bluuebunny/crossref_metadata_2025 huggingface dataset:
Farber's disease diagnosed by nerve biopsy
Authors: Jacobs J. , Groves M. , Martinez A. , Harding B.
Published: March 2003

Introduction:  Farber's disease (granulomatosis) is a rare inherited lipid storage disease caused by a deficiency of lysosomal acid‐ceramidase. Clinical features include contractures of limbs with swelling of joints and multiple subcutaneous nodules. In a few cases there is prominent involvement of central and peripheral nervous systems. Ceramide accumulates in the nodules and in cells of many other tissues including brain. Electron microscopy of affected cells shows membrane‐bound inclusions, some of which have a highly characteristic curved or ‘banana’ shape (Farber bodies). Nerve biopsy findings have been described in a few cases but our patient appears to be the first to have been diagnosed by nerve biopsy.

Case report:  This male infant presented at 6 months with joint pain and swelling, fever weakness and nystagmus: EMNG demonstrated sensory‐motor polyneuropathy with features of demyelination. Semi‐thin resin sections show a moderately reduced density of myelinated fibres. The myelin sheaths of most fibres are inappropriately thin, which was confirmed morphometrically: some axons are demyelinated. Vacuolar inclusions are seen in some Schwann cells. Teased fibres show de‐ and remyelination. Electron microscopy shows oval, boomerang‐ or banana‐shaped inclusions in Schwann cells associated with myelinated and unmyelinated axons, but not in other cell types.

Conclusion:  Farber's disease is associated with a demyelinating neuropathy.
Carob bean juice: a powerful adjunct to oral rehydration solution treatment in diarrhoea
Authors: Akşit Sadik , Çagˇlayan Suat , Cukan Ramazan , Yaprak Işin
Published: March 2003

In children, the treatment of acute diarrhoea with the World Health Organization (WHO) standard oral rehydration solution (ORS) provides effective rehydration but does not reduce the severity of diarrhoea. In community practice, carob bean has been used to treat diarrhoeal diseases in Anatolia since ancient times. In order to test clinical antidiarrhoeal effects of carob bean juice (CBJ), 80 children, aged 4–48 months, who were admitted to SSK Tepecik Teaching Hospital with acute diarrhoea and mild or moderate dehydration, were randomly assigned to receive treatment with either standard WHO ORS alone or a combination of standard WHO ORS and CBJ. Three patients were excluded from the study because of excessive vomiting. In the children receiving ORS + CBJ the duration of diarrhoea was shortened by 45%, stool output was reduced by 44% and ORS requirement was decreased by 38% compared with children receiving ORS alone. Weight gain was similar in the two groups at 24 Êh after the initiation of the study. Hypernatraemia was detected in three patients in the ORS group but in none of those in the ORS + CBJ group. The use of CBJ in combination with ORS did not lead to any clinical metabolic problem. We therefore conclude that CBJ may have a role in the treatment of children's diarrhoea after it has been technologically processed, and that further studies would be justified.
Lower respiratory tract infections in an ethnic and social context
Authors: Hjern Anders , Haglund Bengt , Bremberg Sven
Published: March 2003

Family size and smoking during pregnancy were studied as mediating factors for social and ethnic variation of lower respiratory tract infection (LRI) in hospital discharge data. The study population consisted of all children aged 0–4 years in the three largest metropolitan areas of Sweden during 1990–94. Maternal smoking during pregnancy increased the risk of children being admitted to hospital for LRI during their first 3 years of life, with an adjusted odds ratio (OR) of 1.3 for the age‐group 0–1 years. The risk attributed to smoking during pregnancy was the same in children of mothers in ethnic groups in which smoking during pregnancy was related to social adversity as in those in which it was not. Having at least one sibling increased the risk of being admitted to hospital for LRI in the age group 0–1 years (adjusted OR 2.2). This risk was lower in children in families in which the mother was born in southern Europe, Africa, Asia or Latin America, suggesting a contextual relation to ethnicity for this risk factor. It is concluded that family size and smoking during pregnancy are important mediators of the risk for LRI related to social adversity and ethnicity in Swedish children below 2 years of age.
Maternal experiences of racism and violence as predictors of preterm birth: rationale and study design
Authors: Rich‐Edwards Janet , Krieger Nancy , Majzoub Joseph , Zierler Sally , Lieberman Ellice , Gillman Matthew
Published: March 2003

Chronic psychological stress may raise the risk of preterm delivery by raising levels of placental corticotropin‐releasing hormone (CRH). Women who have been the targets of racism or personal violence may be at particularly high risk of preterm delivery. The aims of this study are to examine the extent to which: (1) maternal experiences of racism or violence in childhood, adulthood, or pregnancy are associated with the risk of preterm birth; (2) CRH levels are prospectively associated with risk of preterm birth; and (3) CRH levels are associated with past and current maternal experiences of racism or violence. We have begun to examine these questions among women enrolled in Project Viva, a Boston‐based longitudinal study of 6000 pregnant women and their children.
Trends and characteristics of induced labour in the United States, 1989–98
Authors: MacDorman Marian F. , Mathews T. J. , Martin Joyce A. , Malloy Michael H.
Published: March 2003

Induction of labour is one of the fastest growing medical procedures in the United States. In 1998, 19.2% of all US births were a product of induced labour, more than twice the 9.0% in 1989. Induction of labour has been efficacious in the management of post‐term pregnancy and in expediting delivery when the mother or infant is sufficiently ill to make continuation of the pregnancy hazardous. However, the recent rapid increase in induction, and particularly the doubling of the induction rate for preterm pregnancies (from 6.7% in 1989 to 13.4% in 1998), has generated concern among some clinicians. The present study uses vital statistics natality data to examine the epidemiology of induced labour in the US. Multivariable analysis is used to examine the probability of having an induced delivery in relation to a wide variety of socio‐demographic and medical characteristics, and also in relation to relative indications and contraindications for induced labour as outlined by the American College of Obstetricians and Gynecologists (ACOG).

