bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free amino acid, ammonium and nitrate concentrations in soil solutions of a grazed coastal marsh in relation to plant growth
Authors: Henry H. A. L. , Jefferies R. L. 
Published: March 2003

AbstractSoluble free amino acids, ammonium and nitrate ions as sources of nitrogen for plant growth were measured in soils of a coastal marsh grazed by snow geese in Manitoba, Canada. Amounts of nitrogen, primarily ammonium ions, increased in the latter half of the growing season and over winter, but fell to low values early in the growing season. Free amino acid concentrations relative to ammonium concentrations were highest during the period of rapid plant growth in early summer, especially in soils in the intertidal zone, where the median ratio of amino acid nitrogen to ammonium nitrogen was 0·36 and amino acid concentrations exceeded those of ammonium ions in 24% of samples. Amino acid profiles, which were dominated by alanine, proline and glutamic acid, were similar to goose faecal profiles. In a continuous flow hydroponic experiment conducted in the field, growth of the salt‐marsh grass, Puccinellia phryganodes, on glycine was similar to growth on ammonium ions at an equivalent concentration of nitrogen. When supplies of soil inorganic nitrogen are low, amino acids represent a potentially important source of nitrogen for the re‐growth of plants grazed by geese and amino acid uptake may be as high as 57% that of ammonium ions.
Diurnal changes in the concentrations of 2‐phenylethyl β‐D‐glucopyranoside and the corresponding volatile aglycone in the tissue and headspace of Trifolium repens L. florets
Authors: Jakobsen H. B. , Christensen L. P. 
Published: March 2003

AbstractDistinct synchronous diurnal rhythms were detected in the concentrations of phenethyl alcohol and phenethyl acetate in the tissue of blooming Trifolium repens florets. Corresponding rhythmic oscillations were observed for the same two compounds in the floral headspace. Maximum content of the volatiles in the tissue and headspace was observed 3–9 h after initiation of the photophase. The concentrations of phenethyl alcohol and phenethyl acetate in the tissue increased significantly during floral development. At full bloom the tissue contained amounts sufficient to support 2–3 h of emission. Several observations suggested that esterification of phenethyl alcohol was the source for phenethyl acetate. Trimethylsilyl derivatization and enzymatic hydrolysis of fractionated flower extracts identified 2‐phenylethyl β‐d‐glucopyranoside as the major glucoside in the florets. The pool of glucosides increased significantly during floral development and at full bloom 97% of the phenethyl alcohol was bound as glucoside. The concentration of 2‐phenylethyl β‐d‐glucopyranoside did not vary in a rhythmic diurnal manner. The dynamics among the diurnal rhythmic phenomena in the tissue and headspace and the fraction of volatiles bound as glucosides is discussed.
Effect of NO3‐ supply on N metabolism of potato plants (Solanum tuberosum L.) with special focus on the tubers
Authors: Mäck G. , Schjoerring J. K. 
Published: March 2003

AbstractThe response of the tubers to NO3– was studied in comparison to the other organs of Solanum tuberosum var. Sava, with special focus on: (a) whether tubers are capable of primary N assimilation; (b) whether N assimilation is stimulated by NO3–; and (c) whether primary N assimilation in tubers is important for tuber growth. NO3– reduction via nitrate reductase (NR; EC 1.6.6.1) and NH4+ assimilation via glutamine synthetase (GS; EC 6.3.1.2) occurred predominantly in the shoots, but up to 20% was contributed by the tubers under low‐NO3– conditions. NR activation was highest in tubers (up to 90%) and declined in all organs with increasing NO3– supply. NR and GS activity responded with a decline in tubers and roots as opposed to an increase in the shoots. This corresponded to relative organ growth: growth of tubers and roots was stimulated relative to that of shoots at a limiting NO3– supply. Absolute growth of all organs was stimulated by NO3–, whereas tuber number declined. The concentration of N compounds increased with NO3– supply in all organs: NO3– increased most dramatically in the shoots (81‐fold), free amino acids most markedly in the tubers (three‐fold). The amount of patatin and of the 22 kDa protein complex in the tuber reached a minimum when the amount of Rubisco in the shoot reached maximum as a response to NO3– supply. Tuber sucrose and starch increased by 40%, whereas glucose and fructose declined two‐fold as plant N status increased. It is concluded that tubers are potentially N autotroph organs with capacity for de novo synthesis of amino acids. Primary N assimilation in tubers, however, declines with increasing NO3– supply and is not of major importance for tuber growth.
Grass cells ingested by ruminants undergo autolysis which differs from senescence: implications for grass breeding targets and livestock production
Authors: Beha E. M. , Theodorou M. K. , Thomas B. J. , Kingston‐Smith A. H. 
Published: March 2003

