bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intestinal migration in the life-cycle of Pseudodiplorchis americanus (Monogenea)
Authors: Tinsley R. C. , Jackson Helen C. 
Published: June 2009

SUMMARYAdults of Pseudodiplorchis americanus occur in the host's urinary bladder, the typical habitat of polystomatid monogeneans in amphibians. However, larvae which invade the respiratory tract via the nostrils then migrate to the bladder through the stomach and intestine, a route which is without precedent amongst monogeneans. Parasite transmission is correlated with the spawning of the desert toad Scaphiopus couchii (June/July in Arizona, USA) and the gut migration, which takes as little as 5 min, occurs after 26 days post-infection (p.i.). Migration occurs during the host's feeding season, and therefore the parasites normally encounter maximum digestive activity along their path. Worms transferred experimentally from respiratory tract to the digestive fluids in the gut are killed within 60 s. However, natural migration is stimulated by an unidentified host factor which triggers protective adaptations, enabling parasite survival for up to 4 h in these lethal conditions. Without this essential stimulus, migration may be delayed for over 1 year and juveniles remaining in the respiratory tract undergo no development beyond that reached at 4 weeks p.i. Rapid reproductive development is resumed immediately after migration, leading to maturation around 1 month later and progressive accumulation of embryos in utero in preparation for transmission during the next summer's rains.
Ovarian tissue in juvenile palaeacanthocephalans: Corynosoma semerme, C. strumosum and Echinorhynchus gadi
Authors: Peura Raija , Valtonen E. Tellervo , Crompton D. W. T. 
Published: June 2009

SUMMARYThe structure of the ovarian tissue in juvenile Corynosoma semerme and C. strumosum from a fish paratenic host and in the cystacanth stage of Echinorhynchus gadi from an amphipod intermediate host was investigated by means of transmission electron microscopy. The species were obtained from hosts living in the Baltic Sea. The observations indicate that ovarian development was more advanced in cystacanths of E. gadi than in juveniles of C. semerme and C. strumosum. Free ovaries were present in E. gadi with an obvious supporting syncytium and surface microvilli. The biological significance of the different stages of ovarian development in these species is discussed briefly in relation to either reproductive strategies and host specificity in definitive hosts or to the attainment of infectivity by cystacanths in intermediate hosts.
Permeability changes in the egg-shell of hookworms during development and eclosion
Authors: Matthews B. E. 
Published: June 2009

SUMMARYThe development and hatching ofAncylostoma ceylanicumandAncylostoma tubaeformeeggs in a range of potentially inimical solutions has been examined using time-lapse video micro-recording techniques. In all compounds tested the larvae developed to the active pretzel stage. The inception of activity resulted in an increase in shell permeability to water and small molecules. In anthelmintics of molecular weight (Mr) 400 development continued normally until about the time that control eggs hatched, when there was a marked decrease in larval activity and eclosion did not occur. The addition of a lowMrsurface-active agent potentiated the effect of the anthelmintic and caused larval activity to be lost earlier. The calcium inhibitor lanthanum chloride affected larval development rather than eclosion. LargeMrcompounds did not affect either development or hatching and the results suggest that the egg-shell may act as a form of sieve, allowing the essential oxygen to reach the developing larva while excluding large potentially dangerous molecules. No appreciable differences were found between the two species of hookworm examined.
Immunochemical analysis ofTaenia taeniaeformisantigens expressed inEscherichia coli
Authors: Bowtell D. D. L. , Saint R. B. , Rickard M. D. , Mitchell G. F. 
Published: June 2009

