bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic characterization ofToxoplasma gondiistrains by random amplified polymorphic DNA polymerase chain reaction
Authors: Guo Z. G. , Johnson A. M. 
Published: June 2009

SUMMARYThe technique of Random Amplified Polymorphic DNA (RAPD) PCR has been used to detect DNA polymorphisms amongToxoplasma gondiistrains. Seven arbitrary oligonucleotides (10-mer) were used as primers to amplify total genomic DNAs and significant genetic heterogeneity was detected among 11T gondiistrains with different virulence for mice. The polymorphisms observed allowed relationship dendrograms ofT. gondiistrains to be constructed by PHYLIP and PAUP analyses. The genetic relationships of theT. gondiistrains generated by 2 analyses using completely different assumptions were similar. Both analyses revealed 2 groups ofT. gondiistrains, one formed by the 6 virulent strains and the other formed by the 5 avirulent strains. This suggests that the genus Toxoplasma may actually contain 2 groups, correlated with their virulence, which have probably evolved independently following their initial separation. Significant polymorphisms were also detected between 2 different laboratory stocks of theT. gondiiRH strain.
Virulence and transmission modes of two microsporidia inDaphnia magna
Authors: Mangin K. L. , Lipsitch M. , Ebert D. 
Published: June 2009

SUMMARYTo understand the relationship between mode of transmission and virulence, we investigated 2 microsporidian parasites inDaphnia magnalaboratory populations.Pleistophora intestinalisis only transmitted horizontally, whileTuzetiasp. is transmitted vertically with high efficiency from mothers to parthenogenetic male and female offspring. We were not able to transmitTuzetiahorizontally in the laboratory.Tuzetiareduces host life-time reproductive success and host survival to a much greater extent than doesP. intestinalis.Tuzetia-infected hosts were rapidly outcompeted by uninfected hosts. We suspect thatTuzetiainfections may persist in natural populations by an as yet undiscovered horizontal transmission. It is possible that an alternate host species may be involved. We present a mathematical model to analyse the conditions for the persistence of a parasite with perfect vertical and an additional degree of horizontal transmission. We show that horizontal and vertical transmission contribute additively to a parasite's ability to invade and persist. Since the fitness contribution of horizontal transmission increases with population size, only very low transmission probabilities per host-to-host contact are necessary for the persistence of parasites occurring in large populations such as those commonly found forDaphnia. The detection of such low rates of horizontal transmission appears unlikely under laboratory conditions since the necessary number of host-to-host (or host-to-spore) contacts is not feasible. We review mechanisms that can maintain vertically transmitted parasites in nature.
Differential development and emission ofTheileria parvasporozoites from the salivary gland ofRhipicephalus appendiculatus
Authors: Shaw M. K. , Young A. S. 
Published: June 2009

SUMMARYThe initiation of feeding of infectedRhipicephalus appendiculatusadults induces the rapid development ofTheileria parvasporoblasts within the salivary gland acini leading to the production of numerous sporozoites which are inoculated into the mammalian host initiating infection. In this study the pattern of development, host cell specificity and emission ofT. parvasporozoites within the salivary glands of heavily infected, 4-day fed adultR. appendiculatusticks was examined. Infected acini were randomly distributed throughout the salivary gland. Sporozoite development within each gland was not synchronized and wide variation in the rate of parasite development, which correlated with the secretory activity of the individual acinus, was observed in all glands examined. Previous studies had shown thatT. parvadeveloped primarily in Type III ‘e’ cells. However, in heavily infected salivary glands sporogony and the emission of mature sporozoites also occurred in ‘c’ cells of Type II acini. Sporozoite emission from infected cells occurred by a process similar to apocrine secretion. The loss of the apical membrane of the infected cell allowed sporozoites free access to the lumen of the acinus and into the collecting ducts of the salivary gland. Sporozoite discharge was gradual since few parasites were found in the acinus valve or in the collecting ducts. Furthermore, the small size of the acinar valve aperature ensures that only small numbers of sporozoites can be released at any one time from an infected acinus.
The kinetics of maturation of trypanosome infections in tsetse
Authors: Dale C. , Welburn S. C. , Maudlin I. , Milligan P. J. M. 
Published: June 2009

