Biological membranes, primarily composed of lipids, envelop each living cell. The intricate composition and organization of membrane lipids, including the variety of fatty acids they encompass, serve a dynamic role in sustaining cellular structural integrity and functionality. Typically, modifications in lipid composition coincide with consequential alterations in universally significant signaling pathways. Exploring the various fatty acids, which serve as the foundational building blocks of membrane lipids, provides crucial insights into the underlying mechanisms governing a myriad of cellular processes, such as membrane fluidity, protein trafficking, signal transduction, intercellular communication, and the etiology of certain metabolic disorders. Furthermore, comprehending how alterations in the lipid composition, especially concerning the fatty acid profile, either contribute to or prevent the onset of pathological conditions stands as a compelling area of research. Hence, this review aims to meticulously introduce the intricacies of membrane lipids and their constituent fatty acids in a healthy organism, thereby illuminating their remarkable diversity and profound influence on cellular function. Furthermore, this review aspires to highlight some potential therapeutic targets for various pathological conditions that may be ameliorated through dietary fatty acid supplements. The initial section of this review expounds on the eukaryotic biomembranes and their complex lipids. Subsequent sections provide insights into the synthesis, membrane incorporation, and distribution of fatty acids across various fractions of membrane lipids. The last section highlights the functional significance of membrane-associated fatty acids and their innate capacity to shape the various cellular physiological responses.

The most unique biochemical characteristic of the eye lens fiber cell plasma membrane is its extremely high cholesterol content, the need for which is still unclear. It is evident, however, that the disturbance of Chol homeostasis may result in damages associated with cataracts. Electron paramagnetic resonance methods allow discrimination of two types of lipid domains in model membranes overloaded with Chol, namely, phospholipid-cholesterol domains and pure Chol bilayer domains. These domains are also detected in human lens lipid membranes prepared from the total lipids extracted from lens cortices and nuclei of donors from different age groups. Independent of the age-related changes in phospholipid composition, the physical properties of phospholipid-Chol domains remain the same for all age groups and are practically identical for cortical and nuclear membranes. The presence of Chol bilayer domains in these membranes provides a buffering capacity for cholesterol concentration in the surrounding phospholipid-Chol domains, keeping it at a constant saturating level and thus keeping the physical properties of the membrane consistent with and independent of changes in phospholipid composition. It seems that the presence of Chol bilayer domains plays an integral role in the regulation of cholesterol-dependent processes in fiber cell plasm membranes and in the maintenance of fiber cell membrane homeostasis.

Biosurfactant rhmnolipids have been applied in many fields, especially in environmental bioremediation. According to previous researches, many research groups have studied the influence of rhamnolipids on microorganism characteristics and/or its application in composting. In this review, the effects of rhamnolipids on the cell surface properties of microorganisms was discussed firstly, such as cell surface hydrophobicity (CSH), electrical, surface compounds, etc. Moreover, the deeper mechanisms were also discussed, such as the effects of rhamnolipids on the structural characteristics and functional characteristics of the cell membrane, and the effects of rhamnolipids on the related enzymes and genes. Additionally, the application of rhamnolipids in composting was discussed, which is an important way for pollutant biodegradation and resource reutilization. It is believed that rhamnolipids will play more and more important role in composting.

Lipid composition determines membrane properties, and cholesterol plays a major role in this determination as it regulates membrane fluidity and permeability, as well as induces the formation of coexisting phases and domains in the membrane. Biological membranes display a very diverse lipid composition, the lateral organization of which plays a crucial role in regulating a variety of membrane functions. We hypothesize that, during biological evolution, membranes with a particular cholesterol content were selected to perform certain functions in the cells of eukaryotic organisms. In this review, we discuss the major membrane properties induced by cholesterol, and their relationship to certain membrane functions.

