bluuebunny/crossref_metadata_2025_split huggingface dataset:
Questions in digenean systematics and evolution
Authors: Gibson D. I. 
Published: June 2009

SUMMARYSince the work of Dujardin (1845), attempts have been made to decipher acceptable divisions of the trematode groups at higher taxonomic levels, and yet there is still no generally accepted classification of the higher taxa of the Trematoda as there are for other groups of parasitic worms, such as the Monogenea, Cestoda, Nematoda and Acanthocephala. Why is it that workers with a wide knowledge of trematode systematics, such as Dollfus, Stunkard, Manter and especially Yamaguti, have felt unable or unwilling to comment in detail upon the phylogenetic relationships within the group at higher taxonomic levels? One of the main reasons for this state of affairs lies in the fact that, generally speaking, the group is not easily split into major subgroups by obvious, non-homoplasious morphological characters. Early attempts at division, based upon sucker arrangements, i.e. monostome, distome, amphistome and gasterostome, are not satisfactory, as distomes form the vast majority of the Digenea and both monostomes and amphistomes are certainly polyphyletic. In addition, the picture within the Digenea is complicated by the group's complex life-history patterns. Whereas early classifications all tended to be based upon adult (marital) morphology, life-history patterns are given great weight by workers such as Pearson (1972) and Bozhkov (1982). The cercarial morphology is considered the dominant feature in the classification of the group presented by La Rue (1957) and is emphasized in the phylogenetic relationships between the subgroups recognized by Cable (1974). Odening (1961), following an earlier suggestion of Lebour (1912), presented a classification, the major divisions of which were based upon the daughter-parthenita (i.e. the redia or daughter-sporocyst), a stance which he later found untenable (Odening, 1974). Consequently, the wealth of conflicting data from these and other sources has deterred the presentation both of classifications and speculations on evolutionary relationships. The classification of Odening (1974) and the recent cladistic analysis of Brooks, O'Grady & Glen (1985b) utilized data from all of the life-history stages. As the classification of Brooks et al. (1985b) is the most recent, and readily available in English, it must be a serious contender in terms of general acceptance. If it is accepted, then one would hope that this will be on its merits rather than because of its availability or the lack of viable alternatives; but, as discussed below, it is easy to find fault with this classification when it and its premises are examined in detail.
Eimeria tenellasporozoites: the method of excystation affects the surface membrane proteins
Authors: Wisher M. H. , Rose M. E. 
Published: June 2009

SUMMARYEimerian sporozoites can be recovered from intestinal washings after oral administration of oocysts to chickens but suspensions of sporozoites are usually prepared in the laboratory by incubation of sporocysts or fractured oocystsin vitro, at body temperatures, with relatively high concentrations of trypsin and bile salts. Since these agents affect membrane structure, the surface membrane of proteins ofEimeria tenellasporozoites excystedin vivoandin vitrohave been compared. Surface radio-iodination followed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) showed that more125I was incorporated into polypeptides on sporozoites excystedin vivothan on sporozoites excystedin vitro. The125I-polypeptide profile of sporozoites excystedin vivowas more resistant to subsequent incubation with pure trypsin than that of sporozoites excystedin vitro, but incubation with bile salts resulted in the loss of some iodinated polypeptides from both preparations of iodinated sporozoites. Reaction with combinations of crude trypsin and bile salts led to the lysis of sporozoites. The method of excystation had no effect on the reaction of convalescent chicken serum with Western blots of sporozoites but the results of immunofluorescent staining carried out with mouse monoclonal antibodies indicated that the structure of the cell surface was altered and some antigenic determinants were lost from sporozoites excystedin vitro. In contrast, neither the infectivity of sporozoites determinedin vivo, nor their invasion of cultured cells was changed by the method of excystation.
Measurement of malarial infectivity of human populations to mosquitoes in the Madang area, Papua New Guinea
Authors: Graves P. M. , Burkot T. R. , Carter R. , Cattani J. A. , Lagog M. , Parker J. , Brabin B. J. , Gibson F. D. , Bradley D. J. , Alpers M. P. 
Published: June 2009

