bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survey of 15 sites over 28 months for entomopathogenic nematodes (Rhabditida: Steinernematidae)
Authors: Hominick W. M. , Briscoe B. R. 
Published: June 2009

SUMMARYThe presence of entomopathogenic nematodes in soil from 15 sites on 10 sampling occasions over a period of 28 months was documented. Sites were chosen to represent habitats classified as heathland, hedgerow, roadside verge, pasture or woodland. Bioassays utilized Galleria larvae and most of the nematodes obtained were identified asSteinernema (= Neoaplectana) bibionis (Bovien). A sibling species which fails to interbreed with S. bibionis was also found at 2 of the sites. Bioassays were at 15 and 20°C and there was no significant difference in the results at these temperatures. There was no evidence for seasonality in the presence of the nematodes and at 2 sites they were found on every sampling occasion. Otherwise, sites converted unpredictably from positive to negative or negative to positive over the 28-month sampling period.
Effect of selection pressure for thiabendazole resistance on fitness of Haemonchus contortus in sheep
Authors: Maingi N. , Scott M. E. , Prichard R. K. 
Published: June 2009

SUMMARYA Strain ofHaemonchus contortusshowing moderate levels of resistance to thiabendazole (TBZ) (egg hatch assay LC50 2.1 μM) was subjected, in alternating sequence, to 5 in vitro and 4 in vivo selections with TBZ. This resulted in a significant increase in resistance (egg hatch assay LC50 2.8 μM). The isolates obtained after each combined in vitro and in vivo selection were compared in terms of egg hatch assay, establishment, net egg output, per capita egg output and degree of pathology caused in infected hosts. The increase in resistance was accompanied by a significant increase in larval establishment sheep (22 %) and was associated with more severe pathology, higher egg count and worm recovery 3 months post- infection.
Phospholipid metabolism in Plasmodium-infected erythrocytes: guidelines for further studies using radioactive precursor incorporation
Authors: Vial H. J. , Ancelin M. L. , Thuet M. J. , Philippot J. R. 
Published: June 2009

SUMMARYThe biosynthesis of phospholipids is extensive in Plasmodium knowlesi-infected simian erythrocytes due to the synthesis of membranes by this single-cell eukaryote in a host erythrocyte devoid of any pathway for lipid biosynthesis. In the present paper, we show that the incorporation of [3H]glycerol, which reflects de novo biosynthesis, is better studied at 300 μM−1 mM than at the trace doses, since this non-physiological precursor does not modify the amount of phosphatidylcholine biosynthesis from [3H]choline. Time-course incorporation of radioactive glycerol, oleate, lysophosphatidylcholine, choline, and inositol in RPMI 1640 medium containing nutrients for lipid synthesis showed that the optimum incubation time for phospholipid studies is 60–90 min, after which radioactive incorporation slows considerably. On the other hand, studies with [14C]serine revealed that incubation for 2–3 h is necessary for isotopic labelling of phosphatidylcholine via phosphatidylserine decarboxylation and phosphatidylethanolamine N-methylation. Incorporation of the various fatty acids into individual lipids was related to the molecular species composing each of them. Studies with [14C palmitoyl] lysophosphatidylcholine showed a very fast intracellular release of radioactive fatty acids, which indicates a potent lysophospholipase activity. Taken together, these data define the indispensable conditions for an experimental system suitable for further studies.
Ribosomal DNA sequences in the differentiation of pathogenic and non-pathogenic isolates ofEntamoeba histolytica
Authors: Cruz-Reyes J. A. , Spice W. M. , Rehman T. , Gisborne E. , Ackers J. P. 
Published: June 2009

SUMMARYRecombinant ribosomal DNA sequences were amplified by PCR and used as probes to perform a fingerprint analysis of total DNA from differentEntamoeba histolyticaisolates. RFLPs obtained with one of the probes, R-1, support previous proposals that pathogenic and non-pathogenicE. histolyticaare closely related, yet genotypically distinct. Another probe, R-2, while not distinguishing between the two forms ofE. hystolytica, was able to differentiate between them andE. moshkovskii, which has morphologically identical cysts and trophozoites. A third probe, BR-1, identified strain-specific RFLPs.
Microhabitat distribution and coexistence of Dactylogyrus species (Monogenea) on the gills of roach
Authors: Koskivaara M. , Valtonen E. T. , Vuori K.-M. 
Published: June 2009

