bluuebunny/crossref_metadata_2025_split huggingface dataset:
GABA in the nervous system of parasitic flatworms
Authors: Eriksson K. S. , Maule A. G. , Halton D. W. , Panula P. A. J. , Shaw C. 
Published: June 2009

SUMMARYIn an immunocytochemical study, using an antiserum and a monoclonal antibody specific for the amino acid, γ-aminobutyric acid (GABA), GABA-like immunoreactivity (GLIR) has been demonstrated for the first time in parasitic flatworms. In Moniezia expansa (Cestoda), GLIR was seen in nerve nets which were closely associated with the body wall musculature and in the longitudinal nerve cords. In the liver fluke Fasciola hepatica (Trematoda), the GLIR occurred in the longitudinal nerve cords and lateral nerves in the posterior half of the worm. GLIR was also detected in subtegumental fibres in F. hepatica. The presence of GABA was verified, using high-pressure liquid chromatography coupled with fluorescence detection. The concentration of GABA (mean ± S.D.) in M. expansa anterior region was 124·8 ± 15·3 picomole/mg wet weight, while in F. hepatica it was 16·8 ± 4·9 picomole/mg. Since several insecticides and anti-nematodal drugs are thought to interfere with GABA-receptors, the findings indicate that GABAergic neurotransmission may be a potential target for chemotherapy in flatworms too.
Structure and ultrastructure of muscle systems withinGrillotia erinaceusmetacestodes (Cestoda: Trypanorhyncha)
Authors: Ward S. M. , McKeer G. , Allen J. M. 
Published: June 2009

SUMMARYThree distinct muscle types have been identified within the metacestode ofGrillotia erinaceus. These consist of peripheral somatic myofibres plus two muscle systems directly involved in parasite attachment to the host, i.e. the tentacular bulb and its antagonistic retractor muscle. In common with other cestodes the somatic muscle consists of smooth-type fibres running longitudinally and obliquely to the main body axis. The retractor muscle consists of myofibres with centrally displaced nuclei. Upon contraction these latter fibres become spirally orientated causing the muscle to coil and lateral membranes to become elevated as spikes. Definitive nerve processes have not been identified within somatic or retractor muscle. Individual tentacular bulbs form the proximal terminus for a closed hydraulic system. Each bulb consists of overlapping, contrarotating myofibres which display obvious striations; the striations appear in alternate fibres to be in transverse and oblique planes. Adjacent myofibres are separated by approximately 0·5 μm, possess abundant mitochondria and have shallow t-tubules plus associated vesicles of sarcoplasmic reticulum at each Z line. Thick myofilaments are surrounded by 13, shared, thin myofilaments. Close neuronal control for the bulb muscle is suggested by the presence of obvious motor end-plates which contain both lucent and dense neurovesicles.
Echinococcus granulosus (Cestoda): uptake of L-amino acids by secondary hydatid cysts
Authors: Jeffs S. A. , Arme C. 
Published: June 2009

SUMMARYThe uptake of cycloleucine, L-proline, L-alanine and L-threonine by secondary hydatid cysts ofEchinococcus granulosus(U.K. horse strain 3–8 mm in diameter, derived from Balb/c mice infected 300–400 days previously) occurs by passive diffusion into the cyst wall (laminated layer plus germinal layer) and by mediated mechanisms into the fluid-filled interior. The maximal concentrations of these compounds are achieved after incubation for 2 hin vitroand approach thosein vivo.Ktand Vmaxvalues describing the uptake of these compounds are given. The flux rates for these compounds are extremely slow compared to those obtained with the protoscolex. A rationale for standardizing the experimental method for uptake studies with hydatid cysts is described.
Evidence for the absorption and synthesis of 5-hydroxytryptamine in perfused muscle and intestinal tissue and whole worms of adultAscaris suum
Authors: Chaudhuri J. , Martin R. E. , Donahue M. J. 
Published: June 2009

