bluuebunny/crossref_metadata_2025 huggingface dataset:
Is birthweight a good marker for gestational exposures that increase the risk of adult disease?
Authors: Morley Ruth , Owens Julie , Blair Eve , Dwyer Terence
Published: March 2003

There is much evidence of a link between low birthweight and elevated risk of adult cardiovascular disease, from humans and experimental animals. However, if one relies on data linking birthweight to coronary heart disease to estimate the public health implications of this association, the effects are likely to be modest. The focus on birthweight may be misplaced, because reduced size at birth may not be in the causal pathway linking gestational factors to disease in adult offspring. We need to know more about this before we can estimate the public health implications of gestational factors and assess the potential for intervention. The most studied gestational factor is maternal nutrition. We review here evidence for and against birthweight being in the causal pathways between suboptimal maternal nutrition and increased risk of adult disease in the offspring and provide evidence suggesting that birthweight is not in all of them. From a public health point of view, we suggest that future research in this field should focus on modifiable gestational exposures that may be linked to adult disease, whether or not they influence size at birth.
Prevalence of intellectual disability in Western Australia
Authors: Leonard Helen , Petterson Beverly , Bower Carol , Sanders Richard
Published: March 2003

Record linkage of multiple sources was used to ascertain children with intellectual disability born in Western Australia between 1983 and 1992. The prevalence was 14.3 per 1000, 10.6 per 1000 for children with mild or moderate and 1.4 per 1000 for those with a severe level of intellectual disability. Prevalence was greater in males (prevalence ratio 1.6) and in children of Aboriginal mothers (prevalence ratio 2.3). Although prevalence of intellectual disability has been found to vary according to study location, method of ascertainment and criteria used, these estimates are similar to estimates from several recent studies.
Interferon production by Theileria annulata‐transformed cell lines is restricted to the beta family
Authors: SAGER HEINZ , BRUNSCHWILER CHRISTELLE , JUNGI THOMAS W.
Published: March 2003

Theileria are tick‐transmitted protozoans causing often fatal diseases in ruminants. Theileria sporozoites immortalize and transform host cells of haematopoietic origin. Transformation is associated with profound functional alterations. For example, bovine cells infected by Theileria annulata or T. parva. constitutively produce interferon (IFN). In this study, the type and family of IFN produced by a panel of T. annulata‐transformed cell lines and a T. parva‐transformed cell line was investigated, using molecular probes specific for the members of the IFN‐α, IFN‐β, IFN‐γ and IFN‐ω family. T. parva‐transformed cells produced IFN‐γ exclusively, whereas T. annulata‐infected cells expressed type I IFN only. Analysis of mRNA expression showed that this type I IFN was confined to IFN‐β, regardless of the cellular origin of the transformed cells. When cells were exposed to double‐stranded RNA (poly (I:C)) which induces IFN production in other systems, a 10–5,000fold increase in IFN activity was noted. The amounts of IFN‐β mRNA were inceased, but mRNA coding for IFN‐α, IFN‐ω or IFN‐γ was not detected. In contrast, primary macrophages, from which many of the tested lines were derived, expressed IFN‐α, IFN‐β and IFN‐ω mRNA to similar degrees when stimulated by LPS or poly (I:C). Thus, T. annulata appears to constitutively turn on IFN‐β gene transcription while silencing the genes coding for IFN‐α and IFN‐ω.
Identification of Neospora antigens recognized by CD4+ T cells and immune sera from experimentally infected cattle
Authors: MARKS JOANNE , LUNDÉN ANNA , HARKINS DAVID , INNES ELISABETH
Published: March 2003

Neospora caninum is recognized as a major cause of infectious abortion in cattle. Very little is known about immunity to Neospora. Cell mediated responses have previously been shown to be important in the development of protective immunity to the closely related parasite Toxoplasma gondii, and may therefore be an important component in the immune response to Neospora. In this paper we report that a group of low molecular weight NC1 strain tachyzoite antigens (≤ 30 kDa) separated by SDS PAGE and bound to nitrocellulose membrane stimulated proliferation in vitro of CD4+ T cells from calves experimentally infected with N. caninum. Proliferation was accompanied by production of high concentrations of IFNγ. Several of these antigens were also recognized by antibody produced in these animals. As the most effective vaccines require the stimulation of both humoral and cell mediated immune responses, these antigens may be important in the development of a vaccine against neosporosis.
Identification, characterization and expression of Toxocara canis nematode polyprotein allergen TBA‐1
Authors: YAHIRO SHINICHIRO , CAIN GEORGE , BUTLER JOHN E.
Published: March 2003

We have cloned the cDNA of TBA‐1, the Nematode polyprotein allergen (NPA) of Toxocara canis and found it to be most similar to ABA‐1, the Ascaris NPA, on the basis of amino acid sequence. We could study the antigenic properties of an E‐coli synthesized fusion protein prepared with the cloned gene since no glycosylation site was expected from the deduced amino acid sequence. Although no IgE responses to TBA‐1 were detected, recombinant TBA‐1 was differently recognized by serum IgG antibodies when the recombinant TBA‐1 was directly adsorbed vs when immobilized via a streptavidin linkage on polystyrene microtitre wells. One group of sera recognized TBA‐1 directly immobilized while the second only recognized TBA‐1 immobilized via streptavidin linkage. The former were from rodents immunized with a Toxocara sp. adult worm extract while the latter were obtained from rodents infected with T. canis larva or immunized with a Anisakis simplex L3 larval extract. These observations suggest that the two in vivo forms of TBA‐1 are expressed, but during different stages of the parasite's life cycle.
Serum concentrations of sICAM‐1, sE‐, sP‐ and sL‐selectins in patients with Schistosoma mansoni infection and association with disease severity
Authors: ESTERRE  , RAOBELISON  , RAMAROKOTO  , RAVAOALIMALALA  , BOISIER  , ROUX
Published: March 2003

