bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure of zoosporulation in Perkinsus atlanticus (Apicomplexa: Perkinsea)
Authors: Azevedo C. , Corral L. , Cachola R. 
Published: June 2009

SUMMARYLight 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

SUMMARYMalaria 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

SUMMARYVesiculated 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

SUMMARYComparisons 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

SummaryThe 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

SummaryThe 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

SUMMARYTwo 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

SUMMARYTwenty-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

SUMMARYThe 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

SUMMARYAn 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

SUMMARYTsetse 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

SUMMARYThe 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

SUMMARYMacrophage-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

SUMMARYTo 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

SUMMARYHost 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.