bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of cell types in the parenchyma ofSchistosoma mansoni
Authors: Reissig Magdalena
Published: June 2009

A study has been made of the parenchyma of adult maleSchistosoma mansoniby electron microscopy. Four different cell types have been characterized: one corresponding to cell bodies of the integument, two to muscle cells and another one to nerve cells with a possible neurosecretory function. The cytoplasm of the integument cell bodies is characterized by rod-shaped and round membrane-bound cytoplasmic bodies with a dense core, measuring 1200 to 2000 Å, similar to those found in the integument. One type of muscle cell has a large, clear nucleus, characteristic cytoplasmic vacuoles measuring up to 1 μm with a finely granular content and numerous free ribosomes. The other type of muscle cell is much smaller, with clumped nuclear chromatin and scanty perinuclear cytoplasm. Both types of cells give rise to muscle fibres which are morphologically distinct from the perinuclear cytoplasm. The nerve cells contain electron-dense, membrane-bound vesicles-ranging in size from 1000 to 3000 Å, similar to those found in nerve axons.

Appreciable extracellular matrix has only been found under the integument and surrounding the processes of the integument cell bodies. This observation and the fact that silver methenamine after periodic oxidation stains intensely both the extracellular substance and the rod-shaped and round cytoplasmic bodies of the integument cells, suggests that these integument cells may be involve the production of extracellular matrix.

This investigation was supported by grant AI 07806 from the U.S.P.H.S.

The technical assistance of Mrs Lucille Jeffries and the photographic assistance of Mr William Douglas are acknowledged. This investigation was supported by the United States–Japan Cooperative Medical Science Program administered by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, Department of Health, Education and Welfare.
Studies on ascaridoid nematodes in pythons: the life history and development of Polydelphis anoura in Australian pythons
Authors: Sprent J. F. A.
Published: June 2009

P. anoura was found in 55 % of pythons (M. spilotes variegatus) in Brisbane. Eggs contained first stage larvae after 8 days development; the first moult was completed by 10 days; the eggs were infective after 14 days. After ingestion by tadpoles, the larvae hatched from the eggs and migrated into the tissues but did not show any growth. In mice and rats the larvae migrated mainly to the liver, lungs and intestinal wall, where growth occurred to a length of 5–6 mm by 6 months after infection. The second moult was not observed, but the larvae were infective to pythons after 39–42 days development. From their structure it was assumed that after this time the larvae in mouse tissues were third-stage larvae.

Various species of Australian python, Morelia spilotes, Liasis amethistinus, L. fuscus and L. childreni, were experimentally infected with larvae of Polydelphis anoura by feeding nodules from the wall of the small intestine of experimentally infected mice and rats. The third moult occurred in the stomach within 14 days, moulting larvae at this stage measured between 3.5 and 7.0 mm long. Fourth-stage larvae occurred in all python species, the smallest being 4 mm. Growth and development of the fourth stage occurred at first in the oesophagus and stomach. Up to 2 months after infection, larvae had not grown more than 12 mm, yet they were clearly differentiated into males and females. In mouse-infected M. spilotes growth to 20 mm was reached by 154 days, but it was not until 183 days that adults were observed.

Comparison with adult specimens from P. reticulatus from Malaya confirmed the previous observation that Australian male specimens have relatively shorter spicules than male specimens from other geographical regions. Growth, development and location of larvae in mice, experimentally infected with eggs from Australian and Malayan specimens, appeared to be the same.
An unusual form of fertilization in the malaria parasite of the Himalayan flying squirrel
Authors: Dasgupta B. , Chatterjee Amal
Published: June 2009

Fertilization phenomena has been observed in the malaria parasite of the Himalayan Flying Squirrel with blood showing heavy infection. The blood was obtained on the slide, put in the moist chamber, dried and stained. Two types of microgametes could be distinguished. One of these two types were found in various stages of the process of fertilization. More than one microgamete were often found to take part in fertilizing a single macrogamete. This is the first recorded case of polyspermy in malaria parasites.

Thanks are due to Mr Nandalal Pau for his help in preparing the Plate incorporated in this paper.

This investigation received financial support from the World Health Organization.
Physiological and pharmacological properties of muscle cells isolated from the flatwormBdelloura candida(Tricladia)
Authors: Blair K. L. , Anderson P. A. V.
Published: June 2009

A protocol for dissociating single muscle fibres from intact flatworms was developed. Muscle fragments of various sizes were obtained, many with their cell bodies, or myocytons, intact. Many of the fibres were spontaneously contractile, and they and others contracted in response to applications of transmitter candidates, activators of protein kinase C and the anthelmintic praziquantel. The responses were all similar to those evoked in strips of tissue. Voltage clamp recordings from the isolated muscle fibres revealed that they possess an inward Ca2+current and 3 separate K+currents. These results indicate that muscle fibres inBdellourabear receptors for neurotransmitters and that preparations of dispersed muscle fibres can be used for studying the basic physiological and pharmacological properties of platyhelminth muscle.
The development and validation of an age-structured model for the evaluation of disease control strategies for intestinal helminths
Authors: Chan M. S. , Guyatt H. L. , Bundy D. A. P. , Medley G. F.
Published: June 2009

Epidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted treatment programmes. The model was verified using field data from control programmes forAscaris lumbricoidesandTrichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes.
Complete developmental cycle ofLeishmania mexicanain axenic culture
Authors: Bates P. A.
Published: June 2009

A complete developmental sequence ofLeishmania mexicanahas been produced in axenic culture for the first time. This was achieved by manipulation of media, pH and temperature conditions over a period of 16 days. All experiments were initiated with lesion amastigotes that were transformed to multiplicative promastigotes by culture in HOMEM, 10% foetal calf serum, pH 7·5, at 25 °C. Metacyclogenesis was induced by subpassage in Schneider'sDrosophila medium, 20% foetal calf serum, pH 5·5, and the resulting forms transformed to axenically growing amastigotes by subpassage in the same medium and raising the temperature to 32 °C. Parasites from each day were characterized with respect to their general morphology using light microscopy of Giemsa-stained smears, and biochemically by analysis of total protein content, proteinases, nucleases and secretory acid phosphatase. The results demonstrated that the three main stages identified - amastigotes, multiplicative promastigotes and metacyclic promastigotes - each exhibited the expected suite of biochemical properties. Further, the changes in morphology observed as the developmental sequence proceeded from stage to stage were accompanied by appropriate changes in biochemical properties. These results provide both useful biochemical markers and a culture system in which to examine the regulation of differentiation and transformation during theLeishmanialife-cycle.
Genomic and phenotypic diversity of TunisianTheileria annulataisolates
Authors: Miled L. Ben , Dellagi K. , Bernardi G. , Melrose T. R. , Darghouth M. , Bouattour A. , Kinnaird J. , Shiels B. , Tait A. , Brown C. G. D.
Published: June 2009

This study describes polymorphism inTheileria annulata, an intracellular protozoan parasite of bovine leucocytes and red blood cells. Fifty-three different stocks ofT. annulata, isolated from 17 sites (districts) in Tunisia, have been characterized by anti-parasite monoclonal antibody (MAb) reactivity, glucose phosphate isomerase (GPI) isoenzyme electrophoresis, and Southern blotting with two genomic DNA probes. There appears to be considerable diversity amongstT. annulatastocks from Tunisia, no two isolates being identical, even those from animals on the same farm. Two distinct antigenic populations were detected by MAb 7E7. They were defined by negative and positive cells in the indirect fluorescent antibody test. The percentage of positive cells in different isolates ranged between 0 and 100%. The population variation seen by GPI analysis and DNA probes was greater; 7 different GPI phenotypes were identified amongst the stocks studied, while DNA probesT. annulataTunis (TaT) 17 and 21 detected up to 5 different variants. The majority of isolates were shown to contain more than one parasite population, the number of variants per isolate ranging from 1 to 4. No correlation between particular parasite phenotypes or genotypes and their geographical site of isolation was observed. Selection of parasite populationsin vivoandin vitrois also discussed.
Genetic relatedness as a determinant of predisposition to Ascaris lumbricoides and Trichuris trichiura infection
Authors: Chan L. , Bundy D. A. P. , Kan S. P.
Published: June 2009

The present study examines the role of host genetics in predisposition to Ascaris lumbricoides and Trichuris trichiura infection, by comparing the associations between age-standardized infection intensities of parents and their children (genetically related), with age-standardized infection intensities of parents alone (not related), within families previously demonstrated to exhibit familial predisposition. The lack of a consistent trend in infection intensity associations within families, in particular the lack of a stronger association between parents and their children than between unrelated parents, suggests that host genetic factors are not a major determinant of infection status. If there is a genetic basis for predisposition, then the data suggest that the effects of this genetic basis are overwhelmed by other, environmental or behavioural features of the family household.
Characterization of identifiable neurones in the head ganglia of the parasitic nematode Ascaris suum: a comparison with central neurones of Caenorhabditis elegans
Authors: Holden-Dye L. , Walker R. J.
Published: June 2009

Intracellular recordings have been made from neurones in the head ganglia of Ascaris. The neurones had low resting membrane potentials of –21±9 mV (n = 78) and a relatively high input resistance (e.g. 25 MΩ for a 100 μm cell). In all cases the intracellular location of the recording electrode was verified by injection of the fluorescent marker, 5, 6-carboxyfluorescein (CBXF). To ascertain whether or not the low membrane potential was due to impalement damage, the same neurone was recorded from using two microelectrodes. The membrane potential following the first impalement by a 20 MΩ 3 M KCl electrode was –38 mV and following the second impalement by a 80 MΩ CBXF (for subsequent intracellular labelling) electrode was decreased to –34 mV. Input resistance of these cells was estimated using both single and two electrode intracellular recording techniques and in both cases yielded a relatively high value for the size of cell (e.g. 25 MΩ for a 100 μm cell). Neurones labelled by intracellular injection of the fluorescent marker 5, 6-carboxy-fluorescein were morphologically simple and lacked extensive arborizations. The dorsal ganglion is a discrete structure consisting of only 3 neurones. Here we compare the morphological properties of these neurones to those described in the dorsal ganglion of Caenorhabditis elegans. The whole mount preparation of Ascaris ganglia thus provides a useful model to study the functional properties of neurones in nematode central nervous system and presents the possibility to assess central sites of action for anthelmintics.
Fine structure of zoosporulation in Perkinsus atlanticus (Apicomplexa: Perkinsea)
Authors: Azevedo C. , Corral L. , Cachola R.
Published: June 2009

