bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of respiration in Locusta migratoria nymphs when feeding
Authors: Gouveia Scott M. , Simpson S.T.ephen J. , Raubenheimer David , Zanotto Flavia P. 
Published: March 2003

SummaryFlow‐through respirometry was used to investigate patterns of respiration of fifth‐instar Locusta migratoria L. nymphs fed a chemically defined, synthetic food. Each animal was recorded for up to 2.7 h, during which they had access to food and water ad libitum, and at least one meal was taken. The start of feeding was coincident with a sudden and rapid rise in respiration. Both carbon dioxide (CO2) production and oxygen (O2) consumption rose, the traces for the two gasses showing a high degree of alignment. The end of a meal correlated with a sudden and rapid decrease in respiratory rate towards resting levels. When feeding was interrupted by an intra‐meal pause, respiratory rate tended to drop marginally and then stabilize, before rising rapidly upon the resumption of feeding within the meal. Maximal rates of respiration during feeding represented a 3–4‐fold increase over those at rest. Walking and climbing within the chamber were not associated with any noticeable change in respiratory rate above baseline. When locusts were quiescent between feeding episodes, respiration was steady and continuous, rather than discontinuous. Possible causes for large changes in respiration during feeding are discussed.
The effect of host acceptability on oviposition and egg accumulation by the small white butterfly, Pieris rapae
Authors: Hopkins Richard J. , Van Loon Joop J. A. 
Published: March 2003

SummaryThe influence of host‐plant acceptability on oviposition rate, egg load, internal fat storage and longevity was studied in the small white butterfly, Pieris rapae L. (Lepidoptera: Pieridae). Newly emerged females and males were presented with either cabbage (Brassica oleracea L. var. gemmifera), which is a highly acceptable host for the small white, or wallflower (Cheiranthus cheiri L.), which is much less acceptable for oviposition. Individuals were dissected when 3, 6 and 9‐days‐old. Females kept on cabbage contained fewer mature eggs than those kept on wallflower and there was no change in the load of mature eggs over the time course studied. The number of immature eggs carried did not vary with host plant species, but did fall significantly between days 6 and 9. The body fat content of individuals declined with increasing age, but the decline was slower for individuals kept on the host of low acceptability. Individuals that were allowed to spend their natural lifespan on cabbage showed similar oviposition patterns over time, where the oviposition rate started high and gradually reduced until death. However, considerable differences in oviposition pattern were found in individuals kept on wallflower, varying from that found on cabbage to no oviposition at all. The implications of these findings are discussed in the light of existing oviposition theories. This leads to the conclusion that in one species the premises of existing theories on optimization of oviposition are not mutually exclusive but rather play in concert.
Behavioural response of aphids to the alarm pheromone component (E )‐β‐farnesene in the field
Authors: Jing‐Gong Xiangyu , Feng Zhang , Yu‐Ling Fang , Wei Kan , Guang‐Xue Zhang , Zhong‐Ning Zhang 
Published: March 2003

Abstract.The alarm response of aphids to (E)‐β‐farnesene was examined for 59 species in the subfamilies Aphididae, Callaphididae, Chaitophoridae and Lachnidae, in the field. Forty‐one aphid species responded to (E)‐β‐farnesene at a dosage of 1 ng and/or 10 ng; however, 18 species did not. Myrmecophilous aphids did not react as extensively or strongly as non‐myrmecophilous aphids. The response of aphids to (E)‐β‐farnesene was related to host‐plant species.
Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*
Authors: Hietz P. , Wanek W. , Popp M. 
Published: March 2003

ABSTRACTThe foliar content of nitrogen and the relative abundances of 13C and 15N were analysed in vascular epiphytes collected from six sites along an altitudinal gradient from tropical dry forests to humid montane forests in eastern Mexico. The proportion of epiphyte species showing crassulacean acid metabolism (CAM) (atmospheric bromeliads, thick‐leaved orchids, Cactaceae, and Crassulaceae) decreased with increasing elevation and precipitation from 58 to 6%. Atmospheric bromeliads, almost all of which had δ13C values indicating CAM, were more depleted in 15N (x=−10·9‰± 2·11) than the C3 bromeliads which form water‐storing tanks (−6·05‰± 2·26). As there was no difference in δ15N values between C3 and CAM orchids, the difference in bromeliads was not related to photosynthetic pathways but to different nitrogen sources. While epiphytes with strong 15N depletion appear to obtain their nitrogen mainly from direct atmospheric deposition, others have access to nitrogen in intercepted water and from organic matter decomposing on branches and in their phytotelmata. Bromeliads and succulent orchids had a lower foliar nitrogen content than thin‐leaved orchids, ferns and Piperaceae. Ground‐rooted hemi‐epiphytes exhibited the highest nitrogen contents and δ15N values.
Utilization of O2 in the metabolic optimization of C4 photosynthesis
Authors: Maroco J. P. , Edwards M. S. B. Ku & G. E. , Edwards G. E. 
Published: March 2003

