bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host specificity, host location and dispersal: experimental conclusions from freshwater mites (Unionicolaspp.) parasitizing unionid mussels
Authors: Barbara Downes J. 
Published: June 2009

SUMMARYParasites with low host specificity are predicted to search for hosts in ways less specific than highly host-specific species. They may also be better dispersers. Unionicolan mites that parasitize mussels are positively phototactic, with some species becoming negatively phototactic when host substances are present. This response has been interpreted as an aid to host location and occurs in species where adult mites have a relatively permanent association with hosts. Three species ofUnionicola(Unionicolidae: Acari) that differ in host specificity co-occur in freshwater mussels (Unionidae) in St Mark's River in north Florida.
Effect of Praziquantel treatment on lung-stage larvae ofSchistosoma mansoni in vivo
Authors: Flisser Ana , McLaren Diane J. 
Published: June 2009

SUMMARYMice infected heavily withSchistosoma mansonicercariae were treated 6 days later with Praziquantel and the parasites studied 1 h post-treatment. Immunofluorescence experiments showed that parasite surface antigens became available for labelling in larvae harvested from Praziquantel-treated mice, but not from untreated mice. Red blood cell antigens acquired from the host were localized on all lung worms studied. The distribution of each set of antigens, as revealed by fluorescence-labelling was, however, quite different. The lungs of heavily infected, drug-treated mice, exhibited severe haemorrhages which occurred in a dose-dependent manner. Fewer haemorrhages were found when heavily infected mice were treated simultaneously with Praziquantel and Aprotinin, a proteinase inhibitor. These results indicate that Praziquantel treatmentin vivoinduces the exposure of parasite antigens on lung-stage worms and may cause the release of parasite-derived enzymes which induce haemorrhages in the lung tissue of the host.
Immunocytochemical demonstration of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica (Trematoda, Digenea)
Authors: Magee R. M. , Fairweather I. , Johnston C. F. , Halton D. W. , Shaw C. 
Published: June 2009

SUMMARYThe localization and distribution of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica at different stages in the development of the adult fluke have been determined by an indirect immunofluorescence technique, using antisera to 19 vertebrate peptides and the invertebrate neuropeptide, FMRFamide. Positive immunoreactivity was obtained with antisera to pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), substance P (SP) and FMRFamide. Cell bodies and nerve fibres immunoreactive to the 4 peptides are present in the anterior ganglia and the 3 pairs of longitudinal nerve cords and their commissures in the central nervous system. In the peripheral nervous system, immunoreactivity occurs in the nerve plexuses supplying the subtegumental musculature, the oral and ventral suckers, and the muscular lining of the male and female reproductive ducts, including the ootype, uterus, cirrus pouch and gonopore. Cells displaying immunoreactivity to PYY and FMRFamide lie amongst the Mehlis' gland cells that surround the ootype. Processes from these cells extend into the wall of the ootype. One group of PP-immunoreactive cells occurs at the junction of the vitelline and ovovitelline ducts, whilst another group is situated at the entrance to the uterus from the ootype. The results are discussed in relation to the possible roles of the peptides in the neurophysiology and egg production of the fluke.
Translation in a reticulocyte cell-free system of RNA isolated from blood and culture forms of Trypanosoma brucei
Authors: Eggitt M. J. , Tappenden L. , Brown K. N. 
Published: June 2009

RNA with messenger activity has been extracted from both blood and culture (insect mid–gut) forms of Trypanosoma brucei and translated in a reticulocyte cell–free system. The products of this cell–free system have been compared, and many common polypeptides demonstrated. A major polypeptide of 58000–65000 molecular weight was made when both blood and culture from RNA was added to the cell–free system.Antiserum raised against purified variant antigen from a cloned variant (MIAG 099) was used to detect specific products of this system. A major polypeptide of approximately 58000–65000 molecular weight was precipitated when the homologous trypanosome (MIAG 099) blood form RNA was used in the cell–free system. No such polypeptide was precipitated when RNA from a heterologous strain culture or blood form was used in the system. Competition experiments, in which excess purified variant antigen was added after incubation but before addition of specific antiserum, confirmed that the polypeptide of 58000–65000 molecular weight is the variant antigen.Poly(A)–containing RNA from trypanosomes was shown to contain the mRNA for the variant antigen.
Human malaria infectiousness measured by age-specific sporozoite rates in Anopheles gambiae in Tanzania
Authors: Lines J. D. , Wilkes T. J. , Lyimo E. O. 
Published: June 2009

