bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host-finding in Trichobilharzia ocellata cercariae: swimming and attachment to the host
Authors: Feiler W. , Haas W. 
Published: June 2009

SUMMARYThe cercaria of Trichobilharzia ocellata finds and identifies its duck host with a seriesof different behavioural phases. Dispersal and selection of the water surface as microhabitat is achieved by an intermittent swimming behaviour, which is governed by the interplay of passive dropping with forward and backward swimming movements and includes a positive phototactic and a geonegative orientation. Then the cercariae tend to cling to the water surface in an energy-saving resting position. A movement towards the duck feet as the site of entry occurs when shadows evoke forward swimming movements, which are directed away from the source of light, i.e. normally downwards. Forward swimming movements are also stimulated by touch, but only in free-swimming cercariae and not when these are in the resting position. Attachments occur only when a substrate is touched during forward swimming movements. Attachments are stimulated by warm substrates (1 °C temperature difference triggers a nearly maximal response) and by chemical components of duck-foot skin, and the readiness to attach is increased when the forward swimming movement is started by shadow stimuli.
The effects of H-2 and non-H-2 genes on the expulsion of the nematode Trichuris muris from inbred and congenic mice
Authors: Else Kathryn , Wakelin D. 
Published: June 2009

SUMMARYTwo groups of H-2 congenic strains of mice were compared for their susceptibility to a primary infection with the nematode Trichuris muris. Mice of the BALB genetic background were markedly more resistant than mice of the BIO genetic background, as reflected by the rate of expulsion of T. muris from the large intestine. Within each of the two groups of H-2 congenic strains mice possessing the H-2k haplotype (BALB/k, B10.BR) were more susceptible to infection than mice expressing other haplotypes; B10 background strains expressing H-2b (B10) or H-2q (B10.G) alleles were the most resistant of the four congenic strains studied. Differential resistance was observed within three of the four BIO congenic strains and this is discussed in terms of rate of development of the protective immune response in relation to worm development. The results support the conclusion that both H-2-linked and non-H-2 genes play important roles in controlling the immune response which expels worms from the gut.
Continuous cultivation of intraerythrocytic Plasmodium falciparum in a serum-free medium with the use of a growth-promoting factor
Authors: Asahi H. , Kanazawa T. 
Published: June 2009

SUMMARYSerum-free media were used to culture Plasmodium falciparum. A commercial preparation, Daigo's GF21 developed as a growth-promoting factor for many kinds of mammalian cells, and consisting of the 55–70% ammonium sulphate fraction of adult bovine serum, insulin, transferrin, ethanolamine and sodium selenite, was found to sustain growth of the parasite when Daigo's T was employed as a basal medium. The optimal Daigo's GF21 concentration for parasite growth was between 5 and 20% (v/v), with the best results at 10%. Differential counts indicated that Daigo's GF21 is essential for schizogony. Established serum-free medium, GIT, consisting of Daigo's T basal medium and Daigo's GF21, yielded good parasite growth without any supplementation. Growth-promoting factor derived from adult bovine serum in Daigo's GF21 was shown to be crucial to parasite growth. The results presented here will not only be of practical value, but will provide important information about the developmental requirements for the parasite.
Characterization of the modes of action of anti-Pbs21 malaria transmission-blocking immunity: ookinete to oocyst differentiationin vivo
Authors: Ranawaka G. R. R. , Fleck S. L. , Alejo Blanco A. R. , Sinden R. E. 
Published: June 2009

SUMMARYThe impact of immune sera, and peripheral blood cells (PBC) from mice immunized withPlasmodium bergheiookinetes; and of purified immunoglobulin or Fab fragments from anti-Pbs21 monoclonal antibody 13.1, upon establishment of oocyst infections in the mosquito was studied. Infections were initiated either from gametocyte-infected mice, or membrane feeders which contained either gametocytes or mature ookinetes. PBC from ookinete-immunized mice presented with non-immune serum failed to show any transmission-blocking activity. Anti-ookinete serum, intact anti-Pbs21 monoclonal antibody 13.1 or its Fab fragments, all inhibited oocyst formation significantly. When gametocyte-infected mice or gametocytes in membrane feeds were used, inhibition did not directly correlate with antibody concentration. In membrane feeders that contained ookinetes and antibody, concentration-dependent inhibition usually occurred. The efficacy of purified 13.1 IgG was dependent upon the ookinete concentration. The ookinete plasmalemma and cytoplasm were significantly disturbed after 12h in bloodmeals that contained antibody 13.1, but not in the isotype controls. These changes may have caused the observed failure of the ookinete to migrate as rapidly as the controls from the destructive environment of the bloodmeal.
Platyhelminth FMRFamide-related peptides (FaRPs) contract Schistosoma mansoni (Trematoda: Digenea) muscle fibres in vitro
Authors: Day T. A. , Maule A. G. , Shaw C. , Halton D. W. , Moore S. , Bennett J. L. , Pax R. A. 
Published: June 2009