AbstractIt is widely believed that the initial degradation of proteins contained in grazed forage is mediated by rumen micro‐organisms, but the authors’ recent work suggests that the plant cells themselves contribute to their own demise. In the present study the responses of Lolium perenne leaves to the rumen environment were investigated by using an in vitro system which simulates the main stresses of the rumen but from which rumen micro‐organisms were excluded. Degradation of leaf protein and the accumulation of amino acids in tissue and bathing medium occurred over a time‐scale that is relevant to rumen function, and in a near 1 : 1 ratio. Significant loss of nuclear material was observed after 6 h incubation and chloroplasts became morphologically more spherical as the incubation progressed. In situ localization suggested that ribulose 1,5 bisphosphate carboxylase/oxygenase was broken down within chloroplasts which from cytology were judged to be intact. We conclude from these data that plant metabolism may play a significant role in breaking down plant proteins within relatively intact organelles in the rumen. The determinations of chlorophyll content and cell viability revealed that the plant processes occurring in the simulated rumen were similar but not identical to those of natural senescence.
Discrimination of genes expressed in response to the ionic or osmotic effect of salt stress in soybean with cDNA‐AFLP
Authors: UMEZAWA T. , MIZUNO K. , FUJIMURA T. 
Published: March 2003

Abstract‘Ionic effects’ and ‘osmotic effects’ are major components of salt stress in plants. In this study these two parameters were clearly discriminated in soybean (Glycine max (L.) Merr.) using a modified cDNA‐amplified fragment length polymorphism (AFLP) technique. Soybean (cv. Lee) seedlings were exposed to iso‐osmotic treatment consisting of 100 mm NaCl and 12% (w/v) polyethylene glycol 6000 for 24 h. The NaCl treatment fully activated salt tolerance as confirmed by the expression of the inositol‐1‐phosphate synthase gene. Then, gene expression in each sample was examined by cDNA‐AFLP, and 140 differentially expressed cDNA fragments were obtained out of 13 000 amplicons. The percentage of transcripts dependent on ionic (NaCl‐specific) and osmotic effects (common with NaCl and polyethylene glycol) could be evaluated for 44 and 40% of them, respectively. cDNA‐AFLP also revealed the distribution of transcripts in shoots and roots. The ionic effect‐dependent gene expression was more abundant in roots indicating that they showed a greater response to ionic stress than shoots. Several ion transporters, transcription factors and redox enzymes that were specific to the ionic effect may play important roles in the salt tolerance of soybean. The technical advantages of this modified cDNA‐AFLP method are also discussed.
Expression of the early light‐induced protein but not the PsbS protein is influenced by low temperature and depends on the developmental stage of the plant in field‐grown pea cultivars
Authors: NORÉN H. , SVENSSON P. , STEGMARK R. , FUNK C. , ADAMSKA I. , ANDERSSON B. 
Published: March 2003

ABSTRACTPlant cells exposed to photo‐inhibitory conditions respond by accumulation of the early light‐induced proteins (Elips) with a potential photoprotective function. Here we studied the expression of Elip in various pea cultivars grown under agricultural or climate‐chamber conditions. We demonstrated that the expression of Elip in all cultivars was developmentally regulated and its level decreased during flowering and post‐flowering periods. Surprisingly, significant amounts of Elip transcripts, but not proteins, accumulated in senescing leaves already under low light conditions and the exposure to light stress resulted in a 10‐times higher induction of Elip transcripts. Furthermore, the expression pattern of Elip transcript and protein significantly differed under field and growth‐chamber conditions. First, the expression level of Elip was much higher in field‐grown than in chamber‐grown cultivars. Second, substantial amounts of Elip transcripts and protein were detected during the night in field‐grown plants in contrast to chamber‐grown cultivars due to a synergistic effect of light stress occurring during the day and low temperature present during the following night. The expression of the PsbS protein related to Elips and involved in the photoprotection of the photosystem II was relatively constant under all conditions tested.
Induction of different pathogenesis‐related cDNAs in grapevine infected with powdery mildew and treated with ethephon
Authors: Jacobs  , Dry  , Robinson  
Published: March 2003

