bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenotypic plasticity of body pigmentation inDrosophila: influence of a developmental thermoperiodic regime in two sibling species
Authors: Pétavy Georges , Moreteau Brigitte , Gibert Patricia , David Jean R. 
Published: March 2003

AbstractVariation of body pigmentation according to growth temperature was analysed in two European populations (Bordeaux and Cordoba) of the two sibling speciesDrosophila melanogaster(Meigen) andD. simulans(Sturtevant). Results obtained at constant temperatures were compared with those observed under alternating thermal regimes of various amplitudes and with a daily periodicity of 12–12 h. Abdominal pigmentation in segments 5, 6 and 7, and of their sum, was investigated in both species in females only. Thoracic trident pigmentation was studied in males and females but inDrosophila melanogasteronly.Thoracic pigmentation exhibited curvilinear convex reaction norms under constant conditions, with a darker pigmentation in the population (Bordeaux) living in a colder climate. No specific effects of alternating regimes were seen. For abdomen pigmentation, slightly different reaction norms were observed under constant conditions between Bordeaux and Cordoba strains. There were also slight differences between the two species. Alternating temperatures produced a significant decrease in average pigmentation, roughly proportional to the thermal amplitude.Alternating stressing conditions induced also an increase in the phenotypic variability of abdominal pigmentation, especially in segments 6 and 7. Finally, because an increase of growth temperature results in a monotonically decreasing reaction norm of both abdomen pigmentation in females and a size‐related trait, the wing/thorax ratio, we found a linear relationship between the two variables, with a very high overall correlation at constant temperatures (r = 0.99). The correlation was slightly less under alternating conditions, due to a broader dispersal of the experimental values around the regression lines.
Immune investment and sperm competition in a beetle
Authors: Drnevich Jenny M. , Barnes Andrew I. , Siva‐Jothy Michael T. 
Published: March 2003

AbstractIndividuals that invest more in immunity may not be able to invest as much in o\ther life history traits. The overall effects on fitness depend on the balance of investment in life history traits and unnecessary investment in immunity may lower fitness. Adult mealworm beetles (Tenebrio molitor L.) modulate their investment according to the perceived risk of infection as larvae; the amount of investment can be assessed by body coloration. This prophylactic investment in immunity can be used to assess the costs of investment when no immune challenge is present. Whether investment in immunity is traded off against sperm competitive ability, another important fitness trait in insects, was investigated. Males that had invested more in immunity (dark males) competed against males that had invested less (light males) for fertilization of offspring. Dark males did lose sperm precedence over time, whereas light males did not. However, this decrease in sperm offensive ability may not result in decreased fitness for darker males under normal female mating frequencies; the decrease in offspring did not occur for 1 week, but females that have constant access to males mate once a day, which would negate any long‐term effects of male mating order. Thus, prophylactic investment in immunity does not produce immediate reductions in a male's ability to gain fertilizations. The costs to immune investment may be born by other fitness traits in T. molitor.
Effects of maternal age on reproductive traits and fitness components of the offspring in the bruchid beetle, Callosobruchus chinensis (Coleoptera: Bruchidae)
Authors: Yanagi Shin‐Ichi , Miyatake Takahisa 
Published: March 2003

Abstract.In many insect species, the size and number of eggs decrease with maternal age. Thus, both the size and number of eggs must be considered to know the exact cost of reproduction with maternal age. The resource depletion hypothesis was examined in the bruchid beetle Callosobruchus chinensis. The hypothesis explains why the egg size decreases with maternal age based on the decline of the female's reproductive capacity. A decrease was found in reproductive effort (= egg size × the number of eggs) and the fitness component of offspring with maternal age. The effects of the female's nutritional status on the relationship between maternal age and the reproductive effort of females with and without food and water were also examined. The results indicate that the decrease in size and number of eggs with maternal age can be explained by the resource depletion hypothesis in C. chinensis.
Increased cytokinin levels in transgenic PSAG12–IPT tobacco plants have large direct and indirect effects on leaf senescence, photosynthesis and N partitioning
Authors: Jordi W. , Schapendonk A. , Davelaar E. , Stoopen G. M. , Pot C. S. , De Visser R. , Rhijn J. A. Van , Gan S. , Amasino R. M. 
Published: March 2003