Induction rates were higher for women who were non‐Hispanic white, college educated, born in the US, primaparae and those with intensive prenatal care utilisation. Induction rates were also higher for women with various medical conditions including hypertension, eclampsia and renal disease. For non‐Hispanic white women with singleton births, 59% of the increase in the preterm birth rate from 1989 to 1998 can be accounted for by the increase in preterm inductions. The adjusted odds ratio for neonatal mortality among preterm births with induced labour was 1.20 [95% confidence interval 1.11, 1.31]. The rapid increase in induction rates, particularly among preterm births, marks a shift in the obstetric management of pregnancy. More detailed studies are needed to examine physician decision‐making protocols, particularly for preterm induction, and to assess the impact of these practice changes on patient outcomes.
Intranasal immunization with yeast‐expressed 19 kD carboxyl‐terminal fragment of Plasmodium yoelii merozoite surface protein‐1 (yMSP119) induces protective immunity to blood stage malaria infection in mice
Authors: HIRUNPETCHARAT CHAKRIT , STANISIC DANIELLE , LIU XUE QIN , VADOLAS JIM , STRUGNELL RICHARD A. , LEE ROGAN , MILLER LOUIS H. , KASLOW DAVID C. , GOOD MICHAEL F.
Published: March 2003

Variable protection against malaria blood‐stage infection has been demonstrated in mice following parenteral immunization with the highly conserved 19 kD carboxylterminal fragment of the merozoite surface protein‐1 (MSP119) using CFA/IFA and other adjuvants. Here we show that intranasal immunization of BALB/C mice with yeast expressed Plasmodium yoelii MSP119 plus a mixture of native and recombinant cholera toxin B subunit, could induce serum MSP119‐specific antibodies at titres ranging from 20 000 to 2 560 000. The Ig subclass responses were predominantly G1 and G2b. Intranasal immunization led to protection following challenge (peak parasitaemia < 1%) in mice with the highest MSP119‐specific titre (≥ 640 000). In two of the three protected mice, a peak parasitaemia of 0.1%–1% was followed by a boost of the antibody response whereas one of the three protected mice did not boost its antibody response after a peak parasitaemia of 0.02%. In unprotected mice, antibody levels rose, then fell, following the detection of parasites in the peripheral blood. CD4+ T cell‐depletion abrogated the ability of the mice to boost their antibody response following challenge. These data demonstrate the potential for intranasal immunization with MSP119 to protect against malaria.
Characterization of murine Th1 clones specific to egg antigen of Schistosoma japonicum and their interaction with cytokines
Authors: Yang Jun‐Qi , Tasaka Kachio , Chuang Cheng‐Kuo , Yoshikawa Hideshi , Nakajima Yasuo
Published: March 2003

T cell clones (B1, B21, B7, A25) specific to the soluble egg antigen (SEA) of Schistosoma japonicum were established from C3H/He mice immunized with SEA. These clones belonged to CD3+ , CD4+ and CD8−Th1 cells, showing TCR‐γδ−, TCR‐αβ+ and Vβ10b+. The molecular weights of target antigens recognized by the clones ranged from 51 to 80 kDa. Interleukin‐2 (IL‐2) and IL‐12 could vigorously increase the proliferation response of the T clones to SEA; while IL‐10 and transforming growth factor‐β1 (TGF‐β1) strongly inhibited the response. IL‐12 activity was detected in the culture supernatant of T clones stimulated with SEA in the presence of APC (antigen presenting cells). This stimulation also upregulated the expression of the IL‐12 receptor on the T clones. IL‐12 from APC served as a costimulatory factor for the SEA induced proliferation of the T clone cells. Clone B1 was able to induce granuloma formation both in vivo and in vitro. These data provide further insight into the complicated interaction among SEA, T cell and cytokine at a clonal level in S. japonicum infection.
A glycoprotein from Schistosoma mansoni eggs binds non‐antigen‐specific immunoglobulin E and releases interleukin‐4 from human basophils
Authors: Haisch Karin , Schramm Gabriele , Falcone Franco H. , Alexander Christian , Schlaak Max , Haas Helmut
Published: March 2003

