bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolution of tissue migration by parasitic nematode larvae
Authors: Read A. F. , Sharping A. 
Published: June 2009

SUMMARYMigration by nematode larvae through the tissues of their mammalian hosts can cause considerable pathology, and yet the evolutionary factors responsible for this migratory behaviour are poorly understood. The behaviour is particularly paradoxical in genera such asAscarisandStrongylusin which larvae undergo extensive migrations which begin and end in the same location. The orthodox explanation for this apparently pointless behaviour is that a tissue phase is a developmental requirement following the evolutionary loss of skin penetration or intermediate hosts. Yet tissue migration is not always necessary for development, and navigation and survival in an array of different habitats must require costly biochemical and morphological adaptations. Migrating larvae also risk becoming lost or killed by the host. Natural selection should therefore remove such behaviour unless there are compensating benefits. Here we propose that migration is a selectively advantageous life-history strategy. We show that taxa exploiting tissue habitats during development are, on average, bigger than their closest relatives that develop wholly in the gastrointestinal tract. Time to reproduction is the same, indicating that worms with a tissue phase during development grow faster. This previously unsuspected association between juvenile habitat and size is independent of any effects of adult habitat, life-cycle, or host size, generation time or diet. Because fecundity is intimately linked with size in nematodes, this provides an explanation for the maintenance of tissue migration by natural selection, analogous to the pre-spawning migrations of salmon.
Characterization of the parasite-host cell interactions involved inTheileria parvasporozoite invasion of bovine lymphocytes
Authors: Shaw M. K. 
Published: June 2009

SUMMARYSporozoite invasion of bovine lymphocytes byTheileria parvais a pH-dependent process that occurs without the need forde novoprotein synthesis. The process was inhibited by RGD(S) peptides, fibronectin and, in the presence of serum, by antibodies reactive with fibronectin. Invasion was also blocked by a range of sulphated glycoconjugates, but treatment of lymphocytes with heparitinase did not inhibit entry. Enzymic modifications of the lymphocyte surface demonstrated that trypsin-insensitive glycoproteins containingO- andN-linked carbohydrates as well as phospholipase-sensitive molecules on the host cell surface were critical to sporozoite entry. Modification of the lymphocyte surface with NEM and DTT had only marginal effects on sporozoite binding but blocked parasite internalization. Invasion was also blocked by several antibodies which cross-reacted with sporozoite surface molecules. While only a few experimental conditions specifically blocked sporozoite binding, a wider range of reagents and treatments inhibited parasite entry. The reasons for this are discussed in terms of the nature of the zippering process that facilitates sporozoite internalization.
Density-dependent effects of Anguillicola crassus (Nematoda) within and on its copepod intermediate hosts
Authors: Ashworth S. T. , Kennedy C. R. , Blanc G. 
Published: June 2009

SUMMARYDensity-dependent effects of Anguillicola crassus larval infections in the copepod intermediate host were examined experimentally. Three species of copepods (Cyclops vicinus, C. viridis and C. fuscus) were subjected to a range of doses of larval A. crassus within infection arenas. Prevalence, intensity and parasite dispersion (variance: mean abundance) values increase and then approach an asymptote as infection dose increases. Infection parameters differ between species of copepod. Increasing temperature has a negative effect on the establishment of the parasite population within the intermediate host. Parasite-induced host mortality increases with dose. These mechanisms have the potential to regulate populations of A. crassus larvae within the copepod population and hence the whole suprapopulation.
Villus length influences habitat selection by Heligmosomoides polygyrus
Authors: Bansemir A. D. , Sukhdeo M. V. K. 
Published: June 2009

