1,720,967 research outputs found
Preliminary fire blight resistance evaluation of pear genotypes as support for breeding.
No full textAn important factor that significantly limits the cultivation of pear trees in Europe is fire blight caused by the Gram-negative bacterium Erwinia amylovora. The selection of resistant or tolerant varieties and rootstocks is one of the main objectives of breeding programs worldwide in order to control and limit the disease spread. The final aim of this study is to identify candidate resistance genes and to develop new PCR-based molecular markers for the marker-assisted breeding of pear varieties. To this aim a pear population obtained from the “Abate Fétel” x “Old Home” cross is under testing for fire blight resistance in greenhouse. A total of 135 sibling genotypes and the two parental genotypes were bud-grafted on the commercial rootstock “Fox 11” in order to obtain shoots to be inoculated with a virulent E. amylovora strain. The strain to be used was selected through an experimental inoculation in “Abate Fétel” and “Conference” plants, among Italian strains isolated from pear in different times and in different regions, cross confirmed with infections on pear flowers. The strain OMP-1077/7.94, isolated from pear in 1994 during an epidemic outbreak has been used as reference strain in both the biological characterization and in the virulence test. Molecular analyses as SPET (Single Primer Enrichment Technology) genotyping analysis was conducted on the pear population and genetic maps were constructed for each parental genotype. According to genotypic and phenotypic data, a QTL analysis will be performed in order to localize E. amylovora resistance genes in the pear genome
The effects of dietary supplementation with high doses of vitamin E and C on the quality traits of chicken semen
No full text
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
Preliminary identification of QTLs associated with fire blight resistance in pear
No full textErwinia amylovora, the causal agent of fire blight in pome fruits, is still one of the main threats of pear cultivation in Italy. The disease severely affects pear production especially when the weather conditions are favorable to the bacterium spreading. In pear germplasm different levels of fire blight susceptibility/resistance are described. The cultivar Old Home is known for its fire blight resistance and has been used in breeding. A mapping population (‘Abbé Fétel’ × ‘Old Home’) was studied to detect genomic regions associated with possible resistance to fire blight. A progeny of 133 individuals was phenotyped by inoculation via cut-leaf method, of actively growing shoots of potted grafted plants in greenhouse conditions with the E. amylovora isolate FP621 from pear. This isolate was selected as the most virulent among some old and recent Italian isolates through pathogenicity tests on pear potted plants. High resolution SNP-based genetic maps of the parental lines were produced via the SPET technology. The QTL analysis conducted with the phenotypic and genomic data allowed a preliminary identification of two QTLs for E. amylovora resistance in the ‘Old Home’ map. The obtained results are currently used to identify candidate genes and for developing a suite of molecular markers for DNA-informed breeding
Evaluation of mast cells in calf and heifer uteri
No full textThe aims of the present study were to determine the main distribution patterns of mast cells residing in the uterine walls of calves and heifers, and to obtain reference values for these cells on order to assist in the evaluation of endometrial biopsies in cows. Following the results of the present trial, the reference values proposed for the resident mast cells are (mast cells/ x 400): 11 for stratum compactum alone, 7 as an average of stratum compactum+ st. spongiosum, and 5 as an average of stratum compactum+ st. spongiosum+ st. musculare+ st. vasculare
A six-amino acid deletion in basic fibroblast growth factor dissociates its mitogenic activity from its plasminogen activator-inducing capacity.
No full textA recombinant deletion mutant of the 155-amino acid form of human basic fibroblast growth factor (bFGF), lacking amino acid residues 27-32 (Lys-Asp-Pro-Lys-Arg-Leu), was expressed in Escherichia coli and purified to homogeneity by heparin-Sepharose affinity chromatography. When maintained in the presence of an equimolar concentration of soluble heparin, the bFGF mutant (M1-bFGF) is as potent as bFGF in stimulating cell proliferation in normal and transformed fetal bovine aortic endothelial cells, in adult bovine aortic endothelial cells, and in NIH 3T3 fibroblasts. However, under the same experimental conditions, M1-bFGF is at least 100 times less efficient than bFGF in stimulating plasminogen activator (PA) production in endothelial cells, as assayed by chromogenic PA assay, SDS/PAGE zymography, and Northern blot analysis of urokinase-type PA mRNA. In the presence of heparin, M1-bFGF binds to bFGF plasma membrane receptors present on endothelial cells in a manner undistinguishable from bFGF. It also induces the same tyrosine phosphorylation pattern when added to NIH 3T3 cells. The data suggest that the PA-inducing activity of bFGF may depend upon a functional domain that differs from those involved in the mitogenic activity of the growth factor and that the binding of bFGF to its plasma membrane receptor may not be sufficient to induce urokinase-type PA production in endothelial cells
Biochemical bases of the interaction of the human basic fibroblast growth factor with glycosaminoglycans: new insights from trypsin digestion studies
No full textHeparins from bovine mucosa and lung, and chemically modified
heparins were assayed for their capacity to: (i) protect human
recombinant basic fibroblast growth factor (bFGF) from tryptic
cleavage; (ii) prevent 1251-bFGF binding to heparan sulphate
proteoglycans present in the extracellular matrix and on the cell
surface of fetal bovine aortic endothelial GM 7373 cell cultures;
(iii) affect 1251-bFGF binding to high-affinity tyrosine kinase
FGF receptors present on the cell membrane of GM 7373 cells;
(iv) inhibit the mitogenic activity exerted by bFGF in the same
cells. The results demonstrate thatthe potency shown by mucosal
heparins in the different assays is a direct function of size, verylow-
molecular-mass heparin (2.0 kDa) being significantly less
effective on a molar basis than unfractionated heparin (13.6 kDa).
Increased flexibility of the backbone structure, as observed in
reduced/oxidized heparins of different size, does not affect the
capacity of the polysaccharide to interact with bFGF. In contrast,
selective 2-O-desulphation, but not 6-O-desulphation, drastically
reduced the capacity of heparin to protect bFGF from proteolytic
cleavage, to affect its interaction with low- and high-affinity sites,
and to inhibit its mitogenic activity. Two preparations of bovine
lung heparin, differing in molecular mass, were as effective as
mucosal heparin in the bFGF-tryptic-digestion assay and the
endothelial-cell proteoglycan-binding assay, but they were highly
inefficient at inhibiting the capacity of bFGF to interact with its
tyrosine kinase receptors. Bovine lung heparins were also less
effective than mucosal heparin as bFGF antagonists in GM
7373-cell-proliferation assays. N-Desulphated/N-acetylated
bovine lung heparin retained only a significant capacity to
protect bFGF from tryptic cleavage. The results demonstrate
that different chemical features of the heparin molecule, including
decrease in molecular mass, selective desulphation, disaccharide
composition and clustering, affect differently the capacity of the
glycosaminoglycan to interact with bFGF and to influence its
biological behaviour in different assays in vitro and in endothelial
cell cultures. Our findings should aid the design of synthetic
oligosaccharides aimed at improving the. bioavailability of bFGF
when administered in vivo as a therapeutic agent
- …
