bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on muscle cells isolated from Schistosoma mansoni: a Ca2+-dependent K+ channel
Authors: Blair K. L. , Day T. A. , Lewis M. C. , Bennett J. L. , Pax R. A.
Published: June 2009

Muscle cells from adult male Schistosoma mansoni have been isolated using a combination of papain digestions and mechanical dissociation procedures. The muscle fibres isolated in this way lacked nuclei but they did contract and relax in response to high [K+], a response which was blocked in the presence of Co2+. From this we conclude that the isolation procedure yields viable muscle fibres useful for physiological studies. Patch-clamp recordings taken from the isolated fibres show a variety of discrete ionic conductances. In inside-out patches one prominent channel was a Ca2+-activated K+ channel with a conductance of 195 pS and a selectivity greater than 10:1 for K+ over Na+, Cs+ or NH4+. Percentage open time was dependent on [Ca2+] at the intracellular face. With [Ca2+] at 1 μM or greater percentage open time was > 95%; at 0.1 μM it was < 2%. No voltage sensitivity could be detected in the voltage range from –50 to –10 mV membrane potential. Ba2+ (10 mM), but neither tetraethylammonium nor 3,4-diaminopyridine blocked the channel from the intracellular face. This Ca2+-activated K+ channel in the muscle membrane of this acoelomate animal is similar in most respects to the maxi-K+ channels which have been described in a variety of cells from more highly evolved animals.
Relationship between faecal egg count and worm burden of Opisthorchis viverrini in human autopsy cases
Authors: Sithithaworn P. , Tesana S. , Pipitgool V. , Kaewkes S. , Pairojkul C. , Sripa B. , Paupairoj A. , Thaiklar K.
Published: June 2009

The relationship between faecal examination for egg output and worm burden of Opisthorchis viverrini in man of 181 autopsy cases from Northeast Thailand is described. Diagnosis of the parasite infection by stool examination for the presence of eggs was less sensitive than the worm recovery technique. Using Stoll's dilution and formalin–ether technique, no eggs were detected in the faeces of 20 cases harbouring low worm burdens (< 20 worms). The quantitative faecal egg count by Stoll's dilution technique showed a strikingly close positive correlation with the number of worms recovered (r = 0·96, P < 0·001) indicating a strong linear association between eggs per gram of faeces (epg) and worm burden. The number of epg per worm was inversely correlated to the worm burden (P < 0·001), suggesting that density-dependent constraints on fecundity could operate to restrict egg output in heavy infections. The accuracy of egg counts for estimating worm burden and its relevance to parasite epidemiological research are discussed.
Electrophoretic studies on enzymes of diploid and triploid paragonimus westermani
Authors: Agatsuma Takeshi , Habe Shigehisa
Published: June 2009

An enzyme analysis of diploid and triploid Paragonimus westermani was conducted using starch gel electrophoresis. In total, 16 enzymes, probably encoded by 18 loci, were studied for 3 populations of the diploid form sampled from 2 localities, and 4 populations of the triploid form from 4 localities. Comparison of the enzymes of the triploid and the diploid digeneans showed 5 different patterns; diaphorase (EC 1.6.2.2), glutamic-oxaloacetic transaminase (EC 2.6.1.1), hexokinase (EC 2.7.1.1), leucylglycylglycine aminopeptidase (EC 3.4.1.3), and phosphoglucomutase (EC 2.7.5.1). On the basis of the numbers of bands and their patterns, all individuals of the triploid are probably heterozygous at each of these 5 loci and homozygous at the remaining 13 loci. The occurrence of fixed heterozygotes found in triploid populations cannot be easily explained by only a single mutation. It is suggested that the variability may have been introduced by hybridization with a different sub-species or a closely related species and may, thus, have been maintained since the time of the origin of triploids.
Praziquantel treatment of Biomphalaria glabrata infected with Schistosoma mansoni– influence on snail fecundity
Authors: Riley E. M. , Chappell L. H.
Published: June 2009

Praziquantel, administered over a 72 h period in the food of mature Biomphalaria glabrata harbouring 7-week-old Schistosoma mansoni infections, dramatically reduced the numbers of cercariae shed. Doses of 20–30 μg/g body weight (including shell weight) reduced shedding by 85–95% over 5 weeks before recovery was evident. Suppression of cercarial shedding in these infections was accompanied by the temporary recovery of the snail reproductive regression due to S. mansoni infection. Snail fecundity was subsequently re-suppressed 2 weeks prior to recovery of the parasite as evidenced by a resumption of cercarial shedding. Praziquantel destroyed mature and developing cercariae within the daughter sporocysts but had no apparent effect on daughter sporocysts; this may account for the eventual resumption of cercarial production. Reproductive failure of the snail is apparently related to the latter stages of cercarial development specifically. Reproductive recovery did not occur when snails were infected as juveniles or when mature-infected snails harboured 12–5 week i.e. older infections: drug treatment temporarily inhibited cercarial production but no snails produced eggs.
Gametogenesis and fertilization inDirofilaria immitis(Nematoda: Filarioidea)
Authors: Delves C. J. , Howells R. E. , Post R. J.
Published: June 2009

