bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of the in vitro feeding of Rhipicephalus appendiculatus nymphae for the transmission of Theileria parva
Authors: Waladde S. M. , Young A. S. , Mwaura S. N. , Njihia G. N. , Mwakima F. N.
Published: June 2009

An apparatus for artificial feeding of Rhipicephalus appendiculatus nymphae was modified to improve feeding performance. Heparinized blood was supplied above a treated artificial membrane while the ticks attached below on its undersurface. The feeding apparatus was incubated at 37 °C in an atmosphere of 3% CO2 concentration and a relative humidity of 75–80%. Under these conditions, 91% of the engorged nymphae attained a mean weight of 6–11 mg, and an average of 93% of those nymphae moulted into adults. When this system was used to feed nymphal ticks on blood infected with Theileria parva piroplasms, the mean prevalence of infection in the resultant female and male ticks was 86% and 54%, respectively. The feeding performance and T. parva infection levels were comparable to those of nymphal ticks fed on the blood donor cattle. The apparatus used in this study has potential for modification to suit the artificial feeding needs of other species of ixodid ticks and for use in investigations to examine other tick/pathogen relationships.
Observations on worm population dynamics in calves naturally infected withSchistosoma mattheei
Authors: De Bont J. , Vercruysse J. , Sabbe F. , Ysebaert M. T.
Published: June 2009

The evolution of faecal egg output, worm burdens and tissue egg counts in young calves was monitored during the first year of natural exposure toSchistosoma mattheeiinfection on a Zambian farm. According to the duration of their stay on the farm, these calves were classified into 2 groups of 14 temporary tracers (TT calves) which were introduced on a 2-monthly basis for residential periods of 2 months, and 12 permanent tracers (PT calves) introduced either at the beginning of the experiment (Group A) or 2 months later (Group B) and gradually removed after residential periods of 2, 4, 6, 8, 10 and 12 months on the farm. Worm counts in the TT calves showed that infection occurred throughout the year on the farm and that levels of infection acquired during each period of 8 weeks correlated well with the respective infected snail densities observed at the main transmission site. Marked differences in worm population dynamics were recorded between the 2 groups of PT calves. In Group B animals which apparently were initially exposed to heavy transmission, according to the results from TT calves, much higher worm counts and greater susceptibility to reinfection were observed than in Group A animals initially exposed to lighter exposure. These results suggest that the development of resistance to natural infection withS. mattheeimay depend on the initial exposure to the parasite. Low initial exposures may lead to resistance whereas high initial exposures may result in decreased immune responses resulting in susceptibility to infection.
Reversal of hypoglycaemia in murine malaria by drugs that inhibit insulin secretion
Authors: Elased K. M. , Playfair J. H. L.
Published: June 2009

We have investigated the metabolic disturbances in 2 murine models of blood-stage malaria,Plasmodium chabaudiandPlasmodium yoelii. Blood glucose, plasma insulin and parasitaemia were measured in normal and infected mice before and after treatment with diazoxide, adrenaline, Sandostatin and quinine. Severe hypoglycaemia and marked hypersinsulinaemia developed during both infections. A single injection of diazoxide (25 mg/kg i.p.) or adrenaline (0·03 mg s.c.) lowered insulin concentrations in normal mice, reversed the hypoglycaemia in both infections and significantly reduced the hyperinsulinaemia inP. chabaudi-infected mice (P< 0·0001). Higher doses of Sandostatin (500 μg/kg s.c.) were required to reverse hypoglycaemia. Quinine (25 mg/kg i.p.) significantly increased blood glucose in normal and infected mice (P< 0·001) and no hypoglycaemia was observed in mice with normal blood glucose for more than 3 h. This study shows that the major cause of hypoglycaemia in murine malaria is hyperinsulinaemia rather than high consumption of glucose by host and parasites or chemotherapy with quinine, and that hypoglycaemia can be reversed by correcting the hyperinsulinaemia.
The capacity of the fungusDuddingtonia flagransto prevent strongyle infections in foals on pasture
Authors: Larsen M. , Nansen P. , Grøndahl C. , Thamsborg S. M. , Grønvold J. , Wolstrup J. , Henriksen S. A. , Monrad J.
Published: June 2009

A field trial was conducted to evaluate the potential of the nematode-destroying fungusDuddingtonia flagransto control free-living stages of horse strongyles. In late Spring 2 groups of horses (yearlings) with mixed infections of strongyles were allowed to contaminate 2 equal-sized pastures. One of the groups (F) received a daily dose ofD. flagransmixed in a feed supplement, while the other (C) received a similar amount of supplement without fungus. During a 3-month contamination period strongyle egg counts in faeces and number of infective strongyle larvae harvested from faecal cultures were determined. Grass samples were collected fortnightly. After the contamination period the yearlings were removed and 2 groups of young tracer foals (TF and TC) grazed the fungus and control pastures respectively for 4 weeks, housed for another 15 weeks and then killed to determine their worm burdens. The number of larvae in cultures from group TF was significantly lower than that in TC and herbage infectivity was reduced to a very low level on the pasture grazed by horses fed fungi. The number ofStrongylus vulgarisandStrongylus edentatuslarvae was also significantly lowered in group TF. Cyathostome larvae recovered from the mucosa of the ventral and dorsal colon and from the caecum were significantly lowered in group TF foals. Also, the number of strongyles found in the gut contents of group TF foals were significantly reduced in the dorsal colon, but numbers of worms in the ventral colon and in the caecum were similar to those of the controls.
The ultrastructure of the anterior end of maleOnchocerca volvulus: papillae, amphids, nerve ring and first indication of an excretory system in the adult filarial worm
Authors: Strote G. , Bonow I. , Attah S.
Published: June 2009

