1,723,974 research outputs found
Investigating the molecular targets of Apple Proliferation Phytoplasma effector SAP11CaPM in apple
No full textApple Proliferation (AP) is a phytoplasma-related associated with 'Candidatus Phytoplasma mali' ('Ca. P. mali'). Trees affected by the disease display several symptoms associated with plant shape and development, ultimately leading to the generation of non-marketable fruits. The disease is widespread in many apple cultivated areas of Europe, where outbreaks in recent years caused huge economic losses. There is no cure or treatment for phytoplasmoses but to control the vector insects, the uprooting of affected trees and the use of healthy propagation material. In the last years, extensive research led to the identification of AP-tolerant experimental rootstock, but the molecular basis of this inheritable trait is unknown.
Phytoplasmas secrete pathogenic proteins, called effectors, that affect the host physiology and determine a fitness advantage for the bacteria. Among these, the best characterized in 'Ca. P. mali' is SAP11CaPM, which was observed to target and deactivate two M. × domestica transcription factors of the TCP family, i.e., MdTCP4a and MdTCP13a. This work aims to investigate the molecular targets of SAP11CaPM to shed light on the molecular basis of disease development and the phenomenon of tolerance.
The second chapter consists of a revision of the MdTCP gene family set by performing a re-identification on the latest high-quality M. × domestica genome assembly. Of the 52 MdTCP sequences previously described, 15 were discarded because of redundancy with other MdTCPs (six) or the absence of a complete open reading frame (nine). Of the 37 remaining MdTCP sequences, 30 were observed to be included in the list of functionally annotated genes automatically computed. Furthermore, three novel MdTCP sequences have been identified, for a total of 40 sequences constituting the revised set of the MdTCP gene family. Analysis of the intergenic identity, combined with the synteny analysis previously performed on the whole M. × domestica genome, allowed the identification of 15 pairs of genes that likely originated through a recent whole-genome duplication event. Finally, the 40 MdTCP sequences identified were named according to the homology with A. thaliana TCP.
In chapter 3, the sequences of the two SAP11CaPM-target genes have been analyzed in susceptible and tolerant genotypes to screen for potential differences that could explain the tolerant behaviour displayed by some plants. Sequence analyses led to the identification of two rare amino acid substitutions in MdTCP4a, of which one, in particular, was not found in any of the TCP sequences published to date. The interaction between the bacterial effector and the protein alternatives from susceptible and tolerant genotypes was measured both in a heterologous system (Y2H) and in planta (BiFC). The interaction assays showed no difference in the interaction strength between the different alternatives, suggesting that this mechanism cannot explain the tolerant phenotype. Nonetheless, a good degree of correlation between the presence of the two amino acid substitutions and tolerance to AP was found, indicating a possible role of these sequences as genetic markers of tolerance.
Finally, chapter 4 describes the generation and characterization of M. × domestica transgenic plants overexpressing the two MdTCP genes via At-mediated transformation. While plants overexpressing MdTCP13a died shortly after the regeneration, suggesting that overexpression of this gene can hinder the plant development, several independent MdTCP4a-overexpressing transgenic lines could be generated. Transgenic lines kept in vitro showed a low level of overexpression and no differences in phenotype compared to non-transformed plants.Following the soil acclimatization, the transgenic plants demonstrated an increase in the overexpression level and displayed some peculiar phenotype characteristics, such as smaller and crinkled leaves, loss of apical dominance, and generation of more shoots than non-transformed. In vitro transgenic plants were infected with 'Ca. P. mali' using the micrografting technique and were screened for the presence of phytoplasma with a qPCR assay. Results show that two out of three transgenic lines tested display a phytoplasma concentration significantly lower than non-transformed, which is commonly associated with less severity or complete absence of symptoms. Furthermore, the transcriptomes of three soil acclimatized lines have been analyzed via RNAseq, and preliminary analyses show an up-regulation of several genes associated with plant development and abiotic stress responses
Richardo Tabarelli, De Deo Uno et De Gratia Christi, 2 vol., 1962
No full textJossua Jean-Pierre. Richardo Tabarelli, De Deo Uno et De Gratia Christi, 2 vol., 1962. In: Revue des Sciences Religieuses, tome 39, fascicule 2, 1965. p. 199
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Measurement of the neutrino-oxygen neutral-current interaction cross section by observing nuclear deexcitation gamma rays
No full textWe report the first measurement of the neutrino-oxygen neutral-current quasielastic (NCQE) cross section. It is obtained by observing nuclear deexcitation γ rays which follow neutrino-oxygen interactions at the Super-Kamiokande water Cherenkov detector. We use T2K data corresponding to 3.01×1020 protons on target. By selecting only events during the T2K beam window and with well-reconstructed vertices in the fiducial volume, the large background rate from natural radioactivity is dramatically reduced. We observe 43 events in the 4-30 MeV reconstructed energy window, compared with an expectation of 51.0, which includes an estimated 16.2 background events. The background is primarily nonquasielastic neutral-current interactions and has only 1.2 events from natural radioactivity. The flux-averaged NCQE cross section we measure is 1.55×10-38cm2 with a 68% confidence interval of (1.22,2.20)×10-38cm2 at a median neutrino energy of 630 MeV, compared with the theoretical prediction of 2.01×10-38cm2
Variations on the Author
No full text“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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