bluuebunny/crossref_metadata_2025_split huggingface dataset:
A calreticulin‐like molecule from the human hookworm Necator americanus interacts with C1q and the cytoplasmic signalling domains of some integrins
Authors: Kasper Grit , Brown Alan , Eberl Matthias , Vallar Laurent , Kieffer Nelly , Berry Colin , Girdwood Karen , Eggleton Paul , Quinnell Rupert , Pritchard David I. 
Published: March 2003

Calreticulin was recently identified as a hookworm Necator americanus allergen, implying secretion, and contact with cells of the immune system, or significant worm attrition in the tissues of the host. As human calreticulin has been shown to bind to and neutralize the haemolytic activity of the complement component C1q, and to be putatively involved in integrin‐mediated intracellular signalling events in platelets, it was of interest to determine whether a calreticulin from a successful nematode parasite of humans, with known immune modulatory and antihaemostatic properties, exhibited a capacity to interfere with complement activation and to interact with integrin domains associated with cell signalling in platelets and other leucocytes. We can now report that recombinant calreticulin failed to demonstrate significant calcium binding capacity, which is a hallmark of calreticulins in general and may indicate inappropriate folding following expression in a prokaryote. Nevertheless, recombinant calreticulin retained sufficient molecular architecture to bind to, and inhibit the haemolytic capacity of, human C1q. Furthermore, recombinant calreticulin reacted in surface plasmon resonance analysis (SPR) with peptides corresponding to cytoplasmic signalling domains of the integrins αIIb and α5, in a calcium independent manner. SPR was also used to ratify the specificity of a polyclonal antibody to hookworm calreticulin, which was then used to assess the stage specificity of expression of the native molecule (in comparison with reverse transcriptase‐polymerase chain reaction), to indicate its apparent secretion, and to purify native calreticulin from worm extracts by affinity chromatography. This development will allow the functional tests described above to be repeated for native calreticulin, to ascertain its role in the host–parasite relationship.
Transforming growth factor‐β suppresses interferon‐γ‐induced toxoplasmastatic activity in murine macrophages by inhibition of tumour necrosis factor‐α production
Authors: Langermans J.A.M. , Nibbering P.H. , Van Vuren‐Van Der Hulst M.E.B. , Van Furth R. 
Published: March 2003

Activation of macrophages plays an important role in the host resistance against intracellular pathogens. Various mechanisms are employed to control the activation processes and limit tissue damage by factors produced by activated macrophages. One of these mechanisms is the production of macrophage‐deactivating cytokines, such as tumour growth factor (TGF)‐β. The present study concerns the effects of TGF‐β on interferon (IFN)‐γ‐induced activation of murine macrophages with respect to induction of toxoplasmastatic activity, and production of tumour necrosis factor (TNF)‐α, prostaglandin E2 (PGE2) and reactive nitrogen intermediates (RNI). IFN‐γ activation of macrophages resulted in inhibition of T.  gondii proliferation [mean fold increase (FI) = 1·8, control mean FI = 7·0]; polymyxin B had no effect on this activation. The IFN‐γ‐induced toxoplasmastatic activity of macrophages was inhibited by TGF‐β (mean FI = 6·3), which was also found for the IFN‐γ‐induced production of TNF‐α, RNI and PGE2 by macrophages. We found that PGE2, which has macrophage deactivating properties, was not involved in the inhibition of macrophage activation by TGF‐β. The deactivating activities of TGF‐β on the IFN‐γ‐induced toxoplasmastatic activity and production of RNI are mediated by inhibition of production of TNF‐α. Addition of exogenous TNF‐α during the incubation of macrophages with IFN‐γ and TGF‐β abrogated the deactivating activity of TGF‐β. In sum, the results demonstrate that inhibition of TNF‐α production is a key factor in the TGF‐β‐induced suppression of macrophage activation with respect to toxoplasmastatic activity and RNI production.
Temporal distribution of distinct mast cell phenotypes during intestinal schistosomiasis in mice
Authors: De Jonge Frederik , Van Nassauw Luc , Van Meir Frans , Miller Hugh R. P. , Van Marck Eric , Timmermans Jean‐Pierre 
Published: March 2003

