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Plant Tissues (plant + tissue)
Kinds of Plant Tissues Terms modified by Plant Tissues Selected AbstractsGlutamine Nitrogen and Ammonium Nitrogen Supplied as a Nitrogen Source Is Not Converted into Nitrate Nitrogen of Plant Tissues of Hydroponically Grown Pak-Choi (Brassica chinensis L.)JOURNAL OF FOOD SCIENCE, Issue 2 2009H.-J. Wang ABSTRACT:, Many vegetables, especially leafy vegetables, accumulate NO,3 -N in their edible portions. High nitrate levels in vegetables constitute a health hazard, such as cancers and blue baby syndrome. The aim of this study was to determine if (1) ammonium nitrogen (NH+4 -N) and glutamine-nitrogen (Gln-N) absorbed by plant roots is converted into nitrate-nitrogen of pak-choi (Brassica chinensis L.) tissues, and (2) if nitrate-nitrogen (NO,3 -N) accumulation and concentration of pak-choi tissues linearly increase with increasing NO,3 -N supply when grown in nutrient solution. In experiment 1, 4 different nitrogen treatments (no nitrogen, NH+4 -N, Gln-N, and NO,3 -N) with equal total N concentrations in treatments with added N were applied under sterile nutrient medium culture conditions. In experiment 2, 5 concentrations of N (from 0 to 48 mM), supplied as NO,3 -N in the nutrient solution, were tested. The results showed that Gln-N and NH+4 -N added to the nutrient media were not converted into nitrate-nitrogen of plant tissues. Also, NO,3 -N accumulation in the pak-choi tissues was the highest when plants were supplied 24 mM NO,3 -N in the media. The NO,3 -N concentration in plant tissues was quadratically correlated to the NO,3 -N concentration supplied in the nutrient solution. [source] Optimizing protein extraction from plant tissues for enhanced proteomics analysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2008Wei Wang Abstract Plant tissues usually contain high levels of proteases and secondary metabolites that severely interfere with protein extraction, separation, and identification. Preparation of high-quality protein samples from plant tissues for proteomic analysis represents a great challenge. This article briefly describes the critical points in protein separation, especially secondary metabolites in plant tissues, and removal strategy. It provides an updated overview of three total protein extraction methods and their applications in proteomic analysis of various recalcitrant tissues. [source] Remarks on the morphology and biology of Cleigastra apicalis (Meigen, 1826) (Diptera, Scathophagidae)ACTA ZOOLOGICA, Issue 4 2006Maria Grochowska Abstract The egg, second- and third-instar larvae and puparium of Cleigastra apicalis are described for the first time. All pre-imaginal stages are found on stems of the common reed affected by flies of the genera Lipara and Platycephala and the butterfly Arenostola phragmitidis. The larvae feed on dead plant and animal tissue and the excreta of other insects that live inside the stems of the common reed. Exceptionally they will scrape living plant tissue. The pupa is the overwintering stage. [source] Top-down and bottom-up diversity cascades in detrital vs. living food websECOLOGY LETTERS, Issue 1 2003Lee A. Dyer Abstract Apex predators and plant resources are both critical for maintaining diversity in biotic communities, but the indirect (,cascading') effects of top-down and bottom-up forces on diversity at different trophic levels are not well resolved in terrestrial systems. Manipulations of predators or resources can cause direct changes of diversity at one trophic level, which in turn can affect diversity at other trophic levels. The indirect diversity effects of resource and consumer variation should be strongest in aquatic systems, moderate in terrestrial systems, and weakest in decomposer food webs. We measured effects of top predators and plant resources on the diversity of endophytic animals in an understorey shrub Piper cenocladum (Piperaceae). Predators and resource availability had significant direct and indirect effects on the diversity of the endophytic animal community, but the effects were not interactive, nor were they consistent between living vs. detrital food webs. The addition of fourth trophic level beetle predators increased diversity of consumers supported by living plant tissue, whereas balanced plant resources (light and nutrients) increased the diversity of primary through tertiary consumers in the detrital resources food web. These results support the hypotheses that top-down and bottom-up diversity cascades occur in terrestrial systems, and that diversity is affected by different factors in living vs. detrital food webs. [source] The ecological and evolutionary significance of frost in the context of climate changeECOLOGY LETTERS, Issue 5 2000D.W. Inouye The effects that below-freezing temperature (frost) can have at times of year when it is unusual are an interesting ecological phenomenon that has received little attention. The physiological consequence of formation of ice crystals in plant tissue is often death of the plants, or at least of sensitive parts that can include flower buds, ovaries, and leaves. The loss of potential for sexual reproduction can have long-lasting effects on the demography of annuals and long-lived perennials, because the short-term negative effects of frosts can result in longer-term benefits through lowered populations of seed predators. The loss of host plants can have dramatic consequences for herbivores, even causing local extinctions, and the loss of just flowers can also affect populations of seed predators and their parasitoids. Frosts can cause local extinctions and influence the geographical distribution of some species. The potential for global climate change to influence the frequency and distribution of frost events is uncertain, but it seems likely that they may become more frequent in some areas and less frequent in others. [source] Electrical penetration graphs of the nymphal stage of Bemisia argentifoliiENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2003Y.X. Jiang Abstract Electrical penetration graph (EPG, DC system) waveforms were recorded from first, second, and third instar Bemisia argentifolii nymphs. Waveforms recorded were similar among the three instars. Four waveforms were recorded and were named C, J, L, and H. Waveform J is new, whereas waveforms C, L, and H of B. argentifolii nymphs were similar to those published previously from greenhouse whitefly nymphs. As in the previous study on greenhouse whitefly nymphs, there was variation in each of waveforms C, L, and H. Waveform C was recorded at an extracellular voltage level, and represents a pathway phase where the stylets penetrate the plant tissue in an intercellular pathway. At the end of waveform C, the voltage dropped to an intracellular