bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibodies to a merozoite surface protein promote multiple invasion of red blood cells by malaria parasites
Authors: Ramasamy  , Yasawardena  , Kanagaratnam  , Buratti  , Baralle  , Ramasamy
Published: March 2003

The 40–50 kDa merozoite surface antigen (MSA2) is a candidate molecule for use in a malaria vaccine. The gene for MSA2 from the 3D7 isolate of Plasmodium falciparum was amplified by polymerase chain reaction and cloned into the bacterial expression vector pGEX‐3X to obtain a fusion protein of MSA2 with Schistosoma japonicum glutathione S‐transferase. The recombinant fusion protein was used to immunize rabbits. After four injections, the sera had Western blotting and immunofluorescence titres of 10−6. Immune sera, and immunoglobulin (Ig)G, F(ab)′2, F(ab) prepared from the immune sera, were assessed for their effects on the growth of 3D7 parasites in vitro by microscopy and a [3H]‐hypoxanthine incorporation assay. The antibodies did not significantly inhibit red blood cell invasion and parasite growth when added to cultures as 10% v/v serum or as immunoglobulin preparations at concentrations up to 200 μg ml−1. However, in the presence of IgG or F(ab)′2, but not F(ab), antibodies to MSA2, the proportions of red blood cells invaded by more than one merozoite increased significantly. Multiple invasion is attributed to merozoites cross‐linked by bivalent antibodies, attaching to and subsequently invading the same red cell. These observations have a bearing on the evasion of host immune responses by the parasite and the use of full‐length recombinant MSA2 protein in a malaria vaccine.
Caenorhabditis elegans as a biomonitor for immunological stress in nematodes
Authors: Nowell  , De Pomerai  , Pritchard
Published: March 2003

An experimental system has been developed using Caenorhabditis elegans (Secernentea: Rhabditida), to monitor immunological stress in nematodes. The transgenic C. elegans strain PC72 carries a lacZ reporter gene fused to a C. elegans hsp16‐1 gene, which is inducible for β‐galactosidase activity at the heat stress temperature of 26°C. The investigate the possibility of using PC72 to monitor immunological stress, its surface coat was targeted, to mimic immune attack, by raising immune sera against surface coat components selectively removed by the cationic detergent cetyltrimethylammoniunm bromide. Initially, a highly significant induction of β‐galactosidase activity was seen in PC72 incubated in either surface‐reactive or naïve rabbit serum. Complement (C3) was detected over the entire surface of adult PC72 and was thought to be responsible for stress‐induction with naïve sera. When the immunoglobulin (Ig)G fraction of naïve sera was used in isolation, no stress‐induction was seen. In contrast, a two‐fold increase in β‐galactosidase activity was seen in the presence of surface‐reactive IgG (SR‐IgG) which recognised surface components of between 6 and 40 kDa in western blot. The belief that surface reactive IgG could induce a stress response was reinforced by analysis of hsp‐16 protein expression. Cationised ferritin was then used to assess whether stress‐induction was truly a surface reactive event; binding of cationised ferritin to the nematode surface also resulted in two‐fold induction of β‐galactosidase activity. To investigate the downstream biological effects of stress induction, worm growth and fecundity were measured in the presence of IgG preparations. A significant reduction was seen in both worm length and fecundity only when larvae were incubated in surface‐reactive IgG, compared to both naïve IgG and K‐medium controls. In conclusion, it would appear that C. elegans is a suitable model to monitor the induction of immunological stress at the level of the nematode surface coat. Given the ability of nematode surface antigens to protect the vaccinated host in animal model systems, and the close phylogenetic relationships which exist between C. elegans and nematodes of medical and veterinary importance, it is conceivable that the immunological targets in or on the surface of C. elegans warrant rapid identification.
Paramyosin is a major target of the human IgA response against Schistosoma japonicum
Authors: Hernandez Maria Genevive H. , Hafalla Julius Clemence R. , Acosta Luz P. , Aligui Fe F. , Aligui Gemiliano D. , Ramirez Bernadette L. , Dunne David W. , Santiago Mario Luis
Published: March 2003

Human resistance and susceptibility to schistosomiasis is associated with age and specific antibody isotype responses against worm (SWAP) and egg (SEA) antigens. In a cross‐sectional study of 176 individuals infected with Schistosoma japonicum in the Philippines, strikingly similar isotype response patterns against SWAP and SEA was observed when compared to other endemic areas. Interestingly, IgA titres to SWAP correlated with older age among S. japonicum‐infected individuals (n = 176, P < 0.01), suggesting a role for this isotype in protective immunity. To identify the molecular targets of human IgA, 17 high‐IgA/SWAP responders were identified from the said population. IgA antibodies from the majority (14/17) of these individuals recognized a band of 97 kDa (Sj97), comigrating in immunoblots with the myofibrillar protein paramyosin. The antigen was confirmed as paramyosin by expressed sequence tag (EST)‐analysis of four clones obtained by screening an adult S. japonicum cDNA library with pooled IgA antisera and mouse antiparamyosin polyclonal antibodies. The identification of paramyosin as a major target of human IgA raises its potential as a vaccine candidate that targets mucosal immune responses. Since this antigen is exposed on the parasite surface only during the lung stages, we propose that human IgA contributes to parasite attrition during schistosome migration in the lungs.
Leucine rich repeats are the main epitopes in Leishmania infantum PSA during canine and human visceral leishmaniasis
Authors: Boceta Carolina , Alonso Carlos , Jiménez‐Ruiz Antonio
Published: March 2003

