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Individuazione di ‘Candidatus phytoplasma ziziphi’ in drupacee in Italia.
No full textDuring the last years in two different areas of northern Italy in which cherry and peach trees are mainly grown it was observed a severe symptomatology that leads plants to decline and die in two-weeks/one month maximum. From the beginning of the summer the affected plants show leaves of smaller size, with chlorosis, reddening, curling aspect, and premature fall; young branches also show some lack of lignifications. Preliminary tests allow to exclude the presence of several biotic or abiotic agents therefore to verify the possible phytoplasma association with the disease, nucleic acid extraction was performed from leaf midribs as well as from phloem scrapes of declining trees. Chloroform/phenol extraction (Prince et al., 1993) was applied before molecular analyses that were then carried out by nested PCR with primers amplifying 16S rDNA, spacer region and part of the 23S region. Samples positive with R16RF2/R2 primers were subjected to RFLP analyses with MseI, RsaI, and HpaII (Lee et al., 1998), restriction profiles obtained from peach and cherry samples were undistinguishable from each others and were identical to the reference sample JWB (jujube witches’ broom) employed as control, therefore the phytoplasmas detected were attributed to ribosomal subgroup 16SrV-B. The further use of CJF1/R1 (Zhu et al., 1977) subgroup 16SrV-B specific primers allow to confirm this identification. Sequencing of R16F2/R2 amplicons obtained from one sample of peach and one of cherry respectively was also performed. After aligning and comparing these sequences with those in GenBank it was possible to determine the presence of 99% homology with sequence AB052877, Candidatus Phytoplasma ziziphi recently described (Jung et al., 2003).
It is know from literature that in areas where peach and cherry are mainly cultivated severe phytoplasma diseases often occur, but they are associated with diverse agents: 16SrX-B in Europe, 16SrIII-A in Canada and California, 16rVII-A in Sicily, 16SrV-B in India and China, 16SrXII-A in Italy and Chile. The detection of jujube witches’ broom subgroup phytoplasmas is however reported for the first time in Italy and this must to be taken into consideration for possible epidemic outbreaks. It is important to continue the monitoring at national level in order to verify the real diffusion and spreading of this phytoplasma in Italian cultivations
L’esperienza decennale del Veneto sui giallumi: Flavescenza datata stabile e legno nero in crescita.
No full textDifesa e prevenzione contro la flavescenza dorata messe in atto
sin dalle prime segnalazioni sono state efficaci nel contenere
la malattia, che oggi è presente in forma endemica e causa problemi
solo localmente. Recentemente preoccupa la continua espansione
del fitoplasma del legno nero
Molecular identification and geographic distribution of Flavescence dorée phytoplasma strains.
No full textMolecular analyses were carried out using two markers for Flavescence doreée (FD) phytoplasmas covering 16S ribosomal plus spacer region and translocase genes, in order to study FD strains present in Italy, Serbia, and France. The results confirm that Serbian FD strains belong to 16SrV-C subgroup. Both 16SrV-C and -D subgroups were still detected in Italy, and strains from both subgroups were studied in Veneto, while in Emilia and Tuscany 16SrV-D and 16SrV-C strains were respectively studied. Three of the four FD strains from France belong to 16SrV-D subgroup, while one was differentiable on 16S ribosomal gene from all others studied. By RFLP analyses on traslocase gene it was possible to differentiate subtypes in both ribosomal subgroups confirming ability of FD phytoplasmas to differentiate genotypes
‘Flavescence dorée’ phytoplasma strain differentiation on the translocase (secY) gene
No full text‘Flavescence dorée’ (FD) associated phytoplasmas are molecularly distinguished in strains belonging to 16SrV-C and -D that are geographically separated in the majority of the European Countries where the disease was reported. While the subgroup differen-tiation on the 16S ribosomal gene is quite stable, RFLP analyses on the translocase gene allow differentiation of subtypes in both subgroups confirming ability of FD phytoplasmas to rapidly differentiate lineages
Molecular variability on 16S rDNA of ‘bois noir’ phytoplasmas in grapevine from Italy and Serbia