SummaryThe proportion of blood meals taken on humans which are infectious to mosquitoes in the Madang area, Papua New Guinea was estimated by two methods. In the first, laboratory rearedAnopheles farautiwere fed on individuals of all ages at village surveys. The results showed that 3·8% of people were infectious and that the mean percentage of mosquitoes which became infected by feeding on these people was 37·9%. From the average proportion of mosquitoes infected, the probability that a mosquito feeding on a human would pick up infection was 0·013±0·005. In the second approach mosquitoes were fed on identifiedPlasmodium falciparum, P. vivaxandP. malariaegametocyte carriers. The results indicated that 46% of gametocyte carriers were infectious and that the mean probability of a mosquito becoming infected after feeding on a gametocyte carrier was 0·151±0·029. Gametocyte prevalence rates in all ages measured over 18 months in three villages averaged 3·3%P. falciparum, 4·0%P. vivaxand 0·7%P. malariae, totalling 8·0±0·7%. Combining gametocyte prevalence rates with the probability of a mosquito becoming infected from a gametocyte carrier, the probability of a mosquito becoming infected following a blood meal on a member of the human population was estimated to be 0·012±0·003.
Expression of circumsporozoite proteins revealedin situin the mosquito stages ofPlasmodium bergheiby the Lowicryl-immunogold technique
Authors: Hamilton A. J. , Davies C. S. , Sinden R. E. 
Published: June 2009

SummaryA monoclonal antibody against the circumsporozoite proteins of thePlasmodium bergheisporozoite was used to trace the synthesis and expression of these proteins, via the Lowicryl immunogold technique, within the developing oocyst. The proteins were detected on the endoplasmic reticulum of the oocyst and were present in the sporozoite membranes at the point of their formation.
Some observations on egg production and autoreinfection ofReighardia sternae(Diesing, 1864), a pentastomid parasite of the herring gull
Authors: Banaja A. A. , James J. L. , Riley J. 
Published: June 2009

Egg production byReighardia sternae, implanted at various stages of maturity into the interclavicular air sacs of captive gulls, is described.Females produce only 2900 eggs per lifetime over a short patent period of 1–3 days. The problem of a direct life-cycle in relation to this unusually low fecundity is discussed, and speculation is advanced concerning a possible parasitic behavioural trait which could facilitate direct transmission. The hazards of the latter are also offset by auto-reinfection.
Eimeria tenella, E. acervulina and E. maxima: studies on the development of resistance to diclazuril and other anticoccidial drugs in the chicken
Authors: Chapman H. D. 
Published: June 2009

SummaryResistance to diclazuril was induced by 10 passages of the Houghton strains of Eimeria acervulina and E. tenella in chickens given progressively greater concentrations of the drug. This resistance was, however, not complete since the drug retained some efficacy against the drug-passaged lines. Attempts to passage the Houghton strain of E. maxima in birds medicated with concentrations of diclazuril greater than 0·016 parts per million (ppm) were unsuccessful and after 10 passages at this concentration resistance had not developed. Resistance to methyl benzoquate developed after 6 passages of E. tenella in medicated chickens but resistance to amprolium was only partial after 10 passages. The pathogenicity of diclazuril- and amprolium-resistant lines of E. tenella was lower than that of the parental line. Diclazuril was effective against lines of E. tenella resistant to amprolium, arprinocid, clopidol, dinitolmide, halofuginone, methyl benzoquate, monensin and robenidine.
Cercarial emergence of Proterometra macrostoma and P. edneyi (Digenea: Azygiidae): contrasting responses to light: dark cycling
Authors: Lewis M. C. , Welsford I. G. , Uglem G. L. 
Published: June 2009

