Lipids and lipid mixtures in boundary layers: From hydration lubrication to osteoarthritis

The hydration layer surrounding the phosphocholine headgroups of single-component phosphatidylcholine lipids, or of lipid-mixtures, assembled at an interface greatly modifies the interfacial properties and interactions. As water molecules within the hydration layer are held tightly by the headgroup but are nonetheless very fluid on shear, the boundary lipid layers, exposing the highly hydrated headgroup arrays, can provide efficient boundary lubrication when sliding against an opposing surface, at physiologically high contact pressures. In addition, any free lipids in the surrounding liquid can heal defects which may form during sliding on the boundary phosphatidylcholine layer. Similar boundary lipid layers contribute to the lubricating, pressure-bearing, and wear-protection functions of healthy articular joints. This review presents a survey of the relationship between the molecular composition of the interfacial complex and the lubrication behavior of the lipid-based boundary layers, which could be beneficial for designing boundary lubricants for intra-articular injection for the treatment of early osteoarthritis.     

Lipid imaging in the zebra finch brain with secondary ion mass spectrometry

Lipids have diverse functions in the nervous system, but the study of their anatomical distributions in the intact brain is rather difficult using conventional methodologies. Here we demonstrate the application of high resolution time-of-flight (ToF) secondary ion mass spectrometry (SIMS) to image various lipid components and cholesterol across an entire brain section prepared from an adult zebra finch (Taeniopygia guttata), with a spatial resolution of 2.3 μm, resulting in the formation of 11.5 megapixel chemical images. The zebra finch is a songbird in which specific neural and developmental functions have been ascribed to discrete “song control nuclei” of the forebrain. We have observed a relative increase of palmitic acid C16:0 and oleic acid C18:1 in song control nuclei versus the surrounding tissue, while phosphate (PO₃⁻), representative of phospholipids, was lower in these regions. Cholesterol was present at a high level only in the white matter of the optic tectum. More diffuse distributions were observed for stearic, arachidonic, linolenic, and palmitoleic acids. The presented results illustrate that SIMS imaging is a useful approach for assessing changes in lipid content during song circuit development and song learning.     

The Effect of Copper Salts on Bioactive Compounds and Ultrastructure of Wheat Plants

Abiotic stress agents, among them metal stress, can cause oxidative damage to plant cells. In defense, plants can increase the production of secondary metabolites in order to mitigate the harmful effects caused by them. The purpose of this work was to evaluate the effect of two types of copper salts (CuSO₄ and Cu(NO₃)₂), added in two different amounts in soil (150 mg/kg, respectively 300 mg/kg), on assimilating pigments, total polyphenols, antioxidant activity and the elemental composition of wheat. The obtained results were compared with those from control plants grown in the same conditions but without copper salts. The amount of assimilating pigments, total polyphenols, and antioxidant activity respectively increases or decreases in the plants treated with copper salts compared to the control depending on the stage of development of the plant. No significant damage induced in the leaves of the wheat plants treated with the selected salts was observed following the TEM analysis. In six-week-old plants it was observed by EDX analysis that the salts are transformed into nanoparticles. The bioactive compounds, elemental composition and their interaction is influenced by concentration of metal’s salt, type of salt and exposure period.     

二价阳离子诱导细胞膜融合的和频光谱研究（英文）

细胞膜融合是一种重要的基础生物学过程,细胞的很多生物学功能都涉及到细胞膜的融合.二价阳离子可以通过与带负电磷脂的结合诱导磷脂膜的融合,然而,其详细的分子学机制目前还不太清楚.本文应用表/界面敏感的和频振动光谱结合动态光散射实验研究了磷脂分子层对二价金属离子(如Ca²⁺和Mg²⁺)暴露的响应.动态光散射实验测量的粒度分布结果显示Ca²⁺可以诱导囊泡间融合,而Mg²⁺的介导却不能导致磷脂膜的融合.为了应用和频光谱研究磷脂分子不同基团对金属离子的响应,本文设计了十八烷基三氯硅烷自组装单分子层/磷脂单分子层组成的混合模型膜系统进行和频振动光谱实验.实验发现,相比于Mg²⁺,Ca²⁺与磷脂头部基团PO₂^-有更强烈地相互作用,会更容易诱导细胞膜融合.和频光谱实验还显示,虽然两种金属阳离子没有与磷脂中C=O基团直接连接.但是Ca²⁺/Mg²⁺-PO₂^-...     