We have recently shown that soluble extracts from Schistosoma mansoni eggs (SmEA) triggered basophils from nonsensitized donors to rapidly release interleukin (IL)‐4. Assuming that this mechanism might play a role in vivo in biasing the immune response towards a Th2 phenotype, we determined basic properties of the IL‐4‐inducing activity contained in SmEA. Sensitivity to pepsin digestion indicated protein nature. Binding to and specific elution from Concanavalin A‐sepharose suggested that this protein contains mannose residues, thus being a glycoprotein. The IL‐4‐inducing activity was stable for 30 min at room temperature towards shifting the pH between 3 and 10. When incubated at 100°C, it was stable at pH 3, but less stable at neutral and alkaline pH. Electroelution from an SDS‐PAGE gel indicated an apparent molecular weight of the IL‐4‐inducing activity between 31 and 66 kDa. Although binding to purified human immunoglobulin E (IgE) and activating basophils IgE‐dependently, SmEA appears to activate basophils in a non‐antigen‐specific way, since the cells were purified from noninfected donors. Because the IL‐4‐inducing activity was found to be released from eggs, it could be an important factor in the environment of the eggs skewing the immune response towards the Th2 phenotype.
Nitric oxide and reactive nitrogen intermediates during lethal and nonlethal strains of murine malaria
Authors: Nahrevanian Hossein , Dascombe Michael J.
Published: March 2003

The virulence of Plasmodia depends partly on the strain of parasite and partly on the host. In this study, Plasmodium berghei N/13/1A/4/203 caused the death of mice, whereas Plasmodium chabaudi chabaudi AS was not lethal. Current opinion is that nitric oxide (NO) and other reactive nitrogen intermediates (RNI) are produced in several host organs during malaria to resist infection or produce tissue damage. NO and RNI production in blood or plasma, brain, liver and spleen in MF1 mice was investigated during P. berghei and P. c. chabaudi infection, in order to help determine whether changes in NO production are beneficial or detrimental to the host in vivo. NO production was measured both directly and indirectly as nitrites and nitrates, to represent RNI. No changes in blood NO were detected in P. berghei infected mice, but increases were observed in brain, liver and spleen. In P. c. chabaudi infected mice, rises in NO concentration were observed in blood and spleen, whereas a decline in liver NO was seen, but there were no changes in brain. Liver contained the highest concentration of RNI, but increasing concentrations were seen in both plasma and spleen in both P. berghei and P. c. chabaudi infected mice. These results show that NO and RNI production alters during murine malaria. The changes depend upon the tissue, the day of infection, the degree of parasitaemia, the strain of Plasmodia and the method of measuring NO biosynthesis. Lethal P. berghei induced NO production in the mid and late stages of infection in mice when parasitaemia was high, whereas in nonlethal P. c. chabaudi infection, NO production was increased in the early and late stages when parasitaemia was low. These data are consistent with a role for NO in the protection of the MF1 mouse against Plasmodia. Failure to clear the parasite is associated with evidence of increased NO production in brain and liver, which may contribute to the pathology of malaria, but this hypothesis requires confirmation from other experimental approaches.
Effect of oxygen radicals and differential expression of catalase and superoxide dismutase in adult Heligmosomoides polygyrus during primary infections in mice with differing response phenotypes
Authors: Ben‐Smith A. , Lammas D. A. , Behnke J. M.
Published: March 2003

The ability of oxygen radicals to kill Heligmosomoides polygyrus adult worms was examined by assessing parasite survival following incubation with hydrogen peroxide and acetaldehyde/xanthine oxidase, generators ofH2O2and H2O2/O2–, respectively. H. polygyrus worms could tolerate levels of < 0·25 mMhydrogen peroxide and < 0·5 mM/20 mU acetaldehyde/xanthine oxidase for 20 h, but, at higher concentrations, marked sex‐dependent susceptibility was observed, with males being more sensitive toH2O2and O2–than female worms. The ability to evade free radical‐mediated damage was also evaluated by measuring superoxide dismutase (SOD) and catalase levels in worms isolated at different time points from four strains of mice with differing resistance phenotypes. Levels of both catalase and SOD in female worms isolated from ‘rapid’[(SWRxSJL)F1], ‘fast’ (SWR) or ‘intermediate’ (BALB/c), but not ‘slow’ (C57BL/10), responder mice showed a strain‐dependent increase with time. Moreover, male worms were rejected faster than female worms in the ‘rapid’, ‘fast’ and ‘intermediate’ responder strains of mice. The results suggest that host‐derived free radicals can damage adult worms and that female worms can increase production of their scavenging enzymes in response to the immune onslaught that eventually leads to worm expulsion in mice with ‘fast’, ‘rapid’ or ‘intermediate’ response phenotypes.
EAG and behavioural responses of the larger grain borer, Prostephanus truncatus, and its predator, Teretriosoma nigrescens, to the borer‐produced aggregation pheromone
Authors: SCHOLZ D. , BORGEMEISTER C. , POEHLING H. ‐M.
Published: March 2003

Abstract.Electroantennogram (EAG) and behavioural studies were conducted with Prostephanus truncatus (Horn) (Col.: Bostrichidae) and the predatory beetle, Teretriosoma nigrescens Lewis (Col: Histeridae) in regard to their responses to the components of the prey‐produced aggregation pheromone. There were hardly any differences between species or sexes regarding perception thresholds. In field and olfactometer experiments, female P. truncatus were more responsive to the pheromone than males, and both sexes reacted more strongly to the minor pheromone component, T2, than to T1. Sex ratios among trap catches of T. nigrescens were slightly male‐biased. The predator did not differentiate behaviourally between the pheromone components.
Phytosterol structure and its impact on feeding behaviour in the generalist grasshopperSchistocerca americana
Authors: Behmer Spencer T. , Elias Damian O.
Published: March 2003

