bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the function of the oxyurid egg-shell
Authors: Wharton D. A. 
Published: June 2009

SUMMARYThe egg-shell of Hammerschmidtiella diesingi and Aspiculuris tetraptera reduces the rate of water loss from the egg when exposed to desiccation. Staining of the enclosed larva by acid fuchsin and the collapse of eggs exposed to desiccation indicate that the permeability barrier is heat labile. This suggests that the lipid layer is the main permeability barrie of the shell. The complex structure of the uterine layers has a similar morphology to the respiratory structures of the chorion of some insect eggs. Reflections from the shell, the rate of embryonic development under various conditions and the penetration of lead ions indicate that the shell does not trap a layer of air when immersed in water and the uterine layers cannot, therefore, function as a plastron network. Calculations indicate that if diffusion is limited to the pores in the external uterine layer, the area available for gaseous exchange is reduced by 85·5% in H. diesingi, 95·6% in A. tetraptera and 96·8% in Syphacia obvelata. It is suggested that the uterine layers of oxyurid egg-shells function in a similar fashion to the pores in bird egg-shells and the aeropyles in the chorion of insect egg-shells which do not possess plastron networks. These structures reduce water loss from the egg whilst ensuring an adequate supply of oxygen for embryonic development.
Reproductive potential of Gyrodactylus bullatarudis (Monogenea) on guppies (Poecilia reticulata)
Authors: Scott Marilyn E. 
Published: June 2009

SUMMARYTwo simple experiments were undertaken using the viviparous ectoparasite, Gyrodactylus bullatarudis, and laboratory-reared guppies, Poecilia reticulata, whereby detailed records of the number and temporal sequence of all births and the age at death were obtained for flukes on isolated guppies. Gyrodactylus bullatarudis has an average fecundity of 1·68 offspring during its expected life-span of 4·20 days. The instantaneous birth rate is independent of generation but dependent on age. The first offspring is born approximately 1 day after the birth of the parent and subsequent offspring are born at 2–2·5 day intervals. The average instantancous birth rate (under given experimental conditions) is 0.43/parasite/day. The death rate increases exponentially with the age of the fluke and has an average value of 0.24/parasite/day. A simple deterministic model incorporating age structure and an age-dependent death rate was found to provide a good fit to the observed exponential increase in G. bullatarudis numbers. The variability observed in this host–parasite system was found to be largely a function of chance, as shown by Monte Carlo simulations of stochastic birth–death processes.
The specificity of purine base and nucleoside uptake in promastigotes ofLeishmania braziliensis panamensis
Authors: Hansen B. D. , Perez-Arbelo J. , Walkony J. F. , Hendricks L. D. 
Published: June 2009

SUMMARYPromastigotes ofLeishmania braziliensis panamensisabsorbed the purines adenine, hypoxanthine, adenosine and inosine by a combination of diffusion and mediated components. When the uptake rates for these substrates were corrected for diffusion and compared, the purine bases adenine and hypoxanthine were transported at a significantly slower rate than the purine nucleosides adenosine and inosine. Competitive interactions among those purines tested confirmed the presence of mediated and diffusion components and suggested that three transport loci may be operating (Fig. 6). The first transport locus, designated Locus 1, transported inosine, Locus 2, the purine bases hypoxanthine and adenine and Locus 3, adenosine. In addition, adenine and hypoxanthine inhibited the uptake of one another competitively. A comparison of Kivalues derived from double reciprocal plots of labelled hypoxanthine and adenine uptake in the presence of the unlabelled substrates as inhibitors suggested that adenine has a greater affinity for the transport locus.
The influence of Hymenolepis diminuta on the survival and fecundity of the intermediate host, Tribolium confusum
Authors: Keymer Anne E. 
Published: June 2009

SUMMARYAn experimental study of the effects of parasitism by H. diminuta on the intermediate host, Tribolium confusum, is described. No density- dependent constraints on parasite establishment within individual hosts are evident, although a reduction in cysticercoid size at high parasite burdens is demonstrated. The relationship between parasite burden, host mortality and host fecundity is investigated. Host mortality is linearly related to parasite burden, whereas the relationship between parasite burden and host fecundity is non-linear. There is no difference in viability between eggs from infected and uninfected females. The generative causes of these effects are not investigated experimentally, although it is postulated that survival is related to the degree of damage to the midgut wall caused by parasite penetration, and fecundity to the biomass of parasites harboured by the host. The significance of these effects is discussed in relation to the overall dynamics of the host-parasite association.
Topography and Ultrastructure of the tegument of adultSchistosoma mekongi
Authors: Sobhon P. , Upatham E. S. , McLaren Diane J. 
Published: June 2009