level, indicating penetration of a living cell, and the stylet tips then remained in that cell for the rest of the EPG recording, which was sometimes as long as 16 h. Three waveforms (J, L, and H) were recorded during this intracellular phase, beginning with J, a brief (average = 31 s), low amplitude, irregular waveform. J appeared only at the beginning of the intracellular phase, and was followed by either L (five out of eight times) or H (three out of eight times). Waveforms L and H then alternated with one another for the remainder of the intracellular phase. The most conspicuous difference between L and H was the frequency of their voltage fluctuations; L had a lower frequency and H a higher frequency. Usually the shape of waveform L was dominated by voltage peaks in a positive direction, while waveform H was characterized by strong voltage peaks in a negative direction; although some variants of both L and H had distinct voltage peaks in both directions. The electrical origin of both the positive and negative voltage peaks was electromotive force (emf) fluctuation rather than resistance fluctuation. During waveform H, copious amounts of honeydew were produced, indicating that the penetrated cell was a sieve element. We conclude, therefore, that H represents phloem sap ingestion; and because J and L are produced in the same cell as H, then phloem phase is represented by waveforms J, L, and H. The biological correlations for J and L are not yet known. [source] Evaluated fate and effects of atrazine and lambda-cyhalothrin in vegetated and unvegetated microcosms,,ENVIRONMENTAL TOXICOLOGY, Issue 5 2005J. L. Bouldin Abstract Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best-management practices. Our research has shown that the presence of macrophytes and a hydrologic regime aid in the transfer and transformation of pesticides associated with agricultural runoff. This study consisted of application of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to vegetated and unvegetated microcosms in order to measure the fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through concentrations of atrazine and lambda-cyhalothrin in plant tissue as high as 2461.4 and 86.50 ,g/kg, respectively. Toxicity was measured in water from unvegetated microcosms for 28 days and in Chironomus tentans (midge larvae) exposed to sediment collected from 3 h to 56 days in microcosms receiving the pesticide combination. The comparative survival of test organisms in this study suggests that effective mitigation of pesticides from runoff can depend on the macrophyte contact and vegetative attributes associated with ditches. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 487,498, 2005. [source] Uptake and transport of roxarsone and its metabolites in water spinach as affected by phosphate supplyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2010Lixian Yao Abstract Roxarsone (ROX) is widely used as a feed additive in intensive animal production. While an animal is fed with ROX, the As compounds in the manure primarily occur as ROX and its metabolites, including arsenate (As[V]), arsenite (As[III]), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). Animal manure is commonly land applied with phosphorous fertilizers in China. A pot experiment was conducted to investigate the phytoavailability of ROX, As(V), As(III), MMA, and DMA in water spinach (Ipomoea aquatica), with the soil amended with 0, 0.25, 0.50, 1.0, and 2.0,g PO4/kg, respectively, plus 2% (w/w manure/soil) chicken manure (CM) bearing ROX and its metabolites. The results indicate that this species of water spinach cannot accumulate ROX and MMA at detectable levels, but As(V), As(III), and DMA were present in all plant samples. Increased phosphorous decreased the shoot As(V) and As(III) in water spinach but did not affect the root As(V). The shoot DMA and root As(III) and DMA were decreased/increased and then increased/decreased by elevated phosphorous. The total phosphorous content (P) in plant tissue did not correlate with the total As or the three As species in tissues. Arsenate, As(III), and DMA were more easily accumulated in the roots, and phosphate considerably inhibited their upward transport. Dimethylarsinic acid had higher transport efficiency than As(V) and As(III), but As(III) was dominant in tissues. Conclusively, phosphate had multiple effects on the accumulation and transport of ROX metabolites, which depended on their levels. However, proper utilization of phosphate fertilizer can decrease the accumulation of ROX metabolites in water spinach when treated with CM containing ROX and its metabolites. Environ. Toxicol. Chem. 2010;29:947,951. © 2009 SETAC [source] Relationship between soil copper content and copper content of selected crop plants in central ChileENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2001Ricardo Badilla-Ohlbaum Abstract A survey of copper levels in agricultural soils of central Chile revealed two soil clusters,one with a mean copper level of 162 mg/kg and one with a mean copper level of 751 mg/kg of soil. Samples of soils from both soil clusters were characterized on the basis of physicochemical characteristics, and copper extractability was compared by saturation and CaCl2 extraction as well as an acid-leaching procedure (TCLP). We also measured the copper content of various tissues of tomato (Lycopersicon esculentum) and onion (Allium cepa) crops growing on these soils. Other than copper levels, soils from the two clusters were quite similar, with slightly greater levels of molybdenum and cadmium in the high-copper soils. Within each cluster, extracted copper levels and total soil copper levels were not correlated. However, the three extraction procedures solubilized significantly more copper from the high-Cu soils. Mineralogical characterization of the soil particles and depth profiles of soil metal levels in a subsample of sites suggested that highly insoluble copper ore and mining wastes might account for the high copper levels. Neither total nor extractable copper levels allowed statistical prediction of the levels of copper in plant tissue. The edible tissues of both crops had the same mean copper content, regardless of the copper soil level. However, copper contents of stems and leaves were significantly higher for plants growing on the high-Cu soils. These results show that in these soils, high copper levels are associated with very insoluble copper species and thus low bioavailability of copper to crop plants. [source] Composition of organic matter in a subtropical Acrisol as influenced by land use, cropping and N fertilization, assessed by CPMAS 13C NMR spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2005J. Dieckow Summary We know much about the influence of management on stocks of organic matter in