Uncinula necator, the causal agent of grapevine powdery mildew, was found to elevate the activity of the pathogenesis‐related (PR) proteins, chitinase and β‐1,3‐glucanase in leaves and berries of a number of susceptible grapevine (Vitis vinifera) cultivars. The increase in hydrolytic activity was directly related to the severity of powdery mildew infection on both leaves and berries but no systemic induction was observed in uninfected tissues. A number of cDNA clones encoding various PR proteins, including chitinases (PR‐2), β‐1,3‐glucanases (PR‐3) and thaumatin‐like (TL) proteins (PR‐5), were isolated and their expression in response to powdery mildew infection examined. PR genes encoding extracellular proteins were most strongly induced in infected leaves, including an acidic class III chitinase (VvChi3), a basic class I glucanase (VvGlub) and a thaumatin‐like protein (VvTl2). A basic class I chitinase (VvChi1b) was also detected, but only in severely infected leaves. A similar pattern of PR gene induction was observed in mildew‐infected preveraison berries, with the exception of VvChi1b, which was not detected. Chitinase and β‐1,3‐glucanase enzyme activities were also found to be highly induced in leaves and preveraison berries by ethephon treatment. The pattern of chitinase gene induction by ethephon, however, was markedly different for mildew infection, with no apparent induction of VvChi3 but a marked increase in the transcript level of an acidic class IV chitinase, VvChi4. These results demonstrate that the leaves and preveraison berries of grapevine respond to environmental and stress‐related stimuli by the expression of specific PR genes but that the induction of these genes during pathogen invasion does not afford complete protection of these tissues against Uncinula necator.The following abbreviations have been used: Tris: 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol; EDTA: ethylenediaminetetra‐acetic acid; PVPP: polyvinylpolypyrrolidone. The GenBank accession numbers for VvChi1b and VvGlub are AF053341 and AF053750, respectively.
Effects of calcium on biocontrol activity of yeast antagonists against the postharvest fungal pathogen Rhizopus stolonifer
Authors: Tian S. P. , Fan Q. , Xu Y. , Jiang A. L. 
Published: March 2003

Calcium chloride (2% w/v) significantly inhibited the growth of the pathogen Rhizopus stolonifer, but did not affect the colony‐forming units (CFU) of yeasts Candida guilliermondii and Pichia membranefaciens in potato dextrose broth. The concentration of yeast suspension influenced spore germination and germ tube growth of R. stolonifer in vitro, as well as disease incidence and lesion development in fruits. There were significant negative relationships between the suspension concentrations of the yeasts and the growth as well as infectivity of the pathogen. The addition of calcium resulted in lower spore germination rates and slower growth of germ tubes in vitro, as well as in lower disease incidences and smaller lesion diameters compared with treatments with yeast antagonists alone. When yeast cell suspensions reached a concentration of 5 × 108 CFU mL−1, growth of the pathogen was completely limited in vitro, and no infection was found in peach and nectarine fruits treated with or without calcium.
Detection of Colletotrichum coccodes and Helminthosporium solani in soils by bioassay
Authors: Carnegie S. F. , Choiseul J. W. , Roberts A. M. I. 
Published: March 2003

The sensitivity of a bioassay in detecting soil inoculum of Colletotrichum coccodes and Helminthosporium solani was examined using potato minitubers and microplants. Tests were conducted on soils which were collected from fields in which the interval after a previous potato crop differed, and which were also artificially infested with conidia or microsclerotia. For C. coccodes, determining plant infection based on the occurrence of infected roots after 9–12 weeks was a sensitive method for detecting and quantifying the amount of inoculum in soil. Infestations of less than 0·4 microsclerotia per g soil were detected in artificially infested soils. A semiselective medium, developed for isolating C. gloeosporioides from pepper, detected soil infestations by C. coccodes as low as nine conidia or one microsclerotium per g soil in artificially infested soil. For H. solani, infection on minitubers was a sensitive measure, with soil inoculum of fewer than 10 conidia per g soil being detected. Soil infestation could be quantified by assessing the percentage surface area of minitubers covered by sporulating lesions, which was strongly related to the amount of soil infestation. The results of these bioassay tests were compared with published results for real‐time quantitative PCR assays on the same soils. The two methods were in good agreement in artificially infested soils, but the bioassay appeared to be more sensitive with naturally infested soils.
Immune Regulation in Adjuvant Disease and Other Arthritis Models: Relevance to Pathogenesis of Chronic Arthritis
Authors: Waksman B. H. 
Published: March 2003

