170,400 research outputs found
Use of TD-GC–TOF-MS to assess volatile composition during post-harvest storage in seven accessions of rocket salad (Eruca sativa). BELL L, SPADAFORA D.N. contributed equally to the work
No full textAn important step in breeding for nutritionally enhanced varieties is determining the effects of the postharvest
supply chain on phytochemicals and the changes in VOCs produced over time. TD-GC–TOF-MS
was used and a technique for the extraction of VOCs from the headspace using portable tubes is
described. Forty-two compounds were detected; 39 were identified by comparison to NIST libraries.
Thirty-five compounds had not been previously reported in Eruca sativa. Seven accessions were assessed
for changes in headspace VOCs over 7 days. Relative amounts of VOCs across 3 time points were significantly
different – isothiocyanate-containing molecules being abundant on ‘Day 0’. Each accession
showed differences in proportions/types of volatiles produced on each day. PCA revealed a separation
of VOC profiles according to the day of sampling. Changes in VOC profiles over time could provide a tool
for assessment of shelf life
Retrotransposon-Encoded Reverse Transcriptase in the Genesis, Progression and Cellular Plasticity of Human Cancer
No full textLINE-1 (Long Interspersed Nuclear Elements) and HERVs (Human Endogenous Retroviruses) are two families of autonomously replicating retrotransposons that together account for about 28% of the human genome. Genes harbored within LINE-1 and HERV retrotransposons, particularly those encoding the reverse transcriptase (RT) enzyme, are generally expressed at low levels in differentiated cells, but their expression is upregulated in transformed cells and embryonic tissues. Here we discuss a recently discovered RT-dependent mechanism that operates in tumorigenesis and reversibly modulates phenotypic and functional variations associated with tumor progression. Downregulation of active LINE-1 elements drastically reduces the tumorigenic potential of cancer cells, paralleled by reduced proliferation and increased differentiation. Pharmacological RT inhibitors (e.g., nevirapine and efavirenz) exert similar effects on tumorigenic cell lines, both in culture and in animal models. The HERV-K family play a distinct complementary role in stress-dependent transition of melanoma cells from an adherent, non-aggressive, to a non-adherent, highly malignant, growth phenotype. In synthesis, the retrotransposon-encoded RT is increasingly emerging as a key regulator of tumor progression and a promising target in a novel anti-cancer therapy
L'arco di "Druso". Procedure per un rilevamento integrato
No full textQuesto lavoro presenta un primo risultato di una ricerca, svolta grazie alla collaborazione di studiosi nelle discipline della rappresentazione, del rilevamento e dell’archeologia, riguardante il cosiddetto Arco di Druso. Questo manufatto archeologico, risulta essere particolarmente complesso, riguardo la datazione ed interpretazione, in quanto presenta diverse strutture sovrapposte e stratificate nel tempo: una prima originaria (costruita in epoca pre-imperiale), relativa ad un arco di trionfo a tre fornici, una seconda riutilizzata come arco di un acquedotto (III sec. d. C.,) e una terza decorata da alcuni elementi architettonici (1800 ca.). Il lavoro di analisi dell’Arco di Druso, basato sulle necessarie indagini storiografiche, iconografiche e documentarie, ha avuto come principale obiettivo quello di fornire una descrizione grafica del manufatto che potesse essere, da una parte, quanto più accurata possibile dal punto di vista metrico-dimensionale e, dall’altra, rivelatrice dei diversi aspetti dell’edificio.
A questo scopo è stata sperimentata una metodologia di rilevamento che utilizza vari sistemi di misurazione: di tipo strumentale, topografico e GPS, fotogrammetrico e tradizionale diretto, che vanno a integrarsi tra di loro, in modo da restituire un modello tridimensionale informatizzato di riferimento per tutte le fasi successive di restituzione. Particolare importanza è stata data al rilevamento diretto, soprattutto nello studio degli elementi di dettaglio delle modanature che ha messo in evidenza alcuni aspetti indicatori delle diverse fasi costruttive, in particolare l’inserimento di elementi di restauro negli elementi dell’ordine architettonico del fronte Sud.
