bluuebunny/crossref_metadata_2025 huggingface dataset:
Robenidine-dependence in a strain of Eimeria maxima
Authors: Joyner L. P. , Norton C. C.
Published: June 2009

A robenidine-resistant strain of Eimeria maxima was found to be drug-dependent and developed satisfactorily only in birds which were receiving the drug in the diet. Normal parasite development occurred in the presence of 132 ppm of robenidine in the food.
Cytology and Kinetics of microgametogenesis and fertilization in Plasmodium yoelii nigeriensis
Authors: Sinden R. E. , Croll N. A.
Published: June 2009

The sexual development of the microgametocyte of Plasmodium yoelii nigeriensis may be subdivided into microgametogenesis which includes exflagellation, dispersal of the gametes and fertilization. Under our experimental conditions microgametogenesis takes about 8–15 min at 20 °C, the duration of this period being inversely related to temperature. Exflagellation takes less than 1 min, subsequent dispersal of gametes may continue for 40 min. We find that exflagellation is totally inhibited in vitro by temperatures of 30 °C and above, and by certain invertebrate tissue culture media. Exflagellation may occur within a persistent host cell plasmalemma, which seriously impedes the escape of the 8 microgametes.
Microgametes move by sinusoidal or helical waves which may be rapid (10 waves/s), slow (< 1 wave/s) or they may be immobile. Microgamete activity, which is alternately rapid/slow or slow/immobile, declines linearly with time. Fertilization which takes less than 1 min results from characteristic behavioural changes by the microgamete; vibratory waves are responsible for the penetration of the macrogamete by the microgamete. The microgamete completely enters the macrogamete and therein continues its cyclical activity.
Hatching in the monogenean parasiteDictyocotyle coeliacafrom the body cavity ofRaja naevus
Authors: Kearn Graham C.
Published: June 2009

When eggs of the monogeneanDictyocotyle coeliaca, a parasite from the body cavity ofRaja naevus, are incubated in alternating 12 h periods of light and darkness at 12 °C the marginal hooklets appear between 75 and 90 days after collecting the eggs from the host's body cavity and hatching begins after about 102 (96–109) days. Hatching occurs continuously throughout the light and dark periods so that there is no daily hatching rhythm, and host skin mucus and fluid from the host's body cavity (previously deep frozen and thawed before use) are ineffective as hatching stimulants. The significance of these observations in relation to host behaviour is discussed.
Mycoses, bacterial infections and antibacterial activity in sandifies (Psychodidae) and their possible role in the transmission of leishmaniasis
Authors: Schlein Y. , Polacheck I. , Yuval B.
Published: June 2009

High incidence of mycoses were found in the guts and malpighian tubes of Phlebokomus papatasi from the Jordan Valley and P. tobbi from Zakinthos, Greece. Infections with several different bacteria were also found in the guts of female P. tobbi. Fungi cultured from guts of laboratory reared P. papatasi that had similar mycoses were identified as Aspergillus scierotiorum and Saccharomyces cerevisiae. Fungi-infected laboratory reared P. papatasi were refractory to artificial infections with a Leishmania major strain specific to them. The crop contents of P. papatasi, where sugar meals are stored, demonstrated antibacterial activity against the following bacterial species in culture: Escherichia coli, Staphylococcus aureus, Shigella sonnei, Streptococcus group A and Pseudomonas aeruginosa. It is postulated that the bacteria-free gut normal to sandflies is effected by the bacterial inhibitor present in the crop.
Isolation, fractionation and partial characterization of the tegumental surface from protoscoleces of the hydatid organism, Echinococcus granulosus
Authors: McManus D. P. , Barrett N. J.
Published: June 2009

Several approaches were adopted for the disruption and removal of the tegumental surface from protoscoleces of the horse strain of the hydatid organism, Echinococcus granulosus. The effectiveness of each method and the purity of subsequent microthrix-enriched fractions obtained by differential centrifugation were evaluated by electron microscopy, by the amount of protein released and by the degree of enrichment of surface plasma membrane marker enzymes. Incubation in saponin for 10 min produced the purest microtriche preparation, but in low yield; freeze/thawing, incubation in Triton X-100 for 10 mm or in saponin for 20 min produced fractions containing significant amounts of relatively pure microtriches, but mild homogenization was a poor method for surface disruption and subsequent isolation of microtriches. Phosphodiesterase, adenosine triphosphatase (total and ouabain-inhibited), leucine aminopeptidase and glutamyltransferase were active in the protoscoleces but none were enriched in any of the microthrix fractions. In contrast, alkaline phosphatase, acid phosphatase, 5′ nucleotidase and maltase were enriched significantly in all of the isolated microtriche preparations, which suggests that these enzymes are predominantly surface membrane bound. The protein profiles of the microthrix-enriched fractions, following SDS—PAGE, were basically similar, although there were some qualitative and quantitative differences in the proteins released by each isolation procedure. Three major PAS-staining components were present in all the preparations and these probably originated from the glycocalyx. One of these PAS-positive components, with an approximate molecular weight of 110 kDa, may be a glycoprotein specific to the horse strain of E. granulosus.
Propagation ofNosema eurytremae(Microsporida: Nosematidae) from trematode larvae, in abnormal hosts and in tissue culture
Authors: Higby G. C. , Canning Elizabeth U. , Pilley Barbara M. , Bush P. J.
Published: June 2009

