1,720,974 research outputs found
Dependence of nanoparticle-cell recognition efficiency on the surface orientation of scFv targeting ligands
No full textThe surface activation of multifunctional nanoparticles (MNPs) with peptide ligands directing their targeting to cancer cells is an emerging research area in nanobiotechnology. In this paper, water-soluble MNPs have been synthesized and functionalized with an scFv antibody variant specific toward the HER2 receptor overexpressed in several breast cancer cell lines. The scFv was genetically engineered to introduce a cysteine residue inside the loop sequence bridging the VH and VL lobes of the molecule and a histidine tag at the C-terminus in the VL fragment. The Cys and 6 × His functionalities were exploited as orthogonal reactive groups driving the scFv conjugation to MNPs. In this way, scFv positioning on the MNP surface was forced into two different orientations depending on the molecular binding site used for conjugation. The resulting scFv-functionalized MNP1 and MNP2, respectively, were assessed as to their labeling efficiency and selectivity to HER2-positive MCF7 cells. We demonstrate that, while both MNP1 and MNP2 were selective for HER2, there is a remarkable preference for scFv presentation with VH and VL lobes concurrently available for receptor recognition (MNP1) in terms of cell binding efficiency, suggesting that ligand orientation may strongly affect cell binding from MNPs. This journal is © The Royal Society of Chemistry
Genetics and Evolution of Abiotic Stress Tolerance in Plants
No full textThis reprint represents a wide vision of what and how the research on plants at molecular level (genetics, genomics, transcriptomics, proteomics, metabolomics, and so on) contribute to a good equilibrium among human needs, food security, and future strategies for mitigating the effects of global climate changes. Now more than ever, understanding the genetics and evolution of the gene mechanisms and the networks of different molecular pathways acting on plant abiotic stress tolerance has an important role to find new solutions for modern agricultural problems. Scientists have the relevant task of increasing knowledge in the complex area of plant genetics and genomics, the genes responsive to specific abiotic stresses (such as drought, salts, or heat) and their inducible promoters, and various gene expression control and modulation mechanisms, including alternative splicing, micro-RNA interference, post-transcriptional mRNA decay, and post-translational protein degradation. At the same time, evolution has played a key role in the establishment of the current traits, so that major insights into the genetic diversity producing different alleles, adaptation, phylogenesis, and evolution of genomes and gene families can be translated and applied as tools for developing new tolerant plant varieties capable of satisfying the needs in terms of food security, protection of the planet, and conservation and recovery of natural resources such as water and soils. This reprint is full of technical and specialized terms and, for this reason, it is addressed to scientists and students trained in plant functional genomics, breeding, agronomy, and genetics. It seems an exciting virtual tour through plant molecular responses to various environmental stresses and new ideas and applications will be derived. I wish to thank all colleagues and authors who contributed with their valuable work to the success of this Special Issue, submitting their articles, up to the publishing the present reprint. Furthermore, I wish to thank the MDPI Editorial group and the Genes editorial officers for their constant help and presence along all period dedicated to this Special Issue
Expression Analysis of the TdDRF1 Gene in Field-Grown Durum Wheat under Full and Reduced Irrigation
Full text linkSome of the key genes and regulatory mechanisms controlling drought response in durum wheat have been identified. One of the major challenges for breeders is how to use this knowledge for the achievement of drought stress tolerance. In the present study, we report the expression profiles of the TdDRF1 gene, at consecutive plant growth stages, from different durum wheat genotypes evaluated in two different field environments. The expression of a possible target gene (Wdnh13) of the TdDRF1 gene was also investigated and analogies with the transcript profiles were found. The results of the qRT-PCR highlighted differences in molecular patterns, thus suggesting a genotype dependency of the TdDRF1 gene expression in response to the stress induced. Furthermore, a statistical association between the expression of TdDRF1 transcripts and agronomic traits was also per-formed and significant differences were found among genotypes, suggesting a relationship. One of the genotypes was found to combine molecular and agronomic characteristics
Structural characterization of the DRF1 gene of Aegilops speltoides and comparison of its sequence with those of B and other Triticeae genomes
Full text linkThe genus Aegilops L. has been intensively investigated due to its close relationship with wheat (Triticum L.) as contributor of B and D subgenomes. Because of their vast genetic diversity, Aegilops species represent a rich source of alleles of agronomic interest, which could be used to widen the wheat gene pool and improve tolerance to diseases, pests, drought, cold and other environmental stresses. We report the isolation and characterization of the Dehydration Responsive Factor 1 (DRF1) gene in three accessions of Ae. speltoides coming from different regions of the Fertile Crescent. The DRF1 gene belongs to the DREB gene family and encodes transcription factors which play a key role in plant response to water stress. As in other cereals, the DRF1 gene in Aegilops speltoides consists of four exons and three introns and undergoes alternative splicing. A processed pseudogene was also identified and compared with the sequence of an actual mRNA transcript, breaking new ground in the understanding of the complex regulation mechanism of this gene. The genetic diversity was evaluated by comparison of inter- and intra-species variation among some Aegilops and Triticeae, by considering both the whole gene and exon 4 sequences. The phylogenetic analyses were able to cluster the sequences in well-supported clades attributable to the genomes analysed. The overall results suggest that there is a high similarity between the B and S genome copies of the DRF1 gene but also features indicating that the two genomes have evolved independently
Variability and expression profile of the DRF1 gene in four cultivars of durum wheat and one triticale under moderate water stress conditions
No full textThe dehydration responsive element binding (DREB) proteins are important transcription factors that contribute to stress endurance in plants triggering the expression of a set of abiotic stress-related genes. A DREB2-related gene, previously referred to as dehydration responsive factor 1 (DRF1) was originally isolated and characterized in durum wheat. The aim of this study was to monitor the expression profiles of three alternatively spliced TdDRF1 transcripts during dehydration experiments and to evaluate the effects of genetic diversity on the molecular response, using experimental conditions reflecting as closely as possible water stress perceived by cereals in open field. To investigate the effect of moderate water stress conditions, time-course dehydration experiments were carried out under controlled conditions in the greenhouse on four durum wheat and one triticale genotypes. Differences were observed in molecular patterns, thus, suggesting a genotype dependency of the DRF1 gene expression in response to the stress induced. The biodiversity of the transcripts of the DRF1 gene was explored in order to assess the level of polymorphism and its possible effects on structure and function of putative proteins. A total of nine haplotypes were identified in the sequences cloned, seven of which encompassing polymorphisms in exon 4, including the region codifying for the DNA binding Apetala2 (AP2) domain. The 3D structural models of the AP2 domain were generated by homology modelling using the variability observed. The polymorphisms analysed did not significantly affect the structural arrangement of the DNA binding domains, thus resulting compatible with the putative functionality. © 2012 Springer-Verlag Berlin Heidelberg
'Phytoantibodies': a general vector for the expression of immunoglobulin domains in transgenic plants
No full textSequences encoding the immunoglobulin heavy-chain variable (VH) domains were engineered in a new general purpose vector to transform plants via Agrobacterium. The expression of an isolated VH domain (IVD) after introduction into the plant genome has been monitored by northern, western and immunohistochemical analysis. Immunoblotting showed that the polypeptide was stably expressed and accounted for up to 1% of the soluble protein fraction. It is therefore proposed that single immunoglobulin domains of suitable specificity expressed in plants may constitute an effective system to inhibit the activity of molecules involved in plant pathology or plant development
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
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