SUMMARYPreviously we reported the isolation of severalEscherichia coliclones expressing fragments ofTaenia taeniaeformisantigens as β-galactosidase fused proteins (Bowtell, Saint, Rickard & Mitchell, 1984). Here we describe the isolation of additional antigen-expressing clones from a larval cDNA library and the assignment of these clones to 7 antigen families. These were isolated with a polyspecific rabbit antiserum raised to the oncosphere. Since this serum was capable of reacting with a large number of antigens, it was important to develop techniques for rapidly determining the identity of the nativeT. taeniaeformismolecule corresponding to a cloned antigen gene. These included active immunization of rabbits with fused proteins and several techniques involving affinity purification on immobilized fused proteins. The reactivity of the antigen-positive clones with sera from humans infected with related parasites was also assessed. Finally, immunization of mice with several fused proteins failed to protect against subsequent infection, although antigens previously identified as candidate host-protective antigens (Bowtell, Mitchell, Anders, Lightowlers & Rickard, 1983) have yet to be identified in the expression library.
The presence of agglutinating antibody in the IgM immunoglobulin fraction of rabbit antiserum during experimental African trypanosomiasis
Authors: Seed J. R. , Cornille Renee L. , Risby E. L. , Gam A. A. 
Published: June 2009

The IgM levels in rabbits infected withTrypanosoma gambienseare raised. Agglutinating antibody has been found in the IgM immunoglobulin fraction of sera obtained from these infected rabbits. Agglutinating antibody was first found in the IgM fraction and later in the infection appeared in both the IgM and IgG fractions. Precipitating antibody to blood trypanosome antigens was found solely in the IgG fraction.On the basis of the data presented here a working hypothesis is developed to explain the raised IgM immunoglobulin levels found in the sera of rabbits and humans infected withT. gambiense.
The ultrastructure of the intestinal epithelium of Metastrongylus sp. (Nematoda: Strongyloidea)
Authors: Jenkins T. , Erasmus David A. 
Published: June 2009

Ultrastructural observations on the intestine of Metastrongylus sp. have shown that it is composed of a single layer of epithelial cells each with a basally placed nucleus and resting on a basement layer. The basal plasma membrane of each cell is highly infolded and at the cell apex the lateral plasma membranes of adjacent cells are thickened to form a terminal bar.The brush border consists of numerous microvilli which possess dilated tips. The tips contain a granular material and the evidence obtained suggests that they are released into the lumen indicating a form of micro-apocrine secretion. Golgi complexes, glycogen, lipid droplets and granular endoplasmic reticulum are present in the intestinal cells. The Golgi complexes are associated with the production of an electron dense body. Other inclusions are cytolysome-like in their structure. The discharge of lamellar bodies into the intestinal lumen is described and the role of the intestine in secretion, absorption, and excretion is discussed.The authors wish to acknowledge the co-operation and facilities provided by Professor J. Brough in the Department of Zoology and Mr J. H. M. Hughes (Veterinary Officer) for allowing unrestricted access to infected material at the Roath abattoir, Cardiff. Grateful acknowledgement is also expressed for the financial support given to one of us (T. J.) by the Pig Industry Development Authority. Any views expressed in this paper are not necessarily those of the Authority.The authors also wish to express their appreciation of the excellent technical assistance provided by Mr T. W. Davies.
Babesia rodhaini infections in the rat after acute primary parasitaemia
Authors: Phillips R. S. 
Published: June 2009

Babesia rodhaini remains in the blood of most rats from 2 to 12 months after the acute primary parasitaemia has subsided. By analogy with some trypanosome and malaria infections it is suggested that piroplasms may have the capacity for antigenic variation, thus allowing the parasite to survive in the host for so long albeit as a chronic infection. A population of B. rodhaini was isolated which was considerably less sensitive in passive transfer experiments to two pools of serum from recovered rats than the normal passage population.I thank Dr S. F. Barnett for his advice during the work and Dr F. Hawking and my colleagues at Mill Hill for criticizing the manuscript. This work was carried out during the tenure of an Agricultural Research Council Studentship.
The protective activity of serum from immune rats againstBabesia rodhaini
Authors: Phillips R. S. 
Published: June 2009