SummaryProterometra macrostoma and P. edneyi infect the same snail host, Goniobasis semicarinata, but different fish hosts in their life-cycles. Cercariae of P. macrostoma complete development in sunfish, those of P. edneyi in darters; fish become infected when they ingest free-swimming cercariae as ‘prey’. Laboratory and field experiments were designed to test the hypothesis that light: dark (L: D) cycling regulates emergence of both species. Under L: D cycling conditions, P. macrostoma emerged in the dark and P. edneyi in the light. These emergence patterns resulted from differential sensitivity to light and dark. In the laboratory and field, reversing the light and dark periods resulted in corresponding alterations in emergence patterns of both species. Both species emerged in constant light and constant dark, but their emergence patterns were altered. Emergence patterns may represent adaptations that make the cercariae more susceptible to ‘predation’ by their respective fish hosts.
Developmental changes in proteins and glycoproteins revealed by direct radio-iodination of viableTaenia saginatalarvae
Authors: Joshua G. W. P. , Harrison L. J. S. , Sewell M. M. H. 
Published: June 2009

SummaryDirect surface I radio-isotope labelling techniques and SDS—PAGE analysis were used to compare the proteins and lentil—lectin adherent glycoproteins of the bovine stage of viableTaenia saginatalarvae at three points in their development, the invasive oncospheres, immature (4-week-old) and mature (12 to 16-week-old) cysticerci. Some proteins and glycoproteins were present on all three of the ages of the parasite examined but there were also distinct age-specific proteins and glycoproteins detected on oncospheres and 4-week-old cysticerci and a marked difference between the protein/glycoprotein profiles of the parasite was apparent at these earlier stages of development and the mature cysticerci. The latter were characterized by the presence of high, 160–200 kDa molecular weight, lysine rich, glycoproteins, whereas small 16 and 18 kDa glycoproteins and a reduction-sensitive 23 kDa glycoprotein were first detected on 4-week-old immature cysticerci. Antigenic characterization of the isotope-labelled proteins and glycoproteins by immunoprecipitation against a panel of clinically defined bovine sera combined with SDS–PAGE analysis indicated that relatively few proteins were precipitated by sera fromT. saginata-infected cattle as compared to the glycoproteins. However, both protein and glycoprotein antigens of possible protective and/or diagnostic significance were identified from oncospheres and cysticerci.
Antibody responses of rodents to a tegument membrane preparation from adultSchistosoma mansoni
Authors: Roberts Shirley M. , Boot C. , Wilson R. A. 
Published: June 2009

SummaryA preparation highly enriched in tegument membranes from adult worms has been used to probe rodent responses to schistosome surface antigens. All exposure regimes in mice stimulated levels of anti-tegument IgG, measurable by ELISA. Plateau levels of circulating antibody attained were similar after mixed-sex and male-only infections, and vaccination with tegument membranes. Female-only infections and exposure to irradiated cercariae stimulated lower levels of anti-tegument antibody. Responses in rats were similar, but occurred more rapidly, probably due to the large initial parasite exposure. Although both mice and rats could be stimulated to produce high levels of anti-tegument antibody by multiple vaccination, consistent protection against a challenge was not obtained. Paradoxically, rats and mice vaccinated with irradiated cercariae developed low levels of antibody to tegument membrane antigens but were highly resistant to challenge. It was concluded that, in the range of sera examined, antibody responses to schistosome tegument membranes did not correlate with the immune status of the host.
A comparative evaluation of snail sampling and cercariometry to detect Schistosoma mansoni transmission in a large-scale, longitudinal field-study in Machakos, Kenya
Authors: Ouma J. H. , Sturrock R. F. , Klumpp R. K. , Kariuki H. C. 
Published: June 2009

SummaryIn an operational Schistosoma mansoni field-study in an area of about 20 km (population approximately 8000), transmission detection by simple snail sampling was compared with cercariometry. Between 1985 and 1987, 62 field sites were sampled at fortnightly intervals. Of a total of 2758 field observations, 89.8% gave full snail data; 64.4% full cercarial data; and 61.7% complete data for both methods. The complete data sets showed significant but not strong correlations between Biomphalaria pfeifferi (total and infected with S. mansoni or other trematodes) and cercarial (S. mansoni and non-human) recoveries. Non-human (but not S. mansoni) cercarial recovery decreased with deteriorating cercariometry filter quality. Both snail and cercarial recoveries diminished significantly with increasing water flows at the time of collection. Many samples yielded infected snails or cercariae, but not both, and neither method detected significantly more transmission sites. The method of choice for detecting transmission in a large-scale field-study depends on logistical and financial considerations. Relatively simple snail sampling allows quick, cheap and widespread data collection adequate for most purposes but more complicated cercariometry is still valuable for specific, small-scale studies.
A preliminary assessment of the feasibility of evaluating promising antifilarials in vitro against adult Onchocerca volvulus
Authors: Comley J. C. W. , Szopa T. M. , Strote G. , Buttner M. , Darge K. , Buttner W. 
Published: June 2009