A detailed morphological investigation of the anterior sensory organs, the nerve ring and a glomerulus-like structure in maleOnchocerca volvuluswas performed by means of electron microscopy. The 8 head papillae are arranged in the common 4 + 4 pattern of most filarial worms in circles around the mouth opening. The amphidial openings are found between the circles of inner and outer papillae on both sides of the mouth. Inside, several additional nerve axons are seen in the tissue of the anterior tip not related to one of the identified papillar structures. The inner and outer papillae exhibit a remarkably different fine structure, and are part of a complex system of at least 2 different receptor cell types at the anterior tip of the worm. The amphidial channel contains 8 modified cilia; accessory axons are associated with the cytoplasm of the sheath cell. The anterior nerve ring of male worms is located about 150 µm posterior from the outermost tip of the head region. It consists of several fibres coiled around the oesophagus. The comparison of the fine structure of the central nervous system did not show the expected morphological differences associated with the heterogeneous age distribution in the natural worm population. This was in contrast to previous findings with respect to tissues in different parts of the worm. The study also provides the first evidence that suggests the existence of an excretory organ in a filarial worm in the region of the anterior nerve ring. Paired glomerulus-like structures in the lateral chords and a canal formed by a projection of the basal zone of the cuticle were identified.
The effect of infection with Lyme disease spirochetes (Borrelia burgdorferi) on the phototaxis, activity, and questing height of the tick vector Ixodes scapularis
Authors: Lefcort H. , Durden L. A.
Published: June 2009

Little is known about the effects of infection with Borrelia burgdorferi, the bacterium that causes Lyme disease, on its tick vectors. The purpose of this study was to determine the behavioural and ecological effects of infection by the bacterium in nymphal and adult black-legged (Ixodes scapularis) ticks. We found that the effects of infection were more pronounced in adults than in nymphs. Compared to uninfected adults, infected adults were less able to overcome physical obstacles, avoided vertical surfaces, were less active and quested at lower heights. Infected nymphs showed increased phototaxis and attraction to vertical surfaces. Infected nymphs also showed trends toward increased questing height and a greater tendency to overcome physical obstacles although these trends were not statistically significant. These altered behaviours in an infected tick may affect survival or pathogen transmission and may reflect kin selection in the bacterial pathogen.
Infestation with larvae of the sea anemone Edwardsia lineata affects nutrition and growth of the ctenophore Mnemiopsis leidyi
Authors: Bumann D. , Puls G.
Published: June 2009

The lobate ctenophore Mnemiopsis leidyi is a periodically abundant and voracious plankton predator in coastal waters along the east coast of the United States. In the 1980s it was accidentally introduced to the Black Sea where it caused a dramatic reduction in fisheries. We investigated how M. leidyi is affected by infestation with parasitic larvae of the sea anemone Edwardsia lineata. Infested M. leidyi contained 1–30 (median 7) E. lineata larvae. Within M. leidyi most larvae had their mouth in the gastrovascular system near the aboral end of the pharynx. Parasitic E. lineata ingested all food previously ingested and pre-digested by M. leidyi. Non-infested M. leidyi had higher growth rates than infested individuals, which had zero or negative growth rates. Egg production was similar for infested and non-infested M. leidyi of similar size. Simulation based on the empirical data suggests that growing, non-infested, M. leidyi are expected to have a larger life-time egg production than infested shrinking individuals. E. lineata could be at least partially responsible for the sharp decline of M. leidyi populations in fall in US coastal waters. Advantages and disadvantages of E. lineata as a potential candidate for the control of the artificially introduced M. leidyi population in the Black Sea are discussed.
Nippostrongylus brasiliensisinfection evokes neuronal abnormalities and alterations in neurally regulated electrolyte transport in rat jejunum
Authors: Masson S. D. , McKay D. M. , Stead R. H. , Agro A. , Stanisz A. , Perdue M. H.
Published: June 2009