SUMMARYMolluscan FMRFamide and two recently discovered platyhelminth FMRFamide-related peptides (FaRPs), GNFFRFamide from the cestode Moniezia expansa and RYIRFamide from the terrestrial turbellarian Artioposthia triangulata, cause dose-dependent contractions of individual muscle fibres from Schistosoma mansoni in vitro. The most potent FaRP tested was the turbellarian peptide RYIRFamide, which produced a concentration-dependent effect between 10−9 and 10−7 M. FMRFamide and GNFFRFamide were less potent, inducing contractions between 10−8–10−6 M and 10−7–10−5 M respectively. The contractile effect of each of these peptides was blocked by the presence of 1 µM FMR-DFamide. FMRF free acid did not elicit contraction of the muscle fibres. The FaRP-induced contractions did not occur if the Ca2+ was omitted and 0·5 µM EGTA was added to the extracellular medium. The FaRP-induced contractions were not blocked by the Ca2+ channel blockers nicardipine, verapamil or diltiazem, although high K+-induced contractions of these fibres were blocked by nicardipine. These data indicate the presence of FaRP receptors on schistosome muscle fibres and demonstrate their ability to mediate muscle contraction. The action of these endogenous flatworm peptides on schistosome muscle is the first demonstration of a direct excitatory effect of any putative neurotransmitter on the muscle of a flatworm, and establishes a role for FaRPs in neuromuscular transmission in trematodes. In addition, it provides the first evidence that the peptidergic nervous system is a rational target for chemotherapeutic attack in parasitic platyhelmiths.
Amino acid catabolism in the nematodesHeligmosomoides polygyrusandPanagrellus redivivus. 1. Removal of the amino group
Authors: Grantham Barbara D. , Barrett J. 
Published: June 2009

SUMMARYThe major transaminase inHeligmosomoides polygyrus, Panagrellus redivivusand rat liver was the 2-oxoglutarate-glutamate system, with relatively few amino acids acting as donors for the pyruvate-alanine and oxaloacetate–aspartate systems. The relative effectiveness of the different amino acid donors in the three transaminase systems was similar in all three tissues. BothH. polygyrusandP. redivivuscan oxidatively deaminate a range of L-amino acids, although D-amino acid oxidase activity was low. Serine and threonine dehydratase activity and histidase activity were present inH. polygyrusandP. redivivusand both nematodes were also able to deaminate glutamine, asparagine and arginine. When NAD(H) was the cofactor the glutamate dehydrogenases ofH. polygyrusandP. redivivusshowed similar regulatory properties to the mammalian enzyme. However, with NADP(H) the results were anomalous. The capacity of both nematodes to transaminate and oxidatively deaminate amino acids was broadly similar and comparable to mammalian tissue. Glutamate dehydrogenase is probably the major route for deamination in these nematodes. A complete sequence of urea cycle enzymes could not be demonstrated in eitherP. redivivusorH. polygyrus.
The influence of Blastocrithidia triatomae (Trypanosomatidae) on the reduviid bug Triatoma infestans: in vivo and in vitro diuresis and production of diuretic hormone
Authors: Schnitker Antonia , Schaub G. A. , Maddrell S. H. P. 
Published: June 2009

SUMMARYThe homoxenous flagellate Blastocrithidia triatomae disturbs excretion in Triatoma infestans. During the first 4 and 24 h after feeding, infected 5th instars excreted approximately a 2·5-fold smaller volume of urine. Consequently, about double the normal volume of haemolymph could be obtained from these infected bugs 24 h after feeding. Surprisingly, the in vitro secretion rates of Malpighian tubules from uninfected and infected bugs were nearly identical. In addition, the storage and release of diuretic hormone in infected bugs was sufficient to induce normal secretion rates by isolated Malpighian tubules. Therefore, the previously observed ultrastructural alterations in the upper Malpighian tubules of infected bugs do not result in a disturbed in vitro secretion, although in vivo excretion is reduced.
Susceptibility of goats to tsetse-transmitted challenge withTrypanosoma vivaxfrom East and West Africa
Authors: Vos G. J. , Moloo S. K. , Gardiner P. R. 
Published: June 2009

