparous parasitic nematode: Haemonchus contortus
Authors: Ayalew Liyew , Pearson Murphy Beverley E. 
Published: June 2009

SUMMARYThe life-cycle of Haemonchus contortus, a pathogenic stomach nematode of sheep, is typical of those of the other members of the superfamily Trichostrongyloides, all of which require a period of development outside the definitive host. Classically, gravid H. contortus, known as strictly oviparous, releases her eggs into the abomasal lumen. The eggs are passed out in the faeces in which they hatch into the 1st-stage larvae and then develop into the infective 3rd-stage larvae. We have developed a method to study the fate of eggs within gravid worms. Using this procedure, we have shown that H. contortus may also exhibit viviparity with apparently normal development from the egg to the 4th larval stage taking place within the gravid female maintained in vitro. On the basis of these observations we speculate that viviparity might occur in vivo with consequent autoinfections; if so, this might explain some puzzling clinical and epidemiological features of haemonchosis, as well as the incomplete efficacy of current control measures.
Studies on the life-cycle ofHimasthla militaris(Trematoda: Echinostomatidae): influence of temperature and salinity on the life-span of the miracidium and the infection of the first intermediate host,Hydrobia ventrosa
Authors: Vanoverschelde R. 
Published: June 2009

SUMMARYThe influence of temperature and salinity on miracidial longevity and miracidial infectivity of the digenean,Himasthla militaris, has been examined. At 14, 25 and 30 °C the half-life of the miracidia was 1200, 630 and 420 min respectively, and infection of the first intermediate host,Hydrobia ventrosa, only occurred at 25 and 30 °C, for both temperatures 52% became infected. In the range 2·1 to 34‰ (2·1, 4·2, 8·5, 17 and 34‰) the miracidia had a minimal and maximal half-life of 60 and 630 min in water with a salinity of 2·1 and 17‰ respectively, while the infection of the snail host was possible only in water with a salinity of 8·5 and 17‰.
Proteinases ofLeishmania mexicanaand other flagellate protozoa
Authors: Coombs G. H. 
Published: June 2009

SUMMARYThe amastigote form of the human pathogenLeishmania mexicanacontains high proteinase activity, some 20 times greater than that in the promastigote form and macrophages and appreciably higher than the activity in other flagellate protozoa. The main amastigote enzymes are soluble, whereas those of the promastigote are particulate, and have inhibitor sensitivities characteristic of cysteine proteinases. The very high soluble proteinase activity ofL. mexicanaamastigotes may be a primary factor in the survival and growth of this mammalian stage in its potentially degradative intracellular habitat.
The dynamics of infection of Tribolium confusum by Hymenolepis diminuta: the influence of exposure time and host density
Authors: Keymer Anne 
Published: June 2009

SUMMARYSurvival of Hymenolepis diminuta eggs (as measured by their infectivity to the intermediate host) was found to be age-dependent with an expected value of 11 days when the eggs were retained within the faecal pellet at 10 °C. The expected life-span of eggs under experimental conditions (i.e. extracted from faecal material and placed on filter paper at 30 °C) was estimated as 33 min. The mean parasite burden of populations of Tribolium exposed to known densities of H. diminuta eggs was found to rise to a plateau with increasing exposure time. The experimental results provided a method of estimating the instantaneous rate of parasite transmission: a value of 0·0004/egg/min/host/13 cm2 was obtained. The mean parasite burden of populations of T. confusum exposed to known densities of H. diminuta eggs was found to decrease exponentially with increasing host density. A second estimate of the instantaneous rate of parasite transmission of 0·004/egg/min/host/13 cm2 was obtained from the experimental results. No differences in susceptibility to infection between 2-week-old male and female beetles were found. A marked decrease, however, was apparent with increasing beetle age up to 14 weeks post-eclosion.
Schistosoma mansoni: a histological study of migration in the laboratory mouse
Authors: Wheater P.R. , Wilson R. A. 
Published: June 2009

SUMMARYQuantitative histological methods were applied in a study of the migratory route of schistosomula within the definitive mammal host. The observations are consistent with an entirely intravascular mode of migration in the direction of blood flow. They do not support a trans-diaphragm route. Schistosomula can be identified in low numbers in systemic organs, in the left side of the heart and in the venous compartment of the pulmonary circulation. They were not observed penetrating the diaphragm or the capsule of the liver. No histopathological evidence was found to suggest that the tissue responses of previously unexposed hosts affect migrating schistosomula at any stage during migration. These non-specific tissue responses were marked only in the skin phase of migration.
The mode of action of suramin on the filarial worm Brugia pahangi
Authors: Howells R. E. , Mendis A. M. , Bray P. G. 
Published: June 2009

