bluuebunny/crossref_metadata_2025 huggingface dataset:
Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector
Authors: Basáñez M. G. , Remme J. H. F. , Alley E. S. , Bain O. , Shelley A. J. , Medley G. F. , Anderson R. M.
Published: June 2009

A previous paper reported that the intake ofOnchocerca volvulusmicrofilariae (mff) by different species ofSimuliumis essentially proportional to the parasite load in the skin of infected carriers. This paper examines the fate of the ingested mff in susceptible vectors to assess the relationship between parasite intake and infective larval output in blackfly species with and without well-developed cibarial armatures. Analysis is based on data from 3 onchocerciasis endemic areas: Guatemala (S. ochraceum s.l.), West Africa (S. damnosum s.l./S. sirbanum) and the Amazonian focus between South Venezuela and Northern Brazil (S. guianenseandS. oyapockense s.l.). The data, which include published and unedited information collected in the field, record experimental studies of parasite uptake by wild flies maintained in captivity until the completion of the extrinsic incubation period. The relationship between L3 output (measured as the mean number of successful larvae/fly or, as the proportion of flies with infective larvae) and average microfilarial intake, was strongly non-linear. This non-linearity was best represented by a sigmoid function in case of armed simuliids (S. ochraceum s.l., S. oyapockense s.l.), or by a hyperbolic expression in that of unarmed flies (S. damnosum s.l., S. guianense). These results are compatible, respectively, with the patterns of ‘initial facilitation’ and ‘limitation’ described in culicid vectors of lymphatic filariases. A maximum mean number of 1–3 L3/fly was observed in all 4 vectors. It is concluded thatO. volvuluslarval development to the infective stage is regulated by density-dependent mechanisms acting at the early phase of microfilarial migration out of the blackfly's bloodmeal. Damage by the bucco-pharyngeal armature may also be density dependent. A hypothesis, based on this density dependence is forwarded to explain initial facilitation, so far only recorded in vectors with well-developed cibarial teeth. Our results provide quantitative support for the conjecture that chemotherapy alone is likely to have a greater impact on reducing onchocerciasis transmission in endemic areas where the main vector has a toothed fore-gut than in foci where the vectors have unarmed cibaria.
The effect of the nematode peptides SDPNFLRFamide (PF1) and SADPNFLRFamide (PF2) on synaptic transmission in the parasitic nematodeAscaris suum
Authors: Holden-Dye L. , Franks C. J. , Williams R. G. , Walker R. J.
Published: June 2009

The action of two peptides isolated from the nematodePanagrellus redivivus, PF1 (SDPNFLRFamide) and PF2 (SADPNFLRFamide) have been studied on synaptic transmission in the motornervous system of the parasitic nematodeAscaris suum.Intracellular recordings were made fromAscarissomatic muscle cells and excitatory junction potentials (EJPs) elicited by stimulation of the ventral nerve cord. The EJPs were cholinergic as they were blocked by theAscarisnicotinic receptor antagonist, benzoquinonium. PF1 caused a slow hyperpolarization, similar to the action of this peptide first reported by Bowman, Geary & Thompson (1990) and further characterized by Frankset al.(1994). The hyper-polarization was accompanied by a marked decrease in the amplitude of the EJPs with an EC50of 311 ± 30 nM (n= 5). This inhibition is unlikely to be due to a post-synaptic site of action of the peptide as the muscle cell input conductance was not significantly altered by PF1 and furthermore the response to bath-applied acetylcholine was not inhibited by PF1 at concentrations up to 10μM (n= 6). PF2 also inhibited the EJPs in a similar manner to PF1. These studies indicate that both of the peptides isolated from the free-living nematodePanagrellus redivivushave biological activity in the parasitic nematodeAscaris suum. PF1 and PF2 have inhibitory actions in contrast to the predominantly excitatory actions of theAscarisendogenous peptides AF1 (KNEFIRFamide) and AF2 (KHEYLRFamide). The potent actions of thePanagrellusneuropeptides PF1 and PF2 inAscarissuggest that peptides with a similar or identical sequence may also occur inAscarisand have an inhibitory role in the motornervous system.
The dynamics of nematode infections of farmed ruminants
Authors: Roberts M. G. , Heesterbeek J. A. P.
Published: June 2009

In this paper the dynamics and control of nematode parasites of farmed ruminants are discussed via a qualitative analysis of a differential equation model. To achieve this a quantity, ‘the basic reproduction quotient’ (Q0), whose definition coincides with previous definitions ofR0for macroparasites, but extends to models with periodic time-varying transition rates between parasite stages or management interventions, is introduced. This quantity has the usual threshold property: ifQ0is less than one the parasite population cannot maintain itself in the host population, and in the long term becomes extinct; but ifQ0is greater than one the parasite can invade the host population. An alternative quantity,R(E), that is often easier to calculate is also introduced, and shown to have the same threshold property. The use of these two quantities in analysing models for the dynamics of nematodes in complex situations is then demonstrated, with reference to the dynamics of mixed parasite species in one host; the effects of breeding host animals for resistance to parasitism; and the development of parasite strains that are resistant to chemotherapy. Five examples are discussed using parameters for the dynamics of nematode infections in sheep, and some statements on control policies are derived.
Immunoglobulin-G binding proteins in the ixodid ticks, Rhipicephalus appendiculatus, Amblyomma variegatum and Ixodes hexagonus
Authors: Wang H. , Nuttall P. A.
Published: June 2009