Il testo si divide in: una primo paragrafo introduttivo sullo stato di fatto, su una puntuale analisi iconografica, storica e documentaria dei recenti rilievi (D. Maestri), un secondo riguardo Il rilevamento integrato, secondo la descrizione delle diverse procedure di analisi, misurazione e restituzione grafica (M. Canciani), una terzo, riferito al rilevamento diretto ed alla elaborazione dei grafici di restituzione alla grande scala (G. Spadafora).
Perturbation of cytokinin and ethylene-signalling pathways explain the strong rooting phenotype exhibited by Arabidopsis expressing the Schizosaccharomyces pombe mitotic inducer, cdc25
No full textBackground
Entry into mitosis is regulated by cyclin dependent kinases that in turn are phosphoregulated. In most eukaryotes, phosphoregulation is through WEE1 kinase and CDC25 phosphatase. In higher plants a homologous CDC25 gene is unconfirmed and hence the mitotic inducer Schizosaccharomyces pombe (Sp) cdc25 has been used as a tool in transgenic plants to probe cell cycle function. Expression of Spcdc25 in tobacco BY-2 cells accelerates entry into mitosis and depletes cytokinins; in whole plants it stimulates lateral root production. Here we show, for the first time, that alterations to cytokinin and ethylene signaling explain the rooting phenotype elicited by Spcdc25 expression in Arabidopsis.
Results
Expressing Spcdc25 in Arabidopsis results in increased formation of lateral and adventitious roots, a reduction of primary root width and more isodiametric cells in the root apical meristem (RAM) compared with wild type. Furthermore it stimulates root morphogenesis from hypocotyls when cultured on two way grids of increasing auxin and cytokinin concentrations. Microarray analysis of seedling roots expressing Spcdc25 reveals that expression of 167 genes is changed by > 2-fold. As well as genes related to stress responses and defence, these include 19 genes related to transcriptional regulation and signaling. Amongst these was the up-regulation of genes associated with ethylene synthesis and signaling. Seedlings expressing Spcdc25 produced 2-fold more ethylene than WT and exhibited a significant reduction in hypocotyl length both in darkness or when exposed to 10 ppm ethylene. Furthermore in Spcdc25 expressing plants, the cytokinin receptor AHK3 was down-regulated, and endogenous levels of iPA were reduced whereas endogeous IAA concentrations in the roots increased.
Conclusions
We suggest that the reduction in root width and change to a more isodiametric cell phenotype in the RAM in Spcdc25 expressing plants is a response to ethylene over-production. The increased rooting phenotype in Spcdc25 expressing plants is due to an increase in the ratio of endogenous auxin to cytokinin that is known to stimulate an increased rate of lateral root production. Overall, our data reveal important cross talk between cell division and plant growth regulators leading to developmental changes
Conformity or Nonconformity in Multinationality? Performance Implications for the Italian Ceramic Tile Manufacturers
No full textTo date international management studies have found mixed results on the relationship between multinationality and performance. We address the multinationality–performance relationship by exploring the concept of conformity in multinationality, which expresses the extent to which a firm’s multinationality resembles the multinationality of its peers at a particular point in time. Our results show that, ceteris paribus, the best performing firms are those with high levels of conformity in multinationality to the strategic group peers as well as those with high levels of conformity to the market leader. Hypotheses are tested with data on the conformity in multinationality of 61 Italian ceramic tile manufacturers in the 2005–2009 time period
Monitoring leaf senescence in rocket leaf under temperature stress using physiological and biochemical parameters
No full textReduction in photosynthetic activity, increase of respiration and cell membrane degradation are senescence physiological processes that greatly induce quality losses in leafy vegetables. These effects are enhanced by the occurrence of abiotic stresses such as variations of storage temperature.
