Lipids and oils derived from plant and algal photosynthesis constitute much of human daily caloric intake and provide the basis for high-energy bioproducts, chemical feedstocks for countless ...applications, and even fossil fuels over geological time scales. Sustainable production of high-energy compounds from plants is essential to preserving fossil fuel sources and ensuring the well-being of future generations. As a result of progress in basic research on plant and algal lipid metabolism, in combination with advances in synthetic biology, we can now tailor plant lipids for desirable biological, physical, and chemical properties. We highlight recent advances in plant lipid translational biology and discuss untapped areas of research that might expand the application of plant lipids.
Imaging plant metabolism in situ Horn, Patrick J; Chapman, Kent D
Journal of experimental botany,
03/2024, Letnik:
75, Številka:
6
Journal Article
Recenzirano
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Abstract
Mass spectrometry imaging (MSI) has emerged as an invaluable analytical technique for investigating the spatial distribution of molecules within biological systems. In the realm of plant ...science, MSI is increasingly employed to explore metabolic processes across a wide array of plant tissues, including those in leaves, fruits, stems, roots, and seeds, spanning various plant systems such as model species, staple and energy crops, and medicinal plants. By generating spatial maps of metabolites, MSI has elucidated the distribution patterns of diverse metabolites and phytochemicals, encompassing lipids, carbohydrates, amino acids, organic acids, phenolics, terpenes, alkaloids, vitamins, pigments, and others, thereby providing insights into their metabolic pathways and functional roles. In this review, we present recent MSI studies that demonstrate the advances made in visualizing the plant spatial metabolome. Moreover, we emphasize the technical progress that enhances the identification and interpretation of spatial metabolite maps. Within a mere decade since the inception of plant MSI studies, this robust technology is poised to continue as a vital tool for tackling complex challenges in plant metabolism.
The objective of this review is to provide a timely update on how mass spectrometry imaging is used to visualize plant metabolism in situ .
We analyze the impact of contractionary monetary policy through increases in reserve requirements on bank lending. We compare the lending behavior of banks that were subject to the requirement ...increases in 1936–37, Federal Reserve member banks, to a group of banks that were not subject to the reserve increase, Federal Reserve nonmember banks. After implementing the difference-in-difference estimators, we find that the increases in reserve requirements did not create financing constraints for member banks and lead them to reduce lending. Therefore, the actions of the Federal Reserve concerning the required reserve ratios cannot be blamed for instigating the economic downturn of 1937–38.
Cysteines (Cys) are chemically reactive amino acids containing sulfur that play diverse roles in plant biology. Recent proteomics investigations in Arabidopsis thaliana have revealed the presence of ...thiol post-translational modifications (PTMs) on several Cys residues. These PTMs are presumed to impact protein structure and function, yet mechanistic data regarding the specific Cys susceptible to modification and their biochemical relevance remains limited. To help address these limitations, we have conducted a wide-ranging analysis by integrating published datasets encompassing PTM proteomics (comparing S-sulfenylation, persulfidation, S-nitrosylation, and S-acylation), genomics, and protein structures, with a specific focus on proteins involved in plant lipid metabolism. The prevalence and distribution of modified Cys residues across all analyzed proteins is diverse and multifaceted. Nevertheless, by combining an evaluation of sequence conservation across 100+ plant genomes with AlphaFold-generated protein structures and physicochemical predictions, we have unveiled structural propensities associated with Cys modifications. Furthermore, we have identified discernible patterns in lipid biochemical pathways enriched with Cys PTMs, notably involving beta-oxidation, jasmonic acid biosynthesis, fatty acid biosynthesis, and wax biosynthesis. These collective findings provide valuable insights for future investigations targeting the mechanistic foundations of Cys modifications and the regulation of modified proteins in lipid metabolism and other metabolic pathways.