A guinea-pig immunoglobulin-G linked agarose column was used to detect the immunoglobulin-G binding proteins (IGBP) in the ixodid ticks, Rhipicephalus appendiculatus, Amblyomma variegatum and Ixodes hexagonus. IGBPs were found in salivary gland extract (SGE) of the unfed ticks of all 3 species. The sizes of the IGBPs, as determined by SDS–polyacrylamide gel electrophoresis, differed between species. In R. appendiculatus 2 IGBP bands were detected in haemolymph collected from unfed females and males, and an additional 78 kDa IGBP was detected in haemolymph samples of male and female ticks that had fed for 6 days. Although there was no difference in the IGBP profile of SGE derived from unfed male and female R. appendiculatus, 2 new IGBPs were detected in the SGE of the male ticks after they had fed for 6 days. The possible function of IGBP in ticks is discussed.
An immunodominant antigen on theDictyocaulus viviparusL3 sheath surface coat and a related molecule in other strongylid nematodes
Authors: Gilleard J. S. , Duncan J. L. , Tait A.
Published: June 2009

Monoclonal antibody 2A6 binds to the surface of theDictyocaulus viviparusL3 sheath and identifies a molecule which is highly antigenic in both infected and vaccinated cattle. Immunogold electron microscopy reveals that the antibody binds to a highly stable surface coat overlying the epicuticle of the L3 sheath. The binding to the cuticular surface is stage specific, being restricted to the surface of the L3 sheath, although the antigen can be detected on Western blots of parasite homogenates from the L1 stage. Immunofluorescence on live parasites demonstrates that the antibodies also bind to the L3 sheath surface of many other strongylid nematodes. The antigen detected by 2A6 differs in molecular weight between the species; inD. viviparusthe antigen is poorly resolved between 29 and 40 kDa by SDS-PAGE whereas in nematodes from the family Trichostrongyloidea a single band or doublet of approximately 20 kDa is detected, suggesting that a related molecule is present in these species. Although infection and vaccination withD. viviparuselicits a strong immune response to the L3 sheath antigen this does not appear to be the case following infection with other strongylid nematodes.
Distribution of schistosome genetic diversity within molluscan intermediate hosts
Authors: Minchella D. J. , Sollenberger K. M. , Pereira De Souza C.
Published: June 2009

Naturally infected Biomphalaria glabrata snails were collected at two sites near Belo Horizonte, Brazil, and Schistosoma mansoni cercariae isolated from single snails were used to infect individual mice. Genetic comparison of single worm DNA was accomplished by hybridization of Southern blots to a polymorphic repetitive DNA element. Genetic profiles of parasite individuals revealed a diverse array of parasite genotypes in naturally infected intermediate hosts. The observed distribution of schistosome genotypes among intermediate hosts indicates that over half of the infected snails harbour multiple miracidia. Snails were more likely to carry multiple infections than expected by chance. This degree of overdispersion combined with high levels of genetic variability facilitates multi-genotype transmission and helps maintain parasite genetic diversity.
The anti-haemostatic strategies of the human hookwormNecator americanus
Authors: Furmidge B. A. , Horn L. A. , Pritchard D. I.
Published: June 2009

The human hookwormNecator americanusappears to have evolved a number of complementary strategies to overcome the host's haemostatic processes. These include the inhibition of blood coagulation, platelet aggregation and mediator release, and the secretion of fibrinogenolytic enzymes. These strategies presumably allow the parasite to establish the chronic infections so often documented in human populations.
Insect immunity: early events in the encapsulation process of parasitoid (Leptopilina boulardi) eggs in resistant and susceptible strains of Drosophila
Authors: Russo J. , Dupas S. , Frey F. , Carton Y. , Brehelin M.
Published: June 2009

Eggs of an immune suppressive strain ( = virulent) of the parasitoid Leptopilina boulardi are encapsulated neither in resistant nor in susceptible strains of Drosophila melanogaster but are encapsulated in Drosophila yakuba. Eggs of a non-immune suppressive strain ( = avirulent) of the same parasitoid are encapsulated in a resistant strain of D. melanogaster and in D. yakuba but are not encapsulated in a susceptible strain of D. melanogaster. Egg chorion in the 2 parasitoid strains showed the same morphology and the same modifications after egg laying whatever the host strain. When a capsule is built, a small dotted dense layer was first spread on the chorion, followed by accumulation layers of cells (plasmatocytes and lamellocytes) and lastly necrosis of the inner haemocytes. The encapsulated eggs darken only at the time of necrosis of haemocytes. In susceptible hosts, neither the tiny dense layer nor haemocyte accumulation occured. We concluded that (1) this tiny dense layer was present before the deposition of the first haemocytes, (2) inhibition of deposition of this dense layer was the initial event of the induced immunosupression, (3) haemocytes other than lamellocytes were engaged in caspsule formation, (4) the immunosupressive factors did not target only the lamellocytes but also the plasmatocytes, (5) darkening of the encapsulated eggs was due to cell necrosis rather than to extracellular melanin deposition.
Energy restriction and severe zinc deficiency influence growth, survival and reproduction ofHeligmosomoides polygyrus(Nematoda) during primary and challenge infections in mice
Authors: Shi H. N. , Scott M. E. , Koski K. G. , Boulay M. , Stevenson M. M.
Published: June 2009