ABSTRACTThe combined effects of O2 on net rates of photosynthesis, photosystem II activity, steady‐state pool size of key metabolites of photosynthetic metabolism in the C4 pathway, C3 pathway and C2 photorespiratory cycle and on growth were evaluated in the C4 species Amaranthus edulis and the C3 species Flaveria pringlei. Increasing O2 reduced net CO2 assimilation in F. pringlei due to an increased flux of C through the photorespiratory pathway. However, in A. edulis increasing O2 up to 5–10% stimulated photosynthesis. Analysis of the pool size of key metabolites in A. edulis suggests that while there is some O2 dependent photorespiration, O2 is required for maximizing C4 cycle activity to concentrate CO2 in bundle sheath cells. Therefore, the response of net photosynthesis to O2 in C4 plants may result from the balance of these two opposing effects. Under 21 versus 5% O2, growth of A. edulis was stimulated about 30% whereas that of F. pringlei was inhibited about 40%.
Incomplete 13C labelling of α‐pinene content of Quercus ilex leaves and appearance of unlabelled C in α‐pinene emission in the dark
Authors: Loreto F. , Ciccioli P. , Brancaleoni E. , Frattoni M. , Delfine S. 
Published: March 2003

ABSTRACT α‐Pinene is formed in and emitted by Quercus ilex leaves. The carbon emitted as α‐pinene is rapidly and totally labelled by 13C in CO2 in air, but α‐pinene contained in the leaf shows a fraction of completely unlabelled carbon even after long exposures to air containing only 13CO2. When the labelled leaf is darkened, α‐pinene emission drops but is still measurable for about 10 h, and carbon becomes partially unlabelled. After an 11 h darkening the α‐pinene content is still as high as in the light but the carbon is mostly unlabelled. If the leaf is re‐illuminated but photosynthesis is inhibited by removing CO2 and lowering O2, a burst of emission occurs and the content of α‐pinene is depleted. Our experiments suggest that a pool of α‐pinene which is not directly generated by photosynthesis intermediates exists. Since this pool does not contribute relevantly to the emission in the light, we hypothesize that it is inhibited in the light and spatially located in a different compartment from chloroplasts. As we discuss, glycolysis in the cytoplasm and leucine catabolism in the mitochondria are both possible extra‐chloroplasts sources of carbon for isoprenoids.
The isolation of genes from the resurrection grass Sporobolus stapfianus which are induced during severe drought stress
Authors: Neale A. D. , Blomstedt C. K. , Bronson P. , Le T.‐N. , Guthridge K. , Evans J. , Gaff D. F. , Hamill J. D. 
Published: March 2003

ABSTRACTA modification of the ‘cold plaque’ screening technique (Hodge et al., Plant Journal1992, 2, 257–260) was used to screen a cDNA library constructed from drought‐stressed leaf tissue of the desiccation tolerant (‘resurrection’) grass Sporobolus stapfianus. This technique allowed a large number of clones representing genes expressed at low abundance to be isolated. An examination of expression profiles revealed that several of these genes are induced in desiccation‐tolerant tissue experiencing severe drought stress. Further characterization indicated that the gene products encoded include an eIF1 protein translation initiation factor and a glycine‐ and proline‐rich protein which have not previously been associated with drought stress. In addition, genes encoding a serine/threonine phosphatase type 2C, a tonoplast‐intrinsic protein (TIP) and an early light‐inducible protein (ELIP) were isolated. A number of these genes are expressed differentially in desiccation‐tolerant and desiccation‐sensitive tissues, suggesting that they may be associated with the desiccation tolerance response of S. stapfianus. The results indicate that there may be unique gene regulation processes occurring during induction of desiccation tolerance in resurrection plants which allow different drought‐responsive genes to be selectively expressed at successive levels of water loss.
Late‐stage canopy tree species with extremely low δ13C and high stomatal sensitivity to seasonal soil drought in the tropical rainforest of French Guiana
Authors: Bonal D. , Barigah T. S. , Granier A. , Guehl J. M. 
Published: March 2003

