1,720,967 research outputs found
Footprint of domestication in the common bean (Phaseolus vulgaris L.) genome
No full textIl fagiolo comune (Phaseolus vulgaris L.) è una specie annuale diploide (2n = 2x = 22),
prevalentemente autocompatibile; è il più importante legume da granella per il consumo diretto. La specie è
caratterizzata da due principali pool genici, quello mesoamericano e quello andino, ed in ognuno dei due il
fagiolo ha subito una domesticazione indipendente. Molti studi hanno investigato la diversità molecolare e
fenotipica e la struttura della popolazione del fagiolo comune, ma non sono molte le informazioni riguardanti
la sua diversità nucleotidica. In questo lavoro, è stato studiato il processo di domesticazione in Mesoamerica
mediante il sequenziamento di 54 frammenti genici in un set di 47 accessioni di fagiolo, molte delle quali
provenenti dal Mesoamerica (39; sia genotipi selvatici che domesticati). Otto accessioni addizionali sono
state incluse come controlli: quattro di origine andina, due da popolazioni selvatiche del Nord Perù ed
Ecuador caratterizzate dalla faseolina di tipo I (proteina di riserva del seme), e un’accessione di P. coccineus
e di P. dumosus. Questo studio rappresenta il primo tentativo di approccio “bottom-up” per identificare loci
coinvolti nel processo di domesticazione di P. vulgaris, identificando tre geni come putativi target della
selezione artificiale durante la domesticazione in Mesoamerica. L’uso di dati nucleotidici ha permesso di
identificare chiaramente una riduzione di diversità genetica e un più esteso linkage disequilibrium nelle
forme domesticate rispetto alle selvatiche da imputare al bottleneck della domesticazione. La struttura della
popolazione, le analisi PCA, l’albero NJ e i network degli aplotipi hanno indicato un singolo evento di
domesticazione in Mesoamerica. Infine, un risultato del presente studio è stata l’individuazione di 825 SNPs.
Questi polimorfismi rappresentano uno strumento utile in diversi tipi di studi su P. vulgaris, come quelli di
tipo evoluzionistico, di genetica di popolazione o studi di associazione tra tratti agronomici importanti e
marker da usare nei programmi di incrocio.The common bean (Phaseolus vulgaris L.) is a diploid (2n = 2x = 22) annual species that is predominantly
self-pollinating, and it is the most important grain legume for direct human consumption. This species is
characterised by two major geographically distinct gene pools that predate its domestication, and where two
independent domestication events occurred: Mesoamerica and the Andes. Many studies have investigated the
molecular and phenotypic diversity and the population structure of the common bean, although little
information is available on the level and extent of its nucleotide diversity. Here, we focused on the
domestication process in Mesoamerica by sequencing 54 gene fragments from a set of 47 accessions of the
common bean, most of which were from Mesoamerica (39; as both wild and domesticated forms). Eight
additional accessions were included as controls: four from the Andes, two from northern Peru–Ecuador wild
populations that are characterised by phaseolin type I (a seed storage protein), and one each of Phaseolus
coccineus and Phaseolus dumosus accessions. This study is the first to use a bottom-up approach to identify
loci involved in the domestication process of P. vulgaris, and we have identified three outlier genes that
might have been the target of artificial selection during the domestication process in Mesoamerica. The use
of nucleotide data allowed the identification of a clear reduction in diversity and a higher level of linkage
disequilibrium in the domesticated forms, clearly due to the domestication bottleneck. Population structure,
principal component, neighbour-joining tree, and network haplotype analyses indicate the occurrence of a
single domestication event in Mesoamerica. Finally, an additional outcome of the present study is the
identification of 825 single nucleotide polymorphisms. These polymorphisms represent a useful tool for
different studies, such as evolutionary studies for Phaseolus species, population genetics studies, and
association studies between important agronomic traits and markers for use in breeding programmes
The splicing genes SmEa and SmEb regulate plant development during vegetative growth in poplar
No full textBackground: Spliceosomes are large evolutionary conserved ribonucleoprotein complexes containing at their core heptameric rings of Sm (or LSm) proteins and U-rich snRNAs. The role of Sm proteins in animal development is well established, and recent research has begun to link mutations in these genes to growth defects in plants. One of the most studied Sm genes is SmE1/PCP, mutants of which display a temperature-dependent phenotype in Arabidopsis thaliana. Results: This study provides a first glimpse into the function of a core splicing protein in the regulation of growth in a perennial species. Phylogenetic analysis identified two paralogous SmE genes in poplar, named SmEa and SmEb, that encode identical proteins and are orthologs of SmEs from Arabidopsis, as suggested by Y2H and in vivo experiments. CRISPR/Cas9 mutagenesis in hybrid aspen identified a role for SmEs in development in plants grown in an environment simulating seasonal photoperiod and temperature changes. Unlike in Arabidopsis, low temperatures had no or only a very minor effect on the development of sme mutants in aspen. Conclusions: We identified specific aspects of SmE in poplar, highlighting the importance of examining the physiological and evolutionary differences that define this gene family in woody compared to herbaceous plants
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
Editorial: CONSTANS – signal integration and development throughout the plant kingdom
No full textPeer reviewe
Miglioramento genetico ed ampliamento della base genetica di fagiolo e fagiolino per l'agricoltura biologica
No full textVariations 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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