ABSTRACTWe studied the impact of delayed leaf senescence on the functioning of plants growing under conditions of nitrogen remobilization. Interactions between cytokinin metabolism, Rubisco and protein levels, photosynthesis and plant nitrogen partitioning were studied in transgenic tobacco (Nicotiana tabacum L.) plants showing delayed leaf senescence through a novel type of enhanced cytokinin syn‐thesis, i.e. targeted to senescing leaves and negatively auto‐regulated (PSAG12–IPT), thus preventing developmental abnormalities. Plants were grown with growth‐limiting nitrogen supply. Compared to the wild‐type, endogenous levels of free zeatin (Z)‐ and Z riboside (ZR)‐type cytokinins were increased up to 15‐fold (total ZR up to 100‐fold) in senescing leaves, and twofold in younger leaves of PSAG12–IPT. In these plants, the senescence‐associated declines in N, protein and Rubisco levels and photosynthesis rates were delayed. Senescing leaves accumulated more (15N‐labelled) N than younger leaves, associated with reduced shoot N accumulation (–60%) and a partially inverted canopy N profile in PSAG12–IPT plants. While root N accumulation was not affected, N translocation to non‐senescing leaves was progressively reduced. We discuss potential consequences of these modified sink–source relations, associated with delayed leaf senescence, for plant productivity and the efficiency of utilization of light and minerals.
Dynamic changes in petiole specific conductivity in red maple (Acer rubrum L.), tulip tree (Liriodendron tulipifera L.) and northern fox grape (Vitis labrusca L.)
Authors: Zwieniecki Maciej A. , Hutyra Lucy , Thompson Matthew V. , Holbrook N. Michele 
Published: March 2003

ABSTRACTDiurnal variation in petiole specific hydraulic conductivity and simultaneous measurements of leaf water potential were recorded in red maple, tulip tree and fox grape. Petiole specific conductivity was determined from in situ measurements of water flow into the distal (leaf‐bearing) end of an attached petiole as a function of applied hydrostatic pressure and petiole dimensions. The hydraulic properties of the petiole dominated the measurements, indicating that this technique can be used for rapid estimates of petiole hydraulic conductivity. There was a significant decrease in petiole specific conductivity associated with increasingly more negative leaf water potentials in maple and tulip tree, but not in grape. Petiole specific conductivity increased during the afternoon while the plant was actively transpiring and the xylem sap was under tension. The recovery of petiole conductivity during the afternoon suggests that hydraulic conductivity reflects a dynamic balance between a loss of hydraulic conductivity with increasing water stress, and its restoration as tension within the xylem decreases. Three experimental manipulations were applied to red maple and tulip tree to examine the sensitivity of diurnal changes in petiole conductivity to various physiological perturbations. Both phloem girdling and application of HgCl2 to the transpiration stream resulted in a marked decrease in the degree to which petiole specific conductivity recovered as xylem tension relaxed during the afternoon. Delivery of a surfactant to the xylem, however, did not significantly alter the relation between leaf water potential and petiole hydraulic conductivity.
DNA endoreduplication in maize endosperm cells: the effect of exposure to short‐term high temperature
Authors: Engelen‐Eigles G. , Jones R. J. , Phillips R. L. 
Published: March 2003