subtropical soils, yet little about the influence on the chemical composition. We therefore studied by CPMAS 13C NMR spectroscopy the composition of the above-ground plant tissue, of the organic matter of the whole soil and of silt- and clay-size fractions of the topsoil and subsoil of a subtropical Acrisol under grass and arable crops. Soil samples were collected from three no-till cropping systems (bare soil; oats,maize; pigeon pea + maize), each receiving 0 and 180 kg N ha,1 year,1, in a long-term field experiment. Soil under the original native grass was also sampled. The kind of arable crops and grass affected the composition of the particulate organic matter. There were no differences in the composition of the organic matter in silt- and clay-size fractions, or of the whole soil, among the arable systems. Changes were observed between land use: the soil of the grassland had larger alkyl and smaller aromatic C contents than did the arable soil. The small size fractions contain microbial products, and we think that the compositional difference in silt- and clay-size fractions between grassland and the arable land was induced by changes in the soil's microbial community and therefore in the quality of its biochemical products. The application of N did not affect the composition of the above-ground plant tissue nor of the particulate organic matter and silt-size fractions, but it did increase the alkyl C content in the clay-size fraction. In the subsoil, the silt-size fraction of all treatments contained large contents of aromatic C. Microscopic investigation confirmed that this derived from particles of charred material. The composition of organic matter in this soil is affected by land use, but not by variations in the arable crops grown. [source] Diversity of endophytic bacterial communities in poplar grown under field conditionsFEMS MICROBIOLOGY ECOLOGY, Issue 2 2008Kristina Ulrich Abstract Bacterial endophytes may be important for plant health and other ecologically relevant functions of poplar trees. The composition of endophytic bacteria colonizing the aerial parts of poplar was studied using a multiphasic approach. The terminal restriction fragment length polymorphism analysis of 16S rRNA genes demonstrated the impact of different hybrid poplar clones on the endophytic community structure. Detailed analysis of endophytic bacteria using cultivation methods in combination with cloning of 16S rRNA genes amplified from plant tissue revealed a high phylogenetic diversity of endophytic bacteria with a total of 53 taxa at the genus level that included Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. The community structure displayed clear differences in terms of the presence and relative proportions of bacterial taxa between the four poplar clones studied. The results showed that the genetic background of the hybrid poplar clones corresponded well with the endophytic community structure. Out of the 513 isolates and 209 clones identified, Actinobacteria, in particular the family Microbacteriaceae, made up the largest fraction of the isolates, whereas the clone library was dominated by Alpha - and Betaproteobacteria. The most abundant genera among the isolates were Pseudomonas and Curtobacterium, while Sphingomonas prevailed among the clones. [source] Sclerotinia sclerotiorum: When "to be or not to be" a pathogen?FEMS MICROBIOLOGY LETTERS, Issue 2 2005Dwayne D. Hegedus Abstract Sclerotinia sclerotiorum is unusual among necrotrophic pathogens in its requirement for senescent tissues to establish an infection and to complete the life cycle. A model for the infection process has emerged whereby the pathogenic phase is bounded by saprophytic phases; the distinction being that the dead tissues in the latter are generated by the actions of the pathogen. Initial colonization of dead tissue provides nutrients for pathogen establishment and resources to infect healthy plant tissue. The early pathogenicity stage involves production of oxalic acid and the expression of cell wall degrading enzymes, such as specific isoforms of polygalacturonase (SSPG1) and protease (ASPS), at the expanding edge of the lesion. Such activities release small molecules (oligo-galacturonides and peptides) that serve to induce the expression of a second wave of degradative enzymes that collectively bring about the total dissolution of the plant tissue. Oxalic acid and other metabolites and enzymes suppress host defences during the pathogenic phase, while other components initiate host cell death responses leading to the formation of necrotic tissue. The pathogenic phase is followed by a second saprophytic phase, the transition to which is effected by declining cAMP levels as glucose becomes available and further hydrolytic enzyme synthesis is repressed. Low cAMP levels and an acidic environment generated by the secretion of oxalic acid promote sclerotial development and completion of the life cycle. This review brings together histological, biochemical and molecular information gathered over the past several decades to develop this tri-phasic model for infection. In several instances, studies with Botrytis species are drawn upon for supplemental and supportive evidence for this model. In this process, we attempt to outline how the interplay between glucose levels, cAMP and ambient pH serves to coordinate the transition between these phases and dictate the biochemical and developmental events that define them. [source] Dothistroma (red-band) needle blight of pines and the dothistromin toxin: a reviewFOREST PATHOLOGY, Issue 3 2004R. E. Bradshaw Summary Dothistroma (red-band) needle blight has been a problem in plantations of exotic pines in the southern hemisphere for many decades. The prevalence of this disease is currently increasing in the northern hemisphere and is now affecting trees in their native ranges. The fungal pathogen Mycosphaerella pini with its anamorph Dothistroma pini, which is responsible for the disease, produces a toxin, dothistromin, that is closely related to the potent carcinogen, aflatoxin. Understandably this has provoked concern about possible effects on the health of forestry workers. This review gives a broad coverage of literature on both disease and toxin. The fungus has a complicated taxonomy with many synonyms and in most countries only the anamorph is found. It is a necrotrophic pathogen that kills needle tissue and completes its life cycle in the lesion thus formed. Dispersal of the disease is normally by rain splash of conidiospores but there is evidence that long range dispersal has occurred by transport of contaminated plant tissue and by wind/cloud dispersal of spores in air currents. The severity of disease is affected by humidity, temperature and light. There is variation in susceptibility of different Pinus