bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular characterization of twoSchistosoma mansoniproteins sharing common motifs with the vif protein of HIV-1
Authors: Khalife J. , Pierce R. J. , Godin C. , Capron A. 
Published: June 2009

SummaryWe have previously described a rat mAb directed against a peptide derived from the vif protein of HIV-1 that recognized twoSchistosoma mansoni(Sm) antigens with a major band at 65 kDa. Epitope mapping of this mAb using overlapping hexapeptides derived from the vif peptide revealed that the motif recognized was PLPSVT. The screening of a Sm cDNA library led to the identification of two clones, Sm70 and Sm65. The two deduced protein sequences did not share any common structural features apart from the epitope recognized by the mAb (see below), and did not show significant identity to sequences present in the data bases. However, the N terminus of the deduced sequence of the Sm70 protein exhibits a consensus sequence known to be an ATP/GTP binding site. Furthermore, the C terminus of the deduced Sm65 protein sequence was found to contain a conserved hexapeptide with a consensus sequence LPETGE reported to be an important motif of the surface proteins of gram-positive cocci. Both proteins exhibit a peptide sequence (PLRSVT for Sm70 and PVGSVT for Sm65) similar to the epitope recognized by the mAb anti-vif. Western blotting experiments showed that the mAb anti-vif reacted with both proteins. However, only Sm65 was recognized by sera from HIV-1- seropositive individuals, whereas both proteins were recognized by S.mansoni-infectedpatients.
The kinetics of repeated low-level infections of Nippostrongylus brasiliensis in the laboratory rat
Authors: Jenkins D. Conwil , Phillipson R. F. 
Published: June 2009

The kinetics of low-level repeated infections of Nippostrongylus brasiliensis in the laboratory rat were studied.The administration of five infective larvae each weekday to the rats produced an infection which was cumulative over 16 weeks and which did not produce an acute host immune response.The repeated administration of 50 larvae/weekday produced a primary immune response after 14 days. This caused partial worm expulsion and the suppression of egg output but the resistance of these rats to reinfection was not as pronounced as that seen in classical laboratory infections where heavier but less frequent larval exposures are used. The secondary worms that established in these rats did not elicit an acute host immune response even when the worm burden was as high as 756 worms.It is suggested that the kinetics of this type of infection more closely approximate those found under natural conditions than do those of a ‘classical’ laboratory infection.We wish to thank Misses G. Merchant, L. Cleaver and J. Cobb for able technical assistance, and Dr B. M. Ogilvie (National Institute for Medical Research, Mill Hill, London) for her helpful comments and discussions.
Aggregation in schistosomiasis: comparison of the relationships between prevalence and intensity in different endemic areas
Authors: Guyatt H. L. , Smith T. , Gryseels B. , Lengeler C. , Mshinda H. , Siziya S. , Salanave B. , Mohome N. , Makwala J. , Ngimbi K. P. , Tanner M. 
Published: June 2009

SUMMARYDistributions of the intensities of helminth infections within their host populations are invariably aggregated. In the case of the intestinal nematodes, the degrees of aggregation have been shown to be species specific, and constant for any given species despite geographical variation in study sites. This species-specific aggregation can be quantified and used as a tool in planning control interventions. One practical application is that the prevalence of infection can be used to predict the prevalence of heavy infection and thus the risks of morbidity. This paper investigates the patterns of aggregation in schistosome egg counts in different endemic areas in Africa (data sets were obtained from Burundi, Cameroon, Tanzania, Zambia and Zaire). The analysis demonstrates that the degree of parasite aggregation, for bothSchistosoma mansoniandS. haematobium, differs amongst the different study localities. This is probably due to area-specific differences in host exposure and immunity. This implies that for these schistosome species, it is not possible to predict egg count distributions or morbidity levels from prevalence data alone.
A dipeptidylpeptidase secreted byFasciola hepatica
Authors: Carmona C. , McGonigle S. , Dowd A. J. , Smith A. M. , Coughlan S. , McGowran E. , Dalton J. P. 
Published: June 2009