ABSTRACTDNA endoreduplication in Zea mays L. (cv. A619 × W64A) endosperm peaks between 16 and 18 d after pollination (DAP). The physiological function of DNA endoreduplication is not known but it is believed to be important in maize kernel development. In the present study, we investigated how 2, 4 or 6 d of high temperature (35 °C) affected DNA endoreduplication and maize kernel development in comparison with control kernels grown at 25 °C. Data were collected on fresh weight (FW), nuclei number, mitotic index, and DNA endoreduplication. Maize endosperm FW and nuclei number were reduced by exposure to 4 or 6 d of high temperature. At 18 DAP, the 2 d high temperature treatment (HTT) caused a reduction in FW and nuclei number, but had no effect on DNA endoreduplication and average DNA content per endosperm. However, when the exposure to high temperature was increased to 4 or 6 d, FW, nuclei number and the magnitude of DNA endoreduplication were progressively reduced, and the peak mitotic index was delayed compared with the control endosperm. At 18 DAP, the 4 d treatment showed 54·7% of the cells were 3 or 6 C, whereas only 41·2% were 12 C or higher. Six days of high temperature also resulted in a reduction in endosperm FW, nuclei number and a delay in the peak of mitotic index. DNA endoreduplication occurred in the kernels exposed to this treatment, although the magnitude was severely reduced compared with the control kernels. Nuclear DNA content was highly correlated (r= 0·93) with kernel FW, suggesting an important role of DNA endoreduplication in determining endosperm FW. The data suggest that high temperature during endosperm cell division exerted negative effects on DNA endoreduplication by dramatically reducing the nuclei number, leaving fewer nuclei available for DNA endoreduplication. However, the data also suggest that prolonged exposure to high temperature restricts entry of mitotic cells into the endoreduplication phase of the cell cycle.
Degradation of phytochrome A and the high irradiance response in Arabidopsis: a kinetic analysis
Authors: Hennig Lars , Büche Claudia , Schäfer Eberhard 
Published: March 2003

ABSTRACTThe ability to respond to far‐red‐rich light is essential for seedlings germinating below dense canopies. Physiological and genetic studies have demonstrated that phytochrome A is the only photoreceptor mediating responses to far‐red light. However, all phytochromes including phytochrome A are believed to be activated by red light and to be inactivated by far‐red light. To address the fundamental question of why phytochrome A has its highest physiological activity at presumably inactivating wavelengths, we analysed light‐induced degradation of phytochrome A in Arabidopsis. Rate constants were obtained for all reaction events in a two‐step model of degradation. Based on biochemical data, the model includes a tagging mechanism preceding degradation. The parameterized model describes Pr accumulation, wavelength dependencies of degradation kinetics and steady‐state levels as well as Pfr‐induced Pr degradation. Subsequently, experimentally derived fluence rate response curves, action spectrum and response curves to dichromatic irradiation were compared to simulations based on the model of degradation. Two kinetically defined phytochrome subspecies, untagged Pfr and tagged Pr, have steady‐state levels closely matching the physiological response curves. Therefore, sensing of far‐red light by phytochrome A can be quantitatively explained based exclusively on regulated protein degradation.
Root hydrocarbons as potential markers for determining species composition
Authors: Dawson L. A. , Mayes R. W. , Elston D. A. , Smart T. S. 
Published: March 2003

ABSTRACTGrasslands can be a complex mixture of plant species. A method is described to allow the identification of both roots and shoots of five different grass species, thus permitting greater knowledge about whole plant allocation and competition in mixed pastures. The five species were Lolium perenne, Festuca ovina, Festuca rubra, Poa trivialis and Agrostis capillaris. N‐alkanes with odd‐numbers of carbon atoms in the chains predominate in plants and in the five grass species studied, concentrations of alkanes of chain length of C29, C31 and C33 were highest. Average concentrations of C27‐C33 alkanes in shoots and roots were 187 and 11 mg kg−1, respectively. This wide range of values required considerable modifications to the method of analysis, including expressing concentrations on an organic matter basis and scaling‐down the procedure. The n‐alkane concentrations in roots are different from those in shoots and therefore values from shoots cannot be used to predict the composition in roots. Using a canonical variate analysis, all five grass species could be separated using concentrations of C26, C31 and C33 values in the roots. The greatest difference occurred between A. capillaris and the others, whereas discrimination was least between the two Festuca species. Defoliation had contrasting effects on the concentration of a few n‐alkanes, but not in the n‐alkanes used to discriminate between grass species. Alkane analysis shows great potential as a method to quantify the species composition of the root biomass beneath mixed pasture species.
Stomatal acclimation to increased CO2 concentration in a Florida scrub oak species Quercus myrtifolia Willd
Authors: Lodge R. J. , Dijkstra P. , Drake B. G. , Morison J. I. L. 
Published: March 2003