Gametogenesis inDirofilaria immitishas been studied principally by means of the aceto-orcein chromosomal squash technique, but with additional ultrastructural observations. A terminal germinative zone, in which a continuous and rapid division of germ cells occurs, has been identified in the gonoduct of both male and female worms. Approximately 20% of cells within these germinative zones were in arrested mitotic division following the incubationin vitroof excised gonads in 0·01% colchicine for 4 h. All primary spermatocytes within a 1–2 cm length of the testis proximal to the germinative zone were at the prophase of the 1st meiotic division. In the corresponding region of the ovary, the primary oocytes were similarly at the prophase of the 1st meiotic division in 75% of female worms examined but in the remaining 25% all primary oocytes possessed markedly less condensed, probably interphase nuclei. A possible hormonal control of the cyclical development of primary oocytes, but not primary spermatocytes inD. immitisis suggested. In most of the remaining length of the gonoducts beyond this region of cells at meiotic prophase, the chromatin material of both primary spermatocytes and oocytes is decondensed. Recondensation of chromosomes in the spermatocytes is observed just prior to entry into the seminal vesicle, where meiosis I is completed and meiosis II takes place. In the primary oocyte, completion of meiosis only occurs after fertilization within the seminal receptacle by an entire male gamete. Following the 2 meiotic divisions in the oocyte and subsequent extrusion of the 2 polar bodies, the haploid chromosome complement of the female unites with that of the male, re-establishing the diploid number of the zygote (2n= 10). Male chromosomes within the oocyte remain visible throughout late oogenesis and fusion occurs without the formation of pronuclei.
Structure of the pinworm (Oxyurida: Nematoda) guild in the hindgut of the american cockroach, Periplaneta americana
Authors: Adamson M. L. , Noble S.
Published: June 2009

The pinworm (Oxyurida: Nematoda) guild in a laboratory colony of Periplaneta americana was investigated to answer the following questions. (1) Is guild structure stable with time? (2) Is there evidence of interaction among the species? (3) Is there evidence for niche diversification with respect to spatial distribution or developmental stage of host? Four species were found: Thelastoma periplaneticola, Thelastoma bulhoesi, Hammerschmidtiella diesingi and Leidynema appendiculatum; females of the first two could not be distinguished and they were lumped and referred to as Thelastoma sp.; 328 mid-instar hosts were dissected between September 1987 and February 1990, and the number of adult females of each pinworm species was recorded to investigate changes in guild structure through time. Seventy-five percent of hosts had Thelastoma sp., 62% had H. diesingi and 40% had L. appendiculatum; mean intensities were 6.5 (Thelastoma), 2.9 (H. diesingi) and 1.9 (L. appendiculatum). Relative numbers were stable with time and intensities of the species were similar whether they occurred alone in the host or in conjunction with other species. Thelastoma sp. and L. appendiculatum occurred together less often than expected and their numbers in individual hosts were negatively correlated. Both species occurred alone more often than expected. Surprisingly, H. diesingi and L. appendiculatum occurred together more often than expected. Intestines of 44 roaches were frozen in liquid nitrogen and divided into 5 equal sections to study longitudinal distributions of the species in the gut. Most L. appendiculatum and H. diesingi were found in the first, whereas most Thelastoma sp. occurred in the second segment. However, Thelastoma sp. dominated all segments of the gut. Worms were counted in 192 hosts belonging to 4 categories (early instar, late instar, adult male and adult female). Single species infections were more common in early instar hosts but there was no evidence that different species preferred different host stages. Modal distributions in male L. appendiculatum and T. bulhoesi suggest that these species may exhibit intraspecific interference competition similar to that observed in other pinworms. Such effects may be more important than interspecific effects in maintaining guild stability.
Moderate to heavy infections ofTrichuris trichiuraaffect cognitive function in Jamaican school children
Authors: Nokes C. , Grantham-McGregor S. M. , Sawyer A. W. , Cooper E. S. , Robinson B. A. , Bundy D. A. P.
Published: June 2009

A double-blind placebo trial was conducted to determine the effect of moderate to high loads ofTrichuris trichiura(whipworm) infection on the cognitive functions of 159 school children (age 9–12 years) in Jamaica. Infected children were randomly assigned to Treatment or Placebo groups. A third group of randomly selected uninfected children were assigned to a Control for comparative purposes. The improvement in cognitive function was evaluated using a stepwise multiple linear regression, designed to control for any confounding variables. The expulsion of worms led to a significant improvement in tests of auditory short-term memory (P< 0.02;P< 0.01), and a highly significant improvement in the scanning and retrieval of long-term memory (P< 0.001). After 9 weeks, treated children were no longer significantly different from an uninfected Control group in these three tests of cognitive function. The removal ofT. trichiurawas more important thanAscaris lumbricoidesin determining this improvement. The results suggest that whipworm infection has an adverse effect on certain cognitive functions which is reversible by therapy.
In vitro development of hydatid cysts from posterior bladders and ruptured brood capsules of equine Echinococcus granulosus
Authors: Rogan M. T. , Richards K. Sylvia
Published: June 2009

