bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population studies on the infective stage of some nematode parasites of sheep
Authors: Donald A. D. , Leslie R. T. 
Published: June 2009

Observations have been made on the distribution of faecal deposits on a number of small fields of varying size stocked with varying numbers of sheep. These studies were undertaken to examine certain hypotheses proposed in the construction of mathematical models for the distribution of strongyloid nematode infective larvae in pastures grazed by sheep.The negative binomial distribution was found to provide a reasonable empirical description of the distribution of faeces, although there was evidence of departure from the negative binomial on the largest field.Although, tentatively, the distributions were additive with respect to the number of sheep, there was evidence of departure from additivity in respect of field area and time. The implications of these findings for the model are discussed.Significant positive correlations were found between successive time intervals in the number of faecal deposits present in individual subplots of the majority of fields. It is suggested that these arise from the tendency of sheep to use the same portion of a field for resting and rumination when heavy concentrations of faeces are deposited. The effects of this and other possible patterns of grazing and faecal deposition are discussed in relation to the intake of strongyloid infective larvae.The average number of discrete deposits of faeces on pasture produced per sheep per day was greater in flocks producing faeces in pellet form than in flocks producing soft faecal masses. However, within faeces types, there was evidence that the expected number of deposits produced per sheep per day could reasonably be assumed constant.The greater part of this work was carried out while one of us (A.D.D.) was the holder of a C.S.I.R.O. Overseas Research Studentship. For his advice and constructive criticism I am much indebted to Dr H. D. Crofton, under whose supervision this study was undertaken. My thanks go also to Professor J. E. Harris, C.B.E., F.R.S., for the provision of facilities in the Department of Zoology, and to Professor T. K. Ewer and Mr M. R. McCrea for their willing co-operation in the provision and handling of pastures and sheep at the School of Veterinary Science, Langford.Mr David Culpin and Mrs Jean Williams, of the Division of Mathematical Statistics, were responsible for programming and organizing the calculations on the CDC 3200 Computer, and were consistently helpful in proposing and criticizing tests and procedures.
Some observations on the free-living stages of Ostertagia ostertagi, a stomach worm of cattle
Authors: Rose J. H. 
Published: June 2009

Outdoor observations were made on the rate of development of the free-living stages of O. ostertagi at different times of the year, and on the migratory activities and longevity of the larvae in faeces, on herbage and in soil.The effect of temperature on the rate of development of eggs and larvae in faeces, and the effect of temperature and humidity on the longevity of eggs and larvae when separated from faeces, were studied in the laboratory.The results of these observations are discussed in relation to translation (that is, the process whereby eggs in faeces become infective larvae on herbage available to the grazing animal) and to the transmission of infection in the field.I wish to thank Mr J. F. Michel for providing the infected faeces, and Mr D. A. Griffiths for technical assistance.
Studies on the resistance of rats to the nematode Nippostrongylus muris (Yokogawa, 1920). I. Dosage-mortality relationship
Authors: Hunter G. C. , Leigh L. C. 
Published: June 2009

The LD50 of Nippostrongylus muris for outbred hooded rats has been estimated. It was higher for males than for females and this does not appear to be due to weight differences. The distribution of times of death was bimodal; the peaks corresponding to different stages in the life cycle of the worm.We wish to thank Mrs M. Whitehead for technical assistance and Mr I. McDonald for statistical analysis.
Electron microscope studies of Fasciola hepatica
Authors: Threadgold L. T. , Gallagher S. S. E. 
Published: June 2009

The ultrastructure of the parenchyma and interstitial material and the interrelations between them are described.The interstitial material, composed of a granular matrix containing fibres, is shown to ramify as a network between parenchymal cells and around organ systems. It is postulated that this structure is a ‘skeleton’.In certain localized areas the interstitial material between parenchymal cells is absent and at these points adjacent cells are united by attachment plaques (desmosomes) without tonofibrils.The possible functions of the parenchyma are considered and it is suggested that these cells are responsible not only for secreting the interstitial material, but also store glycogen and act, in the absence of a circulatory system, as a transport system for metabolites and excretory products.
A note on Polymastix Bütschli, 1884, from the colon of Periplaneta americana (Insecta: Dictyoptera)
Authors: Warhurst David C. 
Published: June 2009