Light and transmission electron microscopy were used to study different stages of Perkinsus atlanticus (Apicomplexa) during induced zoosporulation, with fluid thioglycollate medium and seawater. Cytokinesis and nucleokinesis of different developmental stages were studied every 12 h during the incubation period of 72 h, at which time the zoospores became free. Uninucleated and flagellated zoospores present the apical complex formed by conoid, polar ring, micronemes, rhoptries and subpellicular microtubules observed at different sections. Ultrastructural details were compared with the other two species of the genus Perkinsus.
The prevalence of naturally acquired multiple infections of Wuchereria bancrofti and human malarias in anophelines
Authors: Burkot T. R. , Molineaux L. , Graves P. M. , Paru R. , Battistutta D. , Dagoro H. , Barnes A. , Wirtz R. A. , Garner P.
Published: June 2009

Malaria and filaria infection rates were determined for anopheline mosquitoes collected whilst biting and resting in village houses in Papua New Guinea. The number of anophelines infected with both parasites was greater than expected from the infection rates of each parasite and this difference was significant in resting collections. The excess of multiply infected mosquitoes is probably a result of a vector population composed of individuals with differing numbers of opportunities to become infected. Malaria-positive, Anopheles punctulatus from resting catches had a significantly greater number of Stage 3 Wuchereria bancroftilarvae than malaria-negative mosquitoes. However, multiply infected mosquitoes appear to suffer greater mortality than non-infected or singly infected mosquitoes when the filarial worm reaches the third stage. Any potential increase in transmission resulting from multiple infections is thereby offset by a greater mortality rate in these mosquitoes.
Development of larvalEchinococcus granulosusconfronted with chicken heart tissuein vitro
Authors: Janssen D. , De Rycke P. H. , De Ridder L.
Published: June 2009

Vesiculated protoscoleces (VP) were produced by culturing freshly collected protoscoleces fromEchinococcus granulosushorse liver hydatids in RPMI 1640 monophasic medium at 37°C for 18 days. Half of the VP were used as such, the other half used after killing them by freeze—thawing. Nine-day-old chicken heart fragments (CHF) were cultured in MEM at 37°C for 72 h. Subsequently, CHF were put together with live and dead VP, respectively, for up to 53 days, on a semisolid medium consisting of agar, Ringer's and MEM. Time-dependent histological observations revealed that dead VP were surrounded by CHF cells. Dead VP tissue was eventually internalized and disintegrated in about 1 week. Live VP penetrated into the CHF tissue and further developed into small hydatid cysts, located within the boundaries of the experimental ‘host’ tissue. The amorphous-looking contact region PAP-stained positively only with anti-E. granulosusserum and not with anti-CHF serum; it was considered identical to the normal laminated layer. The invasion of VP in CHF tissue proved to be different from a tumour or a bacterial invasion: it was concluded that the confrontation of VP and CHF had resulted in an ‘in vitrocohabitation’ rather than in an ‘in vitroinfecion’.
Infectivity, antigenicity and host responses to isolates of the genusTrichinella
Authors: Bolas-Fernandez F. , Wakelin D.
Published: June 2009

Comparisons were made of the infectivity and antigenicity of 4Trichinella spiralisisolates (S, D, Y, W), of quite different geographical origins, andT. pseudospiralis(P) in rapid- and slow-responder inbred mice. Infectivity was measured by the Index of Reproductive Capacity (ICR) expressed as the ratio between the number of muscle larvae recovered on day 30 post-infection (p.i.) and the numbers of larvae given at infection. Antigen recognition was measured by the degree of proliferation of mesenteric lymph node cells (MLNC) toin vitrostimulation with crude muscle larvae antigen (CMLA) and by the total antibody responses to CMLA at day 25 p.i. as measured by ELISA. Regarding infectivity the isolates fell into two groups, high infectivity (S, D and Y) and low infectivity (W and P). Analysis of CMLA, detergent-stripped (CTAB) and I-labelled surface larval proteins was made by SDS—PAGE under reducing conditions. Differences in antigen profiles were seen in all antigen preparations, being most noticeable in CTAB and125I-labelled proteins from W and P isolates. Antigen recognition by polyclonal infection-derived antisera and by monoclonal antibodies raised against theT. spiralisLondon strain (L) was studied in the W (Arctic) and S (Spanish) isolates. Polyclonal antisera recognized different antigens in the S and W isolates, as did the monoclonal antibody, although recognition was more restricted. Neither antibody recognized a 64 kDa band in the W isolate which was clearly visible in the others tested.
Fasciola hepatica: the effect of the microtubule inhibitors colchicine and tubulozole-C on the ultrastructure of the adult fluke
Authors: Stitt A. W. , Fairweather I.
Published: June 2009