A variety of morphological forms developed during monophasic culture of ruptured brood capsules of equine Echinococcus granulosus. Attached to some protoscoleces were small posterior bladders, with a surface ultrastructure of truncated microtriches, and these never developed a laminated layer. In contrast, small free vesicles of similar size and ultrastructure, but devoid of an attached protoscolex, produced a layer by 20–30 days. The surface ultrastructure of both these forms is similar to that of the protoscolex attachment stalk and the brood capsule lining, and posterior bladders and small free vesicles are considered to be derived from portions of the stalk±part of the brood capsule lining retained at protoscolex release. Also present were large vesicles interpreted from their size and surface anatomy as ruptured, everted brood capsules. When devoid of attached protosoleces these formed cysts each with a laminated layer, whereas similar vesicles with several attached protoscoleces did not develop a layer, or only very occasionally after 70 or more days. In contrast, a few large vesicles with a single attached protoscolex produced a laminated layer. The possibility that protoscolex attachment to stalk remnants or brood capsules inhibits the cystic development of these structures is discussed.
N-acetylation of biogenic amines in Ascaridia galli
Authors: Isaac R. E. , Eaves L. , Muimo R. , Lamango N.
Published: June 2009

The metabolism of 5-hydroxytryptamine (5-HT), octopamine (OA) and dopamine (DA) by adult male Ascaridia galli was investigated by incubating worms cut into 5 mm lengths with radio-isotope labelled amine. [14C]5-hydroxytryptamine and [14C]octopamine were taken up by the tissues and were metabolized to apolar products that co-chromatographed using both high-performance liquid chromatography and thin-layer chromatography with N-acetyl 5-hydroxytryptamine (NA5-HT) and N-acetyloctopamine (NAOA), respectively. N-acetylation was by far the most important reaction detected under these experimental conditions. A brief incubation of cut worms with [3H]dopamine resulted in the formation of a radio-isotope labelled metabolite that co-chromatographed with N-acetyldopamine (NADA) on reversed-phase high-performance liquid chromatography. The N-acetyltransferase activity towards 5-hydroxytryptamine and octopamine was detected in crude homogenates of male worms only when the co-substrate, acetyl CoA, was added to the reaction mixture. This enzyme activity appeared to be mainly localized in a 40 000 g supernatant fraction. The failure of previous studies to detect N-acetylation of biogenic amines in tissue homogenates of nematodes may have been due to the low levels of acetyl CoA present in these enzyme preparations.
Immunological characterization of cytoskeletal proteins associated with the basal body, axoneme and flagellum attachment zone ofTrypanosoma brucei
Authors: Woodward R. , Carden M. J. , Gull K.
Published: June 2009

The monoclonal antibody BS7, raised to bovine sperm flagellum cytoskeletal antigens in a previous study, is here reported to detect flagellum-associated structures inTrypanosoma bruceiandCrithidia fasciculata. Immunoblotting showed that BS7 cross-reacts with several cytoskeletalT. bruceiproteins but phosphatase treatment did not diminish this complex immunoblot reactivity. To characterize further the cross-reactive proteins recognized inT. brucei-cytoskeletons by BS7 each was excised from preparative gels and used as an immunogen for antiserum production. Two proteins, with apparent sizes around 43 and 47 kDa, produced antisera shown to be monospecific by immunoblotting totalT. bruceiflagellum preparations. Each of these detected the basal body-associated immunofluorescence inT. brucei. Identification of the smaller, 43 kDa, component as a basal body-associated product was supported by the behaviour of a second monoclonal antibody, BBA4, which was also shown to detect theT. bruceibasal body complex by immunofluorescence and immunoblots the 43 kDa polypeptide. These observations reveal new components of the trypanosome cytoskeleton. Also, they provide a further example of an immunological approach for identification of interesting, rare components of theT. bruceicytoskeleton starting from a complex mixture of proteins.
Richness and diversity of macroparasite communities in tropical eels Anguilla reinhardtii in Queensland, Australia
Authors: Kennedy C. R.
Published: June 2009

The prediction that richness and diversity of helminth communities would be greater in tropical fish was tested by analysing total and intestinal helminth communities in samples of Anguilla reinhardtii taken from 10 localities in tropical and semi-tropical freshwaters in Queensland, Australia. Comparison of findings with those from A. anguilla in the UK revealed that regional species richness was higher in Queensland and that helminth communities harboured a suite of common species, virtually all eel specialists, that were responsible for the observed higher levels of similarity between component communities. All measures of community richness and diversity adopted indicated that the poorest helminth communities in A. reinhardtii were comparable with the richest ones reported from the northern temperate A. anguilla. The richest communities in A. reinhardtii were more diverse than those reported from any other species of fish, whether marine or freshwater, to date, and were comparable with the communities found in some species of aquatic birds. Both tropical conditions and age and endemism of the host, i.e. the time hypothesis, were considered as explanations for this richness but neither could be favoured. A cautious approach to generalizations based on data from temperate regions only is advocated, and the need for more studies on tropical parasite communities is strongly emphasized.
Ex vivoevidence for PGE2and LTB4involvement in cutaneous leishmaniasis: relation with infection status and cytokine production
Authors: Milano S. , Arcoleo F. , Dieli M. , D'agostino R. , De Nucci G. , D'agostino P. , Cillari E.
Published: June 2009