SUMMARYIn an area of holoendemic malaria in Northern Tanzania, Anopheles gambiae s.l. females were age-graded by Polovodova's method and dissected for sporozoites. Age-specific sporozoite rates implied that mosquitoes acquired new infections at all ages. The extrinsic period lasted just over 3 gonotrophic cycles (9–11 days). Very high sporozoite rates in the oldest females implied the absence or rarity of genetic refractoriness to infection. A method is described for estimating the proportion of bloodmeals which result in mosquito infection. This method makes relatively few assumptions about mosquito behaviour, and could be useful for evaluating transmission-blocking interventions. Overall, it is estimated that about 21% of meals are infectious. This is much higher than previous estimates derived either from experimental mosquito feeding studies or from similar age-grading data collected from the same area in 1962. Various alternative explanations are considered, and it is concluded that there has been a 2.5-fold increase in human infectiousness in the last 25 years. This is partly attributable to suppression of human infectiousness by widespread chloroquine usage during the 1960s, followed by removal of this effect by drug resistance. It is argued that chloroquine would be expected to select for increased infectivity in the parasite, and this may also have contributed to the observed increase.
In vitrocultivation ofTrypanosoma congolensebloodstream forms in the absence of feeder cell layers
Authors: Hirumi H. , Hirumi K. 
Published: June 2009

SUMMARYBloodstream forms ofTrypanosoma congolense(2 clones: ILNat3·1 and IL3000, and 4 stocks: IL2079, IL2466, IL3266 and CP-81) were continuously cultivatedin vitroat 34–36 °C in the absence of feeder cell layers, using HMI-93 medium which was modified from Iscove's modified Dulbecco's MEM (Flow Laboratories, Irvine, Scotland). The modification was done by supplementing the medium with 0·05 mM bathocuproine sulphonate, 1·5 mM L-cysteine, 0·5 mM hypoxanthine, 0·12 mM 2-mercaptoethanol, 1 mM sodium pyruvate, 0·16 mM thymidine, 20% (v/v) heat-inactivated young goat serum and 5% (v/v) Serum Plus™ (Hazleton Biologics, Lenaxa, KS, USA). Trypanosomes obtained from two different sources were used to initiate primary cultures: (1) metacyclic forms which were producedin vitroat 27 °C, and (2) bloodstream forms obtained from Balb/c mice which had been infected with the bloodstream forms transformedin vitrofrom the metacyclic forms. Metacyclic forms placed in 25 cm2T-type (T-25) flasks rapidly attached to the bottom of the flasks and transformed to bloodstream forms during the initial 24 h and continued to proliferate. The bloodstream forms isolated from the infected mouse blood by means of diethylaminoethyl cellulose (DE52) column chromatography also continued to proliferate in the flasks. Cultures were maintained by replacing the medium every 24 h. Every 4–5 days, the attached bloodstream forms were resuspended in fresh medium by gentle pipetting and then were subcultured. The method was further simplified by initiating primary cultures directly with 10 μl of the tail blood of infected mice in 24-well culture plates and then by subcultivating either in wells or in T-25 flasks. The shortest population doubling time, 9 h, was achieved by seeding subcultures with 106bloodstream forms/ml. The bloodstream forms propagated in this system were morphologically similar to those seen in infected mouse blood, they were covered with a surface coat as examined by electron microscopy and they were infective to mice.
The epidemiology of Schistosoma spindale Montgomery, 1906 in cattle in Sri Lanka
Authors: De Bont J. , Vercruysse J. , Van Aken D. , Southgate V. R. , Rollinson D. , Moncrieff C. 
Published: June 2009

SUMMARYDuring 1988 and 1989, the mesenteric veins of 901 cattle were examined for the presence of schistosomes at the Kandy slaughterhouse (Sri Lanka). The overall prevalence of infection was 31·2%. Animals younger than 2 years were less infected (21·3%) than those older than 5 years (47·9%). Based on the number of paired worms counted, three intensities of infection were recognized: low (1–20 pairs), moderate (21–100 pairs) and heavy (> 100 pairs). Intensities increased with the age of the animals but remained low (average 10 worm pairs). The worm burden increased by approximately 20% for each step in age group. The number of miracidia/100 g faeces was measured in 85 animals of all age groups and intensities of infection; 77% of the samples contained less than 100 miracidia. Miracidia counts decreased with age; moderately and heavily infected animals in each age group had the highest and the lowest counts, respectively. This may be due to a host immune response. The results raise questions on the sensitivity of faecal egg counts as a diagnostic method for visceral schistosomiasis in cattle.
Membrane structure and function of malaria parasites and the infected erythrocyte
Authors: Sherman Irwin W. 
Published: June 2009