Propagation ofNosema eurytremae, a microsporidian pathogen of trematode larvae, was investigated by inoculation of spores into the haemocoele of insects and by growth in tissue cultures. Locusts and the larvae of three lepidopteran species were good hosts but cockroaches were not. Low replication was obtained in one lepidopteran species afterperos infection. Antibiotics controlled bacterial growth in suspensions of microsporidian spores but fungi were unaffected by all antibiotics tested, except at concentrations detrimental to the microsporidia. All stages of the microsporidium developed in cell lines ofXenopus laevisandAedes pseudoscutellariswhen spores were induced to hatch in contact with cell monolayers: theAedesculture was contaminated by yeasts. Repeated washing of theXenopuscells with fresh medium, after the sporoplasms ofN. eurytremaehad penetrated the cells, removed yeast contaminants and sterile cultures were obtained. Replication during 4 passages over 53 days was only 100 to 200-fold compared with the original inoculum but spores harvested from the cultures were infective to a fresh culture and toPieris brassicaeby inoculation into the haemocoele.
Genetic resistance to helminths. The influence of breed and haemoglobin type on the response of sheep to primary infections withHaemonchus contortus
Authors: Altaif K. I. , Dargie J. D.
Published: June 2009

The possible existence of strain and breed differences in the response of sheep to primary infections withHaemonchus contortuswas examined by comparing the establishment and pathogenic effects of the parasite in Scottish Blackface and Finn Dorset sheep grouped according to haemoglobin type and infected with 7–10000 3rd-stage larvae. Homozygous haemoglobin A-type sheep of both breeds had lower worm burdens and faecal egg outputs, and suffered less severe clinical and pathophysiological disturbances than animals homozygous for haemoglobin B. In addition, Scottish Blackface sheep displayed similar advantages over Finn Dorsets with the same haemoglobin type and variations in the severity of the disease as judged by a variety of pathophysiological indices correlated closely with parasite numbers. It was therefore concluded that genetic resistance operated primarily against worm establishment and that, barring the unlikely involvement of non-specific physiological factors, this was controlled by the immune response elicited. The nature of this response is unknown, but appeared to operate only against the larval stages, since the size and metabolic activities of the surviving worms were similar in all animals. In a subsequent experiment, designed to examine the response of Scottish Blackface sheep to heavy infection (45000 larvae), there was no correlation between worm establishment and haemoglobin type. This was possibly due to a delayed immune response arising from exposure to excessive amounts of antigen.
The stimulation of daughter redia production during the larval development of Fasciola hepatica
Authors: Wilson R. A. , Draskau Tove
Published: June 2009

In snails maintained at 20 °C rediae of Fasciola hepatica emerge from sporocysts from 11 days after infection onwards. The number of mother rediae rises steadily thereafter until at least 40 days after infection. Daughter rediae are seldom observed in mother rediae dissected from snails maintained at 20 °C. Their production can, however, be stimulated by subjecting the snail host to starvation, to low, and to high temperature shocks. The parasite is susceptible to stress from immediately after infection for about 16 days, when maintained at 20 °C. In general, the more extreme the shock, the greater is daughter redial production. Increasing the length of the period of stress from 12 h up to 9 days does not increase the production of daughter rediae, nor does repeated on/off cold shocks or continuous maintenance at 10 °C. Daughter rediae develop more rapidly than cercariae and leave the mother rediae several days earlier. There is no evidence that presence of daughter rediae coincides with the suppression of cercarial production. The findings are discussed with reference to possible mechanisms by which parasite development might be controlled.
The lethal effect of mebendazole on secondaryEchinococcus granulosus, cysticerci ofTaenia pisiformisand tetrathyridia ofMesocestoides corti
Authors: Heath D. D. , Christie Marion J. , Chevis R. A. F.
Published: June 2009

Oral administration of mebendazole at a rate of 1 g/kg ieed (approximately 50 mg/kg body weight/day) for 14 days killed mature and immature cysticerci ofTaenia pisiformisin rabbits, and multiplying tetrathyridia ofMesocestoides cortiin mice. Progressive degrees of parasite damage caused by mebendazole treatment could be assessed by histological examination of calcareous corpuscles. A single subcutaneous injection of 10% mebendazole in carrier, at a rate of 100 mg/kg body weight, resulted in the death of allM. cortitetrathyridia in mice within 4 weeks, but the drug in saline was slowly mobilized and was relatively ineffective. Neither subcutaneous injections of mebendazole in saline or in carrier could kill cysticerci ofT. pisiformiswithin 5 weeks, but the drug in carrier was effective after several months. Mebendazole in saline was effective when injected intraperitoneally, but adhesions often resulted from this route of administration.Echinococcus granulosusprotoscoleces administered to mice by intraperitoneal injection were rapidly encapsulated by host lymphoid cells. The vesiculating protoscoleces were all contained within a fibrous capsule for more than 2 months after infection, but by 4 months almost all had grown free of the host reaction. Treatment of the encapsulated protoscoleces with mebendazole in feed for 14–21 days caused collapse of the outer cysts and death of the germinal membrane of all but the innermost protoscoleces. Six weeks later, however, cysts had regrown from surviving germinal tissue and a further treatment with mebendazole in feed for 14–21 days again did not destroy all germinal cells. Treatment of the 4-month-old scoleces with mebendazole in feed for 14 days caused all cysts to collapse and destroyed practically allE. granulosusgerminal tissue. Three subcutaneous injections of mebendazole at fortnightly intervals, of drug in saline at 500 mg/kg body weight, or in carrier at 100 mg/kg body weight, were required in order apparently to kill all secondary cysts ofE. granulosus. Host lymphoid cells were not able to traverse the laminated membrane of either untreated or collapsed cysts, and it has been shown that only a small amount of living germinative tissue is required to produce a newE. granulosus cyst. These factors could contribute to the relative ability ofE. granulosuscysts to recover from mebendazole treatment, compared with cysticerci or tetrathyridia. The effectiveness of mebendazole thus seemed to depend on the formulation of the drug and its route of administration. Mebendazole is probably the first anthelmintic to have a lethal effect on larval cestodes. When applied orally there do not appear to be any adverse effects due to treatment.
Patterns in helminth communities: why are birds and fish different?
Authors: Kennedy C. R. , Bush A. O. , Aho J. M.
Published: June 2009