The PSA protein is one of the major antigens of the surface of the Leishmania infantum parasite membrane. We describe the immune humoral response against the PSA in dogs and human patients with visceral leishmaniasis caused by L. infantum. The immunodominant region of the PSA was determined by subcloning, expression and purification of three fragments covering the complete protein. The analysis revealed that the antibodies are mostly directed against the central region, which is formed exclusively by leucine rich repeats. This region is recognized by 100% of the sera from the infected dogs and 40% of the human sera. These percentages are significantly higher than those observed when the complete protein was used as antigen. The analysis of the isotype of the G immunoglobulins raised against the immunodominant determinants of the PSA indicates that both IgG1 and IgG2 classes are produced during natural infections but that the IgG2 predominates over that of the IgG1.
Reciprocal cross‐protection induced by sporozoite antigens SPAG‐1 from Theileria annulata and p67 from Theileria parva
Authors: Hall Roger , R.boulter Nicola , Brown C.G.duncan , Wilkie Gwen , Kirvar Erol , Nene Vish , J.musoke Anthony , J.glass Elizabeth , Morzaria Subhash P.
Published: March 2003

Theileria annulata and Theileria parva both possess a major surface antigen on the sporozoite stage of the life‐cycle, called SPAG‐1 and p67, respectively. In each case, these antigens are vaccine candidates and have been shown to induce a degree of homologous protection in earlier work. These antigens share sequence homology and are serologically cross‐reactive. Here, we confirm that these antigens confer protection against homologous species challenge. More importantly, they mutually confer a degree of cross‐species protection raising the prospect of a common vaccine in the future.
Dissociation of interleukin‐4 and interleukin‐5 production following treatment for Schistosoma haematobium infection in humans
Authors: Scott Janet T. , Turner C.michael R. , Mutapi Francisca , Woolhouse Mark E.J. , Chandiwana Steven K. , Mduluza Takafira , Ndhlovu Patricia D. , Hagan Paul
Published: March 2003

Infection with Schistosoma haematobium, the causative agent of urinary schistosomiasis is characterized by high levels of specific immunoglobulin (Ig) E and eosinophilia. The primary cytokines driving production of IgE and eosinophilia are IL‐4 and IL‐5, respectively. In this study, IL‐4 and IL‐5 production in children from a schistosome endemic area of Zimbabwe were investigated. Blood samples were taken, stimulated in vitro with either mitogen or schistosome antigens and assayed for IL‐4 and IL‐5 production. These samples produced either IL‐4 or IL‐5 but rarely both cytokines when blood was cultured in vitro for 24 or 48 h. After 72 h culture in vitro, both cytokines were detected in most samples. These data imply that while IL‐4 and IL‐5 are both produced by schistosome infected people, they are not necessarily coproduced.
Differential interleukin‐10 expression in interferon regulatory factor‐1 deficient mice during Plasmodium berghei blood‐stage infection
Authors: Tan Rosemary S.‐P. , Kara Anna U. , Feng Chiguang , Asano Yoshihiro , Sinniah Raja
Published: March 2003

Mice deficient of functional interferon regulatory factor‐1 (IRF‐1–/–) by targeted gene disruption infected with a lethal murine malaria strain, Plasmodium berghei ANKA survived longer than its wild‐type littermates despite the inability to induce appreciable amounts of interferon‐gamma (IFN‐γ) and nitric oxide. In addition, infected IRF‐1—/— mice displayed less organ injury with reduced necrosis and inflammation. Both wild‐type and IRF‐1—/— mice treated with exogenous interleukin‐12 (IL‐12) suffered extensive organ damage with corresponding up regulation of IFN‐γ, suggesting the pathogenic potential of IL‐12 and IFN‐γ. IL‐10 is a cytokine produced by CD4+ T lymphocytes belonging to the Th2 subset. Expression of IL‐10 in the wild‐type mice correlated with the severity of the infection, with higher mRNA expression towards the later stage of infection. In contrast to the wild‐type mice, IL‐10 levels in the IRF‐1–/– mice were induced early in the infection and decreased gradually as the infection progressed. Both untreated and IL‐12 treated wild‐type mice appeared to follow a Th1‐like immune response early in the infection and a Th2‐like immune response later in the infection. However, the IRF‐1–/– mice were able to launch an altered immune response with a Th2‐like immune response early in the infection. These findings suggest that IL‐10 expression in the IRF‐1–/– mice during the early stage of P. berghei ANKA infection could play an important role in suppressing pathogenic effects of a cell mediated immune response and promoting protective immunity against the parasite.
Evidence for determining parasitic factors in addition to host genetics and immune status in the outcome of murine Leishmania infantum visceral leishmaniasis
Authors: Gangneux Jean‐Pierre , Sulahian Annie , Honore Stéphanie , Meneceur Pascale , Derouin Francis , Garin Yves‐Jean‐François
Published: March 2003

C.B‐17 SCID and congenic BALB/C mice were used to examine Leishmania infantum strain pathogenicity independently of host genetic factors. While parasite loads were significantly higher in immunodeficient mice than in immunocompetent mice, the kinetics of infection during a long‐term follow‐up were similar, suggesting that intrinsic parasitic factors also influence the outcome of L. infantum infection.
Coinfection with Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis suppresses IL‐2 and IFNγ production and promotes an IL‐4 response in C3H/HeJ mice
Authors: Zeidner Nordin S. , Dolan Marc C. , Massung Robert , Piesman Joseph , Fish Durland
Published: March 2003