The objectives of this study were (1) to determine the impact of severe zinc deficiency on the establishment, growth, survival and reproduction ofHeligmosomoides polygyrusin the laboratory mouse, during both primary and challenge infection protocols, and (2) to determine whether the observed effects resulted from zinc deficiencyper se, or from the accompanying energy restriction. Three diet groups were used: zinc-sufficient (Zn+: 60 mg zinc/kg diet), zinc-deficient (Zn·75 mg zinc/kg diet) and energy restricted (ER: 60 mg zinc/kg diet pair fed to Zn−mice). Neither Zn−nor ER influenced the establishment of the parasite during a primary infection. However, both significantly influenced the early development of the parasite. The proportion of adult worms recovered 9 days post-infection (p.i.) was highest in Zn−mice, intermediate in ER mice and lowest in +Zn+mice. Worms were also distributed more distally in the intestine of the Zn−mice and worm survival was highest in Zn−mice, intermediate in ER mice and lowest in Zn+mice at both 4 and 5 weeks p.i. Although the length of female worms was reduced in Zn−mice, neitherper capitafecundity nor egg viability was affected by zinc deficiency. Energy restriction, on the other hand, significantly reduced worm fecundity at 5 weeks post-primary infection, but had no effect on egg viability. Zinc concentration of adultH. polygyruswas similar among dietary groups. The effects of zinc deficiency and energy restriction were also investigated 4 and 5 weeks after a challenge infection. Whereas strong host resistance was evident in Zn+and ER mice, based on comparison of worm numbers between challenged mice and primary infection controls, no evidence of resistance was detected in Zn−mice. As in the primary infection, female worms were shorter in Zn−mice than in ER and Zn+mice, and energy restriction but not zinc deficiency significantly affectedper capitafecundity. However, in contrast to the primary infection, ER mice had elevated rather than reduced fecundity. This study demonstrates a complex interaction between H.polygyrusand zinc and energy restriction, and highlights the importance of controlling for reduced food intake in nutrition–infection studies.
Maximum-likelihood estimates of the mortality and migration rates of the infective larvae ofOstertagia ostertagiandCooperia oncophora
Authors: Grenfell B. T. , Smith G. , Anderson R. M.
Published: June 2009

We present an analysis of the survival and migration rates of the infective (L3) stages ofOslertagia ostertagiandCooperia oncophora. Although the majority of laboratory studies show that the survival of the L3stage depends upon temperature, moisture and the age of the larvae, a simple mathematical model of larval demography, in which their mortality and migration rates are held constant, provides as good agreement between observed and predicted larval counts as models in which these rate processes are made explicit functions of larval age and microclimate. Maximum-likelihood estimates of larval mortality rates in the faeces and on the herbage are 0·0284/day and 0·00887/day respectively. The average migration rate from faeces to herbage under temperate Northern European conditions is estimated as 0·00884/day. Finally, we discuss the probable scale of L3larval losses due to desiccation and lavage (active or passsive migration into the soil).
Cuticle production and ecdysis in larval marine ascaridoid nematodes in vitro
Authors: Mercer J. G. , Munn A. E. , Smith J. W. , Rees H. H.
Published: June 2009

Infective 3rd-stage larvae of three species of marine ascaridoid nematodes, Pseudoterranova (= Phocanema = Porrocaecum = Terranova) decipiens, Anisakis simplex and Phocascaris/Contracaecum sp. were cultured in vitro in 0·9% saline or Medium 199 at 37°C beneath an atmosphere of either air or 95% air:5% CO2 All three species responded to culture at 37°C by producing a new cuticle. The majority of P. decipiens completed ecdysis under all the culture conditions employed. Ecdysis in A. simplex was stimulated by a high concentration of CO2; this effect was particularly noticeable in saline cultures. Both A. simplex and Phocascaris/Contracaecum sp. developed more effectively in a nutrient medium than in saline.
Quinacrine-resistantGiardia duodenalis
Authors: Upcroft J. A. , Campbell R. W. , Upcroft P.
Published: June 2009

Quinacrine resistance has been induced in 3Giardia duodenalislaboratory stocks and 4 lines resistant to other drugs. The quinacrine-resistant lines were maintained in normally lethal levels of 5 µM quinacrine and some lines are viable in 20 µM levels of the drug. Fluorescence studies indicated that quinacrine was taken up by sensitive cells but was actively excluded from resistant trophozoites. The nuclei were not a site of drug accumulation and no specific fluorescence in the trophozoite could be attributed to any structure. Blebs of concentrated drug appeared prior to disintegration of the membrane of drug-sensitive trophozoites exposed to drug overnight. Parasite lines already resistant to furazolidone adapted more readily to quinacrine exposure than drug-sensitive stocks. This multiple drug resistant phenotype was not as marked with metronidazole-resistant lines.
Genetic heterogeneity in helminths — a reply
Authors: Anderson R. M. , May R. M. , Gupta S.
Published: June 2009

