bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occurrence of fibronectin antigenic determinants onSchistosoma mansonilung schistosomula and adult worms
Authors: Ouaissi M. A. , Cornette J. , Capron A. 
Published: June 2009

SUMMARYFibronectin determinants were revealed in a soluble extract ofSchistosoma mansoniadult worms by standard immunodiffusion and immunoelectrophoresis techniques. The same target molecules were demonstrated on the parasite's surface using a binding assay with [125I] anti-fibronectin. The use of fluorescein- and peroxidase-conjugated antibodies confirmed the above observations and provided a fairly precise means for locating the cross-reacting antigen on the worm surface. Anin vitrocytotoxic assay using inactivated (56°C, 2 h) anti-fibronectin rabbit immune serum and guinea-pig serum as a source of complement was developed. In these conditions, anti-fibronectin exerted cytotoxic activity against lung schistosomula and adult worms but not skin schistosomula. The ultrastructural damage induced by anti-fibronectin in the presence of complement was studied using transmission electron microscopy. The results suggest a close association between fibronectin determinants andS. mansonimembrane.
Fecundity-reducing pheromone in Argas (Persicargas) arboreus (Ixodoidea: Argasidae)
Authors: Khalil Galila M. 
Published: June 2009

SUMMARYFed adult Argas (Persicargas) arboreus produce a fecundity-reducing pheromone which affects all or most females in crowded conditions. Unfed adults and unfed and fed nymphs do not produce this pheromone. The effect of this pheromone is probably additive, increasing with additional crowding of adults. Mechanical disturbance is excluded as the cause of fecundity reduction. Fed females separated by a perforated barrier from crowded adults also exhibit very low fecundity. Adult excretory materials used 31 days post-feeding do not contain the fecundity-reducing pheromone. Preliminary experiments suggest that this pheromone is spatially limited in action, does not affect gonadotropic hormone synthesis and/or release, and does not induce oviposition deterrence behaviour. This may be considered to be a primer pheromone, causing alteration in normal vitellogenin synthesis and/or uptake and deposition in oocytes. The source and chemical nature of this pheromone should be investigated.
The open-field behaviour of mice infected with Trichinella pseudospiralis
Authors: Rau M. E. 
Published: June 2009

SUMMARYThe behaviour of mice exposed to graded doses of Trichinella pseudospiralis larvae was monitored in an open-field situation. Ambulatory activity declined briefly during the acute phase of the infection (day 11) but regained pre-infection levels 1 week later. Animals receiving heavy doses of T. pseudospiralis exhibited a mild increase in the level of ambulatory activity during the chronic phase of the infection. The infections did not affect the level of exploratory activity. The effects of the T. pseudospiralis infections on the behaviour of the mouse host were much less pronounced than those induced by T. spiralis. It is suggested that these differences may be associated with the small size of T. pseudospiralis and the lack of capsule formation.
Schistosoma mansoni: a comparative study of schistosomula transformed mechanically and by skin penetration. Electrophysiological responses to a wide range of substances
Authors: Thompson D. P. , Pax R. A. , Bennett J. L. 
Published: June 2009

SUMMARYVolume conducted potentials were recorded from schistosomula ofSchistosoma mansonitransformed mechanically (MS) and by skin penetration (SS). The spontaneous electrical activity recorded consisted of bi and triphasic transients ranging from 20 to 200 μV in amplitude and 10 to 300 msec in duration. Low amplitude potentials occurred at a much greater frequency than large amplitude potentials, which appeared to correlate with peristaltic-like contractions of the schistosomulum's musculature. Electrical activity in the schistosomulum was highly sensitive to a number of agents believed to affect metabolic pathways, the neuromuscular system or the host/parasite interface of adult schistosomes. Among the most reactive substances were potassium antimony tartrate, eserine, poly-L-arginine and potassium cyanide. Over a wide range of experimental treatments, electrophysiological responses in schistosomula transformed from cercariae by mechanical decaudation and skin penetration were remarkably similar, supporting the notion that MS are suitable material forin vitroimmunochemical, biochemical and physiological study. Some treatments, however, were more or less effective in altering electrophysiological activity and motility in the schistosomulum than in adultS. mansoni. This suggests that significant physiological alterations may occur during development from skin stage to adult parasites concomitant with immunochemical and morphological changes already known to occur.
The structure of the intestine of Nematodirus battus and changes during the course of aninfection in lambs
Authors: Lee D. L. , Martin Jean 
Published: June 2009