Recently, some authors (Kennedy, 1981; Price & Clancy, 1983) have argued that there are fundamental differences between the communities of helminths in fish and bird hosts. Such differences are foreshadowed by the work of Dogiel (1964) and are apparent from survey data (e.g. Threlfall, 1967; Bakke, 1972; Hair & Holmes, 1975 on birds, and compare Chubb, 1963; Mishra & Chubb, 1969; Wootten, 1973; Ingham & Dronen, 1980 on fish). Questions still remain, however, as to whether the distinctions are truly justified and whether the differences are really fundamental. In this paper, we address these questions by examining helminth diversity in a series of hosts. We then discuss and provide explanations for the observed differences.
Energy metabolism and its regulation in the adult liver flukeFasciola hepatica
Authors: Lloyd G. M.
Published: June 2009

The adult liver fluke,Fasciola hepatica, inhabits the bile duct of its final host, usually cattle or sheep. The veterinary aspects of infection withF. hepaticacan represent a major problem and consequently fascioliasis can have serious economic effects. As recently as 1972 the loss in revenue due to liver fluke infestations in the UK was estimated at an incredible £50 million per annum (Coles, 1975). Not only canF. hepaticainfect cattle and sheep, but also outbreaks of human disease have been reported. The last serious outbreak in Britain was in 1968 when at least 49 cases were identified (Ashton, Boardman, D'Sa, Everall & Houghton, 1970; Hardman, Jones & Davies, 1970).
Membrane potentials in an acanthocephalan worm (Macracanthorhynchus hirudinaceus)
Authors: Miller D. M. , Wong B. S. , Dunagan T. T.
Published: June 2009

The resting membrane potential of the acanthocephalan rete system in Macracanthorhynchus hirudinaceus was −35±1·5 mV (n = 20) and was dependent upon the external potassium concentration. The membrane potential reached 0 mV when the external potassium concentration was 160 mM. Spontaneous spike potentials of 45 mV ± 10 were dependent on calcium flux. The membrane potential was depolarized by acetylcholine, potassium-free medium, calcium ions and chloride-free medium but not by changes in the external sodium concentration. Spontaneous potentials were increased in number by acetylcholine and calcium at concentrations above 3 mM, but were decreased in number by chloride- and calcium-free medium. Hence the rete system potentials are very similar to smooth muscle potentials in many respects.
Evolutionary implications ofTribolium confusum–Hymenolepis citelliinteractions
Authors: Schom C. , Novak M. , Evans W. S.
Published: June 2009

Hymenolepis citellicaused a marked mortality inTribolium confusumduring the first 14 days of infection. The mortality was higher when the beetles were starved for 6 days immediately prior to infection (73–93%) than when they were starved for 1 day (51%). Regardless of the starvation time, the majority of beetle deaths occurred between days 8 and 11 post-infection (p.i.) and the precise survival time for individuals tended to vary inversely with the number of parasites they contained. With few exceptions beetles that survived until day 15 p.i., when the experiments were terminated, contained 14 or fewer cysticercoids, whereas those that died on or before day 14 p.i. contained 20 or more parasites. Mortality was equally high in both sexes but the mean survival time was significantly shorter for female beetles (8·8 days) than for males (9·6 days). Also, parasite development rate varied with the sex of the host. When parasite populations recovered from beetles that died on the same day were compared, the degree of development attained by those from males was significantly higher than in the populations grown in female hosts. The line ofH. citelliused in these experiments has been maintained in the laboratory for the past 5 years. The results obtained with the current generation of this line were compared with those obtained with it 2 years earlier (approximately 16 generations ago). Mortality was lower with the current generation (67%) than with the earlier generation (93%). However, with the latter generation, the mean parasite population size in beetles that survived to day 15 p.i. was significantly higher (14·1 cysticercoids/beetle) than in those infected with the recent generation (7·3–7·9) cysticercoids/beetle). These findings suggest that relatively high selection pressures have been applied byT. confusumtoH. citelli, thereby reducing the number of parasite lines with high infectivity and consequently improving host survivorship. The host also responded to artificial, directed selection for reduced cysticercoid number (heritability estimates of 0·30 ± 0·12 and 0·26 ± 0·12) and increased survival (heritability estimates of 0·28 ± 0·12 and 0·15 ± 0·083). The realized heritability was 0·37 for cysticercoid number and 0·17 for increased survival.
The appearance of bisporocystic oocysts of Eimeria maxima in drug-treated chicks
Authors: Norton C. C. , Joyner L. P.
Published: June 2009