A flagellate morphologically similar to Polymastix melolonthae (Grassi, 1879) was found inhabiting the colons of three out of over 200 cockroaches (Periplaneta americana) examined. A morphological description of the flagellate is given.I wish to express my thanks to Professor H. P. Moon, in whose department this work took place, for his help and advice; to my supervisor, Dr Marjorie G. Guthrie, for her advice, encouragement and constructive criticism, and also to Dr Ann Bishop, F.R.S., and Dr Elspeth W. McConnachie for their advice.
Distribution and pathogenicity of Tetrahymena limacis in the slug Deroceras reticulatum
Authors: Michelson E. H. 
Published: June 2009

The distribution of Tetrahymena limacis in its natural host Deroceras reticulatum, and the tissue responses to infection are described. Contrary to previous observations, T. limacis occurred throughout the tissues and organs of its host; the organisms were especially numerous in the kidney, the mantle shield, and in grossly visible papules on the external epithelium. Aspirates from such papules yielded numerous ciliates.T. limacis elicited a considerable pathologic response and appeared to contribute to an increase in morbidity and mortality among slugs. Tissue responses were focal (fibrotic encapsulation of isolated organisms) and diffuse (necrosis, mechanical tissue destruction, and metaplasia). Efforts to establish infection in seven species of molluscs other than D. reticulatum were unsuccessful.An extramolluscan cyst stage of T. limacis is reported for the first time. Both resting and reproductive cysts were observed. Since free-swimming trophozoites of T. limacis are not long lived, the organism is more likely an obligate rather than a facultative parasite of molluscs. Observations also suggest that slugs are infected via the respiratory pore rather than orally.It is a pleasure to acknowledge the aid and counsel given by Dr J. O. Corliss in identifying the ciliate and to Miss Lorin DuBois for technical assistance.
Helminth fauna of Nicaragua
Authors: Schmidt Gerald D. , Neiland Kenneth A. 
Published: June 2009

Cestodes collected from birds of El Recreo, Zelaya, Nicaragua are reported. Sacciuterina mathevossiani sp.nov. from Rhamphocaenus rufiventris is the only species in the genus with 32 rostellar hooks, each 22–24 μm long, and with 5–9 testes. Angularella beema (Clerc, 1906) Strand, 1928, from Iridoprocne albilinea, is partially redescribed. Also reported are Dilepis undula (Schrank, 1788) Weinland, 1858, from Turdus grayi; Anomotaenia mutabilis (Rudolphi, 1819) Baer et Bona, 1960, from Florida caerulea; Ophiovalipora lintoni (Olsen, 1937) Coil, 1950, from Butorides viriscens; Hymenolepsis pellucida Fuhrmann, 1906, from Ramphocelus paserinii and Gymnostinops montezuma; and Raillietina (R). maplestonei Southwell, 1930, from Amazona autumnalis. All are new records for Nicaragua.Thanks are expressed to Dr Thomas R. Howell, University of California who, assisted by Mr John Zeiger, collected and identified the hosts. The collecting of birds was supported in part by a grant to Dr Howell from the University of California Association in Tropical Biogeography. Gratitude is also expressed to Dr W. H. Coil, University of Kansas, who examined some of the specimens and offered helpful suggestions, and to Miss Dorothy B. Segal, Beltsville Parasitological Laboratory, for checking the records on Angularella.
A quantitative approach to parasitism
Authors: Crofton H. D. 
Published: June 2009

The frequency distribution of parasites among hosts is used as the basis of the quantitative assessment of the nature of parasitism. The host–parasite system is regarded as an ecological relationship between populations of two different species of organisms. From the overdispersed frequency distributions exemplified by the Negative Binomial distribution a specially truncated form is derived and shown to fit the data of Hynes & Nicholas (1963). The theoretical consequences are discussed and these form the basis of a definition of parasitism.I am indebted to Professor H. B. N. Hynes who so readily understood my general aims and freely provided detailed information about his work. I also have great pleasure in thanking Professor John H. Whitlock, not only for the original computing facilities which he so generously provided, but also for his many other kindnesses. I am also very grateful to Dr Charles Henderson Jun. for his work on the original computer program and to Dr Mark Westwood for his ingenuity and labours in producing a new approach to the computations.
IsRhabdospora thelohani(Laguesse) a sporozoan parasite or a tissue cell of lower vertebrates?
Authors: Bannister L. H. 
Published: June 2009