Ex vivoculture of spleen cells from BALB/c mice infected with 2 × 106Leishmania major(L.major) promastigotes were cultured with ConcanavalinA (ConA) or leishmanial antigen (L. Ag) and tested for prostaglandin E2(PGE2) and for leukotriene B4(LTB4), in order to study their involvement in the evolution of cutaneous leishmaniasis and the connexion with lymphokine-mediated responses. The data were compared with those obtained in BALB/c mice protected againstL. majorby sublethal irradiation (550 rad; cured mice). In the unprotected BALB/c mice the levels of PGE2that were responsible for the depression of interferon-γ (IFN-γ) and tumour necrosis factor-α (TNFα) Th1-associated cytokines and for the relative increase in the interleukin-4 (IL-4) became higher and higher as the lesion progressed. On the contrary, the cured mice produced levels of PGE2similar to normal uninfected controls, high levels of TNFα and IFN-γ and low levels of IL-4. Elevated levels of LTB4were detected in the early stage of infection in the unprotected mice compared to cured ones, a sign of more intense inflammation and a stimulus for the recruitment of inflammatory cells. The observation that exogenous LTB4was able to enhance in vitro both Th1cytokines in cured mice and Th2cytokines in unprotected ones suggests that LTB4could act in the recruitment of the T cells already committed to Th1or Th2phenotype.
Mice infected with the larvae ofTaenia crassicepsexhibit a Th2-like immune response with concomitant anergy and downregulation of Th1-associated phenomena
Authors: Villa O. F. , Kuhn R. E.
Published: June 2009

Infection of intermediate hosts with eggs of taeniid parasites results in a larval infestation known as cysticercosis. A number of studies have indicated that cysticercosis is associated with immunosuppression, although little is known about the mechanisms involved. In the present study, mice infected with the larvae ofTaenia crassicepswere found to exhibit a pronounced anergy, which preferentially affected T-cells located anatomically close to the parasite. This anergy was linked to late events in the T cell activation pathway; that is, stimulation through the T cell receptor(TCR)/CD complex by Concanavalin-A, or plate-bound monoclonal antibodies (mAb) to TCRαβ or CD3ε, or combinations of phorbol ester and ionomycin (all of which can bypass early membrane-related events), failed to fully activate T lymphocytes. The relative proximity of T cells to the parasite was directly related to upregulation of IL-4 and downregulation of IL-2 production. In addition, the profiles of parasite-specific Abs showed an exclusive increase of serum IgG1 during infection. Taken together, the data suggest that infection of mice with larvae ofT. crassicepsalters the balance of CD4+Th cells by upregulating Th2 and downregulating Th1 cells located in close proximity to the parasite.
Hypoxanthine: a low molecular weight factor essential for growth of erythrocyticPlasmodium falciparumin a serum-free medium
Authors: Asahi H. , Kanazawa T. , Kajihara Y. , Takahashi K. , Takahashi T.
Published: June 2009

A low molecular weight factor in a basal medium essential for erythrocyticPlasmodium falciparumdevelopment in a serum-free medium using a cell growth-promoting factor derived from adult bovine serum was detected. The factor was hypoxanthine. The optimal hypoxanthine concentration for parasite growth was between 15 and 120 μM. The contribution of hypoxanthine to increased parasite growth was clearly evident in cultures on day 4. Among various low molecular weight supplements tested, adenine, adenosine, AMP, ATP, cyclic AMP, guanine, guanosine, inosine, inosine mono-phosphate, xanthine, NAD, NADH, NADP, NADPH and deoxyguanosine triphosphate showed a similar effect to that of hypoxanthine in the serum-free culture system. On the other hand, the addition of uric acid, FAD, thymidine, uridine, orotic acid, deoxythymidine triphosphate, deoxycytidine triphosphate, deoxyadenosine triphosphate, ribose-1-phosphate, or ethanolamine was not beneficial to the parasite growth. The results presented here will not only be of practical value, but will provide important information about the developmental requirements of the parasite.
Predisposition of mice to Heligmosomoides polygyrus and Aspiculuris tetraptera (Nematoda)
Authors: Scott Marilyn E.
Published: June 2009

The purpose of this study was to determine whether predisposition to Heligmosomoides polygyrus and Aspiculuris tetraptera (Nematoda) exists within a naturally infected population of mice. A breeding mouse population was housed in a spacious arena in which endemic infections of H. polygyrus and A. tetraptera were present. H. polygyrus were over-dispersed in the mouse population. Prevalence reached 100% by the age of 3 weeks; intensity of infection increased to a peak in the 10 to 15-week-old mice, and remained high throughout life. A group of 73 mice was treated with pyrantel pamoate, and the expelled worms were counted. Mice were returned to the arena. Daily egg production was monitored 4, 8, 12 and 14 weeks after treatment. Mice were then killed and numbers of H. polygyrus and A. tetraptera were counted. Significant positive correlations were detected between numbers of H. polygyrus at first treatment and at necropsy, indicating the existence of predisposition. Similar results were obtained for A. tetraptera. Correlations improved when data were analysed by age class of mice. Analyses based on egg-count data during reinfection did not support the hypothesis of predisposition, however. A. tetraptera and H. polygyrus burdens were significantly correlated only in 3 to 4-week-old mice at the time of the treatment.
Caecal threadworms Trichostrongylus tenuis in red grouse Lagopus lagopus scoticus: effects of weather and host density upon estimated worm burdens
Authors: Moss R. , Watson A. , Trenholm I. B. , Parr R.
Published: June 2009