Previously we demonstrated that Borrelia burgdorferi transmission by Ixodes scapularis suppressed IL‐2 and IFNγ production and promoted IL‐4 production in mice. The present studies were conducted to determine whether coinfection with the human granulocytic ehrlichiosis (HE) agent would promote a Th2 cytokine response in mice. Transmission to the spleen of the agent of human granulocytic ehrlichiosis (aoHGE) and B. burgdorferi occurred 4 and 7 days, respectively, after tick infestation. Coinfection synergized to suppress splenic IL‐2 production 7–14 days after tick infestion. Transmission of B. burgdorferi or aoHGE alone significantly decreased splenic IFNγ 4–7 days after tick infestation, while coinfection suppressed IFNγ production 7–14 days after tick infestation. Splenic IL‐4 production was significantly increased 4 days after coinfection, and by day 10, aoHGE plus B. burgdorferi induced greater splenic IL‐4 (57.2 pg/ml, 348% of control values) than either organism transmitted alone (aoHGE, 22.7 pg/ml, B. burgdorferi, 25.1 pg/ml). Coinfection enhanced expansion of splenic T cells, CD4+ lymphocytes and B cells while decreasing CD8+ T cells. These data demonstrate that aoHGE and B. burgdorferi, when cotransmitted, suppress a systemic IL‐2 and IFNγ response, while strongly promoting systemic IL‐4 production in the susceptible host. The antigen(s) responsible for this polarization are unknown and will be the subject of future studies.
Leishmania immune adherence reaction in vertebrates
Authors: Domínguez Mercedes , Toraño Alfredo
Published: March 2003

In normal human blood, C3‐opsonized Leishmania promastigotes immune adhere to erythrocytes, a mechanism believed to enhance their clearance from blood and phagocytosis. Given the potential importance of this reaction in host defence against infection, the promastigote–erythrocyte interaction was studied in blood of individuals from one avian and 12 mammalian genera; [111In]‐labelled promastigotes were found to bind only to primate erythrocytes. Nevertheless, previous experiments coincubating platelets isolated from nonprimate mammals with C3‐opsonized promastigotes led to promastigote–platelet adherence. To ascertain whether this is a natural mechanism in nonprimate Leishmania infection, normal blood from members of Leishmania animal models of interest, dog, guinea‐pig, hamster, mouse and rabbit, was infected ex vivo with promastigotes. Within 1 min of blood contact, the promastigote surface was loaded with platelets, rapidly evolving into large aggregates. These results confirm the physiological nature of the reaction and demonstrate that promastigote–erythrocyte and promastigote–platelet binding are the first parasite–host cell encounters after Leishmania invasion of primates and nonprimate mammals, respectively. Leishmania immune adherence shares the characteristics of the nonanticipatory immune systems, and we consider it should be viewed as an innate vertebrate host effector mechanism.
Ultrasound hearing and male–male communication in Australian katydids (Tettigoniidae: Zaprochilinae) with sexually dimorphic ears
Authors: MASON ANDREW , BAILEY WINSTON
Published: March 2003

The genus Kawanaphila (Tettigoniidae: Zaprochilinae) is unusual among the Tettigoniidae in the possession of sexually dimorphic auditory organs. We examined the auditory system and acoustic behaviour of two previously unstudied species in this genus to test whether reduced hearing in males is consistently associated with reduced male–male competition. Kawanaphila yarraga (Rentz, 1993) and K. mirla (Rentz, 1993) are both sexually dimorphic with respect to their auditory system, but to different degrees. Males of both species produce songs consisting of trains of brief (< 1 ms) pure‐tone sound pulses at ultrasonic frequencies (K. yarraga, 40 kHz;K. mirla, 70 kHz). In both species, female hearing is more sensitive than that of males by 10 dB. In addition, male K. mirla are most sensitive at lower frequencies than females. Male and female K. yarraga differed only in sensitivity, not in tuning. The two species also differ in their degree of sexual dimorphism in auditory anatomy. Kawanaphila mirla males lack some auditory specializations of the prothoracic tracheal system, which are present in the normal tettigoniid condition in females. In K. yarraga males these structures are present, but reduced in size relative to females. The acoustic behaviour of males of the two species is consistent with this pattern of relative auditory sensitivity. Males of both species interact acoustically by altering the timing of their sound output to synchronize with neighbouring males. However, K. mirla males only interact in this way over very short distances (< 5 m), whereas K. yarraga males interact with neighbours up to at least 10 m distant. These results indicate that, although males of the two species differ in hearing sensitivity, the nature of their responses to conspecific calls are similar to one another and to those of other acoustic insects. This suggests that acoustically mediated male–male competition may be maintained even while selection favours a reduction in male auditory sensitivity.
The interaction of taste and heat on the biting response of the tsetse fly Glossina fuscipes fuscipes
Authors: VAN DER WYNAND M. , VAN NATERS GOES , DEN OTTER CORNELIS J. , CUISANCE DOMINIQUE
Published: March 2003

