bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunocytochemical study on biologically active neurosubstances in daughter sporocysts and cercariae of Trichobilharzia ocellata and Schistosoma mansoni
Authors: Solis-soto J. M. , De Jong Brink M.
Published: June 2009

Immunocytochemical techniques applied to sections and whole-mount preparations of cercariae from two species of trematodes, Trichobilharzia ocellata and Schistosoma mansoni, revealed the occurrence of immunoreactivity (IR) to several neurosubstances in the nervous system (NS). Immunostaining was localized in cerebral ganglia, in the main commissure, in anterior and posterior nerve trunks, as well as in a pair of nerve fibres running along the tail. In T. Ocellata, immunoreactivity (IR) was observed with antisera raised against: glutamate, FMRFamide, catch-relaxing peptide (CARP), small cardiac peptide B (SCPB), arg-vasotocin (AVT), arg-vasopressin (AVP), and substance P. In S. mansoni antisera raised against glutamate, FMRFamide, CARP, SCPB, α-caudodorsal cell peptides (α-CDCP), and cholecystokinin (CCK) showed neuronal IR. With the other 51 antisera tested no IR was observed. With anti-APGWamide, IR was observed outside the NS in cells of the wall of the daughter sporocyst and in flame cells of cercariae of T. ocellata. IR to FMRFamide was present in the escape glands of the intrasporocystic cercariae of T. ocellata and S. mansoni. IR to somatostatin was observed in subtegumental parenchymal cells of cercariae of S. mansoni. IR to met-enkephalin was present in cells of the cercarial embryos and in undifferentiated cells in developing cercariae. Trematodes are, together with cestodes, phylogenetically the oldest classes in which glutamate-like material and immunopositivity to a number of neuropeptides isolated from invertebrates has been demonstrated. The results are discussed in relation to immunocytochemical data obtained for other platyhelminths, to endogenous functions of the immunopositive materials, and to their possible role in parasite–host interactions.
Detection of trypanosome infections in the saliva of tsetse flies and buffy-coat samples from antigenaemic but aparasitaemic cattle
Authors: Majiwa P. A. O. , Thatthi R. , Moloo S. K. , Nyeko J. H. P. , Otieno L. H. , Maloo S.
Published: June 2009

Relatively simple protocols employing non-radioactive DNA probes have been used for the detection of African trypanosomes in the blood of mammalian hosts and the saliva of live tsetse flies. In combination with the polymerase chain reaction (PCR), the protocols revealed trypanosomes in buffy-coat samples from antigenaemic but aparasitaemic cattle and in the saliva of live, infected tsetse flies. Furthermore, the protocols were used to demonstrate concurrent natural infections of single tsetse flies with different species of African trypanosomes.
Detection of density-dependent growth and fecundity of helminths in natural infections
Authors: Shostak A. W. , Scott M. E.
Published: June 2009

Density-dependent constraints on parasite growth, survival or reproduction are thought to be important in preventing the unchecked increase in parasite numbers within individual hosts or host populations. While it is important to know where, and with what severity, density dependence is acting within the parasite life-cycle, interpretation of data from natural infections is difficult. In this paper, we present a Monte Carlo simulation technique for examining such data for evidence of density dependence. We also describe how this technique may be used to distinguish among mechanisms hypothesized to generate density-dependent phenomena.
Paramyosin isoforms ofSchistosoma mansoniare phosphorylated and localized in a large variety of muscle types
Authors: Schmidt J. , Bodor O. , Gohr L. , Kunz W.
Published: June 2009

Paramyosin, although a widely distributed muscle component among invertebrates, has hitherto not clearly been shown to occur in the muscles of schistosomes. Instead, it has been reported to occur in the tegument. In the present study, a specific antibody reacting with each of 10 isoforms of paramyosin was used for light microscopical immunolocalization in sections ofSchistosoma mansoni. Specimens were fixed by a new method to immobilize antigens with uranyl acetate–trehalose–methanol. In cercariae, schistosomula, and adults, the circular and longitudinal muscles of the body wall, the dorsoventral muscles and those surrounding the gut and the pharynx as well as the fast moving cross-striated muscles of the tail of cercariae intensely reacted with the antibody. However, neither immunohistologically nor on Western blots of isolated tegument, were indications found for the presence of paramyosin in the tegument.In vivophosphorylation and binding of anti-phospho-tyrosine and anti-phospho-serine antibodies show phosphorylation of paramyosin which probably is responsible for the generation of the isoforms.
Intestinal parasite burden in five troops of olive baboons (Papio cynocephalus anubis) in Gombe Stream National Park, Tanzania
Authors: Müller-Graf C. D. M. , Collins D. A. , Woolhouse M. E. J.
Published: June 2009

A cross-sectional parasitological study of a population of wild olive baboons (Papio cynocephalus anubis), consisting of 5 troops, was conducted in Gombe Stream National Park. Baboons were individually recognizable. Information on age, sex, troop membership, reproductive status, social rank and life-history of each individual baboon could be related to parasite infection. Seven helminth taxa and 2 protozoan taxa were found. All baboons were parasitized by at least 1 taxon. Distributions of helminths were aggregated among hosts. There were significant differences among troops in the prevalence of all but 2 of the recorded helminths. Age had a significant impact on the prevalence and intensity ofStrongyloidessp. No significant effect of sex on the prevalence of infection could be detected. There was some indication that female reproductive status was related toTrichurisegg output. In contrast to a previous study, no significant correlations between parasite infection and social rank could be found. Troop membership constituted the predominant factor contributing to heterogeneity of prevalence of infection. This suggests that spatial location and/or genetics may be important in determining levels of parasite infection.
Experimental study on the influence of paper and pulp mill effluent on the gill parasite communities of roach (Rutilus rutilus)
Authors: Bagge A. M. , Valtonen E. T.
Published: June 2009