The effect of the microtubule inhibitors coichicine (1×10−3M) and tubulozole-C(1×10−6M) on the ultrastructure of adultFasciola hepaticahas been determinedin vitroby transmission electron microscopy (TEM), using both intact flukes and tissue-slice material. With colchicine treatment, the apical membrane of the tegument became increasingly convoluted and blebbed, while accumulations of T1 secretory bodies occurred in the basal region of the syncytium, leading to progressively fewer secretory bodies in the syncytium. In the tegumental cells there were distinct accumulations of T1 secretory bodies around the Golgi complexes, which remained active for up to 12 h incubation. Tubulozole-treated flukes showed more severe effects, with initial accumulations of secretory bodies, both at the tegumental apex and base. This was followed in the later time-periods by the sloughing of the tegumental syncytium. In the underlying tegumental cells, the granular endoplasmic reticulum (GER) cisternae were swollen and disrupted, becoming concentrated around the nucleus. The Golgi complexes were dispersed to the periphery of the cells and gradually disappeared from the cytoplasm. After treatment with both drugs, the cell population in the vitelline follicles was altered, with an abnormally large proportion of stem cells and relatively few intermediate type I cells. The nurse cell cytoplasm became fragmented and was no longer in contact with the vitelline cells, while the shell globule clusters within the intermediate type 2 and mature cells were loosely packed. In the mature vitelline cells, ‘yolk’ globules and glycogen deposits became fewer than normal and lipid droplets were observed. The results are discussed in relation to the different modes of action of the two drugs and potential significance of this to anthelmintic (benzimidazole) therapy.
Immunological relationships during primary infection withHeligmosomoides polygyrus. Regulation of fast response phenotype by H-2 and non-H-2 genes
Authors: Wahid F. N. , Behnke J. M.
Published: June 2009

The inheritance of response phenotype toHeligmosomoides polygyruswas investigated in Fl hybrid progeny of fast and slow responder mouse strains. The fast responses of SJL(H-2s) and SWR(H-2q) mice were mediated by dominant genes complementing each other in Fl hybrids which lost worms earlier and produced faster parasite-specific IgG1 antibody responses than either parent. However, the response of Fl hybrids from crosses of C57BL/10 (B10, H-2b) mice with either SJL or SWR differed from that of the parental strains and from each other: (B10 × SWR)F1 lost worms earlier than SWR whilst (B10 × SJL)F1 lost worms later than SJL mice. The Fl progeny of SJL mice with congenic strains B10.G (H-2q) and B10.S (H-2s) lost worms as quickly as SJL. Therefore, the response phenotype mediated by the genome of SJL mice was unaffected by H-2 heterozygosity (with H-2q) or homozygosity (H-2s) despite heterozygosity with B10 background genes, but was slowed significantly by heterozygosity with H-2b. All hybrids involving heterozygosity with B10, irrespective of MHC haplotype or background, failed to clear worms completely, in each case a proportion of mice harbouring residual worm burdens after loss of worms from parental strains.
The influence of genes mapping within the major histocompatibility complex on resistance to Trichuris muris infections in mice
Authors: Else K. J. , Wakelin D. , Wassom D. L. , Hauda K. M.
Published: June 2009

Two panels of H-2 recombinant strains of mice were used in an attempt to map the H-2-linked genes which control resistance to infection with Trichuris muris. Response phenotypes could be related to the presence of ‘resistance’ (q, b) or ‘susceptibility’ (k, d) alleles at I-A. The influence of these genes was modulated by other alleles, particularly q or d alleles, at the D end of the H-2. Absence of I-E molecules correlated with resistance to infection in some but not all strains studied. Thus the (B10.BR × B10.G) Fl strain which expressed I-Ek gene products was resistant to infection. A study of the time-course of infection in strains of mice expressing q alleles throughout the H-2 on 4 different genetic backgrounds (NIH, SWR, DBA and B10) revealed that most strains were resistant to infection. However, the DBA/1 strain exhibited differential responsiveness, 4 out of 6 individuals harbouring mature adult parasites on day 35 post-infection.
Nuttallia meri sp.nov.—a new piroplasm from Psammomys obesus in the lower Jordan Valley
Authors: Gunders A. E.
Published: June 2009

A piroplasm was isolated from a wild-caught Psammomys obesus from the lower Jordan Valley. In wild-caught Psammomys the infection is submicroscopic or of very low intensity, but rises sharply following splenectomy. The animal from which the piroplasm was isolated died with a 44 % parasitaemia and haemoglobinuria, following splenectomy.

The piroplasm was transmissible to clean, laboratory-bred Psammomys, to hamsters and Meriones. It was not transmissible to, or gave rise only to transient infections in, adult mice, rats, Mastomys, Acomys and Arvicanthis. Suckling mice and rats showed low parasitaemias for a few days, although division forms of the parasite were observed.

No protective cross-immunity with Nuttallia danii was observed.

On the basis of its measurements, spectrum of infectivity to experimental animals and absence of cross-immunity with N. danii, the piroplasm of Psammomys is considered to be a new species.

The name Nuttallia meri, sp.nov. in memory of the late Prof. Gr. G. Mer, is proposed for this piroplasm of Psammomys obesus.

I should like to express my appreciation of the excellent technical assistance provided by Mrs Miriam Sarfatti and Mr A. Bortinger, and to thank Dr Y. Schlein for his help with some of the drawings. I am particularly indebted to Dr A. Hadani of the Kimron Veterinary Institute for providing me with Meriones and testing N. meri in his laboratory.