SummaryThe suitability of motility indices and tetrazolium-based colorimetric assays for the determination of the viability of adult Onchocerca volvulus after in vitro exposure to potential macrofilaricides has been examined. Experimentation showed that both techniques could be applied to adult O. volvulus, although the variability between individual worms necessitated the use of large experimental groups. The potential of using cut anterior tips of female O. volvulus for screening was also investigated. These were shown to give reasonably consistent motility indices, and drug effects were discernible even after 72 h in vitro culture. Application of these viability criteria to studies on the short-term in vitro survival of intact male and female O. volvulus incubated in Eagles MEM plus serum, under 5% CO2 in air, showed this medium to be suboptimal with a greater than 50 % loss of worm viability within 144 h of nodulectomy. Males isolated by the collagenase technique were shown to be significantly less viable than dissected males, by both motility indices and tetrazolium reduction. The results highlight the need to use either dissected males, or in the case of females, the need to minimize exposure to collagenase solution. A possible mechanism for selecting a more uniformly viable female worm population is discussed. Examination of the in vitro effects of CGP 20376 using these viability criteria/assay systems showed some delayed suppression of worm motility, but after 120 h in vitro CGP 20376 was not macrofilaricidal against male or female O. volvulus. Male worms were also implanted subcutaneously into gerbils. Treatment of these animals with CGP 20376, with autopsy 2 weeks later, resulted in a small macrofilaricidal effect (28% worm death). Some reduction in the motility of living worms recovered from CGP 20376-treated gerbils was also evident. Good survival of control worms recovered 2 weeks post-implantation suggests that male O. volvulus might survive longer subcutaneously. The prospects for undertaking meaningful drug evaluations against O. volvulus in vitro (and in vivo in rodents) is therefore promising, but because of parasite availability will probably be limited to those compounds which have shown potential in other filarial test systems.
Relations between resistance to chloroquine and acidification of endocytic vesicle of Plasmodium berghei
Authors: Mahmalgi J. , Veignie E. , Prensier G. , Moreau S. 
Published: June 2009

SummaryIn order to visualize low-pH compartments of Plasmodium berghei strains we have used a basic congener of dinitrophenol, 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine (DAMP) which concentrates in acidic compartments, and can be detected by immunocytochemistry with anti-dinitrophenol antibodies. We have demonstrated that in a P. berghei chloroquine-sensitive strain (N strain), DAMP accumulates in the endocytic vacuoles where haemoglobin degradation is occurring. These compartments which have recently been shown to concentrate 4-aminoquinoline drugs (Moreau, Prensier, Maalla & Fortier, 1986) have an acidic pH. Conversely DAMP was found scattered all over the cytoplasm in a P. berghei chloroquine-resistant strain; the same phenomenon was previously observed (Moreau et al. 1986) in the localization of a 4-aminoquinoline on this same strain. Monensin-induced swelling of acidic compartments (Boss & Morre, 1984) was used as a complementary method for the determination of low-pH compartments on P. berghei strains. All the data reported here suggest that chloroquine resistance in P. berghei RC may be related to an impairment in the acidification of endocytic vesicles.
Egg production inBrugia pahangi(Nematoda: Filarioidea)
Authors: Delves C. J. , Rees H. H. , Howells R. E. 
Published: June 2009