SUMMARYThe Dactylogyrus fauna was studied from the gills of 293 roach between February 1988 and April 1989. Roach were caught from three interconnected lakes in Central Finland. Nine Dactylogyrus species were found. Of these the seven most abundant were used for studying the abundance of species on different gill-arches, niche breadth and niche overlap between the species. It was found that all species had a species-specific preference for certain gill-arches. The total abundances of all the species went through distinct seasonal changes, peaking during the spring and early summer. Some seasonal variation was also exhibited in gill-arch preferences. Niche breadth and species overlap were mostly higher during the period of peak occurrence of the various species, but in the case of some species they appeared to be unrelated to abundance, indicating possible niche restriction by other species. Most significant was the restriction of D. micracanthus to the fourth gill-arch during the period of peak occurrence of D. similis. Experimental work is needed to verify the reasons for variations in the microhabitat distribution of certain Dactylogyrus species.
Long-term dynamics of natural populations of Schistosoma mansoni among Rattus rattus in patchy environment
Authors: Théron A. , Pointier J. P. , Morand S. , Imbert-Establet D. , Borel G. 
Published: June 2009

SUMMARYDynamics of natural populations of Schistosoma mansoni were studied during 8 consecutive years among Rattus rattus populations from 8 transmission sites of the marshy forest focus of Guadeloupe (French West Indies). The schistosome population is over-dispersed (k = 0·119) within the murine hosts and ecological factors linked to the patchy environment may be responsible for such aggregated distribution. Analysis of the spatio-temporal variations in prevalences, intensities and abundances showed limited variations of the infection during the 8 years at the level of the whole parasite population but great spatial heterogeneity at the level of local schistosome populations. Inter-populational genetic variability linked to the degree of adaptation of this human parasite to the murine host may explain differences in transmission dynamics between the local populations of S. mansoni.
Observations on the development and survival of the free-living stages of Oesophagostomum dentatum both in their natural environments out-of-doors and under controlled conditions in the laboratory
Authors: Rose J. H. , Small A. J. 
Published: June 2009

SUMMARYEggs of Oesophagostomum dentatum in faeces deposited on grass plots from May to October developed into infective larvae. Warm wet weather facilitated development but weather conditions which caused the faeces to dry out rapidly resulted in a heavy mortality of eggs and pre-infective larvae. During the winter no development took place and the eggs died. In the early spring and late autumn a few eggs survived and developed into 1st-stage larvae but they died without developing further. In the laboratory no development took place at 4 °C but at temperatures ranging from 10 to 25 °C development into infective larvae was completed, the rate increasing as the temperature rose. Out-of-doors infective larvae survived in faeces and on herbage for 1 year under a wide range of climatic conditions including the exceptionally cold winter of 1978–79. In the laboratory, infective larvae suspended in water survived even longer at temperatures ranging from 4 to 27 °C. They were rapidly killed by continuous freezing and by desiccation when the relative humidity was less than 90%. The relationship between climatic conditions and the development and survival of the free-living stages is discussed.
Observations on the structure of the male reproductive system and spermatogenesis ofNematodirus battus
Authors: Martin Jean , Lee D. L. 
Published: June 2009

SUMMARYIn the male reproductive system ofNematodirus battusthe spermatogonia and spermatocytes are arranged upon a central rachis and the spermatocytes are characterized by the presence of cup-shaped membranous organelles which are formed in association with Golgi complexes and granular endoplasmic reticulum. Spermatozoa ofN. battusin the male nematode have an electron-dense, conical tail-like region which contains the nuclear material and an elongate cytoplasmic region which contains the cell organelles. In the uterus of the female, however, the cytoplasmic region of the spermatozoon has an amoeboid appearance and in the seminal receptacle the cytoplasmic region is dome-shaped and many of the membranous organelles have connexions with the outer membrane of the spermatozoa. Movement was not observed in spermatozoa released from the seminal vesicle of the male worm.
Host diet in experimental rodent malaria: a variable which can compromise experimental design and interpretation
Authors: Gilks C. F. , Jarra W. , Harvey-Wood K. , McLean S. A. , Schetters T. 
Published: June 2009