SUMMARYThe mode of action of suramin upon Brugia pahangi has been investigated in vivo and in vitro. The drug was without effect on the glycolytic activity of worms in vitro at 2 × 10−4 M. The lack of effect was correlated with the failure of [14C]suramin to penetrate the worms in vitro. Suramin bound to the surface of worms in vitro presumably by virtue of its polyanionic nature. B. pahangi adults ingested [14C]suramin in vivo but no reduction in the rate of lactate production, of glucose utilization or in the rates of uptake of [14C]glucose, [14C]leucine or [14C]adenosine was observed in worms recovered from jirds between weeks 1 and 5 following 4 daily doses of suramin at 50 mg/kg given intraperitoneally. Worm death occurred between weeks 5 and 7 but this delayed drug effect was not the result of a progressive accumulation of suramin in the worms. Ultrastructural changes were observed in the intestinal epithelium of worms from suramin-treated jirds and parallel observations on worms exposed to Trypan blue in vivo suggest that both polyanionic compounds are restricted to the intestinal lumen of the worms. The evidence presented is consistent with the concept that, in B. pahangi, suramin acts at the surface of the intestinal epithelium and not by primarily inhibiting glucose catabolism or inhibiting phagosome and lysosome fusion as previously demonstrated for bloodstream trypanosomes and mammalian macrophages, respectively
Studies on the pathology of an avian trypanosome (T. bouffardi) infection in experimentally infected canaries
Authors: Molyneux D. H. , Cooper J. E. , Smith W. J. 
Published: June 2009

SUMMARYExperimental infections of canaries with an avian trypanosome, Trypanosoma bouffardi, isolated from West Africa demonstrated that these infections can cause pathological changes in tissues. Enlargement of the spleen coincided with peak parasitaemia but no other gross changes were observed. Histopathological examination of infected and control birds revealed focal myocarditis and lymphoid hyperplasia, in infected birds, which are consistent with trypanosome infection. Avian trypanosome infections are not usually regarded as pathogenic but our results suggest that pathological changes occur which are similar to those observed in mammals infected with salivarian trypanosomes
The enzymes of purine salvage inTrypanosoma cruzi, Trypanosoma bruceiandLeishmania mexicana
Authors: Davies Mary J. , Ross A. M. , Gutteridge W. E. 
Published: June 2009

SUMMARYWe have previously shown the presence of various purine salvage enzymes inTrypanosoma cruzi, including phosphoribosyltransferase, aminohydrolase, kinase, phosphorylase and hydrolase activities. We now report that a similar situation occurs inLeishmania mexicana amazonensisandTrypanosoma brucei brucei. In all three organisms we found higher levels of activity for the phosphoribosyltransferase enzymes than for the nucleoside kinases, suggesting a preference for the salvage of purine bases rather than nucleosides. Similarly, absence of inosine phosphorylase activity suggests that only one route for the salvage of hypoxanthine is available to the three organisms. The most striking difference was that whereasT. cruziandT. bruceipossessed adenosine aminohydrolase activity, this was not detected inL. mexicana; instead adenine amino-hydrolase activity was found. The overall similarity, as judged by the distribution of enzyme activities, of purine salvage in these three members of the kinetoplastida suggest a broad spectrum of activity for any inhibitor acting in this area; the plethora of alternative salvage pathways, however, suggests that in no case would such inhibition be cidal.
The co-occurrence of three species of Diorchis Clerc, 1903 (Cestoda: Hymenolepididae) in the European coot, Fulica atra L.
Authors: Pojmańska Teresa 
Published: June 2009

SummaryThe relationship between intensity and site of infection of Diorchis brevis, D. inflata and D. ransomi in Fulica atra from central Poland has been analysed; of 173 adult birds 152 (87·9%) were infected with one or more of these three species. From (1) the incidence of the three species (D. brevis, 59·5%; D. inflata, 69·9%; D. ransomi, 61·3%), (2) the high total incidence and high total intensity of infection (118·2 worms/bird) in hosts harbouring the three species concurrently and (3) the frequent co-occurrence of all three species in the same site in the host gut, it is concluded that there are no antagonistic interactions among these species. There are, however, some inter-dependencies between the number of parasites and the site occupied by particular species. In heavy infections there was a tendency to specific segregation and extension of the site of each species. This suggests the existence of inter- and intra-specific competition at higher densities of infection, regulating the spatial distribution of these parasites in the host gut.
The survival of desiccation by the free-living stages ofTrichostrongylus colubriformis(Nematoda: Trichostrongylidae)
Authors: Wharton D. A. 
Published: June 2009

SummaryThe survival of the free-living stages ofTrichostrongylus colubriformisunder defined conditions of temperature and relative humidity was investigated. The survival of embryonated eggs was poor at 0, 33 and 54·5 % relative humidity (rel. hum.) at 20 °C but hatching occurred from a proportion of eggs even after exposure for 104 days to 76 and 98% rel. hum. at 20 °C. Second-stage larvae were desiccation-susceptible and were killed within 6 h even at 98% rel. hum. and 20 °C. Infective larvae, dried separately or in clumps, survived prolonged exposure to desiccation at 33–98% rel. hum. and 20 °C with 50% survival times of 58–164 days. Clump formation did not enhance survival in this range. Infective larvae also survived exposure to vacuum desiccation with 50% survival times of 8·8 h in clumps and 4·5 h when dried separately. The infective larva thus readily survives desiccation and may prove a useful model for the study of anhydrobiosis.
The anti-neoplastic effect of trichinellosis in a syngeneic murine model
Authors: Pocock Dorothy , Meerovitch Eugene 
Published: June 2009