Surfactants – Compounds for inactivation of SARS-CoV-2 and other enveloped viruses

We provide here a general view on the interactions of surfactants with viruses, with a particular emphasis on how such interactions can be controlled and employed for inhibiting the infectivity of enveloped viruses, including coronaviruses. The aim is to provide to interested scientists from different fields, including chemistry, physics, biochemistry, and medicine, an overview of the basic properties of surfactants and (corona)viruses, which are relevant to understanding the interactions between the two. Various types of interactions between surfactant and virus are important, and they act on different components of a virus such as the lipid envelope, membrane (envelope) proteins and nucleocapsid proteins. Accordingly, this cannot be a detailed account of all relevant aspects but instead a summary that bridges between the different disciplines. We describe concepts and cover a selection of the relevant literature as an incentive for diving deeper into the relevant material. Our focus is on more recent developments around the COVID-19 pandemic caused by SARS-CoV-2, applications of surfactants against the virus, and on the potential future use of surfactants for pandemic relief. We also cover the most important aspects of the historical development of using surfactants in combatting virus infections. We conclude that surfactants are already playing very important roles in various directions of defence against viruses, either directly, as in disinfection, or as carrier components of drug delivery systems for prophylaxis or treatment. By designing tailor-made surfactants, and consequently, advanced formulations, one can expect more and more effective use of surfactants, either directly as antiviral compounds or as part of more complex formulations.     

索氏桃花水母刺细胞超微结构研究

利用透射电镜对索氏桃花水母的粘性刺丝囊细胞与穿刺刺丝囊刺细胞的超微结构进行了研究．在粘性刺丝囊形成过程中观察到,刺丝内含物电子致密度由低到高逐渐增加,并产生小团分离,最后形成盘曲的刺丝．在穿刺刺丝囊细胞中,可见中心粒结构和较大的线粒体,刺丝局部可见微管构造,它整齐排列在盘曲的刺丝外侧,刺丝囊的排放可能受感觉细胞与神经细胞的共同调节,线粒体可为刺丝排放提供能量．     

Endoplasmatic reticulum shaping by generic mechanisms and protein-induced spontaneous curvature

The endoplasmatic reticulum (ER) comprises flattened vesicles (cisternae) with worm holes dubbed with ribosomes coexisting with a network of interconnected tubes which can extend to the cell periphery or even penetrate nerve axons. The coexisting topologies enclose a continuous luminal space. The complex ER topology is specifically controlled by a group of ER-shaping proteins often called reticulons (discovered by the group of Tom Rapoport [1]). They include atlastin, reticulon, REEP and the MT severing protein spastin. A generic ER shape controlling factor is the necessity to maximize the area-to-volume ratio of ER membranes in the highly crowded cytoplasmic space. I present a model of the ER-shaping function of the reticulons based on the Helfrich bending elasticity concept of soft shell shape changes. Common structural motifs of the reticulons are hydrophobic sequences forming wedge shaped hairpins which penetrate the lipid bilayer of the cell membranes. The wedge-like hydrophobic anchors can both induce the high curvature of the tubular ER fraction and ensure the preferred distribution of the reticulons along the tubules. Tubular junctions may be stabilized by the reticulons forming two forceps twisted by 90°. The ER extensions to the cell periphery and the axons are mediated by coupling of the tubes to the microtubules which is mediated by REEP and spastin. At the end I present a model of the tension driven homotype fusion of ER-membranes by atlastin, based on analogies to the SNARE–complexin–SNARE driven heterotype fusion process.     

Antenna morphology and sensilla ultrastructure of Tetrigus lewisi Candèze (Coleoptera: Elateridae)

We used scanning and transmission electron microscopy to study the typology, morphology, distributions, and ultrastructures of the antennal sensilla of Tetrigus lewisi Candèze, a predatory click beetle that feeds on longhorned beetles, such as, Monochamus alternatus (Coleoptera: Cerambycidae). We observed eight types of sensilla on the antennae, including sensilla chaetica (with three subtypes: ch.1, ch.2, ch.3), sensilla basiconica (subtypes: ba.1, ba.2, ba.3), sensilla trichodea (subtypes: tr.1, tr.2), as well as sensilla auricillica, sensilla coeloconica, sensilla campaniformia, sensilla styloconica and Böhm's bristles. Significant sexual dimorphism was found in the antenna morphology, as well as in the density of type 2 sensilla trichodea and type 1 sensilla basiconica. We observed thick cuticular walls on sensilla chaetica, sensilla trichodea and sensilla campaniformia; clear pore structures on sensilla trichodea, sensilla basiconica and sensilla auricillica; and double walls with spoke-channels on sensilla coeloconica. The chemoreception, mechanoreception and thermo-/hygro-reception functions were deduced from fine structures on the cuticular walls and the dendrites of the different sensilla types. We suggest that all these sensilla have important roles in the host location, mating and predatory behavior of T. lewisi.     

The synthesis and characterization of lipophilic peptide-based carriers for gene delivery

Lipophilic carriers have shown great potential in improving the delivery of gene therapeutics. We have synthesized positively charged peptide-based carriers including lipoamino acids. The carriers were shown to interact with DNA by performing isothermal titration calorimetry and particle size and zeta potential experiments. An exothermic reaction resulted from the titration of carrier into DNA. The particle sizes of the carrier/DNA complexes varied over the different charge ratios from 200-800 nm. The zeta potential was negative at a low charge ratio but positive when the amount of carrier was increased. The utilisation of lipophilic carriers is a promising approach to improve the bioavailability of gene delivery.