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[en] Although phosphoenolpyruvate carboxylases (PEPCs) are reported to be involved in fatty acid accumulation, nitrogen assimilation, and salt and drought stresses, knowledge regarding PEPC gene functions is still limited, particularly in peanuts (Arachis hypogaea L.). In this study, the antisense expression of the peanut PEPC isoform 1 (AhPEPC1) gene increased the lipid content by 5.7%–10.3%. This indicated that AhPEPC1 might be related to plant lipid accumulation. The transgenic plants underwent more root elongation than the wild-type under salinity stress. Additionally, the specific down regulation of the AhPEPC1 gene improved the salt tolerance in peanuts. This is the first report on the role of PEPC in lipid accumulation and salt tolerance in peanuts.
[en] Membrane tubes are important functional elements for living cells. Experiments have found that membrane tubes can be extracted from giant lipid vesicles by groups of kinesin. How these motors cooperate in extracting the membrane tube is a very important issue but still unclear so far. In this paper, we propose a cooperation mechanism called two-track-dumbbell model, in which kinesin is regarded as a dumbbell with an end (tail domain) tethered on the Quid-like membrane and the other end (head domain) stepping on the microtubule. Taking account of the elasticity of kinesin molecule and the excluded volume effect of both the head domain and the tail domain of kinesin, which are not considered in previous models, we simulate the growth process of the membrane tube pulled by kinesin motors. Our results indicate that in the case of strong or moderate exclusion of motor tails, the average number of motors pulling the tube can be as high as 9 and thus motors moving along a single microtubule protofilament can generate enough force to extract membrane tubes from vesicles. This result is different from previous studies and may be tested by future experiments. (interdisciplinary physics and related areas of science and technology)
[en] Coronaviruses (CoVs) can cause life-threatening respiratory diseases. Their infectious entry requires viral spike (S) proteins, which attach to cell receptors, undergo proteolytic cleavage, and then refold in a process that catalyzes virus-cell membrane fusion. Fusion-inhibiting peptides bind to S proteins, interfere with refolding, and prevent infection. Here we conjugated fusion-inhibiting peptides to various lipids, expecting this to secure peptides onto cell membranes and thereby increase antiviral potencies. Cholesterol or palmitate adducts increased antiviral potencies up to 1000-fold. Antiviral effects were evident after S proteolytic cleavage, implying that lipid conjugates affixed the peptides at sites of protease-triggered fusion activation. Unlike lipid-free peptides, the lipopeptides suppressed CoV S protein-directed virus entry taking place within endosomes. Cell imaging revealed intracellular peptide aggregates, consistent with their endocytosis into compartments where CoV entry takes place. These findings suggest that lipidations localize antiviral peptides to protease-rich sites of CoV fusion, thereby protecting cells from diverse CoVs. - Graphical abstract: Early and late CoV entry is depicted as virus-cell fusion at cell surfaces and endosomes, respectively. Scissors represent virus-activating proteases. The HR2 peptides are in green, with lipid-free peptides as monomers (middle panel) and lipopeptides as micellar aggregates (right panel). - Highlights: • Lipidation increases antiviral activities of CoV fusion-inhibiting peptides. • Fusion-inhibiting peptides target proteolytically-triggered CoV spike proteins. • Lipidated peptides suppress CoVs that are occluded within endosomes before cytosolic entry.
[en] The use oleogels (defined as edible oils entrapped in a three-dimensional network employing a self-assembled structuring agent) has recently been proposed to replace saturated fat or trans-fats in foods. In this work the effects of different cellulose derivative mixtures (Avicel, ethyl cellulose and a-cellulose) on lipid stability, glass transition temperature and the texture of soybean oil oleogels were determined by employing a mixture design approach. Avicel affected lipid stability, increasing the oxidative rancidity and peroxide values of oleogels. Oleogels with higher proportions of Avicel also presented higher transition temperatures. A higher percent of ethyl cellulose and a-cellulose in the oleogel mixture resulted in a more stable system with lower oil rancidity and lower glass transition temperatures. In addition, Avicel resulted in a softer and less tacky texture, an important characteristic to consider for food applications.
