bluuebunny/crossref_metadata_2025 huggingface dataset:
Mucosal mast cell responses and release of mast cell protease‐I in infections of mice with Hymenolepis diminuta and H. microstoma: modulation by cyclosporin A
Authors: McLAUCHLAN  , ROBERTS  , LOXTON  , WASTLING  , NEWLANDS  , CHAPPELL
Published: March 2003

The dynamics of intestinal mucosal mast cells and the major mucosal mast cell protease were followed during the course of laboratory infections of mice with Hymenolepis diminuta and H. microstoma. The effects of the drug cyclosporin A (CsA), which is both immunosuppressive and selectively anthelmintic depending upon dose regime, were determined. In H. diminuta infections worm expulsion occurred around day 9 and coincided with peak mastocytosis and peak mMCP‐I concentrations in tissues and serum. Immunosuppressive treatment with CsA prevented worm expulsion, permitting some individuals to reach maturity, and abrogated mast cell proliferation and mMCP‐I production and release. By contrast, H. microstoma infections persisted for 64 days in spite of a considerable mastocyosis in both intestine and bile duct tissues accompanied by a high level of mMCP‐I in tissues and serum. A subimmunosuppressive regime of CsA had only limited effects on worms and mast cell numbers and activity. Together these data shed light on the variable mast cell response to gastrointestinal infections and on the potential significance of parasite location in evasion of mast cell action. Use of CsA reveals the contributions of both T cell‐dependent mechanisms, including mast cell proliferation and activation, and T cell‐independent events in regulating intestinal helminth infections.
Susceptibility to Trypanosoma cruzi is modified by a previous non‐related infection
Authors: RODRÍGUEZ MIRIAM , TERRAZAS LUIS I. , MÁRQUEZ RICARDO , BOJALIL RAFAEL
Published: March 2003

Helminth infections are frequently massive, chronic and strong inductors of Th2‐type cytokines. This implies that infection by such parasites could alter the susceptibility to subsequent infections by other pathogens, particularly intracellular parasites. We therefore explored whether a persistent infection, caused by Taenia crassiceps cysticerci, in BALB/c mice could affect susceptibility to a later infection by Trypanosoma cruzi. We found that the presence of the cysticerci indeed modified the immune response and the susceptibility to T. cruzi, and that these modifications depended on the time‐course evolution of the initial infection. Coinfection with the protozoan in the early stages of the helminth infection, induced a delay on the onset of parasitaemia, early specific production of IFN‐γ and high specific production of IL‐4. A significant increase in susceptibility to T. cruzi was observed only when mice were coinfected in late stages when the helminth load is greater and a Th2 type response against it is predominant. The in vitro specific response to T. cruzi antigens was then characterized by low levels of both IFN‐γ and IL‐4. These findings suggest that chronic helminth infections could potentially have a significant influence over the immune response and hence susceptibility to other pathogens.
Susceptibility of B‐cell deficient C57BL/6 (μMT) mice to Neospora caninum infection
Authors: EPERON  , BRÖNNIMANN  , HEMPHILL  , GOTTSTEIN
Published: March 2003

Neospora caninum is a coccidian parasite of veterinary importance by causing abortion or stillbirth in cattle among other problems in diverse animal species. We assessed an experimental murine model for its suitability to study the immune response to N. caninum infection. Thus, wild‐type (wt) C57BL/6 mice and B‐cell (and consequently antibody)‐deficient μMT mice were infected with N. caninum tachyzoites and sacrificed at days 10, 24 and 29–44 post infection (dpi). Various organs were collected for parasitological and pathological analysis, spleen and serum for immunological investigations. Splenocytes were in vitro‐stimulated with N. caninum (NC)‐ and T. gondii‐antigens for assessing T cell proliferation and cytokine production. While wt mice were resistant to disease, μMT mice died starting from 29 dpi onwards. Histological examination of brain tissue from μMT mice exhibited a high infection intensity with multifocal necrotic cerebral lesions, which were absent in the brains of wt mice. NC antigen‐stimulated spleen cells of both wt and μMT mice infected with N. caninum showed a marked proliferative depression at 10 dpi. At 24 dpi, this immunosuppression was still maintained in μMT mice whereas it was restored in wt mice. Stimulated splenocytes of infected μMT mice secreted significantly less IFN‐γ and less IL‐10 than corresponding wt splenocytes. For IL‐10, this difference increased with time. The susceptibility of μMT mice appeared associated to B‐cell deficiency, allowing the persistant spread of the parasite causing immunosuppression and finally resulting in a lethal outcome of infection.
Local and systemic cytokine expression during experimental chronic Trypanosoma cruzi infection in a Cebus monkey model
Authors: Samudio Margarita , Montenegro‐James Sonia , Kasamatsu Elena , Cabral Margarita , Schinini Alicia , Rojas De Arias Antonieta , James Mark A.
Published: March 2003