The previous paper in this issue Computer model of the maintenance and selection of genetic heterogeneity in polygamous helminths by Saul uses an individual-based computer simulation to explore aspects of the transmission and maintenance of genetic heterogeneity among polygamous intestinal helminths, both in the absence and in the presence of external selection pressures resulting from chemotherapy. Saul finds that, in the absence of any selective effects, genetic heterogeneity persists, contradicting the results presented by Anderson, May & Gupta (1989) that mating probability functions create density-dependent and frequency-dependent selective pressures against a rare allele, which eventually leads to its elimination.
The impact of ticks onBufo marinusfrom native habitats
Authors: Lampo M. , Bayliss P.
Published: June 2009

We analysed the patterns of tick distribution on 2274 adult toads from Venezuela and Brazil, to explore whether these ectoparasites have any impact on the survival ofBufo marinus. A maximum-likelihood analysis showed that aggregation levels of ticks decreased significantly with the mean intensity of infection. This decline could be attributed to a density-dependent reduction of ticks within toads, density-dependent tick-induced toad mortality and/or density-dependent tick-induced changes in toad susceptibility. However, the relationship between the rate of change in tick loads and tick burdens from recaptured toads indicated that neither the loss of ticks within toads nor the toad susceptibility to further infection were dependent upon tick burdens. Therefore, we can indirectly infer that density-dependent tick-induced toad mortality is responsible for the observed decline in aggregation levels with tick age and burdens. On the other hand, a significant negative relationship between tick burdens and the size-specific weight of toads suggested that ticks may also have a significant impact on the patterns of weight deposition of adult toads. This evidence suggests that these ectoparasites may play an important role in regulating the densities ofB. marinusin native habitats.
Ultrastructural localization of Sm28 GST protective antigen inSchistosoma mansoniadult worms
Authors: Liu J. L. , Fontaine J. , Capron A. , Grzych J. M.
Published: June 2009

The localization of the 28 kDaSchistosoma mansoniglutathione S-transferase (Sm28 GST) has been investigated using immunohistochemistry and electron microscopy and the results compared with previously published data. This study confirms the wide distribution of this antigen in the parasite. In male and female worms, Sm28 GST is localized in the tegument, the parenchyma, the oesophageal epithelium and in genital organs. Sm28 GST was clearly detected in germinal and sustentacular cells. The decrease of staining intensity during the differentiation of germinal cells suggests a down-regulated expression of the molecule. At the ultrastructural level, this antigen was abundant in nuclei and less present in the cytoplasm. The marked heterogeneity observed in the staining of individual worms indicates that Sm28 GST seems to be closely associated with the parasite’s metabolism. The results are discussed in relation to the biological and protective functions of the protein.
Characterization of intestinally active proteinases of cystnematodes
Authors: Lilley C. J. , Urwin P. E. , McPherson M. J. , Atkinson H. J.
Published: June 2009

Cryostat sections of juvenile and adult female stages of the soybean cyst-nematode,Heterodera glycines, were incubated with 4 different naphthylamide-linked peptide substrates to localize and characterize proteinase activity within the animal. Detected activity was restricted to the intestine and 2 distinct classes of proteinase were identified on the basis of substrate specificity and sensitivity to plant proteinase inhibitors. A cathepsin L-like cysteine proteinase activity capable of hydrolysing the synthetic substrates Z-Ala-Arg-Arg-MNA and Z-Phe-Arg-MNA but not Z-Arg-Arg-MNA or L-Arg-NA was inhibited by an engineered variant of a cysteine proteinase inhibitor from rice (Oc-IδD86). The cleavage of Z-Phe-Arg-MNA was sensitive to inhibition by a combination of Oc-IδD86 and cowpea trypsin inhibitor (CpTI). Degenerate oligonucleotide primers were used to amplify fragments of cysteine proteinase genes from 2 cyst-nematodes,H. glycinesandGlobodera pallida. Comparison of theH. glycinesfragment with known genes established highest homology to cathepsin L-like genes. In contrast, the amplifiedG. pallidafragment displayed greatest homology to cathepsin B-like genes fromCaenorhabditis elegans.
Do three-spined sticklebacks avoid consuming copepods, the first intermediate host ofSchistocephalus solidus? — an experimental analysis of behavioural resistance
Authors: Wedekind C. , Milinski M.
Published: June 2009

Many parasites that use intermediate hosts are transmitted to the next host through predation. If the next host's fitness is strongly reduced by the parasite, it is under selection either to recognize and avoid infected intermediate hosts or to exclude that prey species from its diet when alternative prey are available. We investigated the predator-prey interaction between laboratory bred three-spined sticklebacks (Gasterosteus aculeatus), the second intermediate host of the cestodeSchistocephalus solidus, from 2 parasitized and 1 unparasitized population, and different prey types: infected and uninfected copepods and size-matchedDaphniaas alternative prey. Copepods with infective procercoids were more active, had a lower swimming ability and were easier to catch than uninfected controls. The sticklebacks preferred moving copepods. Therefore parasitized copepods were preferentially attacked and consumed. There was no effect of the sticklebacks' parent population being parasitized or not. The sticklebacks switched fromDaphniato (uninfected) copepods in the course of a hunting sequence; this switch occurred earlier in smaller fish. With this strategy the fish maximized their feeding rate:Daphniawere easier to catch than copepods but increasingly difficult to swallow when the stomach was filling up especially for smaller fish. However, there was no indication that sticklebacks from infected populations either consumedDaphniarather than copepods or switched later in the hunting sequence to consuming copepods than fish from an uninfected population. Thus, sticklebacks did not avoid parasitized prey althoughS. solidususually has a high prevalence and causes a strong fitness reduction in its stickleback host.
Factors influencing development of free-living generations of Strongyloides stercoralis
Authors: Shiwaku K. , Chigusa Y. , Kadosaka T. , Kaneko K.
Published: June 2009