SummaryMastocytosis is a common feature of helminth infection in most host species. We examined the temporal distribution and phenotype of mast cells during intestinal schistosomiasis in mice, using antibodies directed against histamine, a general mast cell marker, against mouse mast cell protease‐1 (MMCP‐1), a mucosal mast cell (MMC) marker, and against tryptase, a predominantly connective tissue mast cell (CTMC) marker. Ileal paraffin and/or cryosections of control, 8‐ and 15‐week‐infected mice were quantitatively analysed. In the intestinal wall of non‐ and unisexual infected mice, a few dispersed mast cells were detected. In infected mice, a transient increase of mast cells in the mucosa and a gradual increase in the outer muscle layer were observed. MMCP‐1 expressing MMCs were predominantly present in the mucosa during the acute phase [8 weeks postinfection (p.i.)], while tryptase and histamine immunoreactivity demonstrated that two subsets of CTMCs were predominantly present in the outer muscle layer at 15 weeks p.i. (chronic phase). In conclusion, these results reveal that, in mice, both MMCs and CTMCs are involved in the inflammatory response during schistosomiasis. The recruitment of each mast cell population is time‐dependent and occurs at different locations. These data suggest that mastocytosis is associated with motility‐related gastrointestinal symptoms and egg excretion.
Toxocara canis antigens stimulate the production of nitric oxide and prostaglandin E2 by rat alveolar macrophages
Authors: Espinoza Elsa , Muro Antonio , Martín Manuel‐Mario Sánchez , Casanueva Patricia , Pérez‐Arellano José Luis 
Published: March 2003

SummaryThe effect of four Toxocara canis antigens on nitric oxide (NO) and prostaglandin E2 (PGE2) synthesis was studied in vitro using rat alveolar macrophages. Somatic and excretory/secretory T. canis antigens prepared from adult worms and LII larvae were incubated with rat alveolar macrophages obtained by bronchoalveolar lavage at concentrations of 0·1–50 µg/ml. Both excretory/secretory adult antigen (ESA) and somatic LII antigen (SLII) stimulate the release of nitrites by alveolar macrophages. This effect was specific (inhibited by l‐NAME and l‐canavanine) and dose‐dependent; 30 µg and 10 µg being the most effective concentrations of ESA and SLII, respectively. Western blot and reverse transcriptase‐polymerase chain reaction analyses revealed that ESA antigen stimulates the production of NO at transcriptional level. T. canis ESA also stimulated macrophages to produce PGE2 at transcriptional level. The addition of l‐canavanine decreased the release of PGE2 significantly, which suggests that NO mediates the production of this prostaglandin. These results indicate that T. canis can stimulate the release of vasodilatory mediators by macrophages of the host.
Mechanisms of apoptosis in murine fibroblasts by two intracellular protozoan parasites,Toxoplasma gondiiandNeospora caninum
Authors: Nishikawa Yoshifumi , Makala Levi , Otsuka Haruki , Mikami Takeshi , Nagasawa Hideyuki 
Published: March 2003

SummaryStudies to clarify the mechanisms of apoptosis in host cells, A31 (BALB/3T3 clone A31 fibroblasts), caused by two intracellular protozoan parasites,Toxoplasma gondiiandNeospora caninum, were carried out in anin vitrosystem. The viability ofN. caninum‐infected cells was significantly reduced following treatment with mouse interferon (IFN)‐γ. By contrast, mouse IFN‐γ treatment had no significant effect on the induction of apoptosis inT. gondii‐infected cells. Apoptosis ofN. caninum‐infected and mouse IFN‐γ‐treated cells was shown to be associated with increased DNA fragmentation, and increased caspase‐3 and ‐8 activity, and the administration of caspase‐3 and ‐8 inhibitors inhibited cell death. FasL expression was clearly induced byN. caninum‐infection and IFN‐γ treatment compared to theT. gondii‐infected cells and the uninfected control with or without IFN‐γ treatment. The reduction in host‐cell viability was prevented with the addition of antimouse FasL monoclonal antibody (mAb). Moreover, TUNEL analyses indicated that apoptosis was induced by the treatment with Fas mAb in bothT. gondiiandN. caninum‐infected cells. These results suggest that the Fas/FasL pathway may play a crucial role in the induction of apoptosis inN. caninum‐ andT. gondii‐infected cells mediated by IFN‐γ.
Diminished immunopathology in Schistosoma mansoni infection following intranasal administration of cholera toxin B‐immunodominant peptide conjugate correlates with enhanced transforming growth factor‐β production by CD4 T cells
Authors: Hernandez Hector J. , Rutitzky Laura I. , Lebens Mike , Holmgren Jan , Stadecker Miguel J. 
Published: March 2003