Cebus apella is an acceptable model for chronic chagasic cardiomyopathy (CCC), since it is possible to experimentally induce cardiac lesions after 1 year of Trypanosoma cruzi infection. The T. cruzi Y strain, shown previously to produce CCC in C. apella monkeys, was used to experimentally infect 10 monkeys. Parasitological, serological and clinical parameters were monitored during a 19‐month follow‐up, and systemic cytokine responses were assessed sequentially in five monkeys selected according to the differential parasitemia pattern exhibited. Ten additional monkeys, infected with the same strain for 5, 10 and 12 years, were analysed cross‐sectionally. Three monkeys/time point and one uninfected control animal were sacrificed for gross pathology, histology, presence of parasites, and local cytokine gene expression. Elevated expression of interleukin (IL)‐4 was observed throughout the study in monkeys that had persistent, high parasitemias, whereas a high level of interferon (IFN)‐γ was seen in monkeys that controlled parasitemias soon after infection. Chronically infected monkeys expressed a nonpolarized, Th0‐type response. Cardiac tissue collected from a monkey that succumbed to acute infection had elevated levels of proinflammatory cytokine [IL‐1β, IL‐6, tumour necrosis factor‐α] and interstitial cell adhesion molecule (ICAM)‐1, platelet‐derived growth factor (PDGF)‐α, transforming growth factor (TGF)‐β and IL‐10 transcripts. Cytokine production in cardiac tissue of chronically infected monkeys was also characterized by elevated expression of ICAM‐1, PDGF‐α and TGF‐β, which correlated with the detection of T. cruzi DNA by polymerase chain reaction.
The immunomodulatory factors of bloodfeeding arthropod saliva
Authors: Gillespie  , Mbow  , Titus Richard G.
Published: March 2003

There are potent immunomodulators in saliva of the bloodfeeding arthropods which transmit many of the world's most serious diseases that may benefit the arthropod by preventing the vertebrate host from becoming sensitized to the saliva. In addition, saliva can enhance transmission of parasites/pathogens by arthropods. As a result, vaccines that target the arthropod (e.g. salivary immunomodulators) should be considered as one component of multisubunit vaccines against arthropod‐borne parasites/pathogens. Indeed, since vaccines against the pathogens themselves are often not fully protective, vaccines that target several facets of the life cycle of the pathogen may be the most effective at controlling disease transmission. This review covers known immunomodulatory factors in arthropod vector saliva, focusing mainly on sandflies and ixodid ticks.
Native and recombinant antigens in the immunodiagnosis of human cystic echinococcosis
Authors: Ortona Elena , Riganò Rachele , Margutti Paola , Notargiacomo Sergio , Ioppolo Salvatore , Vaccari Sergio , Barca Stefano , Buttari Brigitta , Profumo Elisabetta , Teggi Antonella , Siracusano Alessandra
Published: March 2003

To evaluate the diagnostic sensitivity and specificity of immunoelectrophoresis (IEP), indirect haemagglutination (IHA), enzyme‐linked immunosorbent assay (ELISA) and immunoblotting (IB), we compared their ability in detecting IgG antibodies to a hydatid fluid fraction (HFF) and to native and recombinant antigen B of Echinococcus granulosus. We tested sera from patients who had cystic echinococcosis (CE) grouped according to their type of cysts (n = 204), from patients with other parasitic diseases (n = 21), lung or liver carcinomas (n = 6) or serous cysts (n = 26) and from healthy controls (n = 90). HFF‐IB gave the highest sensitivity (80%) followed by ELISA (72%), IHA (54%) and IEP (31%), respectively. The diagnostic sensitivity significantly (P < 0.01) decreased as cysts matured from type I‐II to type VII. Recombinant and native antigen B‐IB yielded similar sensitivity (74%). A large number of clinically or surgically confirmed CE patients (20%) resulted negative. In these patients' sera, IB to assess the usefulness of the recombinant E. granulosus elongation factor‐1β/δ in detecting IgE antibodies yielded 33% of positivity. Our findings underline the need to standardize techniques and antigenic preparations and to improve the performance of immunodiagnosis by characterizing new antigens and detecting distinct immunoglobulin classes.
Antibodies raised against the flagellar pocket fraction of Trypanosoma brucei preferentially recognize HSP60 in cDNA expression library
Authors: Radwanska Magdalena , Magez Stefan , Dumont Nathalie , Pays Annette , Nolan Derek , Pays Etienne
Published: March 2003

A purified flagellar pocket fraction of the Trypanosoma brucei AnTat 1.1E clone was used for the generation of polyclonal antiserum in rats. Anti‐flagellar pocket antibodies present in this serum recognized several proteins distinct from the major variant surface glycoprotein (VSG). In Balb/c mice, flagellar pocket immunization resulted in partial resistance towards the challenge with a low dose of parasites. This was accompanied by the induction of specific IgG2a antibodies. In an attempt to discover protective parasite antigens, antiflagellar pocket serum was used for the screening of a T. brucei bloodstream form cDNA library constructed in the λgt11 bacteriophage expression system. Through antibody panning and VSG elimination, 15 specific cDNA inserts were selected. Most intriguing was the observation that in addition to two clones encoding the invariant surface glycoprotein 75 (ISG75), 10 out of 15 independently selected cDNA inserts encoded the trypanosome heat shock protein 60 (tHSP60).
Growth kinetics of leukocyte cell lines cultured with hydatid fluid of Echinococcus granulosus equinus
Authors: Macintyre A.R. , Dixon J.B. , Green J.R.
Published: March 2003

Oxidation of 3,(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) and tritiated thymidine uptake were used to measure, respectively, the viable cell count and the S‐phase activity of D10, B9, A20 and p388d leukocytic cell lines cultured in the presence of varying concentrations of fluid from fertile and infertile hydatid cysts of Echinococcus granulosus equinus. Exposure to hydatid fluid raised or lowered the entry of D10 cells into S‐phase depending on the concentration of the fluid and of the supporting cytokines. Enlargement of the S‐phase population was unaccompanied by increase in viable count indicating that the mitotic cycles induced by hydatid products were not completed. A similar conclusion was reached in respect of the p388d monocytic line, and both changes appear consistent with those occurring in histopathology in vivo. By contrast, the main effect on B9 and A20 B cells was inhibition of entry into S‐phase.
Do maternally acquired antibodies protect infants from malaria infection?
Authors: Riley E.M. , Wagner G.E. , Akanmori B.D. , Koram K.A.
Published: March 2003