ABSTRACTWe assessed the daily time‐courses of CO2 assimilation rate (A), leaf transpiration rate (E), stomatal conductance for water vapour (gs), leaf water potential (Ψw) and tree transpiration in a wet and a dry season for three late‐stage canopy rainforest tree species in French Guiana differing in leaf carbon isotope composition (δ13C). The lower sunlit leaf δ13C values found in Virola surinamensis (− 29·9‰) and in Diplotropis purpurea (− 30·9‰), two light‐demanding species, as compared to Eperua falcata (− 28·6‰), a shade‐semi‐tolerant species, were clearly associated with higher maximum gs values of sunlit leaves in the two former species. These two species were also characterized by a high sensitivity of gs, sap flow density (Ju) and canopy conductance (gc) to seasonal soil drought, allowing maintenance of high midday Ψw values in the dry season. The data for Diplotropis provided an original picture of increasing midday Ψw with increasing soil drought. In Virola, stomata were extremely sensitive to seasonal soil drought, leading to a dramatic decrease in leaf and tree transpiration in the dry season, whereas midday Ψw remained close to − 0·3 MPa. The mechanisms underlying such an extremely high sensitivity of stomata to soil drought remain unknown. In Eperua, gs of sunlit leaves was non‐responsive to seasonal drought, whereas Ju and gc were lower in the dry season. This suggests a higher stomatal sensitivity to seasonal drought in shaded leaves than in sunlit ones in this species.
The fate of [14C]glutamate and [14C]malate in birch roots is strongly modified under inoculation with Paxillus involutus
Authors: Blaudez D. , Botton B. , Dizengremel P. , Chalot M. 
Published: March 2003

ABSTRACTThe impact of inoculation with Paxillus involutus on the utilization of organic carbon compounds by birch roots was studied by feeding [14C]Glu or [14C]malate to the partners of the symbiosis, separately or in association, and by monitoring the subsequent distribution of 14C. Inoculation increased [14C]Glu and [14C]malate absorption capacities by up to eight and 17 times, respectively. Six‐ and 15‐d‐old mycorrhizal roots showed about four‐fold higher [14C]Glu and [14C]malate absorption capacities compared with 60‐d‐old mycorrhizal roots, suggesting that the early stages of mycorrhiza formation induced higher requirements for C skeletons. Moreover, the results demonstrated that inoculation strongly modified the fate of [14C]Glu and [14C]malate. It was demonstrated that exogenously supplied Glu and malate might serve as C skeletons for amino acid synthesis in mycorrhizal birch roots and in the free‐living fungus. Gln was the major 14C‐sink in mycorrhizal roots and in the free‐living P. involutus. In contrast, citrulline and insoluble compounds were the major 14C sinks in non‐mycorrhizal roots, whatever the 14C source. It was concluded that mycorrhiza formation leads to a profound alteration of the metabolic fate of exogenously supplied C compounds. The ecological significance of amino acid and organic acid utilization by mycorrhizal plants is further discussed.
Expressing the yeast HAL1 gene in tomato increases fruit yield and enhances K+/Na+ selectivity under salt stress
Authors: Rus A. M. , Estañ M. T. , Gisbert C. , Garcia‐Sogo B. , Serrano R. , Caro M. , Moreno V. , Bolarín M. C. 
Published: March 2003

AbstractThe yeast HAL1 gene facilitates K+/Na+ selectivity and salt tolerance of cells. Ectopic expression of HAL1 in transgenic tomato (Lycopersicon esculentum Mill.) plants minimized the reduction in fruit production caused by salt stress. Maintenance of fruit production by transgenic plants was correlated with enhanced growth under salt stress of calli derived from the plants. The HAL1 transgene enhanced water and K+ contents in both leaf calli and leaves in the presence of salt, which indicates that HAL1 functions in plants using a similar mechanism to that in yeast, namely by facilitating K+/Na+ selectivity under salt stress.
Plant water relations at elevated CO2– implications for water‐limited environments
Authors: Wullschleger S. D. , Tschaplinski T. J. , Norby R. J. 
Published: March 2003