Increased serum concentrations of soluble intercellular adhesion molecule‐1 (sICAM‐1, CD54) and of soluble E‐ (CD62E), but not soluble P‐ (CD62P) and L‐ (CD62 L) selectins, were detected in Malagasy patients living in an hyperendemic focus of Schistosoma mansoni. Levels of sICAM‐1 remained elevated for several months after treatment with praziquantel. Serum levels of ICAM‐1, but not of other markers, were significantly correlated with the disease severity, as indicated by ultrasonographical data, and with some circulating fibrosis markers (at least hyaluronic acid). sICAM‐1 level may reflect endothelial inflammatory reactions, probably harmful, in the liver and may be useful for monitoring morbidity evolution in schistosomiasis mansoni.
Immunological properties of recombinant proteins of the transmission blocking vaccine candidate, Pfs48/45, of the human malaria parasite Plasmodium falciparum produced in Escherichia coli
Authors: MILEK RICHARD L.B. , ROEFFEN WILL F.G. , KOCKEN CLEMENS H.M. , JANSEN JOSEPHINE , KAAN ANITA M. , ELING WIJNAND M.C. , SAUERWEIN ROBERT W. , KONINGS RUUD N.H.
Published: March 2003

A precondition for the development of a transmission blocking vaccine based on the sexual stage‐specific surface antigen Pfs48/45 of Plasmodium falciparum is its heterologous synthesis in a native state. Here we describe the production of recombinant Pfs48/45 in Escherichia coli. Two recombinant proteins, of which one is a glutathione‐S‐transferase fusion protein, were produced. Enzyme‐linked immunosorbent assays showed that at least a subfraction of the recombinant proteins had a conformation capable of binding transmission blocking monoclonal antibodies. However, despite the fact that both proteins were very immunogenic, they did not induce transmission blocking immunity in mice or rabbits. Immunological studies with congenic mouse strains demonstrated that immune responses could be boosted with gametocyte extracts and were not restricted to a particular class II major histocompatibility complex haplotype.
A comparison of re‐infection rates with Schistosoma haematobium following chemotherapy in areas with high and low levels of infection
Authors: MUTAPI  , NDHLOVU  , HAGAN  , WOOLHOUSE
Published: March 2003

Two groups of children (6–15 years) from a Schistosoma haematobium endemic area were followed for 9 months after praziquantel treatment. Seventy‐three children came from an area of high infection while 67 children came from an area of low infection. Pre‐treatment infection prevalence in the high infection area (76.6%) was significantly higher than that in low infection area (36.3%). Levels of anti‐SEA immunoglobulin (Ig)A and IgM were significantly higher and levels of IgG3 significantly lower in children from the low infection area. Nine months after treatment, infection prevalence was significantly higher in the high infection area (29.0%) (where re‐infection rates were higher) than in the low infection area (12.9%). Children from the high infection area were six times more likely to get re‐infected than those from the low infection area, while younger children were 30 times more likely to get re‐infected than older children. These results are discussed in relation to differences in transmission and the development of acquired immunity. Pre‐treatment levels of IgM and the difference between IgE and IgG4 were positively associated with re‐infection in the high infection area. These results are discussed in relation to the interpretation of simple correlations between infection and some antibody levels and the inference of causal relationships between observed epidemiological and immunological patterns.
Experimental investigations on the B and T cell immune response in primary alveolar echinococcosis
Authors: Bauder  , Auer  , Schilcher  , Gabler  , Romig  , Bilger  , Aspöck
Published: March 2003

Susceptibility/resistance of the intermediate host to alveolar echinococcosis (AE) seems to be based on hitherto unknown immunological mechanisms, possibly involving the activation of different CD4+ T cell immune responses (Th1/Th2). Mice of two strains previously characterized as ‘susceptible’ (C57BL/6 J) and ‘resistant’ (C57BL/10 J) to secondary AE were orally infected with eggs of Echinococcus multilocularis and the course of infection was analysed by macroscopical, pathohistological and immunohistochemical examinations of the lymphocytes and cytokines participating in the periparasitic granulomas and by serological examinations of cytokines and E. multilocularis‐specific antibodies. Although differences in the extent of parasitic growth were seen between the two groups, the composition of the granulomas was quite similar with CD4+ cells being the dominant lymphocyte subpopulation, succeeded by B cells and CD8+ cells. Interferon (IFN)‐γ‐, interleukin (IL)‐2‐ and IL‐4‐expressing cells could not be detected in the lesions of the early phase of the infection, possibly indicating the host's immunosuppression, but were present at the end. IL‐10 was the most prominent cytokine throughout the course of the disease. Serological analyses of the cytokine concentrations revealed small amounts at the beginning and high levels at the end of the infection. The pattern of cytokine response was similar for IL‐4 in both strains, but different for IL‐2 and IL‐10 in the late phase, when the C57BL/10 J strain developed higher levels than the C57BL/6 J strain. Correspondingly only small amounts of immunoglobulin (Ig)M, IgG1, IgG2a and IgG3 could be detected at the beginning of disease, followed by higher levels at the end. The courses of antibody titres were similar in both groups except IgG3, which was more pronounced in the C57BL/10 J strain. Parasite‐specific IgG2b could neither be detected in the C57BL/6 J nor in the C57BL/10 J strain by the test system used. The results of the study suggest both subsets of CD4+ T cells (Th1 and Th2) being involved in murine primary alveolar echinococcosis. A strict differentiation of mice in susceptible and resistant animals based on the activation of different CD4+ T cell immune responses (Th1 ‘resistant’ and Th2 ‘susceptible’) should be avoided.
Interferon‐γ‐independent CD8+ T cell‐mediated protective anti‐malaria immunity elicited by recombinant adenovirus
Authors: Rodrigues  , Claassen  , Lee  , Wilson  , Nussenzweig  , Tsuji
Published: March 2003