A line of Eimeria maxima acquired resistance to Lerbek (a mixture of clopidol and methyl benzoquate) after serial passage against rising drug levels. Abnormal bisporocystic oocysts which appeared throughout this series were picked out individually and these produced infections in further groups of chicks. Serial passages of selected bisporocystic forms raised their proportion in oocyst yields to about 80% after 10–14 passages, but a few normal oocysts were still present.
Migration of the schistosomula of Schistosoma mansoni from skin to lungs
Authors: Miller Patricia , Wilson R. A.
Published: June 2009

The number of schistosomula recovered from abdominal skin declined exponentially with time after infection. However, this decline was shown to be an untrue reflection of the numbers present because of changes in recoverability on days subsequent to infection. Digestion of skin by the enzymes collagenase and hyaluronidase produced a small increase in the number of schistosomula recovered. The number of schistosomula present in abdominal skin and capable of reaching maturity was estimated by exciting the area to which cercariae had been applied, from groups of hosts at daily intervals after exposure. The number of worms maturing in each group of hosts was then determined. The mean duration of stay of schistosomula in mouse, hamster and rat abdominal skin was estimated at 88, 64·5 and 70 h, respectively. The fluid content of abdominal skin to which cercariae had been applied, increased following infection but it was concluded that this alone was not the predominant factor controlling exit of worms. The stimulation of a delayed hypersensitivity response not directed against schistosomes (in mice previously sensitized with 1-chloro,2–4-dinitrobenzene (DNB)) 1 day after exposure to cercariae, produced a significant increase in the number of schistosomula leaving the skin and reaching maturity. Schistosomula can be recovered from the axial lymph nodes of mice, hamsters and rats. If the schistosomula from mice are injected into the tail vein of uninfected mouse hosts, they have the same chance of maturing as comparable skin schistosomula. They are therefore apparently unharmed by their passage through the nodes. Interference with lymphatic drainage by surgical removal of lymph nodes has no effect on the number of schistosomula recovered from the lungs, but the peak recovery is delayed by 24 h. The hamster cheek-pouch, a site with no afferent lymphatic drainage, was also used to investigate the importance of the lymphatic exit route. There was no reduction in the number of adult worms recovered following infection at this site compared with the normal abdominal skin site. The migration of schistosomula to deeper tissues and their entry into blood vessels was followed using the cheek-pouch preparation. It was concluded that the major route of exit from the skin is the blood vascular system.
The oocyst sporulation time ofEimeriaspecies from the fowl
Authors: Norton C. C. , Chard M. J.
Published: June 2009

Freshly isolated oocysts were sporulated at 29°C with constant aeration. Minimum sporulation time was determined by dosing the developing oocysts at intervals of 1 h to successive groups of chickens to assess the first occurrence of infective forms. Microscopic analysis of the sporulating oocysts allowed calculation of the time required for 50% of the oocysts to complete the process. This was considered to be the most accurate determination and the most useful for comparative purposes. For 7 species of coccidia in the fowl, the 50% sporulation times were as follows:Eimeria acervulina11·4 h;E. brunetti38·3 h;E. maxima38·1 h;E. mivati19·0 h;E. necatrix19·7 h;E. praecox24·8 h;E. tenella21·2 h.
Stage-specific proteins of the avian malariaPlasmodium lophurae
Authors: Sherman I. W. , Tanigoshi Linda
Published: June 2009

The proteins in the soluble and membrane fractions ofPlasmodium lophurae, separated by SDS-PAGE and stained with Coomassie blue, were distinct from one another and different from the soluble and membrane proteins of the host cell, the duckling erythrocyte. Pulse-labelling of malaria-infected red cells containing schizonts or trophozoites with [14C]isoleucine, followed by parasite isolation, SDS-PAGE and autoradiography, showed a pattern of incorporation into soluble proteins identical to the banding pattern of gels stained with Coomassie blue. On autoradiograms, the banding patterns of the membrane proteins of trophozoites and schizonts labelled with [14C]isoleucine were similar. No qualitative differences in the soluble proteins of trophozoites and schizonts were apparent when isoleucine was used as the radiotracer; however, the banding pattern of membrane and soluble proteins labelled with [14C]isoleucine were distinct from each other. The banding pattern of soluble proteins, after staining with Coomassie blue, was distinctly different from the array of bands seen after autoradiography of parasites derived from infected cells pulse-labelled with [14C]histidine. Only small amounts of contaminating haemoglobin in the soluble protein fraction of parasites were labelled with histidine; the membrane fraction, on the other hand, had high incorporation into a single 43 kDalton band, the histidine-rich protein. No band differences, either in the membrane or soluble fractions, were observed in autoradiograms after pulse-labelling trophozoites and schizonts with [14C]histidine. The most consistent and distinct differences in protein synthesis were seen inP. lophuraepulse-labelled with [14C]proline. Autoradiograms of both soluble and membrane fractions showed the presence of bands unique to the trophozoite and schizont–stage-specific proteins.
The open-field behaviour of mice infected with Trichinella spiralis
Authors: Rau M. E.
Published: June 2009