Lipins are phosphatidate phosphatases that generate diacylglycerol (DAG). In this study, we report that yeast lipin, Pah1p, controls the formation of cytosolic lipid droplets. Disruption of PAH1 ...resulted in a 63% decrease in droplet number, although total neutral lipid levels did not change. This was accompanied by an accumulation of neutral lipids in the endoplasmic reticulum (ER). The droplet biogenesis defect was not a result of alterations in neutral lipid ratios. No droplets were visible in the absence of both PAH1 and steryl acyltransferases when grown in glucose medium, even though the strain produces as much triacylglycerol as wild type. The requirement of PAH1 for normal droplet formation can be bypassed by a knockout of DGK1. Nem1p, the activator of Pah1p, localizes to a single punctum per cell on the ER that is usually next to a droplet, suggesting that it is a site of droplet assembly. Overall, this study provides strong evidence that DAG generated by Pah1p is important for droplet biogenesis.
Hereditary angioedema is a rare genetic disorder characterized by acute, intermittent, and potentially life-threatening attacks of edema of the skin and mucosa. We evaluated ecallantide, a newly ...developed recombinant plasma kallikrein inhibitor, for the treatment of acute attacks of angioedema.
In this double-blind, placebo-controlled trial, patients with hereditary angioedema presenting with an acute attack were randomly assigned, in a 1:1 ratio, to receive subcutaneous ecallantide, at a dose of 30 mg, or placebo. Two measures of patient-reported outcomes were used to assess the response: treatment outcome scores, which range from +100 (designated in the protocol as significant improvement in symptoms) to -100 (significant worsening of symptoms), and the change from baseline in the mean symptom complex severity score, which range from +2 (representing a change from mild symptoms at baseline to severe symptoms after) to -3 (representing a change from severe symptoms at baseline to no symptoms after). The primary end point was the treatment outcome score 4 hours after study-drug administration. Secondary end points included the change from baseline in the mean symptom complex severity score at 4 hours and the time to significant improvement.
A total of 71 of the 72 patients completed the trial. The median treatment outcome score at 4 hours was 50.0 in the ecallantide group and 0.0 in the placebo group (interquartile range IQR, 0.0 to 100.0 in both groups; P=0.004). The median change in the mean symptom complex severity score at 4 hours was -1.00 (IQR, -1.50 to 0.00) with ecallantide, versus -0.50 (IQR, -1.00 to 0.00) with placebo (P=0.01). The estimated time to significant improvement was 165 minutes with ecallantide versus more than 240 minutes with placebo (P=0.14). There were no deaths, treatment-related serious adverse events, or withdrawals owing to adverse events.
Four hours after administration of ecallantide or placebo for acute attacks of angioedema in patients with hereditary angioedema, patient-reported treatment outcome scores and mean symptom complex severity scores were significantly better with ecallantide than with placebo. (Funded by Dyax; ClinicalTrials.gov number, NCT00262080.)
Lipid droplets in plants (also known as oil bodies, lipid bodies, or oleosomes) are well characterized in seeds, and oleosins, the major proteins associated with their surface, were shown to be ...important for stabilizing lipid droplets during seed desiccation and rehydration. However, lipid droplets occur in essentially all plant cell types, many of which may not require oleosin-mediated stabilization. The proteins associated with the surface of nonseed lipid droplets, which are likely to influence the formation, stability, and turnover of this compartment, remain to be elucidated. Here, we have combined lipidomic, proteomic, and transcriptomic studies of avocado (Persea americana) mesocarp to identify two new lipid droplet-associated proteins, which we named LDAP1 and LDAP2. These proteins are highly similar to each other and also to the small rubber particle proteins that accumulate in rubber-producing plants. An Arabidopsis (Arabidopsis thaliana) homolog to LDAP1 and LDAP2, At3g05500, was localized to the surface of lipid droplets after transient expression in tobacco (Nicotiana tabacum) cells that were induced to accumulate triacylglycerols. We propose that small rubber particle protein-like proteins are involved in the general process of binding and perhaps the stabilization of lipid-rich particles in the cytosol of plant cells and that the avocado and Arabidopsis protein members reveal a new aspect of the cellular machinery that is involved in the packaging of triacylglycerols in plant tissues.