Neuronal abnormalities have been described in the intestine of helminth-infected rats. However, the physiological ramifications of these changes have not been determined. Here, we examined epithelial ion secretion, indicated by increases in short-circuit current (Isc), evoked by electrical transmural stimulation (TS) of enteric nerves in Ussing-chambered jejunal tissues fromNippostrongylus brasiliensis-infected rats. Rats were examined at 10 and 35 days post-infection (p.i.); non-infected rats served as controls. TS resulted in significantly reduced ion secretion in jejunum from 10 day p.i. rats compared to controls or jejunum from 35 day p.i. rats. The TS response in tissue from infected rats had, unlike controls, no cholinergic component. Tissues from both non-infected and infected rats were equally responsive to the muscarinic agonist bethanechol, suggesting that the cholinergic defect was neuronal and not an inability of the epithelium to respond to cholinergic stimulation. However, increases in Isc evoked by exogenous substance P (SP) in tissue from rats 10 day p.i. were reduced in magnitude to approximately 25% of control values. Concomitant with these physiological changes, tissue from infected rats contained increased amounts of substance P immunoreactivity and intestinal sections displayed increased numbers of substance P-immunoreactive nerve fibre profiles at both 10 and 35 days p.i. Thus, followingN. brasiliensisinfection there is a shift in the enteric nervous system away from cholinergic to non-cholinergic regulation, associated with increased amounts of the pro-inflammatory neuropeptide, substance P. We speculate that changes in neuronal structure and function are intimately involved in the co-ordinated multicellular response to intestinal parasitic infection and subsequent gut recovery.
Setaria digitatamicrofilaraemia inMastomys coucha: an animal model for chemotherapeutic and immunobiological studies
Authors: Mukhopadhyay S. , Dash A. P. , Ravindran B.
Published: June 2009

Intraperitoneal implantation of adult gravid females of the bovine filarial parasite,Setaria digitatainMastomys couchawas found to induce microfilaraemia lasting for about 125 days. The microfilariae (mf) could be detected as early as 4 days postimplantation (p.i.) and peak levels of about 30 mf in 20 µl of blood were observed by 21 days. A significant positive correlation was found between mf density and the body weight of recipients pre-implantation. The implanted adult worms were generally viable only for less than 1 week. Implantation resulted in a significant decrease in total leucocytes and erythrocytes, induction of eosinophilia, splenomegaly and anti-erythrocyte autoantibodies. The microfilariae in circulation developed into 3rd-stage infective larvae (L3) when fed ontoAedes aegypti(refm, Liverpool strain). The mf in circulation were found to be eliminated by oral administration of diethylcarbamazine citrate, indicating the usefulness of this model for screening potential anti-microfilarial drugs. During the microfilaraemic phase, priming with tetanus toxoid (TT) resulted in significantly decreased production of anti-toxin levels indicating a state of generalized immunosuppression. Induction of antibodies to various fractionated antigenic components of adult parasites could be demonstrated by enzyme immunoassay (EIA) inM. couchaimplanted with live or cold-stunned adult worms. TheS. digitata–M. couchamodel thus is found amenable to perform chemotherapeutic and immunobiological investigations in experimental filariasis.
Codon usage inCryptosporidium parvumdiffers from that in other Eimeriorina
Authors: Char S. , Kelly P. , Naeem A. , Farthing M. J. G.
Published: June 2009

Codon usage ofCrytosporidium parvumwas compared with those of other EimeriorinaToxoplasma gondiiandEimeria tenellaand revealed a biased use of synonymous codons with a preference for NNU (40·0%) and NNA (33·4%). There was no close resemblance of the codon usage ofC. parvumtoT. gondii(correlation coefficient, r = 0·14) orE. tenella(r = 0·14) but it was similar toEntamoeba histolytica(r = 0·75) andPlasmodium falciparum(r = 0·5). Analysis of the codon usage in homologous gene sequences (actin, β-tubulin) also failed to reveal a close relationship betweenC. parvumandT. gondiiorE. tenella. The low usage codons inC. parvumwere most frequently used codons inT. gondiiandE. tenella. These observations are consistent with 18S rRNA sequence analysis which shows no close relationship ofCryptosporidiumwith other Eimeriorina (Sarcocystis, ToxoplasmaandEimeria) and questions the validity of the current classification ofC. parvum.
Extravascular foci ofTrypanosoma vivaxin goats: the central nervous system and aqueous humor of the eye as potential sources of relapse infections after chemotherapy
Authors: Whitelaw D. D. , Gardiner P. R. , Murray M.
Published: June 2009

Relapse of parasitaemia after drug treatment of trypanosome infections is normally attributed to drug-resistance on the part of the parasite, under-dosage of the drug or reinfection of the host. In addition, inaccessibility of parasites to drug through sequestration in privileged extravascular sites has been shown in the past to occur withTrypanosoma brucei, and we have obtained evidence that extravascular foci ofT. vivaxcan also serve as a source of relapsing infections. Infection of goats with a West African stock ofT. vivaxresulted in severe illness, which was fatal if untreated. During the terminal stage of an acute infection, clinical signs of central nervous system involvement were apparent. Histologically, the choroid plexus was swollen and oedematous, and in some cases meningitis or meningoencephalitis was seen. Trypanosomes could be detected in the cerebrospinal fluid, and also extravascularly in the choroid plexus and meninges. In three cases they were present in the aqueous humor, associated with corneal cloudiness or opacity. Treatment of 2 goats with the trypanocidal drug diminazene aceturate eliminated parasitaemia, but infections in both relapsed about 6 weeks later, despite trypanosomes being undetectable in the bloodstream during the intervening period. We conclude that the relapse infections were caused by re-emergence of trypanosomes from the CNS and/or the eye, where sequestered parasites may have been inaccessible to the trypanocide.
Hymenolepis nana: the fine structure of the ‘penetration gland’ and nerve cells within the oncosphere
Authors: Fairweather I. , Threadgold L. T.
Published: June 2009