Roach (n= 81) caught on 23 May, 1992 from oligotrophic, unpolluted Lake Peurunka were kept in cages over a 2-week period before moving half of the fish to nearby Lake Vatia, which is influenced by pulp mill effluents. Before moving the fish gill parasites were examined from 9 fish; 5Dactylogyrusspecies,Gyrodactylussp. andParadiplozoon homoionwere found, the main components of the infracommunities being dactylogyrids. Afterwards, 5 fish from each lake were studied weekly between 1 July and 17 August. Metazoan parasites were recorded from gill arches divided into 4 sections along the dorso-ventral axis.D. crucifer, D. nanus, D. micracanthusandD. suecicusoccurred in both lakes throughout the study.Gyrodactylussp., Ergasilus briani andP. homoionoccurred in low numbers in both lakes. Differences between the lakes were seen in the prevalence ofD. micracanthuswhich was higher in Lake Vatia and significantly increased abundances ofD. crucifer, D. nanusandD. micracanthusin Lake Vatia. Abundances of otherDactylogyrusspecies remained, on average, at the same level in both lakes. No change during the experiment was recorded in the location of the two most common species,D. cruciferandD. nanus, on the host gills in either of the lakes, both species favouring the 2nd and 3rd gill arches and especially the inner parts of the gills. The apparent lack of competition between the 2 most commonDactylogyrusspecies indicates that no limitation of resources on roach gills occurred. This was also confirmed by the increased overlapping indices with increasing abundances between the two most common species in Lake Vatia.
Studies on ascaridoid nematodes in pythons: the life-history and development of Ophidascaris moreliae in Australian pythons
Authors: Sprent J. F. A.
Published: June 2009

Several species of Australian python, Morelia spilotes variegatus, Liasis amethy-stinus, L. fuscus and L. childreni, were experimentally infected with eggs of Ophidascaris moreliae and the development of the larvae described. The first moult occurred in the egg, which survived and remained infective for over 7 years in moist conditions. The first moult occurred in 12 days and the second-stage larva in the egg was infective to mice in 14–21 days. After ingestion the larvae migrated to liver and lungs and in 21 days were mainly distributed throughout the subcutaneous tissues, particularly in the neck region and behind the ears. Growth occurred to about 8 mm; the larvae attained their infectivity for pythons after 5 weeks and retained it for more than a year. The second moult was not observed but it was assumed that the third stage was infective for pythons. Development to about the same length occurred in guinea-pigs and indigenous and laboratory rats and in the bandicoot (Isoodon obesulus). In the possum (Tricho-surus sp.) a more rapid growth occurred to about the same length. No growth occurred in tadpoles.

After ingestion by pythons larvae migrated to the lungs, where they remained for 3 months or more, grew to a length of 45 mm and underwent the third moult. Larvae removed from the lungs and reingested by pythons returned to the lungs if they had been in the first python for less than 60 days. After this time, they remained in the stomach of the second python. During the third moult larvae underwent a marked constriction of the anterior end, moved up the trachea and became attached in the upper oesophagus as fourth-stage larvae. In mouse-infected M. spilotes the third moult occurred at 117 days at a length of 23–45 mm; fourth-stage larvae measured 34–50 mm. The fourth moult occurred in the stomach at 318 days at a length of 37–55 mm. The smallest adult specimens found were a 55 mm male and a 63 mm female. Development to the adult stage was only observed in M. spilotes variegatus. In other python species only pre-adult forms were recovered. It appeared that development may be retarded at the fourth moult during the winter. The morphology of the larvae during the five stages of development is described. It is concluded that the main growth phases are the third stage in the lungs of the python and the adult stage in the stomach of the python. Encapsulated forms were found only in the tissues of intermediate hosts. The larvae from mouse tissues emerged from the capsules during putrefaction and survived for several weeks in water.

Acknowledgement is made to the able technical assistance of Miss Marian Hollis. Financial assistance for this study was provided under grants from the Australian Research Grants Committee and the United States Department of Health, Education and Welfare no. A 107023–02.
Monitoring the efficacy of different doses of praziquantel by quantification of circulating antigens in serum and urine of schistosomiasis patients
Authors: van Lieshout L. , de Jonge N. , El-Masry N. , Mansour M. M. , Bassily S. , Krijger F. W. , Deelder A. M.
Published: June 2009

