159 research outputs found
Rocket salad aroma is affected by sampling method, species and degree of leaf damage
No full textRocket salad is a valuable commercial product often sold as a bagged ready to eat salad. Two
different species from the Brassicaceae family are sold as rocket salad: Diplotaxis tenuifolia and Eruca
sativa. Both are aromatic, and previous studies have shown that their aroma is composed of a complex
mixture of volatile organic compounds (VOCs) from several different chemical families. Of particular
interest are isothiocyanates that are generated from the metabolism of glucosinolates produced by
Brassicaceae species. Both types of rocket salad have a limited shelf-life and there has been interest in
assessing whether analysis of VOCs could be used to help set ‘use by dates’ assess quality changes, and
report on issues within the supply chain. However, different methods have been used to sample and
analyse the VOC profiles. Here we compare the profiles from D. tenuifolia using two VOC sampling
methods (solid phase microextraction, SPME) and sampling onto thermal desorption (TD) tubes. We
also compare the VOC profiles sampled onto TD tubes from both species from leaves subjected to different
levels of damage: intact, chopped and blended. We find that both the method of VOC sampling
and the level of leaf damage have important effects on the VOC profile. In the comparison, fewer VOCs
are detected when sampling with SPME compared to TD tubes. Overall, 41 different VOCs are detected
in the leaf damage experiment but many fewer are detected in intact leaves. While the two rocket
species are distinct based on the VOC profile of chopped leaves, they are not discriminated by VOC
profiles of blended or intact leaves. When species are considered separately VOC profile discriminates
level of damage. Very few isothiocyanates are detected in intact or chopped leaves, presumably due to
the requirement for leaf damage to activate their production from glucosinolates. To conclude, level of
leaf damage will strongly influence VOC profiles from rocket leaves, and medium damage seems to
elicit the most discriminatory profiles
Analysis of Apple Flavours: The Use of Volatile Organic Compounds to Address Cultivar Differences and the Correlation between Consumer Appreciation and Aroma Profiling
No full textIn the selection of apple (Malus domestica Borkh) fruits, consumers predominantly use visual and organoleptic responses, such as aroma and texture, as quality/preference markers. Previous studies profiling the sensory properties and aroma profiles of apple varieties have provided a lexicon describing important attributes within the modalities of aroma, texture, and flavour. The range of volatile organic compounds (VOCs) produced by four apple cultivars was assessed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). To facilitate automated dynamic headspace extraction of the VOCs from bulk samples, a small multichamber thermal extraction system was used. Forty compounds were detected and putatively identified by mass spectral comparison with NIST libraries. Eight compounds were not previously identified in apples. Permutational multivariate analysis of variance (PerMANOVA) and canonical analysis of principal coordinates (CAP) done on the whole volatile organic compound profiles show separation of the four cultivars. The use of random forest classification enabled the determination of a minimum set of fifteen potential VOC markers that successfully differentiate the cultivars under study. Trends across samples, VOCs, and sensory evaluation are revealed. The association between 4-hexen-1-ol acetate with texture/consistency, and crispiness, and correlation of 2-methylbut-2-en-1-yl acetate with juiciness and acidity is shown for the first time. These sensory correlations indicate that the compounds determined by this experiment could be used as objective markers for the consumer appreciation of fresh apples, enabling the optimum conditions for processing and storage of individual cultivars to be identified without recourse to expensive sensory panels in every case. Such tests could also be used as part of routine quality control by the producer and retailer, reducing costs and eliminating waste due to batches of inferior product
Perturbation of cytokinin and ethylene-signalling pathways explain the strong rooting phenotype exhibited by Arabidopsis expressing the Schizosaccharomyces pombe mitotic inducer, cdc25
Get PDFBackground
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
Molecular mechanisms underlying potential pathogen resistance in cannabis sativa
Get PDFCannabis (Cannabis sativa L.) is one of the earliest cultivated crops, valued for producing a broad spectrum of compounds used in medicinal products and being a source of food and fibre. Despite the availability of its genome sequences, few studies explore the molecular mechanisms involved in pathogen defense, and the underlying biological pathways are poorly defined in places. Here, we provide an overview of Cannabis defence responses against common pathogens, such as Golovinomyces spp., Fusarium spp., Botrytis cinerea and Pythium spp. For each of these pathogens, after a summary of their characteristics and symptoms, we explore studies identifying genes involved in Cannabis resistance mechanisms. Many studies focus on the potential involvement of disease-resistance genes, while others refer to other plants however whose results may be of use for Cannabis research. Omics investigations allowing the identification of candidate defence genes are highlighted, and genome editing approaches to generate resistant Cannabis species based on CRISPR/Cas9 technology are discussed. According to the emerging results, a potential defence model including both immune and defence mechanisms in Cannabis plant–pathogen interactions is finally proposed. To our knowledge, this is the first review of the molecular mechanisms underlying pathogen resistance in Cannabis