SUMMARYThe structure of the intestine of adult Nematodirus battus is described. It is similar tothe intestine of some other trichostrongyles but with a few minor differences. Changes in the structure of the intestinal cells are described in N. battus taken from lambs during the later stages of an infection (days 20 to 32) with 60000 infected larvae. The mostnoticeable changes were a decrease in the amounts of glycogen and smooth endoplasmic reticulum, a reduction in the numbers of secretory-type granules and the appearance of vacuoles within the cells. Some of these vacuoles contained small crystals, and crystals, some of them large, were also found in the intestinal lumen. These changes, with the exception of the appearance of the crystals, are similar to changes described for Nippostrongylus brasiliensis affected by the immune response of the rat host, and it is concluded that the changes in N. battus could have been initiated by an immune response to this nematode in the lamb. Lambs given 2000 larvae of N. battus do not reject the nematodes in 32 days, and no changes were observed in the structure of these nematodes.
Formation of the cyst wall and related changes in the structure of the tegument ofBucephalus haimeanus(Lacaze-Duthiers, 1854) during its metamorphosis from the cercarial to the metacercarial stage
Authors: Higgins J. C. 
Published: June 2009

SUMMARYThe formation of the cyst wall surroundingBucephalus haimeanusand the related changes in the parasite tegument during its metamorphosis from the cercarial to the metacercarial stage have been investigated by means of experimental infections inGobiusculus flavescens. The initial fibrous cyst wall is formed from secretions produced by both the anterior gland cells and the tegument of the parasite. These secretions gradually become compacted against the surrounding hepatic cells until by the 20–30th day post-infection the 3-zoned inner layer, characteristic of the fully developed cyst wall, is formed. Hepatic cells immediately adjacent to this inner cyst wall layer are disrupted by the arrival of the metacercaria and form the middle vacuolated layer. As the metacercaria grows, the cyst increases in size causing still further hepatic cells to become flattened and incorporated into the cyst structure forming the outer nucleated layer. The structure of the cercarial tegument is described. Development of the metacercarial tegument is accomplished by the sequential movement of secretory vesicles from tegumental cell bodies into the outer cytoplasmic tegument. Vesicles of the types V. 1–5 are released from the outer cytoplasmic tegument, resulting in an almost complete breakdown of this layer prior to its replacement by the tegument of the fully developed metacercaria. The latter is characterized by the V. 6–9 type vesicles, dorso-ventrally flattened spines which terminate in 5–7 digits and by sensory cilia.
Light and gravity responses of the oncomiracidium ofEntobdella soleaeand their role in host location
Authors: Kearn G. C. 
Published: June 2009

SUMMARYThe behaviour of oncomiracidia of the monogenean skin parasiteEntobdella soleae, after hatching without chemical stimulation, has been studied in vertical, 4 cm high chambers illuminated from above. Most freshly hatched larvae are photo-positive and swim to the top of the vessel, where they remain actively swimming. Occasionally larvae become photo-negative and make a brief excursion to the bottom of the vessel. As the larvae grow older, these photo-negative excursions become more frequent and larvae spend progressively longer in the photo-negative phase of behaviour, but, even after many hours, photo-positive vertical excursions are still occurring. If this pattern of alternating photo-positive and photo-negative vertical movements occurs in the natural environment, these vertical movements, coupled with horizontal transport of larvae by water currents, would provide a search pattern for the host, the diurnally-inactive, bottom-living flatfishSolea solea. When eggs are stimulated to hatch in the chambers with urea, large numbers of larvae emerge within a few min, and it was observed that during the period of about 30 min after stimulation, many larvae are photo-negative. When eggs on the sea bottom are stimulated to hatch by mucus or urine from a nearby host, such behaviour would greatly enhance chances of contact with the fish. When eggs are stimulated to hatch by means of urea in the absence of light, there is evidence that the oncomiracidia are geo-negative. It has been shown that larvae are able to extricate themselves in total darkness from sediment containing buried eggs and that, in an experimental situation illuminated only by an infra-red beam, larvae readily attach themselves to the lower skin of soles within 2 min of hatching. There is evidence that, in aquaria, some invasion of the host takes place from below.
Variable expression of virulence in the rodent malaria parasitePlasmodium yoelii yoelii
Authors: Knowles G. , Walliker D. 
Published: June 2009