Trichostrongylus tenuis eggs were counted in faeces from individually marked wild red grouse for 8 years. Egg counts varied seasonally and annually. In some years, a sudden increase in mid-April was consistent with delayed maturation of larvae which had overwintered in the birds in a hypobiotic state. A more gradual increase in summer was probably due to uninterrupted maturation of larvae ingested then. Despite 30-fold year-to-year variation in mean egg counts, relative differences in egg counts among known individuals within years tended to persist across years. Rainfall in previous summers explained much of the year-to-year variation in egg counts, probably because parasite recruitment was greatest during wet summers. Grouse density was only weakly related to worm egg counts. The data were not consistent with the hypothesis that the cyclic-type population fluctuation in red grouse numbers observed at the time of this study was caused by the parasites.
Hatching, survival, activity and penetration efficiency of second-stage larvae of Anguillicola crassus (Nematoda)
Authors: Thomas K. , Ollevier F.
Published: June 2009

Hatching of eggs of Anguillicola crassus was studied at temperatures between 5 and 30°C. Hatching occurred between 10 and 30°C and the incubation time was inversely related to temperature. Survival, spontaneous and excitatory rate of activity of 2nd-stage larvae of A. crassus were also affected by temperature. The percentage of larvae eaten by Paracyclops fimbriatus was not always influenced by the activity of the larvae. Penetration efficiency into the haemocoel of the intermediate host was highest for freshly hatched larvae and declined gradually with age. Completely non-active larvae were still able to penetrate, although penetration efficiency was lower.
The distribution of developing Brugia pahangi and Brugia malayi larvae within the dorsal longitudinal flight muscles of Aedes aegypti and Mansonia uniformis
Authors: Beckett Evelyn B.
Published: June 2009

1. The distribution of larvae within the dorsal longitudinal muscle fibre groups of A. aegypti infected with subperiodic B. malayi or B. pahangi and of M. uniformis infected with the former parasite was studied with the aid of serial sections.

2. In all experiments the top bundles of fibres contained fewer parasites than either the middle or lowest bundles, but whereas most parasites were concentrated in the middle bundles in A. aegypti there was no significant difference in M. uniformis between the bottom and middle fibre bundles. The lowermost fibre was not the most heavily parasitized of the dorsal longitudinal group.

3. Nothing is known of what determines whether or not a particular fibre becomes parasitized, but it was concluded that the distance between the fibre and the gut (from which the parasites emerge to travel to the muscle) is not the principal factor.

I am very much indebted to Mr Cheong Weng Hooi and his colleagues for collecting and processing mosquitoes in Kuala Lumpur and to Mrs J. Oliver who finished the processing in Liverpool. I am grateful also to Dr W. W. Macdonald for his advice and help in all stages of this work and to Miss M. A. Johnson who assisted with the care of the A. aegypti colony and prepared the diagrams for this paper.
Ascaris, people and pigs in a rural community of Jiangxi Province, China
Authors: Weidong Peng , Xianmin Zhou , Xiaomin Cui , Crompton D. W. T. , Whitehead R. R. , Jiangqin Xiong , Haigeng Wu , Jiyuan Peng , Yang Yang , Weixing Wu , Kaiwu Xu , Yongxing Yan
Published: June 2009

A longitudinal investigation on natural populations of Ascaris in humans and pigs and an investigation of soil contamination with Ascaris eggs were carried out from June 1993 to June 1994 in 2 villages, Manhu area, Xinjian County, Jiangxi Province, China. Results from these studies indicate that although human ascariasis is endemic there is significant fluctuation in both prevalence and the mean number of eggs/g faeces (epg) of the communities. Fluctuation of age-stratified prevalence and mean epg was detected in children but not in most adult groups. Most cases of human ascariasis were judged to involve low intensities of infection and a typical overdispersion distribution pattern was observed through the year. It was estimated that during the year, nearly half of the eggs discharged in the environment came from infections in children aged between 2 and 15 years which accounted for about 30% of the total population. Soil in and around houses and in vegetable gardens was found to be contaminated by Ascaris eggs and this situation remained relatively stable throughout the year. Monthly developmental rate of Ascaris eggs in soil was detected and the results suggest that the fluctuation in prevalence observed during the year should be directly attributed to the effect of seasonality of egg development. Features of Ascaris infection in pigs were found to be similar to those in humans except for a lower mean intensity of infection. The possibility of cross-infection of Ascaris between human and pig hosts is discussed.
Serotonin and acetylcholine: further analysis of praziquantel-induced contraction of magnesium-paralysed Schistosoma mansoni
Authors: Blair K. L. , Bennett J. L. , Pax R. A.
Published: June 2009

The nature of stimulus-induced flaccid paralysis produced in Mg2+-paralysed Schistosoma mansoni was investigated. Serotonin induced a dose-dependent, heterologous flaccid paralysis with an IC50 of 600 nm. This flaccid paralysis was a function of the extracellular Mg2+:Ca2+ ratio and was reversible. Tonic contractions produced by phorbol-12,13- dibutyrate or 60 mM K+ were reversed by the application of serotonin and flaccid paralysis was induced. These actions of serotonin were mimicked by forskolin and synergized by IBMX but the potassium channel blocker, 3,4-DAP, did not produce flaccid paralysis. When Mg2+-paralysed parasites were stimulated with 3,4-DAP, IBMX produced a dose- dependent flaccid paralysis with an IC50 of 11 μm. Membrane permeable analogues of cAMP and cGMP did not synergize with IBMX. Cholinergic agonists, but not other inhibitory substances, prevented the serotonin- and forskolin-induced and the IBMX-synergized flaccid paralysis but not that produced by praziquantel. The possible interactions of these agents with the muscle are discussed.
A note on the taxonomy of an undescribed insect parasitic nematode in the genus Neoaplectana
Authors: Schmiege Donald C.
Published: June 2009