Sera pooled from rats which were immune toBabesia rodhainiinfection had demonstrable protective activity against the piroplasm in non-immune rats. When inoculated with parasites or close to the time of infection, antiserum caused a delay in the onset of patency but did not usually affect the course and severity of the patent parasitaemia in young rats. There were more survivors when antiserum was given in a series of small doses over a period rather than a single large inoculum at the time of infection. Serum from rats previously reinfected several times, when injected into infected rats during the early stages of patency, was followed by a rapid fall in parasite numbers. A severe secondary parasitaemia eventually ensued in these animals.I would like to thank Dr S. F. Barnett for his advice during the work and Dr F. Hawking and my colleagues at Mill Hill for criticizing the manuscript. This work was carried out during the tenure of an Agricultural Research Council Studentship.
Digestion in the tick,Argas persicus,Oken.
Authors: Tatchell R. J. 
Published: June 2009

1.Studies on the histological changes during digestion inArgas persicusreveal that the ingestion of blood is accompanied by the destruction of the existing gut epithelial cells.2.The blood remains unlysed for 2–3 days while a new epithelium develops which contains cells that secrete a saliva-fast PAS-positive colloid that causes haemolysis.3.Other epithelial cells remove the freed erythrocytic nuclei by phagocytosis.4.Most of the gut cells then absorb protein from the lumen and intracellular digestion takes place leaving pure haematin granules as the waste product of the digestion of haemoglobin.5.After the initial rapid phase of digestion only relatively few cells show signs of absorptive and digestive activity.6.Absorption of protein is accompanied by increased alkaline phosphatase activity in the microvilli of the cell border; this activity is lost once absorption finishes and digestion begins.7.Strong aminopeptidase activity can be demonstrated at the border of some of the protein vacuoles.8.In vitrotests show that the gut proteinase is active only in the acid range with peaks at pH 2·6 and 3·8 and has aKmof 0·32 % with bovine serum albumin as substrate.9.In vivodata show that digestion, after haemolysis has occurred, takes place in two phases; the first is rapid and lasts approximately 1–2 weeks and is followed by the second phase which is slow and remains constant until the next blood feed.10.The proportion of the blood meal which remains after the rapid phase of digestion is determined by the sex and developmental stage of the tick and within each category it is constant and serves, in the absence of significant fat and glycogen reserves, as a food reserve.
Studies on the tapeworm Anoplocephala perfoliata (Goeze, 1782)
Authors: Lee D. L. , Tatchell R. J. 
Published: June 2009

1. The exrectory system of Anoplocephala perfoliata has been re-described and shown to consist of a dorsal ‘network’ system of vessels to which the flame cells are connected and a ventral pair of longitudinal vessels linked only by a transverse vessel in each proglottid.2. The two excretory systems unite only in the apical ramifying vessels of the scolex.3. Alkaline phosphatase activity was demonstrated in the cuticular microvilli, the subcuticular region and in the excretory vessels.4. Non-specific esterase, insensitive to 10−4m E 600, was located in the lappets and embryonated eggs and esterases, inhibited by 10−4m E600, in parts of the cuticle and subcuticular region and parenchyma.5. Cholinesterases were found in the nervous system and in the reproductive ducts.6. Aminopeptidase was found in the neck region, in the undifferentiated proglottids, the active testes and ovaries, the male reproductive ducts and in the region of high metabolic activity in the fringe of the proglottid.
Observations on the occurrence of the plerocercoids of Triaenophorus nodulosus (Pallas, 1781) (Cestoda: Pseudophyllidea) in the perch Perca fluviatilis L. of Llyn Tegid (Bala Lake), Merionethshire
Authors: Chubb James C. 
Published: June 2009