Abstract.Sixth‐stadium nymphs of the grasshopper Schistocerca americana (Drury) (Orthoptera: Acrididae) were observed in a series of experiments designed to measure feeding behaviour in response to suitable and unsuitable phytosterols. In the first experiment, grasshoppers were presented with artificial diet that contained either sitosterol, a suitable phytosterol, or a spinach lipid extract which contained only unsuitable sterols as well as other spinach lipids. The diet with the spinach lipid extract, but not the sitosterol diet, evoked a deterrent response. To determine if the spinach sterols were responsible for the deterrent response, a second experiment was performed where the spinach lipid extract was separated into three lipid classes, including desmethyl sterols, dimethyl sterols and the remaining spinach lipids. Grasshoppers presented with artificial diet containing the desmethyl sterols (the end‐product sterols in spinach) exhibited deterrent responses. Finally, feeding behaviour to a suite of different sterols, including cholesterol (suitable), stigmasterol (unsuitable), and lathosterol (unsuitable), was observed; these sterols were selected because they show variation in the position of double bonds. Grasshoppers presented with diets containing unsuitable sterols again exhibited deterrent responses. Overall, the deterrent effect was strongest when sterols with a double bond at position 22 were in the diet.
Quantifying the symbiont contribution to essential amino acids in aphids: the importance of tryptophan for Uroleucon ambrosiae
Authors: Bernays E. A. , Klein B. A.
Published: March 2003

A complete amino acid budget was constructed using the aphid Uroleucon ambrosiae (Strecker), feeding on a suboptimal host, Tithonia fruticosa. The availability of amino acids was estimated from phloem analyses and phloem intake rates at each stage of development. Requirements for amino acids were estimated from gravimetric studies and from analyses of body amino acids. Because the budget was found to be well balanced, estimates of specific needs and shortfalls of essential amino acids were calculated, thus quantifying the role of symbiotic bacteria in fulfilling needs for these amino acids. The most dramatic shortfall was for tryptophan, consistent with the amplification of relevant genes in the symbiont.
Measuring and modelling environmental influences on photosynthetic gas exchange in Sphagnum and Pleurozium
Authors: Williams T. G. , Flanagan L. B.
Published: March 2003

A mechanistic model has been used to examine the environmental regulation of photosynthetic gas exchange in moss. The effects of water content on conductance to CO2 and on photosynthetic capacity during desiccation were calculated from the carbon isotope discrimination data of Williams & Flanagan (1996, Oecologia 108, pp. 38–46) and combined with the biochemical model of Farquhar et al. (1980, Planta 149, pp. 78–90). The model includes a simple light attenuation function that imparts curvature to the light response curve for net assimilation, enabling the use of physiologically realistic values for the biochemical parameters. Measurements of gas exchange for Sphagnum and Pleurozium were made in an old black spruce ecosystem over a growing season in order to assign values to parameters in the model. The calculated maximum rates of carboxylation by Rubisco (Vmax) were 5, 14 and 6μmol m–2 s–1 for Sphagnum during the spring, summer and autumn seasons of 1996, respectively. The increase in Vmax during the summer was consistent with an increased allocation of resources to the photosynthetic apparatus. In contrast, no seasonal variation in Vmax was observed in Pleurozium with average values of 7, 5 and 7 μmol m–2 s–1 during the spring, summer and autumn, respectively.
Effect of phosphorus supply on the formation and function of proteoid roots of white lupin (Lupinus albus L.)
Authors: Keerthisinghe G. , Hocking P. J. , Ryan P. R. , Delhaize E.
Published: March 2003

We investigated (1) the effect of constant and altered inorganic phosphate (Pi) supply (1–100 mmol m–3) on proteoid root production by white lupin (Lupinus albus L.); and (2) the variation in citrate efflux, enzyme activity and phosphate uptake along the proteoid root axis in solution culture. Proteoid root formation was greatest at Pi solution concentrations of 1–10 mmol m–3 and was suppressed at 25 mmol m–3 Pi and higher. Except at 1 mmol m–3 Pi, the formation of proteoid roots did not affect plant dry matter yields or shoot to root dry matter ratios, indicating that proteoid roots can form under conditions of adequate P supply and not at the expense of dry matter production. Plants with over 50% of the root system as proteoid roots had tissue P concentrations considered adequate for maximum growth, providing additional evidence that proteoid roots can form on P‐sufficient plants. There was an inverse relationship between the Pi concentration in the youngest mature leaf and proteoid root formation. Citrate efflux and the activities of enzymes associated with citric acid synthesis (phosphoenolpyruvate carboxylase and malate dehydrogenase) varied along the proteoid root axis, being greatest in young proteoid rootlets of the 1–3 cm region from the root tip. Citrate release from the 0–1 and 5–9 cm regions of the proteoid root was only 7% (per unit root length) of that from the 1–3 cm segment. Electrical potential and 32Pi uptake measurements showed that Pi uptake was more uniform along the proteoid root than citrate efflux.
Acclimation of photosynthesis, H2O2 content and antioxidants in maize (Zea mays) grown at sub‐optimal temperatures
Authors: Kingston‐Smith A. H. , Harbinson J. , Foyer C. H.
Published: March 2003

