bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrolysis of fructan in grasses: a β‐(2‐6)‐linkage specific fructan‐β‐fructosidase from stubble of Lolium perenne
Authors: MARX STEFAN P. , JOSEF NÖSBERGER , FREHNER MARCO 
Published: March 2003

SUMMARYSeveral different fructan and sucrose hydrolysing enzyme activities were induced in roots and stubble (mainly leaf sheaths) of Lolium perenne L. plants after defoliation. Among those activities, a fructan‐β‐fructosidase (EC 3.2.1.80) that hydrolyses predominantly β‐(2‐6)‐fructosyl‐fructose linkages (6‐FEH) was purified from the stubble. The use of the substrate 6,6‐kestotetraose and high‐performance anion‐exchange chromatography with pulsed amperometric detection allowed linkage‐specific screening and sensitive analysis of enzyme activity. A 6‐FEH was extensively purified to yield one protein band as revealed by one‐dimensional sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS–PAGE). The 6‐FEH was separated from the contaminating β‐(2‐1)‐linkage‐specific fructan‐β‐fructosidase and invertase activities (EC 3.1.2.26) by ammonium sulphate precipitation, lectin‐affinity, anion‐exchange and size‐exclusion chromatography. The purified 6‐FEH was a glycoprotein with an apparent molecular mass of 65000, as determined by size‐exclusion chromatography, and of 69000 by SDS–PAGE. The 6‐FEH had an activity optimum in the range of pH 5.1 to 5.6. Temperatures above 30°C affected the stability of the enzyme activity; however, its temperature stability was increased in the presence of 6,6‐kestotetraose. The purified 6‐FEH activity hydrolysed the β‐(2‐6)‐linkages in 6,6‐kestotetraose and (1&6)‐kestotetraose at rates five times faster than the β‐(2‐1)‐linkages in 1,1‐kestotetraose and (1&6)‐kestotetraose. Fructose up to 50 mM did not affect 6‐FEH activity; conversely, sucrose substantially inhibited the enzyme activity. Other disaccharides did not affect 6‐FEH. It is suggested that sucrose might modulate 6‐FEH activity in vivo.
Effects of litter on substrate conditions and growth of emergent macrophytes
Authors: VAN DER PUTTEN W. H. , PETERS B. A. M. , VAN DEN BERG M. S. 
Published: March 2003

summaryThree successive emergent macrophytes (Typha latifoliaL.,Phragmites australis(Cav.) Steudel andGlyceria maxima(Hartman) Holmbly) were each grown in substrates collected from three different zones of shoreline vegetation development (non‐vegetated sediment, the interface betweenT. latifoliaandP. australis, and degeneratingP. australis). The aim of the study was to assess whether accumulation of litter changes growth conditions ofP. australis, and to determine its effects on pre‐ and post successional plant species. The study was carried out by means of pot experiments in a glasshouse. Seedlings of the three species were cultured in fertilized and unfertilized substrates under both waterlogged and drained conditions.In its own litter, growth ofP. australiswas strongly reduced, compared with the productivity of plants in substrates from preceeding successional stages, and could not be compensated for by fertilization or soil drainage. The redox potential of the substrate was not strongly reduced and the sediment density was well above the critical level. Soil sterilization by gamma‐irradiation did not improve growth substantially, although there was some positive effect in unfertilized substrate. Phytotoxic compounds might have caused poor growth ofP. australisin its own litter.T. latifoliaandG. maximawere relatively less affected by theP. australislitter. The possible importance of litter accumulation on species replacement in shoreline vegetation is discussed. It is concluded that the accumulation of organic matter should be considered as a factor affecting spatio‐temporal processes in littoral vegetation owing to its specific impact on the functioning of individual dominant plant species.
Correlation between potassium efflux and copper sensitivity in 10 Arahidopsis ecotypes*
Authors: MURPHY ANGUS , TAIZ LINCOLN 
Published: March 2003