The primary cilium is an extraordinary organelle. For many years, it had the full attention of only a few dedicated scientists fascinated by its uniqueness. Unexpectedly, after decades of obscurity, it has moved very quickly into the limelight with the increasing evidence of its central role in the many genetic variations that lead to what are now known as ciliopathies. These studies implicated unique biological functions of the primary cilium, which are not completely straightforward. In parallel, and initially completely unrelated to the ciliopathies, the primary cilium was characterized functionally as an organelle that makes cells more susceptible to changes in fluid flow. Thus the primary cilium was suggested to function as a flow-sensing device. This characterization has been substantiated for many epithelial cell types over the years. Nevertheless, part of the central mechanism of signal transduction has not been explained, largely because of the substantial technical challenges of working with this delicate organelle. The current review considers the recent advances that allow us to fill some of the holes in the model of signal transduction in cilium-mediated responses to fluid flow and to pursue the physiological implications of this peculiar organelle.

Free radicals generated within subcellular compartments damage macromolecules which lead to severe structural changes and functional alterations of cellular organelles. A manifestation of free radical injury to biological membranes is the process of lipid peroxidation, an autooxidative chain reaction in which polyunsaturated fatty acids in the membrane are the substrate. There is considerable evidence that damage to polyunsaturated fatty acids tends to reduce membrane fluidity. However, adequate levels of fluidity are essential for the proper functioning of biological membranes. Thus, there is considerable interest in antioxidant molecules which are able to stabilize membranes because of their protective effects against lipid peroxidation. Melatonin is an indoleamine that modulates a wide variety of endocrine, neural and immune functions. Over the last two decades, intensive research has proven this molecule, as well as its metabolites, to possess substantial antioxidant activity. In addition to their ability to scavenge several reactive oxygen and nitrogen species, melatonin increases the activity of the glutathione redox enzymes, that is, glutathione peroxidase and reductase, as well as other antioxidant enzymes. These beneficial effects of melatonin are more significant because of its small molecular size and its amphipathic behaviour, which facilitates ease of melatonin penetration into every subcellular compartment. In the present work, we review the current information related to the beneficial effects of melatonin in maintaining the fluidity of biological membranes against free radical attack, and further, we discuss its implications for ageing and disease.

This mini-review is addressed to the question how the membranous environment may affect traffic of receptors and signalling from membrane-anchored receptors on the outside of cells to transducers and targets on the inside. Signal transduction by membrane-anchored receptors to the interior of the cell and eventually to the genome is a central issue in cellular regulation. In this context the role of membrane fluidity and of the cytoskeleton in restricting the mobility of proteins are discussed and the evidence for a structural order in membranes which could limit the mobility of proteins is scrutinised.

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There is evidence that free radicals are involved in membrane pathology, and may play a role in schizophrenia. Free radicals are reactive chemical species generated during normal metabolic processes, and, in excess, can damage lipids, proteins, and DNA. Regions of high oxygen consumption, lipid content, and transition metals are at particular risk. Hence, neuronal membranes are uniquely vulnerable to radical-mediated damage. Elaborate antioxidant defense systems exist to protect against oxidative stress. In schizophrenia there is evidence for dysregulation of free radical metabolism, as detected by abnormal activities of critical antioxidant enzymes and other indices of lipid peroxidation in plasma, red blood cells, and cerebrospinal fluid. Such abnormalities have been associated with tardive dyskinesia, negative symptoms, neurological signs, poor premorbid function, and CT scan abnormalities. Studies to date have generally been exploratory. Further elucidation of the role of free radicals and antioxidants in schizophrenia and its treatment will require systematic investigation.

Anaesthesia is a drug-induced reversible perturbation of neuronal activity. Since a wide variety of structurally unrelated substances are capable of producing this phenomenon, it has been generally accepted that anaesthetics produce their effects through non-specific hydrophobic interactions. Results of recent studies in whole animal and cellular (membrane) preparations demonstrate that a unitary theory of action does not exist. Anaesthetics can produce a spectrum of activity in the central nervous system, and different agents produce different patterns of activity. At the cellular and membrane level, differential effects have been observed, structural dependent differences occur and optical isomers display very different activities. The perturbation (fluidity change) of membrane components does not appear to be uniform for all anaesthetics. It is concluded that anaesthetics are selective agents, and produce their effects at multiple sites and through a variety of mechanisms.