SUMMARYThe metabolites of 5-hydroxytryptamine (5-HT, serotonin) namely, L-tryptophan, 5-hydroxytryptophan, 5-hydroxyindole acetic acid and 5-hydroxytryptophol were measured in perfused tissue and whole worms from adult femaleAscaris suumusing reversed-phase liquid chromatography with electrochemical detection. The intracellular levels of each metabolite were quantitated in response to several physiological effectors but only Ltryptophan (TRP) caused dose-dependent changes in these metabolites. Serotonin itself could also be absorbed by perfusedA. suummuscle and intestinal tissue. When liveA. suumwere tied at the anterior and posterior regions to restrict TRP absorption by the intestine, TRP was absorbed through the cuticle and converted into 5-HT by the muscle tissue. In untied live parasites TRP absorption was observed in both muscle and intestinal tissue. Collectively, the data indicated that 5-HT may be either absorbed directly or synthesizedde novofrom absorbed TRP in the isolated tissue ofA. suum. The 5-HT, in the live adult femaleA. suum, can be synthesizedde novofrom TRP, or 5-HT can be absorbed from the environment both through the cuticle and by the intestine of living parasites. Data also indicated that there was preferential sequestering of 5-HT and the metabolites of 5-HT in the anterior tissues of the worms.
Glycans withN-acetyllactosamine type 2-like residues covering adultSchistosoma mansoni, and glycomimesis as a putative mechanism of immune evasion
Authors: Schmidt J. 
Published: June 2009

SUMMARYGlycans at the surface of adultSchistosoma mansoniwere investigated with gold-labelled lectins. The fragile complex of the glycans with the outer membranes could be preserved for electron microscopy by avoiding extensive pre-fixation with aldehydes and by introducing osmium-ferrocyanide as a membrane fixative. Male and female worms were entirely covered with glycans that intensely bound lectins fromErythrina cristagalliandDatura stramonium, suggesting that galactose(β1–4)N-acetylglucosamine residues occur in high numbers in the surface glycans. Similar staining was obtained with lectins fromTriticum vulgaris, Glycine maxandRicinus communisagglutinin I, which react withN-acetylglucosamine or terminal galactose residues and bind non-selectively with high affinity toN-acetyllactosamine. Fucose,N-acetylgalactose and sialic acid were not detected with lectins and sialidase treatment. The tegument contained an abundance of glycans with the same lectin reactivities as the surface-expressed molecules, indicating that the worms synthesize and replenish their surface glycans and do not merely adsorb host substances. Glycomimesis is discussed as a mechanism of immune evasion in view ofN-acetyllactosamine being a common and weakly immunogenic component in glycans of vertebrate hosts.S. mansonimight disguise themselves with the glycans against attack by immune effectors.
The action of serotonin and the nematode neuropeptide KSAYMRFamide on the pharyngeal muscle of the parasitic nematode,Ascaris suum
Authors: Brownlee D. J. A. , Holden-Dye L. , Fairweather I. , Walker R. J. 
Published: June 2009

SUMMARYThe pharyngeal component of the enteric nervous system of the parasitic nematode,Ascaris suumexhibits immunoreactivity for serotonin (5-hydroxytryptamine or 5-HT) and for FMRFamide-like peptides. This paper describes the application of anin vitropharmacological approach to investigate the functional role of 5-HT and FMRFamide-like peptides. The pharyngeal pumping behaviour ofAscaris suumwas monitored using a modified pressure transducer system which measures pharyngeal pressure changes and therefore pumping. The pharynx did not contract spontaneously; however, 5-HT (10-1000 μM) stimulated pumping at a frequency of 0·5 Hz. FMRFamide had no apparent effect on pharyngeal pumping. The native nematode FMRFamide-related peptide (FaRP), KSAYMRFamide inhibited the pumping elicited by 5-HT. The duration of inhibition was dose-dependent (0·1-1000 nM) with a threshold of 0·1 nM. In 4 preparations, the inhibition of the pharyngeal muscle was preceded by an initial excitation and increase in the amplitude of pharyngeal pressure changes. The pharynx is involved in various nematode processes, including feeding, regulation of hydrostatic pressure and excretion. The role of 5-HT and KSAYMRFamide in the pharyngeal function of nematodes is discussed.
Immune suppressive virus-like particles in a Drosophila parasitoid: significance of their intraspecific morphological variations
Authors: Dupas S. , Brehelin M. , Frey F. , Carton Y. 
Published: June 2009