The fine structure of the oncosphere of Hymenolepis nana has been investigated by transmission and scanning electron microscopy, together with light microscope observations of JB–4 embedded material. The outer surface of the oncosphere is covered by an epithelial layer, termed the embryonic epithelium. Cell types present within the oncosphere include the penetration gland cell, oncoblast, or hook-forming cells, nerve cells, muscle cells (both somatic and hook), and undifferentiated ‘stem’ cells. The penetration gland is a large, U-shaped structure, situated in the anterior region of the oncosphere, and filled with secretory granules of 2 distinct morphological types. Histochemically, the secretory material yields reactions characteristic of an acid mucopolysaccharide. A proteinaceous-substance and small amounts of glycogen are also present. Up to 4 pairs of ducts from the penetration gland have been observed. They pass through the basal lamina and the epithelial layer to open against the polar filament layer at the anterior end of the oncosphere. Nerve cells are described in a cestode oncosphere for the first time. The cells are paraldehyde-fuchsin-positive and show a high level of secretory activity, as evidenced by the large numbers of dense-cored vesicles produced by the Golgi apparatus in the perikarya; consequently, they are tentatively regarded as possible neurosecretory cells. The vesicles are transported down the axon to be stored in specialized swollen axon terminals, which form definite junctions with the muscle cells.
Pheromone of Ornithodoros spp. (Argasidae) in the coxal fluid of female ticks
Authors: Schlein Y. , Gunders A. E.
Published: June 2009

Coxal secretion of adult female Ornithodoros erraticus was found to contain a sex pheromone that induces in males of this species a mating response towards nymphs smeared with this secretion. Heterospecific coxal fluid from O. tholozani and O. moubata also elicited a mating response from O. erraticus males. Adult O. erraticus females did not evoke courting behaviour when immobilized or killed, but normal mating behaviour was regained when the immobilized females were freed – proving that both pheromone and recognition of a behavioural pattern are essential components of mating behaviour. Secretion of the sex pheromone appears by the 4th day after a blood meal and accumulates with time, thus increasing the number of attempted matings.
Parasites and the fossil record
Authors: Morris S. Conway
Published: June 2009

Parasitologists are fond of alluding to the possible antiquity of their chosen group. They may even place the origin in a specific period of geological time and trace its co-evolution, or lack thereof, with the hosts. These speculations usually make only passing comments on the actual fossil record, but a critical examination suggests that this area can throw much light on both the origins and evolution of parasitism. This review is concerned primarily with the fossil record and its immediate implications. It does not appraise parasite evolution in the light of evidence from sources, often of excellent quality, such as comparative anatomy and physiology or ecology. As some parasitologists may not be entirely familiar with the geological column and time scale, Table 1 depicts these and indicates some records of parasitism mentioned here, together with the major events in this history of life.
Reinfection with hookworm after chemotherapy in Papua New Guinea
Authors: Quinnell R. J. , Slater A. F. G. , Tighe P. , Walsh E. A. , Keymer A. E. , Pritchard D. I.
Published: June 2009

Reinfection with hookworm (Necator americanus) following chemotherapy was studied over 2 years in a rural village in Madang Province, Papua New Guinea. The prevalence of hookworm infection had returned to pre-treatment levels after 2 years, and the geometric mean hookworm burden had returned to 58 % of the pre-treatment value. The rate of acquisition of adult worms was independent of host age, and was estimated as a geometric mean of 2·9–3·3 worms/host/year (arithmetic mean 7·9–8·9 worms/host/year). There was significant predisposition to hookworm infection; the strength of this predisposition did not vary significantly between age or sex classes.
Epidemiology of Toxocara canis in red foxes (Vulpes vulpes) from urban areas of Bristol
Authors: Richards D. T. , Harris S. , Lewis J. W.
Published: June 2009

A descriptive epidemiological survey was undertaken of the ascarid nematode Toxocara canis in 521 red foxes (vulpes, vulpes) during the period January 1986 to July 1990. Age–prevalence and age–intensity profiles show that worm are significantly higher in cubs than in subadult or adult foxes and higher in subadult than in adult foxes. variations in worm burdens occur, with the highest prevalences and intensities being found during the spring, when are born, and in the summer months. Prevalences and intensities then decrease during the autumn and winter months both subadult and adult foxes, but, during this period, prevalences are significantly higher in male than in female Variations in worm burdens in the fox population are likely to be related to the reproductive cycle of the fox, with proportion of cubs becoming infected in utero. The role of the fox in the transmission of T. canis in the urban environment is discussed.
Viability of Onchocerca volvulus in vitro
Authors: Strotel G. , Bokhof A. , Comley J. C. W.
Published: June 2009