This study was supported by the Reubin Kunin and Samuel Lunenfeld Medical Research Foundation - to which grateful acknowledgement is made.
Genetically discrete populations of Trypanosoma congolense from livestock on the Kenyan coast
Authors: Knowles G. , Betschart B. , Kukla B. A. , Scott J. R. , Majiwa P. A. O.
Published: June 2009

Twenty-seven stocks of Nannomonas trypanosomes isolated from livestock in 1982 on a ranch at Kilifi on the Kenyan coast were characterized by isoenzyme electrophoresis and by the abilities of the parasite's DNA to hybridize to two repetitive sequence DNA probes. Allthe Kilifi stocks which were examined had isoenzyme patterns which were markedly different from the 75 patterns previously described from 78 stocks of Trypanosoma congolense. On average only 15% of the enzyme bands present in the Kilifi stocks were present in those stocks of T. congolense which had previously been surveyed for isoenzymes. The DNA from all the Kilifi stocks which had been examined for isoenzymes hybridized with only the repetitive sequence probe isolated from a clone of a Kilifi stock. In contrast, the DNA from all 27 Kilifi stocks failed to hybridize with a repetitive sequence probe isolated from a clone from a different stock of T. congolense. Thus, the trypanosomes in all the Kilifi stocks examined were both phenotypically and genotypically discrete. These genetically discrete trypanosomes have also been detected in 2 stocks isolated from livestock from another location on the Kenyan coast. The results show that there is a wide range of genetic heterogeneity within the trypanosomes currently classified as T. congolense. We suggest that the limits of this genetic heterogeneity could represent incipient speciation.
Criteria for a proof of migration routes of immature parasites inside hosts exemplified by studies of Strongyloides ratti in the rat
Authors: Tindall N. R. , Wilson P. A. G.
Published: June 2009

The first rigorous proof applicable to the migration pathway of an infective juvenile macroparasite inside its host is presented. Third-stage larvae of a homogonic strain of Strongyloides ratti applied in exact doses of less than 20 to the skin of the flank of young rats were recovered 16–40 h later in the naso-frontal part of the head. The peak proportion of the dose recovered between 20 and 25 h in this site had a mean value of 0·316 ± 0·021 in 48 animals. In 40 other rats infected simultaneously the mean proportion of the dose that reached the small intestine was at least 0·837+0·013. Proof resides in verification of the inequality > 1. With appropriate statistical tests the excess of the sum of the means of these two proportions over unity is shown to have a probability of occurring by chance of 1 in 3·5 × 106. Thus it is effectively certain that the naso-frontal portion of the head is part of at least one pathway taken by this parasite on its way from the skin to the intestine of its host. By suitable protection of the infection site it was confirmed that migration to the head was achieved by an internal route and not as a result of grooming. Larvae were recovered from the cranium in the same rats over the period 15–40 h, but the peak proportion of the dose occurred at 20 h, and < in this location. Whether the cranium is also part of the pathway is therefore still undecided. The significance of this novel analysis in the general context of in-host migration of infective stages is discussed and it is concluded, following its application to data sets from other authors, that the only cases in which proof can be demonstrated are the anterior skull of the rat for S. ratti (present data) and the lung of the same host for Nippostrongylus brasiliensis (Twohy, 1956).
Transformation in vitro of Leishmania mexicana amastigotes to promastigotes: nutritional requirements and the effect of drugs
Authors: Hart D. T. , Vickerman K. , Coombs G. H.
Published: June 2009

An in vitro system is described in which over 85% of a population of Leishmania mexicana mexicana amastigotes transforms to promastigotes within 48 h. The differentiation process involves 3 morphologically and biochemically distinct intermediates, including a division stage. Cell division is shown to be necessary for complete development to promastigotes. Foetal calf serum (FCS) has been found to be an essential component of the medium for high percentage transformation to be achieved. One of the important components of the FCS has been identified as non-esterified fatty acids, and these support a relatively high percentage of amastigotes through transformation in the absence of FCS, possibly due to their use as energy substrates. Only small numbers of amastigotes transform to promastigotes if glucose or amino acids are the only energy substrates available. Transformation is inhibited by a number of metabolic inhibitors including anti-leishmanial and other anti-protozoal drugs. The stage at which inhibition is apparent varies with the inhibitor. It is suggested that the system described for the transformation in vitro of L. m. mexicana amastigotes to promastigotes may be the best method available at present for studying the metabolism and drug sensitivity of amastigotes free from possible interference by host macrophage components.
Antigenic variation in cyclically transmittedTrypanosoma brucei. Variable antigen type composition of the first parasitaemia in mice bitten by trypanosome-infectedGlossina morsitans
Authors: Hajduk S. L. , Vickerman K.
Published: June 2009

Tsetse flies were infected with 5 different variable antigen types (VATs) or with a mixture of VATs of the AnTAR 1 serodeme ofTrypanosoma brucei. Metacyclic forms from the salivary glands of infected flies were used to initiate infections in mice. Immunofluorescence and trypanolysis reactions employing 24 monospecific antisera were used to analyse the VATs present in the mice following cyclical transmission. Regardless of the VAT used to infect tsetse flies, the first VATs detectable in the bloodstream were those previously identified as metacyclic VATs (M-VATs). These were present until at least 5 days after infection, at which time lytic antibodies against at least 2 of the M-VATs were detectable in the blood of infected mice. In mice immunosuppressed by X-irradiation the M-VATs were detectable in the bloodstream for longer periods, but the percentage of the population labelled with anti-metacyclic sera showed a decrease on day 5 as in non-irradiated animals. The VAT ingested by the tsetse was always detectable early during the first parasitaemia following cyclical transmission and was usually the first VAT detected after the M-VATs. Neutralization of selected M-VATs before infecting mice resulted in elimination of the neutralized M-VAT from the first parasitaemia but had no effect on the expression of other VATs in the early infection.
Activation of protein kinase C by phorbol esters disrupts the tegument of Schistosoma mansoni
Authors: Wiest P. M. , Kunz S. S. , Miller K. R.
Published: June 2009