SUMMARYAccording to the World Health Organization the global estimate of malaria is over 200 million infections, the majority of which are caused by the most life-threatening species,Plasmodium falciparum(Report of the Steering Committees of the Scientific Working Groups on Malaria, World Health Organization, June 1983). The causative agent of the disease, the malarial parasite, requires two hosts: a blood-sucking mosquito and a blood-containing vertebrate. Commonly, infection of the vertebrate begins when an infected mosquito bites a suitable vertebrate and injects minute sporozoites into the bloodstream. Within 30 mm the introduced sporozoites leave the bloodstream and enter parenchymal cells of the liver (mammals) or endothelial cells (birds). In these sites the parasite undergoes asexual multiplication (= exo-erythrocytic schizogony) producing daughter progeny called merozoites. The exo-erythrocytic merozoites are released from the tissues into the circulation where they invade red blood cells. Within an erythrocyte the merozoite undergoes asexual multiplication (= erythrocytic schizogony) producing a substantial number of merozoites. The erythrocyte lyses, merozoites are released, and invasion of another erythrocyte may then take place. The synchronous rupture of the red cell and merozoite release is marked by the periodic fever–chill cycles so characteristic of the malarial infection. Some merozoites continue to reinvade other erythrocytes and multiply by asexual means, whereas others enter erythrocytes and differentiate into sexual stages, male or female gametocytes. When a suitable mosquito feeds on an infected vertebrate gametocytes are ingested and the sexual cycle of development is initiated. In the mosquito stomach the gametocytes transform into gametes, fertilization takes place, the resultant worm-like zygote penetrates the cells of the mosquito gut and comes to lie on the outer surface of the stomach. Here each zygote forms a cyst-like body, the oocyst, within which thousands of sporozoites are produced by asexual multiplication. When the swollen oocysts burst, sporozoites are freed and these make their way to the salivary gland. At the next blood feeding the mosquito injects the infective sporozoites and the life-cycle is completed.
Acquired immunity toSchistosoma mansoniin the rat: measurement of immunity by the lung recovery technique
Authors: Perez Hilda , Clegg J. A. , Smithers S. R. 
Published: June 2009

Acquired immunity toSchistosoma mansoniin the rat can be assayed by the recovery of a proportion of the schistosomula of a challenge infection from the lungs 5 days after the challenge has been given. The recoveries from immune rats, which are significantly less than those from control animals, demonstrate that a proportion of a challenge infection is killed in the lungs or at an earlier point in the pathway of migration.Immunity in the Sprague–Dawley rat can first be shown by the lung recovery technique 3 weeks after an immunizing exposure of 500 cercariae. Immunity reaches a peak between weeks 6 and 7 but then declines to zero by week 12. The PVG inbred Hooded rat shows a similar but delayed development and decline of immunity. When the lung recovery technique shows immunity to be declining, hepatic perfusion demonstrates that immunity to reinfection is partially retained, indicating that at this stage the challenge is killed after the first 5 days.Re-exposure of rats in which immunity has declined induces an anamnestic lung recovery response. There appears to be a relationship between spontaneous cure and the decline of immunity. A factor in the serum of infected rats which kills young schistosomula in culture develops in parallel with immunity, but high titres of this factor are maintained during the decline of immunity.
Functional bursting by the dracunculoid nematodePhilonema oncorhynchi
Authors: Lewis J. W. , Jones D. R. , Adams J. R. 
Published: June 2009