SUMMARYHeligmosomoides polygyrus is a gastrointestinal nematode whose adult distribution is restricted to the duodenal region in the small intestine of the mouse. This study tests the hypothesis that the habitat of these parasitic worms is influenced by fixed (architectural) cues in the small intestine of the vertebrate host, and that H. polygyrus adults will select microhabitats containing the longest villi. H. polygyrus adults attach by coiling around the villi, and longer villi may provide greater attachment resources. In addition, these parasites feed on the epithelial cells covering the villi and thus longer villi may also provide more food resources. Using histological methods, this study identified a gradient of villus length in the small intestine of the mouse where the longest villi were found in the duodenum and shortest in the ileum Several non-surgical and surgical treatments were used to differentially alter the overall lengths of the villi. These treatments produced a significant negative correlation between villus length and worm distribution, with the worms selecting regions with the relatively longest villi in the small intestine. Attachment and feeding sites are crucial resources for this parasite, and these data suggest that villus length may be a reliable indicator of resource quality, and that decisions on habitat suitability by H. polygyrus adults may depend on this single, topological variable.
Lipid fractions in adult Schistosoma mansoni
Authors: Smith Thomas M. , Brooks Thomas J. 
Published: June 2009

Total lipid from adult male and adult paired Schistosoma mansoni has been fractionated by thin-layer chromatography. Phospholipid, free sterol, and triglyceride were major components of both mixtures. A remarkably small amount of sterol ester was found in adult flukes considering the prevalence of this compound in mouse blood. Free fatty acids were found to be a minor component. Cholesterol was the major free sterol present.The technical assistance of Mrs Katye Ross Summerlin is gratefully acknowledged.
The influence of dietary methionine on the amino acid pool ofHymenolepis diminutain the rat's intestine
Authors: Hopkins C. A. 
Published: June 2009

The amount of [14C]methionine in the stomach, anterior and posterior intestine wall and lumen, blood and caecum of a rat, and in the anterior and posterior parts of the tapewormHymenolepis diminutain the intestine, was measured at intervals from 10 min to 10 h after feeding a meal of 2 g glucose and 37.5 mg methionine by stomach tube.Nearly all the meal left the stomach within 5 h; the amount entering the tapeworm depended on the position of the worm. That part lying in the anterior half of the intestine was subjected to a rapid influx reaching a maximum concentration of at least 8 mM within 1–3 h after the meal was administered. The level in the worm then dropped to about 20 % of the peak level, although the stomach was still emptying and the level of methionine in the intestine wall was still rising. This was a stable state, and equal to the concentration in the posterior part of the worm which was reached 2 h after the rat was fed.The reason why the anterior part of the worm should show a big influx and efflux is discussed and related to changes in concentration of methionine in the lumen. The lack of such a flux into and out of the worm further down the intestine is related to the host's homeostatic control of amino acid balance in the intestine.The results prove that dietary imbalance of amino acids affect the amino acid pool in a tapeworm for about 3 h, if it lies in the anterior of the gut. A dietary regime is suggested which should produce a prolonged effect and thereby retard growth of the worm.The weights of the parts of the worms found in the anterior and posterior half of the small intestine revealed an unexpected phenomenon; the majority of the tapeworm, by weight, lies in the anterior of the intestine for about 4 h following a meal, but in the posterior of the intestine after the stomach has emptied.It is a great pleasure to thank Miss Gillian Moore and Miss Patricia Grant for technical assistance, and Shell International Petroleum Company, London, for financial support.
Observations on the nephridial system of the cestodeMoniezia expansa(Rud., 1805)
Authors: Howells R. E. 
Published: June 2009

The nephridial system ofM. expansahas been studied using light and electron microscopy, and a number of histochemical techniques have been used on sections of the worm. The organization of the nephridial system and the fine structure of the flame cells and the nephridial ducts are described. Pores, which connect the nephridial lumen to the intercellular space of the connective tissue, exist at the junction of a flame cell and a nephridial duct. These pores may be considered nephrostomes and the system therefore is not protonephridial as defined by Hyman (1951).The epithelium lining the nephridial ducts has a structure which suggests that it is metabolically active. It is postulated that the beating of the cilia of the flame cells draws fluid into the ducts via the nephrostomes, with absorption and/or secretion of solutes being carried out by the epithelial cells of the duct walls. The function of the nephridial system is discussed.I am grateful to Professor James Brough for the provision of research facilities at the Department of Zoology, University College, Cardiff, andtoDrD. A. Erasmus for much helpful advice during the course of the work. I wish to thank Professors W. Peters and T. Wilson for critically reading the manuscript and Miss M. Williams and Mr T. Davies for expert technical assistance.I also wish to thank the Veterinary Inspector and his staff at the Roath Abattoir, Cardiff, for their kind co-operation and assistance in obtaining material.The work was carried out under the tenure of an S.R.C. research scholarship.
Observations on the scolex of Echinococcus granulosus, with special reference to the occurrence and cytochemistry of secretory cells in the rostellum
Authors: Smyth J. D. 
Published: June 2009