The use of a selective schedule of tests to identify a viable population of isolated adult Onchocerca volvulus (Nematoda: Filarioidea) has been investigated in a large worm population. The study was initiated to develop methodology appropriate to test new candidate macrofilaricides for their in vitro activity against O. volvulus. After removal from the host the viability of isolated intact parasites was estimated by assessing the motility indices of male worms, and the colorimetric quantification of the reduction of the bioreducible tetrazolium reagent XTT and lactate output by female worms. Additionally the motility of whole females and the movement of inner organs of female worms were scored quantitatively. These response parameters were used to sort the adult worms into viability groups at the start of the in vitro culture. The adult worms were then observed for 6 days and viability was assessed regularly during the culture period. At the end of the culture period, the reduction of the water-insoluble tetrazolium reagent MTT was used to determine the formazan formed by the entire male and female worms. The response parameters used at the start of the culture proved to be highly predictive for detecting viable and non-viable adult worms. In the group of worms selected as ‘viable’ around 70% kept their motility and metabolic activity at a high level until the end of the culture compared to the initial level. In contrast, none of the female worms and only 13% of the male worms categorized as ‘poorly viable’ demonstrated a motility index or metabolic level at the end of the culture period that was comparable to that of the worms in the ‘viable’ groups. For female worms the lactate output correlated significantly with weight whereas no correlation was seen between MTT reduction and weight.
Social behaviour, stress and susceptibility to infection in house mice (Mus musculus): effects of duration of grouping and aggressive behaviour prior to infection on susceptibility toBabesia microti
Authors: Barnard C. J. , Behnke J. M. , Sewell J.
Published: June 2009

Unrelated and initially unfamiliar male CFLP mice, maintained for different periods in groups of 6, differed in both their rate of clearance ofBabesia microtiand the time taken to reach peak parasitaemia in relation to their aggressive behaviour within groups prior to infection. Males maintained in groups for shorter periods and showing more aggression within their group were slower to clear infection and males showing more marked external evidence of aggressive interaction reached a peak of parasitaemia sooner. Serum IgG and corticosterone analyses were consistent with increased aggression causing stress-induced immunodepression but relationships with aggression and social status were not simple. Males showing more aggression tended to enter their groups with higher levels of corticosterone and, to a lesser extent, reduced levels of IgG compared with other mice. The results thus suggest that increased susceptibility to disease may be a cost to males aggressively maintaining high social status.
The effect of temperature upon the establishment and survival of the cestodeCaryophyllaeus laticepsin orfe,Leuciscus idus
Authors: Kennedy C. R.
Published: June 2009

Farm-reared Leuciscus iduswere experimentally infected with the intestinal tapewormCaryophyllaeus laticeps, and maintained at different temperatures. At 12 °C and lower temperatures there was an initial loss of parasites after infection, but the survivors persisted for up to 1 month. At 18 °C only temporary survival of the parasite was possible, and worms were killed and rejected after 3 days. Experimental transplants to fresh hosts after 2 days indicated that the factors responsible for the death of the parasites became effective within this period.Neither inhibition of peristalsis nor host starvation affected the parasite's survival. The speed of the response to the parasite indicates that circulating antibodies produced in response toC. laticepsand directed specifically against it cannot be involved in the rejection. Other possible mechanisms of rejection are discussed, together with the significance of the results to the interpretation of data based on field observations.

I should like to thank Mr J. Harris for allowing me to refer to some of his unpublished data and for helpful discussions.
Isolation and characterization of a putative collagen gene from the potato cyst nematodeGlobodera pallida
Authors: Jones J. T. , Curtis R. H. , Wightman P. J. , Burrows P. R.
Published: June 2009

A cDNA clone encoding a full length putative collagen has been isolated in a screen of a mixed stageGlobodera pallidaexpression library. Comparison of the deduced amino acid sequence of this molecule with other collagens suggests it is a cuticular collagen and a member of thecol-8subfamily of collagen genes. Northern blots show the gene is expressed specifically in gravid, adult females of the parasite as compared to second (invasive) stage juveniles and virgin females. Preliminary immunocytochemical studies indicate this collagen is present in areas other than the cuticle; these findings and the potential functional role of this collagen are discussed.
Characterization ofEncephalitozoon hellem(Microspora) isolated from the nasal mucosa of a patient with AIDS
Authors: Hollister W. S. , Canning E. U. , Colbourn N. I. , Curry A. , Lacey C. J. N.
Published: June 2009

A microsporidium of the genusEncephalitozoonwas isolated into culture from the nasal epithelium of a patient with AIDS. It was compared within vitroisolates ofEncephalitozoon cuniculiand the type isolate ofEncephalitozoon hellemby SDS–PAGE and by Western blotting with murine antisera raised toE. cuniculi, E. hellemand the nasal isolate, monoclonal antibodies raised toE. cuniculiand sequential sera from the patient. All tests showed similarities betweenE. hellemand the nasal isolate but differences between these two isolates andE. cuniculi. Minor protein differences betweenE. hellemand the nasal isolate were not considered sufficient to separate them at the specific level. The new isolate is named the Wainwright isolate ofE. hellem. The ultrastructure of the Wainwright isolatein vitrowas similar to that of the parasitein vivobut there was a greater tendency for disruption of the parasitophorous vacuoles. The deposition of the electrondense surface coat on the sporogonic stages ofE. hellem, as a uniform layer which later thickens, is in contrast to its deposition as broad bands, which later join up, inE. cuniculi. This may be a useful character in distinguishing the species without recourse to analysis of protein profiles.
Analysis of mixed parasite populations ofTheileria sergentiusing cDNA probes encoding a major piroplasm surface protein
Authors: Matsuba T. , Kubota H. , Tanaka M. , Hattori M. , Murata M. , Sugimoto C. , Onuma M.
Published: June 2009