SUMMARYThe tegument of adultSchistosoma mekongihas been studied by both scanning and transmission electron microscopy. The gross surface topography of the parasite resembles that ofS. japonicum, in that branched ridges, microvilli and sensory papillae predominate; such characteristics distinguish these two species from the non-oriental schistosomes. A unique feature ofS. mekongi, however, is the numerous pleomorphic protruberances which are concentrated particularly on the middle three-fourths of the body surface. Transmission electron microscopy has revealed that these protruberances enclose bundles of microfilaments which appear to insert into the tegumental outer membrane. The microfilaments are suggested to have a supportive or stabilizing function, and may compensate for the absence of more typical crystalline spines. The tegumental outer membrane is typically heptalaminate in section, while the basal membrane infoldings are surrounded by concentrations of mitochondria. Three types of tegumental inclusion bodies have been recognized. Discoid bodies and membraneous bodies are morphologically identical to those described in all other schistosome species, except that the latter inclusions have been seen connected to each other and to the tegumental outer membrane by unique channels lined with trilaminate membrane. The third inclusion takes the form of spherical, lucent vesicles containing membrane fragments; these may represent the remains of spent membraneous bodies.
Running responses ofTrichinella spiralis-infected CD-1 mice
Authors: Rau M. E. , Putter L. 
Published: June 2009

SUMMARYMale CD-1 mice inoculated by gavage with 400 larvae ofTrichinella spiralisexhibited an increased latency of the wall-seeking response as well as a decline in running speed and the distance travelled to the first stop when compared with normal controls or animals inoculated with only 100 larvae. Doses of 200 larvae of this parasite affected running speed and distance travelled but not the advent of the running response. Such changes in behaviour may reduce the competitive fitness of the host and render it more susceptible to predation.
Pairing and aggregation of Amblosoma suwaense (Trematoda: Brachylaimidae) metacercariae in vitro and partial characterization of lipids involved in chemo-attraction
Authors: Fried B. , Robinson G. A. 
Published: June 2009

SUMMARYHistochemical and thin-layer chromatographic (t.l.c.) analyses were made on neutral lipids in the free (unencysted) metacercariae of Amblosoma suwaense (Brachylaimidae). As determined by t.l.c. the major neutral lipid fractions in metacercariae removed directly from Campeloma decisum snails were free sterols and sterol esters. Metacercariae incubated for 1 h at 37±1° C in sterile Locke's solution released mainly sterol esters and a lesser amount of free sterols into the medium. As determined by Oil Red O (ORO) staining, metacercariae accumulated neutral lipid in the intestinal caeca during incubation and the excretory system was ORO negative. Behavioural studies showed that metacereariae paired and aggregated in vitro and were attracted to lipophilic but not to hydrophilic worm products. Following t.l.c. preparative analysis it was demonstrated that metacercariae were attracted to sterol ester worm products but not to free sterol products.
Genes within the major histocompatibility complex of the guinea pig influence susceptibility toTrichostrongylus colubriformisinfection
Authors: Geczy A. F. , Rothwell T. L. W. 
Published: June 2009

SUMMARYThe influence of genes in the major histocompatibility complex (MHC) of the guinea pig on the susceptibility to infection with the parasitic nematodeTrichostrongylus colubriformiswas investigated. Back-cross analysis of 2 lines of guinea pigs suggests that genes that map in or near the I region of the guinea pig MHC influence susceptibility to infection by the parasite. However, other genes, possibily not linked to the guinea pig MHC, may also be required for the full expression of susceptibility.
Lernaeocera lusci(Copepoda: Pennellidae) on bib (Trisopterus luscus) from Southampton Water
Authors: Evans N. A. , Whitfield P. J. , Bamber R. N. , Espin P. M. 
Published: June 2009