We evaluated the quantitation of two schistosome circulating antigens in serum and urine as a tool for the assessment of the efficacy of praziquantel dosage regimens (40 versus 60 mg/kgbw). In addition we compared the efficacy of two different brands of praziquantel (Biltricide® and Distocide®), given at the same dosage (40 mg/kgbw). Thirty five Egyptian hospitalized schistosomiasis mansoni patients participated in this study. Thirteen patients (Group 1) received 60 mg/kgbw Biltricide®, administered in 3 oral doses of 20 mg in one day; 22 individuals (Group 2) were treated with 40 mg/kgbw (12 Biltricide®, 10 Distocide®), given in one oral dose. Circulating anodic antigen (CAA) and circulating cathodic antigen (CCA) were quantitated by monoclonal antibody-based ELISA's before, and 1, 3 and 6 weeks after chemotherapy. Before treatment, all patients were positive for at least one of the circulating antigen assays. Three to six weeks after treatment significantly more patients were found to be negative in Group 1 compared to Group 2 (X2 = 7·13, P = 0·008, n = 35). Also the levels of CCA and CAA in serum and of CCA in urine were found to be significantly higher in Group 2 (Mann- Whitney U < 85, P < 0·05, n = 35). These results were confirmed by parasitological data. No differences were found between treatment with Biltricide® or Distocide®. Our results indicate that praziquantel treatment of schistosomiasis with 60 mg/kgbw divided in 3 doses results in a higher cure rate compared to 40 mg/kgbw as a single dose, and provide further evidence for the use of the CAA and CCA assays as a sensitive method to monitor the efficacy of chemotherapy, particularly when circulating antigen assays are combined by parallel testing.
ELISAs based on recombinant antigens for sero-epidemiological studies onToxoplasma gondiiinfections in cats
Authors: Tenter A. M. , Vietmeyer C. , Johnson A. M. , Janitschke K. , Rommel M. , Lehmacher W.
Published: June 2009

Two recombinantToxoplasma gondiipolypeptides, H4 and H11, were tested as diagnostic antigens in enzyme-linked immunosorbent assays (ELISAs). The results obtained by ELISAs based on single H4 (H4-ELISA), on single H11 (H11-ELISA) and on a mixture of H4 and H11 (H4/H11-ELISA) were compared with results obtained by an ELISA based on traditional ELISA antigen (TEA-ELISA), an indirect fluorescent antibody test (IFAT), the Sabin-Feldman dye test (SFDT) and a direct agglutination test (DAT). A total of 306 cats from a suburban cat population were tested of which about 45% showed serological evidence ofT. gondiiinfection. Infection rates varied from about 32% for cats kept indoors to about 55% for stray cats. Specificities > 99% were observed for all ELISAs based on the recombinant antigens (H4-ELISA, H11-ELISA and H4/H11-ELISA). The H4/H11-ELISA also reached a sensitivity of 95% which compared very favourably with those observed for the TEA-ELISA (98%) and for the IFAT (94%). Negative and positive predictive values for the H4/H11-ELISA were 96 and < 99%, respectively. Antibody titres measured by the H4/H11-ELISA also correlated well with those measured by the SFDT and the DAT. Hence, the H4/H11-ELISA appears to be a very suitable test for sero-epidemiological studies onT. gondiiinfections in cats.
Effects of culture and praziquantel on membrane fluidity parameters of adultSchistosoma mansoni
Authors: Lima S. F. , Vieira L. Q. , Harder A. , Kusel J. R.
Published: June 2009

Membrane fluidity parameters, lateral diffusion coefficient and mobile fraction were assessed in male and femaleSchistosoma mansoniteguments immediately after their recovery from infected mice or after 24 or 48 h of culture. Our results show that male and female teguments have different properties and behave differently when in culture. In general, male worms displayed a tendency to increase their lateral diffusion coefficient while females showed a significant reduction. The effects of praziquantel (−) and praziquantel (+) on the fluidity properties of the worm surface were also studied. It was demonstrated that both enantiomers of the drug interact with the tegument inducing a decrease in the average velocity of lipid molecules. However, it is only the active form which reduces the number of molecules that are able to move. In explanation we propose that praziquantel (−) and praziquantel (+) have different ways of inserting into the tegument and that some of the effects of the drug are mediated by altering membrane fluidity.
Plagiorchis elegans: emergence, longevity and infectivity of cercariae, and host behavioural modifications during cercarial emergence
Authors: Lowenberger C. A. , Rau M. E.
Published: June 2009

We investigated changes in the behaviour of Stagnicola elodes associated with the emergence of Plagiorchis elegans cercariae. Within 15 min of the reduction in light intensity, which triggered the onset of cercarial emergence, infected snails moved to the top of the water column and remained there for 2–3 h. Seventy-nine percent of all cercariae that emerged from the snail did so during this period. Uninfected snails showed no such behavioural changes following the change in light intensity. Cercariae were released in a dense cloud around the snail at the water surface and dispersed passively. Within 3–4 h more than 80% of all cercariae had settled in the bottom 5 cm of the water column. The infectivity of cercariae increased from less than 20% upon emergence from the snail to greater than 75% 4–6 h post-emergence, and then declined steadily to below 5% by 24 h post-emergence. Cercarial longevity was greater than 30 h and exceeded the period of infectivity. This may be related to steadily falling endogenous glycogen levels. A delay in attaining maximum infectivity may represent an adaptive mechanism allowing time for cercarial dissemination, thus reducing superinfection, and subsequent parasite-associated mortality, of second intermediate hosts.
On the permeability of cestodes to colloids: an evaluation of the transmembranosis hypothesis
Authors: Lumsden Richard D. , Threadgold Lawrence T. , Oaks John A. , Arme C.
Published: June 2009