Abstract.Tsetse flies probe more on a heated surface with a trace of uric acid than on one without. Uric acid is one of the components of human sweat and it elicits spike responses from taste hairs on the flies' legs. In this paper it is examined how heat from the surface and taste interact to affect the biting behaviour of Glossina fuscipes fuscipes Newstead 1910 (Diptera: Glossinidae) over successive days of food deprivation. The biting behaviour consists of bouts of probing, both ambulatory and stationary, intercalated with short hops of flight. The number of bouts increases over successive days, whereas the average bout duration does not. Although uric acid alone could not induce the flies to probe, in combination with surface heat it affected the flies greatly. Average bout duration was two‐fold that on a heated surface not treated with uric acid. The frequency of bouts was not affected by uric acid. These experiments and auxiliary ones on mechanoreceptive input and odours lead to the insight that the factors which affect biting behaviour can be viewed as a hierarchy. The hierarchy extends from those that affect the onset of biting to those that affect its course.
The effect of temperature and light pulses on the induction of diapause in the Toyama strain of the Indian meal moth,Plodia interpunctella
Authors: Kikukawa Shigeru , Kubota Hideshi , Ohkouchi Hiromi , Tateiwa Kaori
Published: March 2003

Abstract.The photoperiodic response in Plodia interpunctella collected at Toyama (36.7°N) was of long‐day type and highly sensitive to temperature. The critical photoperiod giving 50% diapause was between 14 and 16 h at 20°C, between 12 and 14 h at 25°C and between 6 and 8 h at 30°C. Effects of night interruption by a 2‐h light pulse on the diapause response were examined at 25°C on different background photoperiods ranging from LD 12:12 h to LD 2:22 h. Percentage diapause was very low when the middle portion of dark period was interrupted, so that U‐ or V‐shaped response curves were obtained with background scotophases longer than 12 h. In these curves, the descending slopes were less steep than the ascending slopes. The critical dark period measured from dusk to an interrupting light pulse was about 1.5 h longer than the critical dark period (c. 10 h) in the normal photoperiodic response. The critical dark period from the interrupting light pulse to dawn, on the other hand, was not parallel to dawn but shorter than the normal critical period in LD 12:12 h and LD 10:14 h and longer than that in LD 7:17 h to LD 4:20 h, indicating that the priming effects of the light pulse might be under the influence of the photophase.
Effects of environmental factors on circadian activity in the flesh fly,Sarcophaga crassipalpis
Authors: Joplin KarL. H. , Moore Darrell
Published: March 2003

Abstract.The diel locomotor activity patterns of wandering larvae in the flesh fly, Sarcophaga crassipalpis Macquart (Diptera: Sarcophagidae), were examined using a novel apparatus and shown to be primarily diurnal, but with a minority (37%) showing nocturnal activity. In response to the environmental stress of heat shock, a significantly larger proportion (72%) of the larvae became nocturnal. In comparison, adult circadian activity also was predominantly diurnal, but not correlated with the larval activity patterns. In addition, adult patterns showed age‐related changes in entrainment and free running period. Finally, the phase of circadian‐gated adult eclosion was shown to be entrained by a 3‐day exposure to light–dark cycles delivered prior to pupariation, with the phase maintained throughout pupal–adult metamorphosis under constant dark conditions. These results demonstrate that environmental changes may have profound effects on the expression of 24‐h activity patterns and circadian rhythms during different life stages throughout development.
Green leaf volatile‐detecting olfactory receptor neurones display very high sensitivity and specificity in a scarab beetle
Authors: Hansson BilL. S. , Larsson Mattias C. , Leal Walter S.
Published: March 2003

In the Japanese scarab beetle, Phyllopertha diversa, olfactory receptor neurones specific for the detection of so‐called general green leaf volatiles (GLV) display a high specificity and sensitivity. Three main types of green‐leaf‐volatile‐detecting receptor neurones specific to (Z)‐3‐hexenyl acetate, (E)‐2‐hexenal and (Z)‐3‐hexenol, respectively, were identified. Each type responded at a very low stimulus concentration to the key stimulus, and required at least a thousand‐fold increase in concentration to respond to any of the other GLVs tested. Flower‐odour‐and pheromone‐detecting receptor neurones were also identified. Olfactory sensilla housing plant‐odour‐ or pheromone‐detecting receptor neurones displayed clear morphological differences, and were also separated into different antennal regions.
Agonistic behaviour of female Tegenaria atrica in the presence of different aged spiderlings
Authors: Pourié Grégory , Trabalon Marie
Published: March 2003

The agonistic behaviour of adult female T. atrica increases with increasing age of spiderlings until 80 days post‐emergence, then decreases. In all cases, cannibalism of spiderlings increases markedly after completion of their pre‐dispersal period with a correlation between the switch of behaviour, from tolerance to cannibalism, and a modification of individual’s cuticular compounds. Experiments that compare spiderlings weight and mobility indicate that female agonistic behaviour are always low with spiderlings in pre‐dispersal period, and high with spiderlings in post‐dispersal period. Female reproductive state and the weight/mobility of spiderlings are not the only factors controlling the adult female’s agonistic behaviour towards spiderlings on her web, as tactochemical information plays an important role in modulating agonistic behaviour after close contact between female spiders and spiderlings. The agonistic behaviour of females appears to correspond with a change in the increase of polar compound levels (methylesters and fatty acids) and the decrease of apolar compound levels (hydrocarbons) in spiderlings of different ages.
Two‐dimensional pattern discrimination by the honeybee
Authors: Horridge Adrian
Published: March 2003

For a reward of sugar, bees will learn to prefer a pattern rather than an alternative similar one. This visual discrimination allows us to measure resolution, and to search for the cues that the bees remember and later use to recognize the rewarded pattern. Two systems in parallel, analogous to low pass and high pass filters, are distinguished. The first system discriminates the location and size of at least one area of contrast on each side of the target, with inputs from blue and green receptors, but the ability to discriminate the location of colour depends upon fixation. The bees remember less than a low resolution copy of the image, even when they fixate on a vertical pattern.