The genus Neoaplectana now contains eleven species of nematodes. All are associated with insects. A brief review of the history of the genus is given. An undescribed species referred to as DD-136 is compared with one other species in the genus Neoaplectana. It is very similar to the description given for N. carpocapsae Weiser, and it is concluded that it is probably this species.
Two new species of the genus Haematoloechus (Digenea: Plagiorchiidae) from Rana occipitalis (Gunther) in Ghana
Authors: Rees Gwendolen
Published: June 2009

Haematoloechus (Haematoloechus) exoterorchis sp.nov. and H. (H.) micrurus sp.nov. have been found in the lungs of Rana occipitalis (Gunther) in South Ghana.

62·5% of the frogs were infested with one or other or with both species.

The two species occupy different positions in the lungs of the host. H. (H.) exoterorchis is cylindrical and is wedged, anterior end foremost, into the alveoli. H. (H.) micrurus is flattened and remains free in the central lumen of the lung.

In the former case the wall of the alveolus, containing the worm, becomes stretched to a thin membrane.

The morphology of both species is described with reference to their different habitats.

A brief discussion of the genus is included.

I am most grateful to the University of Ghana and to the staff of the Zoology Department at Legon for the facilities which they placed at my disposal and without which the work could not have been done.
External stimuli and intracellular signalling in the modification of the nematode surface during transition to the mammalian host environment
Authors: Proudfoot L. , Kusel J. R. , Smith H. V. , Kennedy M. W.
Published: June 2009

Previous work has shown that the surface of infective larvae of parasitic nematodes will not bind the fluorescent lipid analogue 5-N(octadecanoyl)aminofluorescein (AF18) until after exposure of the parasite to mammalian tissue-culture conditions. In this study, culture media which are permissive or non-permissive for the acquisition of lipophilicity for AF18 were altered in order to examine possible stimuli involved. This showed that external alkaline pH and high sodium ion concentration were highly stimulatory. The internal signalling pathways which may be involved in the surface alteration were then examined using agents which are known to affect intracellular signalling in mammalian cells. The results indicated that elevation of cGMP levels was stimulatory whereas inhibition of a putative Na+/H+ antiporter or calcium mobilization was inhibitory, and it is argued that high intracellular levels of cAMP may be inhibitory. Whilst the precise effects of the agents used on nematode cells remain to be established, these results provide a framework for the examination of the processes involved in the modification of the nematode surface which takes place immediately after the infection event.
The rapid development of the glucose transport system in the excysted metacestode ofHymenolepis diminuta
Authors: Rosen R. , San M. L. , Denton M. E. , Wolfe J. M. , Uglem G. L.
Published: June 2009

Temporal changes in glucose transport capacity in excysted scoleces ofHymenolepis diminutawere examined. Assays involved incubation for 1 min in [3H]glucose after pre-incubation for 1 min to 8 h in saline. There were two abrupt increases in uptake velocity, a relatively small one between 15 and 75 min, and a large one between 5 and 6 h, during which theVmaxincreased from 0·36 to 2·49 nmol/25 larvae/h. The second increase was unaffected when the pre-incubation saline contained 5 mM glucose, but it was completely blocked when the excysted larvae were pre-incubated in Ca2+-free saline. Abrupt glucose transport changes did not occur in intact cysticercoids or in scoleces when the substrate was [3H]leucine or [3H]uracil. Arrhenius plots (logVversus 1/temperature, 10–42 °C) were linear for intact cysticercoids, but were biphasic for both scoleces and adults with discontinuities at 20 ± 1 °C. Thus, ‘activation’ of the excysted scolex seemed to involve a specific, Ca2+-dependent increase in number of glucose transporters functioning in the worm surface. The Arrhenius plots indicated that development in the final host does not involve a major change in lipid composition of the parasite's membranes.
Two species of Peritrichous Ciliata epibiotic on parasitic Crustacea from Lake Albert, Uganda
Authors: Green J.
Published: June 2009

Rhabdostyla elongata sp.nov. is described and figured. This peritrich was found as an epibiont on Lernaea barnimiana, a copepod parasitic on the Nile Perch, Lates niloticus in Lake Albert.

Epistylis articulata Fromentel is recorded as an epibiont of Dolops and Argulus, which parasitize a wide range of fish in Lake Albert.

My thanks are due to Mr M. J. Holden who identified the fish as they were removed from the nets, and to Dr G. Fryer, who identified Lernaea barnimiana and has helped with the literature. I am also grateful for a grant from the Leverhulme Trust which made possible the collection of this material.
The structure and histochemistry of the cyst wall of the metacercaria ofFasciola hepaticaL.
Authors: Dixon K. E.
Published: June 2009

The cyst wall which encloses the metacercaria ofFasciola hepaticaconsists of four major layers, one of which is further divisible into three sublayers. These layers are numbered I to IV, the first being the external layer. Layers I and II form the outer cyst which may be separated from the inner cyst formed from layers III and IV.