Recombinant adenovirus, expressing the CS protein of Plasmodium yoelii, AdPyCS, was shown to induce a comparable degree of T cell‐mediated protection against malaria as a single dose of irradiated P. yoelii sporozoites, causing inhibition of liver stage development. We now report that differently from sporozoite‐induced immunity, interferon (IFN)‐γ does not mediate the protective immunity induced by AdPyCS, since a similar degree of protection was observed in AdPyCS immunized mice lacking IFN‐γ−/− and the IFN‐γ receptor (IFN‐γR−/−) compared to that in wild‐type mice. Depletion of CD8+ T cells from these immunized mice almost completely abolished the AdPyCS‐induced immunity, indicating that the immunization with AdPyCS induces CD8+ T cell‐mediated protective anti‐malaria immunity, which is independent of IFN‐γ.
Humoral immune responses during a malaria vaccine trial in Tanzanian infants
Authors: Galindo  , Acosta  , Schellenberg  , Aponte  , Roca  , Oettli  , Urassa  , Armstrong Schellenberg  , Kahigwa  , Ascaso  , Mshinda  , Lwilla  , Vidal  , Menendez  , Tanner  , Alonso
Published: March 2003

The development of a malaria vaccine is a priority for improved and sustained malaria control. Optimal use of a vaccine in Africa will only be achieved if it can be delivered through the Expanded Programme of Immunization (EPI). We have completed a trial of the peptide vaccine SPf66 in Tanzanian infants, given alongside the EPI vaccines. This paper describes the humoral responses to SPf66 and the EPI vaccines. A total of 1207 infants were recruited into a two‐arm, double‐blind, individually randomized placebo‐controlled trial of SPf66. The objectives of the trial were to determine the safety, immunogenicity and efficacy of SPf66 and to assess interactions with EPI vaccines when three doses of SPf66 were delivered alongside the EPI vaccines. Cross‐sectional surveys were carried out to asses seroconversion rates to the EPI vaccines and the antibody response to SPf66 (NANP)50 and Plasmodium falciparum lysates. Seroconversion rates to EPI vaccines were high and no statistically significant differences in prevalence or titres were found between SPf66 and placebo recipients. IgG antibodies against SPf66 (NANP)50 and whole P. falciparum lysate were present in high titres in mothers of recruited children at the time of birth. Vaccination with SPf66 stimulated a good anti‐SPf66 IgG response which declined to preimmunization levels by 2 years of age and which was not associated with protection against clinical malaria. The vaccine induced no IgG antibodies against (NANP)50 or P. falciparum lysates. SPf66 stimulated a humoral immune response when given to very young infants and did not interfere with seroconversion to EPI vaccines. The response to SPf66 was qualitatively different from that seen in older children, in whom SPf66 has been shown to be moderately efficacious. This difference raises concerns about the difficulties of immunizing very young infants who need to be targeted by antimalarial vaccination programs.
Contribution of C5‐mediated mechanisms to host defence against Echinococcus granulosus hydatid infection
Authors: Ferreira Ana María , Breijo Martín , Sim Robert B. , Nieto Alberto
Published: March 2003

The aim of this work was to investigate the contribution of complement C5‐mediated mechanisms, with an emphasis on inflammation, to host defences against Echinococcus granulosus hydatid disease. Thus, we compared the systemic and local inflammatory responses induced by the parasite, and the outcome of infection, between congenic C5‐sufficient (B10.D2 n/SnJ) and C5‐deficient (B10.D2 o/SnJ) mice challenged with protoscoleces. Indirect evidence of in‐vivo complement activation during the establishment phase was obtained; infection induced serum amyloid P and eosinophil responses which were dependent on C5. Early recruitment of polymorphonuclear cells was not dependent on the presence of C5. The higher capacity of C5‐sufficient mice to recruit eosinophils was also observed during the cystic phase of infection, and mice recruiting more eosinophils developed lower parasite masses. Analysis of the outcome of infection after 8 months showed that C5‐sufficient mice were more resistant to infection than C5‐deficient mice in terms of individuals with no cysts; this trend was not statistically significant. In addition, C5‐deficient mice developed higher numbers of large (> 5 mm in diameter) cysts and higher cyst weights than C5‐sufficient mice indicating that C5‐mediated mechanisms are detrimental for parasite growth. Taken together, our results suggest that complement, through C5‐mediated effectors, contributes to host defences by both restricting the establishment of infection and controlling the growth of established cysts. This contribution may, at least partially, be associated with the ability of C5a to promote eosinophil infiltration.
IFN‐γ gene therapy by intrasplenic hepatocyte transplantation: a novel strategy for reversing hepatic fibrosis inSchistosoma japonicum‐infected mice
Authors: Zhang Lihuang , Mi Jing , Yu Yizhi , Yao Hangping , Chen Hong , Li Mingwei , Cao Xuetao
Published: March 2003