The second system amplifies the contrast at edges in the pattern, ignoring the direction of contrast, and controls fixation upon the target. Edges are discriminated according to their orientation and radial or tangential arrangement. An axis of bilateral symmetry is detected. However, the relative locations of cues within the image are lost, apparently because the relevant neurones have very large fields. Only the cues, not the whole patterns, are preserved in memory. This system is colour blind because its input is restricted to the receptors with peak sensitivity in the green. The two systems together discriminate many simple patterns, but not all, because the filters are limited in variety.
Effects of ovariectomy and mating on the activity of the corpora allata in adult female Blattella germanica (L.) (Dictyoptera: Blattellidae)
Authors: Holbrook Glenn L. , Bachmann J.A.N.E. A. S. , Schal C.O.B.Y.
Published: March 2003

In adult female cockroaches, the ovary greatly affects the synthesis of Juvenile Hormone (JH) by the corpora allata, and in females of some cockroach species, removal of the ovaries results in a permanent depression of JH synthesis. We report that the corpora allata in ovariectomised, adult virgins of the German cockroach, Blattella germanica (L.), increase and then decrease in activity, as they do in intact females. Moreover, the distal tubules in the left colleterial glands of ovariectomised females accumulate abundant protein, the production of which is regulated by JH. In both ovariectomised and sham‐operated females, the activity of the corpora allata more than tripled between days 1 and 4 of adulthood, during which the oöcytes of sham‐operated females grew considerably in length. The corpora allata of sham‐operated females produced even more JH on day 7, but very little on day 10, by which time all females had oviposited. The glands of ovariectomised females, by constrast, produced a similar amount of JH on day 7 as on day 4, but much less on day 10. Beginning on day 13, the activity of the corpora allata increased again in ovariectomised females, an increase that did not occur until day 22 in sham‐operated females. Mating of ovariectomised females on day 6 resulted in a significant increase in the activity of the corpora allata by day 10. We conclude that both the ovary and mating stimulate the synthesis of JH early in the reproductive cycle, but that neither is needed for the occurrence of a complete cycle of JH synthesis.
Partial purification of the aminopeptidase from the midgut of the human body louse, Pediculus humanus humanus
Authors: Ochanda James O. , Oduor Eva A. C. , Galun Rachel , Imbuga Mabel O. , Mumcuoglu Kosta Y.
Published: March 2003

The midgut of the human body louse Pediculus humanus humanus contains a thermally stable leucine aminopeptidase, which was detected by agarose gel electrophoresis using
l‐amino oxidase. Midgut extracts were homogenized in saline or in 1% Triton X‐100 and the aminopeptidase was purified by Superose 6 gel filtration chromatography. A peak with enzyme activity that was extracted with or without Triton X‐100 was eluted at a molecular weight 67–69 kDa. Non‐denaturing polyacrylamide gel electrophoresis resolved one band of molecular weight of 69 kDa for samples that were extracted in a saline buffer. Two closely linked bands of molecular weight 67 kDa and 69 kDa were observed in samples that were extracted in 1% Triton X‐100.
Granulovirus prevents pupation and retards development of Adoxophyes honmai larvae
Authors: Nakai Madoka , Goto Chie , Shiotsuki Takahiro , Kunimi Yasuhisa
Published: March 2003

Abstract Larvae of Adoxophyes honmai (Lepidoptera: Tortricidae) infected with granulovirus (AdhoGV) do not pupate; instead, they undergo prolonged larval development and die during the final stadium. Non‐infected larvae, however, pupate after five larval stadia. Insect metamorphosis is regulated by fluctuations of ecdysteroid and Juvenile Hormone (JH). JH esterase activity and titres of ecdysteroid must be measured to understand fully the interaction of an insect virus and its host. JH esterase activity is consistently low in AdhoGV‐infected larvae, which suggests that JH in AdhoGV‐infected larvae is not degraded during the final stadium. The ecdysteroid titre in non‐infected larvae showed a large peak in the final stadium before pupation, whereas that in AdhoGV‐infected larvae increased from day 2 to day 5 in the final stadium, and then remained at a high level until death. Furthermore, an ecdysteroid UDP‐glucosyltransferase (EGT) assay showed that this activity occurs in haemolymph from AdhoGV‐infected larvae, but not in haemolymph of non‐infected larvae. PCR and sequencing analysis revealed that the AdhoGV genome contains an egt gene, which encodes a protein of 445 amino acids, located approximately 1 kbp upstream from the granulin gene. These results suggest that AdhoGV‐infected larvae are prevented from pupating because JHE activity is suppressed and EGT expression inactivates ecdysteroid in the haemolymph.
Influence of phosphate starvation on phosphohydrolases during development of tomato seedlings
Authors: Bosse D. , Köck M.
Published: March 2003