Neonates and infants are relatively protected from clinical malaria, but the mechanism of this protection is not well understood. Maternally derived antibodies are commonly believed to provide protection against many infectious diseases, including malaria, for periods of up to 6–9 months but several recent epidemiological studies have produced conflicting results regarding a protective role of passively acquired antimalarial antibodies. In this article, we review the epidemiological evidence for resistance of young infants to malaria, summarize the data on antimalarial antibody levels and specificity and their association with protection from malaria infection or clinical disease, and explore alternative explanations for resistance to malaria in infants.
Vaccine efficacy of recombinant cathepsin D aspartic protease from Schistosoma japonicum
Authors: Verity Christiana K. , McManus Donald P. , Brindley Paul J.
Published: March 2003

Mice were vaccinated with recombinant Schistosoma japonicum cathepsin D aspartic protease, expressed in both insect cells and bacteria, in order to evaluate the vaccine efficacy of the schistosome protease. Mean total worm burdens were significantly reduced in vaccinated mice by 21–38%, and significant reductions in female worm burdens were also recorded (22–40%). Vaccination did not reduce fecundity; rather, we recorded increased egg output per female worm in vaccinated animals, suggesting a crowding effect. Vaccinated mice developed high levels of antibodies (predominantly IgG1, IgG2a and IgG2b isotypes), but there was no correlation between antibody levels and protective efficacy. Immune sera from vaccinated mice did not inhibit the   degradation of human haemoglobin by the recombinant protease, and passive transfer of serum or antibodies from vaccinated animals, before and after parasite challenge, did not significantly reduce worm or egg burdens in recipient animals. These results suggest that antibodies may not play a key role in the protective effect elicited, and that protection may be due to a combination of humoral and cell‐mediated responses
The 14‐3‐3 protein as a vaccine candidate against schistosomiasis
Authors: Schechtman Deborah , Tarrab‐Hazdai Rebecca , Arnon Ruth
Published: March 2003

We have previously reported on the cloning of the 14‐3‐3 protein of Schistosoma mansoni. Here, we evaluate the potential use of this protein as a vaccine candidate against infection by S. mansoni. Sm14‐3‐3 was expressed and purified either as a free protein or as a fusion protein to SjGST or MBP. Sera from mice infected with S. mansoni recognized both SjGST and 14‐3‐3, indicating that antibodies against these two proteins are induced in the course of the natural infection. Furthermore, mice immunized with either 14‐3‐3, GST or 14‐3‐3‐GST, reacted with cercaria lysate. A cellular immune response was also detected, particularly in mice immunized with 14‐3‐3‐GST. With respect to the effect on biological functions, antibodies to 14‐3‐3 and 14‐3‐3‐GST caused 23–32% complement‐mediated cytotoxcity of S. mansoni schistosomula compared to only 10–11% induced by either normal mouse serum, or GST alone. In challenge infection with S. mansoni, immunization with 14‐3‐3, either as a fusion protein or as a free protein, led to protection ranging from 25–46%, as determined by reduction of adult worm burden, while SjGST alone elicited only 0–8% protection and MBP alone did not elicit any protection.
Divergent roles for macrophages in lymphatic filariasis
Authors: Allen Judith E. , Loke P'Ng
Published: March 2003

Macrophages have long been recognized as important cells associated with filarial infection but their function as effectors and/or suppressors has not been elucidated. Recent advances in our understanding of the role that macrophages may play in lymphatic filariasis have come from in vitro studies and mouse models of filarial infection. Based on these new findings, we hypothesize that while dead or dying worms induce the ‘classical’ activation of macrophages and a subsequent pro‐inflammatory response, live and healthy worms secrete products that induce type 2 cytokines and the differentiation of ‘alternatively’ activated macrophages that downregulate an inflammatory response. Thus, the balance between the ‘classical’ and ‘alternative’ activation pathways of macrophages could be an important factor in inflammatory pathology associated with filariasis.
Arginase I induction in macrophages, triggered by Th2‐type cytokines, supports the growth of intracellular Leishmania parasites
Authors: Iniesta Virginia , Carlos Gómez‐Nieto L. , Molano Isabel , Mohedano Alicia , Carcelén Jesualdo , Mirón Cristina , Alonso Carlos , Corraliza Inés
Published: March 2003

Leishmania spp. are intracellular protozoan parasites that invade and replicate within macrophages. In a previous report, we have demonstrated that the growth of intracellular amastigotes could be controlled by inhibition of arginase. This enzyme, induced in host cells by Th2 cytokines, synthesizes L‐ornithine which can be used by parasites to generate polyamines and proliferate. In this study, we have designed experiments to better analyse the dependence of parasite proliferation on arginase induction in infected macrophages. Treatment of Leishmania major‐infected BALB/c macrophages with interleukin (IL)‐4, IL‐10 or transforming growth factor‐β, which are all inducers of arginase I in murine macrophages, led to a proportional increase in the number of intracellular amastigotes. Moreover, parasite proliferation and arginase activity levels in macrophages from the susceptible BALB/c mice were significantly higher than those from infected C57BL/6 cells when treated with identical doses of these cytokines, indicating that a strong correlation exist between the permissibility of host cells to L. major infection and the induction of arginase I in macrophages. Specific inhibition of arginase by Nω‐hydroxy‐nor‐L‐arginine (nor‐LOHA) reverted growth, while L‐ornithine and putrescine promoted parasite proliferation, indicating that the parasite cell division depends critically on the level of L‐ornithine available in the host. Therefore, arginase induction in the context of a Th2 predominant response might be a contributor to susceptibility in leishmaniasis.
Serotonin modulates a photic response in circadian locomotor rhythmicity of adults of the blow fly, Calliphora vicina
Authors: CYMBOROWSKI BRONISŁAW
Published: March 2003