Using biomedical techniques experimental determinations of the hydrostatic pressure in the pseudocoel of adult femalePhilonema oncorhynchiindicated that the rate of increase in pressure (dP/dT) and absolute pressure values (cm/H2O) shown by bursting worms in distilled water are correlated with the diameter of the nematode. At bursting pressures, wall tension in a wide size range of worms was virtually identical, indicating that the bursting process is independent of muscular contraction. That the generation of the hydrostatic pressure was an osmotic phenomenon was confirmed by measuringdP/dTin prelarvigerous and larvigerous female worms subjected to different concentrations of sodium chloride, ranging from 89 to 800 m-osmol/kg, and also to a variety of solutions of similar osmolarity (155–175 m-osmol/kg),e.g.magnesium sulphate, urea, potassium chloride, sodium chloride and sucrose. The overall rate of uptake was faster in the larger worms but, per unit surface area, small worms had an uptake rate three times that of the large individuals.The prediction that the body wall of femaleP. oncorhynchiis permeable to ions such as Na+ was confirmed using radiolabelled22Na and by bringing about changes in the osmolarity of worms subjected, for 5 min periods, to hyperosmotic solutions of sodium chloride and sucrose. The survival ofP. oncorhynchiin the body cavity of sockeye salmon,Oncorhynchus nerka, is dependent upon the permeable nature of the body wall ofP. oncorhynchiallowing the worm to function as an ‘osmometer', because as the anadromousO. nerkaenters fresh water, the osmolarity of its blood plasma is known to decrease by about 15%. At the time of spawning in Cultus Lake, British Columbia, the body fluids of both femaleP. oncorhynchiandO. nerkaare isosmotic, indicating that the worms are able to equilibrate to the above changes and at the same time preventing premature bursting in the body cavity of its host. However, osmotic invasion of water must occur far quicker than ionic exchange since complete release of larvae does take place when female worms pass out into the redd along with the eggs of the fish and burst.
Molecular identity of a major antigen ofSchistosoma mansoniwhich cross-reacts withTrichinella spiralisandFasciola hepatica
Authors: Aronstein W. S. , Lewis S. A. , Norden A. P. , Dalton J. P. , Strand M. 
Published: June 2009

SUMMARYA glycoprotein cross-reactive amongSchistosoma mansoni, Trichinella spiralisandFasciola hepaticawas identified and characterized by use of monoclonal antibodies prepared againstS. mansoniglycoproteins. Four monoclonal antibodies recognized the same antigen which was one of the majorS. mansoniglycoproteins precipitated by sera of hosts infected with eitherS. mansoniorT. spiralis. This antigen was expressed inS. mansonicercariae, adult male and female worms, and eggs, and inS. haematobiumbut not inS. japonicum. Radio-immunoprecipitation and partial proteolytic digest mapping showed that the monoclonal antibodies each recognized a unique epitope. These epitopes were heat labile, sensitive to chaotropic agents, but resistant to reduction and alkylation or digestion with glycosidases, indicating that the recognition sites were amino acids and not carbohydrates. Epitopes recognized by the four monoclonal antibodies were expressed inF. hepatica, whereas only two were expressed inT. spiralis. Analysis by immunofluorescence microscopy showed that the antigen was expressed inS. mansoniin the parenchymal tissue and on the surface of the dorsal tubercles; in matureF. hepaticain the parenchymal tissue, vitelline glands and eggs; in immatureF. hepaticaonly in the parenchymal tissue and in larvalT. spiralisin the hypodermis.
Role of small mammals in the epidemiology of toxocariasis
Authors: Dubinský P. , Havasiová-Reiterová K. , Peťko B. , Hovorka I. , Tomašovičová O. 
Published: June 2009

SUMMARYStudies were conducted on the role of small mammals in maintaining toxocariasis foci in urban, rural and montane biotopes. The lowest relative density of small mammals was recorded in the urban locality and the highest in the rural and montane localities. Anti-Toxocaraantibodies were most frequently detected in synanthropic and hemisynanthropic speciesMus musculus, Apodemus agrariusandMicromys minutus– 32·0, 30·4 and 25·0%, respectively. The highest seropositivity was found in small mammals from the urban and rural localities – 22·2 and 21·6%, respectively.Toxocara caniswas most prevalent in urban stray dogs (75·0%) and least prevalent in foxes from the montane locality (7·0%). The prevalence ofToxocara catiin cats at the urban, rural and montane localities was 66·2, 65·2 and 76·9%, respectively. In clinically healthy human populations, the highest seroprevalence was detected in the rural locality (14·0%). Children of the same area were 3 times more seropositive (12·9%) than those from the urban and montane localities (4·3 and 4·0%). Our studies suggest an important role for small mammals as paratenic hosts – reservoirs ofToxocaralarvae – in maintaining toxocariasis foci. In this respect toxocariasis may be classified as an anthropopurgic focal zoonosis.
Schistosoma mansoni: an ultrastructural examination of pulmonary migration
Authors: Crabtree Jean E. , Wilson R. A. 
Published: June 2009