Maize plants were grown at 14, 18 and 20 °C until the fourth leaf had emerged. Leaves from plants grown at 14 and 18 °C had less chlorophyll than those grown at 20 °C. Maximal extractable ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) activity was decreased at 14 °C compared with 20 °C, but the activation state was highest at 14 °C. Growth at 14 °C increased the abundance (but not the number) of Rubisco breakdown products. Phosphoenolpyruvate carboxylase (PEPC) activity was decreased at 14 °C compared with 20 °C but no chilling‐dependent effects on the abundance of the PEPC protein were observed. Maximal extractable NADP‐malate dehydrogenase activity increased at 14 °C compared with 20 °C whereas the glutathione pool was similar in leaves from plants grown at both temperatures. Foliar ascorbate and hydrogen peroxide were increased at 14 °C compared with 20 °C. The foliar hydrogen peroxide content was independent of irradiance at both growth temperatures. Plants grown at 14 °C had decreased rates of CO2 fixation together with decreased quantum efficiencies of photosystem (PS) II in the light, although there was no photo‐inhibition. Growth at 14 °C decreased the abundance of the D1 protein of PSII and the PSI psaB gene product but the psaA gene product was largely unaffected by growth at low temperatures. The relationships between the photosystems and the co‐ordinate regulation of electron transport and CO2 assimilation were maintained in plants grown at 14 °C.
New approach of monitoring changes in chlorophyll a fluorescence of single guard cells and protoplasts in response to physiological stimuli
Authors: Goh C.‐H. , Schreiber U. , Hedrich R.
Published: March 2003

A new type of microfluorometer was applied to assess photosynthesis at the single‐cell level by chlorophyll fluorescence using the saturation pulse method. A microscopy–pulse amplitude modulation (PAM) chlorophyll fluorometer was combined with a Zeiss Axiovert 25 inverted epifluorescence microscope for high‐resolution measurements on single mesophyll and guard cells and the respective protoplasts. Available information includes effective quantum yield of photosystem II, relative electron transport rate and energization of the thylakoid membrane due to the transthylakoidal proton gradient. Dark–light induction curves of guard cell (GCPs) and mesophyll cell protoplasts (MCPs) displayed very similar characteristics, indicating similar functional organization of thylakoid membranes in both types of chloroplasts. Light response curves, however, revealed much earlier saturation of photosynthetic electron flow in GCPs than in MCPs. Under anaerobiosis, photosynthetic electron flow and membrane energization were severely suppressed. A similar effect was observed in guard cells when epidermal peels were incubated with the fungal toxin fusicoccin which activates the plasma membrane H+‐ATPase and causes irreversible opening of stomata. The drop in electron transport rate was prevented by blocking ATP consumption of the H+ pump or by glucose addition. These results show that chlorophyll fluorescence quenching analysis allows profound insights into stomatal physiology.
Blue‐light requirement for the biosynthesis of an NO2− transport system in the Chlamydomonas reinhardtii nitrate transport mutant S10*
Authors: Quiñones Miguel A. , Galván Aurora , Fernández Emilio , Aparicio Pedro J.
Published: March 2003

The blue‐light requirement for the biosynthesis of nitrite reductase and an NO2– transport system was studied in Chlamydomonas reinhardtii mutant S10. The only oxidized nitrogen species that could be taken up by this mutant was NO2–, due to the presence of NO2– transport systems and the absence of high‐affinity NO3– transporters. NH4+‐grown cells required illumination with blue light to recover the ability to take up NO2– when resuspended in an NO2–‐containing NH4+‐deprived medium. This blue‐light‐ dependent recovery, which took 1 h, could be suppressed by cycloheximide, indicating that protein biosynthesis was involved. The biosynthesis of nitrite reductase took place in cell suspensions irradiated with red light, even in the absence of NO2–, thus suggesting that the process requiring blue light was the biosynthesis of an NO2– transport system. Nitrite reductase‐containing cells (pre‐irradiated with red light) took 1 h to start consuming NO2– when they were additionally irradiated with blue light in the presence of this anion, and this process was also cycloheximide‐sensitive. The NO2– transport system operated either under red plus blue light or red light only. Thus, in C. reinhardtii mutant S10 cells, blue light was only required for the biosynthesis of an NO2– transport system and not for its activity.
Phosphate uptake in Arabidopsis thaliana: dependence of uptake on the expression of transporter genes and internal phosphate concentrations
Authors: Dong B. , Ryan P. R. , Rengel Z. , Delhaize E.
Published: March 2003

Changes in the expression of phosphate transporter genes APT1 and APT2, phosphate uptake and internal phosphate concentrations were monitored in Arabidopsis thaliana plants grown with different supplies of inorganic phosphate. When plants were deprived of phosphate, APT1/APT2 expression and phosphate uptake, measured by both 32P and phosphate‐dependent changes in membrane potential, increased steadily over 4 to 7 d and both were inversely related to the internal phosphate concentrations in roots and shoots. When phosphate was resupplied to phosphate‐starved plants, the internal phosphate concentration and APT1/APT2 expression in roots were restored to control levels within 1 d whereas phosphate uptake took several days to decline to control rates. The increased expression of APT1/ATP2 genes when phosphate supply is restricted, and its close relationship with the internal phosphate concentrations in the root, provides evidence that phosphate uptake in Arabidopsis is controlled, at least in part, by the synthesis of transporter proteins as a result of increased transcription of phosphate transporter genes.
Sucrose‐phosphate synthase responds differently to source‐sink relations and to photosynthetic rates: Lolium perenne L. growing at elevated pCO2 in the field
Authors: Isopp H. , Frehner M. , Long S. P. , Nösberger J.
Published: March 2003