species and some achieve increased resistance with age. The current method of control in southern hemisphere plantation forests is through spraying with copper fungicides and, with P. radiata, increased disease resistance has been achieved through a breeding programme. The dothistromin toxin is a difuroanthraquinone and is similar in structure to the aflatoxin precursor versicolorin B. Part of a gene cluster encoding dothistromin biosynthetic genes has been cloned and this has confirmed parallels between the dothistromin and aflatoxin biosynthetic pathways. Dothistromin produces damaging oxygen radicals by reductive oxygen activation rather than by photosensitization, but is also thought to exert its toxic effects on specific cellular targets. Studies have shown that dothistromin is a weak mutagen and clastogen and is therefore a potential carcinogen. Although the risks to forest workers are considered very low it is prudent to avoid unnecessary exposure during periods when dothistromin levels are likely to be at their peak. Résumé La maladie des bandes rouges causée par Dothistroma est un problème dans les plantations de pins exotiques de l'hémisphère sud depuis de nombreuses années. La prévalence de cette maladie est en augmentation dans l'hémisphère nord et affecte maintenant les pins dans leurs régions d'origine. Le champignon pathogène Dothistroma pini, responsable de la maladie, produit une toxine, la dothistromine, proche de l'aflatoxine qui est un puissant carcinogène. Ceci pose donc la question des effets possibles sur la santé des travailleurs forestiers. Cette revue repose sur une large couverture de la littérature concernant aussi bien la maladie que la toxine. Le champignon a une taxonomie complexe avec de nombreux synonymes, et seul l'anamorphe se rencontre dans de nombreux pays. C'est un champignon nécrotrophe qui tue les tissus de l'aiguille et réalise son cycle biologique dans la lésion ainsi formée. La dissémination de la maladie s'effectue principalement par éclaboussures de pluie contenant les conidies mais une dissémination à longue distance a été mise en évidence par transport de matériel contaminé ou par dissémination des spores par le vent ou les nuages dans les courants aériens. La sévérité de la maladie est affectée par l'humidité, la température et la lumière. Il existe des différences de sensibilité entre espèces de Pinus, et certaines présentent une résistance accrue avec l'âge. La méthode actuelle de lutte dans les forêts de plantations de l'hémisphère sud consiste à pulvériser des fongicides à base de cuivre ; dans le cas de Pinus radiata, une augmentation de la résistance a été obtenue grâce à un programme d'amélioration génétique. La toxine dothistromine est une difuroanthraquinone, similaire en structure à la versicolorine B, précurseur de l'aflatoxine. Une partie d'une batterie de gènes comprenant des gènes de biosynthèse de la dothistromine a été clonée, confirmant les analogies entre les voies de biosynthèse de la dothistromine et de l'aflatoxine. La dothistromine produit des radicaux oxygène nocifs par activation de la réduction de l'oxygène plutôt que par photosensibilisation, mais ses effets toxiques s'exercent aussi probablement sur des sites cellulaires spécifiques. Des études montrent que la dothistromine est un mutagène et clastogène faible, et donc potentiellement carcinogène. Bien que les risques pour les ouvriers forestiers soient considérés comme très faibles, il est prudent d'éviter dans la mesure du possible de s'exposer dans les périodes où les niveaux de dothistromine sont supposés élevés. Zusammenfassung Die Dothistroma -Nadelbräune ist in der Südhemisphäre in Plantagen mit exotischen Kiefernarten seit vielen Jahren ein Problem. In der Nordhemisphäre nimmt die Bedeutung dieser Krankheit derzeit zu und sie befällt nun Bäume auch in ihren natürlichen Verbreitungsgebieten. Der Erreger ist der Ascomycet Mycosphaerella pini (Anamorphe: Dothistroma pini). Der Pilz bildet das Toxin Dothistromin, das eng mit dem hochtoxischen Karzinogen Aflatoxin verwandt ist. Daraus ergab sich die Frage nach möglichen Nebenwirkungen dieser Baumkrankheit auf die Gesundheit von Waldarbeitern. Dieser Review fasst die Information über die Krankheit und das Toxin zusammen. Der Pilz hat eine komplizierte Taxonomie mit vielen Synonymen und in den meisten Ländern wurde nur die Anamorphe nachgewiesen. Er ist ein nekrotrophes Pathogen, das Blattgewebe abtötet, und in den so gebildeten Läsionen seinen Lebenszyklus abschliesst. Der normale Ausbreitungsweg der Krankheit erfolgt über Konidiosporen mit Regentropfen, aber es gibt auch Hinweise auf einen Ferntransport mit infiziertem Pflanzenmaterial und über die Verbreitung von Sporen mit dem Wind bzw. Wolken in Luftströmungen. Die Krankheitsintensität wird durch Luftfeuchte, Temperatur und Licht beeinflusst. Es gibt Unterschiede in der Anfälligkeit zwischen verschiedenen Kiefernarten und manche davon werden mit zunehmendem Alter resistenter. Derzeit werden in Plantagen der südlichen Hemisphäre Kupferfungizide zur Kontrolle dieser Krankheit eingesetzt und für Pinus radiata wurde in Züchtungsprogrammen eine erhöhte Resistenz erreicht. Das Toxin Dothistromin ist ein Difuroanthrachinon und ähnelt in seiner Struktur dem Aflatoxin-Präkursor Versicolorin B. Ein Teil des Genclusters, das die Dothistromin-Biosynthese codiert, wurde geklont, und es wurden dabei Parallelen zwischen dem Dothistromin- und dem Aflatoxin-Biosyntheseweg bestätigt. Dothistromin bildet schädliche Sauerstoffradikale (wahrscheinlich eher durch reduktive Sauerstoffaktivierung als durch Photosensibilisierung), es dürfte aber auch auf spezifische Zellkomponenten toxisch wirken. Dothistromin zeigt schwache mutagene und chromosomenschädigende Wirkungen und ist deshalb ein potentielles Karzinogen. Obwohl das Risiko für Waldarbeiter als gering eingeschätzt wird, sollte man in Perioden, in denen der Dothistromingehalt hoch sein dürfte, eine unnötige Exposition vermeiden. [source] Cell wall hemicelluloses as mobile carbon stores in non-reproductive plant tissuesFUNCTIONAL ECOLOGY, Issue 5 2007G. HOCH Summary 1As essential compounds of plant cell walls, hemicelluloses account for about a quarter of all plant biomass worldwide. 2In seed cotyledons and endosperm of species from several plant families, hemicelluloses are used as mobile carbon reserves. Whether cell wall hemicelluloses of non-reproductive plant tissue are multifunctional molecules, which can also serve as carbon sources during periods of enhanced carbon demand, is still equivocal. 3This review summarizes the current understanding of a possible reserve function of hemicelluloses. Although several descriptive and experimental studies suggested at least partial mobility of cell wall polysaccharides in mature, non-reproductive plant tissues, there is still a need for a broad-scale, ecophysiological exploration of the actual nature of hemicelluloses beyond their structural function. 