The behaviour of mice exposed to graded doses of Trichinella spiralis larvae was monitored in an open-field situation. Ambulatory and exploratory activity declined significantly as the infections progressed, whereas the time spent inactive increased concomitantly. The advent of these behavioural changes coincided with the expected release of larvae by the adult worms and showed no clear signs of abating as late as 90 days post-inoculation. The levels of activity were negatively correlated with the inoculating dose. Such behavioural changes may render the host more vulnerable to predation and thus enhance parasite transmission.
Invasion of chicken caecal and intestinal lamina propria by crypt epithelial cells infected with coccidia
Authors: Fernando M. A. , Lawn A. M. , Rose M. Elaine , Al-Attar M. A.
Published: June 2009

The development of second generation schizonts ofEimeria necatrixandE. tenellawas studied with the electron microscope. Invasion of the crypt epithelial cells by merozoites of the first generation schizonts caused changes in the morphology of the infected cells and stimulated their migration into the lamina propria through breaks which appeared in the basement membrane of the crypts. Second generation schizonts developed in the lamina propria within these crypt cells whose epithelial origin was confirmed by their interconnection by desmosomes and tight junctions and by their possession of characteristic microvilli. A comparison is made between this invasion of the lamina propria by parasitized cells and invasion of connective tissue by malignant epithelial cells; the possible mechanisms involved are discussed.
Parasite-induced learned taste aversion involving Nippostrongylus in rats
Authors: Keymer Anne , Crompton D. W. T. , Sahakian B. J.
Published: June 2009

After demonstrating that rats were capable of discriminating between the same diet treated with either flavour 1 or flavour 2 and that the 2 flavours of diet were equipreferred, an experiment was carried out to see whether learned taste aversion might play a role in the reduction of food intake that is commonly observed during the course of a parasitic infection. The results showed that rats, given a subcutaneous inoculation of approximately 6000 third-stage larvae of Nippostrongylus brasiliensis (Nematoda) while feeding on a diet containing flavour 2, strongly preferred to eat diet containing flavour 1 when given simultaneous choice conditions. Uninfected rats showed no preference and ate equal amounts of both flavoured diets. This effect is interpreted as the first experimental demonstration of learned taste aversion using a eukaryotic parasite as the inductive agent.
Identification ofTheileriainfections in living salivary glands of ticks
Authors: Young A. S. , Leitch B. L. , Leitch B. L. , Stagg D. A. , Dolan T. T.
Published: June 2009

It was found that interference contrast microscopy gave good morphological differentiation of the living and intact salivary glands from adult ixodid ticks,Rhipicephalus appendiculatusandAmblyomrna variegatum, removed by dissection. In many cases the individual cell types of the acini could be recognized. When the salivary glands of infected adult ticks were examinedTheileriaparasites were detected.Theileria parva, T. taurotragiandT. mutanscould be detected in the salivary glands after they reached the mature secondary sporoblast stage achieved even in unfed ticks. Parasites were detected only in type III acini. The morphology of tertiary sporoblasts and sporozoites of theseTheileriaspp. was clearly recognized in feeding ticks. Sporozoites ofT. parvaproved to be infective to cattle and to peripheral blood leucocytes of cattlein vitroafter interference contrast examination. Interference contrast examination of living salivary glands was used for selection of salivary glands with high infections ofT. parvasporozoites and the sporozoites could be separated in large numbers from these salivary glands. Using this technique it appeared possible to cloneTheileriaparasites from salivary glands with 1 infected acinus.
Recent advances in our understanding of pentastomid reproductive biology
Authors: Riley J.
Published: June 2009

Pentastomids are arthropod parasites which attain maturity in the respiratory tracts of vertebrates. All pentastomids exhibit an obvious sexual dimorphism in that fully mature females are invariably much bigger than males. Unusually though, copulation, which happens only once in the lifetime of females, occurs when both sexes are approximately the same size and the uterus of the female is undeveloped. This is because sperm is stored in spermathecae which, being positioned at the junction of the oviduct and uterus, become more remote from the vagina as the uterus elongates during development. The provision of spermathecae for sperm storage allows oocytes, shed continuously from the ovary, to be fertilized from time to time. What renders this process quite remarkable, and possibly unique, is the extreme length of the patent period. In one species this can extend up to an estimated 10 years and is associated with an egg production of about 106eggs/female/year. Spermathecal structure provides some clues as to how prolonged sperm storage and the continuous fertilization of oocytes is accomplished. The upper region of the access duct is a narrow, chitinized tube which tapers to as little as 3 μm diameter at the point of entry into the spermatheca. The chitinous (?) lining of the spermatheca is relatively impermeable and apparently functions to totally isolate sperm from external influences: stored sperm are arranged in bundles and whorls and remain totally quiescent and inactive during the storage period. The entire spermatheca is invested by muscle fibres, the contraction of which will express small numbers of sperms through the narrow access duct. These are then reactivated by secretions from the female reproductive tract: the extreme narrowness of the spermathecal duct provides the fine adjustment of the system. The narrowness of the duct also creates problems during the process of insemination, since sperm discharged directly into the female reproductive tract would be unlikely to find the spermatheca through such a structure. Accordingly, the male cirrus is much modified to directly penetrate the spermathecal duct during copulation. Sperms, stored in the male seminal vesicle, are apparently activated prior to sperm transfer, and swim along the cirrus to be guided directly into the spermathecal lumen. Some unusual variations on the normal pentastomid life-cycle are discussed.
Different levels of immunity to Schistosoma mansoni in the mouse: the role of variant cercariae
Authors: Smith M. A , Clegg J. A.
Published: June 2009