The gene for the 32 kDa surface protein (p32) ofTheileria sergentiwas cloned into λgt11 and its nucleotide sequence was determined. The gene encodes a protein of 283 amino acids as deduced from its nucleotide sequence with a 22 residue N-terminal signal peptide. Using this cDNA as a probe we have isolated another two clones from a cDNA library with a CDM8 vector system derived from the same parasite stock. Comparison with three cDNA clones revealed differential polyadenylation and differences in sequences of non-coding regions. Within the coding regions, there were nucleotide transitions which affected thePstI-restriction site, and one of the transitions was also accompanied by an amino acid substitution (Ala to Gly). Southern blot analysis showed hybridization pattern changes among the parasites isolated from individual calves at different times after infection. From these results, we conclude that at least 3 genetically different parasite populations may coexist, and that transition to predominant parasite populations might occur during persistent infections in a host, possibly to evade the host immune responses.
Ligula intestinalis(L.) (Cestoda: Pseudophyllidea): polarization of cyprinid leucocytes as an indicator of host-and parasite-derived chemoattractants
Authors: Taylor M. J. , Hoole D.
Published: June 2009

Freshly isolated pronephric leucocytes from roach,Rutilus rutilusand gudgeon,Gobio gobiowere exposed to extracts of plerocercoids ofLigula intestinalisfrom these two cyprinid fish. Addition of the extracts or an increase in incubation temperature from 10 to 20 °C induced polarization of neutrophils and L1 granulocytes. Cells were transformed from their typical spherical shape to elongate forms possessing a ruffled leading edge. Extracts obtained from gudgeon-Ligulastimulated polarization of both roach and gudgeon leucocytes at 10 and 20 °C. In contrast, extracts from roach-Ligula, whilst having little effect at 10 °C, suppressed temperature-induced polarization of leucocytes at 20 °C. Addition of serum to all the essays enhanced polarization and abolished the roach-Ligula-induced suppression. It is suggested that leucocyte chemoattractants are present inLigulafrom roach and gudgeon and only parasites from the former host contain an inhibitor of polarization. In addition, host-derived factors possibly complement, may be involved in leucocyte chemoattraction.
The viability of Sphaeridiotrema pseudoglobulus (Digenea) eggs following cold water storage as a possible overwintering strategy
Authors: McKindsey C. W. , McLaughlin J. D.
Published: June 2009

Sphaeridiotrema pseudoglobulus is a digenean parasite believed to be involved in a yearly fall die-off of ducks in Québec, Canada. Hatching characteristics of eggs stored at 7°C for 0–28 weeks in the lab and following maintenance overwinter in a lake are described. The hatching success of eggs stored for 4–28 weeks remained constant (71–81 %) but slightly less than that observed in fresh eggs (90%). The hatching success of eggs kept overwinter under natural conditions did not differ from that of eggs stored an equivalent length of time in the lab at 7°C (74·7 and 75·8%, respectively). With the exception of fresh eggs (17·7 days), the mean hatch time of eggs steadily decreased with increased storage time (18·9 days following 4 weeks storage to 11·4 days at 28 weeks storage) due to a slow embryonation of the eggs at 7°C. Hatching characteristics of a subsample of eggs incubated at 10, 15 and 20°C were compared and the embryonation rate was found to increase with incubation temperature. The majority of eggs stored at 10°C embryonated but failed to hatch. When their incubation temperature was raised to 15°C, a further 46% hatched within the following week. The survivorship functions of miracidia hatching from eggs stored for 8, 12, 16 and 20 weeks differed but the mean expected life-span of the miracidia did not decline with increasing storage time as expected. The results of these experiments are discussed in relation to the potential importance of overwintered eggs in the development of the infective pool of metacercariae.
The attachment of the monogenean Entobdella soleae to the skin of the common sole
Authors: Kearn G. C.
Published: June 2009

The muscular saucer-shaped haptor of the monogenean parasite Entobdella soleae is attached to the skin of its host Solea solea by means of a suction pressure generated within the sea-water-filled cavity enclosed between the cup-shaped haptor and the skin of the fish. The suction pressure is produced by the action of a pair of extrinsic muscles which are situated in the body of the parasite. Each extrinsic muscle communicates with the haptor by means of a long tendon which passes through a fair-lead in a prop-like accessory sclerite and is inserted on the end of a girder-like anterior hamulus embedded in the roof of the concavity of the haptor. The pull exerted by the muscles lifts the girders and the roof of the suction cup in which they are embedded relative to the props, thereby producing a suction pressure.

An electron microscope was used to investigate the ultrastructure of the tendon, which was found to consist largely of unbranched banded fibrils which differed from the collagen fibrils of vertebrate tendon in their diameter and periodicity.