Abstract. The present experiments were undertaken to explore a role for serotonin (5‐hydroxytryptamine, 5‐HT) in modulating photic signal transduction in photoreceptors of the blow fly, Calliphora vicina. Injection of p‐chlorophenylalanine (pCPA) into the haemolymph appeared to reduce sensitivity to the photic effects of constant ‘bright’ light (LL hyperactivity and circadian arrhythmicity). After drug injection in bright LL, flies continued with a free‐running rhythm as in constant darkness (DD) or with a lengthened period τ as in ‘dim’ LL. When 5‐HT was injected into flies kept in dim LL, they became hyperactive and arrhythmic as in bright LL. This finding suggests a potential role for serotonin as mediator of circadian changes in the insect visual system including extraretinal photoreceptors.
Feeding behaviour, digestive physiology and lipid content in macropterous females of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)
Authors: SOCHA R. , ŠULA J. , ZEMEK R.
Published: March 2003

Abstract. Macropterous females of Pyrrhocoris apterus (L.) reared under short‐day conditions (LD 12:12 h) were analysed for temporal patterns of feeding and drinking behaviour, activities of digestive enzymes in the gut, and lipid and glycogen content in the haemolymph and fat body. Peaks of drinking activity were recorded at days 3, 7 and 10 during the first 14 days after imaginal ecdysis. Feeding activity peaked on the third day, ceasing completely after the fourth day of adult life. Esterase, protease, amylase and aminopeptidase activities exhibited the highest overall activity in the first days after imaginal emergence; then enzyme activities decreased. In the fat body, the content of lipids was highest on day 5, then a decrease of about 40% was observed at day 14; the amount of glycogen was highest on day 1 at 11 μg of glucose equivalents/mg of fat body, then decreased to 2 μg at day 14 after the imaginal moult. In the haemolymph, the lipid content rose until day 8 when it reached almost 0.3 μmol/μl; at day 14 the value was slightly lower. The association of fasting with reproductive arrest in macropterous females of P. apterus, accompanied by a decrease in digestive enzyme activities and a mobilization of lipid reserves from the fat body, was demonstrated.
GABA and picrotoxin alter expression of a maternal effect that influences pupal diapause in the flesh fly, Sarcophaga bullata
Authors: WEBB MEI‐LING , DENLINGER DAVID
Published: March 2003

A maternal effect that operates in the flesh fly, Sarcophaga bullata Parker (Diptera: Sarcophogidae), prevents the expression of pupal diapause in the progeny of females that have been reared under short day conditions. This set of experiments tests the possibility that the maternal effect can be prevented by the use of various environmental stresses or chemical treatments administered to the mother. High and low temperature shocks, food deprivation and reducing the size of the mother were all ineffective in altering transmission of the diapause‐suppressing maternal effect. Several chemical agents, however, were effective. Gamma‐aminobutyric acid (GABA) and one of its antagonists, picrotoxin, elicited opposite responses when injected into female flies. Whereas GABA suppressed the incidence of diapause in the female’s progeny, picrotoxin increased the diapause incidence, thus suggesting the possibility of a central role for GABA in regulation of the maternal effect. Octopamine and pilocarpine injected into females also were effective in countering the maternal effect and thus permitting expression of diapause in the female’s progeny.
Field responses of stink bugs to the natural and synthetic pheromone of the Neotropical brown stink bug, Euschistus heros (Heteroptera: Pentatomidae)
Authors: BORGES M. , SCHMIDT F. G. V. , SUJII E. R. , MEDEIROS M. A. , MORI K. , ZARBIN P. H. G. , FERREIRA J. T. B.
Published: March 2003

Abstract.The synthetic racemic mixture of methyl 2,6,10‐trimethyltridecanoate, a component of the male produced pheromone of Euschistus heros (F.) (Heteroptera, Pentatomidae), was attractive to pentatomid species in a field test, using homemade pheromone trap designs. The pentatomid Piezodorus guildinii was caught in high numbers in field traps, during two field experiments, indicating a consistent response of this species to the E. heros pheromone. A correlation was found between the range of insects caught in the pheromone‐baited traps and a random sampling method. The synthetic stereoisomeric mixture of methyl 2,6,10‐trimethyldodecanoate, a minor component of E. heros pheromone, was also field tested and caught no pentatomids. Egg parasitoids were caught in traps baited with E. heros pheromone, indicating that this pheromone can be exploited as a kairomone. A synchrony in the periodicity of trap catch, between the egg parasitoids and their host, was also recorded.
Determination of allatostatin levels in relation to the gonadotropic cycle in the female of Blattella germanica (L.) (Dictyoptera, Blattellidae)
Authors: Vilaplana Lluïsa , Maestro José. L. , Piulachs Maria‐Dolors , Bellés Xavier
Published: March 2003