Adult Hymenolepis diminuta were tested for their ability to transport colloids under in vitro and in vivo conditions. The tracers employed included colloidal thorium dioxide (Thorotrast), carbon (Pelikan Ink), ferritin and the 14C-labelled protein fraction from Chlorella vulgaris. Though certain of these tracers were adsorbed to the external surface of the tegument plasmalemma, no evidence for the assimilation of any of these colloids was obtained in the present study. Further, significant differences in size and structure between the granular inclusions reported earlier by Rothman (1967) as assimilated colloids and the particles present in the respective colloidal suspensions were noted. Results of this investigation are interpreted as rendering untenable previous conclusions concerning transmembranosis of colloids by tapeworms.
Fine structure of the nervous system and specialized nerve endings in the miracidium of Fasciola hepatica
Authors: Wilson R. A.
Published: June 2009

The fine structure and organization of the nervous system of the miracidium is described. The central ganglion consists of a mass of nerve fibres with peripherally situated cell bodies. Tracts of fibres run outward from the central mass to the muscles of the body wall and to specialized endings. The individual fibres contain several types of inclusions and synapses are common in the neuropile.

Excluding the eyespots, four kinds of specialized nerve endings are described. Two of these types terminate at the body surface and bear ‘cilia’. The other two terminate internally, one type within the body wall and the other type laterally, slightly anterior to the central ganglion. It is suggested that the function of three of the types of ending might be sensory, detecting chemical and mechanical stimuli, and the direction of gravity. The function of the fourth type of ending is problematical but might be secretory.

I am most grateful to Dr A. Robards for use of electron microscope facilities and to Mrs J. Denison for technical assistance.
Density-dependent processes in the transmission of human onchocerciasis: intensity of microfilariae in the skin and their uptake by the simuliid host
Authors: Basáñez M. G. , Boussinesq M. , Prod'hon J. , Frontado H. , Villamizar N. J. , Medley G. F. , Anderson R. M.
Published: June 2009

The transmission success ofOnchocerca volvulusis thought to be influenced by a variety of regulatory or density-dependent processes that act at various points in the two-host life-cycle. This paper examines one component of the life-cycle, namely, the ingestion of microfilariae by the simuliid vector, to assess the relationship between intake of larvae and the density of parasites in the skin of the human host. Analysis is based on data from three areas in which onchocerciasis is endemic and includes published information as well as new data collected in field studies. The three areas are: Guatemala (Simulium ochraceum sl.), West and Central Africa (savanna members of theS. damnosumcomplex), and South Venezuela (S. guianense). The data record experimental studies of parasite uptake by flies captured in the field and fed to repletion on locally infected subjects who harboured varying intensities of dermal microfilarial infection. Regression analyses of log transformed counts of parasite burdens ingested by the flies plotted against log transformed counts of microfilariae per mg of skin revealed little evidence for saturation in parasite uptake by the flies as the intensity in the human host increased. There was a positive and highly significant rank correlation between both variables for the three blackfly species. In an alternative analysis a model was fitted to data on prevalence of flies with ingested microfilariae (mff) versus dermal mean intensities. The model assumed an overdispersed distribution of the number of mff/fly and a given functional relationship between intake and skin load. The results of both approaches were consistent. It is concluded that parasite ingestiossssn by the vector host is not strongly density dependent in the three geographical areas and ranges of dermal loads examined. It therefore appears that this transmission process is of reduced importance as a regulatory mechanism in the dynamics of parasite population growth.
Interactions between the acanthocephalansPomphorhynchus laevisandAcanthocephalus anguillaein rainbow trout: testing an exclusion hypothesis
Authors: Bates R. M. , Kennedy C. R.
Published: June 2009

Rainbow trout were infected simultaneously with cystacanths of the two acanthocephalan speciesPomphorhynchus laevisandAcanthocephalus anguillaein the laboratory. Infections consisted of varying proportions of the two species (from 0 to 100%) at low (20 cystacanths) and high (60 cystacanths) levels. Fish were sacrificed at 7, 56 and 112 days post-infection (p.i.) and the parasites recovered. At low-level infections there was a high degree of overlap in the range of intestine occupied by the two species (44·12 %) and no evidence for interspecific competition affecting either species. At high-level infections the establishment of both species was unaffected by the presence or number of individuals of the other species. The survivorship and the range of intestine occupied byA. anguillaewere found to be reduced in the presence ofP. laevis. The interaction was one-sided, asP. laevisremained unaffected byA. anguillae, and so indicated interference competition. The possibility that both intraspecific and interspecific competition are implicated in explaining the distribution of the two species in the British Isles is discussed.
Trypanosoma brucei brucei: differences in the nuclear chromatin of bloodstream forms and procyclic culture forms
Authors: Schlimme W. , Burri M. , Bender K. , Betschart B. , Hecker H.
Published: June 2009

Nucleosome filaments of two stages of the life-cycle ofTrypanosoma brucei brucei, namely bloodstream forms and procyclic culture forms, were investigated by electron microscopy. Chromatin of bloodstream forms showed a salt-dependent condensation. The level of condensation was higher than that shown by chromatin from procyclic culture forms, but 30 nm fibres as formed in rat liver chromatin preparations were not found. Analysis of histones provided new evidence for the existence of H1-like proteins, which comigrated in the region of the core histones in SDS–PAGE and in front of the core histones in Triton acid urea gels. Differences were found between the H1-like proteins of the two trypanosome stages as well as between the core histones in their amount, number of bands and banding pattern. It can be concluded thatT. b. bruceicontains a full set of histones, including H1-like proteins, and that the poor condensation of its chromatin is not due to the absence of H1, but most probably due to histone–DNA interaction being weak. It is obvious that structural and functional differences of the chromatin exist not only betweenT. b. bruceiand higher eukaryotes, but also between various stages of the life-cycle of the parasite. It is therefore not adequate to investigate the chromatin only of the procyclic culture forms as a model for all stages of the life-cycle ofT. b. brucei.
Biochemical and morphological pathology of the foot of the schistosome vector Biomphalaria glabrata infected with Schistosoma mansoni
Authors: Thompson S. N. , Lee R. W. K. , Mejia-Scales V. , El-Din M. Shams
Published: June 2009