1. The mode of attachment of Echinococcus granulosus to the dog intestine was examined.2. In an attached worm, the scolex was found to penetrate deeply into the crypts of Lieberkühn, with the rostellum fully extended, the hooks penetrating the epithelium lightly and each sucker holding a ‘plug’ of mucous cells in its cavity.3. The expansion of the rostellar tip was aided by a muscular disk, the rostellar pad, which probably assists attachment by forcing the hooks outwards.4. The epithelium in the region of the suckers showed eosinophilic reactions which may indicate a mild host reaction.5. The existence of a small group of spindle-shaped secretory cells which form a rostellar gland, lying immediately anterior to the rostellar pad, is reported. This gland was found to be the source of secretion droplets seen to be released in vitro from the scolex region.6. The secretion droplets were found to be exceptionally labile and not preserved in the rostellar gland cells by routine fixation methods. Prolonged fixation (5–12 months) in formol (7% formaldehyde) gave excellent preservation but globules were fairly well preserved after 3 months fixation. Fixation in Baker's formol-calcium for 2 weeks followed by controlled chromation was also found to retain the secretion reasonably well but not as adequately as the prolonged fixation.7. The secretion was found to be negative to the PAS, bromo-phenol blue (with Hg), and ninhydrin-Schiff reactions. The areas adjacent to the globules gave a protein reaction and the periphery of the globules appeared dark by phase contrast microscopy.8. The secretion was weakly positive to performic acid-Schiff and gave strong reactions with Sudan Black after controlled chromation, both in frozen and wax sections. These results suggest that the secretion may be a liproprotein or a lipid-protein coacervate but it is recognized that confirmation by biochemical methods is desirable.9. The possible immunological implications of these results are discussed.This work was supported by the Australian Wool Research Committee and the U.S. Public Health Service Grant No. E. 4707–02. The technical assistance of Mrs A. L. Warrener and Mr A. B. Howkins is gratefully acknowledged.
A dosing technique and the effects of sub-lethal doses of Nosema fumiferanae (Microsporida) on its host the spruce budworm, Choristoneura fumiferana
Authors: Wilson G. G. 
Published: June 2009

SummaryVarious dosages of the microsporidian parasite, Nosema fumiferanae were fed to 12-day-old larvae of Choristoneura fumiferana using a previously undescribed bioassay capsule. A spore dose of 3 × 104 resulted in 92% infection and a significant reduction in pupal weights, adult female longevity and a mean spore concentration of 1·5 × 107/living adult. Significant mortality (68%, combined larvae and pupae) did not occur until larvae ingested 3 × 107 spores; this dose produced a mean of 1·8 × 107 spores in dead larvae and 3·6 × 107 and 4·6 × 107 spores in dead male and female pupae respectively.
The morphology and life-cycle of the oviparousOögyrodactylus farlowellaegen. et sp.nov. (Monogenea, Gyrodactylidea)
Authors: Harris P. D. 
Published: June 2009

SummaryOögyrodactylus farlowellaegen. et sp.nov., an oviparous monogenean, is described from the skin and fins ofFarlowella amazonum, a South American loricarid catfish. The Oögyrodactylidae fam.nov., containingO. farlowellae and Phanerothecium caballeroiKritsky and Thatcher, 1977, is placed with the Gyrodactylidae in the Gyrodactylidea. Although oviparous, the Oögyrodactylids are closely related to the viviparous gyrodactylids. Both families share a combination of characters, including haptor morphology, articulated marginal hooks and spike sensilla, which is not seen in other monogeneans.O. farlowellaeis similar to a hypothetical ancestor of the gyrodactylids and shows that the family arose from monopisthocotylean rather than polyopisthocotylean stock. There is a close resemblance between the reproductive system of the immatureOögyrodactylusand that of the matureGyrodactylus, suggesting that progenesis, involving the precocious maturation of oocytes, may have been important in the evolution of the viviparous genera.O. farlowellaeretains eggs individually in the ootype until embryonation is comparatively advanced. After oviposition the eggs adhere to the substrate and hatch to give a crawling, unciliated larva. These are adaptations to a host which inhabits fast-flowing streams, where the eggs and infective larvae are exposed to a constant, uni-directional water current. The life-cycle (egg to adult) is completed in 11–13 days at 27 °C.
The respiratory horns of Psychoda pupae (Diptera: Psychodidae)
Authors: Satchell G. H. 
Published: June 2009