AbstractLong‐term exposure of plants to elevated [CO2] leads to a number of growth and physiological effects, many of which are interpreted in the context of ameliorating the negative impacts of drought. However, despite considerable study, a clear picture in terms of the influence of elevated [CO2] on plant water relations and the role that these effects play in determining the response of plants to elevated [CO2] under water‐limited conditions has been slow to emerge. In this paper, four areas of research are examined that represent critical, yet uncertain, themes related to the response of plants to elevated [CO2] and drought. These include (1) fine‐root proliferation and implications for whole‐plant water uptake; (2) enhanced water‐use efficiency and consequences for drought tolerance; (3) reductions in stomatal conductance and impacts on leaf water potential; and (4) solute accumulation, osmotic adjustment and dehydration tolerance of leaves. A survey of the literature indicates that the growth of plants at elevated [CO2] can lead to conditions whereby plants maintain higher (less negative) leaf water potentials. The mechanisms that contribute to this effect are not fully known, although CO2‐induced reductions in stomatal conductance, increases in whole‐plant hydraulic conductance and osmotic adjustment may be important. Less understood are the interactive effects of elevated [CO2] and drought on fine‐root production and water‐use efficiency, and the contribution of these processes to plant growth in water‐limited environments. Increases in water‐use efficiency and reductions in water use can contribute to enhanced soil water content under elevated [CO2]. Herbaceous crops and grasslands are most responsive in this regard. The conservation of soil water at elevated [CO2] in other systems has been less studied, but in terms of maintaining growth or carbon gain during drought, the benefits of CO2‐induced improvements in soil water content appear relatively minor. Nonetheless, because even small effects of elevated [CO2] on plant and soil water relations can have important implications for ecosystems, we conclude that this area of research deserves continued investigation. Future studies that focus on cellular mechanisms of plant response to elevated [CO2] and drought are needed, as are whole‐plant investigations that emphasize the integration of processes throughout the soil–plant–atmosphere continuum. We suggest that the hydraulic principles that govern water transport provide an integrating framework that would allow CO2‐induced changes in stomatal conductance, leaf water potential, root growth and other processes to be uniquely evaluated within the context of whole‐plant hydraulic conductance and water transport efficiency.
Expression analysis of putative high‐affinity phosphate transporters in Chinese winter wheats
Authors: Davies T. G. E. , Ying J. , Xu Q. , Li Z. S. , Li J. , Gordon‐Weeks R. 
Published: March 2003

AbstractChina's soils tend to be phosphate deficient. Application of phosphorus fertilisers to the soil is yield and cost ineffective as much of the phosphate applied is rapidly locked‐in and is inaccessible to the crop. Chinese Institutes have established intensive wheat breeding programmes to generate wheat varieties that produce adequate yields and grain quality in such soils. Three such wheat cultivars have been identified with good performance characteristics in the field. These three cultivars are thought to harbour chromosome translocations that may confer enhanced phosphate scavenging abilities to the plants. The isolation and study of the expression of high‐affinity phosphate transporters in tissues of these wheats, in two of the donor wheatgrasses and in another widely planted Chinese wheat variety is presented and the first full‐length sequence of a wheat phosphate transporter and partial clones of several other putative phosphate transporters are reported. Relative quantitative reverse‐transcription – polymerase chain‐reaction was used to demonstrate that different phosphate transporters have different expression patterns within a given variety and respond differently to phosphate deprivation. The significance of the genetic background for these findings and for the different phosphate acquisition properties of the wheats under study is discussed.
Stomatal responses of Douglas‐fir seedlings to elevated carbon dioxide and temperature during the third and fourth years of exposure
Authors: Lewis J. D. , Lucash M. , Olszyk D. M. , Tingey D. T. 
Published: March 2003