The tegument of the human parasite Schistosoma mansoni is critical for parasite survival within the mammalian host. The role of protein kinase C (PKC), a major effector molecule in the phosphoinositide pathway, in maintaining the structural organization of this syncytial layer was examined in adult worms. Phorbol 12-myristate, 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB), phorbol esters that activate PKC, induced formation of surface vesicles as determined by light and scanning electron microscopy. Similar results were seen with sn-2-dioctanoyl-glycerol, a synthetic analogue of diacylglycerol. No effect was seen in parasites incubated with 4-a-phorbol ester or a isomers of PMA or PDB, compounds that do not activate PKC. Vesicle formation was reversible in parasites treated with sn-2-dioctanoyl-glycerol but not with phorbol esters. The tegument of male worms was more sensitive to the effect of phorbol esters than females. Transmission electron microscopy revealed vacuolization of the tegument. These data suggest that signal transduction pathways may have a critical role in the maintenance of the structural integrity of the tegument of parasitic helminths.
Schistosomicidal activities ofLymnaea stagnalishaemocytes: the role of oxygen radicals
Authors: Adema C. M. , Van Deutekom-Mulder E. C. , Van Der Knaap W. P. W. , Sminia T.
Published: June 2009

Macrophage-like defence cells (haemocytes) of the pond snailLymnaea stagnalismediate cytotoxicity through reactive oxygen intermediates (ROIs). This activity is NADPH-oxidase dependent, as in mammalian phagocytes during the respiratory burst. In this study, mother sporocysts of schistosomes, the compatibleTrichobilharzia ocellataand the incompatibleSchistosoma mansonievokein vitroROI activities (detected by luminol dependent chemiluminescence, LDCL) fromL. stagnalishaemocytes.S. mansoniis encapsulated by haemocytes and eliminated, whereasT. ocellataescapes encapsulation and survives. Both schistosomes were equally susceptible toin vitrooxidative damage from exposure to hydrogen peroxide and to ROIs generated by a xanthine/xanthine oxidase system. Protocatechuic acid, a specific antagonist of NADPH-oxidase, delayed the killing ofT. ocellataandS. mansonisporocysts by haemocytes of resistant snails (Biomphalaria glabrata and L. stagnalis, respectively). We conclude that ROIs take part in haemocyte-mediated cytotoxicity. However, neither a snail's capability to generate ROIs, nor a schistosome's susceptibility to ROIs, determine snail/schistosome incompatibility. Snail/schistosome compatibility is rather determined by the parasite's ability modulate haemocyte behaviour such that effective encapsulation and the generation of lethal concentrations of ROIs are prevented.
Comparison of the proteins in salivary glands, saliva and haemolymph of Rhipicephalus appendiculatus female ticks during feeding
Authors: Wang H. , Nuttall P. A.
Published: June 2009

To compare the proteins in salivary glands, saliva and haemolymph of Rhipicephalus appendiculatus female ticks, antisera were prepared from guinea-pigs immunized with soluble denatured salivary gland extracts (SGE). The extracts were derived from R. appendiculatus female ticks that were either unfed (day 0) or partly fed (day 6). The sera were used in immunoblotting, following SDS–polyacrylamide gel electrophoresis, to examine the antigen profiles during the course of tick feeding on guinea-pigs. Day 0 and day 6 SGE antisera appeared to detect common proteins in the different tick samples. For example, haemolymph apparently shared some of the small protein bands (31·5–34 kDa) detected in SGEs. These small proteins appeared in both samples at the same stage of feeding, suggesting that haemolymph and salivary glands not only have common antigens but may also share some functions. Furthermore, a number of protein bands were detected in haemolymph before they were apparent in the salivary glands or saliva. Thus some antigens detected in the salivary glands and saliva may be derived from the haemolymph. The results indicate that the host may be exposed to tick saliva antigens that are also present in the haemolymph. We discuss the significance of these observations with regard to the induction of host immunity to ticks and the development of tick vaccines.
Excretion of host immunoglobulin in tick saliva and detection of IgG-binding proteins in tick haemolymph and salivary glands
Authors: Wang H. , Nuttall P. A.
Published: June 2009