SUMMARYTo study the relationship between copper sensitivity and membrane permeability in Arabidopsis, the seedling growth rates (measured as root extension and f. wt increase) of 10 ecotypes with differing copper sensitivities were compared with their patterns of potassium efflux and copper uptake. At 36 h, inhibition of root extension in 40 μi Cu correlated well with K+ efflux (r= 0.96) and a decrease in osmolality (r= 0.96). By contrast, neither tissue osmolality nor K+ efflux correlated significantly with growth inhibition after 4 h Cu treatment. In detailed time‐course studies of two of the less sensitive ecotypes (Shadhara and Ws) and two of the more sensitive ecotypes (Berkeley and Limeport) in 20 μM Cu, growth, K+ retention and osmolality decreased rapidly during the first 4 h. Only the two less sensitive ecotypes recovered during the following 32 h. A similar pattern was observed with 40 μM Cu, except that growth inhibition was more marked. Interestingly, after 4 h the less sensitive ecotypes exhibited greater inhibition than the more sensitive. In time‐course measurements, the Cu contents of the four ecotypes were not significantly different when normalised on a f. wt basis. We conclude that variations in the metal sensitivities of Arabidopsis ecotypes are not due to constitutive differences in membrane permeability but, rather, to differences in the ability to reverse K+ efflux. The possibility that short‐term Cu‐induced K+‐leakage is regulated by channels rather than lipid oxidation is discussed.
Effect of the arbuscular mycorrhizal fungus Glomus fasciculatum on the uptake of amino nitrogen by Lolium perenne
Authors: CLIQUET JEAN BERNARD , MURRAY PHILIP J. , BOUCAUD JEAN 
Published: March 2003

summaryThe ability of ryegrass (Lolium perenne L.) to take up and utilize aspartic acid (Asp) and serine (Ser,), and the effect of colonization of the roots by the arbuscular mycorrhizal (AM) fungus Glomus fasciculatum (Thax. sensu Gerd.) were studied. The seedlings were grown under controlled conditions in a series of micro‐lysimeters. All plants were fed with a nutrient solution containing either nitrate, Asp or Ser as the sole N source. After 49 d, they were supplied with 15N labeled nitrate. Asp or Ser for 1 h and harvested.AM colonization increased the growth and total N content of the plants in all cases. Similarly, the amount of Asp or Ser taken up was higher in AM than in control plants. There were no differences in biomass production between the nitrate and Ser‐fed plants. However uptake rates were lower for Ser than for nitrate. Growth of the Asp‐fed plants was significantly less than the other two treatments, and uptake of 15N‐Asp was lower than uptake of 15N‐Ser. Analysis of 15N incorporation into the amino acids extracted from the roots suggests the hydrolysis of Ser followed by re‐assimilation of the resulting ammonia via the GS‐GOGAT cycle. There were no differences in the patterns of accumulation of amino acids in the root‐zone of control and AM‐ryegrass. The implication of these results for the pathway of nitrogen transfer between plants is discussed.
Allozyme diversity and genetic structure in South‐Western populations of heather, Calluna vulgaris
Authors: MAHY G. , VEKEMANS X. , JACQUEMART AL. , DE SLOOVER JR. 
Published: March 2003

summaryGenetic diversity, population genetic structure and gene flow in Calluna vulgaris (L.) Hull were assessed by means of seven allozyme loci scored in 18 populations from the South‐Western area of the species' range. Genetic diversity was lower (HT= 0.20) than reported for long‐lived widespread species but was characterized by a high number of alleles per locus (5.60 at the species level) of which more than 70% were rare. More than 95% of genetic variation was found at the intrapopulation level (GST= 0.047). High levels of past gene flow were inferred, based on the allozyme data (Nm= 5.2 from GST. Nm= 10.2 from the ‘private allele’ method). Calluna vulgaris exhibited several geographic patterns of genetic variation. Both cluster analysis, constructed with various genetic distances and principal components analysis showed that Spanish and Pyrenean populations were clearly different from those collected in the Massif Central and Belgium. Also, a trend for decreasing genetic diversity towards Northern populations was detected. These patterns might be related to the post‐glacial history of Calluna. In addition, it is shown that isolation by distance has played a role in the geographic shaping of genetic variation in this species.
The potential for the biological control of cavity‐spot disease of carrots, caused byPythium coloratum, by streptomycete and non‐streptomycete actinomycetes
Authors: EL‐TARABILY KHALED A. , HARDY GILES E. ST. J. , SIVASITHAMPARAM KRISHNAPILLAI , HUSSEIN ASSEM M. , KURTBÖKE D. IPEK 
Published: March 2003