The effects of duration of infection and of temperature and nourishment in cultures on development of free-living generations of Strongyloides stercoralis were studied quantitatively. Rhabditiform larvae, 228–353 μm long, were collected from infected dogs with or without prednisolone treatment using the Baermann apparatus. Cultures were carried out by the filter paper test-tube method under the following conditions: incubation temperature 15–40°C and faecal dilution 1:0–1:16. Rhabditiform larvae developed predominantly to free-living females at incubation temperatures of 15–30°C and low faecal dilutions, but filariform larvae appeared mainly under extreme conditions such as high temperature. Recovery rates of filariform larvae were inversely related to those of females. It was remarkable that high temperature, but not low faecal dilution, affected development of filariform larvae. Although the appearance of free-living males was constant in various environmental conditions, the present study indicated an increase in free-living males with the duration of infection. Thus, it seems that free-living males are already fixed as male in the egg stage, and potential female rhabditiform larvae differentiate into free-living females or filariform larvae depending on environmental factors. There is no marked difference in the development of rhabditiform larvae into filariform larvae in either the immunosuppressed dog or the intact dog.
Pomphorhynchus laevis (Acanthocephala): elevation of haemolymph protein concentrations in the intermediate host, Gammarus pulex (Crustacea: Amphipoda)
Authors: Bentley C. R. , Hurd H.
Published: June 2009

Comparisons were made between the protein concentrations and protein profiles of uninfected Gammarus pulex and those infected with cystacanths of Pomphorhynchus laevis. Comparisons of the extractable haemolymph volumes from uninfected and infected G. pulex, when related to host tissue weight, showed that there was no difference in the host tissue/haemolymph volume ratio between infected and uninfected individuals. SDS-PAGE of haemolymph samples resolved 36 bands of protein, the major components being band 6(19 kDa) and 21(33 kDa). Densitometric analysis of haemolymph samples showed that infected gammarids had total protein concentrations elevated by 84%. The (88 kDa) subunit was identified as the monomer of the respiratory protein haemocyanin. This band was significantly elevated in infected individuals (one-way ANOVA P < 0.001); increasing from 30 to 45% of the total haemolymph proteins.
A note on Lagochilascaris from the cat in Argentina
Authors: Sprent J. F. A.
Published: June 2009

Specimens of nematodes from the stomach, oesophagus and trachea of the cat, previously reported and described by Led et al. (1968), were found to resemble L. major more closely than other species in the genus. In the shape of the interlabia and the number of pits on the surface of the eggs, they conformed to this species. Accordingly they were identified as L. major although they differed from L. major in the width of the lips in relation to the postlabial collar and their more slender appearance, especially in the tail region. This is the third report of L. major and extends the host range and geographical distribution of this species.
Histochemical observations on carbohydrates, lipids and enzymes in digenean parasites and host tissues of Bithynia tentaculata
Authors: Reader Trevor A. J.
Published: June 2009

Active digenean larvae in Bithynia tentaculata were found to utilize both host carbohydrates and lipids, and these were incorporated into the bodies of developing cercariae. Although rediae obtain most of their nutrients by direct ingestion, a decrease in the glycogen and neutral fat content of intact digestive gland cells of snails infected with rediae suggests that these larvae may also absorb nutrients through their body walls, like sporocysts. In sporocyst infections, host glycogen is believed to be hydrolysed to glucose and other monosaccharides by the host's own enzymes, possibly phosphatases, which have been stimulated to greater activity by the parasites. These simple sugars, due to their small size, can then be absorbed through the sporocyst body wall. Similarly, host fats are probably degraded to fatty acids, possibly by a parasite-secreted lipase, prior to absorption by the parasites. Encysted metacercariae do not appear to feed, but they do have severe pressure effects which disrupt some of the digestive gland tubules. Such tubules show an increase in their neutral fat content and a decrease in phosphatase activity. Aminopeptidase enzymes secreted by active digenean larvae may be responsible for some lysis of host cells, and may also be involved in the breakdown of lymph proteins to amino acids.

I am indebted to Dr F. R. Stranack for her supervision and guidance throughout this investigation, and to Dr G. Charles and Dr T. Jenkins for their continued help and advice. This study was carried out during the tenure of a research assistantship awarded by the governors of Portsmouth Polytechnic.
NO nerves in a tapeworm. NADPH-diaphorase histochemistry in adultHymenolepis diminuta
Authors: Gustafsson M. K. S. , Lindholm A. M. , Terenina N. B. , Reuter M.
Published: June 2009