SUMMARYThe Eucoilid parasitoid Leptopilina boulardi is able to suppress its host Drosophila melanogaster immune reaction. Some strains, however, are non-immune suppressive to that host. Virus-like particles (VLPs) responsible for the immune suppressive ability were investigated in different strains of L, boulardi with histochemical and ultrastructural techniques. Membrane-bound particles containing vesicles were observed in the reservoir of the long gland and also in the egg canal of the ovipositor. These particles are homologous with the immune suppressive VLPs already described in the reservoir of L. heterotoma. Similarities were also observed with the L2 particles described previously around the chorion of the parasitoid egg after infestation. A weak positive DNA specific histochemical reaction was observed inside the reservoir and at the ultrastructural level. Feulgen-derived techniques demonstrated that the reaction was localized inside the particles. The morphology of the particles as well as the immune suppressive ability varied between strains. Two morphotypes of VLPs are described; the ‘Is’ morphotype (always observed in immune suppressive or Is strains) and the ‘NIs’ morphotype (observed in the non-immune suppressive or NIs strain). The hybrids between Is and NIs strains produce a third type of particle, the ‘His’morphotype with half-immune suppressive ability and intermediate morphology. The origin of the particles' immune suppressive activity against D. melanogaster is discussed within the scope of host specificity.
The development of the body wall ofPolymorphus minutus(Acanthocephala) in its intermediate hostGammarus pulex
Authors: Butterworth Penelope E. 
Published: June 2009

The ultrastructure and development of the body wall ofPolymorphus minutusis described during the acanthella stages in the intermediate hostGammarus pulex.The cortex of the early acanthella is simple in structure, consisting of a syncytium containing giant nuclei, mitochondria, Golgi bodies, endoplasmic reticulum and a few lipid bodies. The cuticle is penetrated by pores which open into vesicles in a vesicular region.The cortex gives rise to the body wall, neck and lemnisci of the adult, and may be considered as divided initially into two and later three functionally different regions: an outer absorptive region, an inner storage region and a layer between which develops to provide firm, resistant skeletal protection.Absorption is facilitated by the increase in surface area due to the pores which penetrate the surface. This region is functional throughout development and the pores increase in number, possibly by division, as the animal grows. Beneath the pores a pore canal layer develops towards the end of the late acanthella stage.During development supporting fibres are deposited throughout the cortex. Beneath the vesicular layer a concentration of mitochondria, Golgi bodies and endoplasmic reticulum deposit the fibres of the felt layer. In the anterior meta-soma no felt layer is found, but the body spines originate from this region.The inner region of the cortex, or radial layer, contains the giant nuclei, which are arranged in the early acanthella in 5 rings of 4, 6, 5 or 6, 6 and 5 nuclei respectively. During development they produce dendritic process and finally fragment. They are considered here to be concerned with the formation of the felt layer and lemnisci rather than the ‘lacunar channels’. The inner cortical region becomes ensely packed with lipid bodies, and it is suggested that these may be responsible, owing to fixation artifact, for the so-called ‘lacunar channels’ previously described in these regions, the extensive cavities seen in some light microscope preparations being filled with a fluid lipid rather than an aqueous solution.The lemnisci are similar in appearance to the cortex except for regions of concentrated endoplasmic reticulum.The mitochondria in the cortex of the acanthella appear to be aerobic rather than anaerobic, as they possess many cristae and are larger than the mitochondria of the adults.My thanks are due to Dr D. W. T. Crompton for advice and encouragement, and to Dr D. H. Northcote and Dr F. B. P. Wooding for time on the Phillips Electron Microscope 100. This work was carried out during the tenure of an S.R.C. studentship.
Immunity in trypanosomiasis
Authors: Soltys M. A. 
Published: June 2009