SUMMARYA dipeptidylpeptidase (DPP) was isolated fromFasciola hepaticaby gel-filtration and ion-exchange chromatography. The exoproteinase is secreted by newly excysted juveniles, immature and mature flukes. The liver fluke DPP is a serine proteinase of molecular weight > 200 kDa and differs from previously characterized mammalian DPPs in its substrate preference and susceptibility to inactivation by inhibitors. The parasite DPP may function in the latter stages of the proteolytic digestion of host macromolecules. In this manner, the enzyme may be important in providing the parasite with dipeptides that could be absorbed through the intestine as nutrient.
Evolution and overview of classical transmitter molecules and their receptors
Authors: Walker R. J. , Brooks H. L. , Holden-Dye L. 
Published: June 2009

SUMMARYAll the classical transmitter ligand molecules evolved at least 1000 million years ago. With the possible exception of the Porifera and coelenterates (Cnidaria), they occur in all the remaining phyla. All transmitters have evolved the ability to activate a range of ion channels, resulting in excitation, inhibition and biphasic or multiphasic responses. All transmitters can be synthesised in all three basic types of neurones, i.e. sensory, interneurone and motoneurone. However their relative importance as sensory, interneurone or motor transmitters varies widely between the phyla. It is likely that all neurons contain more than one type of releasable molecule, often a combination of a classical transmitter and a neuroactive peptide. Second messengers, i.e. G proteins and phospholipase C systems, appeared early in evolution and occur in all phyla that have been investigated. Although the evidence is incomplete, it is likely that all the classical transmitter receptor subtypes identified in mammals, also occur throughout the phyla. The invertebrate receptors so far cloned show some interesting homologies both between those from different invertebrate phyla and with mammalian receptors. This indicates that many of the basic receptor subtypes, including benzodiazepine subunits, evolved at an early period, probably at least 800 million years ago. Overall, the evidence stresses the similarity between the major phyla rather than their differences, supporting a common origin from primitive helminth stock.
Functional morphology of the platyhelminth nervous system
Authors: Halton D. W. , Gustafsson M. K. S. 
Published: June 2009

SUMMARYAs the most primitive metazoan phylum, the Platyhelminthes occupies a unique position in nervous system evolution. Centrally, their nervous system consists of an archaic brain from which emanate one or more pairs of longitudinal nerve cords connected by commissures; peripherally, a diverse arrangement of nerve plexuses of varying complexity innervate the subsurface epithelial and muscle layers, and in the parasitic taxa they are most prominent in the musculature of the attachment organs and egg-forming apparatus. There is a range of neuronal-cell types, the majority being multi- and bipolar. The flatworm neuron is highly secretory and contains a heterogeneity of vesicular inclusions, dominated by densecored vesicles, whose contents may be released synaptically or by paracrine secretion for presumed delivery to target cells via the extracellular matrix. A wide range of sense organ types is present in flatworms, irrespective of life-styles. The repertoire of neuronal substances identified cytochemically includes all of the major candidate transmitters known in vertebrates. Two groups of native flatworm neuropeptides have been sequenced, neuropeptide F and FMRFamide-related peptides (FaRPs), and immunoreactivities for these have been localised in dense-cored neuronal vesicles in representatives of all major fiatworm groups. There is evidence of co-localisation of peptidergic and cholinergic elements; serotoninergic components generally occupy a separate set of neurons. The actions of neuronal substances in flatworms are largely undetermined, but FaRPs and 5-HT are known to be myoactive in all of the major groups, and there is immuno-cytochemical evidence that they have a role in the mechanism of egg assembly.
Metabolism and inactivation of neurotransmitters in nematodes
Authors: Isaac R. E. , Macgregor D. , Coates D. 
Published: June 2009