SUMMARYOver the past few years several experienced groups studying malaria have encountered significant problems with their particular rodent malaria–host system. This has involved, in some cases, periods during which the recovery of cryo-preserved parasite stocks and growth of bloodstream parasites was markedly inhibited and, in other cases, periods of drastically increased mortality rates. The common factor linking these incidents was that they coincided with alterations in the experimental animal diet used. in the experimental animal diet used. The inhibition of growth of cryopreserved stabilates or bloodstream parasites was abolished by supplementation with p-aminobenzoic acid (PABA) or by changing the diet used. Although the suppressive effects of diets lacking PABA on parasite growth have been known for over 30 years, the variation of PABA levels in modern laboratory animal feed concentrates is not well recognized. We have not established the exact cause of increased mortality, but it has been overcome by changing the diet used. We are documenting our experiences with this potential variable to forewarn workers in other laboratories of possible problems inherent in the use of different diets.
Gastrointestinal hormones: environmental cues for Fasciola hepatica?
Authors: Sukhdeo M. V. K. , Sukhdeo S. C. 
Published: June 2009

SUMMARYThe effects of pharmacological concentrations of several gastrointestinal hormones on the rate of sucker activity and the frequency and the amplitude of spontaneous longitudinal muscle contractions have been examined in adult Fasciola hepatica. Caerulein and serum decrease the rate of oral sucker activity; motilin decreases and CCK–PZ increases ventral sucker activity when compared to controls. Caerulein, serum and motilin significantly inhibit the frequency of contractions while bile, caerulein and motilin decrease the amplitude of contractions. These results suggest that F. hepatica can recognize and respond to certain gastrointestinal hormones and there may be adaptive value in these behavioural responses.
The ultrastructure and histochemistry of the cyst wall of Bucephalus haimeanus (Lacaze-Duthiers, 1854)
Authors: Higgins Jacqueline C. , Wright D. E. , Matthews R. A. 
Published: June 2009

Metacercarial cysts of Bucephalus haimeanus occur throughout the liver of Pomatoschistus microps, greater concentrations being found around the gall bladder, blood vessels and periphery of the liver. The cyst wall is composed of three layers, an inner granular, middle vacuolated and outer nucleated layer. The inner layer consists of three zones, an inner zone of irregularly compacted, granular material; a middle densely compacted zone and an outer moderately compacted zone. Vacuoles of the middle layer vary in appearance and appear to be discharging their contents into the cyst cavity. The cells of the outer layer are flattened and elongated with elongate nuclei but no other distinct organelles. Occasionally at the outer edge of the cyst are electron-dense cells which are in the process of degeneration. Only small amounts of collagen and very few leucocytes are associated with the cysts.The cyst wall is carbohydrate in nature containing some free aldehyde groups, galactogen and neutral mucosubstances. The inner layer appears to consist of mainly acidic mucopolysubstances and weakly acidic sulphomucins. Large amounts of protein, carbohydrate-protein complexes and DNA are also present within the cyst wall. Alkaline and acid phosphatases, ATPase, β-glucuronidase and N-acetyl-β-glucosaminidase were detected. The origin and function of the cyst wall is discussed.
The effect of previous desiccation on the ability of 4th-stage larvae ofDitylenchus dipsacito control rate of water loss and to survive drying
Authors: Perry R. N. 
Published: June 2009

The desiccation survival of 4th-stage larvae ofDitylenchus dipsacirevived from dry worm aggregations (‘wool’ larvae) was compared with that of larvae extracted from narcissus bulbs (‘bulb’ larvae). Both sorts survived desiccation well, but ‘wool’ larvae survived desiccation at various humidities somewhat better than ‘bulb’ larvae. The rate of drying of the former was more rapid than that of the latter; the ability to control water loss, therefore, does not of itself ensure survival. The number of larvae reviving decreased with repeated cycles of desiccation and hydration, and also with the increase in the period during which the nematodes were kept dry. However, this was not associated with any loss of ability to control drying. The rate of drying of ‘wool’ larvae remained unaltered irrespective of previous desiccation treatment. In contrast, the rate of drying of ‘bulb’ larvae was more rapid after an initial desiccation with the result that ‘bulb’ larvae dried at the same rate as ‘wool’ larvae. While ‘wool’ and ‘bull’ larvae differed initially in both the rate of water loss and survival, a period of desiccation eliminated only the difference in water loss.The results suggest that the rate of drying is dependent largely on physical factors. It was shown, however, that the cuticle of dead larvae was completely permeable to water in both directions. Therefore the ability to control water loss must, in some as yet unknown way, be connected with the nematode as a living system.
Alterations in erythrocyte membrane phospholipid organization due to the intracellular growth of the human malaria parasite,Plasmodium falciparum
Authors: Maguire P. A. , Prudhomme J. , Sherman I. W. 
Published: June 2009

