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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
Cerato-platanin shows expansin-like activity on cellulosic materials.
No full textCerato-platanin (CP) is a protein elicitor produced by Ceratocystis platani, the causal agent of canker stain of plane tree. The eliciting activity of CP has been extensively studied, and in accordance with the “zig-zag model” described by Jones and Dangl (2006), CP may be considered a PAMP (pathogen-associated molecular pattern). However, the primary role of CP and of all the
other proteins of the “cerato-platanin family” in fungi is unknown. CP is both a structural component of the cell wall of C. platani and a protein secreted in the medium where the fungus
grows. No lytic activity has ever been reported. Recently, by studying the three-dimensional structure of the protein and the pattern of gene expression, a clue on its role has been found: CP
could act in the remodelling and enlargement of the cell wall during hyphal growth and in the formation of chlamydospores, with a role like that of expansins. In the present work, the expansinlike activity of CP was investigated. Like expansins, CP was able to disrupt filter paper in a concentration-dependent manner and to cause fragmentation of the crystalline cellulose Avicel. Cotton fibers incubated for 24 h with CP, then sonicated, showed breakage and defibration, whereas fibers incubated in buffer alone remained undamaged. Optimum of pH and temperature for CP activity were determined. Results strongly suggest that CP may be a new fungal expansin. Its possible synergistic effect with cellulases is under investigation
Cerato-platanin shows expansin-like activity on cellulosic materials
No full textCerato-platanin (CP) is a non-catalytic protein with a double ψβ-barrel fold located in the cell wall of the phytopathogenic fungus Ceratocystis platani. CP is released during growth and induces defence-related responses in plants. CP is also the first member of the "cerato-platanin family" (CPF) (Pfam PF07249). In the CPF, the molecular mechanism of action on plants and above all the biological role in fungal life are little-known aspects. However, an expansin-like function has recently been suggested concerning CP. Expansin-like proteins have the ability to act non-hydrolytically on cellulose. In the present work, the expansin-like activity of CP and Pop1, a CP family member, was investigated. Like expansins, CP and Pop1 were able to weaken filter paper in a concentration-dependent manner and without the production of reducing sugars. A metal-dependent polysaccharide monooxygenase-like activity was excluded. The optimum of activity was pH 5.0, 38 °C. CP was also able to cause fragmentation of the crystalline cellulose Avicel and the breakage and defibration of cotton fibres. However, the interaction did not involve a stable bond with the substrates and CP did not significantly enhance the hydrolytic activity of cellulase. On the other hand, CP and Pop1 bound quickly to chitin. We consider CP as a novel one-domain expansin-like protein. We propose a structural role for CP in the fungal cell wall due to the ability to bind chitin, and hypothesize a functional role in the interaction of the fungus with the plant for the weakening activity shown on cellulose
Early transcription of defence-related genes in Platanus acerifolia leaves after treatment with cerato-platanin and cerato-populin
No full textCerato-platanin (CP) and cerato-populin (Pop1) are small non-catalytic proteins produced by the ascomycetes Ceratocystis platani and C. populicola. C. platani is responsible for the canker stain disease of plane trees, and C. populicola for the black canker of poplar trees. CP and Pop1 are PAMPs (pathogen-associated molecular patterns) inducing typical defense responses in various host and non-host plants. CP causes the up-regulation of defence-related genes in Platanus acerifolia leaves treated for 48 hours. However, other defence-related events like cell plasmolysis and localized resistance occur before 48 hours. With the present work, the transcriptional changes caused by CP in P. acerifolia leaves were studied during the first 24 hours. A cDNA microarray containing both P. acerifolia transcripts induced by CP after 48 hours (Baccelli et al. 2008, Fontana et al. 2008) and poplar transcripts induced by cold or ozone (Rizzo et al. 2007, Maestrini et al. 2009) was designed to study the gene regulation induced by CP at 24 hours. Out of 318 cDNA sequences present on the microarray, 131 turned out to be differentially regulated in P. acerifolia leaves after 24 hours of treatment with CP. Out of the 131 modulated transcripts, 86 new sequences of P. acerifolia differentially regulated by CP, 35 up-regulated and 51 down-regulated, were found; these new CP-responsive genes were grouped in seven functional categories. Interestingly, the microarray contained 100 P. acerifolia transcripts known to be up-regulated by CP after 48 hours of treatment, but only 36 were also up-regulated after 24 hours. In order to confirm the microarray analysis, quantitative PCRs (qPCRs) were performed on five selected transcripts. Although with some differences, qPCR data validated the microarray results. The transcripts used to validate the microarray result were also selected to carry out a time-course analysis in P. acerifolia leaves treated with CP also comparing the eliciting activity of CP with Pop1. CP and Pop1 were able to induce early transcriptional changes, confirming that PAMPs act at gene transcription level very quickly after their perception
Twenty years of research on cerato-platanin family proteins: clues, conclusions, and unsolved issues
No full textTwenty years of research on cerato-platanin family proteins (CPPs) have led to some clear conclusions: CPPs are exclusively present in the fungal kingdom and possess an outstanding capacity to stimulate the immune system of plants. Recent discoveries have highlighted remarkable structural and functional similarities between CPPs and expansins, a class of non-enzymatic proteins found in both plants and microbes possessing loosening ability on the cell wall structure. Nevertheless, the determination of a biological role for CPPs in fungi is becoming a complicated puzzle to solve, since experimental data are often divergent and point to functional diversification. A general consensus appears however possible: CPPs from pathogenic and beneficial fungi may be considered as microbe-associated molecular patterns (MAMPs) and likely play a dual role, exerting functions in the fungal cell wall and/or in plant colonization. In this review, which celebrates 20 y of research on CPPs, we trace the history of these proteins and highlight experimental evidence and still unsolved issues
Early transcription of defence-related genes in Platanus acerifolia leaves following treatment with cerato-platanin
No full textThe protein elicitor cerato-platanin (CP) is known to induce defence-related responses in various plants. Some of these responses occur very quickly. In the present work, the transcriptional changes caused by CP in leaves from Platanus acerifolia were studied during the first 24 hours.
With a cDNA microarray 131 differentially regulated transcripts were identified as responsive to CP after 24 hours of treatment. Eighty-six of these were cold- or ozone-modulated transcripts from poplar, thus revealing a significant overlap between genes responsive to CP and to cold/ozone stress. The transcriptional changes caused by CP were compared with Pop1, a CP-orthologous protein, in a time-course analysis performed after 3, 6, 12 and 24 hours by real-time RT-PCR on five defence-related genes. CP and Pop1 were able to induce early transcriptional changes (WRKY was overexpressed after only 3 hours), although the two proteins acted differently on gene transcription
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
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