Liver‐targeted gene therapy using hepatocyte as recipient cells has recently been documented to be effective in treatment of numerous hepatic diseases, such as metabolic diseases and liver carcinoma. IFN‐γ elicits antipreliferative and antifibrogenic activity in a variety of mesenchymal cells, including hepatic satellite cells. To investigate the antifibrogenic response of liver gene therapy mediated by intrasplenic transplantation of gene‐modified hepatocytes, normal mouse liver cell line BNL CL.2 cells were transfected with murine IFN‐γ gene (BNL.IFN‐γ)in vitro, and transplanted intrasplenically intoSchistosoma japonicum‐infected mice. The amounts and distribution of IFN‐γ (which inhibits collagen synthesis), TGF‐β (which stimulates collagen synthesis) and extracellular matrix, including type I and III collagen, were detected. In mice infected withS. japonicumand then treated with BNL.IFN‐γ, an increase of IFN‐γ and decrease of TGF‐β1were detected at 20 weeks postinfection compared to untreatedS. japonicum‐infected mice. Immunohistochemical analysis showed thatS. japonicuminfection induced a marked increase of type I and III collagen synthesis. Whereas, 4 weeks after treatment with BNL.IFN‐γ, net synthesis rates of type I and III collagen were markedly decreased in the liver of infected mice. In addition, a decreased expression of TGF‐β1and its receptor TGF‐βRII in the liver of BNL.IFN‐γ‐treated mice was also observed. Moreover, the decrease in TGF‐β1and TGF‐βRII protein approximately paralleled the decrease in their mRNA expression, which was detected by RNA dot blotting. The data indicate that intrasplenic transplantation of IFN‐γ gene‐modified hepatocyte can be a candidate approach to treat hepatic fibrosis.
Oestrus ovis (Diptera: Oestridae): effects of larval excretory/secretory products on nitric oxide production by murine RAW 264·7 macrophages
Authors: Tabouret G. , Vouldoukis I. , Duranton C. , Prevot F. , Bergeaud J.P. , Dorchies P. , Mazier D. , Jacquiet P.
Published: March 2003

Larvae of Oestrus ovis (Insecta: Diptera: Oestridae) are common parasites of nasal and sinus cavities of sheep and goats. Previous studies revealed that crude extracts of larvae modify NO synthesis by ovine monocyte derived macrophages. The aim of this study was to investigate the larval excretory/secretory products effects on nitric oxide production by murine tumour macrophages RAW 264·7. Stimulation of RAW macrophages by excretory/secretory products of the three instars larvae (25 µg/ml) significantly increased nitrite concentrations in culture supernatants compared to negative and positive Escherichia lipopolysaccharide control. This effect was time and dose dependent. Nitrite production in culture supernatants was due to induction of isoform NOS‐2 because both NG monomethyl l‐arginine (100 µm) and dexamethasone (20 µm) inhibited, by 60 and 50%, respectively, nitrite accumulation in culture supernatants. First steps of purification, by ion exchange chromatography, indicated that one protein of 29 kDa was able to induce NO synthesis by macrophages. Further studies are needed for a better characterization of these molecule and to investigate their immunogenicity for a vaccine approach.
The age‐related immunity in cattle to Babesia bovis infection involves the rapid induction of interleukin‐12, interferon‐γ and inducible nitric oxide synthase mRNA expression in the spleen
Authors: Goff Will L. , Johnson Wendell C. , Parish Steven M. , Barrington George M. , Tuo Wenbin , Valdez Reginald A.
Published: March 2003

Young calves possess a strong innate immunity against Babesia bovis infection that lasts for approximately 6 months after birth and is abrogated with the removal of the spleen. This immunity is characterized as cellular involving a soluble mediator. Nitric oxide has been implicated by virtue of its babesiacidal affects in vitro, but questioned to be as effective in vivo, due to its ability to downregulate type‐1 immunity. Spleen cells were obtained from 4‐month‐old calves and adult steers and processed for monitoring cytokine and inducible nitric oxide synthase (iNOS) mRNA expression during the response to initial B. bovis infection. The data provided evidence of a transient role for nitric oxide in innate immunity, characterized by brief iNOS induction in the spleen of calves that was not detectable in the spleens of adults. The iNOS message followed the early induction of interleukin (IL)‐12 and interferon (IFN)‐γ message in calves. The induction of IL‐12 and IFN‐γ message in adults was delayed until IL‐10 message was induced. Transformation growth factor‐β mRNA expression levels were greater in spleen cells from adults early in infection and then declined, whereas expression levels increased in spleen cells from calves later in the infection process. Together, the data support the concept of ‘first come, first serve’ cytokine influence over cellular activities, the importance of a type‐1 response in the control of an initial infection and the need for tight regulation in order to prevent pathology associated with over production of nitric oxide and inflammatory cytokines.
Maxadilan, the vasodilator/immunomodulator from Lutzomyia longipalpis sand fly saliva, stimulates haematopoiesis in mice
Authors: Guilpin Valerie O. , Swardson‐Olver Christine , Nosbisch Leanna , Titus Richard G.
Published: March 2003