An examination with light and electron microscopes has been made of the cell type which is considered by some authors to be a sporozoan parasite,Rhabdospora thelohani, and by others to be a tissue cell of fishes and amphibians.The cell type was found in the minnowPhoxinus phoxinusin many tissue sites, including olfactory and pharygneal epithelia, kidney, eyes and brain. In some specimens it could not be found in any tissue.The cell has a thick fibrous wall, a basal nucleus, an apical mitochondrial zone, a Golgi body, and from 8 to 50 characteristic refractile rodlets.The rodlets give a negative reaction to the Feulgen test for nuclear material, but are positive to the periodic acid–Schiff stain, a test for polysaccharide. Glycogen does not appear to be present in the rodlets.Under certain circumstances the rods rupture the cell wall and may protrude in the apical region of the cell.The structures described are discussed with the evidence for and against a parasitic interpretation of the cell. It is concluded thatRhabdosporais a protozoan parasite, whose exact functional and taxonomic status is as yet unknown.I am grateful to Professor G. E. H. Foxon and to Professor P. C. C. Garnham for their encouragement, advice, and helpful criticism of the manuscript. I am further indebted to the National Spastics Society for the use of the electron microscope housed in Guy&s Hospital Medical School, and to Mr I. D. Bradbrook for his assistance with the histological techniques.
Eimeria phasiani Tyzzer, 1929—a coccidium from the pheasant (Phasianus colchicus) I. The life cycle
Authors: Trigg P. I. 
Published: June 2009

The first full account of the life-cycle of an Eimeria sp. from the pheasant is given. The strain, isolated from pheasant chicks by single oocyst inoculation is identified as E. phasiani. It is shown that there are three distinct asexual stages prior to the onset of the sexual stage.I should like to express my sincere gratitude to Dr E. U. Canning for her supervision and helpful advice, and to Professor O. W. Richards, F.R.S., for permission to work at the Imperial College Field Station. I am also grateful to Mr T. H. Blank, of the Eley Game Advisory Service, Fordingbridge, Hants, who gave day-old pheasant chicks for this study.The work was financed by a scholarship from the Agricultural Research Council.
The life-cycles and larval development of some acanthocotylids (Monogenea) from Plymouth rays
Authors: Kearn G. C. 
Published: June 2009

Acanthocotylid (monogenean) parasites inhabit the skin of rays, and the lack of cilia on the infective larvae of these parasites may be an adaptation to the host's bottom-living habits.Freshly hatched larvae must remain on the sea-bottom until a ray settles on top of them, when the larvae then have the opportunity to attach themselves to the host's ventral surface. Acanthocotyle lobianchi, which infects Raia montagui and R. clavata at Plymouth, becomes sexually mature on the host's ventral surface and rarely wanders from it, but A. elegans, which is found on R. clavata only, migrates to the dorsal surface of the host before reaching sexual maturity.The larvae of acanthocotylids use their haptoral hooklets to attach themselves to the host's epidermis, but as the parasites increase in size the load on these hooks becomes acute. This load is relieved not as in other monogeneans by the development of hamuli but by the transformation of the posterior third of the larval body into an accessory ‘pseudohaptor’.I am obliged to the Director and Staff of the Plymouth Laboratory for laboratory facilities and to Mr J. E. Green for his interest and help on many occasions.
The ecology of the free-living stages of Trichostrongylus colubriformis
Authors: Gibson T. E. , Everett G. 
Published: June 2009

The development and survival of the eggs and larvae of T. colubriformis was studied by spreading the daily faecal output of an infected sheep for 1 or 2 weeks on grass plots 6 ft square. The observations were carried out for 3 years and broadly similar results were obtained in each year. Eggs placed on the ground from November to February failed to develop. A large proportion of the eggs placed on the ground in March disintegrate but those which develop do so slowly. Infective larvae are not produced for 8–12 weeks and they are relatively short lived. As conditions become more favourable development becomes more rapid, taking 8 weeks in April 6 weeks in May and only 1 week in June, July and August. A larger proportion of the eggs develop into infective larvae and their time of survival increases. On most plots larvae did not die out until the following April. The prolonged period of snow during the winter of 1962–63 tended to preserve larvae rather than kill them. The relevance of these results to the control of trichostrongylosis is discussed and it is concluded that it would be impossible under British conditions to devise a system of rotational grazing which would satisfactorily control trichostrongylosis and at the same time ensure economic utilization of the herbage.We are grateful to Mr C. R. Phillips and Mr T. Doy for technical assistance during the course of this investigation.
Experiments on host-finding and host-specificity in the monogenean skin parasiteEntobdella soleae
Authors: Kearn G. C. 
Published: June 2009