SUMMARYTo determine if, as is the case withTrypanosoma bruceiandT. congolense, serodemes ofT. vivaxcould be distinguished on the basis of immunity to the metacyclic stages of the parasite, attempts were made to immunize goats by infection with infected tsetse, followed by chemotherapy or eventual ‘self-cure’. Thirty goats were infected by tsetse with either clones or stocks ofT. vivaxfrom East or West Africa. Twenty-four goats were treated with diminazene aceturate (Berenil, Hoechst A.G.) 2–6 weeks after infection and 6 goats were allowed to self-cure. Infection, followed by treatment, induced immunity to a first homologous challenge by infected tsetse in only 2 of 24 goats (one immune to the East African stock, and the other to a clone of the West African stock). Immunity to a clone of the East African stock was induced in 3 or 4 animals after a second infection and treatment and in the fourth animal of the group following a third infection and treatment. One of 2 goats infected with the clone of the East African stock was immune to challenge at 16 weeks, following self-cure without treatment, and 1 of 4 goats infected with the parent stock was similarly immune when challenged at 40 weeks post-infection. Goats susceptible to infection with East AfricanT. vivaxshowed evidence of partial immunity by delayed pre-patent periods and depressed parasitaemias after challenge. Goats infected with the relatively more virulent West AfricanT. vivaxwere, however, completely susceptible to infection after homologous challenge, and showed only a slight delay in pre-patent period. A similar result was obtained in a further 8 goats primed and challenged by large numbers of tsetse (20 or 100 infected tsetse/goat) with the West AfricanT. vivax. In further experiments using a very short treatment interval, infections following challenge were clearly shown to be the result of a lack of immunity rather than relapse following treatment. Lytic antibody activity to cultured metacyclic trypanosomes could not be detected during infection but such activity against bloodstream forms was detected after 2 weeks of infection. It is suggested that the primary reason for the erratic induction of immunity toT. vivaxemploying this methodology is the low number of metacyclics transmitted by infected tsetse, and thus poor antigenic stimulus encountered by goats upon tsetse challenge.
Characterization of two species ofLepeophtheirus(Copepoda, Caligidae) from flatfishes. Description ofLepeophtheirus europaensissp. nov
Authors: Zeddam J.-L. , Berrebi P. , Renaud F. , Raibaut A. , Gabrion C. 
Published: June 2009

SUMMARYIn the eastern Mediterranean, the copepodLepeophtheirus thompsoniBaird, 1850, has been reported to infest turbot, brill and flounder. By combining several methods, including enzyme electrophoresis, we show that this species is found only in turbot. By contrast, brill and flounder are infested by a species ofLepeophtheirusthat corresponds to no other species reported in the literature. We propose that the species be designated asL. europaensisand we describe the characteristics of the gravid female. This study was extended to the Atlantic populations of flatfishes and includes an investigation ofL. pectoralis(Muller, 1776), which infects flounder in the North Sea; we also confirmed the presence ofL. thompsoni(Baird, 1850) over the whole geographic range of turbot. Lastly, we discuss the specificity and distribution of these species along the European coasts.
A model of tsetse-transmitted animal trypanosomiasis
Authors: Milligan P. J. M. , Baker R. D. 
Published: June 2009