Lolium perenne, a main component species in managed grassland, is well adapted to defoliation, fertilization, and regrowth cycles; and hence, to changes in the assimilatory carbon source‐sink ratio. In the Swiss Free Air CO2 Enrichment experiment the source‐sink ratio is (i) increased by elevated partial pressure of CO2 (pCO2), (ii) decreased by enhanced carbon use under high N fertilization, and (iii) gradually increased during regrowth after defoliation. Since sucrose synthesis plays a central role in leaf carbohydrate metabolism in this fructan‐accumulating species, we investigated how sucrose‐phosphate synthase (SPS) responds to the differing assimilatory carbon fluxes and source‐sink ratios in the field. Assimilatory carbon flux, as estimated by leaf gas exchange, strongly depended on pCO2. Surprisingly, the SPS content per leaf area did not increase with pCO2, but increased with N fertilization. During later regrowth, when a dense canopy had formed, the SPS content decreased; in particular, SPS was decreased at high N under elevated pCO2. Further, the higher assimilatory carbon flux through SPS at elevated pCO2 was accompanied by a higher activation state of SPS. The SPS content correlated very strongly with the ratio of free sucrose to free amino acid in leaves, which represents the carbon source‐sink ratio. Hence, SPS content in L. perenne appears to be regulated by the current, strongly nitrogen‐dependent, source‐sink relation.
Expression of pH‐sensitive green fluorescent protein in Arabidopsis thaliana
Authors: Moseyko N. , Feldman L. J.
Published: March 2003

This is the first report on using green fluorescent protein (GFP) as a pH reporter in plants. Proton fluxes and pH regulation play important roles in plant cellular activity and therefore, it would be extremely helpful to have a plant gene reporter system for rapid, non‐invasive visualization of intracellular pH changes. In order to develop such a system, we constructed three vectors for transient and stable transformation of plant cells with a pH‐sensitive derivative of green fluorescent protein. Using these vectors, transgenic Arabidopsis thaliana and tobacco plants were produced. Here the application of pH‐sensitive GFP technology in plants is described and, for the first time, the visualization of pH gradients between different developmental compartments in intact whole‐root tissues of A. thaliana is reported. The utility of pH‐sensitive GFP in revealing rapid, environmentally induced changes in cytoplasmic pH in roots is also demonstrated.
Sexual reproduction of Lolium perenne L. and Trifolium repens L. under free air CO2 enrichment (FACE) at two levels of nitrogen application
Authors: Wagner J. , Lüscher A. , Hillebrand C. , Kobald B. , Spitaler N. , Larcher W.
Published: March 2003

Field experiments in managed grassland have shown that the response of vegetative growth to elevated CO2 is nitrogen‐dependent in grasses, but independent in N2‐fixing legumes. In the present study, we tested whether this is also true for reproduction. We evaluated reproductive growth, flowering phenology, seed development, reproductive success and seed germination in the grass Lolium perenne L. and the legume Trifolium repens L., growing in monocultures in a free air carbon dioxide enrichment (FACE) system at ambient (35 Pa) and elevated (60 Pa) partial pressure of CO2 and two levels of nitrogen fertilization (14 and 56 g N m−2 a−1). In both species, elevated CO2 had no significant effect on sexual reproduction. In L. perenne, reproduction was mainly nitrogen‐dependent. The weak interactions between CO2 and mineral N supply (13% more flowers and 8% more grains per spike at high N, 7% less flowers and 8% less grains at low N) were not significant. Under elevated CO2, grain maturation was slightly enhanced and grain weight tended to decrease. No influence could be ascertained in the date of anthesis, the temporal pattern of grain growth, the rate of grain abortion and germination. Trifolium repens, grown under CO2 enrichment at both levels of N fertilization, flowered 10 d earlier, tended to form more inflorescences per ground area and more flowers (8–12%) and seeds (>18%) per inflorescence than at ambient CO2. The temporal pattern of seed growth was about the same in all treatments; embryo development, however, was accelerated in fumigated plants. The number of aborted seeds per pod, seed size, thousand‐seed weight and germinability did not show any influence of CO2. Fumigated plants at high N were attacked slightly more frequently by seed‐eating weevils, which lowered the seed output per pod. In summary, the reproductive response of L. perenne and T. repens to CO2 enrichment on the flower and inflorescence level was far weaker than expected from the results on vegetative growth.
Contribution of the UV component of natural sunlight to photoinhibition of photosynthesis in six species of subtidal brown and red seaweeds
Authors: Dring M. J. , Wagner A. , Lüning K.
Published: March 2003