AbstractTwo major components of climate change, increasing atmospheric [CO2] and increasing temperature, may substantially alter the effects of water availability to plants through effects on the rate of water loss from leaves. We examined the interactive effects of elevated [CO2] and temperature on seasonal patterns of stomatal conductance (gs), transpiration (E) and instantaneous transpiration efficiency (ITE) in Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings. Seedlings were grown in sunlit chambers at either ambient CO2 (AC) or ambient + 180 µmol mol−1 CO2 (EC), and at ambient temperature (AT) or ambient + 3·5 °C (ET) in a full‐factorial design. Needle gas exchange at the target growth conditions was measured approximately monthly over 21 months. Across the study period and across temperature treatments, growth in elevated [CO2] decreased E by an average of 12% and increased ITE by an average of 46%. The absolute reduction of E associated with elevated [CO2] significantly increased with seasonal increases in the needle‐to‐air vapour pressure deficit (D). Across CO2 treatments, growth in elevated temperature increased E an average of 37%, and did not affect ITE. Combined, growth in elevated [CO2] and elevated temperature increased E an average of 19% compared with the ACAT treatment. The CO2 supply and growth temperature did not significantly affect stomatal sensitivity to D or the relationship between gs and net photosynthetic rates. This study suggests that elevated [CO2] may not completely ameliorate the effect of elevated temperature on E, and that climate change may substantially alter needle‐level water loss and water use efficiency of Douglas‐fir seedlings.
Calcium oxalate and sulphate‐containing structures on the thallial surface of the lichenRamalina lacera: response to polluted air and simulated acid rain
Authors: GARTY J. , KUNIN P. , DELAREA J. , WEINER S. 
Published: March 2003

AbstractThe formation of calcium‐containing structures on the thallial surface of the lichenRamalina lacera(With.) J.R. Laund. in response to air pollution and to simulated acid rain, was studied inin situand transplanted thalli.In situthalli were collected from an unpolluted site and transplanted to heavily polluted and less polluted sites for a 10 month period. Additional thalli were treated either with double distilled water or with simulated acid rain. Scanning electron microscopy and infrared spectrometry revealed that thallial surfaces ofin situ R. lacerasamples collected in unpolluted sites were covered with two kinds of calcium oxalate crystals: whewellite and weddellite. These aggregates of calcium oxalate crystals appear to disintegrate and provide a crystal layer on the thallial surface. Infrared spectroscopy of powder scraped from thallial surfaces of transplants, retrieved from non‐polluted sites, showed the presence of whewellite and weddellite, whereas powders obtained from thalli retrieved from polluted sites contained whewellite, weddellite and gypsum. It is suggested that a certain fraction of the gypsum detected in crater‐like structures in transplants from polluted sites and in thalli treated with simulated acid rain is endogenous and should be considered a biomineral.
Xylem in early tracheophytes
Authors: EDWARDS D. 
Published: March 2003

ABSTRACTThe architecture of the presumed water‐conducting cells of the major lineages of early tracheophytes recorded in Silurian and Devonian rocks is reviewed, together with descriptions of further diverse types whose derivation remains uncertain. Evidence has been obtained from a wide gamut of fossils including coalified compressions, silicified, pyritized and calcium carbonate perimineralizations. Most of the cells, only a few having been unequivocally demonstrated to be tracheidal, have walls with two layers, the inner sometimes broadly similar to annular, spiral and scalariform secondary thickenings of extant xylem. There are, however, very few cases of identical construction and the fossil representatives show greater complexity and variety. Their walls are presumed to have been lignified, but the polymer has not yet been directly identified in the fossils. The implications of these wall architectures on the functioning of the cells in water conduction are briefly considered, as is their relevance to hypotheses on inter‐relationships of early tracheophytes and on tracheid ontogeny.
The possibility of factors other than phytoalexin accumulation preventing fungal growth in the incompatible interactions of soybean with Phytophthora megasperma f. sp. glycinea
Authors: Abe K. , Fujikawa E. , Takeuchi Y. , Takada Y. , Yamaoka N. 
Published: March 2003

Soybean (Glycine max) cv. Harosoy 63 is resistant to race 1 and susceptible to race 9 of Phytophthora megasperma f. sp. glycinea (Pmg). In detached primary leaves inoculated with zoospores, growth of race 1 was completely suppressed 16 h after inoculation, while race 9 was unaffected. The amount of the phytoalexin glyceollin that accumulated, however, was not significantly different in either the incompatible or compatible interaction 16 h after inoculation. At the circumference of the inoculated area, a slight accumulation of phytoalexin was observed only in the incompatible interaction 20 h or more after inoculation. Tolerance of race 9 to the phytoalexin was significantly higher than that of race 1 when the phytoalexin was added to agar. Moreover, race 9 degraded glyceollin faster than race 1. On leaves inoculated at separate points with either race, the lesion associated with race 9 never colonized areas inoculated with race 1. These results suggest that factor(s) other than the accumulation of phytoalexin in soybean tissue might cause cessation of growth of Pmg.