In order to study the senescence progress at low and high metabolic state, rocket leaves (Diplotaxis tenuifolia L.) were collected and stored at 4°C and 20°C for 14 and 4 days respectively. Chlorophyll a fluorescence was measured to evaluate the senescence by monitoring the leaf health status. The maximum quantum efficiency of PSII (Fv/Fm) declined progressively at both storage temperatures. The performance index, as overall evaluation of leaf functionality, was 2.6 soon after harvest and declined faster at higher temperature. The dissipation energy expressed for reaction center (DIo/RC) or per cross section (DIo/CS) increased progressively with storage time. Means of lipid peroxidation and sugars content determination were evaluated. Reduction in sugars level and increase in lipid peroxidation were observed early at 20°C and lately at 4°C.
We investigate also the influence of storage temperature and time on head space Volatile Organic Compounds composition. We were able to identify the major volatile compounds associated with rocket aroma and show significant changes in the overall VOC profile during storage. We were also able to separate the VOC profiles from the different temperatures indicating that VOCs may be useful markers as indicators of the effects of these parameters on quality.
Our results showed that the storage temperature has a direct effect on the quality and shelf life of rocket by influencing the occurrence of senescence associated processes. Moreover, photosynthetic indexes can be considered as good non-destructive markers of senescence during storage
A role for endogenous reverse transcriptase in tumorigenesis and as a target in differentiating cancer therapy
No full textAn unexpected result emerging from completion of the genome sequencing project is that a large portion of mammalian genomes is constituted by retrotransposons. A large body of published data supports the conclusion that retrotransposons are biologically active elements and indicates that retrotransposition is an ongoing process in mammalian genomes. Retroelements can act as insertional mutagens altering the coding integrity of genes and, recently, have been found to also affect the expression of cellular genes at the epigenetic level: in this light, they are a potential threat in that these events can trigger the onset of several pathologies including cancer. Retroelement genes, and particularly the gene coding for reverse transcriptase (RT), are typically expressed at high levels in transformed cells and tumors. In recent work, we have found that drug-mediated inhibition of the endogenous RT activity, or silencing of expression of active retrotransposons of the LINE-1 family by RNA interference, down-regulate cell growth and induce the activation of differentiating functions in several cancer cell lines. Moreover, the inhibition of endogenous RT activity in vivo antagonizes the growth of human tumors in animal models. In this review, we discuss newly emerging concepts on the role of retrotransposons and suggest that an abnormally high level of the RT activity that they encode may contribute to the loss of control in the proliferation and differentiation programs typical of transformed cells. In this light, RT-coding elements may be regarded as promising targets in the development of novel, differentiation-inducing approaches to cancer therapy. © 2005 Wiley-Liss, Inc
LINE-1 retrotransposon copies are amplified during murine early embryo development
No full textTwo large families of retrotransposons, that is, LINE-1 (Long Interspersed Nuclear Elements-1) and endogenous retroviruses, encode reverse transcriptase (RT) proteins in vertebrates. We previously showed that mouse preimplantation embryos are endowed with an endogenous, functional RT activity. Inhibiting that activity by microinjecting antisense oligonucleotides against a highly active LINE-1 family member in mouse oocytes blocked developmental progression between the two- and four-blastomere stages, indicating that LINE-1-encoded RT activity is strictly required at this critical transition in early development. Here we show that incubation of mouse zygotes with 5'-bromodeoxyuridine (BrdU) yields massive incorporation of this nucleoside analogue in newly synthesized DNA; surprisingly, a significant incorporation still occurs in both zygotic pronuclei in the presence of aphidicolin, a specific inhibitor of DNA replication. This aphidicolin-resistant BrdU incorporation is quantitatively abolished when embryos are simultaneously exposed to abacavir, a nucleoside RT inhibitor, indicating its retrotranscription-dependent nature. Moreover, quantitative PCR analysis revealed a burst of new synthesis of LINE-1 copies at the zygote- and two-cell embryo stages. These findings support the conclusion that RT-dependent amplification of LINE-1 retrotransposons is a distinctive feature of early embryonic genomes. Its physiological involvement in preimplantation murine development is discussed
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