1,720,973 research outputs found
Influence of the sebaceous gland density on the stratum corneum lipidome
Full text linkThe skin surface lipids (SSL) result from the blending of sebaceous and epidermal lipids, which derive from the sebaceous gland (SG) secretion and the permeability barrier of the stratum corneum (SC), respectively. In humans, the composition of the SSL is distinctive of the anatomical distribution of the SG. Thus, the abundance of sebum biomarkers is consistent with the density of the SG. Limited evidence on the influence that the SG exerts on the SC lipidome is available. We explored the differential amounts of sebaceous and epidermal lipids in areas at different SG density with lipidomics approaches. SC was sampled with adhesive patches from forearm, chest, and forehead of 10 healthy adults (8F, 2M) after mechanical removal of sebum with absorbing paper. Lipid extracts of SC were analysed by HPLC/(-)ESI-TOF-MS. In the untargeted approach, the naïve molecular features extraction algorithm was used to extract meaningful entities. Aligned and normalized data were evaluated by univariate and multivariate statistics. Quantitative analysis of free fatty acids (FFA) and cholesterol sulfate (CHS) was performed by targeted HPLC/(-)ESI-TOF-MS, whereas cholesterol and squalene were quantified by GC-MS. Untargeted approaches demonstrated that the relative abundance of numerous lipid species was distinctive of SC depending upon the different SG density. The discriminating species included FFA, CHS, and ceramides. Targeted analyses confirmed that sebaceous FFA and epidermal FFA were increased and decreased, respectively, in areas at high SG density. CHS and squalene, which are biomarkers of epidermal and sebaceous lipid matrices, respectively, were both significantly higher in areas at elevated SG density. Overall, results indicated that the SG secretion intervenes in shaping the lipid composition of the epidermal permeability barrier. © 2018, The Author(s)
Environmental stresses affect aflatoxin synthesis and conidiogenesis in a. flavus through sirtuin pathway involvement.
No full textAflatoxins are health hazardous secondary metabolites produced by the cosmopolitan fungus A. flavus. The ability of this fungus to exploit several substrates is also related to its psicrophylicity and enormous production of conidia. In relation to this, some ongoing climate changes favor plant susceptibility to the attack by this fungus with a consequent, dangerous, increase of aflatoxins into previously unexploited feed- and foodstuff.
In this study we analyze how some environmental stresses to which A. flavus may undergo also during host exploitation – namely, hypoxia, pH alteration, carbon starvation and oxidative stress – affect aflatoxin biosynthesis, fungal growth and conidiogenesis. By multiple analytical approaches (mass spectrometry, transcriptional analysis, fluorimetric assays) we check the trend of specific molecular pathways related to metabolism reprogramming in consequence of environmental signals. Results indicate that sirtuins– a class of deacetylase enzymes – could represent the interface between signal transduction pathways and transcriptional reprogramming into A. flavus.Nevertheless the results obtained, further study to clearly define the role of sirtuins in shaping transcriptome in A. flavus are required
FAD8, lip and osmotin are cold-acclimation genes in Olea europaea L.
No full textOlive tree is an evergreen species of economic value lacking winter dormancy and showing low tolerance to
frost. This low tolerance limits its cultivation in cold regions, where, by contrast, oil quality is improved by
an enrichment in unsaturated fatty acids, i.e., linoleic (C18:2) and linolenic (C18:3) acids, produced by the
activity of specific fatty acid desaturases (FADs). Cold-resistant genotypes have been empirically selected
from centuries however the genetic network controlling cold-tolerance in olive tree is still unknown.
Transient changes in cytosolic calcium are involved in sensing the cold stress and in activating cold
acclimation in numerous plants, including olive tree (1-2). A role for the PR-5 protein Osmotin (OeOSM) in
olive tree cold acclimation has been suggested, possibly as transfer protein to the cell wall of cutinsomes,
containing unsaturated fatty acid-derived compounds (3, 4). The expression of genes coding for specific
FADs, i.e. OeFAD2.2 and OeFAD7, necessary for C18:2 and C18:3 production, respectively, has been
demonstrated to be positively related to olive tree drupe cold-response. However, the expression of both
genes normally occurs during oil biogenesis, and increases under cold-stress independently of the
acclimation capabilities of the genotypes, suggesting that these genes are unrelated with cold acclimation (2).