The oncomiracidium of the monogenean skin parasiteEntobdella soleaefinds its flatfish host,Solea solea, by chemoreception. The free-swimming larva responds to a specific substance secreted by the skin of the common sole, attaches itself to this skin and immediately sheds its ciliated epidermal cells. Larvae respond in the same way to agar jelly which has been in contact with the skin ofS. solea.The oncomiracidia attach toS. soleaskin in preference to that of other soleid fishes (Buglossidium luteumandSolea variegata), pleuronectid fishes (Limanda limanda, Pleuronectes platessa) and elasmobranch flatfishes (Raiaspp.).Larvae respond strongly to isolated epidermis fromSolea soleabut show no response to the fish's cornea, indicating that the attractive substance is produced by the mucus cells in the fish's epidermis.The larvae attach with equal readiness to skin from the upper and lower surfaces ofS. solea.Thus the preponderance of young parasites on the upper surfaces of soles is due not to a preference for the upper skin but to the fact that the lower skin is in contact with the substratum and cannot be reached by the larvae.These results led to speculations on the way in which host specificity evolved in the Monogenea.I am indebted to Mr J. E. Green of the Plymouth Laboratory for setting up a tank containing infected soles and for maintaining the tank and feeding the fishes for many months.I am also grateful to the Directors and Staff of the Plymouth Laboratory and the Fisheries Laboratory, Lowestoft, for hospitality and assistance. I am particularly grateful to Mr J. Riley of the Lowestoft Laboratory for providing various flatfishes.
Resistance to primaquine inPlasmodium gallinaceum, and the problem of resistance to quinoline compounds in malaria parasites
Authors: Bishop Ann 
Published: June 2009

A tenfold enhancement of resistance to primaquine was obtained by maintaining a strain ofPlasmodium gallinaceumin a state of acute infection by serial passage of infected blood through young chicks treated with gradually increasing doses of the drug.No loss in resistance to primaquine was observed when the resistant strain was transmitted through mosquitoes, though there was some loss in resistance to the maximum tolerated dose, but not to lower doses, when the strain was maintained in a state of acute infection through untreated chicks for 41 weeks.The primaquine-resistant strain was cross-resistant to lower effective doses of pamaquin, and slightly less sensitive to quinine than the parent strain but the loss in sensitivity to chloroquine was only marginal. Sensitivity to proguanil, dihydrotriazine and pyrimethamine was normal.Attempts were made to produce a chloroquine-resistant strain ofP. gallinaceumusing different doses of the drug but no change in sensitivity was observed though the experiments were continued for more than a year. An attempt to produce a chloroquine-resistant strain by treatment of a proguanil-resistant strain with chloroquine also failed.The problem of resistance to quinoline compounds in different species ofPlasmodiumis discussed.
Observations on the life-cycle of Psilotrema oligoon (Linstow, 1887) Odhner, 1913, and on the larval stages of two other psilostome trematodes
Authors: Pike Alan W. 
Published: June 2009

The species described in this paper were found in Bithynia tentaculata from the Wentloog level, near Cardiff, South Wales. The larval stages of Psilotrema oligoon are redescribed and the taxonomy of the adults discussed. C. frondicola sp.nov. is a psilostome cercaria which has the probable flame-cell formula 2 [4 + 4 + 4 + 4 + 3 + 3] = 44. It emerges at night or during early morning, is positively phototactic and will not normally encyst on anything but vegetation. C. granocutis sp.nov. is also a psilostome cercaria; it is very small and has the probable flame-cell formula 2 [3 + 3 + 3 + 3 + 3] = 30. It emerges during the afternoon and will encyst freely on a variety of substrata.I thank Professor J. Brough of the Zoology Department, Cardiff, for the facilities provided, Dr D. A. Erasmus for supervising and encouraging this work and Dr S. M. Willmott, Director of the Commonwealth Bureau of Helminthology, for providing library facilities. This study was carried out during the tenure of a D.S.I.R. research studentship.
The fine structure of reproducing Toxoplasma gondii
Authors: Olisa Emeka G. 
Published: June 2009