SUMMARYThe asymmetric distribution of phospholipids in the erythrocyte membrane during the intracellular development of the human malaria parasitePlasmodium falciparumwas studied. Infected cells of high parasitaemia were treated with phospholipase A2or sphingomyelinase C, followed by isolation of the host red cell membrane using the Affigel (731) bead method. Additionally, phosphatidylserine on the surface of infected cells was probed using a phosphatidylserine-sensitive prothrombinase assay. Trophozoite-infected cells showed an increase in phosphatidylethanolamine and phosphatidylserine and a decrease in phosphatidylcholine in the outer leaflet. In addition to the changes already present in trophozoite-infected cells, schizont-infected cells showed a decrease in sphingomyelin as well as a further increase in phosphatidylserine in the outer leaflet. The results are discussed with respect to possible mechanisms and consequences of these changes.
Rickettsia-like organisms, puparial temperature and susceptibility to trypanosome infection in Glossina morsitans
Authors: Welburn S. C. , Maudlin I. 
Published: June 2009

SUMMARYMaintaining the puparial stage of successive generations of a population of tsetse 3 °C lower than normal reduced the numbers of rickettsia-like organisms (RLO) carried by emerging flies. The susceptibility of these flies to midgut infection with Trypanosoma congolense was also significantly reduced compared with control flies held at normal temperature. These results support the view that the relationship between RLO and susceptibility is quantitative – teneral flies with heavier RLO infections being more susceptible to trypanosome infection.
Synchronized erythrocytic schizogony and gametocytogenesis of Plasmodium berghei in vivo and in vitro
Authors: Mons B. , Janse C.J. , Boorsma E. G. , Van Der Kaay H. J. 
Published: June 2009

SUMMARYBoth asexual and sexual development of Plasmodium berghei was synchronized without chemical intervention using in vitro culture techniques. Combined in vivo and in vitro experiments were performed on the relationship between age, morphology and maturity of gametocytes. Schizogony took 22–23 h in the experiments. At 26 h post-invasion (p.i) the first males became capable of exflagellation. By 20 h p.i. the first gametocytes were recognizable in Giemsa-stained smears but the sex was hardly distinguishable until maturity (26 h p.i.). Survival time of gametocytes was estimated at 26 h in vitro (half-life 13 h) and the same survival time was suggested for gametocytes in vivo. Schizonts of P. berghei apparently disappeared from the peripheral circulation upon maturity, rupturing almost immediately. Mature schizonts in vitro persisted up to 48 h p.i. in non-agitated cultures. No evidence was collected for sequestration of any sub-population of gametocytes.
Enzyme variation in pathotypes of the potato cyst nematodes Globodera rostochiensis and G. pallida
Authors: Fox P. C. , Atkinson H. J. 
Published: June 2009

SUMMARYA total of 65 enzymes in the 8 European pathotypes of the potato cyst nematodes Globodera pallida and G. rostochiensis were examined by isoelectric focusing (IEF) for possible polymorphic variants which may aid rapid pathotype recognition. Quantitative variation was seen with glucose oxidase (EC 1.1.3.4), with high levels of this enzyme present in G. rostochiensis Ro3. Mannose phosphate isomerase (EC 5.3.1.8) also varied between the pathotypes with G. rostochiensis Ro4 and Ro5 differing from the other pathotypes in the relative absorbance of some bands. Phosphoglucomutase was examined on a narrow-range pH gel and additional differences to those described previously were detected.
Variability in the susceptibility of the fish host, Poecilia reticulata, to infection with Gyrodactylus bullatarudis (Monogenea)
Authors: Madhavi R. , Anderson R. M. 
Published: June 2009