Protozoal parasites of the genus Leishmania are transmitted to their vertebrate host within the saliva of the sand fly during a blood meal. The saliva of the sand fly Lutzomyia longipalpis contains maxadilan, a potent vasodilator and immunomodulator. Maxadilan has been shown to enhance the virulence of L. major in all strains of laboratory mice when injected along with the organism. Increased haematopoiesis has been associated with enhanced susceptibility to Leishmania organisms. Here, we show that maxadilan alone stimulates bone marrow haematopoiesis through its ability to stimulate interleukin‐6 production by bone marrow stromal cells. Moreover, these effects of maxadilan are mediated through the interaction of maxadilan with the pituitary adenylate cyclase activating polypeptide receptor. These data suggest that increasing haematopoiesis may be yet another way that maxadilan enhances susceptibility of mice to Leishmania infection.
Antennal contact chemosensilla in Psylliodes chrysocephala responding to cruciferous allelochemicals
Authors: ISIDORO N. , BARTLET E. , ZIESMANN J. , WILLIAMS I. H.
Published: March 2003

Sensilla chaetica, which protrude above all other sensilla on the antenna of Psylliodes chrysocephala L., the cabbage stem flea beetle, were investigated ultrastructurally and found to be innervated by five to six sensory neurones. A dendrite from one of these neurones terminates in a tubular body at the shaft base, whereas dendrites from the others run unbranched to a pore at the shaft tip. Such a structure typifies a sensillum with a combined gustatory/mechanosensory function. Electrophysiological recordings using the tip‐recording technique confirmed that this sensillum contains one mechanosensory cell and several chemosensory cells. The chemosensory cells were responsive to host plant chemicals. Sensilla chaetica were also found to be responsive to glucosinolates. One of the sensilla chaetica emerges from a domed area of cuticle on antennomere six. This was found to be relatively less responsive to the chemical stimuli tested and more responsive to mechanical stimulation. It is suggested that the sensilla chaetica are contact chemosensilla, that respond to chemicals present in plant surface waxes when P. chrysocephala antennates a leaf.
Differences in adipokinetic response of Pyrrhocoris apterus (Heteroptera) in relation to wing dimorphism and diapause
Authors: Socha R. , Kodrík D.
Published: March 2003

Three experimental groups of adult females (reproductive and diapausing brachypters, and macropters with reproductive arrest) of Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) from a temperate population were analysed for their adipokinetic responses. The adipokinetic response, expressed as an increase of haemolymph lipids after injection of adipokinetic hormone from Locusta migratoria (Lom‐AKH‐I), was assessed in relation to age, wing dimorphism and type of reproductive arrest. Two pmols of Lom‐AKH‐I were used for determination of adipokinetic responses. The increase of haemolymph lipids in all experimental groups of females induced by this dose of the hormone was comparable with that induced by crude extract of the bug’s own corpora cardiaca. The level of adipokinetic response after injection of 2 pmol of Lom‐AKH‐I was significantly higher in macropterous and diapausing brachypterous females than in reproductive brachypterous females. However, significantly higher contents of haemolymph lipids in control macropterous females than those found in the control reproductive and diapausing brachypterous females of the corresponding age revealed wing‐morph‐related differences in lipid metabolism. The observed wing morph‐ and diapause‐related differences in the content of haemolymph lipids and adipokinetic response, respectively, are discussed in relation to the different roles of two wing morphs in the life history of this heteropteran.
Water homeostasis by wild larvae of Manduca sexta
Authors: Woods H. Arthur , Bernays E.L.izabeth A.
Published: March 2003

Modulation of faecal water loss is the principal mechanism by which larval Lepidoptera maintain water homeostasis in the laboratory. Is this also true of larvae in nature? We observed 12 fifth‐instar larvae of Manduca sexta feeding on Datura wrightii in the Sonoran Desert, U.S.A. The two main sources of water stress were: evaporative water loss across the cuticle, which appeared to be promoted by increasing body temperatures and decreasing relative humidities during daytime observation periods; and attacks by tachinid flies, which prompted caterpillars to defaecate large quantities of water and to regurgitate digestive fluid onto themselves. In both cases, caterpillars responded by producing drier faecal pellets. A subset of caterpillars consumed water‐rich flower buds of D. wrightii, which led to the production of comparatively wet faecal pellets. These data demonstrate that larval water balance in nature is affected by a variety of biotic and abiotic factors and that larvae respond to these perturbations by modulating the loss of water in the faeces.
Role of plant volatiles in host plant location of the leafminer, Liriomyza sativae (Diptera: Agromyzidae)
Authors: Zhao Yun Xian , Kang Le
Published: March 2003

Abstract The role of plant volatiles in host plant location of the leafminer Liriomyza sativae Blanchard was studied. Four types of antennal sensilla were identified on the funiculus by scanning electron microscopy: trichoid, basiconic, clavate and grooved sensilla. An olfactory pit, containing groups of sensilla, was present on the ventral side of the funiculus. No sexual difference was detected in sensilla diversity and distribution. In behavioural assays, both males and females were attracted by the odour of the bean Phaseolus vulgaris L. They had distinct EAG responses to the bean odour. No significant sexual difference was found in behaviour or EAG responses.