ABSTRACTNative scrub‐oak communities in Florida were exposed for three seasons in open top chambers to present atmospheric [CO2] (approx. 350 μmol mol−1) and to high [CO2] (increased by 350 μmol mol−1). Stomatal and photosynthetic acclimation to high [CO2] of the dominant species Quercus myrtifolia was examined by leaf gas exchange of excised shoots. Stomatal conductance (gs) was approximately 40% lower in the high‐ compared to low‐[CO2]‐grown plants when measured at their respective growth concentrations. Reciprocal measurements of gs in both high‐ and low‐[CO2]‐grown plants showed that there was negative acclimation in the high‐[CO2]‐grown plants (9–16% reduction in gs when measured at 700 μmol mol−1), but these were small compared to those for net CO2 assimilation rate (A, 21–36%). Stomatal acclimation was more clearly evident in the curve of stomatal response to intercellular [CO2] (ci) which showed a reduction in stomatal sensitivity at low ci in the high‐[CO2]‐grown plants. Stomatal density showed no change in response to growth in high growth [CO2]. Long‐term stomatal and photosynthetic acclimation to growth in high [CO2] did not markedly change the 2·5‐ to 3‐fold increase in gas‐exchange‐derived water use efficiency caused by high [CO2].
CO2 transfer conductance, leaf structure and carbon isotope composition of Polygonum cuspidatum leaves from low and high altitudes
Authors: Kogami H. , Hanba Y. T. , Kibe T. , Terashima I. , Masuzawa T. 
Published: March 2003

ABSTRACTAnatomy and some physiological characteristics of the leaves in Polygonum cuspidatum Sieb. et Zucc., a dioecious clonal herb, were compared between two populations, one from a lowland in Shizuoka City (10 m above sea level), and another from a highland on Mt. Fuji (2500 m above sea level). Leaf mass per area (LMA) of the highland plants was about twice that of the lowland plants. The greater leaf thickness, thicker mesophyll cell walls and higher mesophyll cell density in the highland leaves contributed to the larger LMA. Although mesophyll area exposed to intercellular airspaces was greater in the highland leaves than in the lowland leaves by 30%, the surface area of chloroplasts facing intercellular airspaces was similar between these leaves. CO2 transfer conductance inside the leaf (gi) of the highland leaves (0·75 μmol m−2 s−1 Pa−1) is the lowest recorded for herbaceous plants and was only 40% of that in the lowland leaves. On the other hand, the difference in stomatal conductance was small. δ13C values in the leaf dry matter were greater in the highland leaves by 4‰. These data and the estimation of CO2 partial pressures in the intercellular air spaces and in the chloroplast suggested that the greater dry matter δ13C in the highland leaves, indicative of lower long‐term ratio of the chloroplast stroma to the ambient CO2 partial pressures, would be mainly attributed to their lower gi.
Does engineering abscisic acid biosynthesis in Nicotiana plumbaginifolia modify stomatal response to drought?
Authors: Borel C. , Frey A. , Marion‐Poll A. , Tardieu F. , Simonneau T. 
Published: March 2003

ABSTRACTThe consequences of manipulating abscisic acid (ABA) biosynthesis rates on stomatal response to drought were analysed in wild‐type, a full‐deficient mutant and four under‐producing transgenic lines of N. plumbaginifolia. The roles of ABA, xylem sap pH and leaf water potential were investigated under four experimental conditions: feeding detached leaves with varying ABA concentration; injecting exogenous ABA into well‐watered plants; and withholding irrigation on pot‐grown plants, either intact or grafted onto tobacco. Changes in ABA synthesis abilities among lines did not affect stomatal sensitivity to ABA concentration in the leaf xylem sap ([ABA]xyl), as evidenced with exogenous ABA supplies and natural increases of [ABA]xyl in grafted plants subjected to drought. The ABA‐deficient mutant, which is uncultivable under normal evaporative demand, was grafted onto tobacco stock and then presented the same stomatal response to [ABA]xyl as wild‐type and other lines. This reinforces the dominant role of ABA in controlling stomatal response to drought in N. plumbaginifolia whereas roles of leaf water potential and xylem sap pH were excluded under all studied conditions. However, when plants were submitted to soil drying onto their own roots, stomatal response to [ABA]xyl slightly differed among lines. It is suggested, consistently with all the results, that an additional root signal of soil drying modulates stomatal response to [ABA]xyl.
A novel approach to the in situ measurement of oxygen concentrations in the sapwood of woody plants
Authors: Gansert D. , Burgdorf M. , Lösch R. 
Published: March 2003