I would like to express my thanks to Dr J. Llewellyn for suggesting the problem and for much helpful discussion. I am also grateful to Dr M. P. Osborne for tuition on the cutting of sections for electron microscopy. The work was conducted during the tenure of a Fishery Research Training Grant from the Development Commission.
Spermatophores in the Monogenean Entobdella diadema Monticelli from the skin of sting-rays, with a note on the taxonomy of the parasite
Authors: Llewellyn J. , Euzet L.
Published: June 2009

Entobdella diadema produces spermatophores from a pair of follicular glands lying one on each side of the body alongside the main nerve cord, and the secretion of these glands is stored in a two-chambered reservoir within the cirrus-sac.

The vagina is made up of two regions, a wide distal part to receive, accommodate and digest the spermatophores, and a proximal narrow part connected through the vitelline reservoir with the oviduct.

E. diadema Monticelli, 1901, is shown to be distinct from E. bumpusii Linton, 1900, and has been recorded from two new hosts, Dasyatis pastinaca at Plymouth, and Myliobatis aquila at Naples.

We wish to thank the directors and staffs at the Plymouth Marine Laboratory and at the Stazione Zoologica, Naples, for providing excellent facilities for the above studies to be carried out. The work was assisted by a grant to one of us (J. L.) from the Trustees of the Browne Fund, to whom grateful acknowledgement is made.
Characterization of aLeishmaniaantigen associated with cytoplasmic vesicles resembling endosomal-like structure
Authors: Yahiaoui B. , Loyens M. , Taibi A. , Schöneck R. , Dubremetz J. F. , Ouaissi M. A.
Published: June 2009

In the present study we have used antibodies toLeishmania majorpromastigote antigens which were eluted from a glutathione-agarose column (LmGbp) and could identify several parasite components among differentLeishmaniaspecies by using immunoprecipitation and Western blot techniques. The results also showed that some of LmGbp are present among the molecules released into the culture medium. Moreover, immunofluorescence assays clearly demonstrated that LmGbp are expressed by intracellular amastigotes. The electron micrographs of thawed cryosections ofL. major-infected cells revealed that the antigens were associated with the membrane of the phagocytic vacuole. Moreover, the Western blot technique allowed us to identify, using otherLeishmaniaspecies extracts and anti-LmGbp antibodies, a major polypeptide of an apparent molecular mass of 66 kDa. Immunofluorescence studies suggested that the 66 kDa polypeptide is associated with intracytoplasmic vesicles. Cryosections ofLeishmaniapromastigotes improved the fine structure preservation of the organelles and enabled a number of features to be seen, particularly the structures considered as vesicles, which appeared as a complex tubulo-vesicular structure resembling mammalian cell endosomes andLeishmaniaorganelles previously named ‘megasomes’. Further studies using antibodies against the native 66 kDa protein will be needed to investigate the localization of the protein at the ultrastructural level and to follow its intracellular vesicular traffic.
Host-related DNA sequences are localized in the body of schistosome adults
Authors: Irie Y. , Iwamura Y.
Published: June 2009

The localization of host (mouse)-related DNA sequences in the adults and cercariae ofSchistosoma japonicumandS. mansoniwas examined byin situhybridization using32P-labelled probes. The hybridization signals to the sequences of the mouse type C and type A retroviruses were clearly observed in the subtegumental layer and inner tissues ofS. japonicumadults. In contrast, it was hard to find any signals to these sequences inS. mansoniadults. Distinct signals to theenv-specific region of the mouse ecotropic type C retrovirus were observed in the subtegumental layer and inner tissues ofS. mansoniadults. No signal to the sequence of the mouse type B retrovirus was found on the sections of either schistosome adult. The signals to the sequence of the genomic clone SmM51 derived from maleS. mansoniwere found in the tissues of both the schistosome adults. The signals to the sequences of the mouse type A andenv-specificregion of ecotropic type C retroviruses were not seen in the cercariae of each species, whereas the signals to the sequence of SmM51 were detected inS. mansonicercariae. These observations suggest that host-related DNA sequences might be incorporated unequally into the schistosome genome during development in the final host.
Acetylcholinesterase in infective-stage larvae of Haemonchus contortus, Ostertagia circumcincta and Trichostrongylus colubriformis resistant and susceptible to benzimidazole anthelmintics
Authors: Sutherland I. A. , Lee D. L.
Published: June 2009

The amounts of acetylcholinesterase (AChE) in homogenates of infective-stage larvae of strains, from different countries, of Haemonchus contortus, Ostertagia circumcincta and Trichostrongylus colubriformis resistant or susceptible to benzi-midazole (BZ) anthelmintics, were compared using a rapid colorimetric assay. The levels of AChE were much greater in those strains which were BZ-resistant than in BZ-susceptible populations. The larvae of susceptible and resistant H. contortus contained less AChE than did the larvae of the other two species. One-way analysis of variance showed that the observed differences between susceptible and resistant strains were significant in each of the species studied. It is suggested that the extra enzyme may act as an anthelmintic-detoxifying enzyme, may inactivate the active site of the anthelmintic or may prevent binding of the anthelmintic to its receptor
The amount of acetylcholinesterase on the parasite surface reflects the differential sensitivity of schistosome species to metrifonate
Authors: Camacho M. , Tarrab-Hazdai R. , Espinoza B. , Arnon R. , Agnew A.
Published: June 2009