summaryActinomycetes isolated from carrot rhizosphere were screened for theirin vitroandin vivoantagonism toPythium colorationVaartaja, a causal agent of cavity‐spot disease of carrots (Daucus carataL.). Forty‐five streptomycete and non‐streptomycete actinomycete isolates were screened forin vitroantagonism in a carrot bioassay. Of these, seven which reduced or prevented lesion formation were identified using cultural, morphological, physiological, biochemical and cell wall characteristics asStreptomyces janthimts, S. cinerochromogenes, Streptoverticilium netropsis, Actinomadura rubra, Actinoplanes philippinensis, Muromonospora carbonaceae, andStreptosporangium albidum.All seven isolates tested produced non‐volatile antifungal metabolites, but failed to produce inhibitory volatile compounds.Actinoplanef philippincnsisand M.carbonaceagrew epiphytically on the hyphae and oospores ofP. eoloratum.The external surface of the oospores of the pathogen was heavily colonized by both hyperparasites, their hyphae were found to coil tightly around the oospore wall, and frequently caused cytoplasmic collapse of oospores. Sporangia ofA. philippinensiswere often seen to emerge from the colonized hyphae and oospores ofP. eoloratum.None of the other actinomycete isolates showed hyperparasitism.All seven isolates significantly reduced the incidence of cavity spot in soil artificially infested with the pathogen in the glasshouse.Streptomyces janlhinusandStfepto. albidumwere the most effective in reducing the disease in inoculated plants. In addition, all the actinomycetes species exceptAc. rubraandM. carbonacea, in the presence or absence of the pathogen, significantly (P< 0.05) increased mean fresh root weight compared to the treatment which includedP. thoriumonly. This study shows that these actinomycetes have considerable potential for future use as biocontrol agents of cavity spot under natural field conditions. This is the first report of cavity‐spot disease of carrots being controlled by microbial antagonists, and is the first report of non‐streptomycete actinomycetes to control aPythiumdisease.
Elevated CO2 and tree root growth: contrasting responses in Fraxinus excelsior, Quercus petraea and Pinus sylvestris
Authors: CROOKSHANKS MEG , TAYLOR GAIL , BROADMEADOW MARK 
Published: March 2003

Root growth and respiration in elevated CO2 (700 μmol mol−1) was studied in three tree species, Fraxinus excelsior L., Quercus petraea. L. and Pinus sylvestris L. grown in open‐top chambers (OTCs) during a long‐term exposure (20 months), during which root systems were allowed to develop without restriction imposed by pots. Root growth, measured as root length using root in‐growth bags was increased significantly in trees exposed to elevated CO2, although the magnitude of the response differed considerably between species and with time of sampling, the greatest effect observed after 6 months in ash (ratio of elevated: ambient, e∶a; 3·40) and the smallest effect observed in oak (e∶a; 1·95). This was accompanied by changes in specific root length, with a significant decrease in all species after 6 months, suggesting that root diameter or root density were increased in elevated CO2. Increases in root length might have resulted from an acceleration in root cell expansion, since epidermal cell size was significantly increased in the zone of elongation in ash root tips (P<0·05).Contrasting effects of elevated CO2 were observed for root carbohydrates, with significant increases in soluble sugars for all species (P<0·05), but both increases and decreases in starch content were observed, depending on species, and producing a significant interaction between species and CO2 (P<0·001). Exposure to elevated CO2 increased the total root d. wt for whole trees of all three species after 8 months of exposure, although the magnitude of this effect, in contrast to the root in‐growth study, was greatest in Scots pine and smallest in ash. No significant effect of elevated CO2 was observed on the root∶shoot ratio. Further detailed analysis of whole root systems after 20 months confirmed that species differences in root responses to elevated CO2 were apparent, with increased coarse and fine root production in elevated CO2 for Scots pine and ash respectively. Lateral root number was increased in elevated CO2 for all species, as was mean root diameter. Root respiration rates were significantly reduced in elevated CO2 for all three species. These results provide firm evidence that exposure of trees to future CO2 concentrations will have large effects on root system development, growth, carbohydrate status and respiration. The magnitude and direction of such effects will differ, depending on species. The consequences of such responses for the three species studied are discussed.
The New Phytologist Forum
Authors: Ingram Jonathan 
Published: March 2003