No full textSurveys carried out to identify ‘bois noir’ (BN) phytoplasmas in grapevine yellows outbreaks in vineyards located in Serbia and in several Italian regions were carried out from 2008 to 2010. The presence of BN phytoplasmas was preliminarily demonstrated by RFLP analyses with TruI restriction enzyme on R16F2/R2 amplicons. About 60 samples were selected for further molecular characterization. Reference strains maintained in periwinkle were STOL (from Serbia), STOLC and STOL-PO (from France). RFLP analyses on R16F2/R2 amplicons with Hpy188I, Hpy8I, MboI, MboII, TruI, RsaI, BstUI, AluI, and Tsp509I restriction enzymes were carried out. Tsp509I was only differentiating one samples from Veneto region in Italy, while different profiles were observed in several of the examined samples when MboII, Hpy188I, and AluI were used. In particular, three different profiles were observed with AluI in samples from Veneto and Tuscany (Italy), and Serbia. Using MboII four different profiles (a-b-c-d) were observed in samples from Veneto, Tuscany and Emilia, while only one of them (profile a) was observed in the samples from Serbia. RFLP profiles of reference strains were a for STOL, b for STOL-PO and c for STOLC. Considering that the profile c is referring to an amplicons longer than the expected one, the presence of interoperon heterogeneity and/or of mixed BN strain infection could be hypnotized for this profile. Some of the samples having profile c when digested with Hpy188I showed further polymorphism.
The reference strains plus 7 field collected BN strains chosen among those showing the above described polymorphisms were sequenced on the full 16S gene. The sequences were assembled using DNA STAR software, and compared with selected sequences of phytoplasmas in GenBank database using Blast N 2.2.18. Obtained aligned sequences ranged from 1,300 to 1,500 bp, all showing 99% homology among them self and with several of the 16SrXII-related strains deposited in Genbank. Virtual RFLP analyses on R16F2/R2 amplicons were carried out, using pDRAW32 program (AcaClone Software) and it was possible to confirm the variability detected in real RFLP analyses in the majority of BN sequenced strains. The comparison between real and virtual RFLP analyses showed in some cases different profiles when digested with MboII. Strain STOLC showed in this case a b profile confirming that profile c is formed by mixed infection or interoperon heterogeneity. On the other hand the presence of a d profile was detected in one of the sequenced strains from Serbia showing an a profile in RFLP analyses. BN strains differentiation on 16S rDNA on field collected uncloned amplicons indicates that the detected variability could be related with different epidemiological behaviours
Differentiation among “Candidatus Phytoplasma mali” strains by multiple genes analyses
No full textSamples from apple plants infected by apple proliferation (AP) phytoplasmas of different varieties and from diverse areas were examined by different molecular marker to verify strains differentiation. In the 16S plus spacer region two profiles (P-I and P-II) were distinguished. P-I profile was detected in reference strains, in samples from Serbia, and in the majority of samples from Trentino (Italy); the P-II profile was prevalent in samples from Veneto (Italy); both profiles were identified in samples from Hungary, in some cases both together in the same sample. The analyses of rpl22-s3 genes allow to identify in all the samples showing a P-I profile presence of phytoplasmas belonging to rpX-A subgroup, while in the samples showing a P-II profile it was possible to distinguish the other three reported rpX subgroups. In samples from Italy phytoplasmas belonging to rpX-D, rpX-B and rpX-C subgroups were identified with further local differences. RFLP analyses on AP13/AP10 amplicons differentiate among strains belonging to the rpX-A subgroup: the samples from Serbia show AP profiles, while those from Italy show AT-2 profiles. In the samples from Hungary the presence of AT1, AT2, and AP profiles was identified. The combined use of these three molecular markers allows differentiating ‘Candidatus Phytoplasma mali’ strains according with geographical and, in some cases, also with epidemic distribution. In several orchards of Veneto vector monitoring by yellow sticky traps was carried out and Cacopsylla melanoneura was consistently detected, while Fieberiella florii was erratically found, and only one specimen of Cacopsylla picta was captured. Work is in progress to further verify epidemiological application of these molecular markers for AP strain characterization in insect vector and in alternative host plants
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
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