SUMMARYO-group bib,Trisopterus luscuscaught on the cooling water intake screens of Fawley Power Station in March and April 1982 were infected (prevalence = 34·8%; intensity = 1·65/infected fish) with adult females of the pennellid parasitic copepodLernaeocera lusci. The bib sample of 293 fish was divided, for analysis, into 5 length classes. In each of these the level of parasitization withL. lusciwas broadly similar and in all 5 classes the parasite population was over-dispersed. Of the living copepods onT. luscus, 93% possessed egg strings while the remaining 7% consisted of earlier developmental stages. The majority of the parasites were attached to gill arches and here they exhibited distinct microhabitat and orientation preferences. A 3–2–4–1 descending order of gill arch utilization was apparent and copepods were non-randomly distributed along the dorso-ventral axis of gill arches with medial and ventral sectors being more heavily used than dorsal ones. An analysis was carried out on the body and egg string wet weights of parasites removed from fish harbouring different parasite densities. As copepod density increased neither the mean parasite body weight nor egg string weight altered significantly. Length/weight relationships of uninfected and infected fish were remarkably similar and thus provided no evidence thatL. luscihas a marked effect on the condition of O-groupT. luscus. The study demonstrated a significant positive association between infection withL. lusciand heavy infections with metacercarial cysts ofCryptocotyle lingua.
Fasciola hepatica in vitro: increased susceptibility to fasciolicides in a defined serum-free medium
Authors: Jenkins D. C. , Topley P. , Rapson E. B. 
Published: June 2009

SUMMARYThe cidal properties of some phenolic, halogenated diphenyl, salicylanilide, benzimidazole and diaminophenoxyalkane anthelmintics, against 6-week-old worms of Fasciola hepatica were assessed in vitro. In a conventional fluke culture medium containing RPMI 1640, supplemented with serum with or without rabbit erythrocytes or pink-ghosts, only the halogenated diphenyl and salicylanilide compounds showed activity at concentrations equal to or less than 100 μm. However, when basal, serum and cell-free RPMI 1640 was used, all compounds other than diamphenethide were highly active, their minimum lethal concentrations being some 25–125 times lower under these conditions. The inclusion of rabbit liver microsomes in the basal culture medium resulted in diamphenethide exhibiting cidal activity equivalent to that seen when its free-amine active metabolite was assayed. The possibility that the activity of many of these compounds was masked in vitro because of their serum binding properties is discussed. Recommendations are made that in vitro screens for new fasciolicides should be carried out in serum-free medium and that additional replicates containing mammalian liver microsomes and liver cytosolic extracts be included as means for the metabolic activation of certain otherwise undetectable prodrugs.
Peptidase in the plasma of mice infected withTrypanosoma brucei brucei
Authors: Knowles G. , Black S. J. , Whitelaw D. D. 
Published: June 2009

SUMMARYThe plasma of mice infected with pleomorphicTrypanosoma brucei bruceicontains a peptidase which has the same electrophoretic mobility on starch gels as a parasite peptidase. An enzyme with this electrophoretic mobility was not detected in the plasma of uninfected mice. The molecular weight of this enzyme in either parasite lysate or plasma from infected mice was approximately 40000 Da when assayed on a size exclusion column using high-performance liquid chromatography. The enzyme can cleave the dipeptides leu-ala, val-leu and pro-leu, but not the dipeptide phe-ala. The enzyme also cleaved the tripeptides tyr-tyr-tyr and leu-gly-gly. Another parasite peptidase which migrates on starch gels to a different position than the above-mentioned peptidase cleaved the dipeptides leu-ala, val-leu and pro-leu but could not cleave the tripeptides tyr-tyr-tyr or leu-gly-gly. Furthermore, incubation of this parasite peptidase with normal mouse plasma at 37 °C resulted in an apparent loss of detectable activity. It is postulated that the plasma of mice modifies either the charge or enzymic activity of this peptidase. We speculate that the parasite peptidase present in the plasma of mice infected withT. bruceicould contribute to pathogenesis.
Hatching and survival characteristics of Cyathocotyle bushiensis Khan 1962 (Digenea) eggs and miracidia
Authors: Ménard L. , Scott M. E. 
Published: June 2009