1. The respiratory horn of Psychoda severini Tonn. subsp. parthenogenetica Tonn. is described. Within the tubular horn lies the felt chamber, which meets the horn wall at a number of thin circular regions, the pits, and communicates, through the annulated base of the horn, with the tracheal extension. This has a characteristic retiform thickening and is continuous, at the lower end, with the spiracular chamber, from which a trachea runs to the prothoracic spiracle of the imago.2. At the upper end of the tracheal extension lies the closing mechanism consisting of a lever, and a muscle surrounded by a cuticular sheath. It is suggested that the mechanism functions by compressing the tracheal extension, and that the sheath serves to protect the muscle from the action of the moulting fluid.3. The respiratory horns of fourteen of the British species of Psychoda are described, and it is shown that Ps. spreta Tonn., Ps. albipennis Zett. and Ps. trinodulosa Tonn. are like Ps. severini in possessing long lateral tubes in at least the basal half of the horn, whereas Ps. alternata Say, Ps. surcoufi Tonn., Ps. cinerea Banks, Ps. gemina Eaton, Ps. lobata Tonn., Ps. grisescens Tonn. and Ps. setigera Tonn. have only short lateral tubes. The two species Ps. phalaenoides L. subsp. elongata Tonn. and Ps. crassipenis Tonn. are alike in having a two-branched felt chamber, and Ps. brevicornis Tonn. has a flat triangular horn with a three-branched felt chamber and a cluster of air-containing tubes at each corner.4. An account is given of the development of the respiratory horn of Ps. alternata Say. The horn arises as an outgrowth from the larval prothoracic imaginal disk, and the felt chamber forms by an invagination of its posterior wall. The tracheal extension arises as an invagination of the disk and subsequently acquires a connexion to the felt chamber.5. The development is compared with that of Chaoborus plumicornis, and it is concluded that Weismann's theory of the origin of the horn from two distinct cell layers is not applicable to Psychoda.6. The various terms that have been applied to the respiratory horn are discussed, and the conclusion is reached that though none of them is satisfactory, it is premature to devise a new scheme of nomenclature.Grateful acknowledgements are due to Dr Ll. Lloyd for his help and advice in the course of this work. Some of the material was collected whilst the writer was in receipt of a grant from the Department of Scientific and Industrial Research, to whom acknowledgements are also due.
Notes on the life history of a parasitic copepod, Lernaea chackoensis
Authors: Gnanamuthu C. P. 
Published: June 2009

1. The nauplius, the metanauplius and the first copepodid larva, of Lernaea chackoensis were reared in vitro and are described.2. The four copepodid larvae obtained by artificial infection of Barbus stigma and Oryzias rubristigma are described.3. The young females infesting the adult host fishes are described, noting the changes which take place after the copulation of the female larva.4. The accelerated development of this tropica form and the need for a temporary host to complete the life cycle are discussed.
Immunity and metabolic rate: the course of notoedric scabies in rats with different metabolic rates
Authors: Leech F. B. , Spence T. 
Published: June 2009

1. Two experiments are described investigating the effects of level of metabolism on (a) resistance to, and (b) recovery from, Notoedric scabies of rats. The progress and severity of the disease was measured by weekly counts of the number of lesions; the metabolic rate in some rats was raised by administration of iodinated casein and in others was depressed by methyl thiouracil.2. In normal rats, the initial severe phase of the disease was followed by a partial recovery with survival of a smaller population of parasites.3. This recovery process in established infestations was hastened by elevation and retarded by depression of the metabolic rate.4. Resistance to the development of severe disease was enhanced by elevation and reduced by depression of the basal metabolic rate.5. The level of the residual infestation, after the severe phase of the disease had passed, was also affected by the treatment, being decreased by the higher but increased by the lower metabolic rate.
The food habits ofEntamoeba histolyticain its commensal phase
Authors: Hoare Cecil A. 
Published: June 2009