SUMMARYThe expression of the virulence character in the virulent line (YM) ofPlasmodium yoelii yoeliiwas investigated. The level of virulence was measured by counting the parasitaemia of the mature red blood cells. Several sub-clones were isolated from the virulent line YM and each was tested for its level of virulence. Out of 10 sub-clones 1 showed a marked decrease in virulence. However, transmission of this sub-clone through mosquitoes fully restored its virulence. A clone isolated from the progeny of a cross between mild and virulent parents had an intermediate level of virulence. A sub-clone isolated from this intermediate virulent line exhibited greatly reduced virulence. Mosquito transmission of this sub-clone also restored its virulence to a level comparable with the virulent line YM.
Transmission of Schistosoma mansoni from man to snail: laboratory studies on the influence of snail and miracidial densities on transmission success
Authors: Carter N. P. , Anderson R. M. , Wilson R. A. 
Published: June 2009

SUMMARYThe relationship between infection success, the density of Schistosoma mansoni miracidia and the density of the snail host Biomphalaria glabrata was examined experimentally. Within laboratory infection arenas, the distribution of miracidial infections/snail was approximately uniform and the net rate of snail infection was directly positive binomial to miracidial density. In contrast, however, the rate of infection declined exponentially as snail density increased. Mathematical models are developed to aid in the estimation of infection rates and experimental results are discussed in the context of the transmission dynamics of schistosomiasis.
The effect of mosquito transmission of antigenic variants ofPlasmodium chabaudi
Authors: McLean S. A. , Phillips R. S. , Pearson C. D. , Walliker D. 
Published: June 2009

SUMMARYPlasmodium chabaudiAS strain in mice is characterized by an acute primary parasitaemia, and one or more less acute recrudescences. Previous work has shown, using a passive protection assay, that the recrudescent parasites are usually antigenically different from parasites of the parent population with which the mice were first infected. In this study the effect of mosquito transmission on the antigenic expression of recrudescent populations ofP. chabaudiwas examined. In the first experiments the recrudescent population which was antigenically different from the parent population was uncloned. After transmission throughAnopheles stephensithe recrudescent population appeared to revert to an antigenic type similar to that of the parent population. In the second experiment clones from a recrudescent population were mosquito transmitted and again the parasites of the primary patent parasitaemia in the mice, bitten by the infected mosquitoes, had reverted to the parental type. It is suggested that antigenic variants ofP. chabaudiAS strain may revert to a basic type after mosquito transmission.
Metabolic changes associated with the migration of the schistosomulum ofSchistosoma mansoniin the mammal host
Authors: Ruth Lawson J. , Wilson R. A. 
Published: June 2009