SUMMARYEstimates of the time delay between the infective bloodmeal and maturation (incubation or maturation time) for 4 trypanosome stocks (2 Trypanozoon and 2 Trypanosoma congolense) show that maturation time in tsetse is not a parasite species-specific constant. The mean incubation time of a Trypanosoma brucei rhodesiense stock (EATRO 2340 – 18 days) was not significantly different from one T. congolense stock (SIKUDA88 – 15·5 days) but was significantly greater than another (1/148 FLY9 – 12·5 days). There was no significant difference in incubation times between male and female Glossina morsitans morsitans for any of the stocks but in both of the Trypanozoon stocks the proportion of female flies producing mature infections was significantly less than in males. However, estimates of gene frequency, assuming a model in which maturation is controlled by an X-linked recessive allele, gave inconsistent results indicating that maturation cannot be controlled by a single sex-linked gene. Maturation was shown to be a tsetse sex-dependent phenomenon in Trypanozoon but not in T. congolense infections. Incubation time was quite variable even for a single trypanosome stock (e.g. standard deviation of 5 days for one Trypanozoon stock); we discuss how this variability can affect disease transmission, and the interpretation of age-prevalence data.
Isolation of Fasciola hepatica haemoglobin
Authors: McGonigle S. , Dalton J. P. 
Published: June 2009

SUMMARYA haemoprotein released in vitro by adult Fasciola hepatica was purified by gel filtration chromatography on Sephacryl S-200 and ion-exchange chromatography on DEAE-Sepharose. The molecule, with an apparent molecular weight of > 200 kDa, contains a haem group and has absorption spectra characteristics similar to haemoglobins. N-terminal amino acid sequence analysis revealed no similarity between the F. hepatica haemoglobin and other vertebrate or invertebrate haemoglobins. Antibodies to the haemoglobin molecule can be detected in the sera of F. hepatica-infected bovines as early as 1 week after infection.
Temporal differences in praziquantel- and oxamniquine-induced tegumental damage to adult Schistosoma mansoni: implications for drug-antibody synergy
Authors: Fallon P. G. , Fookes R. E. , Wharton G. A. 
Published: June 2009

SUMMARYA temporal study of the effects on the tegument of Schistosoma mansoni adult worm following in vivo praziquantel and oxamniquine treatment was performed. Drug-induced damage to the tegument, exposure of surface antigens and attachment of host antibody occurred rapidly, within 1 h, following praziquantel treatment. Oxamniquine-treated worms required 4–8 days for these effects to be apparent. The 2 drugs differed in the degree and sites of damage on the worm surface. The administration of 2 different polyspecific rabbit sera with drug significantly increased the efficacy of praziquantel when administered with the drug, but not when given 6–9 days after drug treatment. In contrast, only 1 serum was synergistic with oxamniquine when administered with drug and both sera were synergistic when given 6–9 days after drug treatment. The effect of immune killing of drug-treated worms is discussed.
A high prevalence of mixed trypanosome infections in tsetse flies in Sinfra, Côte d'Ivoire, detected by DNA amplification
Authors: Masiga D. K. , McNamara J. J. , Laveissière C. , Truc P. , Gibson W. C. 
Published: June 2009

SUMMARYThe prevalence of various species and subgroups of trypanosomes in the Sinfra area of C⊚te d'Ivoire was determined using the polymerase chain reaction (PCR). Using this technique to amplify specific satellite DNA targets, it was possible to identify developmental-stage trypanosomes in the midguts and the proboscides of tsetse without expansion of parasite populations. The predominant tsetse species in the area wasGlossina palpalis, whileG. palliceraandG. nigrofuscawere also present. Microscopical examination of 811 non-teneral flies revealed an infection rate of 14% in midguts and/or proboscides. Three subgroups ofTrypanosoma congolense(Savannah, Forest & Kilifi),T. simiae,T.godfreyi, West AfricanT. vivaxandT. bruceissp. were identified using PCR.T. congolenseForest was the most abundant of theNannomonastrypanosomes. Approximately 40% of all infections were mixed, and there was a significantly higher prevalence of apparently matureT. bruceissp. trypanosomes than has previously been reported. The present study demonstrates that PCR facilitates the easy identification of mature trypanosome infections in tsetse, providing a reliable estimation of trypanosomiasis challenge.
Heat shock response ofTrichinella spiralisandT. pseudospiralis
Authors: Ko R. C. , Fan L. 
Published: June 2009