SummaryIn Schistosoma mansoni infection, CD4 T cells specific for parasite egg antigens mediate perioval granuloma formation in the liver and intestines. Mice of the CBA strain develop a severe form of disease and a significant proportion of their CD4 T cell response is directed against the major egg antigen Sm‐p40 and its immunodominant T cell epitope peptide 234–246. Here, we show that intranasal (i.n.) treatment of infected CBA mice with a fusion protein of the cholera toxin B subunit (CTB) with peptide 234–246 (CTB::pep) results in significant down‐modulation of hepatic granulomatous inflammation and fibrosis. Moreover, egg antigen‐stimulated dispersed hepatic granuloma cells, as well as mesenteric lymph node CD4 T cells from the CTB::pep‐treated mice, produced significantly more transforming growth factor (TGF)‐β than that produced by treated or untreated controls. The data demonstrate that i.n. administration of a single immunodominant peptide conjugated to CTB can lead to down‐regulation of the hepatic immunopathology associated with schistosomiasis, and that this down‐regulation is, at least in part, mediated by TGF‐β.
Semiochemical and physical stimuli involved in host recognition by Telenomus podisi (Hymenoptera: Scelionidae) toward Euschistus heros (Heteroptera: Pentatomidae)
Authors: Borges M. , Costa M. L. M. , Sujii E. R. , Cavalcanti M. das G. , Redígolo G. F. , Resck I. S. , Vilela E. F. 
Published: March 2003

SummaryThe egg parasitoid, Telenomus podisi, was shown to recognize its host, Euschistus heros, through both chemical and physical cues. These were determined in short‐range bioassays. The cues comprised fertile and infertile host eggs, egg extracts, crude extracts of adult males and females and successive dilutions of the synthetic racemic mixture of methyl 2,6,10‐trimethyltridecanoate, a male‐produced pheromone of E. heros.Some of the treatments used induced a selection process in T. podisi, through host recognition behaviour, indicating a consistent response of this species to E. heros. The possibility that some of these compounds could be exploited as long‐range kairomones, by T. podisi, is discussed.Using GC analysis, an unidentified compound (Rt 24.8 min), possibly from the egg adhesive material, was detected from E. heros egg extracts. Its retention time compared to the methyl 2,6,10‐trimethyltridecanoate showed a lower volatility, suggesting that the egg adhesive may act as a short‐range kairomone.Physical cues appeared to be an important component in the host selection process by T. podisi. The parasitoid discriminated infertile eggs which are differently shaped and smaller than fertile eggs.
Effects of dietary precursors to biogenic amines on the behavioural response from groups of caged worker honey bees (Apis mellifera) to the alarm pheromone component isopentyl acetate
Authors: Harris Jeffrey W. , Woodring Joseph 
Published: March 2003

SummaryThe sound or ‘buzzing response’ from groups of fifteen worker honey bees, Apis mellifera L., to the presentation of isopentyl acetate, an alarm pheromone component, was recorded through a microphone connected via a digital–analogue converter into a computer. The effects of ingested biogenic amine precursors 5‐hydroxytryptophan, L‐DOPA and tryptophan were tested on three variables measurable from the sound traces: onset of the buzzing response after presentation of the pheromone stimulus, the duration of the buzzing event, and the maximal sound frequency produced during the buzzing event. Bees fed high doses of 5‐hydroxytrytophan were found to react significantly more slowly and with a significantly lower maximum frequency than bees that were only fed sucrose controls. Bees fed DOPA were no different from controls for any of the variables measured, and bees fed tryptophan were so hyperactive that reliable responses to the presentation of alarm pheromone could not be made. Finally, the brains of worker bees fed these different precursors were examined for content of various neurochemicals. Bees fed 5‐hydroxytryptophan were found to have dose‐dependent elevations of both 5‐hydroxytryptophan and serotonin within their brains. Bees fed tryptophan were found to have dose‐dependent elevations of tryptophan and kynurenine in the brain but no change in brain serotonin. Bees fed DOPA had dose‐dependent increases in DOPA and dopamine levels within their brains. These results suggest that the hyperactive condition results from kynurenine metabolism, and the reduced response to alarm pheromone is related to serotonin metabolism.
Factors affecting behavioural responses to visual stimuli in the tomato fruit fly, Neoceratitis cyanescens
Authors: Brevault T. , Quilici S. 
Published: March 2003