4The chemical heterogeneity of hemicelluloses may be the major problem for precise quantitative analyses on a large, comparative scale. 5Because of the abundant distribution of hemicelluloses in plants, the existence of a significant mobile carbohydrate pool in cell walls of non-reproductive organs would shed rather new light on plant carbon relations in a source-sink context. 6Consequently, a reserve function of hemicelluloses questions the conventional division of cell compounds into structural (i.e. immobile) and non-structural (i.e. mobile) compounds. [source] Soil animals influence microbial abundance, but not plant,microbial competition for soil organic nitrogenFUNCTIONAL ECOLOGY, Issue 5 2004L. COLE Summary 1In a microcosm experiment we examined the effects of individual species of microarthropods, and variations in microarthropod diversity of up to eight species, on soil microbial properties and the short-term partitioning of a dual-labelled organic nitrogen source (glycine-2- 13C- 15N) between a grassland plant, Agrostis capillaris, and the soil microbial biomass, to determine how soil fauna and their diversity influence plant,microbial competition for organic N. 2We hypothesized that variations in the diversity of animals would influence the partitioning of 15N inputs between plants and the microbial biomass, due to the effect of animal grazing on the microbial biomass, and hence its ability to sequester N. 3Certain individual species of Collembola influenced the microbial community of the soil. Folsomia quadrioculata reduced microbial biomass, whereas Mesaphorura macrochaeta enhanced arbuscular mycorrhizal (AM) colonization of A. capillaris roots. Effects of increasing species richness of microarthropods on microbial biomass and AM colonization were detected, but these effects could be interpreted in relation to the presence or absence of individual species. 4Microbial uptake of added 15N was not affected by the presence of any of the individual species of animal in the monoculture treatments. Similarly, increasing diversity of microarthropods had no detectable effect on microbial 15N. 5Root and shoot uptake of 15N was also largely unaffected by both single species and variations in diversity of microarthropods. However, one collembolan species, Ceratophysella denticulata, reduced root 15N capture when present in monoculture. We did not detect 13C in plant tissue under any experimental treatments, indicating that all N was taken up by plants after mineralization. 6Our data suggest that, while single species and variations in diversity of microarthropods influence microbial abundance in soil, there is no effect on microbial or plant uptake of N. Overall, these data provide little support for the notion that microbial-feeding soil animals are regulators of microbial,plant competition for N. [source] Thermogenesis and respiration of inflorescences of the dead horse arum Helicodiceros muscivorus, a pseudo-thermoregulatory aroid associated with fly pollinationFUNCTIONAL ECOLOGY, Issue 6 2003R. S. Seymour Summary 1In central Corsica, Helicodiceros muscivorus (Schott ex. K. Koch) produces a protogynous inflorescence that resembles the anal area of a dead mammal and produces a foetid scent during the few hours after sunrise. Flies enter the floral chamber, pollinate the female florets and become trapped until the next morning, when pollen is shed from the male florets and the flies are released. 2The exposed appendix exhibits a strong, unimodal episode of thermogenesis associated with scent production, reaching a maximum of 30 °C at 15 °C ambient temperature. The male florets in the floral chamber are highly thermogenic throughout the second night and generally maintain stable floret temperatures of about 24 °C at ambient temperatures down to 13 °C. 3Maximum respiration rates of the appendix (0·45 µmol CO2 s,1 g,1) and the male florets (0·82 µmol s,1 g,1) may be the highest recorded for plant tissue. 4Thermogenesis of the appendix does not depend on ambient temperature, but that of the male florets increases with decreasing ambient temperature in most cases. However, the pattern of heat production by the males appears related more to time than to ambient temperature, hence the term ,pseudo-thermoregulation'. 5The behaviour and thoracic temperatures of flies emerging from captivity suggests that male floral warming does not enhance their activity. [source] Developmental impact on trans -acting dosage effects in maize aneuploidsGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 2 2001Jennifer L. Cooper Abstract Summary: The reduction in vigor or viability caused by aneuploidy may be the result of trans -acting dosage effects that reduce gene expression. To investigate the molecular and developmental parameters of aneuploid syndromes, the expression of sucrose synthase1 (sus1) and shrunken1 (sh1) was studied in 2-week-old plants. Expression of sus1 and sh1 was first investigated in euploids, where it was found that both transcripts varied in a diurnal fashion. Chromosome arm number can be varied in a series from one to three doses in maize. In the 14 aneuploid dosage series examined, most caused changes in sus1 and sh1 RNA levels that were both gene and tissue specific. Results were compared to previous data from embryo and endosperm tissue. More dosage effects were detected and the magnitude of RNA level modulation was greater in 2-week-old plant tissue. These findings suggest that the molecular consequences of aneuploidy might become more severe as development progresses. genesis 31:64,71, 2001. © 2001 Wiley-Liss, Inc. [source] Poor host plant quality causes omnivore to consume predator eggsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2003Arne Janssen Summary 1Omnivorous arthropods are known to change their diet when host plant quality is low. Consequently, it has been suggested that decreased plant quality has a twofold negative effect on herbivore populations: (1) a decrease in growth rate of herbivores; (2) omnivores include more herbivores in their diet. We hypothesized that decreased host plant quality may also cause omnivores to feed on predators, including their own enemies. 2We tested this hypothesis, using the omnivorous western flower thrips. This species is known to feed on many plant species, but also on the eggs of another herbivore, the two-spotted spider mite. Previous research has shown that a decrease in plant quality leads to increased feeding on spider mite eggs by western flower thrips. Western flower thrips also kill the eggs of various predatory mites, including those of the specialist predator of spider mites and those of a predatory mite that attacks western flower thrips itself. 