The perch was the principal host for the plerocercoid of Triaenophorus nodulosus in Llyn Tegid.Three stages of plerocercoid development were recognized: non-encapsuled developing plerocercoids, encapsuled but living mature plerocercoids, and dead encapsuled degenerate plerocercoids.The stomach contents of the perch were analysed and planktonic crustaceans were found to be a significant part of the food from May to December. No change in diet in relation to length was found.The period of occurrence of developing plerocercoids in the perch livers was March to June. This in relation to other evidence was shown to indicate the period of infection of the perch by the procercoids.The three stages of plerocercoid development recognized were found to occur simultaneously in a few perch, and thus may represent infections acquired over three successive seasons.There was no seasonal periodicity of occurrence of the plerocercoids in the perch.All the perch examined were more or less equally infected by plerocercoids. There was no tendency for older, longer perch to be more heavily infected.One to five capsules, normally containing one plerocercoid each, occurred in the livers of the infected perch.For the perch examined there was a dynamic equilibrium between establishment of procercoids from the copepod host, and loss of plerocercoids by degeneration within the perch.The mature plerocercoids form the reservoir of infection for the definitive host of T. nodulosus, the pike.
The dynamics of the host-parasite relationship
Authors: Donald A. D. , Dineen J. K. , Turner J. H. , Wagland B. M. 
Published: June 2009

The studies presented in this paper describe the effects of control exerted by the immunological response of the host (sheep) on the developmental stages and fecundity of the parasite Nematodirus spathiger. Thirty Merino lambs, maintained worm-free, were randomly divided among three treatment groups each containing ten animals. The group 1 lambs were each given a single dose of 50,000 infective larvae, the group 2 animals were given a single dose of 130,000 infective larvae, and the group 3 animals were given twenty-five consecutive daily doses of 2000 infective larvae. Group fecundity was estimated by performing worm egg counts on daily faecal samples and development of the parasite burden was followed by carrying out differential worm counts on animals slaughtered at crucial stages during the infections. Total fecundity was greatest in group 1 and least in group 3 with group 2 intermediate. An inverse relationship between total fecundity and percentage retardation of development (percentage of 4th-stage larvae in the total worm burden) was demonstrated between the three treatment groups.The results of the studies also show that control of the parasitic infection is mediated about threshold levels of immunological responsiveness and is expressed by (1) elimination at the infective (L3) stage, (2) retardation of development at the L4 stage, (3) reduction in egg production of the adult female, (4) elimination of adult worms, and (5) discrimination against the female in both the degree of retardation in the L4 stage and the extent of elimination in the adult stage.Great variation in response was observed between individuals within treatment groups. The source of variation is attributed to differences in degree of antigenic disparity of the parasite with individual members of the heterozygous host population in which antigenic characters are not uniformly segregated.The concept of ‘fitness’ of the parasitic species was introduced into the discussion to provide a rational interpretation of the results.We are indebted to Dr S. S. Y. Young, Division of Animal Genetics, C.S.I.R.O., for advice and assistance with the statistical analyses, which were performed by Mrs M. Tonkin, and to Dr D. F. Stewart for his constructive criticism of the manuscript. Careful technical assistance was given by Mr E. Teleki and Misses Helen Giller and Berenice Merchant.
Gametogenesis and fertilization in the Mesozoan Dicyema aegira
Authors: Austin C. R. 
Published: June 2009

Evidence is presented of a periodicity of oogenesis and spermatogenesis in D. aegira. Pauses in oogenesis were detected between successions of oogonial divisions; in spermatogenesis, the intervals appeared to be longer and the pauses came before division of primary spermatocytes. Regulation of division rates was such that between two and three times as many spermatozoa as oocytes were produced.Observations indicated that spermatozoa emerged from the axial cell soon after their formation and made contact with oocytes early, often before these were fully grown. Properties of the oocyte cell membrane evidently precluded precocious sperm entry and the penetration of more than one spermatozoon.Sincere thanks are due to Dr R. B. Short, who kindly made available all the material, and to Dr S. W. Fox and Dr C. B. Metz for the excellent facilities provided. This work was supported by P. H. S. Research Grant E 4749 (Institute of Allergy and Infectious Diseases) awarded to R. B. Short, and by N.A.S.A. Grant NsG–173–62 and N.S.F. Grant G–9150. Contribution No. 019 of the Institute for Space Biosciences.
The envelope surrounding Polymorphus minutus (Goeze, 1782) (Acanthocephala) during its development in the intermediate host, Gammarus pulex
Authors: Crompton D. W. T. 
Published: June 2009

