1,720,975 research outputs found
Expression in different populations of cells of the root meristem is controlled by different domains of the rolB promoter
No full textCRF (CYTOKININ RESPONSE FACTOR) transcription factors in abiotic-stress and flowering time: from Arabidopsis thaliana to Lactuca sativa and Solanum lycopersicum.
No full textCharacterization of CRF (CYTOKININ RESPONSIVE FACTOR) transcription factor family in abiotic-stress response and flowering trait. From Arabidopsis thaliana to Lactuca Sativa and Solanum lycopersicum.
The abiotic stresses brought about by climate change, such as drought, floods, alterations in temperature and others, are altering important agronomic traits, such as the flowering time of vegetable species. This can have a negative impact on the abundance and organoleptic properties of the crops.
Adaptation to environment involves the accumulation of random mutations that can be fixed if they confer an evolutionary advantage. Genetic biodiversity in natural and domesticated plants populations is the richest source of allelic variants that are "tested" naturally by evolutionary mechanisms, and therefore is the most important resource for genetic improvement. More than 60% of adaptive mutations are associated with polymorphisms in transcription factors (TF) DNA sequences that leads to variations in the way they regulate their target genes in response of environmental and developmental signals. In facts, transcription represents the primary regulation level in determining an organism phenotype starting from his genotype. TF are thus the main target on which the process of adaptation of genotypes to the environment acts.
CRFs (CYTOKININ RESPONSIVE FACTOR) are ubiquitous TFs of the plant kingdom and are at central to the hormonal crosstalk between auxins and cytokinins, being induced by cytokinins and being at the same time regulators of auxin transporters (PINs). These TFs play fundamental roles both in plant development and abiotic stress responses and are at the core of the trade-off that takes place between the pathways involved in these traits.
In this project, the orthologs of clade III CRFs in the Brassicaceae model species Arabidopsis thaliana (CRF5 and CRF6) will be identified and characterized in the agriculturally relevant species Lactuca sativa (model for the Asteraceae family) and Solanum lycopersicum (model for the Solanaceae family) and the expression of these factors will be profiled in different tissues and conditions by qRT-PCR. Selected transcriptomic data available in public databases such as NCBI’s GEO will be analysed by k-means clustering analysis to identify co-expression modules related to stress response and flowering, to create Gene Coexpression Networks (GCNs), and to compare transcriptional networks between those species. In addition, collections of natural and domesticated varieties of the three species will be explored in silico, in search of mutations "selected" by the evolutionary process, which can confer resistance to the aforementioned stresses. The knowledge developed will be used for the genetic improvement of Lactuca sativa and Solanum lycopersicum, to create molecular markers that can be used to accelerate the breeding of new resilient crops that maintains their productive and organoleptic characteristics in the more variable and extreme environmental conditions that will characterize the upcoming decades
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
Genetic transformation of olive (Olea europaea L.) using Agrobacterium tumefaciens
No full textGenetic transformation of olive somatic tissues and zygotic embryos of the cv Dolce Agogia were obtained using Agrobacterium tumefaciens carryng the plasmid pBIN19 containing rol A, B, C from Agrobacterium rhizogenes T-DNA and kanamycin resistance gene neomycin phosphotransferase II (NPT II)
The overexpression of asparagine synthetase A from E. coli affects the nitrogen status in leaves of lettuce (Lactuca sativa L.) and enhances vegetative growth
No full textThe asparagine synthetase A (EC 6.3.1.1) of E. coli (AS-A) mainly uses ammonia to produce asparagine, a key nitrogen transporter in plants. The AS-A encoding gene (asnA) was expressed constitutively in lettuce cultivar ‘Cortina’ under the control of pMAC, a chimerical promoter, to induce phenotypical alterations of plant growth and quality as a consequence of nitrogen status changes. Nine fertile
transgenic lines harbouring independent T-DNA insertions were recovered. Primary transformants shared new visible traits such as a higher leaf number and wider leaf surface than the wild-type. The progeny of three primary transformants stably maintained these phenotypes, to which the synthesis of both asnA transcript and protein were associated. In pMAC:asnA plants, seed germination, formation and development of leaves, bolting and flowering occurred earlier than non-transformed plants.
Twenty-eight days after sowing (das), transgenic
plants showed a ca. 1.3 increase of leaf area and dry
weight as compared to the wild-type. Moreover, the
contents of asparagine, aspartic acid and glutamine,
but not that of glutamic acid, of pMAC:asnA young
plants (21 das) were greater than the wild-type. The level of total soluble protein was higher in transgenic than in non-transformed leaves borne on plants at 35, 50 and 75 das. A decrease of nitrate was also measured in pMAC:asnA leaves with respect to non-transformed ‘Cortina’, in transgenic populations at 60 das. In pMAC:asnA genotypes, the altered content of nitrogen transport amino acids, the tolerance
to increasing doses of ammonium and phosphinothricin indirectly proved the AS-A enzymatic activity in lettuce
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
Genome editing protocols and genetic diversity tools for flowering time adaptation in Asteraceae
No full textClimate change is leading to a negative alteration of ecological balances and consequently in yield and quality of crops. Therefore, it is necessary developing new fast and precise breeding techniques to select more robust and tolerant crops with increased quality and yields under more extreme conditions. Genome editing is a molecular tool allowing to accelerate breeding processes and the study of important agronomic traits.
The purpose of our work is to develop new efficient genome editing (GE) protocols, including DNA-free GE techniques, for Lactuca sativa and Cichorium endivia to improve important adaptation traits such as flowering time.
Both species, belonging to the Cichoriae tribe in the Asteraceae family, are particularly interesting for their agronomical characteristics. Lettuce is one of the most popular leafy vegetables. It represents a genetic model for leafy species due to the small size of its genome (2.5 Gb), short reproductive cycle and suitability for tissue culture. Moreover, a reference sequenced genome with detailed genetic maps is available. C. endivia (endive chicory and escarole), a traditional horticultural species, has received increasing interest for the vegetable market for its nutritional value and valuable properties for human health. Although its genome sequence is not public yet, several features make it also a suitable model for leafy crops.
The time at which flowering occurs plays a major role in leafy crops production, it affects the quality and quantity of leaves as well as adaptation to different environmental conditions. The transitioning to reproductive growth is marked by the elongation of the stem (bolting), that renders the crop bitter and unmarketable. Heat-accelerated bolting and flowering is a common phenomenon that impacts agricultural production of diverse lettuce and Cichorium spp. cultivars.
As important GE targets for flowering time, our work focused on SOC1, a MADS box transcription factor that integrates flowering signals with environmental cues, and STM, a KNOTTED1-LIKE homeobox protein involved in apical transition from vegetative to reproductive phase. As genetic diversity constitutes a source of allelic variants "tested" naturally in the field of evolution, we first searched for SOC1 and STM allelic variants that could fine tune these genes function in 1135 accessions of A. thaliana. Polymorphisms were searched in both coding sequences (CDS) and regulatory promoter regions. Comparative analyses were performed in the genomes of L. sativa cultivars and wild relatives.
In order to study the function of SOC1 and STM homologs in L. sativa and C. endivia, the obtainment of overexpression and GE constructs is in progress. Furthermore, efficient hairy root transformation protocols have been set up to test the efficiency of GE constructs
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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