Electroantennograms were recorded from female L. sativae to 14 plant volatile compounds. The most distinct EAG responses were obtained for: (1) the general green leaf volatiles 1‐hexanol (E)‐2‐hexen‐1‐ol, (E)‐3‐hexen‐1‐ol and its isomers, (Z)‐3‐hexen‐1‐ol, the acetate (E)‐3‐hexenylacetate and the aldehyde hexanal; and (2) limonene, a compound associated with tomato, which is a key host plant of this insect. Other volatile compounds associated with host plants, such as α‐pinene, myrcene, β‐caryophyllene, and eugenol did not elicit responses. The ability of this insect to locate a host plant appears to be augmented by the perception of a combination of host‐specific and general green leaf volatiles. A modification of the EAG recording method of Dipteran species was provided.
Age‐dependent response of adults of a homochrome grasshopper, Oedipoda miniata, to the dark‐colour‐inducing neurohormone (DCIN) of locusts
Authors: Yerushalmi Yoram , Pener Meir Paul
Published: March 2003

Abstract The effect of the dark‐colour‐inducing neurohormone (DCIN = [His7]‐corazonin) of locusts was investigated in field‐collected young and old adults of the grasshopper, Oedipoda miniata (Pallas) (Orthoptera: Acrididae). This species shows homochromy, but neither green‐brown, nor phase‐dependent colour polymorphism. By injecting graded doses of synthetic DCIN in 2 µL of olive oil, young adults were tested within a week of their last moult, and old adults 3.5 months later, a few weeks before natural termination of their reproductive summer diapause. Colour changes were followed for 28 days after injection. Darkening of the young adults was considerable, but their response to DCIN is more moderate than that of conspecific nymphs, by exhibiting a higher threshold, slower response and weaker maximal response. Old adults also show a clear effect, but their response is even slower and less marked than the response of the young adults. It is concluded that the response to DCIN decreases from nymphs to young adults and it is further decreasing with ageing of the adults.
Cuticular hydrocarbons in a termite: phenotypes and a neighbour–stranger effect
Authors: Kaib Manfred , Franke Stephan , Francke Wittko , Brandl Roland
Published: March 2003

Abstract The composition of cuticular hydrocarbons of different colonies of the fungus‐growing termite Macrotermes falciger shows considerable intercolonial variation. Ordination, as well as cluster analyses, separate profiles into three distinct chemical phenotypes. Behavioural tests with major workers reveal no alarm behaviour or mortality in pairings of workers from the same colony but a full range from no alarm to overt aggression, with associated death, when individuals were paired from different colonies. The level of mortality increases with differences in the composition of cuticular hydrocarbons between colonies. However, no mortality occurs in pairings of individuals from neighbouring colonies belonging to different phenotypes. The data thus provide evidence for a ‘neighbour–stranger’ effect (so‐called ‘dear‐enemy’ phenomenon) in termites.
Correspondence between rates of host plant consumption and responses to the Acalymma vittatum male‐produced aggregation pheromone
Authors: Smyth Rebecca R. , Hoffmann Michael P.
Published: March 2003

Abstract In field studies, wind‐directed traps were used to investigate the resource‐based properties of the male‐produced aggregation pheromone of Acalymma vittatum (F.) (Coleoptera: Chrysomelidae). Responses to early season overwintered field‐collected male A. vittatum without food were compared with those feeding on pollen, and in turn these were compared with those feeding on cucurbit seedlings. These comparisons were modelled after transitions as they would occur at the initiation of A. vittatum host plant colonization.

In another experiment, colony‐reared male A. vittatum that had been fed only near isogenic lines of potted cucumber (Cucumis sativus) seedlings that either lacked or contained cucurbitacin were placed as bait in the traps. Using the inverse relationship, which is understood for A. vittatum, between previous exposure and the phagostimulant response to cucurbitacin, rates of foliage consumption could be manipulated. The interaction between relative rates of host plant consumption of the males used as lures and responses to the pheromone could thus be tested. The use of A. vittatum reared entirely without dietary cucurbitacin as bait also enabled evaluation of the potential role of cucurbitacin in pheromone biosynthesis. Trap responses were closely correlated with the rates of feeding of the beetles in the trap lures, but cucurbitacin was neither a precursor nor a prerequisite for the pheromone. Implications for early season field colonization and the adaptive significance of this pheromone are discussed.
Relating genotype and phenotype for tryptophan synthesis in an aphid–bacterial symbiosis
Authors: Birkle L. M. , Minto L. B. , Douglas A. E.
Published: March 2003

The symbiotic bacteria Buchnera provide their aphid hosts with tryptophan and other essential amino acids. Tryptophan production by Buchnera varied among 12 parthenogenetic clones of the pea aphid Acyrthosiphon pisum (Harris), as determined from both the incorporation of radioactivity from 14C‐anthranilate into tryptophan and the protein‐tryptophan growth rate of larval aphids on tryptophan‐free diet. The values of tryptophan production obtained for the two methods were correlated significantly with each other but not with the level of amplification of the Buchnera genes trpEG, which code for anthranilate synthase, a key enzyme in tryptophan biosynthetic pathway. This study provides the first direct demonstration of interclonal variation in production of any nutrient in an aphid–Buchnera symbiosis and indicates that a key aspect of Buchnera phenotype (tryptophan production) does not vary in a simple fashion with Buchnera genotype.
A comparison of NH4+ and NO3– net fluxes along roots of rice and maize
Authors: Colmer T. D. , Bloom A. J.
Published: March 2003