Layer I, the thick incomplete external layer, covers the metacercaria dorsally and laterally. It is composed of tanned protein.

Layer II is a thin fibrous layer closely adherent to the inner surface of layer I and is composed of mucoprotein and acid mucopolysaccharide.

Layer III is made up of three separate sublayers, the relative widths of which vary in different regions of the cyst. In general IIIaconsists of mucoprotein, IIIbof acid mucopolysaccharide and IIIcof neutral mucopolysaccharide.

In the dorsal and lateral regions, layer IV appears to be formed of lamellae held in a protein–lipid matrix. The lamellae are composed of protein stabilized by disulphide linkages.

In the ventral region of layer IV there is a thickened mucopolysaccharide area, the ventral plug, through which the metacercaria excysts.

The relative importance of these resistant layers in providing protection against desiccation, toxic substances and attack by other organisms is discussed.

This work was carried out during the tenure of a Commonwealth Post Graduate Scholarship. The author is grateful to Professor J. D. Smyth and Dr J. A. Clegg for advice and encouragement during the course of this work and in preparation of the manuscript.
The growth of some species of Eimeria in avian embryos
Authors: Long P. L.
Published: June 2009

Four species of Eimeria from fowls were able to develop in chicken embryos following the inoculation of sporozoites. Three species (E. brunetti, E. mivati and E. tenella) were able to complete the whole of their endogenous cycle in embryos. E. necatrix developed to late schizogony, E. acervulina and E. maxima did not develop.

The life-cycles appeared to be delayed, and in the case of E. tenella embryo mortality was associated with heavy parasitism of the chorioallantoic membranes. Oocysts recovered from urate deposits in the allantoic cavity sporulated normally and induced infections in chickens.

Attempts to infect turkey and quail embryos with E. tenella or chicken and turkey embryos with E. stiedae were unsuccessful.

The implications of the findings are discussed.

I wish to thank Dr C. Horton-Smith for his encouragement and guidance with this work; Dr M. E. Rose for help in the preparation of the manuscript and Mr B. J. Millard for careful technical assistance.
The host-parasite interface of Cyathocotyle bushiensis Khan, 1962 (Trematoda: Strigeoidea)
Authors: Erasmus David A.
Published: June 2009

A combination of histochemical and electron microscope techniques have demonstrated, in Cyathocotyle bushiensis, alkaline phosphatase activity in the matrix of the tegument, in the distal and basal plasma membranes of the tegument, in the wall of the ducts extending from the adhesive organ gland cells and in the wall of the adhesive organ microvilli. Acid phosphatase activity was much stronger and was present in the tegument matrix and in the granular component of the secretion from the adhesive organ gland cells. Strong acid phosphatase activity was also present in the cisternae of the endoplasmic reticulum of the adhesive organ gland cells.

I am greatly indebted to Professor Brough for the excellent facilities available within this department. I also wish to thank Professor J. Sinclair (Department of Mining) for electron microscope facilities extended to me in the early stages of this investigation, and to Mr W. Henderson, Mr T. Davies and Miss M. Williams for their invaluable assistance. The purchase of the Huxley ultramicrotome, coating unit and an AEI EM 6 electron microscope was made possible by a grant from the Science Research Council.
The synonymy of Ixodes festai Rondelli 1926
Authors: Arthur Don R.
Published: June 2009

Ixodes festai was originally described from two Libyan and Tunisian female specimens from two different avian hosts by Dr M. Rondelli in 1926. Subsequently the female was re-described and the male and immature stages described from specimens collected in the Nefifik forest near Casablanca (Arthur, 1957a, 1958). Details of the life history were reported by Blanc & Bruneau (1958) and by Arthur (1958) from information furnished by Bruneau. More recently Morel (1959) has reported the occurrence of this species in France, but previously Gil Collado (1936, 1948) described it as a Spanish species under the name of Ixodes ventalloi.
Gorgoderina alobata sp.nov. (Trematoda: Gorgoderidae) from the toad Bombina variegata
Authors: Lees E. , Mitchell J. B.
Published: June 2009

A bladder fluke from the toad Bombina variegata is described and erected as a new species under the name of Gorgoderina alobata sp.nov. A comparison is made between this trematode and G. carli Baer, 1930, from India. It is also compared with the other two previously described European species, G. vitelliloba (Olsson, 1876) and G. skrjabini Pigulevsky, 1953.
Immunity to coccidiosis: protective effect of transferred serum in Eimeria maxima infections
Authors: Rose M. Elaine
Published: June 2009

Serum taken between 2 and 3 weeks after infection of the donors with E. maxima conferred a considerable degree of protection against infection with the homologous organism when injected daily into young recipients. Different pools of such sera had differing activities, but the majority gave protection of 50% or more whereas a few were inactive.

The degree of protection obtained was dose-dependent, varying directly with the volume of serum injected and inversely with the size of the challenge oocyst inoculum.

A course of injections started early in the life-cycle had a greater effect than those started in mid- or late cycle even when comparatively large volumes of serum were given.