SUMMARYThe data needed to develop analytical models of trypanosomiasis transmission have become available only recently. By making some simplifying assumptions, models of the dynamics of the disease in vector, cattle and wild mammal populations can be constructed in order to determine criteria for successful disease control by mass and targetted chemotherapy, and by vector control. The heterogeneity in transmission due to tsetse fly feeding preferences and the variability of immunological characteristics among the vertebrate hosts account for differences in prevalence ofTrypanosoma vivaxandT. congolense, and also lead to an increase in the basic reproductive rates of the parasites and a corresponding decrease in the vector population density threshold for disease eradication or persistence. The long life-span of the vectors relative to the duration of the parasites' developmental period lead to high infection rates in the vector and high values of R0. The efficacy of chemotherapeutic regimes depends on the relationship between treatment rate and the duration of prophylaxis conferred by the drugs used. The model's predictions of the effects of vector control are shown to be in broad agreement with published field data for Mkwaja Ranch, Tanzania. Vector control programmes are frequently blighted by reinvasion, and the implications of this are discussed in terms of a model for fly immigration. With immigration of vectors, the disease is always endemic, though the infection rate in the fly population is modified by the effect of differential mortalities inside and outside the controlled area on cohorts of incubating flies. Sensitivity analysis of the model, using Monte-Carlo methods, enables an assessment of the relative importance of the parameters to be made. The results emphasize the need for studies of the wild animal reservoir to be carried out alongside entomological surveys. The relative accuracy with which field measurements need to be made in order to minimize the uncertainty in predictions of trypanosomiasis prevalence is discussed.
Decreased predator avoidance in parasitized mice: neuromodulatory correlates
Authors: Kavaliers M. , Colwell D. D. 
Published: June 2009

SUMMARYAlthough parasites are reported to alter host responses to predators, little is known about the neurochemical mechanisms involved. Using an odour preference test, we examined the effects of an acute, subclinical infection with the naturally occurring, single host, enteric protozoan parasite, Eimeria vermiformis, on the responses of male laboratory mice, Mus musculus, to a predator. Uninfected mice avoided the odour of a predatory cat, spending a minimal amount of time in a Y-maze in the vicinity of the cat odour. In contrast, mice infected with E. vermiformis, spent a significantly greater amount of time in the proximity of the cat odour, showing a reduced avoidance of the cat odour and a reduction in predator-induced fear or anxiety. This was not related to augmented opioid activity and decreased pain sensitivity in the infected mice, as neither treatment with the exogenous opiate, morphine, nor restraint stress-induced augmentation of endogenous opioid activity, had any significant effects on the responses of uninfected mice to cat odour. The altered responses of the infected mice to the cat odour were reduced by peripheral administration of the gamma-aminobutyric A (GABAA) antagonists, bicuculline and picrotoxin, but were not significantly affected by either the benzodiazepine antagonist, Ro 15–1788, the opiate antagonist, naloxone, or the excitatory amino acid, N-methyl-D-aspartate (NMDA) antagonist, MK-801. These results indicate that infection with E. vermiformis in mice reduces the avoidance of predator odour through neurochemical systems associated with anxiety involving, at least in part, GABAA receptor mechanisms.
Replication, differentiation, growth and the virulence ofTrypanosoma bruceiinfections
Authors: Turner C. M. R. , Aslam N. , Dye C. 
Published: June 2009

SUMMARYThis study had 2 objectives: first, to investigate how the processes of slender form replication, of differentiation from dividing slender to non-dividing stumpy forms, and of stumpy mortality, combine to determine the initial (acute-phase) growth rate ofTrypanosoma bruceipopulations; second, to determine how acute-phase growth rates influence parasite densities during the subsequent, chronic phase of infection. During the acute phase, slender and stumpy populations both grew approximately exponentially, the latter more slowly than the former. Mathematical models showed how this difference in slender and stumpy growth rates can be explained in terms of heterogeneous replication and differentiation rates. Stumpy life-expectancy was determined for one stock and found to be age-dependent with a half-life of 48–72 h, much larger than observed population doubling times of 5–10 h. A comparison of cloned stocks showed that the highest parasite densities during the chronic phase were associated with the highest acute-phase growth rates of both the whole parasite population and of the subpopulation of slender forms. By contrast, high chronic-phase parasitaemias artificially produced following rapid syringe passage were associated with low acute-phase growth rates of slender forms. Syringe-passaging is a laboratory procedure which selects for virulent parasites, but these parasites behave differently from naturally virulent stocks.
Investigation of the chemosensory function of amphids of Syngamus trachea using electrophysiological techniques
Authors: Riga E. , Perry R. N. , Barrett J. , Johnston M. R. L. 
Published: June 2009

SUMMARYSyngamus trachea, the gape nematode, has been used as a model to study the chemosensory function of amphids. Extracellular electrophysiological recordings were performed directly on amphids. The amphids were stimulated by blood serum from a host bird and by D-tryptophan. The spike frequency produced by the amphid increased significantly after the application of the serum and the application of D-tryptophan. Two types of amphidial neurones responded to the presence of the stimuli. These extracellular recordings have verified the chemosensory function of the amphids.
Isolates of Trichuris muris vary in their ability to elicit protective immune responses to infection in mice
Authors: Bellaby T. , Robinson K. , Wakelin D. , Behnke J. M. 
Published: June 2009