SUMMARYA variety of measurements was made on small samples of schistosomula recovered from the skin, lungs and hepatic portal system of percutaneously infected mice, on the basis of which development could be divided into a migration and a growth phase. The density of schistosomula, estimated using a Ficoll gradient, was found not to vary significantly between Day 0 and Day 24 post-infection, having a mean value of 1·077. The reduced weight was measured by means of a Cartesian diver balance and used in conjunction with density to estimate the change in wet weight of schistosomula. Wet weight was found to decline slightly during the migration phase and to increase exponentially following arrival of schistosomula in the hepatic portal system. No change in nitrogen content was detected during migration but there was a rapid increase after arrival in the hepatic portal system. The rate of oxygen consumption, measured by Cartesian diver respirometer, declined significantly during migration and then increased exponentially after arrival of worms in the hepatic portal system. No change was detected in the lactic dehydrogenase activity of migrating worms but again, an exponential increase occurred after entry into the hepatic portal system. It was concluded that the migrating schistosomulum is in a semi-quiescent metabolic state, although it possesses the ability to take up nutrients and undergoes morphological changes. Growth is triggered by an unknown mechanism after arrival in the hepatic portal system. Examination of the various sets of data suggests that it is initiated between 10 and 11 days post-infection in the most advanced schistosomula.
Observations on the surface morphology of the ovarian balls ofMoniliformis(Acanthocephala)
Authors: Parshad V. R. , Crompton D. W. T. , Martin Jean 
Published: June 2009

SUMMARYThe surface morphology of fixed ovarian balls from femaleMoniliformis dubius, aged 12, 18, 26, 28, 42, 77, 105 and 118 days, has been examined by means of scanning electron microscopy. The appearance of the surface has been found to be variable between ovarian balls from worms of the same and different ages. Some parts of the surface are seen to possess micro-projections, cavities and ridges while other parts have the appearance of an irregular meshwork of fibres. Various protruding features have been observed to extend from the surfaces of the ovarian balls taken from the inseminated female worms. In most cases, the surfaces of the protruding features differ in appearance from the surrounding surfaces of the ovarian balls. Some of these features have been assumed to represent growing zygotes and developing eggs covered by the supporting syncytium of the ovarian ball. Single or several thread-like structures have been observed in association with the surfaces of ovarian balls taken from the inseminated female worms. At present, the thread-like structures are believed to be portions of spermatozoa. By means of light microscopy, preliminary observations have been made on what is considered to be the division process of ovarian balls taken from uninseminated and inseminated worms varying in age from 7 to 98 days.
The formation of surface membrane vesicles from schistosomula ofSchistosoma mansoni
Authors: Kusel J. R. , Gazzinelli G. , Colley D. G. , De Souza C. P. S. , Cordeiro M. N. 
Published: June 2009

SUMMARYIntact surface membrane vesicles were obtained and purified from the schistosomula ofSchistosoma mansoni. The method of preparation of the vesicles involved treating the schistosomula in a buffered high salt medium for 1 h at 4°C (Step 1), and then for 1 h at 25–37°C (Step 2). Vesicles were formed from mechanically- and skin-transformed schistosomula, and their size and number depended on the temperature of Step 2. The majority of the vesicles expressed surface membrane concanavalin A receptors and parasite antigens on their outermost surfaces. When incubated with sensitized peripheral blood mononuclear cell preparations from humans exposed to schistosomal preparations, the vesicles stimulated lymphocyte transformation as effectively as soluble egg and adult worm antigens. Although both preparations contained identical proteins, small vesicles were less effective than large vesicles in stimulating lymphocyte transformation. Hence, vesicles prepared under a variety of conditions might be used to study those factors which influence the presentation of membrane-bound surface antigens to the immune system of the host.
Helminths and the transmammary route of infection
Authors: Miller Grover C. 
Published: June 2009

SUMMARYThe transfer of infective larval stages of helminths via the mammary glands is probably more common than generally recognized. Recent investigations of both natural and experimental infections of various animals have shown that the transmammary transmission of some helminths is a major avenue of infection. Other studies indicate that there are at least 13 helminth parasites which may be transmitted as prenatal infections and at least 17 transmitted via the mammary glands. The majority of these are nematodes. However, in one case the tetrathyridia of the cestode Mesocestoides was observed. In this report the life-cycle and transmission of 2 species of diplostomatid trematodes in the genus Pharyngostomoides is described. The raccoon, Procyon lotor, is the only definitive host; a planorbid snail, Menetus dilatatus, and a branchiobdellid annelid, Cambarincola osceola, a commensal on crayfishes, are intermediate hosts. Records for a period of 11 years are now available for the maternal transmission and longevity of this trematode. During this time one infected female raccoon was maintained in the laboratory on a diet of commercial dog food, sweet potatoes and corn. She produced 25 offspring, most of which were infected with Pharyngostomoides, through the 6th litter. There was a declining number of worms in each litter, ranging from nearly 2000 in one of the 1st litter, to none in the 7th litter. After nearly 12 years she continues to pass a few trematode ova. Rather than assume she has retained the same adult worms for 12 years, it is reasonable to conclude that mesocercariae move through her body and eventually mature in the intestine. Because the mesocercariae have a predilection for the lactating mammary gland, it seems likely that a hormonal influence is present. The transmammary transmission of larvae is a viable alternative in the life-cycles of a number of helminths, and in some instances it is probably the major route of infection.
Functional antigens of Trichuris muris released during in vitro maintenance: their immunogenicity and partial purification
Authors: Jenkins S. N. , Wakelin D. 
Published: June 2009