SUMMARYHeat shock proteins (HSPs) were documented for the first time in both somatic extracts and excretory/secretory (ES) products of the infective-stage larvae ofTrichinella spiralisandT. pseudospiralis. Larvae recovered from muscles of infected mice were heat shocked at 37, 40, 43 and 45 °C in RPMI 1640 medium containing L-[35S]methionine. Somatic extracts and ES products of heat-shocked worms were then analysed by SDS-PAGE, autoradiography and laser densitometry. Prominent bands of HSPs were observed at 43 °C which is the optimal heat shock temperature. The major HSPs in somatic extracts ofT. spiraliswere 20, 47, 50, 70, 80 and 86 kDa. When the temperature was increased from 37 to 43 °C, the greatest increase in absorbance was observed in HSPs 70 and 86.In vitrotranslation of mRNA in a nuclease-treated rabbit reticulocyte lysate system showed an increase in the synthesis of the 80 kDa protein. This suggests that the production of HSP 80 is regulated at the transcriptional level. The major HSPs in the ES products were 11, 45, 53 and 64 kDa. InT. pseudospiralis, the major HSPs in the somatic extracts were 20, 26, 31, 50, 53, 70, 80 and 86 kDa, and in the ES products, 11, 35, 37, 41 and 64 kDa.
Density-dependent sex ratio in Echinomermella matsi (Nematoda), a parasite of the sea urchin Strongylocentrotus droebachiensis
Authors: Stien A. , Halvorsen O. , Leinaas H. P. 
Published: June 2009

SUMMARYWe investigated the adult sex ratio in 70 infrapopulations of the nematode Echinomermella matsi, a parasite of the green sea urchin Strongylocentrotus droebachiensis. The adult sex ratio was skewed towards female dominance at low adult intensity and towards male dominance at high adult intensity. We hypothesize that this is due to differences between the sexes in development and mortality rates, or that female recruitment is density dependent. A model with differences between the sexes in developmental and mortality rates may develop the observed sex ratios if the female developmental and mortality rates are several times that of the males. A large difference in developmental rates between the sexes appears unreasonable because the developmental rate for both sexes is low, and the predicted low female life-expectancy is unlikely because the males appear to accumulate in infrapopulations as the females age. Density dependence of female numbers is, however, supported by a significantly lower female recruitment in infrapopulations with old females. We also find that the mean male length is negatively related to measures of crowding, thereby supporting the hypothesis that competition is of importance in E. matsi infrapopulations. A female bias at low intensities of infection, a density dependence in female recruitment and the taxonomic position of E. matsi indicate that sex may be environmentally determined in this nematode.
NADPH diaphorase activity in peptidergic neurones of the parasitic nematode, Ascaris suum
Authors: Bascal Z. A. , Montgomery A. , Holden-Dye L. , Williams R. G. , Thorndyke M. C. , Walker R. J. 
Published: June 2009

SUMMARYThe histochemical marker for nitric oxide synthase, NADPH diaphorase, is known to co-localize in mammalian neurones with various classical neurotransmitters and neuropeptides. The nervous system of the parasitic nematode Ascaris suum has previously been shown to contain both NADPH diaphorase activity and neuropeptide immunoreactivity. This study examined the possibility that NADPH diaphorase and neuropeptide immunoreactivity may co-exist in the same neurones. Two antisera were used, one raised to KYSALMFamide, a C-terminal synthetic analogue of SALMFamide 1 (GFNSALMFamide), and another that recognizes calcitonin-gene-related peptide (CGRP). We provide evidence that in a distinct subset of neurones in the ventral, dorsal and lateral ganglia NADPH diaphorase staining and SALMFamide- like immunoreactivity are co-localized, suggesting a possible role for nitric oxide in modulating neuropeptide activity in these regions. CGRP-like immunoreactivity was less widely distributed, and was not consistently co-localized with NADPH diaphorase.
An initial characterization of the proteolytic enzymes secreted by the adult stage of the human hookwormNecator americanus
Authors: Brown A. , Burleigh J. M. , Billett E. E. , Pritchard D. I. 
Published: June 2009