1. After a general consideration of the host-parasite relations betweenE. histolyticaand man, a case is made for the recognition of a commensal phase in the life history of this amoeba.2. This view is supported by observations on the food habits ofE. histolyticain chronic cases and carriers of human amoebiasis.3. From these observations it is evident that from 30 to 100% of trophic amoebae in such cases have ingested bacteria derived from the contents of the large bowel.
On the systematic position of the genus Deropristis, of Dihemistephanus sturionis little, 1930, and of a new digenetic trematode from a sturgeon
Authors: Cable R. M. 
Published: June 2009

Pristotrema manteri n.g., n.sp. is described from the spiral valve of the shovel-nosed sturgeon, Scaphirhynchus platorhynchus (Rafinesque), in the Wabash River, Indiana, U.S.A.A new genus, Pristicola, is erected for Dihemistephanus Little, 1930, nec Looss, 1901, with Pristicola sturionis (Little) as the type and only species.The subfamily Deropristiinae Cable & Hunninen, 1942, is re-defined to receive the genera Pristotrema and Pristicola as well as the type genus, Deropristis.The uncertain family position of the Deropristiinae is discussed without removing it from the Lepocreadiidae, although the independent status of that family may be questioned in the light of recent work.
Zinc transporter-2 (ZnT2) variants are localized to distinct subcellular compartments and functionally transport zinc
Authors: Lopez Veronica , Kelleher Shannon L. 
Published: June 2009

ZnT2 (zinc transporter-2) expression is restricted to tissues with unique zinc requirements such as mammary and prostate glands. We previously determined that ZnT2 plays a major role in zinc export from mammary glands, as women with a mutation in the gene encoding ZnT2 (SLC30A2) had an ∼75% reduction in milk zinc concentration. Two distinct human ZnT2 isoforms (∼42 and 35 kDa) are predicted to result from alternative splicing of SLC30A2. We examined the localization and function of each ZnT2 isoform, in cells generated to express ZnT2–HA (haemagglutinin) fusion proteins. The 42 kDa isoform was localized primarily to the endosomal/secretory compartment and overexpression resulted in increased zinc vesicularization. In contrast, the 35 kDa isoform is associated with the plasma membrane. Importantly, zinc transport was higher in cells over-expressing each isoform, indicating that both proteins are functional. Endogenous expression of the secretory vesicle-associated ZnT2 isoform predominates in mammary cells and expression is higher in secreting cells, whereas the smaller isoform plays a minor role in zinc export, directly reflecting the secretory function of the mammary gland. Together our data shed further light on the complex integration of cellular zinc transport mechanisms, which may be facilitated by multiple isoforms of specific zinc transporters with unique cellular functions.
Detecting SNPs and estimating allele frequencies in clonal bacterial populations by sequencing pooled DNA
Authors: Holt Kathryn E. , Teo Yik Y. , Li Heng , Nair Satheesh , Dougan Gordon , Wain John , Parkhill Julian 
Published: June 2009

Abstract
Summary: Here, we present a method for estimating the frequencies of SNP alleles present within pooled samples of DNA using high-throughput short-read sequencing. The method was tested on real data from six strains of the highly monomorphic pathogen Salmonella Paratyphi A, sequenced individually and in a pool. A variety of read mapping and quality-weighting procedures were tested to determine the optimal parameters, which afforded ≥80% sensitivity of SNP detection and strong correlation with true SNP frequency at poolwide read depth of 40×, declining only slightly at read depths 20–40×.
Availability: The method was implemented in Perl and relies on the opensource software Maq for read mapping and SNP calling. The Perl script is freely available from ftp://ftp.sanger.ac.uk/pub/pathogens/pools/.
Contact: kh2@sanger.ac.uk
Supplementary information: Supplementary data are available at Bioinformatics online.