Experimental models of arthritis and their human counterparts fall into three distinct classes: (a) responses of T cells to disseminated microbial antigens (Ags) as such; (b) responses of T cells to cartilage autoAgs; and (c) responses of T cells to major histocompatibility complex (HLA‐B27, DRB1) or other membrane components (LFA‐1) expressed on bone marrow‐derived cells. The primary immune response is driven, in naturally occurring disease, by microbial infection, e.g. with streptococci, enteric gram‐negative rods or spirochetes, or is experimentally induced with mycobacterial and other adjuvants. The response to cartilage components, such as collagen type‐II and various proteoglycans, may be driven by cross‐reactive microbial Ags, heat shock proteins (HSPs) in particular, or the adjuvant effect of intense primary joint inflammation, as in rheumatoid arthritis and the spondyloarthropathies.Adjuvant disease appears to be purely T‐cell‐mediated, whereas both T cells and antibody play a role in collagen and many other forms of arthritis. Experimental evidence suggests a pathogenetic role for T‐cell receptor γδ T cells in some lesions. Arthritis may be regulated by microbial and tissue HSPs, when these are administered by a nonimmunizing route or as altered peptide ligands, by anti‐idiotypic responses that block the action of effector T cells, and by competing Ags. Immune regulation involving natural killer (NK), NK T and certain subsets of γδ and αβ T cells, which may affect the occurrence, localization and character of this group of diseases, presents a challenge for further investigation.
Single‐Cell Analysis of Ets‐1 Transcription Factor Expression during Lymphocyte Activation and Apoptosis
Authors: Koskela K. , Lassila O. 
Published: March 2003

AbstractThe Ets‐1 proto‐oncogene is a prototype member of Ets family of transcription factors. It is preferentially expressed in lymphoid cells, where it is essential for the maintenance of the normal pool of resting T and B cells. We have investigated the protein expression of the Ets‐1 transcription factor during the activation and apoptosis of T and B cells by flow cytometry and confocal microscopy. Cells of the thymus, spleen and bursa expressed high levels of Ets‐1 protein, while resting peripheral blood mononuclear cells had lower Ets‐1 expression. Activation and proliferation of T cells induced the upregulation of Ets‐1. αβ‐T cells were found to upregulate Ets‐1 expression more than γδ‐T cells. Increased Ets‐1 protein expression was located predominantly in the perinuclear area. In contrast, during apoptosis, Ets‐1 expression was downregulated. Collectively, our results indicate that Ets‐1 expression can be accurately determined by flow cytometry and confocal microscopy. Ets‐1 expression level and distribution are differentially controlled in resting, activated and apoptotic lymphocytes.
Calcineurin Phosphatase Activity and Immunosuppression. A Review on the Role of Calcineurin Phosphatase Activity and the Immunosuppressive Effect of Cyclosporin A and Tacrolimus
Authors: Jørgensen K. A. , Koefoed‐Nielsen P. B. , Karamperis N. 
Published: March 2003

AbstractThe mode of immunosuppressive action of tacrolimus (FK506) and cyclosporin A has been elucidated. Both drugs bind to proteins in the cytoplasm to form complexes, which in turn inhibit the phosphatase activity of calcineurin, an important limiting step in the activation of T cells. The association between drug uptake (pharmacokinetics) and enzyme inhibition (pharmacodynamics) is under current investigation. Great variations in the correlation between blood drug levels and enzyme inhibition could indicate that monitoring calcineurin phosphatase activity for treatment might be superior to monitoring blood drug levels.
Palaeogeographic and burial controls on anhydrite genesis: the Badenian basin in the Carpathian Foredeep (southern Poland, western Ukraine)
Authors: KASPRZYK ALICJA , ORTÍ FEDERICO 
Published: March 2003