The free radical nitric oxide (NO), which is synthesized by nitric oxide synthase (NOS), has recently been discovered to function as a neuronal messenger. The presence of NOS was detected in the nervous system of adultHymenolepis diminutawith NADPH-diaphorase (NADPH-d) histochemistry. The NADPH-d histochemical reaction is regarded as a selective marker for NOS in neuronal tissue. NADPH-d staining was observed in nerve fibres in the main and minor nerve cords and the transverse ring commissures, and in cell bodies in the brain commissure, along the main nerve cords, in the suckers and the rostellar sac. NADPH-d staining was also observed in the wall of the internal seminal vesicle and the genital atrium. The pattern of NADPH-d staining was compared with that of the 5-HT immunoreactive nervous elements. The NADPH-d staining reaction and the 5-HT immunoreactivity occur in separate sets of neurons. This is the first time the NADPH-d reaction has been demonstrated in the nervous system of a flatworm, indicating that NOS is present and that NO can be produced at this level of evolution.
Hepatic fibrosis and gene expression changes induced by praziquantel treatment during immune modulation ofSchistosoma japonicuminfection
Authors: Kresina T. F. , He Qing , Degli Esposti S. , Zern M. A.
Published: June 2009

In the present study fibrogenic gene expression was determined in murineSchistosoma japonicuminfection during the progression of immune modulation of infection and following chemotherapy during the course of immune modulation. Histomorphometric analysis of granuloma size and collagen deposition revealed peak granuloma size in acute infection (5 weeks) and peak hepatic collagen content at 16 weeks of infection. Peak Type I collagen gene expression was concomitant with TGF-β1 gene expression at 8–11 weeks. Chemotherapy during either acute (9 weeks) or chronic (24, 28 weeks) infection resulted in increased collagen deposition and increased gene expression of Type I collagen and TGF-β1. However, chemotherapy at 14–16 weeks resulted in decreased levels of TGF-β1 gene expression and essentially minimal change in Type I collagen deposition and gene expression. These data indicate that chemotherapy of schistosomiasis japonica does not reverse hepatic fibrogenesis when administered in acute infection – when granuloma size is maximal – or in chronic infection. However, a beneficial effect on hepatic fibrogenesis is seen when chemotherapy is administered at 14–16 weeks post-infection, a time of decreasing granuloma size and maximal hepatic collagen content. Thus the ability to reverse schistosomal-induced hepatic fibrogenesis by chemotherapy may depend on disease stage.
Parasitic isopods of the family Cymothoidae from south Indian fishes
Authors: Pillai N. Krishna
Published: June 2009

In the present paper seven species of cymothoid isopods parasitic on the marine fishes of the Kerala coast are described. A preliminary diagnosis of three of them was published earlier (Pillai, 1954). Full descriptions of all the species are given below. The larval stages described were in all cases taken from the brood pouch. The present work forms part of a thesis for which the author was awarded the Ph.D. Degree by the Kerala University.
A comparison between the helminth burdens of male and female brown trout, Salmo trutta L., from a natural population in the River Teify, West Wales
Authors: Thomas J. D.
Published: June 2009

Nine hundred and five brown trout were collected from the River Teify, West Wales, over a period of 12 months and their helminth infestations are considered in relation to the age and sex of the host and season.

Only one statistically significant difference could be detected between levels of infestation in male and female trout of 1 and 2 years of age.

When trout of 3 years of age and over were spawning or recovering from the effects of spawning there is a tendency for sexually mature females to be more heavily infested with some parasites than the males. During the season of growth and maturation of the gonads this trend was reversed or became less marked. In the case of fish that were not spent or spawning the statistically significant differences showed the males to be more heavily infested than the females.

The possible reasons for these variations are discussed with particular reference to the roles of ‘physiological’ and ‘behavioural’ or ecological resistance'.
Immunolocalization and characterization of the low molecular weight antigen (4–5 kDa) ofToxoplasma gondiithat elicits an early IgM response upon primary infection
Authors: Tomavo S. , Couvreur G. , Leriche M. A. , Sadak A. , Achbarou A. , Fortier B. , Dubremetz F.
Published: June 2009

A striking feature of toxoplasmic seroconversion is the prominent and early IgM response to a low molecular weight antigen of 4–5 kDa. Two different monoclonal antibodies directed against the 4–5 kDa antigen have been generated and used to characterize this molecule. Using these monoclonal antibodies, we could demonstrate the surface localization of the lowMrantigen by immunofluorescence and immuno-electron microscopy assays. By immunoblotting, we observed that one of the monoclonal antibodies was unable to recognize the 4–5 kDa antigen in tachyzoites propagated in cell culture, indicating an epitope variability betweenToxoplasma gondiitachyzoites grownin vivoandin vitro. We discuss the implications of this latter finding in the design of diagnostic reagents.
Host finding behaviour as a predictor of foraging strategy in entomopathogenic nematodes
Authors: Grewal P. S. , Lewis E. E. , Gaugler R. , Campbell J. F.
Published: June 2009