The emergence of ‘omics’ technologies (i.e. genomics, proteomics, metabolomics, etc.) have revealed new avenues for exploring plant metabolism through data-rich experimentation and integration of ...complementary methodologies. Over the past decade, the lipidomics field has benefited from advances in instrumentation, especially mass spectrometry (MS)-based approaches that are well-suited for detailed lipid analysis. The broad classification of what constitutes a lipid lends itself to a structurally diverse range of molecules that contribute to a variety of biological processes in plants including membrane structure and transport, primary and secondary metabolism, abiotic and biotic stress tolerances, extracellular and intracellular signaling, and energy-rich storage of carbon. Progress in these research areas has been advanced in part through approaches analyzing chemical compositions of lipids in extracts from cells, tissues and/or whole organisms (e.g. shotgun lipidomics), and through visualization approaches primarily through microscopy-based methodologies (e.g. fluorescence, bright field, electron microscopy, etc.). While these techniques on their own provide rich biochemical and biological information, coordinated analyses of the complexity of lipid composition with the localization of these lipids at a high spatial resolution will help to develop a new level of understanding of lipid metabolism within the context of tissue/cellular compartmentation. This review will elaborate on recent advances of one such approach – mass spectrometry imaging (MSI) – that integrates in situ visualization with chemical-based lipidomics. We will illustrate, with an emphasis on oilseed lipid metabolism, how MS imaging can provide new insights and questions related to the spatial compartmentation of lipid metabolism in plants. Further it will be apparent that this MS imaging approach has broad application in plant metabolic research well beyond that of triacylglycerol biosynthesis in oilseeds.
Eravacycline is a novel fluorocycline, highly active against Gram-positive and Gram-negative pathogens in vitro, including those with tetracycline and multidrug resistance. This phase 2, randomized, ...double-blind study was conducted to evaluate the efficacy and safety of two dose regimens of eravacycline compared with ertapenem in adult hospitalized patients with complicated intra-abdominal infections (cIAIs). Patients with confirmed cIAI requiring surgical or percutaneous intervention and antibacterial therapy were randomized (2:2:1) to receive eravacycline at 1.5 mg/kg of body weight every 24 h (q24h), eravacycline at 1.0 mg/kg every 12 h (q12h), or ertapenem at 1 g (q24h) for a minimum of 4 days and a maximum of 14 days. The primary efficacy endpoint was the clinical response in microbiologically evaluable (ME) patients at the test-of-cure (TOC) visit 10 to 14 days after the last dose of study drug therapy. Overall, 53 patients received eravacycline at 1.5 mg/kg q24h, 56 received eravacycline at 1.0 mg/kg q12h, and 30 received ertapenem. For the ME population, the clinical success rate at the TOC visit was 92.9% (39/42) in the group receiving eravacycline at 1.5 mg/kg q24h, 100% (41/41) in the group receiving eravacycline at 1.0 mg/kg q12h, and 92.3% (24/26) in the ertapenem group. The incidences of treatment-emergent adverse events were 35.8%, 28.6%, and 26.7%, respectively. Incidence rates of nausea and vomiting were low in both eravacycline groups. Both dose regimens of eravacycline were as efficacious as the comparator, ertapenem, in patients with cIAI and were well tolerated. These results support the continued development of eravacycline for the treatment of serious infections, including those caused by drug-resistant Gram-negative pathogens. (This study has been registered at ClinicalTrials.gov under registration no. NCT01265784.).
High biomass crops have recently attracted significant attention as an alternative platform for the renewable production of high energy storage lipids such as triacylglycerol (TAG). While TAG ...typically accumulates in seeds as storage compounds fuelling subsequent germination, levels in vegetative tissues are generally low. Here, we report the accumulation of more than 15% TAG (17.7% total lipids) by dry weight in Nicotiana tabacum (tobacco) leaves by the co‐expression of three genes involved in different aspects of TAG production without severely impacting plant development. These yields far exceed the levels found in wild‐type leaf tissue as well as previously reported engineered TAG yields in vegetative tissues of Arabidopsis thaliana and N. tabacum. When translated to a high biomass crop, the current levels would translate to an oil yield per hectare that exceeds those of most cultivated oilseed crops. Confocal fluorescence microscopy and mass spectrometry imaging confirmed the accumulation of TAG within leaf mesophyll cells. In addition, we explored the applicability of several existing oil‐processing methods using fresh leaf tissue. Our results demonstrate the technical feasibility of a vegetative plant oil production platform and provide for a step change in the bioenergy landscape, opening new prospects for sustainable food, high energy forage, biofuel and biomaterial applications.
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