Very variable levels of immunity to a second infection with Schistosoma mansoni were recorded in 7 strains of mice, 12–15 weeks following a small primary infection. When 2 or more strains of mice were assayed at the same time, less variation occurred within the experiment than between different experiments. This evidence suggested variation between pools of cercariae as the main cause of variability in immunity. In direct experiments in one strain of mouse, 2 different pools of cercariae stimulated widely different levels of immunity to the same challenge. Conversely, challenge infections drawn from different pools showed different susceptibility to immunity stimulated by the same primary infection. Individual clones of cercariae, from snails infected with single miracidia, showed a high level of susceptibility to immunity stimulated by a small bisexual infection, or were not susceptible at all. Antigenic polymorphism is the most likely explanation for the differences observed between clones of cercariae. However, indirect immunofluorescence showed the presence of at least 1 common antigen on the surface of schistosomula derived from different clones of cercariae and clone-specific antigens have not been detected.
Evasion of the haemocytic defence reaction of certain insects by larvae of Hymenolepis diminuta (Cestoda)
Authors: Lackie Ann M.
Published: June 2009

Larvae of Hymenolepis diminuta develop in the haemocoele of the beetles Tribolium and Tenebrio, and of the locust Schistocerca gregaria, without being encapsulated by haemocytes. The mechanism of this evasion of the haemocytic defence reaction has been examined using various techniques. Larvae grown in culture and injected into S. gregaria have few or no haemocytes adherent even after 8 h, although latex beads injected at the same time have been thickly encapsulated. This, and results of transplanting cysticercoids and host tissue between different insect species, suggests that the surface of the larvae may bear an inherent similarity to the surface of host tissues and thus escape recognition as ‘not-self’ by the host’s haemocytes.
Micromotility meter: an instrument designed to evaluate the action of drugs on motility of larval and adult nematodes
Authors: Bennett J. L. , Pax R. A.
Published: June 2009

An instrument for measuring the motility of larval and adult nematodes is described along with an analysis of its use as a tool to analyse drug action on these parasites. Motility was detected from larval parasites ofNippostrongylus brasiliensisandAscaris suumin the absence and presence of various anti-nematodal drugs. These agents produced, within 48 h, a significant decrease in larval parasite motility. The instrument was also capable of detecting the motility ofCaenorhabditis elegans, adult femaleBrugia pahangiand their response to anti-nematodal drugs. The design of the instrument allows us to accurately measure motility in a single sample within 60 sec.
Parasite–host relationships during the development of Eimeria dispersa Tyzzer 1929, in the turkey (Meleagris gallopavo gallopavo) with a description of intestinal intra-epithelial leucocytes
Authors: Millard B. J. , Lawn A. M.
Published: June 2009

An electron microscopical study was made on the development of Eimeria dispersa in the small intestine of the domestic turkey. Turkey poults, 10–14 days of age, were inoculated with oocysts and pieces of intestinal tissue were fixed at intervals between 3·5 and 114 h after inoculation. Sporozoites were occasionally seen in enterocytes but more often in ‘pale’ cells closely resembling lymphocytes. These cells were insinuated between enterocytes and in this study are referred to as intestinal intra-epithelial leucocytes (IEL). Maturation of the first-generation of schizogony occurred in this type of cell. Other generations of schizonts and gametogony occurred in epithelial cells and were characterized by the presence of ‘spines’ arranged around the parasitophorous vacuole extending into the cytoplasm of the host cell. A limited study of the parasite in the Bobwhite quail, Colinis virginianus, showed that development occurred in similar cells to those of the turkey. The ‘spines’, which were characteristic of later stages of E. dispersa in the turkey, were also present in this host and seemed to be a characteristic of E. dispersa, not of the host species.
Effect of low temperature on development of the coccidium Eimeria funduli in the Gulf killifish
Authors: Solangi M. A. , Overstreet R. M. , Fournie J. W.
Published: June 2009

Eimeria funduli, a coccidium infecting the liver and pancreas of killifishes and requiring an intermediate host, was allowed to develop at 22±2 °C for 5, 10, 15 or 20 days (schizont through zygote stages) in Fundulus grandis and was then exposed to 10·0±0·5 °C for 20 days or to 7·0±0·5 °C for 5 or 20 days. Both low temperature treatments inhibited all developmental stages, except for the case of fish infected for 5 days before exposure to 7 °C in which infections were eliminated. Returning fish back to a temperature of 22 °C for 20 days resulted in resumed development of all stages at the same or somewhat reduced rate. In all cases, intensity of infections was greatly reduced during exposure to low temperatures. Many organisms exhibited abnormalities. Gamonts and zygotes were atrophied or disintegrated within their parasitophorous vacuoles in all exposures and, in fish exposed to 7 °C for 20 but not 5 days, about 30% of the oocysts were abnormal, with from 1–8 sporoblasts. Areas of degeneration or necrosis incorporated aggregates and single parasites in both the pancreas and the hepatic parenchyma. The granulocytic inflammatory response, which at 22 °C was normally restricted to the period spanning development of gamonts and formation of the oocyst wall, was inhibited or delayed from infiltrating infected, diseased areas at low temperatures. The response intensified after cold-exposed fish were returned to 22 °C. A fibroid, non-granulocytic response occurred in fish introduced 5 days post-infection to 10°C before being returned to warm water. Two other types of lesion occurred in the pancreas. The first could develop into necrosis and was associated with low temperature; it did not always involve infected tissue. The other, a degenerating focal alteration, was not necessarily associated with infections or low temperatures.
Passive immunization of mice againstSchistosoma mansoniwith an IgM monoclonal antibody
Authors: Smith M. A. , Clegg J. A. , Snary D. , Trejdosiewicz A. J.
Published: June 2009

