1,721,020 research outputs found
Transcriptomic analysis of wound xylem formation in Pinus canariensis
No full textWoody plants, especially trees, usually must face several injuries caused by different agents during their lives. Healing of injuries in stem and branches, affecting the vascular cambium and xylem can take several years. In conifers, healing takes place mainly from the remaining vascular cambium in the margin of the wound. The woundwood formed in conifers during healing usually presents malformed and disordered tracheids as well as abundant traumatic resin ducts. These characteristics affect its functionality as water conductor and its technological properties
Differential gene expression analysis of the resprouting process in Pinus canariensis provides new insights into a rare trait in conifers
No full textTranscriptomic analysis of wound xylem formation in Pinus canariensis
No full textAbstract Background Woody plants, especially trees, usually must face several injuries caused by different agents during their lives. Healing of injuries in stem and branches, affecting the vascular cambium and xylem can take several years. In conifers, healing takes place mainly from the remaining vascular cambium in the margin of the wound. The woundwood formed in conifers during healing usually presents malformed and disordered tracheids as well as abundant traumatic resin ducts. These characteristics affect its functionality as water conductor and its technological properties. Results In this work we analyze for the first time the transcriptomic basis of the formation of traumatic wood in conifers, and reveal some differences with normal early- and late-wood. Microarray analysis of the differentiating traumatic wood, confirmed by quantitative RT-PCR, has revealed alterations in the transcription profile of up to 1408 genes during the first period of healing. We have grouped these genes in twelve clusters, according to their transcription profiles, and have distinguished accordingly two main phases during this first healing. Conclusions Wounding induces a complete rearrangement of the transcriptional program in the cambial zone close to the injuries. At the first instance, radial growth is stopped, and a complete set of defensive genes, mostly related to biotic stress, are induced. Later on, cambial activity is restored in the lateral borders of the wound, even at a high rate. During this second stage certain genes related to early-wood formation, including genes involved in cell wall formation and transcription factors, are significantly overexpressed, while certain late-wood related genes are repressed. Additionally, significant alterations in the transcription profile of abundant non annotated genes are reported
Differential gene expression analysis of the resprouting process in Pinus canariensis provides new insights into a rare trait in conifers
No full textAbstract Resprouting is crucial in population dynamics in response to wildfires or herbivory. This trait, common in angiosperms, is considered rare in conifers, being Pinus canariensis one of the few species able to resprout. We analyzed gene expression during wound-induced resprouting in 5 years-old Canarian pines. RNA was extracted at three different stages, including control samples from remote branches, representing immediate response to wounding (R0), resprouting initiation (R1), and elongation (R2), and then hybridized to a microarray designed with 15,000 cDNAs from Pinus canariensis transcriptome of meristematic activity. We found 1164 Differentially Expressed Genes (DEGs), of which 903 were significant in R0, 278 in R1, and 261 in R2. Genes related to defense- and stress-response were mainly found to be overexpressed at R0, while DEGs coding for transcription factors such as GROWTH-REGULATING FACTOR (GRF), FLOWERING-PROMOTING FACTOR (FPF), and the HOMEODOMAIN LEUCINE ZIPPER Class IV (HD-ZIP IV), mainly related to outgrowth processes and lateral organogenesis in plants, showed overexpression at R1 and R2, when new shoots were emerging. This data was compared to differential gene expression during apical growth in P. canariensis , suggesting similarities between vegetative apical growth and regulation of lateral shoot development in response to mechanical wounding, but also yielding 32 DEGs exclusively overexpressed at some point during resprouting stages (R1 and/or R2). The implication of such transcription factor families, with important roles in leaf and inflorescence development also in flowering plants, suggests underlying homologies between common lateral organogenesis processes in angiosperms and resprouting in gymnosperms.Ministerio de Ciencia e Innovación http://dx.doi.org/10.13039/501100004837Organismo Autónomo de Parques Nacionales http://dx.doi.org/10.13039/100015865Seventh Framework Programme http://dx.doi.org/10.13039/501100004963Georg-August-Universität Göttingen http://dx.doi.org/10.13039/50110000338
Transcriptomic analysis of juvenile wood formation during the growing season in <i>Pinus canariensis</i>
No full textAbstract
A noticeable proportion of low transcribed genes involved in wood formation in conifers may have been missed in previous transcriptomic studies. This could be the case for genes related to less abundant cell types, such as axial parenchyma and resin ducts, and genes related to juvenile wood. In this study, two normalized libraries have been obtained from the cambial zone of young individuals of Pinus canariensis C. Sm. ex DC, a species in which such cells are comparatively abundant. These two libraries cover earlywood (EW) and latewood (LW) differentiation, and reads have been de novo meta-assembled into one transcriptome. A high number of previously undescribed genes have been found. The transcriptional profiles during the growing season have been analyzed and several noticeable differences with respect to previous studies have been found. This work contributes to a more complete picture of wood formation in conifers. The genes and their transcription profiles described here provide a useful molecular tool for further studies focused on relevant developmental issues, such as wound response and the formation of traumatic wood, re-sprouting, etc., presumably related to those cells.</jats:p
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
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