SUMMARYMuch of what is currently known of the host-parasite interaction between mice and the parasitic nematode Trichuris muris has come from experiments using a single parasite isolate (E/N). This isolate has been compared with 2 others which, on morphological criteria, belong to the same species. In 3 inbred strains of mouse that show distinct, genetically determined response phenotypes, there was a consistent pattern in terms of parasite survival time regardless of host strain, E/K worms being expelled early, E/N expelled later and S worms very late or not at all. High-responder CBA mice expelled E/K and E/N worms earlier than low-responder C57 B1/10 mice. B10.BR mice were permissive to S isolate infection, mounted a very late response to E/N worms but expelled E/K worms effectively by day 25. The differential response of mice to these isolates provides an experimental system for identifying the basis of variation in this host-parasite relationship.
A new species of Cotugnia (Cestoda Davaineidae) from the domestic pigeon in India
Authors: Malviya H.C. , Dutt S.C. 
Published: June 2009

Cotugnia columbae sp.nov. from the domestic pigeon is described and compared with other species of the genus. The tapeworm measures 108–130 mm in length and 2·236 mm in maximum breadth. The rostellum bears 200 hooks, 7·7–10·6 μm. long arranged in two rows. Testes number 105–130 and the cirrus pouch measures 0·354–0·376 x 0·054–0·065 mm.We are grateful to Dr C. M. Singh, Director, Indian Veterinary Research Institute, and to Dr H. D. Srivastava, erstwhile Assistant Director and Head of the Division of Parasitology, for their interest in these studies and for the provision of the necesssary facilities.
Sporulation of Amblyospora (Microspora) in female Culex salinarius: induction by 20-hydroxyecdysone
Authors: Lord J. C. , Hall D. W. 
Published: June 2009

SummaryAmblyospora sp. is a microsporidian parasite which is transovarially transmitted from an infected female Culex salinarius to her progeny. This transmission is dependent on synchronization of sporulation of the parasite and ovarian development of the host, both of which are initiated when the mosquito takes a blood meal. We induced sporulation in the absence of a blood meal and, with or without prior ovariectomy, by injection of 20-hydroxyecdysone, a hormone whose precursor, ecdysone, is produced by the ovaries of blood-fed mosquitoes. Sporulation in response to a blood meal was prevented by ovariectomy of the host prior to blood feeding or by decapitation immediately after feeding.
The tissue response of Yellow Perch, Perca flavescens Mitchill to infections with the metacercarial cyst of Apophallus brevis Ransom, 1920
Authors: Pike A. W. , Burt M. D. B. 
Published: June 2009

SummaryApophallus brevis metacercariae localize in parasite-produced cysts mainly in the myotomes of Perca flavescens. The host response induced by this parasite is very intense and leads to the formation of an elaborate host-formed capsule of material which is very similar if not identical to host bone. This capsule is pierced by two canals situated at opposite poles in the cyst and enables the parasite to escape from this host capsule on being ingested by a definitive host. Successive layers of melanocytes and connective tissue, containing lipid droplets, are also present around the bony capsule. Histochemically this bony capsule and the fish bone are virtually identical but there are slight organizational differences in the capsule tissues compared to the fish bone. It is postulated that the formation and arrangement of the capsule may be influenced by the parasite and may not therefore be a defensive development by the host.
An automated large-scale culture system of Plasmodium falciparum using tangential flow filtration for medium change
Authors: Ponnudurai T. , Lensen A. H. W. , Meuwissen J. H. E. Th. 
Published: June 2009

SummaryAsexual stages and mature gametocytes of Plasmodium falciparum have been produced in a 500 ml suspension culture system containing 6–10% red cells. Medium change was automated and was accomplished using a tangential flow filtration unit. The rate of multiplication of the parasite (isolate NF 54) was consistently high when compared with static cultures and ranged from 6·4 × to 15·3 × per cycle in 8 experiments. Mature gametocytes were present in up to 2% of red cells in 14-day-old cultures. Only minor modifications would be required to further scale-up the volume of the culture.