SUMMARYThe nematode nervous system employs many of the same neurotransmitters as are found in higher animals. The inactivation of neurotransmitters is absolutely essential for the correct functioning of the nervous system, In this article we discuss the various mechanisms used generally in animal nervous systems for synaptic inactivation of neurotransmitters and review the evidence for similar mechanisms operating in parasitic and free-living nematodes. The sequencing of the entireCaenorhabditis elegansgenome means that the sequence of nematode genes can be accessed from theC. elegansdatabase (ACeDB) and this wealth of information together with the increasing knowledge of the genetics of this free-living nematode will have great impact on all aspects of nematode neurobiology. The review will provide an insight into how this information may be exploited to identify and characterize target proteins for the development of novel anti-nematode drugs.
Cell relationships in Hymenolepis diminuta
Authors: Threadgold L. T. , Read C. P. 
Published: June 2009

SUMMARYThe intimate cell relationships of Hymenolepis diminuta are described and occur between cells of the parenchyma, excretory system, muscle and tegument. The cell relationships are of three types: (a) a tight junction or zonula occludens; (b) a desmosome-like structure without tonofibrils or intercellular dense line; (c) a junctional complex with modified unit membranes and an intercellular region of dense granules and fibres.This research was begun while one of us (L.T.T.) was a Visiting Lecturer in the Biology Department, Rice University, and completed in the Zoology Department, Queen's University, Belfast. We should like to thank Dr C. W. Philpott for allowing us the full use of the facilities of his electron-microscope unit and Mr W. Ferguson for photographic assistance.
Characterization of cell types in the parenchyma ofSchistosoma mansoni
Authors: Reissig Magdalena 
Published: June 2009

SUMMARYA study has been made of the parenchyma of adult maleSchistosoma mansoniby electron microscopy. Four different cell types have been characterized: one corresponding to cell bodies of the integument, two to muscle cells and another one to nerve cells with a possible neurosecretory function. The cytoplasm of the integument cell bodies is characterized by rod-shaped and round membrane-bound cytoplasmic bodies with a dense core, measuring 1200 to 2000 Å, similar to those found in the integument. One type of muscle cell has a large, clear nucleus, characteristic cytoplasmic vacuoles measuring up to 1 μm with a finely granular content and numerous free ribosomes. The other type of muscle cell is much smaller, with clumped nuclear chromatin and scanty perinuclear cytoplasm. Both types of cells give rise to muscle fibres which are morphologically distinct from the perinuclear cytoplasm. The nerve cells contain electron-dense, membrane-bound vesicles-ranging in size from 1000 to 3000 Å, similar to those found in nerve axons.Appreciable extracellular matrix has only been found under the integument and surrounding the processes of the integument cell bodies. This observation and the fact that silver methenamine after periodic oxidation stains intensely both the extracellular substance and the rod-shaped and round cytoplasmic bodies of the integument cells, suggests that these integument cells may be involve the production of extracellular matrix.This investigation was supported by grant AI 07806 from the U.S.P.H.S.The technical assistance of Mrs Lucille Jeffries and the photographic assistance of Mr William Douglas are acknowledged. This investigation was supported by the United States–Japan Cooperative Medical Science Program administered by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, Department of Health, Education and Welfare.
Studies on ascaridoid nematodes in pythons: the life history and development of Polydelphis anoura in Australian pythons
Authors: Sprent J. F. A. 
Published: June 2009