Net fluxes of NH4+ and NO3– along adventitious roots of rice (Oryza sativa L.) and the primary seminal root of maize (Zea mays L.) were investigated under nonperturbing conditions using ion‐selective microelectrodes. The roots of rice contained a layer of sclerenchymatous fibres on the external side of the cortex, whereas this structure was absent in maize. Net uptake of NH4+ was faster than that of NO3– at 1 mm behind the apex of both rice and maize roots when these ions were supplied together, each at 0·1 mol m–3. In rice, NH4+ net uptake declined in the more basal regions, whereas NO3– net uptake increased to a maximum at 21 mm behind the apex and then it also declined. Similar patterns of net uptake were observed when NH4+ or NO3– was the sole nitrogen source, although the rates of NO3– net uptake were faster in the absence of NH4+. In contrast to rice, rates of NH4+ and NO3– net uptake in the more basal regions of maize roots were similar to those near the root apex. Hence, the layer of sclerenchymatous fibres may have limited ion absorption in the older regions of rice roots.
Transformation with a gene for choline oxidase enhances the cold tolerance of Arabidopsis during germination and early growth
Authors: Alia  , Hayashi H. , Chen T. H. H. , Murata N.
Published: March 2003

We transformed Arabidopsis thaliana with the codA gene from Arthrobacter globiformis. This gene encodes choline oxidase, the enzyme that converts choline to glycinebetaine. The presence of choline oxidase and glycinebetaine in seeds of transformed lines was confirmed by Western blotting and nuclear magnetic resonance (NMR) spectrometry, respectively. The transformation with the codA gene significantly enhanced the tolerance of seeds to low temperatures, such as 0 °C, during imbibition. The transformation accelerated the germination and growth of seedlings at 10 and 15 °C. It appears that the presence of glycinebetaine in transformed plants enhances their ability to tolerate low‐temperature stress during the imbibition and germination of seeds and the growth of seedlings.
Changes of tree‐ringδ13C and water‐use efficiency of beech (Fagus sylvaticaL.) in north‐eastern France during the past century
Authors: Duquesnay A. , Bréda N. , Stievenard M. , Dupouey J. L.
Published: March 2003

We investigated variation in intrinsic water‐use efficiency during the past century by analysingδ13C in tree rings of beech growing in north‐eastern France. Two different silvicultural systems were studied: high forest and coppice‐with‐standards. We studied separately effects related to the age of the tree at the time the ring was formed and effects attributable to environmental changes. At young ages,δ13C shows an increase of more than 1‰. However, age‐related trends differ in high forest and coppice‐with‐standards. Changes in microenvironmental variables during stand maturation, and physiological changes related to structural development of the trees with ageing, could explain these results. During the past century,δ13C in tree rings shows a pattern of decline that is not paralleled by airδ13C changes. Isotopic discrimination has significantly decreased from 18·1 to 16·4‰ in high forest and varied insignificantly between 17·4 and 16·9‰ in coppice‐with‐standards. As a consequence, intrinsic water‐use efficiency has increased by 44% in high forest and 23% in coppice‐with‐standards during the past century. These results accord with the increased water‐use efficiency observed in controlled experiments under a CO2‐enriched atmosphere. However, other environmental changes, such as nitrogen deposition, may be responsible for such trends.
A mechanistic analysis of light and carbon use efficiencies
Authors: Dewar R. C. , Medlyn B. E. , McMurtrie R. E.
Published: March 2003

We explore the extent to which a simple mechanistic model of short‐term plant carbon (C) dynamics can account for a number of generally observed plant phenomena. For an individual, fully expanded leaf, the model predicts that the fast‐turnover labile C, starch and protein pools are driven into an approximate or moving steady state that is proportional to the average leaf absorbed irradiance on a time‐scale of days to weeks, even under realistic variable light conditions, in qualitative agreement with general patterns of leaf acclimation to light observed both temporally within the growing season and spatially within plant canopies. When the fast‐turnover pools throughout the whole plant (including stems and roots) also follow this moving steady state, the model predicts that the time‐averaged whole‐plant net primary productivity is proportional to the time‐averaged canopy absorbed irradiance and to gross canopy photosynthesis, and thus suggests a mechanistic explanation of the observed approximate constancy of plant light‐use efficiency (LUE) and carbon‐use efficiency. Under variable light conditions, the fast‐turnover pool sizes and the LUE are predicted to depend negatively on the coefficient of variation of irradiance. We also show that the LUE has a maximum with respect to the fraction of leaf labile C allocated to leaf protein synthesis (alp), reflecting a trade‐off between leaf photosynthesis and leaf respiration. The optimal value ofalpis predicted to decrease at elevated [CO2]a, suggesting an adaptive interpretation of leaf acclimation to CO2. The model therefore brings together a number of empirical observations within a common mechanistic framework.
Modelling the surface conductance of a broad‐leaf canopy: effects of partial decoupling from the atmosphere
Authors: Magnani F. , Leonardi S. , Tognetti R. , Grace J. , Borghetti M.
Published: March 2003