Two hybridomas secreting monoclonal IgM antibody toSchistosoma mansonihave been isolated following fusion of spleen cells from Balb/c mice immunized with livingS. mansoniand NS1 myeloma cells. One monoclonal IgM antibody (WP66.4) mediated about the same level of passive protection against a challenge infection as immune serum from mice with a chronicS. mansoniinfection. The other monoclonal antibody (WP66.2) did not give a significant level of passive protection. This result indicates that the effective monoclonal antibody recognizes an antigen which may be a valuable candidate for experimental vaccination.In vitroone monoclonal antibody (WP66.4) caused a much higher level of complement-dependent cytotoxicity than the other (WP66.2), suggesting a possible mechanism for the effect observedin vivo. With indirect immunofluorescence both monoclonal antibodies reacted with surface determinants on livingS. mansonischistosomula, adult worms and miracidia but these determinants were not detected on cercariae or lung schistosomula. Neither monoclonal antibody cross-reacted withS. haematobiumschistosomula orFasciola hepaticametacercariae, indicating a possible use for these reagents in differential diagnosis ofS. mansoniinfections.
The effect of worm, age, weight and number in the infection on the absorption of glucose by Hymenolepis diminuta
Authors: Henderson D.
Published: June 2009

In Hymenolepis diminuta the in vitro rate of absorption of glucose/unit dry weight of worm falls with increasing worm age, with increasing worm weight and as the number of worms in an infection is increased. In a 6 mM solution of glucose, a 5 mg (dry weight) worm from a 7 or 8 worm infection absorbed 80 µmoles/g dry weight/5 min whereas a 60 mg worm, also from a 7 or 8 worm infection, absorbed only 35µmoles/g dry weight/5 min. This change in the rate of absorption is, at least partly, thought to be due to changes in the relative surface area: weight ratio during growth of the worm.

The kinetic parameter, Kt glucose, increased from 1.1 mM for a 5 mg (dry weight) worm from a 7 or 8 worm infection to 2 mM for a 60 mg worm. This change in the functioning of the glucose transport system may indicate that there are two components of the glucose transport system – or two separate systems – one with a low Kt and one with a high Kt, the ratios of which change during worm growth.

The smaller the number of worms in an infection the greater the rate of glucose absorption. Using 8–day–old worms in a 6 mM glucose solution, 1 worm from a single worm infection absorbs 111 μmoles/g dry weight/5 min, 1 worm from a 7 or 8 worm infection absorbs 88 μmoles/g dry weight/5 min and 1 worm from a 45–50 worm infection absorbs 77 μmoles/g dry weight/5min. The significance of this is discussed with reference to the ‘crowding effect’ in tapeworms.
Host restriction, morphology and isoenzymes among trypanosomes of some British freshwater fishes
Authors: Letch C. A.
Published: June 2009

Trypanosomes were studied from the blood of 6 species of small British fish caught in the River Lee. Morphologically the trypanosomes from the blood ofNemacheilus barbatulusL.,Phoxinus phoxinusL.,Cottus gobioL.,Gobio gobioL.,Gasterosteus aculeatusandPungitus pungitusL. were indistinguishable. Cross-transmission experiments using syringe passage of culture forms and also the leech vectorHemiclepsis marginatashowed that the trypanosomes were not host specific. The isoenzyme patterns of culture forms fromN. barbatulusandP. phoxinuswere identical for 11 enzymes studied. The trypanosomes from the 6 species of fish previously classified as separate species are, on the basis of these results, regarded as a single species,Trypanosoma cobitis(Mitrophanow, 1883).
Lizard malaria: cost to vertebrate host's reproductive success
Authors: Schall J. J.
Published: June 2009

Plasmodium mexicanum is a common malarial parasite of the western fence lizard, Sceloporus occidentalis, in northern California, USA. Infected female lizards store substantially less fat during the summer activity season and produce smaller clutches of eggs than do non-infected animals. Stored fat is utilized in the production of eggs; the energy content of the decrement in stored fat is approximately equal to the energy content of the average reduction in number of eggs. Thus, there is ongoing strong selective pressure on the host to evolve appropriate anti-parasite measures.
The nutritional physiology of Trichoplusia ni parasitized by the insect parasite, Hyposoter exiguae, and the effects of parallel-feeding
Authors: Thompson S. N.
Published: June 2009