Foraging strategies of eight species of entomopathogenic nematodes were predicted from their response to host volatile cues and dispersal behaviour on 2-dimensional substrates. Positive directional response to chemical cues and similar distances travelled on smooth (agar) or nictation substrates (agar overlaid with sand grains) by Heterorhabditis bacterio-phora, Heterorhabditis megidis, Steinernema anomali, and Steinernema glaseri suggest their cruising approach to finding hosts. The absence of directional response and less distance travelled on nictation substrate, than on smooth agar by Steinernema carpocapsae and Steinernema scapterisci suggest their ambushing mode of foraging. Steinernema feltiae and Steinernema sp. responded directionally to host volatiles, but travelled less distance on the nictation substrate than on smooth agar; the two species also did not nictate. The cruiser species located hosts more effectively in the sand columns, whereas the ambushers were more effective at finding hosts on filter paper. Steinernema feltiae and Steinernema sp. performed equally on filter paper and in the sand column. We conclude that H. bacteriophora, H. megidis, S. anomali and S. glaseri cruise to find hosts, whereas S. carpocapsae and S. scapterisci ambush hosts. Steinernema feltiae and Steinernema sp. are intermediary in the search continuum sharing some characteristics of both ambush and cruise foragers.
The effects of parasitism by larval Digenea on the digestive gland of the intertidal prosobranch,Littorina saxatilis(Olivi) subsp.tenebrosa(Montagu)
Authors: James B. L.
Published: June 2009

The effects of parasitism by five species of larval Digenea on the digestive gland cells ofLittorina saxatilis(Olivi) subsp.tenebrosa(Montagu) were investigated by comparing histochemically stained cells in healthy, starved and parasitized animals.

Two distinct effects were apparent: (a) The germinal sacs compress the walls of the digestive gland tubules and block the lumen. Since food cannot pass this block, digestive gland cells behind undergo starvation autolysis. (b) In digestive gland tubules not cut off from their food supply, glucose, glycogen, glycoproteins and lipid food storage globules are reduced and there is a compensatory increase in the number of food vacuoles in the digestive cells; an increase in glucose but a decrease in glycogen in the visceral haemocoel; and an increase in the number of secretory cells, perhaps in order to eliminate the parasite's excretory products from the visceral haemocoel.
Observations on the Morphology and Life Cycle ofNeodiplostomum intermedium(Trematoda: Diplostomatidae)
Authors: Pearson J. C.
Published: June 2009

1.Neodiplostomum intermediumPearson is recorded from four new hosts; as an adult from the water rat,Hydromys chrysogasterGeoffroy, and as a metacercaria (diplostomulum), from tadpole and adult of an undescribed tree frog,Hylasp., tadpole of (Hyla latopalmata(Günther)Mixophyes fasciolatusGünther and frog of an unidentified leptodactylid.

2. The life cycle ofNeodiplostomum intermediumwas followed experimentally; the hosts were:Pettancylus assimilis(Petterd), a fresh-water limpet, as first intermediate host; tadpole ofHyla pearsoniCopland as second intermediate host;Hyla caerulea(Shaw) a tree frog, andHemisphaerodon gerrardiPeters, the pinktongued skink, as paratenic hosts; andRattus assimilis(Gould) and laboratory rats as definitive hosts.

3. Descriptions are given of the morphology of the miracidium, mother sporocyst, daughter sporocyst, cercaria, and diplostomulum, with special reference to the structure of the miracidium and of the cercarial tail.

4. Observations are given on the embryology of the miracidium, hatching of the egg, transformation of the miracidium into the mother sporocyst with special reference to the germinal cells, the route and manner of escape of cercariae from the snail host, the development of the diplostomulum with special reference to the reserve excretory system, and the movements of diplostomula during metamorphosis of the tadpole host.

5. The haploid chromosome number is ten, as determined from squashes of testes. One paratype and a series of experimental adults have been compared with and found different fromNeodiplostomum(Fibricola)sarcophilusn.comb. The orthography and formal proposing of the names of the species ofFibricolatransferred toNeodiplostomumby Pearson (1959b) are corrected.

The writer wishes to thank Dr M. J. Mackerras, Queensland Institute for Medical Research, for generously supplying water rats; Professor J. F. A. Sprent, University of Queensland Veterinary School, for his criticism of the manuscript; Mr K. Webber and his sons for their assistance in catching rats and for permission to collect snails, frogs and tadpoles from their streams; and Mr R. J. Ballantyne for technical assistance. This study was supported by a grant from the Rural Credits Fund of the Commonwealth Bank of Australia.
New species of Near Eastern agamid scale-mites (Acarina, Pterygosomidae) with notes on the developmental stages of Geckobia hemidactyli Law., 1936
Authors: Jack K. M.
Published: June 2009

The following new species are described:

Pterygosoma sinaita sp.nov. (♀, ♂ nymph) off Agama sinaita, A. mutabilis and A. inermis.

P. adramitana sp.nov. (♀, ♂) off A. adramitana.

P. mutabilis sp.nov. (♀, ♂ nymph) off A. mutabilis, A. pallida, A. jayakari and A. inermis.

P. singularis sp.nov. (♀) off A. colonorum.

P. caucasica sp.nov. (♀, ♂ deutonymph, protonymph and larva) off A. caucasica.

P. foliosetis sp.nov. (♀, nymph) off Charasia dorsalis.

Descriptions are also included of the hitherto unrecorded male, nymph and larva of Geckobia hemidactylus Lawrence, 1936, from Hemidactylus mercatorius Gray from Ascension Island.
Pathology in Antechinus stuartii (Marsupialia) due to Demodex sp.
Authors: Nutting William , Woolley Patricia
Published: June 2009

Pathological manifestations occasioned by mites of the genus Demodex are reported from Antechinus stuartii, a marsupial mouse. Derangements from single mite invasion of a hair follicle to massive nodule formation are detailed. In heavy infestations mites are found well distributed in the skin of the body with nodules limited, however, to the head, hind legs, around the base of the tail, the cloacal regions and, in females, just anterior to the pouch area.