A polyclonal antibody against the allatostatin BLAST‐3 (AGSDGRLYSFGL‐NH2) of the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae) has been raised and characterized, and an ELISA (enzyme‐linked immunosorbent assay) for allatostatin quantification has been developed. Allatostatin contents in brain, midgut and haemolymph have been measured in females of B. germanica during the first gonadotropic cycle. Brain allatostatin content increases steadily from adult emergence to the formation of the first ootheca. The values range from 2 ng/brain on the day of adult emergence to 25 ng/brain when the insect forms the ootheca 8 days later. In the midgut, the pattern is similar but the values are about half those of the brain. Allatostatin concentrations in the haemolymph after HPLC separation are in the nanomolar range. The occurrence of allatostatins in the haemolymph suggests that these peptides can act through a humoral pathway, as well as via nerves. The allatostatin content of both brain and midgut are high while the female is transporting the ootheca, which suggests that these peptides could be related to the low metabolic status characterising the period of oothecal transport.
Nutritional requirements for web synthesis in the tetragnathid spider Nephila clavipes
Authors: Higgins Linden , Rankin MarY. AnN.
Published: March 2003

Trap‐constructing organisms provide a unique opportunity for the study of resource allocation, because an observer can unambiguously determine the allocation to foraging. In species that synthesize a trap from physiologically important compounds, there is the further advantage that there may be direct trade‐offs between allocation of resources to foraging and physiological functions. We examined the ability of the spider Nephila clavipes (L.; Araneae: Tetragnathidae) to synthesize resources that are known to be used for both web synthesis and non‐foraging physiological functions. We found that choline, required for both web function and physiological function, is an essential nutrient: it is not synthesized by this spider. Under laboratory conditions with a diet of fruit flies, choline is limiting, and the spiders make allocation trade‐offs between investing choline in foraging (the web) or in their body.
Behavioural and physiological responses to conflicting oviposition stimuli in a synovigenic parasitoid
Authors: Gauthier N. , Monge J. P.
Published: March 2003

The behavioural and physiological responses of the synovigenic parasitoid, Dinarmus basalis (Rond.) (Hymenoptera: Pteromalidae), were investigated whilst the wasps were submitted to conflicting oviposition stimuli: an environment which induced them to restrict egg‐laying and a physiological factor, egg‐load pressure, which induced them to lay eggs. When individual females depleted patches containing hosts parasitized 24 h or 72 h beforehand, they laid preferentially on unparasitized hosts and the number of eggs laid decreased significantly. Although they remained for several days in such patches, egg‐load pressure did not lead them to modify their strategy (i.e. to accept all the available hosts including the already parasitized ones). In this synovigenic species, the oviposition constraint resulted in the retention of oocytes. Dissection and histological observation showed that the unlaid eggs are resorbed, a reproductive regulatory process which has seldom previously been reported in the presence of unparasitized hosts. This physiological response was induced by the mere presence of the parasitized hosts rather than their density. The females’ response was also influenced by the presence of conspecifics. They still avoided laying on parasitized hosts but the number of eggs laid daily became comparable to that observed in patches containing only unparasitized hosts. Thus, D. basalis females adapted their strategy in response to their environment, in which the most significant factor seemed to be the quality of the hosts provided, and their physiology. The originality and the importance of these results are discussed.
Stage‐specific effects of temperature and dietary protein on growth and survival of Manduca sexta caterpillars
Authors: Petersen C.H.ristine , Woods H. Arthur , Kingsolver J.O.E.L. G.
Published: March 2003

The effects of temperature and dietary protein concentration on growth and survival of Manduca sexta L. (Lepidoptera: Sphingidae) caterpillars during different larval stages were examined. Sets of caterpillars were raised from hatching at one of five constant temperatures (18, 22, 26, 30 or 34°C) and on one of two artificial diets (low or high protein concentration). Mass gain, duration (development time) and mean growth rate were measured for each caterpillar for the 1st to 3rd stadia, the 4th stadium, and the 5th stadium. Temperature significantly affected mass gain during each larval stage, resulting in smaller mass gains at higher temperatures at each stage. This effect was strongest at high temperatures during the 5th stadium. Temperature significantly affected durations of each larval stage, but the effect varied among stages: for example, the duration of stadia 1–3 decreased continuously with increasing temperature, whereas the duration of the 5th stadium was shortest at 26–30°C and increased at lower and higher temperatures. The effect of temperature on mean growth rate changed dramatically across larval stages: maximal growth rate occurred at 34°C during the 1st to 3rd stadia, at 30°C during the 4th stadium and at 26°C during the 5th stadium. Higher dietary protein concentration significantly decreased the duration of stadia 1–3 and of the 4th stadium, but had no significant effect on the duration of the 5th stadium. Temperature and dietary protein had little effect on mortality rates during any larval stadium, with one exception: mortality during the 5th stadium increased dramatically at temperatures of 30 and 34°C. These results demonstrate that the effects of temperature and dietary protein concentration on growth, development and survival in M. sexta vary markedly in different larval stadia during development; 5th instar caterpillars are particularly sensitive to higher temperatures.
Host‐selection behaviour by genetically identical aphids with different plant preferences
Authors: Powell G.L.E.N. , Hardie J.I.M.
Published: March 2003