AbstractA novel technique for the physico‐chemical analysis of xylem sap by underwater access to the sapwood of trees is described. In situ measurements of dissolved oxygen in the sapwood are performed by combining this technique with a novel optical method for oxygen detection. In early spring, the oxygen concentration of the sapwood of Betula pendula was in the range of 80–230 µmol O2 L−1, corresponding to an oxygen deficit of 40–75% of air saturation. Oxygen concentration maxima and minima occurred early in the morning and in the afternoon, respectively, whereas xylem sap temperatures showed the reverse pattern. In the sapwood, hypoxia increased from the beginning of bud break until frondescence, when a deficit of 86% of air saturation marked the upper limit of oxygen depletion. There seemed to be no relationship between daily variations of oxygen concentration and xylem sap pressure. In summer, sap flow was a major determinant for the diurnal variation of dissolved oxygen concentration. Oxygen supply to the sapwood was determined by both radial influx into the trunk through intercellular gas spaces and transport of dissolved oxygen via xylem sap flow. Radial influx seemed to be favoured during night‐time, when the trunk was warmer than ambient air. During daytime, the hypoxia of the sapwood rose and increased sharply in the evening, when sap flow velocity approximated zero. High temperature in the sapwood enhanced the respiratory oxygen consumption of the wood parenchyma while the supply of dissolved oxygen via the transpiration stream became ineffective.
Rapid changes in cell wall pectic polysaccharides are closely associated with early stages of aerenchyma formation, a spatially localized form of programmed cell death in roots of maize (Zea maysL.) promoted by ethylene
Authors: Gunawardena A. H. L. A. N. , Pearce D. M. E. , Jackson M. B. , Hawes C. R. , Evans D. E. 
Published: March 2003

AbstractAerenchyma formation in roots of maize (Zea maysL.) involves programmed death of cortical cells that is promoted by exogenous ethylene (1 µL L−1) or by endogenous ethylene produced in response to external oxygen shortage (3%, v/v). In this study, evidence that degeneration of the cell wall accompanies apoptotic‐like changes previously observed in the cytoplasm and nucleus (Gunawardenaet al. Planta 212, 205–214, 2001), has been sought by examining de‐esterified pectins (revealed by monoclonal antibody JIM 5), and esterified pectins (revealed by monoclonal antibody JIM 7). In controls, de‐esterified wall pectins were found at the vertices of triangular junctions between cortical cells (untreated roots). Esterified pectins in control roots were present in the three walls bounding triangular cell‐to‐cell junctions. After treatment with 3% oxygen or 1 µL L−1ethylene, this pattern was lost but walls surrounding aerenchyma gas spaces became strongly stained. The results showed that cell wall changes commenced within 0·5 d and evidently were initiated by ethylene in parallel with cytoplasmic and nucleoplasmic events associated with classic intracellular processes of programmed cell death.
Water‐conducting properties of lipids during pollen hydration
Authors: Wolters‐Arts M. , Van Der Weerd L. , Van Aelst A. C. , Van Der Weerd J. , Van As H. , Mariani C. 
Published: March 2003

AbstractBased on the authors’ previous work an attempt has been made to study water flow in the lipid matrix during pollen hydration. The present study has demonstrated that in the presence of small amounts of water, the type of lipids used defined the time of hydration of pollen in vivo on the stigma and in vitro. Several approaches were used including cryo‐scanning electron microscopy, magnetic resonance imaging and Fourier transform infrared microspectroscopic imaging, with the purpose of detecting very small amounts of water. The results show that no water is detectable in the lipid matrix. It was observed and concluded that the water for pollen hydration accumulates as a thin layer at the contact side between pollen and stigma, during the normal process of pollination in plant species with a wet stigma. However, using the same species deprived of the stigma by cell ablation, it was shown that the layer of water observed in wild‐type plants is not necessary for pollen hydration.