The Badenian (Middle Miocene) Ca‐sulphate deposits of the fore‐Carpathian basin – including the shelf and adjacent salt depocentre – have undergone varying degrees of diagenetic change: they are preserved mainly as primary gypsum in the peripheral part of the platform, whereas toward the centre of the basin, where great subsidence occurred during the Miocene, they have been totally transformed into anhydrite.The facies variation and sequence of Badenian anhydrites reflect different genetic patterns of two members of the Ca‐sulphate formation. In the lower member (restricted to the platform), anhydrite formed mainly by synsedimentary anhydritization (vianodule formation), whereas in the upper member (distributed throughout the platform and depocentre) the various gypsum/anhydrite lithofacies display a continuum of distinctive anhydrite type‐fabrics. These fabrics are based on petrographic features and show from the centre to the margin: (1) syndepositional, interstitial growth of displacive anhydrite; (2) early diagenetic, displacive to replacive (by replacement of former gypsum) anhydrite formation near the depositional surface; (3) early diagenetic, displacive to replacive anhydrite formation during shallow burial; and (4) late‐diagenetic (and only partial) replacement of gypsum at deeper burial. The cross‐shelf lateral relations of anhydrite lithofacies and fabrics suggest that the diagenesis developed as a diachronous process.These fabrics of the upper member reflect both palaeogeographic (linked to different parts of the basin) and burial controls. Anhydrite growth started very early in the basin centre, presumably related to high‐salinity pore fluids; anhydritization prograded updip toward the shelf (landward in a generalized cross‐section through the basin). The intensity of gypsum replacement by anhydrite was progressively attenuated landward by a decrease in the salinity of the pore fluids. In each part of the basin, the anhydrite fabric was also controlled by the texture and degree of lithification of the fine‐grained primary gypsum lithofacies. Recrystallization of these anhydrite fabrics during late diagenesis, linked to deeper burial conditions, is insignificant, allowing reconstruction of the original anhydritization pattern.
Phylogenetic revision ofBonjeaniaIrwin & Lyneborg (Diptera: Therevidae)
Authors: Winterton Shaun L. , Skevington Jeffrey H. , Irwin Michael E. , Yeates David K. 
Published: March 2003

SummaryThe endemic Australian genusBonjeaniaIrwin & Lyneborg is revised. Seven species are described as new:B. angelikaesp.n.,B. clamosissp.n.,B. dynastissp.n.,B. flavofemoralissp.n.,B. irwinaesp.n.,B. orphnesp.n. andB. trilineatasp.n. Three species,B. actuosa(White),B. nitidifrons(Macquart) andB. segnis(White), are redescribed. All species ofBonjeaniawere compared in a cladistic analysis withAgapophytus albobasalisMann and five exemplars of the speciose sister genusParapsilocephalaKröber, and the phylogenetic relationships ofBonjeaniadiscussed. The male genitalic musculature ofB. clamosissp.n. is described and figured, and discussed with respect to previous studies on other Therevidae.
Molecular variation and phylogeny of members of the Minimus Group of Anopheles subgenus Cellia (Diptera: Culicidae)
Authors: Sharpe Rosie G. , Harbach Ralph E. , Butlin Roger K. 
Published: March 2003

SummaryIntra‐ and interspecific molecular variation were investigated in four members of the Minimus Group ofAnophelessubgenusCellia:An. aconitus,An. varuna,An. minimusA andAn. minimusC. DNA sequence divergence between these species at a mitochondrial locus (cytochrome oxidase II) and at three nuclear loci (ITS2 and D3 regions of rDNA and guanylate cyclase) is reported. The data confirm the presence of two cryptic species, A and C, withinAn. minimusand provide evidence for the existence of a third species.Anopheles minimusA and C are estimated to have diverged 0.57–1.5 million years ago. The discrepancy observed using the guanylate cyclase intron, which is the fastest evolving region known in the Gambiae Complex but is relatively slowly evolving in the Minimus Group, is discussed. The long‐term effective population sizes ofAn. minimusA and C are estimated to be in their millions, with that of species A being approximately twice the size of species C. This implies thatAn. minimusC has a much wider distribution than currently recognized, with possible widespread implications for vector control. No evidence was found for population structuring in either species A or C: there was greater variation of mitochondrial haplotypes within than among localities. The phylogenetic relationships of Oriental members of the Myzomyia Series are reconstructed.