1. Different shapes and forms found in Toxoplasma gondii are associated with reproduction and growth. The functions of the toxoneme and the conoid are discussed.2. A new structure, ‘lamella spiralis', is described in relation to the nucleus and the endoplasmic reticulum.3. T. gondii reproduces either by dividing into two (binary fission) or by multiple division (schizogony), and by a type of endogenous budding. In the latter case small portions pinched off from the nucleus are rounded up to form several small organisms named ‘morulae'.The author gratefully acknowledges the interest and valuable suggestions of Dr G. A. Gresham, M.D., who supervised this work; Dr J. M. Davis and Mr F. Allen, who were kind enough to read the manuscript critically, and Mr W. A. Mowlam for his technical help and advice on fixation techniques.This work was carried out during the tenure of a research scholarship awarded by the United Kingdom Department of Technical Co-operation and the Eastern Nigerian Government.
On the use of age-intensity data to detect immunity to parasitic infections, with special reference to Schistosoma mansoni in Kenya
Authors: Fulford A. J. C. , Butterworth A. E. , Sturrock R. F. , Ouma J. H. 
Published: June 2009

SUMMARYWe consider two phenomena, related to the host age-intensity profiles of parasitic infections, which have been suggested to be indicative of acquired immunity: (i) a lower age of peak intensity among more intensely infected hosts; and (ii) a decline with age in the dispersion of the distribution of parasites between hosts. We demonstrate that these phenomena occur among Kenyan schoolchildren infected with Schistosoma mansoni, although the magnitude of both is small. We also examine the mathematical models underlying these predictions and conclude that both phenomena are possible in the absence of acquired immunity or, indeed, in the absence of any density-dependent effect. In our opinion, insufficient attention has been focused upon mathematical models, describing the null hypothesis, i.e. density-independent models. In particular, we regard the usual assumptions made for the two stochastic components of these models, describing the heterogeneity between hosts and the probabilistic nature of infection and death of parasites, as too rigid and unrealistic. We demonstrate that deviation from these assumptions undermines the qualitative distinctions between models which describe acquired immunity or density dependence and those which are density-independent.
Lectin binding to secretory structures, the cuticle and the surface coat ofToxocara canisinfective larvae
Authors: Page A. P. , Rudin W. , Maizels R. M. 
Published: June 2009

SUMMARYToxocara canisinfective larvae are known to produce abundant glycosylated molecules which may be found associated with the surface or secreted into their environment. Using a range of fluorescein-conjugated and gold-conjugated lectins, the localization of particular carbohydrates was defined on the surface of live parasites, and internally at the ultrastructural level. Surface exposure ofN-acetyl galactosamine andN-acetyl glucosamine was deduced by binding of FITC-conjugatedHelix pomatia(HPA) and wheat-germ agglutinins (WGA). These sugars appear to be associated with a densely staining surface coat as conventional immuno-electron microscopy procedures dissipate this coat and reveal no surface binding site for these lectins. However, by using cryo-immuno-electron microscopical (C-IEM) techniques, the surface coat is retained and can be shown to bind WGA. The fluorescent lectins also revealed strong WGA binding to the secretory and amphidial pores, while the buccal opening and the cuticular alae bound HPA. Corresponding results were obtained at the ultrastructural level. Thus, HPA bound to the electron-dense area of the cuticle, areas of local cuticular thickening such as the alae and buccal labia, as well as to the oesophageal lumen. WGA also bound to the thickened cuticle of the alae and the buccal opening, but showed no reaction to either the electron-dense layer of the cuticle or the oesophageal lumen. Unlike HPA, WGA did bind specifically to the secretory column contents and the electron-dense regions of the lips associated with the chemosensory amphids. The compartmentalization of the sugarsN-acetyl galactosamine andN-acetyl glucosamine, their sources and routes of surface expression and the possible association with the TES glycoprotein antigens are discussed.