Protection was species specific; serum obtained from birds infected with E. maxima did not protect against E. praecox or E. acervulina.

The assistance of Mrs Patricia Hesketh is gratefully acknowledged, as is the help of other members of the staff of the Parasitology Department. Mr P. Townsend, Senior Poultry Attendant, supervised the cleaning and sterilization of cages and the collection of faecal samples.
Studies on gut ultrastructure and digestive physiology in Cyathostoma lari (Nematoda: Strongylida)
Authors: Colam J. Barry
Published: June 2009

Histological, histochemical and ultrastructural methods have been used to study the gut structure and digestive physiology in the parasitic nematode Cyathostomalari E. Banchard, 1849. The nematode is parasitic in the orbito-nasal sinuses of its host and feeds exclusively upon blood.

Three gland cells are present in the oesophagus, one in each sector. The two subventral gland ducts open into the lumen of the oesophagus at the level of the nerve ring, and the dorsal gland duct into the base of the buccal capsule. It is suggested that the latter gland may produce an anticoagulin, histolytic and/or haemolytic secretions, histochemically-inactive in situ. The intestine is syncytial, with no differentiation into secretory components, and its distal surface is provided with a prominent brush border of long microvilli.

A non-specific esterase, thought to originate in the oesophageal gland secretions, causes haemolysis of ingested erythrocytes. The major part of haemoglobin digestion is extracellular, partly by a process of contact digestion on the microvilli, initiated by the esterase, and the protein is then further broken down by an exopeptidase of the ‘leucine aminopeptidase’ type, and the products absorbed into the gastrodermis possibly with the aid of an acid phosphatase present on or in the microvilli. An insoluble iron-containing compound, which is not haematin, results from breakdown of the prosthetic group. A smaller proportion of haemoglobin is taken up by the gastrodermis and digested intracellularly by the action of lysosomal hydrolases. An endopeptidase and an acid phosphatase are present in the gastrodermis, possibly in sacs of GER which are suggested to be primary lysosomes and which fuse with the endocytosed heterophagosomes. The insoluble pigment haematin results from digestion within the heterolysosomes, and this gives rise to the iron-containing gastrodermal pigment granules. The products of extracellular digestion are absorbed by the gastrodermis where they are synthetized into lipid by a lipase, which probably resides in whorls of GER.

This investigation was supported in part by Research Grant AI 06295 of the United States Public Health Service. The final manuscript was prepared during the tenure of a Postdoctoral Fellowship from the British Egg Marketing Board. I wish to extend my gratitude to Dr J. B. Jennings for advice and encouragement throughout this work.
The dynamics of the host–parasite relationship
Authors: Dineen J. K. , Wagland B. M.
Published: June 2009

The response of sheep given six sensitizing infections each of 3000 infective larvae of H. contortus at fortnightly intervals to a challenge infection of 3000 infective larvae has been studied. While a large proportion of the challenge infection (ca. 3000 parasites) persisted to termination of the experiment on day 141 in sheep (group 3) in which the challenge was superimposed upon the sensitizing infections, only a mean of 437 worms, including both 4th-stage larvae and adults, was recorded at this time in another group (group 5) in which the sensitizing infections were terminated by anthelmintic treatment on day 90, i.e. 8 days before challenge. The proportion of the total worm burdens of the challenge infections arrested at the 4th larval stage was increased for both groups (25% for group 3 and 18% for group 5) by comparison with unsensitized control groups (4% for group 6 and 2% for group 7).

As the effect of immunological control was expressed more vigorously in the group (group 5) in which the sensitizing infections were terminated before challenge it seems likely that recovery of immunological competence occurred in these animals following removal of the sensitizing infections. This conclusion suggests that, owing to the persistence of the sensitizing infections and therefore exposure of the immune mechanism to continuous antigenic insult, the animals which received the superimposed challenge infection had entered a phase of immunological exhaustion during the challenge period.
Population studies on the infective stage of some nematode parasites of sheep I. The frequency distribution of strongyloid infective larvae in random samples of pasture
Authors: Donald A. D.
Published: June 2009

Observations have been made on the frequency distribution of strongyloid infective larvae in random samples of pasture herbage collected on four occasions from a quarter-acre field grazed by five sheep carrying mixed strongyloid infections. The distribution of numbers of infective larvae of the genera Haemonchus, Trichostrongylus and Cooperia in each of the samples has been examined. The variance of each series was found to be substantially larger than its mean and, hence, the distributions were all highly overdispersed statistically. Of a number of frequency distribution models, the ‘truncated lognormal’ was found to provide the best empirical fit to the sample distributions.

The implications of these findings for determining the significance of the difference between two random sample estimates of the abundance of infective larvae in pasture, have been discussed. It has been shown that, because of the limit imposed by technical considerations on the maximum size of herbage samples, and because the distribution of infective larvae in pasture departs markedly from a random one, only quite large differences between the means of two random sample estimates are likely to be significant. However, because the numbers of infective larvae of the different strongyloid genera are highly correlated within sample units, considerably smaller differences between the means for different genera, within the same sample, can be detected as significant.

From a consideration of the complexity of the biological components generating populations of infective larvae on pasture, it has been concluded that simple frequency distribution models can contribute little towards an improved understanding of the population dynamics of strongyloid infective larvae in pastures grazed by sheep.