Infection by Schistosoma mansoni resulted in morphological and biochemical changes to the foot of its intermediate host, Biomphalaria glabrata. Migration through, and emergence of cercariae from, the foot was observed and evidenced by lesions on the ciliated foot surface. This was accompanied by a significant decrease in the velocity of movement by infected individuals. In vivo31P NMR spectral analyses demonstrated that the foot of infected snails had a lower phosphoarginine (PA)/adenosine 5' triphosphate (ATP) ratio than that of uninfected controls. Moreover, kinetic experiments, employing saturation transfer, demonstrated the pseudo-first-order rate constant for the arginine kinase-catalysed exchange reaction in the forward direction, that is, PA→ATP was decreased by infection. The reverse reaction was not observed by the NMR methods used. PA was depleted upon exposure to hypoxic conditions suggesting its traditional role in preserving ATP level. Partly oxidized metabolic end-products were not observed in snails maintained under aerobic conditions, but succinate, propionate, acetate and lactate rapidly accumulated under hypoxic conditions.
The methionine synthesis cycle and salvage of methyltetrahydrofolate from host red cells in the malaria parasite (Plasmodium falciparum)
Authors: Asawamahasakda W. , Yuthavong Y.
Published: June 2009

Plasmodium falciparum, P. knowlesi and P. chabaudi showed a significant activity of methylenetetrahydrofolate reductase (MTHFR). The presence of this enzyme completes the methionine synthesis cycle, in which the one-carbon fragment from serine side-chain can be transferred to methionine. However, while metabolic labelling of methionine from l-3 [14C]serine could not be demonstrated in P. falciparum, the significance of MTHFR was implicated by a novel pathway for salvage of exogenous 5-methyltetrahydrofolate from the host cell. The methyl group of the cofactor was incorporated into methionine, and the folate cofactor was found in the same pool as that derived from de novo synthesis with paminobenzoic acid as the precursor, shown previously as polyglutamylated 5-methyltetrahydrofolate. It is proposed from these results that the function of MTHFR and the methionine synthesis cycle is not the supply of methionine, but the generation of active folate cofactors from more stable precursors salvaged by the parasites
The dynamics of intestinal helminth communities in eels Anguilla anguilla in a small stream: long-term changes in richness and structure
Authors: Kennedy C. R.
Published: June 2009

The prediction that species richness and diversity of intestinal helminth communities in eels would change over time in response to habitat changes was tested over a period of 13 years in a small stream subjected to extensive human management. Nearly all measures of helminth community structure adopted indicated a decline in richness and diversity over the first 6 years followed by a recovery over the last few years to levels unexpectedly close to those at the start of the investigation. Changes in total number of species suggested that the component community was far richer (from 3–9 species) at the end of the period. By contrast, changes in diversity and dominance measures revealed less variation than expected and suggested that there was an underlying stability of community structure characterized by high dominance by a single species, although the identity of this changed, low diversity and a large proportion of the eel population harbouring 0 or only 1 species. A similar pattern of changes was recorded in the infra-communities, where values of species richness and diversity were very similar at the commencement and termination of the study. It appeared that those helminths that colonized in the recovery period contributed to community richness but had little impact on community structure. The helminth communities clearly did change in response to habitat changes, and the evidence for a fixed number of niches and an underlying constancy in helminth community structure in eels is evaluated.
Rapid changes in the surface of parasitic nematodes during transition from pre- to post-parasitic forms
Authors: Proudfoot L. , Kusel J. R. , Smith H. V. , Harnett W. , Worms M. J. , Kennedy M. W.
Published: June 2009

All mammalian-parasitic stages of a range of nematode species investigated (Brugia pahangi, Acanthocheilonema viteae, Strongyloides ratti, Nippostrongylus brasiliensis, Trichinella spiralisandOstertagia ostertagi) labelled in a surface-restricted manner with the fluorescent lipid analogues 5-N-(octadecanoyl)aminofluorescein (AF18) or nitrobenzoxadiazole-cholesterol (NBD-chol), but failed to bind other similar probes. In contrast, the surfaces of the ‘pre-parasitic’ infective stages of these species had affinity for neither AF18 nor NBD-chol. This exclusion of lipid analogues changed rapidly upon exposure of the larvae to tissue culture conditions which mimic the mammalian tissue environment (e.g. RPMI 1640/37°C) such that the above probes could then insert into the surface layer of the larvae. The dauer larva ofCaenorhabditis elegansalso excluded the probes, but became permissive to labelling upon stimulation to emerge from the dauer state. The time taken for the surface transformation to occur ranged from less than 10 min in the vector-borne parasites to approximately 5 h in those which enter by the oral route, with direct skin-penetrators occupying an intermediate position. In all cases, the alteration proceeded too rapidly for it to have been associated with a moult. Fluorescence Recovery After Photobleaching (FRAP) studies ofA. viteaelarvae showed that approximately 50% of the AF18 probe was free to diffuse within the plane of the surface immediately after transformation. This is only a transitory state because AF18 was found to be highly restricted in its lateral diffusion on the surface of adult parasites. In the larvae ofS. ratti, the change in affinity for AF18 was accompanied by the rapid shedding of an otherwise stable surface coat of polyanionic material, here visualized by labelling with fluorescein-conjugated cationized ferritin. Incubation of larvae in lipid-rich host serum during the induction of transformation inhibited subsequent labelling with AF 18. This possibly reflects competition for insertion sites and anin vivopropensity towards the acquisition of host lipid by invading parasites.
Eperythrozoon mariboi sp.nov., (Protophyta: Order Rickettsiales) a parasite of red blood cells of the flying fox Pteropus macrotis epularius in New Guinea
Authors: Ewers W. H.
Published: June 2009