In tomato seedlings (Lycopersicon esculentum Mill. cv. Lukullus), phosphate mobilizing enzymes (acid phosphatase, phytase and ribonuclease) responded to the absence of an exogenous phosphate source with a remarkable increase in their specific activities. The definite beginning of a stress response on the level of enzyme activity was revealed at day 10 after sowing. The increase was tightly controlled by the decline of the free cellular phosphate level. Thus, in phosphate‐deficient roots derived from 14‐d‐old seedlings, the enzyme activities were up to 32‐fold higher than in the control plants. Only 7% of the free cellular phosphate content of control roots was measured in this part of the plants. However, phosphate‐starved plants do not show visible deficiency symptoms at this stage. In addition, we found that phosphohydrolases reached their maximum specific activity early in germination, independent of the exogenous phosphate supply. Furthermore, acid phosphatase and ribonuclease isoforms exhibited different patterns depending on the nutrient supply, as well as on the developmental stage. The results of this work allow us to compare the responses of whole tomato plants following phosphate deprivation with those of a homologous suspension cell culture recently examined.
Interactive effects of low atmospheric CO2 and elevated temperature on growth, photosynthesis and respiration in Phaseolus vulgaris
Authors: Cowling S. A. , Sage R. F.
Published: March 2003

For most of the past 250 000 years, atmospheric CO2 has been 30–50% lower than the current level of 360 μmol CO2 mol–1 air. Although the effects of CO2 on plant performance are well recognized, the effects of low CO2 in combination with abiotic stress remain poorly understood. In this study, a growth chamber experiment using a two‐by‐two factorial design of CO2 (380 μmol mol–1, 200 μmol mol–1) and temperature (25/20 °C day/night, 36/29 °C) was conducted to evaluate the interactive effects of CO2 and temperature variation on growth, tissue chemistry and leaf gas exchange of Phaseolus vulgaris. Relative to plants grown at 380 μmol mol–1 and 25/20 °C, whole plant biomass was 36% less at 380 μmol mol–1× 36/29 °C, and 37% less at 200 μmol mol–1× 25/20 °C. Most significantly, growth at 200 μmol mol–1× 36/29 °C resulted in 77% less biomass relative to plants grown at 380 μmol mol–1× 25/20 °C. The net CO2 assimilation rate of leaves grown in 200 μmol mol–1× 25/20 °C was 40% lower than in leaves from 380 μmol mol–1× 25/20 °C, but similar to leaves in 200 μmol mol–1× 36/29 °C. The leaves produced in low CO2 and high temperature respired at a rate that was double that of leaves from the 380μmol mol–1× 25/20 °C treatment. Despite this, there was little evidence that leaves at low CO2 and high temperature were carbohydrate deficient, because soluble sugars, starch and total non‐structural carbohydrates of leaves from the 200μmol mol–1× 36/29 °C treatment were not significantly different in leaves from the 380μmol mol–1× 25/20 °C treatment. Similarly, there was no significant difference in percentage root carbon, leaf chlorophyll and leaf/root nitrogen between the low CO2× high temperature treatment and ambient CO2 controls. Decreased plant growth was correlated with neither leaf gas exchange nor tissue chemistry. Rather, leaf and root growth were the most affected responses, declining in equivalent proportions as total biomass production. Because of this close association, the mechanisms controlling leaf and root growth appear to have the greatest control over the response to heat stress and CO2 reduction in P. vulgaris.
The effects of elevated atmospheric CO2 on lipid metabolism in leaves from mature wheat (Triticum aestivum cv. Hereward) plants
Authors: Williams M. , Robertson E. J. , Leech R. M. , Harwood J. L.
Published: March 2003

Winter wheat (Triticum aestivum L. cv. Hereward) plants were grown for 35 d either at 350 μmol mol–1 CO2 or at 650 μmol mol–1 CO2. Lipid synthesis was studied in these plants by incubating the 5th leaf on the main stem with [1–14C]acetate. Increased CO2 concentrations did not significantly affect the total incorporation of radiolabel into lipids of whole leaf tissue, but altered the distribution for individual lipid classes. Most noticeable amongst acyl lipids was the reduction in labelling of diacylglycerol and a corresponding increase in the proportion of phosphatidylcholine labelling. In the basal regions, there were similar changes and, in addition, phosphatidylglycerol labelling was particularly increased following growth in an enriched CO2 atmosphere. The stimulation of labelling of the mitochondrial‐specific lipid, diphosphatidylglycerol, prompted an examination of the mitochondrial population in wheat plants. Mitochondria were localized in intact wheat sections by immunolabelling for the mitochondrial‐specific chaperonin probe. Growth in elevated CO2 doubled the number of mitochondria compared to growth in ambient CO2. Fatty acid labelling was also significantly influenced following growth at elevated CO2 concentrations. Most noticeable were the changes in 16C:18C ratios for the membrane lipids, phosphatidylcholine, phosphatidylglycerol and monogalactosyldiacylglycerol. These data imply a change in the apportioning of newly synthesized fatty acids between the ‘eukaryotic’ and ‘prokaryotic’ pathways of metabolism under elevated CO2.
Inhibition of photosynthesis and export in geranium grown at two CO2 levels and infected with Xanthomonas campestris pv. Pelargonii
Authors: JIAO J. , GOODWIN P. , GRODZINSKI B.
Published: March 2003

The effects of CO2 enrichment on growth of Xanthomonas campestris pv. pelargonii and the impact of infection on the photosynthesis and export of attached, intact, ‘source’ leaves of geranium (Pelargonium x domesticum, ‘Scarlet Orbit Improved’) are reported. Two experiments were performed, one with plants without flower buds, and another with plants which were flowering. Measurements were made on healthy and diseased leaves at the CO2 levels (35 Pa or 90 Pa) at which the plants were grown. There were no losses of chlorophyll, or any signs of visible chlorosis or necrosis due to infection. Lower numbers of bacteria were found in leaves at high CO2, suggesting growth at elevated CO2 created a less favourable condition in the leaf for bacterial growth. Although high CO2 lowered the bacterial number in infected leaves, reductions in photosynthesis and export were greater than at ambient CO2. The capacity of infected source leaves to export photoassimilates at rates observed in the controls was reduced in both light and darkness. In summary, the severity of infection on source leaf function by the bacteria was increased, rather than reduced by CO2 enrichment, underscoring the need for further assessment of plant diseases and bacterial virulence in plants growing under varying CO2 levels.
The interaction between elevated carbon dioxide and nitrogen nutrition: the physiological and molecular background
Authors: STITT M. , KRAPP A.
Published: March 2003