[es]Recientemente, ha sido propuesto el uso de oleogeles (definido como aceites comestibles atrapados en una red tridimensional que ocupa un agente estructurante de auto-ensamblado) como substituto de grasa saturada o grasas trans en alimentos. En este trabajo el efecto de mezclas de diferentes derivados celulósicos (Avicel, etil celulosa y a-celulosa) sobre la estabilidad de lípidos, temperaturas de transición térmica y textura de oleogeles de aceite de soja fueron determinados utilizando un diseño de mezclas. Avicel afectó la estabilidad de lípidos, aumentando la rancidez oxidativa y valores de peróxido en los oleogeles. Oleogeles con mayores proporciones de Avicel también presentaron temperaturas de transición térmica más altas. porcentajes más altos de etil celulosa y a-celulosa resultaron en un sistema más estable con menor rancidez oxidativa y menores temperaturas de transición térmica. Sin embargo, Avicel resultó en una textura más suave y menos pegajosa, una característica importante a considerar para su aplicación en alimentos.
[en] Highlights: • Biodiesel can be produced via catalytic and non-catalytic processes. • Mass production of biodiesel with continuous-flow reactors is reviewed. • Continuous process assisted with ultrasound, microwave, supercritical method. • New techniques developed to improve mass transfer and biodiesel conversion. • Continuous-flow conversion of microalgal oil is intensively reviewed. - Abstract: Biodiesel has been receiving considerable attention as an alternative energy source over the last decade. Conventionally, biodiesel is produced by transesterification of lipid and alcohol, with or without the aid of catalysts. Due to the presence of multiple phases during the catalytic reaction, the mass transfer between reactants and catalysts, as well as the type of catalyst used are the two major factors that should be considered during the design of the reactor applied for the targeted conversion. Most efforts in this area focused on the selection of effective catalysts (e.g., homogeneous catalysts, heterogeneous catalysts, enzymes) for biodiesel conversion via transesterification. The tests are regularly conducted on batch mode and the optimization of the operating conditions was done. However, to scale up the biodiesel production, many researchers utilized continuous-flow regime to continuously convert lipids to biodiesel with preferable process design to solve the problems encountered during continuous operation. This review is aimed at providing the knowledge and updated information on recent advances of the continuous-flow biodiesel production technology. This article presents and critically discusses the advantages and limitations of using catalyzed and non-catalyzed transesterification in conventional continuous-flow reactors and those assisted by supercritical conditions, membrane reactors, ultrasound, microwave, and other special techniques. Several newly developed processes, such as oscillatory flow reactor (OFR), microchannel reactors, laminar flow reactor-separator, liquid-liquid film reactor, which could minimize mass transfer resistance and improve biodiesel conversion are also presented. Finally, updates on conversion technologies for lipids from oleaginous microalgae (potential third-generation oil feedstock) to biodiesel and reviews on commercial continuous-flow biodiesel conversion technologies are provided.
[en] Constitutively activated oncogenic signaling via genetic mutations such as in the EGFR/PI3K/Akt and Ras/RAF/MEK pathways has been recognized as a major driver for tumorigenesis in most cancers. Recent insights into tumor metabolism have further revealed that oncogenic signaling pathways directly promote metabolic reprogramming to upregulate biosynthesis of lipids, carbohydrates, protein, DNA and RNA, leading to enhanced growth of human tumors. Therefore, targeting cell metabolism has become a novel direction for drug development in oncology. In malignant gliomas, metabolism pathways of glucose, glutamine and lipid are significantly reprogrammed. Moreover, molecular mechanisms causing these metabolic changes are just starting to be unraveled. In this review, we will summarize recent studies revealing critical gene alterations that lead to metabolic changes in malignant gliomas, and also discuss promising therapeutic strategies via targeting the key players in metabolic regulation
[en] Unlike Non-classical membrane bound proteins, Chloride Intracellular Ion Channel Protein 1 (CLIC1) challenges our current understanding in relation to the process whereby such proteins insert into membrane. CLIC1 exists as either a membrane bound form or a soluble form, it has an unusual ability to exist in two stable conformations in its soluble form, this phenomenon has been described as a 'metamorphic ability'. A large degree of rearrangement of the amino terminus of the CLIC1 during its transition between the two stable conformations, arises as a result of oxidation. CLIC1 insertion is influenced by many factors, including the phospholipid composition and the ratio of cholesterol in the lipid membrane. We have been led to believe cholesterol plays is a major part in enabling CLIC1 insertion into membranes. This study involves varying the phospholipid : cholesterol ratio in the model membrane.