Eperythrozoon mariboi sp.nov. is described from the red blood cells of splenectomized flying foxes (Pteropus macrotis epularius), from New Guinea. The parasite is polymorphic. The most common form is a fine line 5–8 μ long extending across the red blood cell. Marginal forms are also found. Multiple infections of the host cell also occur. In the initial infection ring forms were common, as well as other forms.

Parasitaemia was followed by anaemia, and the infections were characterised by repeated relapses at irregular intervals.

This work was supported by Grant No A1–08449 from the National Institutes of Health, United States Department of Health, Education and Welfare. I would like to thank Mr T. Ikupu and Mr T. Engendi, both of the University of Papua and New Guinea, for technical assistance; Mrs M. Cahill, also of the University of Papua and New Guinea for attempting to culture the organisms; Dr D. Weinman of Yale University, for confirming the identity of the parasites; Dr T. J. Dondero of the Hooper Foundation for translating some of the references into English; and Dr F. Colley also of the Hooper Foundation, for comments on the manuscript.

The analysis of some of the data in this paper was done while I was on study leave at the Institute for Medical Research, Kuala Lumpur, and I would like to thank its Director for the hospitality provided.

I would especially like to thank Mr Yap Loy Fong, Institute for Medical Research, Kuala Lumpur, for preparing Fig. 1.
Studies on the sex ratio of worms in schistosome infections
Authors: Mitchell G. F. , Garcia E. G. , Wood S. M. , Diasanta R. , Almonte R. , Calica E. , Davern K. M. , Tiu W. U.
Published: June 2009

Sex ratios of adult schistosomes in mice are almost invariably different from 1·0 and are biased towards males. The bias applies to wild rats infected withSchistosoma japonicumand trapped in an endemic area of the Philippines (male: female ratio = 1·7). It also applies to cercariae of snails collected in such areas and assessed by infection of laboratory mice using cercariae from individual snails (male: female ratio may approach 6·0). Experiments were designed to determine if duration of infection in the mammalian host was a factor that influenced the sex ratio of miracidia used for infecting snails and subsequently mice. BALB/c and C57BL/6 mice were infected with 100 cercariae ofS. mansoni, and liver eggs harvested at early and late time points for infection of snails and production of cercariae. Two phenomena were demonstrated: firstly, a more pronounced male bias when eggs were harvested late compared with early in infection; secondly, a reduced apparent hatchability of eggs in BALB/c compared with C57BL/6 livers. The possibility is raised by the data that female miracidia within eggs of chronically infected individuals may be more prone to immune damage than male miracidia with important epidemiological consequences.
Proteolytic activity inTritrichomonas mobilensis
Authors: Bózner P. , Demeš P. , Štefanovič J.
Published: June 2009

Cell extracts of an entero-invasive protozoon of squirrel monkeys,Tritrichomonas mobilensis, contained relatively high proteolytic activity, measured on hide powder azure (HPA). Multiple proteinase forms, optimally active at pH 5–7, were detected by electrophoretic analysis in gelatin-containing polyacrylamide gels. Three major proteinase bands of apparent low molecular weights,Mr18, 23 and 30 kDa, were seen on gels. Inhibition-activation studies suggest that only cysteine proteinases were involved in HPAase and gelatinolytic activities ofT. mobilensiscell extracts.
Trichobilharzia ocellata: chemical stimuli of duck skin for cercarial attachment
Authors: Feiler W. , Haas W.
Published: June 2009

Trichobilharzia ocellatacercariae attach readily to the foot skin of their duck host, but poorly to preen-gland contents. The attachment to duck foot disappears when the skin surface lipids are extracted, and can be restored by reapplication of the lipids to the skin. Hydrophilic skin extracts are without any effect. Thin-layer chromatographic fractionation of duck-foot skin surface lipids reveals cholesterol and ceramides as attachment stimuli. A stimulation of cercarial attachment by these hydrophobic host signals is supported by the host identification pattern of the cercariae, which secures a close contact with encountered substrates.
Breakdown of the blood-brain barrier in murine cerebral malaria
Authors: Thumwood C. M. , Hunt N. H. , Clark I. A. , Cowden W. B.
Published: June 2009