SUMMARYThe proteolytic activities present in adultNecator americanusexcretory–secretory products have been assessed using biologically relevant, naturally occurring substrates (haemoglobin and fibrinogen) and a number of synthetic fluorogenic and chromogenic substrates. One broad peak of activity was observed against haemoglobin in the pH range 5 to 7, with maximum activity at pH 6·6, while fibrinogenolytic activity was shown to be greater at pH 3·5. Inhibition studies against haemoglobin, fibrinogen and synthetic substrates using a battery of appropriate protease inhibitors indicated the presence of a mixture of aspartyl, cysteinyl and serine proteases. Metal ion (Ca2+, Zn2+and Fe2+) stimulation was demonstrated, with stimulation by Zn2+being the most marked. These results are discussed in the context of recent developments in the field of parasite proteolytic enzymes, where they have been suggested as targets for immuno- and chemotherapy.
Host-specific components of the reproductive success of Transversotrema patialense (Digenea: Transversotrematidae)
Authors: Whitfield P. J. , Anderson R. M. , Bundy D. A. P. 
Published: June 2009

SUMMARYUsing a range of infection techniques, the ability of cercariae of the ectoparasitic digenean Transversotrema patialense to infect 24 species of tropical freshwater fish is examined. Of the 24 species (from 11 families) it is possible to infect 21 (from 8 families) under laboratory conditions. Reproductive success (R) for T. patialense from the cercarial infection process to the production of viable eggs by adult flukes is estimated for infections on two fish hosts, the cyprinid Brwhydanio rerio and the characinid Cheirodon sp. in controlled laboratory conditions. To calculate R, separate estimations of parasite infectivity, survival, fecundity and egg viability were made on populations of both host species. The enhanced reproductive success (R) of T. patialense on Cheirodon sp. is the composite resultant of higher infectivity, lower mean expected adult fluke life-span and higher mean fecundity/surviving worm when compared with infections on B. rerio under identical experimental conditions. Different patterns of egg viability of the two hosts do not materially influence differential reproductive success. A variety of formal techniques for handling the interacting components of reproductive success are described. The relationship between these techniques and the concept of basic reproductive rate, R0 (Macdonald, 1957; Anderson, 1982) is assessed.
Cloning and expression of DiT33 fromDirofilaria immitis: a specific and early marker of heartworm infection
Authors: Hong X. Q. , Mejia J. Santiago , Kumar S. , Perler F. B. , Carlow C. K. S. 
Published: June 2009

SUMMARYDirofilaria immitisis an important filarial parasite of dogs and cats, and a useful model for human filariasis. Current diagnostic tests for heartworm infection in animals rely on the presence of fecund female worms (usually found 6·5 months post-infection or later) and therefore fail to detect pre-patent infections. Putative pepsin inhibitors from 2 filarial parasites of humans namelyOnchocerca volvulus(Ov33, Oc3.6, OvDSB) andBrugia malayi(Bm33), have been shown to be useful in diagnosis of onchocerciasis and lymphatic filariasis, respectively. Previous studies have suggested that a homologue exists inD. immitis(DiT33), which may have potential in diagnosis of heartworm infection. In this study, the isolation and characterization of a cDNA clone encoding DiT33 is described.‡ This cDNA contains 12 bases of the nematode-specific 22 nucleotide spliced leader sequence and encodes a 26·4 kDa-protein with a high level of similarity (87–89%) to other filarial members of the family. DJT33 was over-expressed inE. colias a fusion with the maltose-binding protein and serological analysis was performed using a panel of clinically defined dog sera. The findings of this study indicate that DiT33 is a promising antigen for the early detection ofD. immitisand may be a valuable tool in the control and management of heartworm infection.
The entry ofTheileria parvamerozoites into bovine erythrocytes occurs by a process similar to sporozoite invasion of lymphocytes
Authors: Shaw M. K. , Tilney L. G. 
Published: June 2009