SUMMARYCyathocotyle bushiensis Khan 1962 is a digenean intestinal parasite of ducks that appears to be involved in seasonal mortality of the definitive host. Temperature dependence of egg hatching and miracidial survival at 25%C were experimentally investigated as part of a study on transmission of the larval stages. Maximum percentage of hatching was obtained at a temperature of 25%C, at which the average hatching time was 21·7 days. The average hatching time decreased linearly from 38·9 days to 9·8 days between 18 and 28%C. Eggs exposed to cold (4%C) prior to incubation at 25%C were significantly less successful in hatching than fresh eggs incubated at the same temperature. Their hatching percentage was much reduced and their average hatching time was increased. Similarly, eggs collected in late autumn (as opposed to summer) and incubated at 23%C had significantly lower hatching success and significantly increased average hatching time. At 25%C, the average life-span of the miracidia was 8·8 h. These results are compared with similar data from other digenean species and their significance is discussed in relation to transmission to the first intermediate host in climatic conditions prevalent in endemic areas.
A genetic comparison between natural and laboratory strains of Echinostoma (Trematoda) by isoenzymatic analysis
Authors: Voltz A. , Richard J. , Pesson B. 
Published: June 2009

SUMMARYA comparative isoenzyme study between a natural population of Echinostoma caproni and 2 strains of E. caproni and E. togoensis, maintained for a long time in the laboratory led to the following conclusions. (1) The natural E. caproni population showed polymorphism of associated PGM and GPI genotypes. Some zymograms were identical to those of experimental strains. Allelic frequencies show that the natural population is panmictic according to the Hardy-Weinberg equilibrium. (2) The laboratory strains were monomorphic, and interbreeding produced double-heterozygous F1 progeny, identical to those of the natural population.
Comparative study on the infection rates of differentGlossinaspecies for East and West AfricanTrypanosoma vivaxstocks
Authors: Moloo S. K. , Kutuza S. B. , Desai J. 
Published: June 2009

SUMMARYTeneral maleOlossina morsitans centralis, G. austeni, G. palpalis palpalis, G. p. gambiensis, G. fuscipes fuscipes, G. tachinoidesandG. brevipalpiswere fed on the flanks of Boran calves infected withTrypanosoma vivaxstock ILRAD 2241 isolated from a cow in Likoni, Kenya; stock ILRAD 2337 isolated from a cow in Galana, Kenya; stock ILRAD 1392 isolated from a cow in Nigeria; or, stock EATRO 1721 isolated fromG. m. submorsitansin Nigeria. The tsetse were fed on the infected hosts for 24 days and were then dissected to determine the infection rates. InG. m. centralisandG. brevipalpis, the mature infection rates ofT. vivaxfrom Kenya were 61·1 %, and 75·3% for ILRAD 2241, and 36·2% and 58·2% for ILRAD 2337, respectively. InG. austeniand in the fourpalpalisgroup of tsetse, the rates for these two stocks were very low and ranged from 0% inG. p. palpalisto 1·8% inG. austenifor ILRAD 2241 and from 0% inG. f. fuscipesto 5% inG. tachinoidesfor ILRAD 2337. In contrast, the hypopharyngeal infection rates ofT. vivaxfrom Nigeria were quite high in all the 7 tsetse species and sub-species. They ranged from 55·5% inG. austenito 919% inG. p. gambiensisfor ILRAD 1392, and from 71·4% inG. austeneito 97·1 % inG. brevipalpisfor EATRO 1721. It is suggested that successful establishment ofT. vivaxinfection in a particular tsetse species could depend on the biochemical characteristics of its attachment sites in the food canal and the efficiency of bloodstream trypomastigotes of a particularT. vivaxstock to attach to such sites and undergo complete development to meta-trypanosomes in the hypopharynx of the vector.
Modulation of the anti-phosphorylcholine immune response duringTrichinella spiralisinfections in mice
Authors: Ubeira F. M. , Leiro J. , Santamarina M. T. , Sanmartin-Duran M. L. 
Published: June 2009

SUMMARYThe nematodeTrichinella spiralisis able to modulate the antibody response, as measured by the plaque-forming cell (PFC) technique, to three thymus-dependent (TD) antigens: (1) a heterologous antigen unrelated to the parasite (sheep red blood cells (SRBC)); (2) an antigenic fraction, rich in phosphorylcholine (PC), obtained fromT. spiralis(FCpl) and (3) a heterologous antigen unrelated to the parasite, but sharing the PC epitope with the FCpl fraction (PC-KLH). During the life-cycle of the parasite in BCF1 mice, two opposing immunomodulating activities occur: (1) an immuno-potentiating activity in mice infected during the intestinal and larval migratory stages, for all three antigens, and (2) a carrier-specific immunosuppressive response in mice infected and immunized with the FCpl fraction during the muscle phase of the life-cycle. The anti-PC PFC response of these mice is dependent on the infection dose and decreases from day 35 post-infection (p.i.) until at least day 85 p.i.. The factor responsible for the stimulating effect observed during this stage is the presence of migratory larvae in the host. All the foregoing seems to indicate thatT. spiraliscan use specific suppression mechanisms to aid in its own survival.
Contributions of ascariasis to poor nutritional status in children from Chiriqui Province, Republic of Panama
Authors: Taren D. L. , Nesheim M. C. , Crompton D. W. T. , Holland Celia V. , Barbeau Irma , Rivera Gloria , Sanjur Diva , Tiffany Jean , Tucker Katherine 
Published: June 2009