Multi-omics approaches to study molecular mechanisms in Cannabis sativa
Get PDFCannabis (Cannabis sativa L.), also known as hemp, is one of the oldest cultivated crops, grown for both its use in textile and cordage production, and its unique chemical properties. However, due to the legislation regulating cannabis cultivation, it is not a well characterized crop, especially regarding molecular and genetic pathways. Only recently have regulations begun to ease enough to allow more widespread cannabis research, which, coupled with the availability of cannabis genome sequences, is fuelling the interest of the scientific community. In this review, we provide a summary of cannabis molecular resources focusing on the most recent and relevant genomics, transcriptomics and metabolomics approaches and investigations. Multi-omics methods are discussed, with this combined approach being a powerful tool to identify correlations between biological processes and metabolic pathways across diverse omics layers, and to better elucidate the relationships between cannabis sub-species. The correlations between genotypes and phenotypes, as well as novel metabolites with therapeutic potential are also explored in the context of cannabis breeding programs. However, further studies are needed to fully elucidate the complex metabolomic matrix of this crop. For this reason, some key points for future research activities are discussed, relying on multi-omics approaches
Multi-probe in situ hybridization to whole mount Arabidopsis seedlings
Get PDFIn situ RNA-RNA hybridization (ISH) is a molecular method for localization of gene transcripts at the cellular level and is widely used to provide spatial and temporal information regarding gene expression. However, standard protocols are complex and laborious to implement, restricting analysis to one or a few genes at any one time, each one observed on separate ISH preparations. Multi-probe whole-mount in situ hybridization is a powerful technique to compare the expression patterns of two or more genes simultaneously in the same tissue or organ. We describe for the first time in plants, the detection of three different mRNAs in a single fixed whole mount Arabidopsis seedling. A combination of bright fluorescent secondary antibodies was used for the detection of riboprobes differentially labeled by digoxigenin, biotin and fluorescein. The 3-D detection of each of the multiple fluorescent hybridization signals or in combination was obtained through confocal laser-scanning microscopy. The reliability of the method was tested in the root, using the PINFORMED (PIN) genes with non-overlapping temporal and spatial expression patterns. In the shoot, a class-I KNOTTED -like homeobox gene from Arabidopsis (KNAT1) with expression restricted to the shoot apical meristem was used in combination with ELONGATOR3 (ELO3)gene. In addition, the expression patterns of ELONGATOR complex gene (ELO2, ELO3) and HIS TONE MONOUBIOUITINATION1 (HUB1)genes were analyzed in both shoot and root and a partial overlapping was observed. The whole procedure takes only 6 days
Short-Term Post-Harvest Stress that Affects Profiles of Volatile Organic Compounds and Gene Expression in Rocket Salad During Early Post-Harvest Senescence
Get PDFOnce harvested, leaves undergo a process of senescence which shares some features with developmental senescence. These include changes in gene expression, metabolites, and loss of photosynthetic capacity. Of particular interest in fresh produce are changes in nutrient content and the aroma, which is dependent on the profile of volatile organic compounds (VOCs). Leafy salads are subjected to multiple stresses during and shortly after harvest, including mechanical damage, storage or transport under different temperature regimes, and low light. These are thought to impact on later shelf life performance by altering the progress of post-harvest senescence. Short term stresses in the first 24 h after harvest were simulated in wild rocket (Diplotaxis tenuifolia). These included dark (ambient temperature), dark and wounding (ambient temperature), and storage at 4 °C in darkness. The effects of stresses were monitored immediately afterwards and after one week of storage at 10 °C. Expression changes in two NAC transcription factors (orthologues of ANAC059 and ANAC019), and a gene involved in isothiocyanate production (thiocyanate methyltransferase, TMT) were evident immediately after stress treatments with some expression changes persisting following storage. Vitamin C loss and microbial growth on leaves were also affected by stress treatments. VOC profiles were differentially affected by stress treatments and the storage period. Overall, short term post-harvest stresses affected multiple aspects of rocket leaf senescence during chilled storage even after a week. However, different stress combinations elicited different responses
TRANSNATIONALISM, HOME AND IDENTITY: PERSONAL ESSAYS
