1,720,984 research outputs found
Cerato-platanin from C. fimbriata f. sp. platani is an host resistance inducing protein and is produced by other strains of C. fimbriata and by some other species of the genus Ceratocystis
No full textCerato-platanin (CP) is a 120 amino acids protein [1, 5], produced by the Ascomycete Ceratocystis fimbriata f. sp. platani (Cfp), the causal agent of the plane canker stain. The species C. fimbriata attacks various other plants of considerable importance in agriculture, forestry and for their ornamental value; as a rule, one fungal strain isolated from one host is not virulent on the other plant species, and conversely, susceptible hosts are resistant to C. fimbriata strains if they come from hosts other than themselves. This means that the forma specialis platani of the species C. fimbriata attacks only the trees belonging to the genus Platanus, but not the hosts of the all other formae speciales of the fungus. CP is located in the cell walls of Cfp ascospores, hyphae and conidia, and is early secreted when Cfp is grown in liquid culture [2, 3]. CP elicits phytoalexin synthesis and/or cell necrosis in host and in non-host tissues; in plane leaves the main effects of CP are to cause a great increase in primary starch and a certain degree of intercellular and intracellular disorganization of the spongy parenchyma cells and plasmolysis processes; in addition, an increase of intracellular phenolic compounds has been observed in the palisade cells [3, 4]. In the present work we report that the minimum CP concentration able to induce the decrease of the 50% Cfp growth on plane leaves is of about 5 x 10-5 M; the maximum inducing effect has been obtained 24-48 hours post treatment. At this time, numerous defense-related genes are over-expressed, as it has been shown by Suppressive Subtractive Hybridisation. Moreover, results so far obtained by immunotechnical experiments on a total of 17 strains (9 of C. fimbriata, as well as 1 isolate each of C. moniliforme, C. allantospora, C. fagacearum, C. laricicola, C. ambrosia, Microascus cirrosus, Ophiostoma ulmi and O. novo-ulmi) indicate that a CP-homologous protein occurs in all strains of C. fimbriata and in some other species of Ceratocystis. For some strains of C. fimbriata the coding sequences of the cp-hortologous genes have been obtained, and then the sequences of the deduced proteins. BIBLIOGRAFIA 1. Pazzagli L, Cappugi G, Manao G, Camici G, Santini A and Scala A, 1999. Purification of cerato-platanin, a new phytotoxic protein from Ceratocystis fimbriata f.sp. platani. Journal of Biological Chemistry 274: 24959-24964. 2. Boddi S, Comparini C, Calamassi R, Pazzagli L, Cappugi G and Scala A, 2004. Cerato-platanin protein is located in the cell walls of ascospores, conidia and hyphae of Ceratocystis fimbriata f. sp. platani. FEMS Microbiology Letters 233: 341-346. 3. Scala A, Pazzagli L, Comparini C, Santini A, Tegli S and Cappugi G, 2004. Cerato-platanin, an early-produced protein by Ceratocystis fimbriata f. sp. platani, elicits phytoalexin synthesis in host and non-host plants. Journal of Plant Pathology 86: 23-29. 4. Bennici A, Calamassi R, Pazzagli L, Comparini C, Schiff S, Bovelli R, Mori B, Tani C and Scala A, 2005. Cytological and ultrastructural responses of Platanus acerifolia (Ait.) Willd. leaves to cerato-platanin, a protein from Ceratocystis fimbriata f. sp. platani. Phytopathologia Mediterranea 44: 153-161. 5. Pazzagli L, Pantera B, Carresi L, Zoppi C, Pertinhez TA, Spisni A, Tegli S, Scala A, Cappugi G, 2006. Cerato-platanin, the first member of a new fungal protein family: cloning, expression and characterization. Cell Biochemistry and Biophysics 44: 512-521
Sviluppo endofitico di Biscognauxia (= Hypoxylon) mediterranea in relazione a stress idrico e defogliazione da insetti in giovani piante di cerro. In A. Franceschini, F. Marras (eds.): L' endofitismo di funghi e batteri patogeni in piante arboree e arbustive. Sassari, Tempio Pausania
No full text
Nickel toxicity and peroxidase activity in seedlings of Triticum aestivum L.
No full textNi2+ toxicity was evaluated in Triticum aestivum L. by its effects on root and shoot length, dry matter production and water content. Over a threshold value of 20 mmol m 3 Ni2+ the degree of toxicity increases as a function of the Ni2+ concentration in the medium. Ni2+-treated roots show enhanced lipid peroxidation; the higher Ni2+ treatment (40mmol m 3) also increases leakage of K+. In roots and shoots, Ni2+ enhances both guaiacol and syringaldazine extracellular peroxidase activity. The increase in extracellular peroxidase activity is also associated with an increase in the phenolic contents of roots and shoots. The observed growth inhibition might be partly the result of the effect of Ni2+ on cell turgor and cell-wall extensibility. Intracellular soluble peroxidases are also stimulated by Ni2+; such effects, independently of the substrate, were detected in extracts of Ni2+-treated shoots at a lower Ni2+ concentration than in the roots. Intracellular peroxidases might act as scavengers of peroxide radicals produced as a result of nickel toxicity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