SUMMARYRelationships between ascariasis and lactose digestion and between ascariasis and food transit time from mouth to caecum were investigated in young children from Chiriqui Province, Republic of Panama. The breath hydrogen method was used in both studies.Ascaris-infected children showed a significantly poorer degree of lactose digestion following a test oral load than uninfected children. Recovery of the capacity of the children to digest lactose was still not fully complete for at least 3 weeks following anthelmintic treatment. On average, the mouth-to-caecum transit time was similar in infected and uninfected children, but among theAscaris-infected children the transit time tended to be shorter in relation to the intensity of infection. Evidence from a cross-sectional survey indicated that ascariasis was significantly associated with reduced plasma vitamin A and carotenoid concentrations. This relationship remained after controlling for a range of socio-economic variables.Ascaris-infected children were frequently found to have lower haematocrits and blood haemoglobin concentrations than uninfected children, but these relationships could not be attributed to ascariasis alone.
The muscle, nervous and excretory systems of the plerocercoid of Callitetrarhynchus gracilis (Rud., 1819) (Pintner 1931) (Cestoda: Trypanorhyncha) from Bermuda fishes
Authors: Rees F. Gwendolen 
Published: June 2009

SummaryThe plerocercoid of Callitetrarhynchus gracilis was found in the body cavity of 14 species of fishes from Bermuda. The scolex, having completed its development, continues to grow within the blastocyst. The two mobile bothridia possess lateral grooves containing backwardly directed spines. Rapid evagination of the proboscides is effected by two layers of contra-rotating spiral muscles in the walls of the proboscis bulbs. The proboscis retractor is protected from constriction, during contraction of the bulbs, by a rigid ring at the junction of bulb and sheath. Nine series of extrinsic muscles anchor the proboscis sheaths to the body wall and a ladder-like series of dorsal, ventral and lateral muscles anchors the bulbs to one another. The bulbar nerves arise from the lateral nerve cords and are joined by a series of central ring commissures along the length of the bulbs. Uniciliate sensilla occur on the scolex and glandular cells in the peduncle.
Invasion of mature and immature erythrocytes of CBA/Ca mice by a cloned line of Plasmodium chabaudi chabaudi
Authors: Jarra W. , Brown K. N. 
Published: June 2009

SummaryDuring the early stages of the primary Plasmodium chabaudi chabaudi AS parasitaemia in CBA/Ca mice this parasite invaded normocytes, but as the parasitaemia developed increasing numbers of parasites were seen within reticulocytes. During and just after peak parasitaemia, as further parasite replication was controlled, the ‘crisis’ phase ensued, mice became increasingly anaemic and reticulocyte numbers were markedly increased. As the parasitaemia was resolved during crisis in excess of 25% of parasites had invaded reticulocytes. In phenylhydrazine-pretreated mice with artificially high reticulocyte levels and infected with P. c. chabaudi AS, normocyte/reticulocyte invasion occurred with equal frequency. No reduction in the infectivity of parasite populations developing in reticulocytes was observed.
Simulations of enhanced malaria transmission and host bias induced by modified vector blood location behaviour
Authors: Rossignol P. A. , Rossignol A. Mackay 
Published: June 2009

SummaryMonte Carlo simulations were developed to assess the potential impact of parasite pathology on vector salivary function as well as of host haemostasis on transmission. Assuming that a proportion of desisting vectors switch host following failure to locate blood, we demonstrate three possible consequences: (1) infected vectors contact more hosts than non-infected hosts, (2) non-infected vectors are biased to infected hosts, independently of attraction, and (3) an exponential relationship exists between parasite load and transmission. We discuss possible epidemiological implications.