The behaviour of summer and autumn winged forms of the black bean aphid, Aphis fabae Scopoli (Homoptera: Aphididae), was compared on two plants utilized at different stages of the insect’s life cycle. Adult autumn migrants (gynoparae) are monophagous, colonizing spindle (Euonymus europaeus), whereas polyphagous summer winged aphids (alate virginoparae) are associated with a variety of herbaceous plants, including broad bean (Vicia faba). When aphids from a single clone were given access to a spindle leaf and a bean seedling in choice tests, many virginoparae settled and larviposited on both plant species over 24 h. By contrast, gynoparae showed a clear preference for spindle, with 93.5% of settled adults and 98.3% of larvae on this plant species. Close‐up video monitoring showed that gynoparae discriminated beans from spindle within a 5‐min period, whereas virginoparae behaved similarly on both plant species. For gynoparae, the major behavioural difference on the two plants appeared after a brief (epidermal) stylet penetration, with many insects taking flight within a few seconds of stylet withdrawal from bean. Factors detected during stylet insertion by gynoparae must therefore inhibit take‐off on spindle. Electrical recording experiments showed that aphids often punctured a cell membrane during brief probes on both plant species, and intracellular stylet activities always included a waveform associated with ingestion. When gynoparae puncture spindle cells their behaviour is probably modified by intracellular metabolites detected via gustation of ingested epidermal cell sap. These cues may inhibit the take‐off reflex which otherwise follows probing.
Cold tolerance, overwintering and establishment potential of Thrips palmi
Authors: McDonald Jamie R. , Head Justine , Bale Jeffrey S. , Walters Keith F. A.
Published: March 2003

The cold tolerance and overwintering survival of the quarantine regulated pest and virus vector, Thrips palmi (Karny) (Thysanoptera: Thripidae), is examined and discussed in terms of its establishment potential in the U.K. Thrips palmi adults and first‐instar larvae have a wide distribution of supercooling points (SCPs) but show ‘pre‐freeze’ mortality as a result of both acute and chronic exposures to temperatures above the SCP range. Thrips palmi did not develop enhanced cold tolerance in response to cues previously shown to cold‐acclimate other thrips species. The acute cold tolerance of T. palmi is higher than that of the recently established and biologically similar species, Frankliniella occidentalis, which is thought to be capable only of very limited winter survival outdoors in the U.K. However, the more ecologically meaningful chronic assays reveal the opposite pattern. If introduced to the U.K., overwintering of T. palmi would thus be largely restricted to protected environments, as its cold tolerance is insufficient to permit outdoor survival for a complete winter. This assertion was demonstrated by caged populations that died out after as little as 25 days in outdoor winter conditions in Yorkshire, U.K. The reversal of relative tolerance of the two species when considering chronic and acute assays suggests that these forms of low temperature mortality have different physiological bases, and emphasizes the need to use both forms of assay in assessments of overwintering capacity.
Structure of host‐odour plumes influences catch of Anopheles gambiae s.s. and Aedes aegypti in a dual‐choice olfactometer
Authors: Dekker Teun , Takken Willem , Cardé Ring T.
Published: March 2003

The effects of structure, concentration and composition of host‐odour plumes on catch of female Anopheles gambiae Giles sensu stricto and Aedes aegypti (L.) (Diptera: Culicidae) were investigated in a dual‐choice olfactometer. We demonstrate that the fine‐scale structure of host‐odour plumes modulates capture of An. gambiae and Ae. aegypti. In both species homogeneous skin‐odour plumes result in trap entry, whereas homogeneous CO2 plumes reduce trap catch. Reduced trap catch also result from combining skin odour with a homogeneous CO2 plume. Trap capture rates in homogeneous CO2 plumes were concentration‐dependent and differed between the two species. Electric nets placed in front of the trap entrances intercepted mosquitoes before they could enter the traps. This showed that An. gambiae flew along CO2 plumes, but did not enter the traps. Survivorship analysis of the trap‐entry times of Ae. aegypti indicated interactions between the time until capture and treatment. The assay's duration therefore can alter the distribution in a dual‐choice olfactometer.
Aggressive behaviours of female Drosophila melanogaster are influenced by their social experience and food resources
Authors: Ueda Atsushi , Kidokoro Yoshiaki
Published: March 2003

Abstract Aggressive behaviours of female Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) were studied in the laboratory. These behaviours included ‘approach’, a seemingly intentional movement of a fly to another fly, ‘lunge’, a dash at another fly, and ‘wings erect’, a brief erection of wings toward another fly. These behaviours were influenced by social experience and food resources. First, event frequencies of aggressive behaviours were higher in flies that had been held in isolation than in those that had been held in crowded conditions. This difference was the result of the social experience of attacking flies and not that of attacked flies. Second, flies showed aggressive behaviours more frequently when they were on food containing yeast colonies than when they were on food without yeast colonies. Third, flies conditioned to a food solution containing live yeast prior to observation showed lower frequency of aggressive behaviours than flies conditioned to a boiled food solution. Development of aggressive behaviours became apparent one day after eclosion.
Potential mechanism for detection by Apis mellifera of the parasitic mite Varroa destructor inside sealed brood cells
Authors: Martin Caroline , Provost Eric , Bagnères Anne‐Geneviève , Roux Maurice , Clément Jean‐Luc , Le Conte Yves
Published: March 2003

Abstract The parasitic mite Varroa destructor Anderson & Trueman is a major pest of the honeybee Apis mellifera L. throughout the world. Chemical agents currently used for mite control leave contaminating residues and promote pesticide resistance. As an alternative means of control, it would be useful to identify natural substances enabling bees to detect Varroa inside brood cells. These substances could then be used to trigger mite hygienic behaviour by bees.

