1,720,976 research outputs found
Next Generation Sequencing applied to Cultural Heritage: detection of microorganisms present on the parchment surface of an ancient Gradual of the 13th century
No full textThe original integrity of Cultural Heritage (CH) may be threatened by the microbial deterioration. Conservation strategies to prevent biodeterioration needs the identification of microorganisms colonizing the substrate. In the last decades microbial monitoring has relied on culture-dependent methods. The most significant limit is the cultivability of the microorganisms and their following identification. In recent years, the development of next generation sequencing (NGS) approach provided new tools for their identification.
We design and apply a diagnostic protocol on an ancient Gradual of the 13th century by using a targeted metagenomic analysis carried out by Nanopore Technologies consisting of: 1) Non-invasive sampling (sterile swab); 2) DNA extraction; 3) whole genome pre-amplification (WGA); 4) PCR amplification of conserved regions ITS (fungi), 16S (bacteria) and 18S (eukaryotes); and 5) amplicon-sequencing with MinION (ONT). Fungal species identified as Serpula lacrymans, Postia, and Alternaria alternata, may be related to wood degradation (in fact the cover of the manuscript is made of wood), while Aspergillus sp. and Penicillium sp. to parchment degradation. For bacteria instead: Cutibacterium acnes, Finegoldia magna, Bacillus mansiliensis, and Staphylococcus epidermidis, all related to the human skin flora, and which therefore could be present due to handling over the years. Their presence could pose a risk for the Gradual preservation since these species can degrade collagen naturally present in the parchment. This work shows that the NGS applied to CH may produce valuable insight, for the diagnostic of potential threats of biodeterioration
Auxin regulates Arabidopsis anther dehiscence, pollen maturation, and filament elongation
No full textWe provide evidence on the localization, synthesis, transport, and effects of auxin on the processes occurring late in Arabidopsis thaliana stamen development: anther dehiscence, pollen maturation, and preanthesis filament elongation. Expression of auxin-sensitive reporter constructs suggests that auxin effects begin in anthers between the end of meiosis and the bilocular stage in the somatic tissues involved in the first step of dehiscence as well as in the microspores and in the junction region between anther and filament. In situ hybridizations of the auxin biosynthetic genes YUC2 and YUC6 suggest that auxin is synthesized in anthers. In agreement with the timing of auxin effects, the TIR1, AFB1, AFB2, and AFB3 auxin receptor-encoding genes are transcribed in anthers only during late stages of development starting at the end of meiosis. We found that in tir1 afb triple and quadruple mutants, anther dehiscence and pollen maturation occur earlier than in the wild type, causing the release of mature pollen grains before the completion of filament elongation. We also assessed the contribution of auxin transport to late stamen developmental processes. Our results suggest that auxin synthesized in anthers plays a major role in coordinating anther dehiscence and pollen maturation, while auxin transport contributes to the independent regulation of preanthesis filament elongation
ROX1, a gene induced by rolB, is involved in procambial cell proliferation and xylem differentiation in tobacco stamen
No full textThe Agrobacterium rhizogenes oncogene rolB mimics the effects of auxin in that it increases the sensitivity of transformed cells to this hormone. Here we isolated a tobacco gene, ROX1, acting downstream of rolB. We show that plants with reduced levels of ROX1 mRNA, due to the expression of a 35S-driven ROX1-antisense construct, have flowers with stamens and pistils longer than normal because of an increased number of cells. Localized expression of rolB in anthers results in overexpression of ROX1 and reduced growth of stamens, due to a reduced number of cells. In addition, the longer stamens of antisense plants show a delayed xylem differentiation in the lateral bundles, primarily of the junction region between anther and filament, while the shorter stamens of ROX1-overexpressing plants show a precocious differentiation of xylem cells in the same tissues. Expression of ROX1 in stamens peaks at early stages of stamen growth, and ROX1 mRNA is localized mostly in anther procambial cells. The sequence of ROX1 shares a conserved element with a number of plant genes, including TED3, which is involved in xylem differentiation. These results point to a role of ROX1 in the balance between proliferation of procambial cells and xylem differentiation during stamen development
ABCB1 and ABCB19 auxin transporters have synergistic effects on early and late Arabidopsis anther development
No full textArabidopsis abcb1 abcb19 double mutants defective in the auxin transporters ABCB1/PGP1 and ABCB19/PGP19 are altered in stamen elongation, anther dehiscence and pollen maturation. To assess the contribution of these transporters to stamen development we performed phenotypic, histological analyses, and in situ hybridizations on abcb1 and abcb19 single mutant flowers. We found that pollen maturation and anther dehiscence are precocious in the abcb1 but not in the abcb19 mutant. Accordingly, endothecium lignification is altered only in abcb1 anthers. Both abcb1 and abcb1 abcb19 stamens also show altered early development, with asynchronous anther locules and a multilayer tapetum. DAPI staining showed that the timing of meiosis is asynchronous in abcb1 abcb19 anther
locules, while only a small percentage of pollen grains are nonviable according to Alexander’s staining. In agreement, TAM (TARDY ASYNCHRONOUS MEIOSIS), as well as BAM2 (BARELY ANY MERISTEM)—involved in tapetal cell development—are overexpressed in abcb1 abcb19 young flower buds. Correspondingly, ABCB1 and ABCB19 mRNA localization supports the observed phenotypes of abcb1 and abcb1 abcb19 mutant anthers. In conclusion, we provide evidence that auxin transport plays a significant role both in early and late stamen development: ABCB1 plays a major role during anther development, while ABCB19 has a synergistic role
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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