Cerebral malaria in A/J and CBA/H mice infected withPlasmodium bergheiANKA is accompanied by mononuclear cell infiltration, haemorrhage and cerebral endothelial cell damage. This damage is presumably one of the causes of the breakdown of the blood—brain barrier which was detected by measuring the movement of the dye Evans blue and radioisotope labelled albumin and erythrocytes. The density of brain tissue, measured by a Percoll gradient technique, was significantly reduced in mice exhibiting cerebral symptoms, suggesting the occurrence of cerebral oedema.
Random mating in a natural population of the malaria parasitePlasmodium falciparum
Authors: Babiker H. A. , Ranford-Cartwright L. C. , Currie D. , Charlwood J. D. , Billingsley P. , Teuscher T. , Walliker D.
Published: June 2009

The genetic structure of a population of the malaria parasitePlasmodium falciparumhas been examined in a village in Tanzania. Seventeen alleles of the merozoite surface protein MSP-1 and 23 of MSP-2 were detected by the polymerase chain reaction (PCR) among the blood parasites of the inhabitants. Most infections contained mixtures of genetically distinct parasite clones. PCR was then used to examine individualP. falciparumoocysts, the products of fertilization events, in wild-caught mosquitoes. Forty-five out of 71 oocysts were heterozygous for one or both genes, showing that crossing between clones was taking place frequently, following uptake of mixtures of gametocytes by the mosquitoes. The frequency of heterozygous forms showed that random mating events probably occurred within mosquito bloodmeals between gametes belonging to different parasite clones.
Trypanosoma (Nannomonas) godfreyi sp. nov. from tsetse flies in The Gambia: biological and biochemical characterization
Authors: McNamara J. J. , Mohammed G. , Gibson W. C.
Published: June 2009

We provide evidence from isoenzyme analysis, hybridization with repetitive DNA probes, behavioural studies and morphometrics that 4 trypanosome isolates from Glossina morsitans submorsitans in The Gambia constitute a new species now named Trypanosoma (Nannomonas) godfreyi. The bloodstream trypomastigotes of T. (N.) godfreyi are relatively small with a mean length of 13·7 μm (range: 9·1–21·8 μm) and a mean width of 1·65 μm (range: 0·65–2·69 μm). There is no free flagellum and the marginal kinetoplast is subterminal to a rounded posterior end; the undulating membrane is usually conspicuous. As with other Nannomonas, T. godfreyi developed in the midgut and proboscis of Glossina and infections matured in 21–28 days in laboratory G. m. morsitans. In The Gambia the normal vertebrate host appears to be the warthog, Phacochoerus aethiopicus, although elsewhere other wild and domestic suids may also be implicated in the life-cycle. T. godfreyi was identified unequivocally using a 380 bp DNA probe specific for a major genomic repeat sequence; its isoenzyme profile distinguished it clearly from T. simiae and three strain groups of T. congolense: savannah, riverine-forest and kilifi.
Polymerase chain reaction detection ofTrypanosoma cruziin human blood samples as a tool for diagnosis and treatment evaluation
Authors: Britto C. , Cardoso M. A. , Vanni C. M. Monteiro , Hasslocher-Moreno A. , Xavier S. S. , Oelemann W. , Santoro A. , Pirmez C. , Morel C. M. , Wincker P.
Published: June 2009

Trypanosoma cruzispecific sequences were amplified by the polymerase chain reaction from total blood of human chagasic patients and normal individuals. A 330 bp fragment originating from kinetoplast DNA was specifically detected in most chagasic individuals. We tested the sensitivity and specificity of this method in normal and affected individuals attending the Evandro Chagas Hospital, Rio de Janeiro. The results of these tests were compared with serological diagnosis performed using standard techniques, and in some cases with xenodiagnosis. We found that none of the serologically negative individuals gave any specific amplification product, whereas 55 out of 61 patients previously serodiagnosed as chagasic were positive using the PCR method (sensitivity: 90%). Xenodiagnosis, which is currently considered to be the most sensitive parasitological technique for Chagas' disease diagnosis, detected only 12 out of 28 serologically positive patients (sensitivity: 43%). The usefulness of the PCR method was further investigated with chagasic patients who had received anti-parasite treatment with benznidazole. It has always been difficult to evaluate the incidence of cure in such cases by serology, since a humoral response againstT. cruziantigens may remain for years even in the absence of the parasite. We observed a positive amplification result in only 9 out of 32 treated patients who remained reactive when tested using classical serology. These observations suggest that PCR is the most sensitive technique available for direct detection ofT. cruziin chagasic patients and that it can be a very useful instrument for the follow-up of patients after specific treatment.
Localization of Diploptera punctata allatostatin-like immunoreactivity in helminths: an immunocytochemical study
Authors: Smart D. , Johnston C. F. , Maule A. G. , Halton D. W. , Hrcková G. , Shaw C. , Buchanan K. D.
Published: June 2009

The nervous systems of helminths are predominantly peptidergic in nature, although it is likely that the full range of regulatory peptides used by these organisms has yet to be elucidated. Attempts to identify novel helminth neuropeptides are being made using immunocytochemistry with antisera raised against peptides isolated originally from insects. One of these antisera was raised against allatostatin III, a peptide isolated originally from the cockroach, Diploptera punctata, and a member of a family of related peptides found in insects. Allatostatin immunoreactivity was found throughout the nervous systems of Mesocestoides corti tetrathyridia, and adult Moniezia expansa, Diclidophora merlangi, Fasciola hepatica, Schistosoma mansoni, Ascaris suum and Panagrellus redivivus. Immunostaining was observed in the nerve cords and anterior ganglia of all the helminths. It was also apparent in the subtegumental nerves and around the reproductive apparatus of the flatworms, in neurones in the pharynx of D. merlangi, F. hepatica, A. suum and P. redivivus, and in fibres innervating the anterior sense organs in the nematodes. Immunostaining in all species was both reproducible and specific in that it could be abolished by pre-absorption of the antiserum with allatostatins I–IV. These results suggest that molecules related to the D. punctata allatostatins are important components in the nervous systems of a number of helminth parasites, and a free-living nematode. Their distribution within the nervous system suggests they function as neurotransmitters/neuromodulators with roles in locomotion, feeding, reproduction and sensory perception.
Inhibition of malarial invasion by intracellular antibodies against intrinsic membrane proteins in the red cell
Authors: Dluzewski A. R. , Rangachari K. , Tanner M. J. A. , Anstee D. J. , Wilson R. J. M. , Gratzer W. B.
Published: June 2009