In this study several techniques were used to screen substances that might allow detection of infested brood cells by bees. Gas chromatography‐mass spectrometry analysis was performed on substances extracted in dichloromethane from the contents of brood cells. Solid phase microextraction and solid injection were performed on substances obtained from living and dead Varroa, respectively. Electroantennography was performed to assess the sensitivity of olfactory receptors in bee antennae to some of these substances.

Principal component analysis based on proportions of cuticular substances allowed discrimination between bees and other cell contents. Foundress Varroa exhibited the greatest dissimilarity to healthy pupae that were used as controls. Immature Varroa and faecal material were intermediate. High molecular weight compounds, mainly dimethylalkanes, were proportionally the most characteristic components of foundress Varroa. This finding suggests that these compounds would be the most apt to induce uncapping of cells infested by Varroa. Solid‐phase microextraction and solid injection demonstrated the presence of aliphatic acids, esters, and one alcohol, eicosenol, in Varroa. Electroantennographic recordings showed that mite‐resistant bees were more responsive to some acids and one ester. We speculate that these compounds may be involved in recognition of living Varroa by honeybees.
More than a 600‐fold variation in nitrogen dioxide assimilation among 217 plant taxa
Authors: Morikawa H. , Higaki A. , Nohno M. , Takahashi M. , Kamada M. , Nakata M. , Toyohara G. , Okamura Y. , Matsui K. , Kitani S. , Fujita K. , Irifune K. , Goshima N.
Published: March 2003

Assimilation of nitrogen dioxide in response to fumigation with 15N‐labelled nitrogen dioxide was studied in 217 plant taxa. The taxa included 50 wild herbaceous plants collected from roadsides (42 genera, 15 families), 60 cultivated herbaceous plants (55 genera, 30 families) and 107 cultivated woody plants (74 genera, 45 families). Two parameters, the ‘NO2‐N content’, or NO2‐derived reduced nitrogen content in fumigated plant leaves (mg N g–1 dry weight), and the ‘NO2‐utilization index’, or percentage of the NO2‐derived reduced nitrogen in the total reduced nitrogen, were determined. The NO2‐N content differed 657‐fold between the highest (Eucalyptus viminalis; 6·57) and lowest (Tillandsia ionantha and T. caput‐medusae; 0·01) values in the 217 taxa; 62‐fold in a family (Theaceae) and 26‐fold in a species (Solidago altissima). Nine species had NO2‐utilization indices greater than 10%, of which Magnolia kobus, Eucalyptus viminalis, Populus nigra, Nicotiana tabacum and Erechtites hieracifolia had NO2‐N contents > 4·9. These plants can be considered ‘NO2‐philic’ because in them NO2‐nitrogen has an important function(s). The Compositae and Myrtaceae had high values for both parameters, whereas the monocots and gymnosperms had low ones. These findings suggest that the metabolic pathway of NO2‐nitrogen differs among plant species. The information presented here will be useful for creating a novel vegetation technology to reduce the atmospheric concentration of nitrogen dioxide.
Low growth temperature‐induced changes to pigment composition and photosynthesis in Zea mays genotypes differing in chilling sensitivity
Authors: Haldimann P.
Published: March 2003

The effects on pigment composition and photosynthesis of low temperature during growth were examined in the third leaf of three chilling‐tolerant and three chilling‐sensitive genotypes of Zea mays L. The plants were grown under a controlled environment at 24 or 14 °C at a photon flux density (PFD) of 200 or 600 μmol m–2 s–1. At 24 °C, the two classes of genotypes showed little differences in their photosynthetic activity and their composition of pigments. At 14 °C, photosynthetic activity was considerably reduced but the chilling‐tolerant genotypes displayed higher photosynthetic rates than the chilling‐sensitive ones. Plants grown at 14 °C showed a reduced chlorophyll (Chl) a + b content and a reduced Chl a/b ratio but an increased ratio of total carotenoids to Chl a + b. These changes in pigment composition in plants grown at low temperature were generally more pronounced in the chilling‐sensitive genotypes than in the tolerant ones, particularly at high PFD. Furthermore, at 14 °C, all the genotypes showed increased ratios of lutein, neoxanthin and xanthophyll‐cycle carotenoids to Chl a + b but a reduced ratio of β‐carotene to Chl a + b, especially at high PFD. At 14 °C, the chilling‐tolerant genotypes, when compared with the sensitive ones, were characterized by higher contents of β‐carotene and neoxanthin, a lower content of xanthophyll‐cycle carotenoids, a lower ratio of xanthophylls to β‐carotene, and less of their xanthophyll‐cycle carotenoid pool in the form of zeaxanthin. These differences between the two classes of genotypes were more pronounced at high PFD than at low PFD. The results are discussed in terms of the relationship that may exist in maize between pigment composition and the capacity to form an efficient photosynthetic apparatus at low growth temperature.
Effects of long‐term elevated [CO2] from natural CO2 springs on Nardus stricta: photosynthesis, biochemistry, growth and phenology
Authors: Cook A. C. , Tissue D. T. , Roberts S. W. , Oechel W. C.
Published: March 2003