The transpiration of a mature beech (Fagus sylvatica L.) forest was measured over a whole season by the heat pulse velocity technique and the results analysed in terms of a new analytical canopy conductance model, which takes into account the effects of partial decoupling from the atmosphere on the local humidity environment experienced by the canopy. Stand daily transpiration ranged from 0·62 to 2·97 mm d–1, with a seasonal mean value of 1·97 mm d–1. Maximum canopy conductance was 18·5 mm s–1, with a mean estimated value of 5·0 mm s–1; computed values were little affected by the assumption of neutral atmospheric conditions. The decoupling coefficient Ω varied greatly on a daily and seasonal basis, with an average value of 0·28. As a result of partial decoupling, the estimated vapour pressure deficit at the notional canopy surface exceeded the values measured above the canopy by 380 Pa on average. When correctly expressed in terms of humidity at the canopy surface, the model explained 80% of the variance in half‐hourly transpiration measurements. Upon cross‐validation it still explained 72% of the variance, as compared to only 40% when correction for partial decoupling was not introduced. A baseline canopy conductance of 0·7 mm s–1, not modulated by the environment, was estimated. The implications of the model are discussed for the representation of canopy conductance and transpiration of broad‐leaf forests.
Tropic leaf movements, photosynthetic gas exchange, leaf δ13C and chlorophyll a fluorescence of three soybean species in response to water availability
Authors: Kao W.‐Y. , Tsai T.‐T.
Published: March 2003

Midday leaf angle, photosynthetic gas exchange, stable carbon isotope ratio (δ13C), and chlorophyll a fluorescence among three wild soybeans, Glycine soja, G. tomentella and G. tabacina, from habitats with different water availability were examined. Plants grown under low water availability had reduced leaf area, photosynthetic and electron transport rates, more positive δ13C values, and more vertical midday leaf angles. The three species differed in midday leaflet orientation, leaf size, photosynthesis and fluorescence responses to water availability. The species differences were consistent with the water availability of their habitat. G. soja, which grows in the wettest habitats, was shown to be the most photosynthetically susceptible to low water treatment and tended to have the most vertical midday leaflet angles. In contrast, G. tabacina, distributed in the driest habitats, had the least vertical midday leaflet angles and the lowest photosynthetic sensitivity to low water availability. G. tomentella, inhabiting an intermediate habitat, had intermediate midday leaf angles and photosynthetic responses. Our results support the hypothesis that paraheliotropic leaf movements respond in concert with photosynthetic characteristics in soybean leaves such that water use efficiency is enhanced and the risk of photoinhibition under water stress conditions is reduced.
Seasonal variation in net carbon exchange and evapotranspiration in a Brazilian rain forest: a modelling analysis
Authors: Williams M. , Malhi Y. , Nobre A. D. , Rastetter E. B. , Grace J. , Pereira M. G. P.
Published: March 2003

Tropical rain forests account for a significant fraction of global net primary productivity, and are important latent energy (LE) sources, affecting extra‐tropical atmospheric circulation. The influence of environmental factors on these fluxes has until recently been poorly understood, largely due to a paucity of data, but in recent years the amount of available data has been increased greatly by use of eddy covariance techniques. In this paper we examine the factors that control daily and seasonal carbon (C) and LE fluxes, by comparing a detailed model of the soil–plant–atmosphere continuum against a unique long‐term data‐set collected using eddy covariance at an undisturbed rain forest site north of Manaus, Brazil. Our initial application of the model was parametrized with simple measurements of canopy structure, and driven with local meteorological data. It made effective predictions of C and LE exchange during the wet season, but dry season predictions were overestimates in both cases. Sensitivity analyses indicated that the best explanation for this behaviour was a seasonal change in soil and root hydraulic resistances (Rb). An optimization routine was then used to estimate the increase in Rb during the dry season that would be required to explain the reduced dry season fluxes. The local soil, a clay latosol, is typical of much of Amazônia, having very low available water and low hydraulic conductivity. We conclude that an increase in soil–root hydraulic resistance in the dry season introduces a significant seasonal cycle to carbon and water fluxes from this tropical forest. Furthermore, our model structure appears to be an effective tool for regional and temporal scaling of C and LE fluxes, with primary data requirements being regional and temporal information on meteorology, leaf area index (LAI), foliar N, critical leaf water potentials, and plant and soil hydraulic characteristics.
Ammonium, nitrate, and proton fluxes along the maize root
Authors: Taylor A. R. , Bloom A. J.
Published: March 2003

Ion‐selective microelectrodes were used to measure NH4+, NO3–and H+fluxes along the primary root of maize seedlings. Plants were exposed to nutrient solutions containing NH4+, NO3–or both ions. Nitrogen fluxes along the root varied substantially among the different treatments. Net NH4+and NO3–uptake and H+extrusion were low at the very apex of the root and generally increased in the more basal regions. In the absence of nitrogen or in the presence of NO3–alone, net H+uptake (and root surface alkalinization) occurred at the root tip (0–1 mm), whereas net H+extrusion occurred in all other regions. In the presence of NH4+alone, a dramatic increase in net H+extrusion was detected in all regions except for the region 6–11 mm from the apex. In contrast, when NO3–alone was supplied, net H+extrusion was depressed at all locations except for the tip (0–1 mm). When both NH4+and NO3–were supplied, NO3–uptake was suppressed at all locations while net H+extrusion was increased relative to NO3–alone. The capacities to absorb NH4+and NO3–at the tip were similar, as indicated by flux rates when NH4+or NO3–were supplied as sole sources, but when supplied together, net NO3–uptake was half that of net NH4+uptake, indicating that NH4+may satisfy the nitrogen requirements of the poorly vascularized apical tissue in the most energy‐efficient way. The high spatial resolution of the measurements enabled us to establish that acidification in the root expansion zone is maintained regardless of nitrogen source.