1. The envelope surrounding Polymorphus minutus during its development in Gammarus pulex has been found to be a capsule produced by a wound healing haemocytic reaction of the host. The haemocytic reaction is stimulated when the parasite stretches the connective tissue serosa of the host's gut.2. The capsule is a thin, acellular structure, consisting of a protein-carbohydrate complex like that constituting host connective tissue. This material is produced and deposited by the haemocytes.3. The ability of the haemocytes to produce this protein-carbohydrate material is considered to be the mechanism which ensures the growth of the capsule during the subsequent development of the parasite in the haemocoel.4. A second layer appears within the capsule just before the parasite reaches the cystacanth stage. This layer is believed to be produced by the parasite.5. The relevant literature is reviewed, and it appears that the envelopes surrounding all developing Acanthocephala, which have been studied to date, are probably capsules originating in the manner described above.I am very grateful to Dr P. Tate for advice and encouragement during this work, and to Dr George Salt, F.R.S., for helpful discussions and criticism of the manuscript.
The biology of Pipunculus semifumosus (Kowarz) (Diptera: Pipunculidae), a parasite of Delphacididae (Homoptera), with observations on the effects of parasitism on the host
Authors: Rothschild G. H. L. 
Published: June 2009

1. Pipunculus semifumosus (Kowarz) is an internal parasite of a number of common British Delphacidae. The life cycle and immature stages of the parasite are described.2. The external and internal effects of parasitism on the delphacid host are described. Reductions in size and genital aberrations are related to the stage at which the host is attacked, and are most marked in female delphacids.
Reappraisal of the guinea-pig as an experimental host for studies of schistosomiasis mansoni
Authors: Pearce E. J. , McLaren Diane J. 
Published: June 2009

SummaryThe guinea-pig has been reassessed as a potential laboratory host forSchistosoma mansoni. Twenty-six per cent of an infective cercarial population survive to maturity in this rodent and there are no gross fluctuations in worm burden subsequent to pairing of male and female parasites. Five day, 4-week and 6-week-old schistosomes grown in guinea-pigs have topographical features that are identical to those exhibited by similarly aged mouse worms, but different from those exhibited by rat worms. Schistosome eggs are never detected in the faeces of infected guinea-pigs, but they can be observed in the pulmonary, hepatic and intestinal tissues. Only 55% of the eggs that can be recovered from the intestinal tissues are viable, and some of these can be hatched to release miracidia that penetrate the intermediate snail host. Cercariae are sometimes liberated from infected snails, but in insufficient numbers to permit infection of naive guinea-pigs. The schistosome cycle cannot, therefore, be completed in this host. Collaterals are sometimes observed in the vasculature serving the rectum and kidneys of infected guinea-pigs and the fact that schistosome eggs are deposited in the lungs of these animals indicates that portal systemic anastomosis is a feature of the model. Pathology associated with cercarial invasion or egg deposition is not dissimilar to that described for other laboratory animals infected withS. mansoni, except that basophils participate in the inflammatory response observed in the skin and intestine.
Temporal study of acquired resistance in infections of mice withGiardia muris
Authors: Belosevic M. , Faubert G. M. 
Published: June 2009

SummarySwiss CD-1 mice infected with cysts ofGiardia murisare protected against a challenge infection. A temporal study of this phenomenon was undertaken using two different approaches. First, the time needed for mice to acquire resistance was assessed by terminating the first infection using metronidazole on days 3, 6, 12, 24 or 48. These animals received a challenge infection 7 days later. Second, the duration of the protection was determined by giving mice a challenge infection on days 30, 60, 90, 120 or 150 after the primary infection. In all cases, a significant reduction in both cyst output and trophozoite numbers in the small intestine was observed after challenge. The reduction in cyst output following challenge was similar to the reduction in trophozoite numbers. The acquired resistance of some inbred strains of mice toG. muriswas similar to that of CD-1 Swiss mice. These results show that mice can acquire a significant resistance againstG. muriseven after a short period of contact with the parasite (3 days) and that the resistance may last up to 21 weeks.