SUMMARYThe migration of schistosomula through the lungs of mice has been investigated at the ultrastructural level. On Days 4 and 7 post-infection schistosomula were located only within the vasculature. Newly arrived Day 4 schistosomula were highly convoluted and completely occluded vessels measuring approximately 15–25μm in diameter. By Day 7 parasites were located in pulmonary capillaries, often causing considerable distension. The subtegumentary fibrous interstitial layer was absent in elongated lung schistosomula. The minimum diameter of such parasites was 8μm, and their tegument was usually unridged and flattened against the vascular endothelium, thus resulting in close apposition of endothelial and tegumental membranes. The tight fit of schistosomula in the pulmonary capillaries implies that migration through them is both a strenuous and slow process. The migratory delay in the lungs after arrival from the skin occurs because dimensional changes are necessary for successful capillary migration.
Estimation of heritability of susceptibility to infection withTheileria parvain the tickRhipicephalus appendiculatus
Authors: Young A. S. , Dolan T. T. , Mwakima F. N. , Ochanda H. , Mwaura S. N. , Njihia G. M. , Muthoni M. W. , Dolan R. B. 
Published: June 2009

SUMMARYHeritability of susceptibility to infection withTheileria parvawas estimated from full sib families ofRhipicephalus appendiculatusticks. Male and female ticks of 2 stocks were mated singly. Nineteen full sib families of the Muguga stock and 17 full sib families of the Kiambu stock were obtained. Nymphae of these families were fed on cattle infected withT. parvaso that the ticks became replete on days 16 and 17 after infection when the blood was parasitaemic with intraerythrocytic piroplasms. TheT. parvainfections were assessed in the resultant adult ticks of each full sib group and the abundance of infection, the number of salivary gland acini infected/tick, was found to be the most useful parameter for analysis. Estimates of heritability of the susceptibility to infection withT. parvafor the Kiambu and the Muguga tick stocks were 0·24 and 0·26 respectively. Using only the data from ticks which fed on day 16, the heritability estimates were 0·39 for the Kiambu stock and 0·59 for the Muguga stock. These results indicate that tick lines of high or low susceptibility forT. parvainfection could be produced through selection.
Discrimination between Gyrodactylus salaris, G. derjavini and G. truttae (Platyhelminthes: Monogenea) using restriction fragment length polymorphisms and an oligonucleotide probe within the small subunit ribosomal RNA gene
Authors: Cunningham C. O. , McGillivray D. M. , MacKenzie K. , Melvin W. T. 
Published: June 2009

SUMMARYThe small subunit ribosomal RNA (srRNA) gene was amplified from Gyrodactylus salaris using the polymerase chain reaction (PCR), cloned, and the complete gene sequence of 1966 bp determined. The V4 region of the srRNA gene was identified and amplified from single specimens of G. salaris, G. derjavini and G. truttae. Comparison of the V4 sequences from these three species revealed sequence differences from which restriction fragment length polymorphisms (RFLPs) were predicted and an oligonucleotide probe (GsV4) specific to G. salaris designed. Digestion of the amplified V4 region of the srRNA gene with Hae III and either Alw I, BstY I, Dde I or Mbo I provided a means of discriminating between G. salaris, G. derjavini and G. truttae. The GsV4 probe was used to detect the srRNA gene from G. salaris in Southern and dot blots of the amplified V4 region. The nucleotide sequences reported in this paper have been submitted to the EMBL Data Library under accession numbers Z26942 (G. salaris), Z35128 (G. derjavini) and Z35129 (G. truttae).
Ultrastructural immunolocalization of two circulating egg antigens in miracidia ofSchistosoma mansoni
Authors: Bogers J. J. P. M. , Nibbeling H. A. M. , Singh S. Kumar , Deelder A. M. , Van Marck E. A. E. 
Published: June 2009

SUMMARYIn the present study ultrastructural immunocytochemical techniques have been used to localize the cells producing two soluble egg antigens present in the hatching fluid ofSchistosoma mansoni, using two recently described monoclonal antibodies (MAbs). In the miracidium ofS. mansoni, the one apical and the two lateral unicellular glands showed immunoreactivity for the egg antigens, using a post-embedding immunogold technique. Immunoreactivity was associated with the contents of vesicles for both the MAbs, although the intravesicular distribution was not identical. This difference in ultrastructural staining pattern provides additional evidence that the two MAbs are binding with different epitopes of the same antigen or with different antigens altogether. The finding of free unbound label around the embedded miracidium is consistent with secretion having been released from the glands.