It has previously been shown that antibodies against the transmembrane proteins, band 3 and glycophorin A, inhibit entry of the merozoite into the red cell and, in the case of band 3, it was established that attachment of the parasite to the cell is not prevented. We have found that antibodies against the cytoplasmic domains of band 3 and of glycophorin A, when present in the interior of resealed ghosts of human red cells, also inhibit invasion byP. falciparum. It is inferred that attachment of the merozoite to the red cell causes structural effects that are transduced to the membrane cytoskeleton and the antibodies against transmembrane proteins interfere with the invasion sequence at this level.
Increased oviposition and growth in immature Biomphalaria glabrata after exposure to Schistosoma mansoni
Authors: Thornhill Joyce A. , Jones Janet T. , Kusel J. R.
Published: June 2009

Biomphalaria glabrata snails are known to be castrated by infection with the trematode parasite Schistosoma mansoni 4–6 weeks post-infection. The pattern of oviposition in the first 35 days post-exposure (p.e.) was investigated, in snails aged 14 weeks and measuring 7–10 mm diameter which had not commenced egg-laying, by counting the numbers of eggs laid in 7-day intervals. A group of exposed snails was compared with a control non-exposed group. The exposed group included both parasitized and non-parasitized snails, and showed a significant increase in the median number of eggs laid during the periods 14–21 and 22–28 days p.e. Throughout the entire 35-day period exposed non-parasitized snails laid significantly more eggs than control snails, while parasitized snails laid significantly more eggs than controls during days 22–28 p.e. and significantly fewer during days 29–35 p.e. Parasitized snails also laid significantly more eggs/egg mass in the period 16–28 days p.e. than did control snails. Growth of the snails was measured. By day 28 p.e. the mean diameter of the exposed group was significantly greater than that of the control group. The increase in oviposition by snails soon after exposure is discussed in terms of a compensatory response for expected future suppression of egg-laying. The fact that parasitized and non-parasitized snails both show increased oviposition indicates that normal development of the parasite is not necessary to trigger the response.
The aggregation response of Trichostrongylus colubriformis: a basis for the rapid interpretation of in vitro anthelmintic screens
Authors: Jenkins D. C. , Rapson E. B. , Topley P.
Published: June 2009

An in vitro anthelmintic primary screen in which the effects of compounds on the aggregation response of newly moulted adult worms of Trichostrongylus colubriformis was monitored is described. Representatives of all the major classes of the anti-trichostrongyle anthelmintics all inhibited worm aggregation completely when present in the culture medium either at or at less than micromolar concentrations. The screen proved highly selective for these broad-spectrum agents, much higher concentrations of the narrower spectrum anthelmintics, active only against blood-sucking nematodes, trematodes and/or cestodes, having little or no effect on this response. This in vitro assay, based solely on the occurrence or absence of worm aggregation following the final moult in culture, proved very easy to interpret rapidly and accurately. It can be recommended therefore for the primary mass screening of synthetic compounds or natural products for intrinsic activity against the trichostrongylid helminths of ruminants.
Entomopathogenic nematode (Heterorhabditidae and Steinernematidae) spatial distribution in turfgrass
Authors: Campbell J. F. , Lewis E. , Yoder F. , Gaugler R.
Published: June 2009

Understanding the temporal and spatial distribution of entomopathogenic nematodes is essential for determining the role of these insect parasites in soil communities and ultimately for their use in suppression of pest insect populations. We measured the vertical and horizontal distribution of endemic populations of entomopathogenic nematodes (Steinernema carpocapsae and Heterorhabditis bacteriophord) in turfgrass. Vertical distribution was determined by taking soil cores every 3 h from 05.00 to 23.00 h, over 4 days, and dividing the cores into 8, 1 cm deep sections. Steinernema carpocapsae was recovered primarily near the soil surface: 50% of positive sections were recovered in the thatch or first 1 cm of soil. S. carpocapsae recovery was lower during the middle of the day and none were recovered in the upper section. H. bacteriophora was recovered uniformly throughout the top 8 cm of soil and its vertical distribution did not change over the course of the day. Horizontal distribution was measured as the number of nematodes recovered from cores taken from 12 randomly selected 0·3 × 0·8 m sections from within four 15·3 × 15·3 m plots. Samples were collected biweekly over a 9-month period. H. bacteriophora had a patchier distribution than S. carpocapsae and both nematode species had more patchy distributions then their potential hosts. Our results support the hypothesis that these two species of nematode utilize different foraging strategies; S. carpocapsae primarily a surface adapted ambusher and H. bacteriophora as a cruise forager.