AGPase, ADP glucose pyrophosphorylase GS, glutamine synthetase GOGAT, glutamate : oxoglutarate amino transferase NADP‐ICDH, NADP‐dependent isocitrate dehydrogenase NR, nitrate reductase OPPP, oxidative pentose phosphate pathway 3PGA, glycerate‐3‐phosphate PEPCase, phosphoenolpyruvate carboxylase Rubisco, ribulose‐1,5‐bisphosphate carboxylase/oxygenase SPS, sucrose phosphate‐synthase  This review first summarizes the numerous studies that have described the interaction between the nitrogen supply and the response of photosynthesis, metabolism and growth to elevated [CO2]. The initial stimulation of photosynthesis in elevated [CO2] is often followed by a decline of photosynthesis, that is typically accompanied by a decrease of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco), an accumulation of carbohydrate especially starch, and a decrease of the nitrogen concentration in the plant. These changes are particularly marked when the nitrogen supply is low, whereas when the nitrogen supply is adequate there is no acclimation of photosynthesis, no major decrease in the internal concentration of nitrogen or the levels of nitrogen metabolites, and growth is stimulated markedly. Second, emerging evidence is discussed that signals derived from nitrate and nitrogen metabolites such as glutamine act to regulate the expression of genes involved in nitrate and ammonium uptake and assimilation, organic acid synthesis and starch accumulation, to modulate the sugar‐mediated repression of the expression of genes involved in photosynthesis, and to modulate whole plant events including shoot–root allocation, root architecture and flowering. Third, increased rates of growth in elevated [CO2] will require higher rates of inorganic nitrogen uptake and assimilation. Recent evidence is discussed that an increased supply of sugars can increase the rates of nitrate and ammonium uptake and assimilation, the synthesis of organic acid acceptors, and the synthesis of amino acids. Fourth, interpretation of experiments in elevated [CO2] requires that the nitrogen status of the plants is monitored. The suitability of different criteria to assess the plant nitrogen status is critically discussed. Finally the review returns to experiments with elevated [CO2] and discusses the following topics: is, and if so how, are nitrate and ammonium uptake and metabolism stimulated in elevated [CO2], and does the result depend on the nitrogen supply? Is acclimation of photosynthesis the result of sugar‐mediated repression of gene expression, end‐product feedback of photosynthesis, nitrogen‐induced senescence, or ontogenetic drift? Is the accumulation of starch a passive response to increased carbohydrate formation, or is it triggered by changes in the nutrient status? How do changes in sugar production and inorganic nitrogen assimilation interact in different conditions and at different stages of the life history to determine the response of whole plant growth and allocation to elevated [CO2]?
Effects of air pollutants on proton and sucrose transport at the plasma membrane of Ricinus communis
Authors: RUSSELL C. E. , PITTMAN J. , DARRALL N. M. , WILLIAMS L. E. , HALL J. L.
Published: March 2003

The effects of the air pollutants O3, SO2 and NO2 on aspects of sucrose/proton cotransport across the plasma membrane of Ricinus communis plants have been investigated. The H+‐ATPase hydrolytic activity in cotyledon plasma membrane vesicles purified by phase partitioning showed small stimulations by Na2SO3 or NaNO3 added separately or together to the assay medium. ATPase activity from plants pretreated by fumigation with SO2 or O3 also showed an increase, the effect of O3 being quite marked. Plasma membrane H+‐pumping in KI‐treated microsomal fractions and medium acidification by intact cotyledons both showed small decreases in the presence of Na2SO3 or NaNO2. Both Na2SO3 and NaNO2 at high concentrations (2 mol m–3) had significant effects on sucrose uptake by intact cotyledons, although sucrose efflux was unaffected. No significant effects on sucrose uptake or efflux by intact cotyledons were observed in plants pretreated by fumigation with SO2 or O3. Proton‐coupled sucrose transport in isolated plasma membrane vesicles was inhibited in the presence of Na2SO3 or NaNO2. However, both pollutants also significantly inhibited the uptake of acetate by the vesicles, indicating a dissipation of the pH gradient across the membrane. It was concluded that no specific aspect of the sucrose/proton cotransport mechanism was damaged by these air pollutants, and that the effects of these pollutants on carbohydrate partitioning are more likely to be due to general effects on membrane integrity or on other aspects such as leaf carbohydrate metabolism.
Differential response of four tree species to ozone‐induced acceleration of foliar senescence
Authors: Pell E. J. , Sinn J. P. , Brendley B. W. , Samuelson L. , Vinten‐Johansen C. , Tien M. , Skillman J.
Published: March 2003