Host nutrition plays a major role in the nutritional physiology of Trichoplusia ni parasitized by the hymenopterous insect parasite, Hyposoter exiguae. Severely reduced growth rate characterized the host association throughout the 4th developmental stadium. This effect of parasitization, however, was indirect and growth depression of parasitized larvae was entirely accounted for by the accompanying decreased rate of food consumption. Parallel-fed larvae, that is, unparasitized larvae feeding on nutrients at the same rate as observed in ad libitum-fed parasitized individuals, displayed lower rates of growth than parasitized larvae and the latter had higher rates of assimilation. Parasitization, therefore, directly resulted in an increased rate of assimilation over that observed in uninfected insects after accounting for the effects of altered food consumption. Similarly, differences in the pattern of response to decreased dietary protein levels between parasitized and unparasitized insects could be explained on the basis of differences in their rates of food consumption
Schistosoma mansoni: the structure and elemental composition of pre-acetabular penetration gland cell secretion in pre-emergent cercariae
Authors: Davies T. W.
Published: June 2009

The structure and elemental composition of the secretory products of the pre-acetabular penetration gland cells of pre-emergent cercariae of Schistosoma mansoni have been investigated at an ultrastructural level using X-ray probe microanalysis. The secretion contains 2 types of bodies, one homogeneous and one heterogeneous with electron-lucent areas. Using a variety of fixation and sectioning techniques it has been shown that the apparent electron density of the homogeneous bodies (Type B) is the result of interaction with osmium tetroxide and stain. The small electron-lucent areas of the other type of secretory body (Type A) represent regions where granules have been leached out by processing media. X-ray analysis of cercariae still within sporocysts has indicated that these granules are very rich in calcium, and it is suggested that the calcium is absorbed by the developing cercariae through the sporocyst wall from the molluscan haemolymph.
The ultrastructure of the fore-gut of the redia of Parorchis acanthus Nicoll (Digenea: Philophthalmidae) from the digestive gland of Nucella lapillus L
Authors: Rees F. Gwendolen
Published: June 2009

The fore-gut of the redia of Parorchis acanthus is ingestive in function. It consists of a buccal cavity, suctorial pharynx and an oesophagus divided into anterior and posterior regions. The syncytial lining is continuous with that covering the body surface, except for the posterior region of the oesophagus which is lined by a separate syncytium. This latter has different cytoplasmic inclusions and the unusual feature of a single ventral nucleus in the outer cytoplasmic epidermis. Intrinsic and extrinsic muscles are responsible, respectively, for the fairly rapid passage of food through the fore-gut and for support. Secretion bodies in the epidermis are probably discharged into the lumen and pass with food into the intestine where they may be involved in extracellular digestion. Young rediae feed mainly by mouth while older, immotile rediae absorb nutrients mainly through the body surface.
Experimental studies on the transmission dynamics of the cercariae of Echinoparyphium recurvatum (Digenea: Echinostomatidae)
Authors: Evans N. A. , Gordon D. M.
Published: June 2009

Age-dependent survival and infectivity characteristics are described for the cercariae of Echinoparyphium recurvatum. At 18 °C the maximum life-span of the cercariae was 48 h and 50% survival occurred at 30·5 h. Infectivity of cercariae to the second intermediate host, Lymnaea peregra was maximal approximately 2 h after emission from the first intermediate host and it subsequently declined to zero at 19 h. It is suggested that the period of sub-maximal infectivity at the beginning of the cercarial life-span may represent a phase during which dispersal is an important function of the larvae. The relationship between infective stage density and establishment success was linear up to densities equivalent to 5000 cercariae/1. At higher cercarial densities the proportion of parasites establishing in second intermediate hosts declined progressively with increasing cercarial density. The mean number of parasites establishing/host increased linearly with increasing host size.
Mitochondrial adenosine triphosphatase activity and temperature adaptation inSchistocephalus solidus(Cestoda: Pseudophyllidea)
Authors: Walker R. W. , Barrett J.
Published: June 2009

During its life-cycle, the cestodeSchistocephalus solidusis parasitic in both an ectotherm (Gasterosteus aculeatus) and an endotherm (Gallus domesticus) host, and so provides an excellent model with which to study temperature adaptation in parasites. A mitochondrial fraction was prepared from the adults and plerocercoids ofS. solidusand from their respective hosts; the activities of the mitochondrial adenosine triphosphatase (ATPase) were then measured over the temperature range 1–45 °C. The plerocercoids ofS. solidusshow evidence of immediate temperature compensation; this would provide a mechanism for withstanding the abrupt temperature change experienced during infection of the final host. Analysis of the Michaelis constant data suggests that variation of Km, awith temperature may be a major factor in this immediate temperature compensation. In response to acclimation at 5 and 19°C, plerocercoid ATPase showed inverse or paradoxical rate compensation, as did the enzyme from the fish host. Acclimation at the two temperatures had no effect on the Q10or on the linearity of the Arrhenius plots for the plerocercoid mitochondrial ATPase and only a small effect on the Km a. Acclimation of the fish host again had only a small effect on the Km, aof the fish mitochondrial ATPase but, in contrast to the plerocercoid, there was also a significant effect on the Q10and the Arrhenius plots. AdultS. solidusATPase showed partial rate compensation and had a biphasic Arrhenius plot, suggesting that after infection there had been a change in the enzyme or its micro-environment. In terms of the effect of temperature on the Q10amd Km, aand in the biphasic nature of the Arrhenius plot, the mitochondrial ATPase of adultS. solidusshowed similarities with the enzyme from its bird host.