3In this paper we investigate whether thrips larvae kill predator eggs to feed on them and whether this predation depends on host plant quality. 4Larval survival as well as developmental rate increased when plant tissue of low quality (sweet pepper) was supplemented with eggs of two predatory mite species or when it was supplemented with pollen, a high-quality food type. 5Supplementing high quality leaf tissue (cucumber) with predator eggs did not lead to increased survival and developmental rate. Thrips larvae fed significantly less on predatory mite eggs when pollen was available. 6Thus, thrips larvae indeed feed on predator eggs, including those of their predator, and they feed more on predator eggs when host plants are of low quality. [source] Effect of an arbuscular mycorrhizal fungus, Glomus mosseae, and a rock-phosphate-solubilizing fungus, Penicillium thomii, on Mentha piperita growth in a soilless mediumJOURNAL OF BASIC MICROBIOLOGY, Issue 3 2005Marta Cabello Dr. Rock phosphate effect on English mint (Mentha piperitaL.) grown on steamed perlite:vermiculite (1:1, v:v) substrate, with and without rock phosphate, was evaluated in greenhouse experiments. Five treatments were carried out by inoculation with an arbuscular mycorrhizal fungus Glomus mosseae and a phosphorus solubilizing microorganism Penicillium thomii. Plant aerial biomass, phosphorus concentration in plant tissue, and P available in the substrate, were evaluated upon two harvests. After the first harvest, plant aerial biomass did not show significant differences between treatments using rock phosphate as fertilizer, although P content in plants inoculated with P. thomii was higher. The second harvest revealed a higher biomass and plant tissue P content in treatments inoculated with G. mosseae. P. thomii increased P available in the substrate, whereas in the absence of G. mosseae, it did not enhance plant tissue P content. Mycorrhizal colonization was not affected by P. thomii. Microbial inoculation effect on English mint growth was also evaluated. The microbial effect was positive in all treatments when compared with the control without rock phosphate. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of past changes in inter-annual temperature variability on tree distribution limitsJOURNAL OF BIOGEOGRAPHY, Issue 7 2010Thomas Giesecke Abstract Aim, The northern limits of temperate broadleaved species in Fennoscanndia are controlled by their requirements for summer warmth for successful regeneration and growth as well as by the detrimental effects of winter cold on plant tissue. However, occurrences of meteorological conditions with detrimental effects on individual species are rare events rather than a reflection of average conditions. We explore the effect of changes in inter-annual temperature variability on the abundances of the tree species Tilia cordata, Quercus robur and Ulmus glabra near their distribution limits using a process-based model of ecosystem dynamics. Location, A site in central Sweden and a site in southern Finland were used as examples for the ecotone between boreal and temperate forests in Fennoscandia. The Finnish site was selected because of the availability of varve-thickness data. Methods, The dynamic vegetation model LPJ-GUESS was run with four scenarios of inter-annual temperature forcing for the last 10,000 years. In one scenario the variability in the thickness of summer and winter varves from the annually laminated lake in Finland was used as a proxy for past inter-annual temperature variability. Two scenarios were devised to explore systematically the effect of stepwise changes in the variance and shape parameter of a probability distribution. All variability scenarios were run both with and without the long-term trend in Holocene temperature change predicted by an atmospheric general circulation model. Results, Directional changes in inter-annual temperature variability have significant effects on simulated tree distribution limits through time. Variations in inter-annual temperature variability alone are shown to alter vegetation composition by magnitudes similar to the magnitude of changes driven by variation in mean temperatures. Main conclusions, The varve data indicate that inter-annual climate variability has changed in the past. The model results show that past changes in species abundance can be explained by changes in the inter-annual variability of climate parameters as well as by mean climate. Because inter-annual climatic variability is predicted to change in the future, this component of climate change should be taken into account both when making projections of future plant distributions and when interpreting vegetation history. [source] Plant amino acid uptake, soluble N turnover and microbial N capture in soils of a grazed Arctic salt marshJOURNAL OF ECOLOGY, Issue 4 2003Hugh A. L. Henry Summary 1The uptake of free amino acids by the grass Puccinellia phryganodes was investigated in soils of an Arctic coastal salt marsh, where low temperatures and high salinity limit inorganic nitrogen (N) availability, and the availability of soluble organic N relative to inorganic N is often high. 2Following the injection of 13C15N-amino acid, 15N-ammonium and 15N-nitrate tracers into soils, rates of soluble nitrogen turnover and the incorporation of 13C and 15N into plant roots and shoots were assessed. Chloroform fumigation-extraction was used to estimate the partitioning of labelled substrates into microbial biomass. 3Free amino acids turned over rapidly in the soil, with half-lives ranging from 8.2 to 22.8 h for glycine and 8.9 to 25.2 h for leucine, compared with 5.6 to 14.7 h and 5.6 to 15.6 h for ammonium and nitrate, respectively. 15N from both organic and inorganic substrates was incorporated rapidly into plant tissue and the ratio of 13C/15N incorporation into plant tissue indicated that at least 5,11% of 13C15N-glycine was absorbed intact. 4Microbial C and N per unit soil volume were 1.7 and 5.4 times higher, respectively, than corresponding values for plant C and N. Plant incorporation of 15N tracer was 56%, 83% and 68% of the comparable incorporation by soil microorganisms of glycine, ammonium and nitrate ions, respectively. 