Ozone (O3)‐induced accelerated senescence of leaves was measured in four tree species: black cherry (Prunus serotina), hybrid poplar (Populus maximowizii x trichocarpa, clone 245), northern red oak (Quercus rubra) and sugar maple (Acer saccharum). Seedlings or ramets of the four species were subjected to chronic O3 exposures and designated leaves harvested periodically from emergence to senescence. Gas exchange was analysed, and concentrations of total soluble protein and ribulose‐1,5‐bisphosphate carboxylase/oxygenase were measured as indicators of leaf senescence. Total antioxidant potential and ascorbate peroxidase and glutathione reductase activities also were determined. Black cherry and hybrid poplar exhibited O3‐induced accelerated leaf senescence, whereas sugar maple and northern red oak did not. When the O3 effects were related to cumulative uptake of the gas, black cherry was the most sensitive of the four species. Although hybrid poplar exhibited similar symptoms of O3‐induced accelerated senescence after the same exposure period as did black cherry, this species took up much greater quantities of O3 to achieve the same response. The O3‐induced increase in glutathione reductase activity in hybrid poplar was consistent with the capacity of this species to take up high concentrations of the gas. Relative tolerance of northern red oak and sugar maple could be explained only in part by lower cumulative O3 uptake and lower rate of uptake. Sugar maple had the highest antioxidant potential of all four species, which may have contributed to O3 tolerance of this species. Ascorbate peroxidase activity, when expressed on a fresh weight basis, could not account for differential sensitivity among the four species.
CO2 is the main inorganic C species entering photosynthetically active leaf protoplasts of the freshwater macrophyte Ranunculus penicillatus ssp. pseudofluitans
Authors: Newman J. R. , Raven J. A.
Published: March 2003

Submerged aquatic macrophytes growing in water where free CO2 is unavailable (above pH 8·2) must use mechanisms to supply external dissolved inorganic carbon in a form available to chloroplasts (CO2). Active transport of HCO3– across the plasmalemma has not been proven to be widespread in aquatic macrophytes and catalytic conversion of HCO3– to CO2 is the usual supply mechanism in submerged macrophytes. The interaction of leaf form and function in this respect was investigated in the linear, submerged leaves of Ranunculus penicillatus (Dumort.) Bab ssp. pseudofluitans (Syme) S.Webster. Viable protoplasts were isolated using a mixture of cell wall degrading enzymes optimized for this species. Protoplast viabilities greater than 80% after 5 h of isolation were achieved. Photosynthetic rates of isolated protoplasts were comparable with that of intact plant tissue. Results of carbon isotopic disequilibrium experiments showed that CO2 was the preferred species of dissolved inorganic carbon for photosynthesis by protoplasts and that HCO3– which predominates in the plant’s natural environment mainly contributes by supplying CO2 outside the cells.
Sodium/potassium selectivity and pleiotropy in stl2, a highly salt‐tolerant mutation of Ceratopteris richardii
Authors: Warne T. R. , Hickok L. G. , Sams C. E. , Vogelien D. L.
Published: March 2003

The roles of Na+ and K+ (Rb+) uptake were further studied in a NaCl‐tolerant strain of Ceratopteris richardii containing the stl2 mutation by direct comparison with the wild‐type strain. In addition to Na+ tolerance, stl2 also confers tolerance to Mg2+ and sensitivity to K+. In addition to higher K+ (Rb+) uptake at concentrations commonly associated with low‐affinity K+ transport, stl2 maintained higher uptake down to 0·1 mol m–3 Rb+. Up to a 25‐fold excess of Na+ had little effect in either genotype on K+ (Rb+) uptake at low concentrations, i.e. 0·2 and 0·5 mol m–3 RbCl. Pretreatment with K+ (20 mol m–3) inhibited uptake of K+ (Rb+) in the wild type, whereas concurrent inclusion of K+ inhibited uptake of Rb+ more in stl2. In the absence of K+, Na+ uptake (0·01–60 mol m–3) was nearly identical in the wild type and stl2. K+ inhibited Na+ uptake more effectively in stl2 than the wild type, especially at 60 mol m–3 Na+. Greater inhibition of K+ uptake in stl2 occurred with MgCl2 or TEA (tetraethylammonium chloride) preincubation or with simultaneous inclusion of Al3+ (Al2SO4). The higher effective velocity of K+ uptake at a wide range of concentrations and the enhanced selectivity for K+ and against Na+ contribute to the preservation of higher cytosolic K+ and lower Na+ under salinity stress.
Imbibitional leakage from anhydrobiotes revisited
Authors: Hoekstra F. A. , Golovina E. A. , Aelst A. C. Van , Hemminga M. A.
Published: March 2003

Dry desiccation‐tolerant organ(ism)s leak cellular solutes when placed in water. Elevated temperatures at imbibition and elevated initial moisture contents reduce the leakage and promote growth. We have re‐examined the effects of imbibitional stress imposed on cattail (Typha latifolia L.) pollen as a model anhydrobiotic system. A nitroxide spin probe technique and electron microscopy were used, allowing study of the permeability of the plasma membrane together with its visual intactness. Imbibitional leakage can be transient, or prolonged when associated with membrane damage. During the first 15 s of rehydration in medium, plasma membranes of pre‐humidified pollen were highly permeable but became less permeable thereafter. The resulting transient leakage may affect vigour as measured by the rate of fresh weight increase, but did not reduce germination. A permanent, high permeability was observed when dry pollen was plunged into medium at low temperatures. This led to cell death and is associated with a phase change of the membranes from gel to liquid crystalline during imbibition. Freeze‐fracture images indicate that the damage to plasma membranes is mechanically imposed by the pressure of the penetrating water rather than occurring structurally by a phase separation of membrane components. We suggest that a high rigidity of the plasma membranes in the gel phase at imbibition underlies imbibitional damage.