By contrast, in Arabidopsis thaliana and other plants, FAD8, isoform of FAD7, is specifically activated by
cold (5). Moreover, FAD8 expression in maize is activated concomitantly with the beta-Zip LIP transcription
factor mlip19 (6), and members of LIP19-family are activated by calcium transients (7). The research aim
was to identify transcripts of an OeLIP gene in leaves and drupes of two genotypes, one incapable and the
other capable of cold acclimation, by cold-stresses applied before, during and after the possible
natural/artificial acquisition of cold acclimation, investigating, in parallel, the changes in OeOSM and
OeFAD8 expression, the immuno-localization of OeOSM, and by detecting the levels of C18:3-compounds
deriving by OeFAD8 activity. Preliminarly, leaves and drupes belonging to cv. Moraiolo and cv. Canino
were exposed to cold shocks of different duration and intensity at the same developmental stages, and the
cold response evaluated in their protoplasts in terms of presence/absence of cytosolic calcium transients, for
determining their differences in cold acclimation under all cold conditions. Both genotypes were cold
sensitive at the beginning of the oil biogenesis in the drupe (WAF 10), however Canino was able to acquire
artificial acclimation at this WAF. Only cv. Moraiolo showed calcium rises, i.e. remained cold-sensitive at
the end of oil biogenesis (WAF 19) in leaves and drupes, and continued to be sensitive even in full winter
(WAF 26), showing its total inability to cold acclimate, differently from the other genotype.
An OeLIP gene was isolated and characterized, and its changes monitored by q-PCR in both leaves and
drupes under the same cold-shocks applied for monitoring cytosolic calcium changes. OeLIP was activated
by cold-induced calcium signalling. Its expression increased with cold, but became stable only in Canino.
OeFAD8 transcription was also induced by calcium signalling, and changed in parallel with that of OeLIP.
The production of C18:3, and related compounds, by OeFAD8 activity, increased in Canino in concomitance
with acclimation. Also OeOSM was activated by calcium signalling, and its transcripts were high and stable
during acclimation acquisition and maintenance by Canino drupes and leaves. Moreover, both organs
showed increased cutinisation of the outer cell walls of epicarp and adaxial epidermis, respectively, with this
event strongly increasing in Canino, and positively coupling with an increased immunolocalization of
OeOSM in the cuticle. All together, results demonstrate that OeFAD8, OeLIP and OeOSM jointly control
cold-acclimation in Olea europaea drupes and leaves
Use of lipidomics to investigate sebum dysfunction in juvenile acne
No full textAcne is a multifactorial skin disorder frequently observed during adolescence with different grades of severity. Multiple factors centering on sebum secretion are implicated in acne pathogenesis. Despite the recognized role of sebum, its compositional complexity and limited analytical approaches have hampered investigation of alterations specifically associated with acne. To examine the profi les of lipid distribution in acne sebum, 61 adolescents (29 males and 32 females) were enrolled in this study. Seventeen subjects presented no apparent clinical signs of acne. The 44 affected individuals were clinically classifi ed as mild (13 individuals), moderate (19 individuals), and severe (12 individuals) acne. Sebum was sampled from the forehead with Sebutape TM adhesive patches. Profi les of neutral lipids were acquired with rapid-resolution reversed-phase/HPLC-TOF/MS in positive ion mode. Univariate and multivariate statistical analyses led to the identification of lipid species with significantly different levels between healthy and acne sebum. The majority of differentiating lipid species were diacylglycerols (DGs), followed by fatty acyls, sterols, and prenols. Overall, the data indicated an association between the clinical grading of acne and sebaceous lipid fingerprints and highlighted DGs as more abundant in sebum from adolescents affected with acne
Quantitative profiling of oxylipins through comprehensive LC-MS/MS analysis of Fusarium verticillioides and maize kernels
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
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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