Success in immunizing rabbits, rats and sheep with dead trypanosomes depends on the method of killing trypanosomes, the frequency of inoculations, and the strain used for immunization. Positive results were obtained when trypanosomes were killed by formalin or by freezing and thawing five times. Negative results were obtained when trypanosomes were killed by 56° C. for half an hour.Animals which received 10 doses of the mixture produced better results than those which received the same amount but only in 2 doses. An addition of Freund's adjuvant improved results, but 10 doses without an adjuvant were still better than 2 doses with an adjuvant. When trypanosomes were killed by 0·5% formalin, only an M variant of T. brucei, which was maintained by frequent passage in mice and was an antibody-sensitive variant, was able to produce in animals protective antibodies and resistance to a homologous ‘M’ variant, but not to an ‘R’ variant. On the other hand, if an ‘R’ variant of the same strain, which was passaged forty-eight times through rabbits and became resistant to antibodies, was killed by 0·5 % formalin and inoculated into animals, no antibodies and resistance could be demonstrated to a homologous ‘R’ variant and an ‘M’ variant.Although it is possible to produce immunity in animals with dead trypanosomes further studies, particularly in the field, are necessary to find its practical application.
Non-linear phenomena in host—parasite interactions
Authors: Anderson R. M. , May R. M. , Gupta S. 
Published: June 2009

SUMMARYThe paper examines non-linear dynamical phenomena in host—parasite interactions by reference to a series of different problems ranging from the impact on transmission of control measures based on vaccination and chemotherapy, to the effects of immunological responses targeted at different stages in a parasite's life-cycle. Throughout, simple mathematical models are employed to aid in interpretation. Analyses reveal that the influence of a defined control measure on the prevalence or intensity of infection, whether vaccination or drug treatment, is non-linearly related to the magnitude of control effort (as defined by the proportion of individuals vaccinated or treated with a drug). Consideration of the relative merits of gametocyte and sporozoite vaccines against malarial parasites suggests that very high levels of cohort immunization will be required to block transmission in endemic areas, with the former type of vaccine being more effective in reducing transmission for a defined level of coverage and the latter being better with respect to a reduction in morbidity. The inclusion of genetic elements in analyses of the transmission of helminth parasites reveals complex non-linear patterns of change in the abundance of different parasite genotypes under selection pressures imposed by either the host immunological defences or the application of chemotherapeutic agents. When resistance genes are present in parasite populations, the degree to which abundance can be suppressed by chemotherapy depends critically on the frequency and intensity of application, with intermediate values of the former being optimal. A more detailed consideration of the impact of immunological defences on parasite population growth within an individual host, by reference to the erythrocytic cycle of malaria, suggests that the effectiveness of a given immunological response is inversely related to the life-expectancy of the target stage in the parasite's developmental cycle.
Novel biochemical pathways in parasitic protozoa
Authors: Fairlamb A. H. 
Published: June 2009

SUMMARYThroughout evolution, enzymes and their metabolites have been highly conserved. Parasites are no exception to this and differ most markedly by the absence of metabolic pathways that are present in the mammalian host. In general, parasites are metabolically lazy and rely on the metabolism of the host both for a supply of prefabricated components such as purines, fatty acids, sterols and amino acids and for the removal of end-products. Nonetheless, parasites are metabolically highly sophisticated in that (1) they retain the genetic capacity to induce many pathways, when needed, and (2) they have developed complex mechanisms for their survival in the host. Certain unique features of the metabolism of trypanosomes, leishmania, malaria and anaerobic protozoa will be discussed. This will include (1) glycolysis and electron transport with reference to the unique organelles: the glycosome and the hydrogenosome, (2) purine salvage, pyrimidine biosynthesis and folic acid metabolism and (3) polyamine and thiol metabolism with special reference to the role of the unique metabolite of trypanosomes and leishmanias, trypanothione.
The ecology of immature phases of Trichostrongyle nematodes: II. The effect of climatic factors on the availability of the infective larvae of Trichostrongylus retortaeformis to the host
Authors: Crofton H. D. 
Published: June 2009