Host immunoglobulin G (IgG) crossed the gut wall into the haemocoel of adult Rhipicephalus appendiculatus female ticks when they fed on guinea-pigs. Guinea-pig IgG was also found in saliva of the feeding ticks. The concentration and antibody activity of IgG in haemolymph, salivary gland extract (SGE) and saliva at different stages of tick feeding were detected by enzyme-linked immunoassay. Specific activity of the IgG in tick samples was determined by feeding ticks on guinea-pigs which were immunized with killed Escherichia coli: 35–42% of the antibody activity in guinea-pig immune serum remained in the tick samples. The high relative concentration of IgG in tick saliva at later stages of feeding suggests that the tick may have a mechanism for getting rid of foreign proteins via the salivary gland. Such a mechanism could involve lgG binding proteins (1GBPs) which were found in both haemolymph and SGE of female ticks at day 6 of feeding using a guinea-pig IgG–agarose affinity column. In female ticks, the Mr of 1GBPs in SGE (23 and 57 kDa) were less than those in haemolymph (78 and > 100 kDa). The existence of 1GBPs in both the tick salivary gland and haemolymph indicate that haemolymph and salivary gland cooperate to remove foreign proteins, e.g. host immunoglobulin, from the body during feeding. This mechanism may be a part of the tick self-defence system.
GABA in the nervous system of parasitic flatworms
Authors: Eriksson K. S. , Maule A. G. , Halton D. W. , Panula P. A. J. , Shaw C.
Published: June 2009

In an immunocytochemical study, using an antiserum and a monoclonal antibody specific for the amino acid, γ-aminobutyric acid (GABA), GABA-like immunoreactivity (GLIR) has been demonstrated for the first time in parasitic flatworms. In Moniezia expansa (Cestoda), GLIR was seen in nerve nets which were closely associated with the body wall musculature and in the longitudinal nerve cords. In the liver fluke Fasciola hepatica (Trematoda), the GLIR occurred in the longitudinal nerve cords and lateral nerves in the posterior half of the worm. GLIR was also detected in subtegumental fibres in F. hepatica. The presence of GABA was verified, using high-pressure liquid chromatography coupled with fluorescence detection. The concentration of GABA (mean ± S.D.) in M. expansa anterior region was 124·8 ± 15·3 picomole/mg wet weight, while in F. hepatica it was 16·8 ± 4·9 picomole/mg. Since several insecticides and anti-nematodal drugs are thought to interfere with GABA-receptors, the findings indicate that GABAergic neurotransmission may be a potential target for chemotherapy in flatworms too.
Structure and ultrastructure of muscle systems withinGrillotia erinaceusmetacestodes (Cestoda: Trypanorhyncha)
Authors: Ward S. M. , McKeer G. , Allen J. M.
Published: June 2009

Three distinct muscle types have been identified within the metacestode ofGrillotia erinaceus. These consist of peripheral somatic myofibres plus two muscle systems directly involved in parasite attachment to the host, i.e. the tentacular bulb and its antagonistic retractor muscle. In common with other cestodes the somatic muscle consists of smooth-type fibres running longitudinally and obliquely to the main body axis. The retractor muscle consists of myofibres with centrally displaced nuclei. Upon contraction these latter fibres become spirally orientated causing the muscle to coil and lateral membranes to become elevated as spikes. Definitive nerve processes have not been identified within somatic or retractor muscle. Individual tentacular bulbs form the proximal terminus for a closed hydraulic system. Each bulb consists of overlapping, contrarotating myofibres which display obvious striations; the striations appear in alternate fibres to be in transverse and oblique planes. Adjacent myofibres are separated by approximately 0·5 μm, possess abundant mitochondria and have shallow t-tubules plus associated vesicles of sarcoplasmic reticulum at each Z line. Thick myofilaments are surrounded by 13, shared, thin myofilaments. Close neuronal control for the bulb muscle is suggested by the presence of obvious motor end-plates which contain both lucent and dense neurovesicles.
Echinococcus granulosus (Cestoda): uptake of L-amino acids by secondary hydatid cysts
Authors: Jeffs S. A. , Arme C.
Published: June 2009

The uptake of cycloleucine, L-proline, L-alanine and L-threonine by secondary hydatid cysts ofEchinococcus granulosus(U.K. horse strain 3–8 mm in diameter, derived from Balb/c mice infected 300–400 days previously) occurs by passive diffusion into the cyst wall (laminated layer plus germinal layer) and by mediated mechanisms into the fluid-filled interior. The maximal concentrations of these compounds are achieved after incubation for 2 hin vitroand approach thosein vivo.Ktand Vmaxvalues describing the uptake of these compounds are given. The flux rates for these compounds are extremely slow compared to those obtained with the protoscolex. A rationale for standardizing the experimental method for uptake studies with hydatid cysts is described.
Evidence for the absorption and synthesis of 5-hydroxytryptamine in perfused muscle and intestinal tissue and whole worms of adultAscaris suum
Authors: Chaudhuri J. , Martin R. E. , Donahue M. J.
Published: June 2009