5These results indicate that P. phryganodes can absorb amino acids intact from the soil despite competition from soil microorganisms, and that free amino acids may contribute substantially to N uptake in this important forage grass utilized by lesser snow geese in the coastal marsh. [source] Influence of Exposure to Light on the Sensorial Quality of Minimally Processed CauliflowerJOURNAL OF FOOD SCIENCE, Issue 1 2007Susana Sanz Cervera ABSTRACT:, The impact of lighting on minimally processed cauliflower packaged in 4 different film types (PVC and 3 P-Plus) has been measured and quantified. The effect on the sensorial quality of storage at 4 °C in darkness and partial or continuous lighting was evaluated. The gas concentrations in the packages and the weight losses were also determined. Atmosphere composition inside the packages depended on both the permeability of the film used for the packaging and exposure to light. Samples stored with lighting maintained the gaseous exchange between plant tissue and the atmosphere inside the packages for longer periods than in samples kept in darkness. This prompted a greater loss of water vapor as well as the development of atmospheres with low levels of O2 and high levels of CO2 in the samples packed with less permeable films. The most important aspect in sensory evaluation was color. In instrumental color evaluation, coordinates h* and L* were the main means for estimating color evolution. The presence of light accelerated browning in the cut zones. The development of abnormal coloring in these areas marked the end of shelf life for minimally processed cauliflower. Among the sensory attributes studied, color was the most affected by exposure to light. Samples packed in P-Plus 120 film displayed the lowest level of color deterioration in the cut zones. However, under lit conditions, the low permeability of this film caused atmospheres with very low O2 contents and high CO2 contents. These atmospheres produced a loss of texture and the development of off-odors. [source] THE USE OF NEAR INFRARED REFLECTANCE SPECTROMETRY FOR CHARACTERIZATION OF BROWN ALGAL TISSUE,JOURNAL OF PHYCOLOGY, Issue 5 2010Kyra B. Hay Measuring qualitative traits of plant tissue is important to understand how plants respond to environmental change and biotic interactions. Near infrared reflectance spectrometry (NIRS) is a cost-, time-, and sample-effective method of measuring chemical components in organic samples commonly used in the agricultural and pharmaceutical industries. To assess the applicability of NIRS to measure the ecologically important tissue traits of carbon, nitrogen, and phlorotannins (secondary metabolites) in brown algae, we developed NIRS calibration models for these constituents in dried Sargassum flavicans (F. K. Mertens) C. Agardh tissue. We then tested if the developed NIRS models could detect changes in the tissue composition of S. flavicans induced by experimental manipulation of temperature and nutrient availability. To develop the NIRS models, we used partial least squares regression to determine the statistical relationship between trait values determined in laboratory assays and the NIRS spectral data of S. flavicans calibration samples. Models with high predictive power were developed for all three constituents that successfully detected changes in carbon, nitrogen, and phlorotannin content in the experimentally manipulated S. flavicans tissue. Phlorotannin content in S. flavicans was inversely related to nitrogen availability, and nitrogen, temperature, and tissue age interacted to significantly affect phlorotannin content, demonstrating the importance of studies that investigate these three variables simultaneously. Given the speed of analysis, accuracy, small tissue requirements, and ability to measure multiple traits simultaneously without consuming the sample tissue, NIRS is a valuable alternative to traditional methods for determining algal tissue traits, especially in studies where tissue is limited. [source] Development of a Sensitive Serological Method for Specific Detection of Latent Infection of Macrophomina phaseolina in CowpeaJOURNAL OF PHYTOPATHOLOGY, Issue 1 2009Leonard Afouda Abstract A double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was developed for the specific detection and quantification of Macrophomina phaseolina in plant tissue. Both polyclonal antisera produced against immunogens from mycelium and culture filtrate of M. phaseolina detected the fungus in mycelial and plant extracts, although the antibodies raised against mycelium were more sensitive. No cross-reaction occurred with Rhizopus stolonifer, Pythium ultimum, Mucor hiemalis, Fusarium oxysporum, Septoria nodorum, Rhizoctonia solani, Sclerotinia sclerotiorum, Phytophthora infestans and Aspergillus niger. In enzyme assays, activity of the endo-acting hydrolytic enzymes 1,3-,-glucanase and, less, cellulase, but not xylanase was detected in infected plants. DAS-ELISA was more sensitive than the 1,3-,-glucanase assay. In polyacrylamide gel electrophoresis (PAGE) up to 18 protein bands were observed, with four bands occurring in the 12 tested isolates deriving from various geographical origin in Niger and Nigeria. The enzyme assays and protein patterns were considered not suitable for specific M. phaseolina detection. Macrophomina phaseolina was essentially located in the roots and hypocotyls, and less in epicotyls and leaves of infected plants. The antibodies were also useful to detect latent infection and the infection of cowpea seeds. [source] Copper, zinc, and cadmium accumulation in two prairie soils and crops as influenced by repeated applications of manure,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2007Sarah L. Lipoth Abstract A study was conducted to determine the effect of repeated (5,7 y) annual application of liquid swine or solid cattle manure on the plant availability of copper (Cu), zinc (Zn), and cadmium (Cd) at two field sites in the W-central and E-central agricultural regions of Saskatchewan, Canada. Soil samples, plant-straw and grain samples from the 2003 growing season were collected and analyzed for total Cu, Zn, and Cd concentrations using nitric acid microwave digestion followed by atomic-absorption spectroscopy. An ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA) extraction was performed on the soil samples as a measure of the plant-available fraction. Crop plants that were tested included wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). The results of this study indicated that long-term repeated applications of manure fertilizer sometimes resulted in increased plant availability of Cu, Zn, and Cd, as reflected in increased concentrations of the plant-available metal observed both in the soil and plant tissue. In the case of Cu and Zn, these increases were related to the rate of application, as the manure is a source of Cu and Zn. Changes in soil conditions from repeated manure application, including a decrease in pH and stimulated plant-root growth can explain the effect that both manure and urea-fertilizer application had on increasing the Cd concentration in the plant. Overall, there does not appear to be any concern about soil metal loading and plant accumulation in these soils after 5,7 y of manure application, as soil and plant concentrations were well below the allowable