SummaryOogenesis inBrugia pahangihas been studied by means of the aceto-orcein chromosomal squash technique and light-microscope autoradiography. The use of colchicine has demonstrated a 2–3 mm terminal germinative zone within the ovary, in which continuous and rapid mitotic division of germ cells occurs. In 80% of the gonads, oocytes within a 1–2 mm length of the ovary proximal to the germinative zone were at the prophase of meiosis I. Primary oocytes with markedly less condensed chromatin, apparently interphase cells, were observed in the corresponding region of the ovary in the remaining 20% of material examined. A cyclical or phased development of primary oocytes is suggested. Autoradiographic studies, concerned with the incorporation of [5-3H]uridine into germ cells ofB. pahangi in vitro, further suggest that the onset of meiotic prophase is associated with the initiation of high RNA synthetic activity. Following meiotic prophase, oocytes complete meiosis I before entering a period of growth during which the chromatin material is decondensed. Recondensation of chromosomes prior to meiosis II is only observed after fertilization within the seminal receptacle. On completion of meiosis II, with the extrusion of a polar body, the haploid chromosome complement of the female unites with that of the male, re-establishing the diploid number of the zygote (2n= 10).
Effect of the nematicide oxamyl on lipid utilization and infectivity inGlobodera rostochiensis
Authors: Wright D. J. , Roberts I. T. J. , Evans S. G. 
Published: June 2009

SummaryAt field rates (ca 0·1–10 μg active ingredient/ml), non-fumigant nematicides such as oxamyl do not kill plant-parasitic nematodes directly but act by impairing neuromuscular activity. The present study has shown that neutral lipid levels in 2nd-stage (infective) juveniles ofGlobodera rostochiensis, which had been incubated with the oximecarbamate nematicide oxamyl (1 μg a.i./ml) for between 8 and 35 days, were significantly (P< 0·05) greater when compared with controls maintained in water alone. The difference between treatments was found to be due principally to changes in the lipid content in the posterior half of the body which appears to act as the major long-term lipid store. When nematodes were allowed to recover for 72 h following incubation for 35 days with oxamyl, their infectivity was not significantly (P> 0·05) different from that of controls. This work is discussed in relation to the action of oxamyl and similar nematicides and to the use of controlled-release formulations as a means of increasing their efficacy.
Schistosoma mansoni:stage-dependent damage afterin vivotreatment with praziquantel
Authors: Shaw M. K. 
Published: June 2009

SummaryThein vivoeffects of a single, subcurative dose (200 mg/kg body wt of mouse) of praziquantel on the structure of the tegument and subtegumental tissues of juvenile (21-, 26- and 30-day-old) and adultSchistosoma mansoniare described. In juvenile worms praziquantel caused only moderate damage to both the tegument and subtegumental tissues although the degree of drug-induced damage was related to both the sex of the worms and to the developmental status of each individual worm. In general, male worms exhibited more extensive and longer lasting surface damage than females. However, the level and extent of the changes increased as the worms became more developmentally advanced with adult worms showing extensive damage to the tegument and vacuolization and disruption of the subtegumental tissues. The possible correlation between the stage-dependent changes in susceptibility to praziquantel and age-related changes, particularly in the phospholipid composition of the outer tegumental membrane is discussed.
A larval paralysis assay for the detection of thiabendazole resistance in trichostrongyles
Authors: Sutherland I. A. , Lee D. L. 
Published: June 2009

SummaryInfective-stage larvae of trichostrongyle nematodes, either resistant or susceptible to thiabendazole (TBZ), were incubated in eserine, an acetylcholinesterase inhibitor. Paralysis occurred in larvae treated with eserine but significant differences were observed in the percentage of larva immobilized between TBZ-resistant and TBZ-susceptible strains of the nematodes. These differences are probably related to the presence of higher levels of acetylcholinesterase in the TBZ-resistant strains than in the susceptible strains. This could be used as a rapid and inexpensive method of detecting resistance to TBZ in trichostrongyles.
Changes in the messenger RNA population during sporulation of Eimeria maxima
Authors: Ellis J. , Thurlby T. 
Published: June 2009

SUMMARYMessenger RNA has been extracted from oocysts of Eimeria maxima. Using the techniques of in vitro translation and SDS–polyacrylamide gel electrophoresis, we have been able to show that major changes in gene transcription occur during sporulation. Following an overall reduction in the abundance of many mRNAs, several genes identified as the result of an increase in the abundance of their transcripts, are highly expressed during the latter stages of sporulation. A study of two genes whose transcription is down-regulated has provided evidence which shows that both single copy and repetitive sequences are regulated during sporulation of the oocyst.