Plants of Nardus stricta growing near a cold, naturally emitting CO2 spring in Iceland were used to investigate the long‐term (> 100 years) effects of elevated [CO2] on photosynthesis, biochemistry, growth and phenology in a northern grassland ecosystem. Comparisons were made between plants growing in an atmosphere naturally enriched with CO2 (≈ 790 μmol mol–1) near the CO2 spring and plants of the same species growing in adjacent areas exposed to ambient CO2 concentrations (≈360μmol mol–1). Nardus stricta growing near the spring exhibited earlier senescence and reductions in photosynthetic capacity (≈25%), Rubisco content (≈26%), Rubisco activity (≈40%), Rubisco activation state (≈23%), chlorophyll content (≈33%) and leaf area index (≈22%) compared with plants growing away from the spring. The potential positive effects of elevated [CO2] on grassland ecosystems in Iceland are likely to be reduced by strong down‐regulation in the photosynthetic apparatus of the abundant N. stricta species.
Physiological, stomatal and ultrastructural ozone responses in birch (Betula pendula Roth.) are modified by water stress
Authors: Pääkkönen E. , Vahala J. , Pohjola1 M. , Holopainen T. , Kärenlampi L.
Published: March 2003

The physiological, stomatal and ultrastructural responses to ozone and drought of ozone‐sensitive and more ozone‐tolerant birch (Betula pendula Roth.) clones were studied singly and in combination, in a high‐stress chamber experiment and in a low‐stress open‐field experiment. In the chamber experiment, well watered (WW), moderately watered (MW) or drought‐stressed (DS) saplings were exposed for 36 d to 0 or 130 nmol mol∠1 ozone. In the open‐field experiment, well watered or drought‐stressed saplings were grown for one growing season in ambient air or exposed to 1·8 × ambient ozone. Drought stress reduced growth rate, stomatal conductance, stomatal density and the proportion of starch and thylakoids in chloroplasts, but stimulated net photosynthesis, Rubisco and chlorophyll quantity at the end of the growing season, and increased the size and density of plastoglobuli. Ozone fumigations caused more variable, clone‐ and exposure‐dependent responses in growth, decreased stomatal conductance and net photosynthesis, an increased number of stomata, visible and ultrastructural chloroplast injuries, and enhanced autumn yellowing of the leaves. Ozone‐induced changes in plastoglobuli, starch and thylakoids resembled drought responses. The two experiments revealed that, depending on the experimental conditions and the variable, the response to drought and ozone stress can be independent, additive or interactive. Drought protected the plants from ozone injuries under high‐stress conditions in the chamber experiment. In the low‐stress, open‐field experiment, however, enhanced ozone damage was observed in birch saplings grown under restricted water supply.
Water uptake and structural plasticity along roots of a desert succulent during prolonged drought
Authors: North G. B. , Nobel P. S.
Published: March 2003

Desert succulents resume substantial water uptake within 1–2 d of the cessation of drought, but the changes in root structure and hydraulic conductivity underlying such recovery are largely unknown. In the monocotyledonous leaf succulent Agave deserti Engelm. substantial root mortality occurred only for lateral roots near the soil surface; nearly all main roots were alive at 180 d of drought. New main roots were initiated and grew up to 320 mm at soil water potentials lower than – 5·0 MPa, utilizing water from the shoot. The hydraulic conductivity of distal root regions decreased 62% by 45 d of drought and 70% thereafter. After 7 d of rewetting, root hydraulic conductivity was restored following 45 d of drought but not after 90 and 180 d. The production of new lateral roots and the renewed apical elongation of main roots occurred 7–11 d after rewetting following 180 d of drought. Hydraulic conductivity was higher in the distal region than at midroot and often increased again near the root base, where many endodermal cells lacked suberin lamellae. Suberization and xylem maturation were influenced by the availability of moisture, suggesting that developmental plasticity along a root allows A. deserti to capitalize on intermittent or heterogeneous supplies of water.
Perturbation in leaves of salt‐treated Sorghum: elements for interpretation of the normal development as an adaptive response
Authors: Amzallag G. N. , Seligmann H.
Published: March 2003

Developmental windows are specific periods of sensitivity in which a perturbation may be adaptively integrated. In Sorghum bicolor, two developmental windows which enable adaptive adjustment to salinity (increase in tolerance) have been described during vegetative development. A third developmental window is open during the transition between vegetative and reproductive development. This third developmental window was analysed using morphological markers (specific malformations on leaves), and their relationship with vegetative and reproductive events. A positive link was observed between fertility and malformations on the last leaf. We concluded that this late window enables an adaptive adjustment of reproductive development, counteracting the negative effect of salt adaptation on fertility. Developmental windows open following rapid changes in growth of the different organs. They permit adaptive adjustments to emergence or senescence of various organs. This phenomenon is integrated within normal development, but developmental windows are enlarged for plants exposed to perturbation and for their progeny.
Temporal course of graviperception in intermittently stimulated cress roots
Authors: Hejnowicz Z. , Sondag C. , Alt W. , Sievers A.
Published: March 2003

Gravitropic bending of Lepidium roots caused by intermittent stimulation lasting ≈ 1 h was the same for a particular sum of stimulation intervals and was independent of (i) the length of a single stimulation interval (from 1 to 12·2 s) during which the roots were exposed unilaterally and horizontally, and (ii) rest intervals (from 60 to 300 s) during which roots were horizontally rotated at two revolutions per minute on a clinostat. The same effectiveness of equal sums of short stimulations separated by relatively long rest intervals indicates that the signals into which the stimuli are transduced are: (i) additive; (ii) proportional to the duration of a single stimulation; and (iii) stable for at least 5 min. The perception time is shorter than 1 s, the presentation time is ≈ 10 s. The effects of intermittent stimulation fit the hypothesis that the gravity‐induced movement of statoliths changes asymmetrically the stress in cytoskeletal actin filaments, thereby inducing gravitropic bending.