limits. [source] MEASUREMENT OF FIRMNESS OF FRESH-CUT SLICED TOMATO USING PUNCTURE TESTS , STUDIES ON SAMPLE SIZE, PROBE SIZE AND DIRECTION OF PUNCTUREJOURNAL OF TEXTURE STUDIES, Issue 5 2007MILZA M. LANA ABSTRACT In order to investigate the firmness of tomato slices, two experiments were performed. In the first one, Monte Carlo simulation was used to study the variation in firmness within and between slices. Adding more slices and more measurements per slice reduced the SD, but in general, the efficiency of adding more slices was higher. In the second experiment, the firmness of tomato slices was measured by puncture test during storage, using one of three flat-tipped cylindrical probes (3.5-, 2.5- and 1.5-mm diameter) in two directions, along or perpendicular to the main axis of the fruit. Changes in firmness were studied by nonlinear regression analysis. The same model could be applied to all combinations of probe size and direction with the same correction for shear and compression. It suggests that shear and compression forces decay with storage time according to the same mechanism, irrespective of the measurement direction. PRACTICAL APPLICATIONS Methodologies for both firmness evaluation and data analysis were presented. Monte Carlo simulation was used to optimize the number of samples for firmness assays. After calculating the experimental SD from preliminary experimental results, simulations were performed with different numbers of replicates and measurements per replicate, to find an optimal experimental design where the SD is minimized. Using nonlinear regression, the effects on firmness of probe size, puncture direction in relation to the plant tissue and storage time can be analyzed simultaneously. The incorporation of a correction factor to account for differences in firmness due to probe size was proposed. The relative influence of shear (s) and compression force (c) on the observed force is estimated. Results of interest for the industry were presented, confirming previous findings that the firmness of ripened tomato slices measured by puncture analysis does not change significantly during short-term storage at low temperature. [source] Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water cultureJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2010Wim Voogt Abstract BACKGROUND: Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. RESULTS: In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 µg iodine L,1, applied as iodate (IO3,) or iodide (I,), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I, than with IO3,. Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 µg iodine kg,1 total leaf fresh weight. CONCLUSION: Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I, and IO3,. I, was more effective than IO3,. Fifty grams of iodine-biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults. Copyright © 2010 Society of Chemical Industry [source] The effect of sowing date and growth stage on the essential oil composition of three types of parsley (Petroselinum crispum)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2004SA Petropoulos Abstract Essential oils obtained by simultaneous distillation,extraction (SDE) from leaves, petioles and roots of three types of parsley (turnip-rooted, plain leaf and curly leaf type), sown on three different dates, were analysed by GC-MS (gas chromatography,mass spectrometry) analysis. Parsley plants were found to produce mainly ,-phellandrene, 1,3,8- p -menthatriene, ,-,p -dimethylstyrene, myristicin, ,-myrcene and apiole. In some cases ,- and ,-pinene were also found, whereas ,-elemene was detected, especially in the curly leaf type. The growth stage, plant tissue and date of sowing, as well as the climate conditions, all had a significant effect on the essential oil composition by altering the ratio of the above substances. Copyright © 2004 Society of Chemical Industry [source] Fate of Escherichia coli O157:H7 and Salmonella from contaminated manure slurry applied to soil surrounding tall fescueLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2009M.L. Looper Abstract Aim:, To investigate the potential transfer of Escherichia coli O157:H7 and Salmonella from contaminated manure slurry into the tissue of tall fescue plants. Methods and Results:, Tall fescue plants (n = 50) were fertilized with a manure slurry inoculated with E. coli O157:H7 and Salmonella. Soil was collected and tall fescue plants (n = 10 per day) harvested on day 1, 2, 4, 8, and 14 after manure slurry fertilization. Soil samples were positive for E. coli O157:H7 on all days and on day 1, 2, 8, and 14 for Salmonella. None of the plant tissue samples were positive for E. coli O157:H7 on day 1 or 2; however, 20%, 30% and 40% of plant tissue samples were positive for E. coli O157:H7 on day 4, 8, and 14, respectively. Conclusions:, It may be possible that E. coli O157:H7 can become transmitted and internalized into tall fescue plant tissue within 4 days after exposure to an E. coli O157:H7-contaminated manure slurry. Salmonella did not appear to be transferred to tall fescue plant tissue. Significance and Impact of the Study:, Faeces contaminated with E. coli O157:11H7 may be one means by which grazing ruminants spread bacterial pathogens to additional animals. [source] Interaction of live and dead Escherichia coli O157:H7 and fluorescent microspheres with lettuce tissue suggests bacterial processes do not mediate adherenceLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2006E.B. Solomon Abstract Aims:, The goal of this study was to determine whether any specific bacterial processes (biochemical or genetic) or cell surface moieties were required for the interaction between Escherichia coli O157:H7 and lettuce plant tissue. Methods and Results:,Escherichia coli O157:H7 and FluospheresTM (fluorescent polystyrene microspheres) were used in experiments to investigate interactions with lettuce. FluospheresTM were used as they are a nonbiological material, of similar size and shape to a bacterial cell, but lack bacterial cell surface moieties and the ability to respond genetically. Live and glutaraldehyde-killed E. coli O157:H7 attached at levels of c. 5·8 log10 cells per cm2 following immersion of lettuce pieces into a suspension containing c. 8 log10 CFU ml,1. In a separate experiment, numbers of bacteria or FluospheresTM associated with lettuce decreased by c. 1·5 log cm,2 following a 1-min wash. Exposure times of 1 min, 1 h, or 6 h had little effect on the level of attachment for FluospheresTM, and live or killed cells of E. coli O157:H7 to lettuce tissue. Significance:, These results indicate that bacterial processes and cell surface moieties are not required for the initial interaction of E. coli O157:H7 to lettuce plant tissue. [source] | ||||||||||||||||||||||||||||||||||||||||