SUMMARYP. anoura was found in 55 % of pythons (M. spilotes variegatus) in Brisbane. Eggs contained first stage larvae after 8 days development; the first moult was completed by 10 days; the eggs were infective after 14 days. After ingestion by tadpoles, the larvae hatched from the eggs and migrated into the tissues but did not show any growth. In mice and rats the larvae migrated mainly to the liver, lungs and intestinal wall, where growth occurred to a length of 5–6 mm by 6 months after infection. The second moult was not observed, but the larvae were infective to pythons after 39–42 days development. From their structure it was assumed that after this time the larvae in mouse tissues were third-stage larvae.Various species of Australian python, Morelia spilotes, Liasis amethistinus, L. fuscus and L. childreni, were experimentally infected with larvae of Polydelphis anoura by feeding nodules from the wall of the small intestine of experimentally infected mice and rats. The third moult occurred in the stomach within 14 days, moulting larvae at this stage measured between 3.5 and 7.0 mm long. Fourth-stage larvae occurred in all python species, the smallest being 4 mm. Growth and development of the fourth stage occurred at first in the oesophagus and stomach. Up to 2 months after infection, larvae had not grown more than 12 mm, yet they were clearly differentiated into males and females. In mouse-infected M. spilotes growth to 20 mm was reached by 154 days, but it was not until 183 days that adults were observed.Comparison with adult specimens from P. reticulatus from Malaya confirmed the previous observation that Australian male specimens have relatively shorter spicules than male specimens from other geographical regions. Growth, development and location of larvae in mice, experimentally infected with eggs from Australian and Malayan specimens, appeared to be the same.
An unusual form of fertilization in the malaria parasite of the Himalayan flying squirrel
Authors: Dasgupta B. , Chatterjee Amal 
Published: June 2009

SUMMARYFertilization phenomena has been observed in the malaria parasite of the Himalayan Flying Squirrel with blood showing heavy infection. The blood was obtained on the slide, put in the moist chamber, dried and stained. Two types of microgametes could be distinguished. One of these two types were found in various stages of the process of fertilization. More than one microgamete were often found to take part in fertilizing a single macrogamete. This is the first recorded case of polyspermy in malaria parasites.Thanks are due to Mr Nandalal Pau for his help in preparing the Plate incorporated in this paper.This investigation received financial support from the World Health Organization.
Physiological and pharmacological properties of muscle cells isolated from the flatwormBdelloura candida(Tricladia)
Authors: Blair K. L. , Anderson P. A. V. 
Published: June 2009

SummaryA protocol for dissociating single muscle fibres from intact flatworms was developed. Muscle fragments of various sizes were obtained, many with their cell bodies, or myocytons, intact. Many of the fibres were spontaneously contractile, and they and others contracted in response to applications of transmitter candidates, activators of protein kinase C and the anthelmintic praziquantel. The responses were all similar to those evoked in strips of tissue. Voltage clamp recordings from the isolated muscle fibres revealed that they possess an inward Ca2+current and 3 separate K+currents. These results indicate that muscle fibres inBdellourabear receptors for neurotransmitters and that preparations of dispersed muscle fibres can be used for studying the basic physiological and pharmacological properties of platyhelminth muscle.
The development and validation of an age-structured model for the evaluation of disease control strategies for intestinal helminths
Authors: Chan M. S. , Guyatt H. L. , Bundy D. A. P. , Medley G. F. 
Published: June 2009

SummaryEpidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted treatment programmes. The model was verified using field data from control programmes forAscaris lumbricoidesandTrichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes.
Complete developmental cycle ofLeishmania mexicanain axenic culture
Authors: Bates P. A. 
Published: June 2009

SUMMARYA complete developmental sequence ofLeishmania mexicanahas been produced in axenic culture for the first time. This was achieved by manipulation of media, pH and temperature conditions over a period of 16 days. All experiments were initiated with lesion amastigotes that were transformed to multiplicative promastigotes by culture in HOMEM, 10% foetal calf serum, pH 7·5, at 25 °C. Metacyclogenesis was induced by subpassage in Schneider'sDrosophila medium, 20% foetal calf serum, pH 5·5, and the resulting forms transformed to axenically growing amastigotes by subpassage in the same medium and raising the temperature to 32 °C. Parasites from each day were characterized with respect to their general morphology using light microscopy of Giemsa-stained smears, and biochemically by analysis of total protein content, proteinases, nucleases and secretory acid phosphatase. The results demonstrated that the three main stages identified - amastigotes, multiplicative promastigotes and metacyclic promastigotes - each exhibited the expected suite of biochemical properties. Further, the changes in morphology observed as the developmental sequence proceeded from stage to stage were accompanied by appropriate changes in biochemical properties. These results provide both useful biochemical markers and a culture system in which to examine the regulation of differentiation and transformation during theLeishmanialife-cycle.
Genomic and phenotypic diversity of TunisianTheileria annulataisolates
Authors: Miled L. Ben , Dellagi K. , Bernardi G. , Melrose T. R. , Darghouth M. , Bouattour A. , Kinnaird J. , Shiels B. , Tait A. , Brown C. G. D. 
Published: June 2009