AbstractResponses of Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae) females to visual stimuli were studied in a laboratory flight chamber. A bright orange sphere was used to investigate the effects of age, mating status and time of day on their responses. In no‐choice assays, four parameters were considered: mean time before leaving the release vial, percentage of flies that visited the sphere, mean number of flights and mean time before landing on the sphere. Naive mated females first became strongly responsive to the orange sphere 6 days post‐adult emergence (> 40%). The percentage of females that visited the sphere increased significantly with egg load. There were no significant differences in behavioural responses between virgin and mated mature females. In a choice situation between a yellow and an orange sphere, starved females displayed a greater propensity than well‐fed females to land on the yellow sphere. Mature females were more responsive to the orange sphere when tested in the afternoon than earlier in the day. In a no‐choice situation, females visited the yellow sphere as often as the orange sphere. However, the mean delay before landing was significantly greater for the yellow sphere. The results emphasize the importance of physiological condition on responses of N. cyanescens females to host‐simulating visual stimuli.
Expression of a costly, plastic secondary sexual trait is correlated with age and condition in a damselfly with two male morphs
Authors: Hooper Rowan E. , Tsubaki Yoshitaka , Siva‐Jothy Michael T. 
Published: March 2003

AbstractMales of the damselfly Mnais costalis Selys (Odonata: Calopterygidae) are morphologically and behaviourally polymorphic, typically existing as clear‐winged non‐territorial ‘sneaks’ and orange‐winged territorial ‘fighters’. The amount of orange pigment in the wing, as measured with a chromameter, varied between individuals, and decreased as the reproductive season progressed. Young individuals maintained in the laboratory on high or low nutrient diets differed in the amount of pigment that developed in the wing. Males in the high nutrient group developed darker wings faster than those in the low nutrient group. Young adults of both sexes and morphs were fed 14C‐radiolabelled tryptophan or tyrosine (precursors of the pigments ommochrome and melanin, respectively). Ommochrome was restricted to the pseudopterostigma of the males of both morphs and was not present in females. The presence of tyrosine in the wing cells of orange males, but not of clear males, indicated that the orange pigment is at least partly constituted from melanin. These data show that at least some pigment levels must be maintained continuously in the wings of orange males, and that maintenance is costly as it is compromised at low nutrient levels.
The biosynthesis of Juvenile Hormone, its degradation and titres in females of the true armyworm: a comparison of migratory and non‐migratory populations
Authors: McNeil Jeremy N. , Miller David , Laforge MarlÈne , Cusson Michel 
Published: March 2003

SummaryIn a previous study [McNeil et al. (1996)
Archives of Insect Biochemistry and Physiology, 32, 575–584], patterns of sexual maturation and Juvenile Hormone (JH) biosynthesis were compared in virgin females from migratory (North American) and non‐migratory (Azorean) populations of the true armyworm moth, Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae). Sexual maturation occurred at a significantly earlier age after emergence in the non‐migrant population, and the rates of biosynthesis of JH in vitro suggested that lower titres of JH may be required to initiate the onset of calling behaviour (pheromone emission) and ovarian development in Azorean females. To examine the physiological differences in the reproductive biology of migratory and non‐migratory populations in greater detail, the haemolymph titres of JH and JH esterase activity were compared in virgin females as a function of age. In addition, the effects of mating on JH biosynthesis in vitro, JH titres, JH esterase activity and egg production were measured in the two populations. As expected, JH titres rose more rapidly after emergence in Azorean females than in their North American counterparts but, contrary to our prediction, the maximum levels were also higher in the non‐migrant population. Activity of JH esterase was much higher in Azorean females on the day of emergence. However, by the second day both populations had similar activity levels (about 17 nmol JH/min/ml) and exhibited a similar age‐related decline in subsequent days.Mating did not affect the rate of JH biosynthesis in vitro but resulted in a significant increase in the titres of JH in the haemolymph of both populations. The maximum titre (a five‐fold increase) occurred within 24 h of mating in Azorean females. In North American individuals the increase was greater (seven‐fold) but did not occur until 48 h after mating. No difference in the activity of JH esterase was observed between mated and virgin North American females. By contrast, while there was an age‐related decline in the activity of JH esterase in mated Azorean females, as seen in both North American groups, activity levels in virgin females remained constant with age. In all females, mating resulted in a significant increase in egg production within 24 h.The Azores is a volcanic archipelago, so these non‐migratory populations were probably founded by immigrants originating from migratory continental populations. It is clear from our results that the change from a life history that includes migration to a non‐migratory one involved more than just a temporal shift in the timing of the production of JH. Furthermore, the interpopulation differences in titres of JH and mating‐induced changes reported here cannot be fully explained by the observed differences in the patterns of activity of JH esterase and JH biosynthesis in vitro.
Diapausing pupae of the flesh fly Sarcophaga crassipalpis (Diptera: Sarcophagidae) are more resistant to inoculative freezing than non‐diapausing pupae
Authors: Kelty Jonathan D. , Jr Richard E. Lee 
Published: March 2003