1. Eggs and larvae of Trichostrongylus retortaeformis were used.2. The rate of hatching of eggs was shown to be mainly related to temperature. From November to March, when maximum temperatures were below 50° F., there was no hatching. When maximum temperatures of 50–55° F. occurred eggs hatched on or before the fifteenth day, but never during the first 8 days. Eggs hatched in 8 days or less when maximum temperatures of 60–80° F. occurred.3. When the rate of evaporation in the air was high, eggs still hatched and reached the infective stage, the grass blades reducing the rate of loss of moisture from the faecal pellet. Laboratory experiments show that eggs may not develop to the infective stage if the faecal pellets are on a grassless portion of the pasture. This is most likely to occur when the rate of evaporation is high and the temperature low.4. Hatching may be delayed by cold conditions, but some eggs remain viable for long periods and they hatch when the temperature rises. Eggs passed by the host in the autumn can survive a cold winter and hatch in the spring, but eggs passed during the coldest period die.5. During periods when the maximum temperature never exceeded 55° F., little or no migration of larvae occurred. When temperatures rose above 55° F. the number of larvae migrating increased; but rise of temperature was associated with increase in the rate of evaporation. High rates of evaporation reduced the number of larvae migrating on the grass blades.6. Some infective larvae died soon after exposure on grass plots, but a small number survived long periods. In cold weather some larvae were still alive after 20 weeks. A high death-rate occurred in warm weather. A large proportion of the larvae died during periods in which the rate of evaporation was high; in one of these periods 95% of the larvae were dead at the end of 4 weeks' exposure.7. The number of larvae on grass blades of a pasture was shown to be dependent, at any time, upon the climate at that time, and upon past conditions which had influenced hatching and survival:
On the genusDinobothriumvan Beneden (Cestoda), with a description of two new species from sharks, and a note onMonorygmasp. from the electric ray
Authors: Sproston Nora G. 
Published: June 2009

A new species of the giant phyllobothriid genusDinobothrium(D. keilinin.sp.) is described from the blue shark (Carcharinus glaucus); it is compared withD. planumLinton, found for the first time from British waters, in the basking shark (Cetorhinus maximus), and the structure of both is discussed in relation to that of the genotype,D. septariavan Beneden. A fourth species,D. paciferumn.sp., also from the basking shark, is described, and though only a tenth the size of the other species, it shares most of their diagnostic scolex characters. It has eight true suckers above the four pendent bothria: inD. planumthere are four true suckers and four pseudo-suckers, while inD. keilinithere are only four true suckers, andD. septariais said to have four pseudo-suckers alone. The nomenclature of the older species is revised, and the genus redefined.Attention is directed to the adaptations in these large cestodes which facilitate interchange with the substratum: the development of lateral furrows through which the main excretory canals open to the exterior. There is also a ventral furrow, which in the nascent segments is an open cleft: this accommodates the growing uterus and permits a protracted gravid phase of the proglottidesin situ. The effect is of five longitudinal hinges, which allow of considerable lateral expansion of the thick-walled strobilus. The smallerD. paciferumlacks these modifications, and the cylindrical segments are apparently detached in the gravid state. An explanation is offered for the conflicting accounts of the lateral extent of the vitellaria in this genus: there is a lateral contraction of the ventral vitelline reticulum as the ovarian phase waxes. InD. paciferumthe vitellaria completely encircle the proglottis at the inception of the ovarian phase.Notes are given on the selachiàn hosts examined, their food and the other parasites present. The relationships ofDinobothriumto other phyllobothriid genera and toTetrabothriusare discussed.In one electric ray,Torpedo nobiliana, a single immature strobilus of another kind of phyllobothriid was found; it is probably a new species ofMonorygma, though it has slight resemblances toCalyptrobothrium—a genus characteristic of electric rays. The boat-shaped bothria are held at an angle from the scolex by contractile buttress-like wings, and at their proximal end there is a relatively large and complex sucker. Affinities with related genera are discussed and the nomenclature ofMonorygma angusta(Linton) is emended.