Field‐collected specimens of three species of Laminaria and three species of subtidal red algae (Delesseria sanguinea, Plocamium cartilagineum and Phyllophora pseudoceranoides) were exposed to natural summer sunlight on Helgoland (southern North Sea) for up to 4 h at 15 °C. Dark‐adapted variable fluorescence (Fv : Fm) was measured immediately after these treatments, and following 6, 24 and 48 h of recovery in moderate irradiances of white light. The response of plants to the full spectrum of natural sunlight was compared with that to PAR alone, UV‐A + visible, UV‐A + UV‐B, or UV‐A alone. The Fv : Fm values of all species were reduced to minimal values after 4 h in all of these treatments, but those of the more resistant species (Laminaria spp. and P. pseudoceranoides) were higher after shorter exposures to UV radiation alone than to PAR with or without UV. The recovery of Fv : Fm in all species was also more rapid in the two treatments that contained UV radiation alone than in those that included PAR. These results suggest that it is the high irradiances of PAR in natural sunlight which are responsible for the photoinhibition of photosynthesis of subtidal seaweeds and that the current ambient irradiances of UV radiation (either UV‐B or UV‐A) in northern temperate latitudes would not contribute significantly to this photoinhibition.
Characterization of the phosphatase activities of mosses in relation to their environment
Authors: Turner B. L. , Baxter R. , Ellwood N. T. W. , Whitton B. A.
Published: March 2003

Phosphatase activities and environmental features were characterized for 12 terrestrial and aquatic mosses in upland northern England, along with four species sampled from subarctic Sweden. Phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities of shoot tips were measured using para‐nitrophenyl phosphate (p‐NPP) and bis‐pNPP. All species showed PMEase activity, but not all showed PDEase activity. The mean pH optimum was 5·0 for PMEase and 5·7 for PDEase. The kinetic parameters Km and Vmax were calculated from three linear transformations of the Michaelis–Menten equation. The mean Km values of the mosses ranged between 77 and 468 µm for PMEase and 26 and 414 µm for PDEase. The corresponding Vmax values were 0·6–205 µmol pNP g−1 DW h−1 for PMEase and 1·4–110 µmol pNP g−1 DW h−1 for PDEase. Mosses from Sweden displayed greater Km and smaller Vmax values than those from England. The aquatics Fontinalis antipyretica and Rhynchostegium riparioides displayed two‐phase kinetics for PMEase and PDEase, with Km and Vmax being dependent on substrate concentration. Staining suggested that PMEase activity was located in the cell wall of most mosses. Phosphatase assays provide a rapid method for screening environmental nutrient status and a standard procedure is recommended.
Hydraulic properties and freezing‐induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitats
Authors: Cavender‐Bares J. , Holbrook N. M.
Published: March 2003

We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species’ habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co‐ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze–thaw‐induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies.
Analysis of carbohydrate metabolism of CPD antisense plants and the brassinosteroid‐deficient cbb1 mutant
Authors: Schlüter U. , Köpke D. , Altmann T. , Müssig C.
Published: March 2003

Brassinosteroids (BRs) are essential regulators of growth and development. BR‐deficient mutants such as cpd/cbb3 and dwf4 display extreme dwarfism due to a failure in cell elongation. To avoid the severe pleiotropic effects caused by the extreme growth defect, transgenic Arabidopsis lines carrying a construct for antisense inhibition of CPD gene expression were established and subjected to physiological analysis. The CPD‐antisense (α‐CPD) lines display characteristic phenotypic alterations of BR‐deficient plants such as reduced stem and petiole growth, smaller leaves, and a slightly delayed development. The observed changes are intermediate between the corresponding loss‐of‐function mutant (cbb3) and wild‐type plants. In the present study, the primary carbon metabolism of the transgenic lines as well as the BR‐deficient cbb1 (dwf1‐6/dim) mutant was analysed. Gas exchange measurements indicated a reduced assimilatory capacity of the α‐CPD plants. Soil‐grown α‐CPD as well as cbb1 (dwf1‐6) mutant plants show a clear reduction in starch content. The metabolic alterations are accompanied by altered enzyme activities such as reduced invertase and cytosolic β‐amylase activity, and altered expression patterns of genes such as Atbfruct1, Asus1, and ct‐Bmy (encoding a cell wall invertase, sucrose synthase, and plastidic β‐amylase, respectively). The impaired carbon assimilation, as well as the altered enzyme activities and gene expression patterns in the α‐CPD and cbb1 (dwf1‐6) plants, demonstrate the necessity of normal CPD and DIM expression for proper carbon uptake and metabolism and may point to an essential function of BRs. The impaired growth of BR‐deficient plants may be (at least in part) due to reduced photosynthesis.
DNA damage and photosynthesis in Antarctic and Arctic Sanionia uncinata (Hedw.) Loeske under ambient and enhanced levels of UV‐B radiation
Authors: LUD D. , MOERDIJK T. C. W. , VAN DE POLL W. H. , BUMA A. G. J. , HUISKES A. H. L.
Published: March 2003