SUMMARYThe entry ofTheileria parvamerozoites into bovine erythrocytesin vivois described and compared to sporozoite invasion of lymphocytes. Merozoites make initial contact with erythrocytes with any part of their surface and invasion of the host cell does not require the re-orientation of the apical end of the merozoite towards the surface of the erythrocyte. After the initial attachment the merozoite and host cell membranes form a continual close junction with the two apposed membranes separated by a 6–8 nm gap containing moderately dense material. The progressive circumferential ‘zippering’ of these closely apposed membranes leads to the movement of the parasite into the erythrocyte. The newly internalized merozoite which is completely surrounded by the erythrocyte plasma membrane escapes from this enclosing membrane by a process involving the discharge of at least the rhoptries; whether the merozoite also contain other types of secretory organelles (e.g. micronemes, microspheres or dense bodies) remains to be determined. Morphologically, the events involved in merozoite invasion of erythrocytes are almost identical to the process of sporozoite invasion of lymphocytes but differ significantly from the entry process of the invasive stages of other Apicomplexan parasites.
Characterization of fractionatedSchistosoma mansonisoluble adult worm antigens that elicit human cell proliferation and granuloma formationin vitro
Authors: Hirsch C. , Goes A. M. 
Published: June 2009

SUMMARYSoluble adult worm antigens (SWAP) ofSchistosoma mansoniwere fractionated by fast protein liquid chromatography (FPLC) system, using Q-Sepharose anion-exchange resin, in order to characterize antigenic fractions that may elicit cell responses in human schistosomiasis. SWAP fractions were eluted by 20 HIM Tris–HCl solution (pH 9·6) with an increasing gradient of 1 M NaCl. The FPLC system was able to resolve 6 fractions, enumerated I to VI, according to the NaCl gradient. The analysis of each fraction on SDS–PAGE showed that fractions I to IV were constituted by multiple protein bands withMrranging from 21 to > 200 kDa. Large amounts of nucleic acids were evidenced in fractions V and VI, as revealed by ethidium bromide staining of agarose electrophoresis gels. Using ELISA, it was shown that sera from chronic schistosomiasis patients contained antibodies that recognized antigens in practically all fractions. Studies were designed to investigate the capacity of these fractions to induce cell proliferation and granuloma formation. It was demonstrated that fraction III stimulated a significant proliferative response of peripheral blood mononuclear cells (PBMC) from chronic schistosomiasis patients. However, fraction III coupled to polyacrylamide beads induced small granuloma formationin vitro, whereas beads coated with fractions I, II and V were able to induce significant granuloma reactions.
The activity periods and life-cycle of the tick Ixodes uriae (Acari: Ixodidae) in relation to host breeding strategies
Authors: Barton T. R. , Harris M. P. , Wanless S. , Elston D. A. 
Published: June 2009

SUMMARYWe investigated the timing of seasonal activity of the seabird tick Ixodes uriae by examining engorgement rates of off-host ticks and the prevalence of infested common guillemots (Uria aalge) and kittiwakes (Rissa tridactyla) on the Isle of May, Scotland. More than 99% of I. uriae fed during the period late April to early August which coincided with the seabird breeding season. No ticks fed in the autumn and winter, and none over-wintered in the engorged state. Peak tick feeding activity was during the hosts' incubation period in May and early June, when over 70% of birds were parasitized. Few ticks were active when guillemot chicks were being brooded, or during the early part of kittiwake chick-rearing. Adult female tick feeding peaked in the first week of June, while nymphal and larval activity peaked in the third week of May. Adult female ticks fed later than nymphs on guillemots and larvae on both guillemots and kittiwakes; however, there was considerable temporal overlap in the feeding periods of the 3 stages on both hosts. All larvae and nymphs fed in May and early June, but up to 18% of adult females remained unengorged at this time, and probably deferred feeding by 1 year. A small proportion of individuals which fed as larvae in May appeared to feed again as nymphs in July of the same season, thereby shortening their life-cycle by 1 year. The duration of the life-cycle of I. uriae on the Isle of May is typically 3 years but varies from 2 to 4 years. Ticks feeding on guillemots did so significantly earlier than those feeding on kittiwakes, possibly because guillemots start breeding earlier in the year. Breeding of both guillemots and kittiwakes was later in 1994 than in 1993. This delayed the activity of all tick stages on kittiwakes and adult female ticks on guillemots, but did not affect the timing of activity of nymphs or larvae feeding on guillemots.