SummaryThe resistance of diapausing (overwintering) and non‐diapausing (summer) Sarcophaga crassipalpis (Diptera: Sarcophagidae) pupae to inoculative freezing was examined. Although both types of pupae resisted inoculative freezing after 24‐h submergence in water, diapausing pupae were overall significantly more resistant than non‐diapausing pupae. Exposing the thin pupal cuticle by removing the ends of the puparial case eliminated the capacity of both pupal types to resist inoculative freezing, indicating that resistance to inoculative freezing resides with the puparium. Pupae submerged in surfactant solution were significantly less resistant to inoculative freezing than those submerged in water. Furthermore, the puparial water content of pupae submerged in surfactant solution was significantly greater than that of puparia from pupae submerged in water. Surfactant may have promoted inoculative freezing by facilitating the spread of water over the surface of and into the puparium, thereby creating bridges between external ice and pupal body fluids. Extracting puparial surface lipids with chloroform/methanol (2 : 1, v:v) decreased the resistance of non‐diapausing pupae to inoculative freezing but did not significantly affect that of diapausing pupae. This finding indicates that the puparium of diapausing pupae contains protection against inoculative freezing separate from its surface lipids. This barrier may be important in protecting the freezing‐intolerant overwintering pupae against inoculative freezing within their soil hibernaculum.
Habituation of sexual response in male Heliothis moths
Authors: Daly Kevin C. , FigUeredo Aurelio JosÉ 
Published: March 2003

SummaryIt has been generally hypothesized that habituation mediates the effects of pheromone‐based disruption strategies used in the management of moth pests. The current study demonstrates that pheromone‐mediated sexual response in the tobacco budworm moth, Heliothis virescens (F.) (Lepidoptera: Noctuidae), can in fact be modulated by conditions consistent with the production of habituation. An ethogram was used to measure response strength in a wind tunnel experiment where male moths were allowed to respond freely to one of two different blends of female pheromone in 16 trials over 4 days. Post‐test measures were collected to investigate stimulus specificity and long‐term effects. In conditions appropriate to the formation of habituation, habituation will develop and disrupt male sexual response to female sex pheromone. Males repeatedly exposed to plumes of synthetic pheromone blends display a habituated response lasting up to 96 h. Habituation rate and spontaneous recovery of response strength are greater with less intense stimuli. Additionally, males habituated to one blend express no habituation of sexual response when exposed to a different blend. This indicates a high degree of stimulus specificity, which could facilitate outbreeding, and that moths attend to the configuration of the pheromone blend, not simply to its elements.
A taste receptor neurone dedicated to the perception of pyrrolizidine alkaloids in the medial galeal sensillum of two polyphagous arctiid caterpillars
Authors: Bernays E. A. , Chapman R. F. , Hartmann T. 
Published: March 2003

Abstract.It is shown that pyrrolizidine alkaloids are phagostimulants for the caterpillars of two polyphagous arctiid caterpillars, Estigmene acrea and Grammia geneura. The caterpillars will also eat dry glass‐fibre discs containing only pyrrolizidine alkaloid − an example of pharmacophagy. The tip‐recording technique is used to demonstrate that each species has a neurone in the medial galeal styloconic taste sensillum responding to pyrrolizidine alkaloids, although the species differ in their sensitivities. This neurone responds to at least four different pyrrolizidine alkaloids and their N‐oxides, and experiments indicate that it is dedicated to perception of these compounds. The sensory response is phasic–tonic and during the tonic phase remains unchanged for at least 500 ms, resembling the type of response often seen in neurones that are sensitive to plant secondary compounds producing deterrent effects.