SUMMARYHeterogeneity in susceptibility of guppies (Poecilia reticulata) to infection with Gyrodactylus bullatarudis was examined by comparing the establishment, reproduction and survival of the parasite on 4 inbred strains of the fish host following low and high levels of exposure to infection. The 4 strains fell into 2 broad categories of innately ‘resistant’ and ‘susceptible’ fish on the basis of strain differences in (a) the rates of growth and decay of the parasite populations, (b) the proportional occurrence of susceptible and resistant fish within each strain, (c) the average duration of primary infection, and (d) the duration of resistance to reinfection following recovery from a primary exposure. The results suggest genetic control of resistance/susceptibility traits and experiments with hybrids tentatively suggest dominance of resistance over susceptibility. The potential of the guppy – Gyrodactylus laboratory system for the investigation of the role of genetic factors in the study of host–parasite interactions is discussed.
The population dynamics of Lepeophtheirus pectoralis (Müller): seasonal variation in abundance and age structure
Authors: Boxshall G. A. 
Published: June 2009

The ectoparasitic copepod Lepeophtheirus pectoralis exhibited a regular annual cycle of abundance on its hosts. Both the incidence and intensity of infection were greatest in August or September and both declined over winter to their minimum values in April. Very similar cycles were observed in both 1972 and 1973. Analysis of the age structure of the parasite population showed that the increase in abundance coincided with the onset of the breeding season. Although females always outnumbered males the sex ratio approached unity during the breeding season, which extended from May to October. Copulating pairs were most commonly observed during this period.There was a marked bimodal peak of egg production each year, with the first mode occurring around May and the second mode around August or September. This pattern was produced by a system of alternation of generations operating within the parasite population, with a summer type generation (distinguishable by its rapid maturation rate and reduced longevity) alternating with an overwintering type of generation.
Further studies ofSchistosoma mansonicercarial stimulation by crude egg lecithin and other lipids
Authors: Austin F. , Frappaolo P. , Gilbert B. , Landis W. , Rosa M. N. da , Stirewalt M. 
Published: June 2009

The stimulus provided to cercariae by the skin fat of their definitive hosts is not the same forSchistosoma mansoniandAustrobilharzia terrigalensis.Cercariae of the former parasite are stimulated by unsaturated fatty acids, those of the latter by cholesterol.A reinvestigation of the penetration stimulant factors present in crude egg lecithin, which contains both cholesterol and free fatty acids as impurities, has shown that the latter are responsible for the stimulus inS. mansoni.The phospholipid fraction is inactive as is pure cholesterol. A little excitation of cercariae is produced by the monoglyceride fraction. These results fully confirm earlier findings.Of surface active agents other than lecithin, stimulatory activity was found only in one product which possessed carboxyl groups. Of the C18acids examined, stearic (18:0) is inactive, oleic (18:1) slightly active, linoleic (18:2) and linolenic (18:3) acids highly active. Oleic acid was shown by GC-mass spectrometry to be the most abundant acid in crude egg lecithin and is probably the main penetration stimulus present.
Anin vivomodel for the study of chemotaxis induced by Schistosomula ofSchistosoma mansoni
Authors: Chao L. P. , Jones J. T. , Kusel J. R. 
Published: June 2009

SUMMARYPeritoneal leucocytosis, with an increased percentage of eosinophils, was found in mice which had been infected withSchistosoma mansonifor 7 weeks or longer. Specific IgG against worm and egg antigens increased in peritoneal fluids and their corresponding sera respectively 5 and 7 weeks after infection. An intraperitoneal challenge with schistosomula elicited neutrophilia in all mice regardless of immune status, as well as infiltration of eosinophils and macrophages in infected mice. The secondary eosinophilia occurred in mice previously infected for 1 week or longer, whereas the infiltration of macrophages occurred only after worms from the primary infection had started laying eggs. Unlike the eosinophilia the macrophage response required infection with bisexual populations of cercariae. Injection of previously infected mice withEscherichia, TrichinellaorToxocarafailed to increase the proportions of eosinophils and macrophages. Schistosomula-induced eosinophilia could be elicited in passively sensitized mice. Intraperitoneal injection of PBS extract of adult worms elicited eosinophilia in infected mice and neutrophilia in normal mice. Two chromatographic fractions induced eosinophilia and the third only neutrophilia. The relevance of these observations to host response toS. mansoniinfections is discussed.