Acetylcholinesterase (AChE) is present in all stages of the life-cycle of schistosomes and is located in muscle and on the surface of the parasite. Metrifonate is a drug that inhibits AChE. We compared the AChEs from three schistosome species (Schistosoma mansoni, Schistosoma haematobiumandSchistosoma bovis) that have different susceptibilities to metrifonatein vivo. Sensitivities to AChE inhibitors were similar. The subunits of AChE were 110 kDa and 76 kDa and the dominant molecular form of AChE was a G2 form in all three species. This was the major form on the tegument while additional molecular forms were associated with the internal tissues. Differences in relative amounts of AChE activity between these species were found in the adults but not in the schistosomula. At the adult stage the major difference between species lay in the relative amounts of AChE activity in their teguments.S. haematobiumteguments carried 20 times andS. bovis6·9 times the activity present onS. mansoniteguments. These quantitative differences associate with the relative sensitivities of these species to metrifonate.
The relationship between Pseudodiplorchis americanus (Monogenea) density and host resources under controlled environmental conditions
Authors: Tocque K. , Tinsley R. C.
Published: June 2009

A previous study has shown that, under natural conditions, energy reserves of the desert toad, Scaphiopus couchii, are negatively related to the density of infection by Pseudodiplorchis americanus. However, this was based predominantly on collections of active animals from breeding congregations and inevitably selected toads which were in good condition. The parasite, a blood-feeding monogenean, occurs in burdens of up to 30 worms/host (mean intensity 6 worms/host) and represents a significant drain on reserves because the host does not feed during a 10-month hibernation. Field studies cannot resolve the possibility that larger worm densities are not observed in nature due to parasite-induced host mortality. The present study was conducted during investigations of P. americanus development and survival under controlled laboratory conditions, utilizing experimentally infected hosts which created worm densities larger than those observed in natural populations. At all temperature regimes, infected animals had smaller fat bodies than those uninfected but differences were generally not statistically significant due to large individual variations, presumably resulting from variations in past feeding efficiency. At cool temperatures (15–20 °C) there was no density-dependent effect on host fat body weight, and at a diurnal temperature cycle of 20–34 °C (simulating that experienced by host and parasite during the summer months), the effects of high temperatures were greater than the effects of infection, due to increased toad metabolic rates. The most significant effects of P. americanus were observed in hosts that began hibernation in relatively poor condition and experienced moderate temperatures (25 °C) during hibernation. The toads generally maintained packed blood cell levels (PCV) levels even when fat body weights were low, but infected animals had a lower PCV irrespective of fat body levels. In animals unfed after field collection, PCV was reduced in uninfected toads and was even lower in infected animals. Although very heavily infected toads (burdens of 35–95 worms/host) were generally in poorer condition than uninfected toads they still survived long-term hibernation under extreme nutritional stress. This study therefore confirmed observations made in field studies that there is a density-dependent relationship between the hosts' survival prospects and P. americanus infection. However, given the large variability in feeding efficiency and stored resources between individual toads, there is no evidence that the most heavily infected toads would have been unrepresented in field samples due to parasite-induced mortality.
The cuticle of adultNippostrongylus brasiliensis
Authors: Lee D. L.
Published: June 2009

The cuticle of adults ofNippostrongylus brasiliensishas been described using histological, histochemical and ultrastructural techniques.

The cuticle has the following layers: an outer triple-layered membrane; a single cortical layer; a fluid-filled layer which is traversed by numerous collagen fibrils; struts which support the fourteen longitudinal ridges of the cuticle and which are suspended by collagen fibrils in the fluid-filled layer; two fibre layers, each layer apparently containing three layers of fibres; and a basement lamella.

The fluid-filled layer contains haemoglobin and esterase.

The muscles of the body wall are attached to either the basement lamella or to the fibre layers of the cuticle.

The mitochondria of the hypodermis are of normal appearance.

The longitudinal ridges of the cuticle appear to abrade the microvilli of the intestinal cells of the host.

Possible functions of the cuticle are discussed.

I wish to thank Dr P. Tate, in whose department this work was done, for helpful suggestions and criticism at all stages of this work, and Mr A. Page for technical assistance. I also wish to thank Professor Boyd for permission to use the electron microscope in the Department of Anatomy.
Certain aspects of the host-parasite relationship of Nematospiroides dubius (Baylis). I. Resistance of male and female mice to experimental infections
Authors: Dobson Colin
Published: June 2009

1. It has been shown that there is a difference between the resistance of male and female mice to infection withNematospiroides dubius.

2. More parasites were harboured, during both the larval and adult parasitic phases, by male mice.

3. These worms were found to occupy a similar relative length of the intestine between the stomach and the caecum in male and female mice infected for either 5 or 10 days.

4. The relative length of the intestine infected on the fifth day was significantly greater than that infected on the tenth day.

This investigation was carried out during the tenure of a Research Studentship from the Department of Scientific and Industrial Research. I should like to thank Professor I. Chester Jones, in whose department the work was done, for the facilities provided and Dr E. T. B. Francis for his helpful and critical supervision.