SUMMARYThe immunogenicity of the secretory exo-antigen (EXA) originating in the stichosome of Trichuris muris has been investigated. High levels of immunity to challenge were produced using EXA (100 μg) by subcutaneous administration. Vaccination with a range of doses of EXA in Freunds' Incomplete Adjuvant (FIA) showed a dose response; 1 μg of EXA reduced the worm burden by 50% and doses of 10 μg or more reduced the worm burden by 80–90% at Day 9 post-infection. Worms recovered from vaccinated mice were significantly smaller than those from controls. A precipitin line identifiable with EXA was shown to immunize mice against T. muris challenge by vaccination. The protective antigen contained in EXA has been partially isolated using gel filtration, ion exchange filtration and isoelectric focusing and has been shown to be a protein of 30000 molecular weight having a pi of 6·8–7·3.
Use of species-specific DNA probes for detection and identification of trypanosome infection in tsetse flies
Authors: Kukla B. A. , Majiwa P. A. O. , Young J. R. , Moloo S. K. , ole-Moiyoi O. 
Published: June 2009

SUMMARYSpecies- and subspecies-specific trypanosome DNA hybridization probes have been employed in the detection and identification of trypanosome infections inGlossina morsitans centralis.Several ways of sample preparation including the use of tsetse organ suspensions, proboscides and dissected midguts, as well as tsetse abdominal content touch-blots were explored. The results of hybridization of radio-isotope-labelled species-specific DNA probes to tsetse samples indicated that it was possible to detect trypanosomes in the organs where parasite development is known to characteristically occur for each subgenus. Duplicate slot-blots of samples prepared from midguts of tsetse infected with 2 strains ofT. congolenseand from non-infected fly controls show that it is not only possible to detect infection in tsetse but also to identify the strain of parasite present in a sample after hybridization with the DNA probes specific for each strain. The results, obtained after hybridization of sequential abdominal touch-blots from the same fly with the DNA probe specific for one strain ofT. congolense,indicated that at least 8 positive signals can be observed after an overnight exposure. Because of their simplicity and potentially low cost, the techniques described here would be appealing for screening large numbers of tsetse samples from the field for the presence of any trypanosome residing in the guts or proboscis of the vector. In addition, the possibility of doing multiple touch-blots from the same fly gives the opportunity of detecting mixed trypanosome infections in the vector.
Regulation of mouse colony abundance byHeligmosomoides polygyrus
Authors: Scott Marilyn E. 
Published: June 2009

SUMMARYDespite the ubiquitous presence of parasites, parasitism has not been considered among the list of regulatory factors in animal populations until recently. A detailed long-term study on the impact of the direct life-cycle nematodeHeligmosomoides polygyruson a breeding population of laboratory mice provides a clear example of the ability of helminths to regulate host abundance. In the absence of the parasite, the mouse population equilibrated at a density of 320 mice/m2as a result of density-dependent effects on recruitment. When the parasite was added and transmission was maintained at high levels, infected mouse populations equilibrated at densities of < 18 mice/m2. Reduced rates of parasite transmission and elimination of the parasite from the system both resulted in an increase in mouse density. These results have implications for both ecology and parasitology as they demonstrate a potentially important but often ignored component of host populations that may well influence host abundance and community structure.