Mites invade the hair follicle, where increase in their numbers leads to hypertrophy of the follicular epithelium which forms marked lobules surrounded by heavily vascularized connective tissue. It is thought that destruction of the lobule cells and penetration of the blood vessels due to increased mite numbers and activity leads to leucocytic infiltration with destruction of the mites and nodule deflation. In two instances of nodule deterioration a thickened skin plaque with markedly reduced mite populations remained in place of the nodule.

Gross symptoms of demodicidosis are occasionally marked in animals maintained in the laboratory but have not been found in specimens from the field. This suggests that environmental or dietary factors may be important in the onset of gross symptoms of demodicidosis.

This investigation was supported in part by a National Science Foundation (U.S.A.) grant (G-23321) and by a Commonwealth Scientific and an Industrial Research Organization (Australia) grant for marsupial research to the Zoology Department, A.N.U.

Dr Herman Beerman, Professor and Chairman, Department of Dermatology, Graduate School of Medicine, University of Pennsylvania, very kindly read and criticized our interpretation of the pathology. We are grateful for his help.

We would like to thank Margaret Dahlquist, Research Assistant, for her excellent technical assistance in the preparation of material for this report.
The age and sex of the host as factors affecting the host–parasite relationship of the third-stage larva of Amplicaecum robertsi Sprent & Mines, 1960, in the laboratory mouse
Authors: Dobson Colin
Published: June 2009

There was no difference between the worm burdens or the lengths of the worms recovered from sexually immature male and female mice infected with Amplicaecum robertsi.

In mice older than 70 days there were fewer larvae recovered from the female than the male host. The larvae were also longer in the male than in the female mouse.

The suckling mouse harboured fewer larvae than the weanling; the susceptibility of the mouse continued to increase with increasing age until the one-hundredth day in the males and the seventy-fifth day in the females. In animals older than this an age resistance was apparent. It is suggested that the much lower susceptibility of the suckling mouse is due to the small gut and villi size reducing the establishment of the larvae.

Worm growth also varied with host age, the longest larvae being recovered from the suckling mice and successively smaller worms from each older age group up to the seventy-fifth day, beyond which there was no significant change in worm growth with age of the host. There was no difference between the worm burdens and the lengths of the worms recovered from 90-day-old mice. The injection of testosterone had little or no effect on the host–parasite relationship of gonad-ectomized animals. Larvae from gonadectomized mice were significantly shorter than those from the intact hosts.
An electron microscope study of the tegument and associated structures of Proteocephalus pollanicoli
Authors: Threadgold L. T.
Published: June 2009

The tegument of Proteocephalus pollanicoli is organized at two levels. The external level is a syncytial layer of protoplasm composed of vesicles in a granular matrix. The surface of this level has microvillus-like structure, microtriches, with sharp electron dense tips and less dense bases. Pinocytotic vesicles, large vacuoles, and evaginations occur at the surface of the external level, whereas mitochondria and lipid droplets tend to be concentrated basally. The basal plasma membrane has in some places small invaginations and at others large evaginations forming protoplasmic tubes which connect the external and internal levels.

The internal level is composed of individual areas of dense, granular protoplasm, each of which has a nucleus. These areas, or cuticular cells, contain lipid droplets, mitochondria, short lengths of agranular endoplasmic reticulum and phospholipid bodies. Two cuticular cells lying close together may be joined by a protoplasmic bridge and thereby form a limited syncytium.

The morphology of the tegument of this proteocephalid is compared with that of the cyclophyllidean species and the function of the tegument in parasitic helminths is discussed.

I should like to acknowledge the technical assistance of Mr W. Ferguson and Mr A. Lyness. My thanks are also due to the Wellcome Trust for a grant to purchase the Akashi Transcope and ancillary equipment.
Differentiation of three species ofNeoaplectan(Nematoda: Rhabditida), grown axenically
Authors: Jackson George J.
Published: June 2009

Three species of the genusNeoaplectana, nematodes from insects, when grown axenically, could be differentiated consistently by morphological, cultivational and serological criteria.

All three species were cultivated for consecutive generations on solid media such as a rabbit kidney slice at the bottom of an enriched agar slant. In axenic cultures with various liquid media, including some which were chemically defined, the ensheathed larvae ofN. glaserimatured and produced offspring which in turn developed and reproduced;N. dutkii(‘DD-136’) larvae matured, but a new generation did not develop; the majority ofN. carpocapsaelarvae survived but did not mature. LivingN. glaseri, used as a source of antigens to detect homologous antibodies, gave fewer cross-reactions than preparations of sonicated and frozen worms, and fewer false negative reactions than used cultivation media.

Morphological differences between the three species in cultures are described.

This work was done at The Rockefeller Institute in the department of Dr William Trager, with the technical assistance of June I. Schloemer and, subsequently, Kristin L. Schmidtchen. Preliminary morphological descriptions were made in association with M. B. H. Chitwood of the U.S. Department of Agriculture's Beltsville Parasitological Laboratory in Maryland. The author and work were supported by grants from the U.S. National Institutes of Health, 5-K3-AI-9522 and AI-04842.