The metabolites of 5-hydroxytryptamine (5-HT, serotonin) namely, L-tryptophan, 5-hydroxytryptophan, 5-hydroxyindole acetic acid and 5-hydroxytryptophol were measured in perfused tissue and whole worms from adult femaleAscaris suumusing reversed-phase liquid chromatography with electrochemical detection. The intracellular levels of each metabolite were quantitated in response to several physiological effectors but only Ltryptophan (TRP) caused dose-dependent changes in these metabolites. Serotonin itself could also be absorbed by perfusedA. suummuscle and intestinal tissue. When liveA. suumwere tied at the anterior and posterior regions to restrict TRP absorption by the intestine, TRP was absorbed through the cuticle and converted into 5-HT by the muscle tissue. In untied live parasites TRP absorption was observed in both muscle and intestinal tissue. Collectively, the data indicated that 5-HT may be either absorbed directly or synthesizedde novofrom absorbed TRP in the isolated tissue ofA. suum. The 5-HT, in the live adult femaleA. suum, can be synthesizedde novofrom TRP, or 5-HT can be absorbed from the environment both through the cuticle and by the intestine of living parasites. Data also indicated that there was preferential sequestering of 5-HT and the metabolites of 5-HT in the anterior tissues of the worms.
Glycans withN-acetyllactosamine type 2-like residues covering adultSchistosoma mansoni, and glycomimesis as a putative mechanism of immune evasion
Authors: Schmidt J.
Published: June 2009

Glycans at the surface of adultSchistosoma mansoniwere investigated with gold-labelled lectins. The fragile complex of the glycans with the outer membranes could be preserved for electron microscopy by avoiding extensive pre-fixation with aldehydes and by introducing osmium-ferrocyanide as a membrane fixative. Male and female worms were entirely covered with glycans that intensely bound lectins fromErythrina cristagalliandDatura stramonium, suggesting that galactose(β1–4)N-acetylglucosamine residues occur in high numbers in the surface glycans. Similar staining was obtained with lectins fromTriticum vulgaris, Glycine maxandRicinus communisagglutinin I, which react withN-acetylglucosamine or terminal galactose residues and bind non-selectively with high affinity toN-acetyllactosamine. Fucose,N-acetylgalactose and sialic acid were not detected with lectins and sialidase treatment. The tegument contained an abundance of glycans with the same lectin reactivities as the surface-expressed molecules, indicating that the worms synthesize and replenish their surface glycans and do not merely adsorb host substances. Glycomimesis is discussed as a mechanism of immune evasion in view ofN-acetyllactosamine being a common and weakly immunogenic component in glycans of vertebrate hosts.S. mansonimight disguise themselves with the glycans against attack by immune effectors.
The action of serotonin and the nematode neuropeptide KSAYMRFamide on the pharyngeal muscle of the parasitic nematode,Ascaris suum
Authors: Brownlee D. J. A. , Holden-Dye L. , Fairweather I. , Walker R. J.
Published: June 2009

The pharyngeal component of the enteric nervous system of the parasitic nematode,Ascaris suumexhibits immunoreactivity for serotonin (5-hydroxytryptamine or 5-HT) and for FMRFamide-like peptides. This paper describes the application of anin vitropharmacological approach to investigate the functional role of 5-HT and FMRFamide-like peptides. The pharyngeal pumping behaviour ofAscaris suumwas monitored using a modified pressure transducer system which measures pharyngeal pressure changes and therefore pumping. The pharynx did not contract spontaneously; however, 5-HT (10-1000 μM) stimulated pumping at a frequency of 0·5 Hz. FMRFamide had no apparent effect on pharyngeal pumping. The native nematode FMRFamide-related peptide (FaRP), KSAYMRFamide inhibited the pumping elicited by 5-HT. The duration of inhibition was dose-dependent (0·1-1000 nM) with a threshold of 0·1 nM. In 4 preparations, the inhibition of the pharyngeal muscle was preceded by an initial excitation and increase in the amplitude of pharyngeal pressure changes. The pharynx is involved in various nematode processes, including feeding, regulation of hydrostatic pressure and excretion. The role of 5-HT and KSAYMRFamide in the pharyngeal function of nematodes is discussed.
Immune suppressive virus-like particles in a Drosophila parasitoid: significance of their intraspecific morphological variations
Authors: Dupas S. , Brehelin M. , Frey F. , Carton Y.
Published: June 2009

The Eucoilid parasitoid Leptopilina boulardi is able to suppress its host Drosophila melanogaster immune reaction. Some strains, however, are non-immune suppressive to that host. Virus-like particles (VLPs) responsible for the immune suppressive ability were investigated in different strains of L, boulardi with histochemical and ultrastructural techniques. Membrane-bound particles containing vesicles were observed in the reservoir of the long gland and also in the egg canal of the ovipositor. These particles are homologous with the immune suppressive VLPs already described in the reservoir of L. heterotoma. Similarities were also observed with the L2 particles described previously around the chorion of the parasitoid egg after infestation. A weak positive DNA specific histochemical reaction was observed inside the reservoir and at the ultrastructural level. Feulgen-derived techniques demonstrated that the reaction was localized inside the particles. The morphology of the particles as well as the immune suppressive ability varied between strains. Two morphotypes of VLPs are described; the ‘Is’ morphotype (always observed in immune suppressive or Is strains) and the ‘NIs’ morphotype (observed in the non-immune suppressive or NIs strain). The hybrids between Is and NIs strains produce a third type of particle, the ‘His’morphotype with half-immune suppressive ability and intermediate morphology. The origin of the particles' immune suppressive activity against D. melanogaster is discussed within the scope of host specificity.
A method for the recovery of nematode eggs from faeces
Authors: Wassall D. A. , Denham D. A.
Published: June 2009

A simple apparatus for the collection of helminth eggs from faeces by means of a gas-circulated saturated salt solution is described. Nearly all the Nematodirus spp. eggs in both bovine and ovine faeces were recovered and shown to be viable.