New Phytologist has, throughout its history, been a forum for open debate – indeed, in his opening editorial (1902), Tansley referred to ‘easy communication and discussion’ as being the main ideas for the journal launch. The Internet now offers exciting new ways for sharing information, and this has challenged all information providers to reassess what they offer. It is our intention that the new Forum section in the journal should formalize our standing commitment, and encourage serious dialogue – through scientific commentary, correspondence and opinion.As the journal approaches its hundredth year, so the need for dialogue is stronger than ever. More and more science is published, making it harder, year on year, to keep abreast of important developments. Science is also global, making discussion confined to those within one country or economic bloc to be too restrictive. And as the pressure to publish is as strong as it has ever been, so the free flow of original and unorthodox ideas can too easily become stifled. New Phytologist, as a high‐impact, high‐quality journal, with its international scope and fierce independence – the Trust is not answerable to any society or commercial publisher – is a respected vehicle for such material. We invite you to participate, and to join us in helping the Forum to develop.
Evolution of metal hyperaccumulation and phytoremediation hype
Authors: Ernst Wilfried H. O. 
Published: March 2003

Cadmium accumulation and tolerance are discussed in a New Phytologist article by Krämer (2000), which comments
on a paper by Lombi et al. (2000). In this context, a number of additional points should be made, putting the role of humans in the evolution of metal resistance into context and emphasizing what is the ‘hype’ of phytoremediation.It is important that sites created by humans should not be overemphasized in considering the evolution of metal resistance. Plants resistant to heavy metals have their primary sites not on these, but on soils where ores are outcropping, the so‐called metalliferous or orogenic soils (Ernst, 1974). Over thousands of years, natural exposure to a surplus of various metals, depending on the mineralization process, has driven the evolution of metal resistance in many plant species under the local environmental conditions. Many publications have shown that Thlaspi caerulescens can hyperaccumulate Zn (e.g.
Vázquez et al., 1992), and accumulate other heavy metals
such as Cu and Pb depending on soil chemistry (e.g. Baker
et al., 1994). It has been known for more than 30 years that
T. caerulescens gives a good response to experimentally
supplied high Zn levels (Ernst, 1968). One of the ecological
effects of hyperaccumulation of heavy metals is a defence
against herbivorous insects (Boyd & Martens, 1994). This
effect is enhanced by a preferential accumulation of heavy
metals in the epidermal leaf layer (Heath et al., 1997).
Elevated CO2 and nitrogen supply alter leaf longevity of grassland species
Authors: Craine Joseph M. , Reich Peter B. 
Published: March 2003

Summary

The longevity of green leaf area for 10 grassland species was measured to establish whether elevated CO2 and N fertilization alter leaf longevity, an important determinant of ecosystem leaf area and ecosystem carbon gain.
Plants were selected from monocultures in their second year of growth in a field experiment that directly manipulated atmospheric CO2 (550 ppm and ambient) and nitrogen fertilization (4 g N m−2 and ambient). Leaves were censused biweekly over a 4‐month period.
Leaf longevity increased under elevated CO2 (+3.4 d, P = 0.03) and decreased under elevated N (−4.2 d, P = 0.03). Leaf longevity increased under elevated CO2 for C3 species only; there was no change in leaf longevity of C4 species under elevated CO2. For both CO2 and N, changes in leaf longevity were congruent with expectations based on observed changes in N cycling.
In addition to supplies of resources such as CO2 and N, site fertility and the development of ecoystem feedbacks appear to be important in determining leaf longevity.
Characterization of an Aux/IAA cDNA upregulated in Pinus pinaster roots in response to colonization by the ectomycorrhizal fungus Hebeloma cylindrosporum
Authors: Charvet‐Candela V. , Hitchin S. , Ernst D. , Sandermann H. , Marmeisse R. , Gay G. 
Published: March 2003