Get PDFTRANSNATIONALISM, HOME AND IDENTITY: PERSONAL ESSAYSNatasha Garrett, PhD. University of Pittsburgh, 2011Through a collection of personal essays, this dissertation examines transnationalism as a contemporary mode of migration. The essays draw from my personal and professional experiences, as well as academic and literary sources, to create a collection that addresses significant aspects of the transnational experience, such as issues of identity, language, space/place and family, and explores the ways in which transnationalism as a postmodern phenomenon has transformed the perspective on those categories. The essay "Identifying Transnationalism and Transnational Identity," introduces the problem of identity for transnationals, both in the literature and in my personal life. The essay also examines how transnationals negotiate national/ethic and cultural identity. "Essay as Inquiry" is a discussion on the research method and a rationale for using the essay as a mode of inquiry when studying transnationalism. "International Students and Identity" suggests that the concept of transnationalism could be utilized to better illustrate and understand the experiences of international students in the United States. "Transnationalism and the Concept of Home" discusses the ways in which transnationals conceptualize space/place. In "Translating the Translator: Language, Poetry and Identity," the author draws from her experiences as a poetry translator to investigate issues of language and identity. Translation becomes a metaphor for understanding my own existence across two cultures. "Transnational Families" focuses on the changing family dynamics and the intra-generational relationships among transnational family members. The final essay, "Global Souls: Pico Iyer, Gogol Bordello and the Art of Academic Travel," discusses transnationalism as a source of global worldview and creative power
Comparison of volatile organic compounds, quality, and nutritional parameters from local Italian and international apple cultivars
Get PDFApple cultivars ‘Annurca’ and ‘Limoncella’ are grown locally in the Campania region of Italy and are valued for their distinctive flavour and characteristics, including a high content of nutritionally important bioactive compounds. However, apples are typically stored chilled for several months before consumption, so it is important to assess if the valuable characteristics are still present after postharvest storage. Here, we compare the quality, nutritional parameters, and aroma of these two cultivars with two widely grown international cultivars, ‘Golden Delicious’ and ‘Fuji’, after 60 days of storage. The aroma profiles of all four apples were analysed using thermal desorption and gas chromatography–time-of-flight mass spectrometry. We show that the local cultivars are distinct from the international cultivars in their bioactive compound content and their antioxidant activity. ‘Limoncella’ shows high sugar content, which may be acting as a cryoprotectant during storage, and high total phenolics in the flesh, which is of nutritional interest. We identified 104 volatile organic compounds (VOCs) and showed that the overall aroma profile is distinct for each cultivar, containing 11 published odorant compounds. The ‘Annurca’ profile is uniquely low in esters. Seven VOCs retain good discrimination across the four cultivars and, together with the quality and nutritional data, separate the two local cultivars from the international cultivars by hierarchical clustering. Overall, the data emphasize the unique characteristics of the two local cultivars and their value
A Multivariate Surface-Based Analysis of the Putamen in Premature Newborns: Regional Differences within the Ventral Striatum
Get PDFMany children born preterm exhibit frontal executive dysfunction, behavioral problems including attentional deficit/hyperactivity disorder and attention related learning disabilities. Anomalies in regional specificity of cortico-striato-thalamo-cortical circuits may underlie deficits in these disorders. Nonspecific volumetric deficits of striatal structures have been documented in these subjects, but little is known about surface deformation in these structures. For the first time, here we found regional surface morphological differences in the preterm neonatal ventral striatum. We performed regional group comparisons of the surface anatomy of the striatum (putamen and globus pallidus) between 17 preterm and 19 term-born neonates at term-equivalent age. We reconstructed striatal surfaces from manually segmented brain magnetic resonance images and analyzed them using our in-house conformal mapping program. All surfaces were registered to a template with a new surface fluid registration method. Vertex-based statistical comparisons between the two groups were performed via four methods: univariate and multivariate tensor-based morphometry, the commonly used medial axis distance, and a combination of the last two statistics. We found statistically significant differences in regional morphology between the two groups that are consistent across statistics, but more extensive for multivariate measures. Differences were localized to the ventral aspect of the striatum. In particular, we found abnormalities in the preterm anterior/inferior putamen, which is interconnected with the medial orbital/prefrontal cortex and the midline thalamic nuclei including the medial dorsal nucleus and pulvinar. These findings support the hypothesis that the ventral striatum is vulnerable, within the cortico-stiato-thalamo-cortical neural circuitry, which may underlie the risk for long-term development of frontal executive dysfunction, attention deficit hyperactivity disorder and attention-related learning disabilities in preterm neonates. © 2013 Shi et al
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