SUMMARYThis study describes polymorphism inTheileria annulata, an intracellular protozoan parasite of bovine leucocytes and red blood cells. Fifty-three different stocks ofT. annulata, isolated from 17 sites (districts) in Tunisia, have been characterized by anti-parasite monoclonal antibody (MAb) reactivity, glucose phosphate isomerase (GPI) isoenzyme electrophoresis, and Southern blotting with two genomic DNA probes. There appears to be considerable diversity amongstT. annulatastocks from Tunisia, no two isolates being identical, even those from animals on the same farm. Two distinct antigenic populations were detected by MAb 7E7. They were defined by negative and positive cells in the indirect fluorescent antibody test. The percentage of positive cells in different isolates ranged between 0 and 100%. The population variation seen by GPI analysis and DNA probes was greater; 7 different GPI phenotypes were identified amongst the stocks studied, while DNA probesT. annulataTunis (TaT) 17 and 21 detected up to 5 different variants. The majority of isolates were shown to contain more than one parasite population, the number of variants per isolate ranging from 1 to 4. No correlation between particular parasite phenotypes or genotypes and their geographical site of isolation was observed. Selection of parasite populationsin vivoandin vitrois also discussed.
Genetic relatedness as a determinant of predisposition to Ascaris lumbricoides and Trichuris trichiura infection
Authors: Chan L. , Bundy D. A. P. , Kan S. P. 
Published: June 2009

SUMMARYThe present study examines the role of host genetics in predisposition to Ascaris lumbricoides and Trichuris trichiura infection, by comparing the associations between age-standardized infection intensities of parents and their children (genetically related), with age-standardized infection intensities of parents alone (not related), within families previously demonstrated to exhibit familial predisposition. The lack of a consistent trend in infection intensity associations within families, in particular the lack of a stronger association between parents and their children than between unrelated parents, suggests that host genetic factors are not a major determinant of infection status. If there is a genetic basis for predisposition, then the data suggest that the effects of this genetic basis are overwhelmed by other, environmental or behavioural features of the family household.
Characterization of identifiable neurones in the head ganglia of the parasitic nematode Ascaris suum: a comparison with central neurones of Caenorhabditis elegans
Authors: Holden-Dye L. , Walker R. J. 
Published: June 2009

SUMMARYIntracellular recordings have been made from neurones in the head ganglia of Ascaris. The neurones had low resting membrane potentials of –21±9 mV (n = 78) and a relatively high input resistance (e.g. 25 MΩ for a 100 μm cell). In all cases the intracellular location of the recording electrode was verified by injection of the fluorescent marker, 5, 6-carboxyfluorescein (CBXF). To ascertain whether or not the low membrane potential was due to impalement damage, the same neurone was recorded from using two microelectrodes. The membrane potential following the first impalement by a 20 MΩ 3 M KCl electrode was –38 mV and following the second impalement by a 80 MΩ CBXF (for subsequent intracellular labelling) electrode was decreased to –34 mV. Input resistance of these cells was estimated using both single and two electrode intracellular recording techniques and in both cases yielded a relatively high value for the size of cell (e.g. 25 MΩ for a 100 μm cell). Neurones labelled by intracellular injection of the fluorescent marker 5, 6-carboxy-fluorescein were morphologically simple and lacked extensive arborizations. The dorsal ganglion is a discrete structure consisting of only 3 neurones. Here we compare the morphological properties of these neurones to those described in the dorsal ganglion of Caenorhabditis elegans. The whole mount preparation of Ascaris ganglia thus provides a useful model to study the functional properties of neurones in nematode central nervous system and presents the possibility to assess central sites of action for anthelmintics.