Summary• In an attempt to determine whether fungal auxin affects host plant gene expression during mycorrhizal formation, an auxin upregulated cDNA, Pp‐iaa88, was isolated by differential screening of a cDNA library made from auxin‐treated Pinus pinaster roots.• Pp‐iaa88 codes for a polypeptide that shares extensive homology to auxin‐inducible Aux/IAA proteins, which are supposed to act as transcription factors. Cycloheximide did not inhibit auxin‐induced mRNA accumulation, indicating that Pp‐iaa88 upregulation is a primary (direct) auxin response.• The level of Pp‐iaa88 transcripts in roots increased following inoculation with either an indoleacetic acid‐overproducing mutant or a wild‐type strain of the ectomycorrhizal fungus Hebeloma cylindrosporum. With both strains, mRNA accumulation was detectable as soon as fungal hyphae reached the root and it increased during differentiation of symbiotic structures. The kinetics of Pp‐iaa88 transcript accumulation was closely connected with the dynamics of symbiosis establishment and was more rapid with the mutant than with the wild‐type strain.• As a putative transcription factor expressed at the very early stages of symbiosis establishment, Pp‐iaa88 could play a key role in mycorrhizal formation.
Lichens respond to heavy metals by phytochelatin synthesis
Authors: Pawlik‐Skowrońska Barbara , Di Toppi Luigi Sanità , Favali Maria Augusta , Fossati Fabrizia , Pirszel Jacek , Skowroński Tadeusz 
Published: March 2003

Summary

The main aims of this paper are to investigate: if widespread lichen species ( Xanthoria parietina
,
Physconia grisea
and
Physcia adscendens , collected in Italy and Poland) exposed to cadmium (Cd), lead (Pb) and zinc (Zn) synthesize phytochelatins; whether phytochelatins are synthesized by the heterotrophic fungus (mycobiont) or by the photosynthetic alga (photobiont), or by both of the partners; and if there are significant differences in phytochelatin production in the same lichen species growing at different latitudes.
In the lichens investigated, Cd, Pb and Zn induced the biosynthesis of phytochelatins (PC 2
, PC
3
and PC
4
) and some DES‐GLYCIL derivatives. However, only the photobiont partners (the green microalgae of the genus
Trebouxia ) were capable of phytochelatin production and, by contrast, aposymbiotically grown mycobionts only produced glutathione.
The Cd‐exposed lichens grown in Italy produced significantly larger amounts of phytochelatins than the same species grown in Poland. An opposite trend was observed in Pb‐exposed lichens.
The trebouxioid lichens may gain an ecological advantage from their capability to counter heavy metal stress with prompt phytochelatin synthesis.
The effects of skirt lining properties on comfort and movement
Authors: Kawabata Hiroko , Obara Kazuyuki , Komiyama Hitomi , Narumi Taeko 
Published: March 2003

AbstractThis study was conducted to clarify the influences of the lining properties of skirts upon comfort and movement. The comfort of lining fabrics and real skirts with and without lining was rated by sensory tests on the basis of sensorial comfort on the skin and body movement. Actual body movements were investigated by motion analysis while the skirts were being worn. The results are described: (1) Comfort on the skin, movement and overall preference for the lining fabrics were evaluated by sensory testing, comparing skirts made with five kinds of lining fabrics. Conventional non‐stretch cupro lining was ranked first on the basis of smoothness and good feel to the skin. Two‐way stretch lining was also ranked highly in terms of ease of movement. We discuss how sensorial comfort on the skin and ease of movement related to overall preference for lining fabrics. (2) Sensory test of the actual skirts with and without lining clearly confirmed that lining played a role in improving comfort. (3) For a non‐stretch fabric skirt, conventional lining was ranked highly for good feel to the skin, and two‐way stretch lining was considered useful for ease of movement. There was no significant difference between the two lining fabrics in overall preference. (4) For a stretch fabric skirt, stretch lining is the most useful because it maintains easy extension of the outer fabric, thus allowing ease of body movement. (5) Motion analysis showed that a combination of knitted stretch skirts with stretch lining was the best for ease of movement. Comparing the sidelines and the hemline of the stretch fabric skirts demonstrated a better shape using lining.
Effect of growth phase on the subsequent growth kinetics of psychrotrophic bacteria of raw milk origin
Authors: Rowe Michael T , Dunstall George , Kilpatrick David , Wisdom G Brian 
Published: March 2003

Psychrotrophs isolated at days 1, 3 and 5 from refrigerated raw milk were monitored for growth kinetics using conductance when they had been inoculated during their lag, log and stationary growth phases. The results indicated that there was a more rapid change in the microflora during the initial stages of storage when the lag phases of the 1, 3 and 5 day isolates were analysed. There was also evidence of the ‘suicide response’. In addition, the fact that the stationary phase cells showed the greatest exponential growth rate may be a contributory factor to their selective advantage.