SummaryC57B1/6 male mice with chronic trichinellosis, and age-matched uninfected control mice, were inoculated with B16 melanoma cells. Tumour development was inhibited in the infected animals. In the infected tumour-bearing mice, the tumour induction intervals were longer and the tumour size was subsequently smaller than in the control mice. Moreover, when the number of tumour cells in the inoculum was less than that required to produce 100% tumour incidence in the uninfected mice (<1 × 104 cells), significantly more of the mice with an infection of 2 months duration remained tumour-free. These results were significant at the P<0·05 level.
Environmental sodium regulates cutaneous sugar transport in a digenean fluke
Authors: Uglem G. L. 
Published: June 2009

SUMMARYGlucose uptake was examined in adult specimens of Proterometra macrostoma (Trematoda: Digenea) recovered from the stomach (endoparasites) and gills (ectoparasites) of longear sunfish, Lepomis megalotis. The endoparasitic forms transported glucose directly through the external body surface by Na+-independent, facilitated diffusion, but the ectoparasites absorbed glucose by free diffusion alone. To determine how this transport function is regulated, cercariae were incubated in solutions having Na+ concentrations normally found in fish gut (50 mM) and in fresh water (0·5 mM). Glucose transport capacity was retained in 50 mM Na+, but disappeared in worms incubated for 1–3 days in 0·5 min Na+. Returning worms from the latter solution to one containing 50 mM Na+ fully restored glucose transport within a day. By contrast, incubation up to 5 days in 0·5 mM Na+ had no effect on glucose transport in endoparasitic adults of P. macrostoma and cercariae of P. edneyi. Thus, cutaneous sugar transport function in the migrating larva of P. macrostoma is subject to indirect regulation by environmental Na+.
The induction of species-specific immunity against Schistosoma japonicum by exposure of rats to ultra-violet attenuated cercariae
Authors: Moloney N. A. , Webbe G. , Hinchcliffe P. 
Published: June 2009

SUMMARYSingle percutaneous immunizations of Fischer rats with 1000 ultra-violet attenuated Schistosoma japonicum cercariae induced 52–88% resistance to challenge 4 weeks later. Increasing this to 3 immunizations induced 90% resistance to challenge, and this level of protection remained undiminished for up to 40 weeks after vaccination. Rats vaccinated with gamma-irradiated S. mansoni cercariae were resistant to challenge with S. mansoni but not S. japonicum. Similarly rats vaccinated with u.v.-attenuated S. japonicum cercariae were not resistant to heterologous challenge. Thus irradiated vaccines are species-specific in both permissive and non-permissive hosts.
Biochemical and ultrastructural investigation of the effect of Stelazine (trifluoperazine) onHymenolepis diminuta(Cestoda)
Authors: Hipkiss Jayne B. , Skinner A. , Branford White C. J. 
Published: June 2009

SUMMARYThe effects of the phenothiazine, Stelazine, onHymenolepis diminutawere investigated. The cestode was incubated for 10 min at 37 °C with 1 mM trifluoperazine, in the presence and absence of Ca2+. Assay of brush border enzymes showed that drug treatment lowered the activities of alkaline phosphatase, Ca2+-ATP'ase, 5′-nucleotidase and type 1 phosphodiesterase. This occurred in parallel with a significant reduction in tegumental protein. Under these conditions gross changes in ultrastructural appearance and cellular organization were observed. There was a lack of ordered microtriches and the distal cytoplasm was absent. Glycogen granules were scattered throughout the cytoplasm within the subtegumental layer. The connective tissue also appeared to be in some disarray. The effects of Stelazine appeared to be dependent on time and were significantly increased when Ca2+was included in the incubation medium. Incubation with the less hydrophobic phenothiazine trifluoperazine sulphoxide had minimal effect on the integrity of the cestode. The results reported here support the premise that certain phenothiazines may be considered as potential cestocidal agents.
Occurrence and biochemical characteristics of cestode lymphocyte mitogens
Authors: Judson D. G. , Dixon J. B. , Skerritt G. C. 
Published: June 2009

SUMMARYThe cestodes Echinococcus granulosus, Taenia multiceps, T. pisiformis, T. hydatigena, Hymenolepis diminuta, Moniezia expansa and Anoplocephala perfoliata all produced substances that stimulated thymidine incorporation by whole blood lymphocyte cultures. This mitogenic activity was demonstrated in metacestode cyst fluids, live protoscoleces and scoleces, parasite culture supernatants, and extracts of adult parasites. T. multiceps metacestode cyst fluid mitogen adhered to, but would not pass through, cellulose dialysis tubing. This adherence was reduced or prevented by D-glucose and by proteins. The mitogen was weakly anionic. With Sephadex G75 gel filtration, its elution volume was greatly decreased when the elution buffer contained 0·5 M D-glucose. Mitogenic activity was protease resistant and could be separated by gel filtration from all the cyst fluid proteins.