The response of the bipolar moss Sanionia uncinata (Hedw.) Loeske to ambient and enhanced UV‐B radiation was investigated at an Antarctic (Léonie Island, 67°35′ S, 68°20′ W) and an Arctic (Ny‐Alesund, 78°55′ N, 11°56′ E) site, which differed in ambient UV‐B radiation (UV‐BR: 280–320 nm) levels. The UV‐BR effects on DNA damage and photosynthesis were investigated in two types of outdoor experiments. First of all, sections of turf of S. uncinata were collected in an Arctic and Antarctic field site and exposed outdoors to ambient and enhanced UV‐BR for 2 d using UV‐B Mini‐lamps. During these experiments, chlorophyll a fluorescence, chlorophyll concentration and cyclobutyl pyrimidine dimer (CPD) formation were measured. Secondly, at the Antarctic site, a long‐term filter experiment was conducted to study the effect of ambient UV‐BR on growth and biomass production. Additionally, sections of moss turf collected at both the Antarctic and the Arctic site were exposed to UV‐BR in a growth chamber to study induction and repair of CPDs under controlled conditions. At the Antarctic site, a summer midday maximum of 2·1 W m−2 of UV‐BR did not significantly affect effective quantum yield (ΔF/Fm′) and the ratio of variable to maximal fluorescence (Fv/Fm). The same was found for samples of S. uncinata exposed at the Arctic site, where summer midday maxima of UV‐BR were about 50% lower than at the Antarctic site. Exposure to natural UV‐BR in summer did not increase CPD values significantly at both sites. Although the photosynthetic activity remained largely unaffected by UV‐B enhancement, DNA damage clearly increased as a result of UV‐B enhancement at both sites. However, DNA damage induced during the day by UV‐B enhancement was repaired overnight at both sites. Results from the long‐term filter experiment at the Antarctic site indicated that branching of S. uncinata was reduced by reduction of ambient summer levels of UV‐BR, whereas biomass production was not affected. Exposure of specimens collected from both sites to UV‐BR in a growth chamber indicated that Antarctic and Arctic S. uncinata did not differ in UV‐BR‐induced DNA damage. It was concluded that S. uncinata from both the Antarctic and the Arctic site is well adapted to ambient levels of UV‐BR.
Symptoms, aetiology and serological analysis of sweet potato virus disease in Uganda
Authors: Gibson R. W. , Mpembe I. , Alicai T. , Carey E. E. , Mwanga R. O. M. , Seal S. E. , Vetten H. J.
Published: March 2003

Sweet potato virus disease (SPVD) is the name used to describe a range of severe symptoms in different cultivars of sweet potato, comprising overall plant stunting combined with leaf narrowing and distortion, and chlorosis, mosaic or vein‐clearing. Affected plants of various cultivars were collected from several regions of Uganda. All samples contained the aphid‐borne sweet potato feathery mottle potyvirus (SPFMV) and almost all contained the whitefly‐borne sweet potato chlorotic stunt closterovirus (SPCSV). SPCSV was detected by a mix of monoclonal antibodies (MAb) previously shown to react only to a Kenyan isolate of SPCSV, but not by a mixture of MAb that detected SPCSV isolates from Nigeria and other countries. Sweet potato chlorotic fleck virus (SPCFV) and sweet potato mild mottle ipomovirus (SPMMV) were seldom detected in SPVD‐affected plants, while sweet potato latent virus (SPLV) was never detected. Isolates of SPFMV and SPCSV obtained by insect transmissions together induced typical symptoms of SPVD when graft‐inoculated to virus‐free sweet potato. SPCSV alone caused stunting and either purpling or yellowing of middle and lower leaves when graft‐inoculated to virus‐free plants of two cultivars. Similarly diseased naturally inoculated field plants were shown consistently to contain SPCSV. Both this disease and SPVD spread rapidly in a sweet potato crop.
Suppression of clubroot formation in Chinese cabbage by the root endophytic fungus,Heteroconium chaetospira
Authors: Narisawa K. , Tokumasu S. , Hashiba T.
Published: March 2003

Root‐colonizing fungi were isolated from a total of 663 root segments of Chinese cabbage plants grown in soils collected from wheat, rape, Chinese cabbage, and napier grass fields. Most of the 322 isolates were from the wheat field soil and comprised 18 genera and two septate fungal groups. Hyaline and dark septate fungi accounted for approximately half the isolates from the wheat field soil. Sixteen isolates almost completely suppressed clubroot in sterile soil. Amongst these 16 isolates, two fromHeteroconium chaetospirawere also effective in nonsterile soil. Chinese cabbage seedlings from seed treated with these two isolates appeared healthy, and inoculation with one isolate promoted growth. Hyphae of the fungus covered the root surface and extensively colonized the inner cortical tissues.
Development of excised shoot and root assays for in vitro evaluation of Banksia species for response to Phytophthora species
Authors: Tynan K. M. , Scott E. S. , Sedgley M.
Published: March 2003

Excised shoot and root assays were evaluated for routine screening for Phytophthora resistance or tolerance in a Banksia breeding programme. An excised root assay provided useful information on the response of 15 Banksia species to Phytophthora cinnamomi and P. citricola. Roots were excised from 9‐ to 12‐month‐old plants, inoculated with plugs of mycelium, and sampled to establish the extent of colonization. Species susceptibility, expressed as the extent of root colonization at day 8, gave good agreement with previously published results obtained for plants inoculated in a shadehouse containment facility. This assay also showed differences in susceptibility among individual plants of B. baxteri and B. coccinea. An excised shoot assay was considered unsuitable for routine screening because lesion development in 16 species was found to be inconsistent when performed over 3 years. Preliminary evaluation of an assay using micropropagated shoots is reported.