Polyunsaturated-fatty-acids have different physiological effects depending on the number and position of a double bond exists within the representative molecule, and the difference of acyl-chain length. According to the anti-obesity effects of polyunsaturated-fatty-acids, there are many researches with conjugated-fatty-acids (particularly conjugated-linoleic-acid) and n-3 polyunsaturated-fatty-acids (particularly eicosapentaenoic-acid, docosahexaenoic-acid, or fish oil which contains these fatty acids), which are conducted about the anti-obesity potentials and the mechanisms, possible effects on energy expenditure, lipid metabolism and so on, in cells, animals, and humans. In this review, we focus on conjugated-fatty-acids and n-3 polyunsaturated-fatty-acids in anti-obesity effects, and summarize of the potential of efficacy and possible mechanisms with recent reports.

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Arachidonic acid is an essential fatty acid, and is one of the major fatty acids in the brain, as well as docosahexaenoic acid. Arachidonic acid is contained in breast milk, and is important for the infant nutrition to be used for the infant formula. Arachidonic acid-supplementation improved the age-related impairment of learning performance in rats, and then was revealed to improve the cognitive function (event-related potentials) and the learning behavior in a neuropsychological assessment in aged humans. The related mechanisms are going to be found out, such as the preservation of hippocampal neuron membrane fluidity and the enhancement of the postnatal neurogenesis. The nutritional importance is also beginning to be clarified. Further studies are expected to reveal the importance of arachidonic acid-supplementation.

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Arachidonic acid, retinol and taurine are known to the cat : felis catus of the genuine flesh-eating animal as nutrient necessity. The required nature of the arachidonic acid depends on deficit of Δ⁶-desaturase. Therefore arachidonic acid cannot metabolize even if cat take in linoleic acid. Because the required nature of the retinol (vitamin A) deletes dioxygenase in the bowels, cat cannot resolve β-carotene into retinol. Because cat do not have an enzyme composing taurine, it is necessary to take in the taurine which there is only to animal protein. It mean that EPA and DHA cannot metabolize even if the deficit of Δ⁶-desaturase takes in the linolenic acid of the n-3 fatty acid. It is necessary to take in the mammalian meat which contains them because it cannot metabolize even if the cat of the genuine flesh-eating animal takes in linoleic acid and the linolenic acid of the plant to get arachidonic acid, EPA and DHA. The fish contains arachidonic acid, retinol, and taurine other than EPA and DHA. The photoreceptor of the retina of the cat which a thing looks like in darkness, DHA, retinol and taurine are that is to say necessary for construction and the maintenance of the photoreceptor. The writer suggests a hypothesis that “the cat eats a fish when it cannot take in meat” from the above-mentioned reason.

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Metabolic control and inter-organelle transport of phospholipids are essential events for membrane biogenesis in eukaryotes. The synthesis of the phospholipid phosphatidylserine (PS) in eukaryotes occurs in the endoplasmic reticulum (ER) and a subdomain of this organelle known as the mitochondria-associated membrane (MAM). In cultured mammalian cells, the PS synthesis is inhibited by exogenous PS, and this feedback control occurs not through regulation of expression of PS synthase genes, but through inhibition of PS synthases by PS. Meanwhile PS synthesized in ER/MAM is transported to various organelles including the plasma membranes, mitochondria, and Golgi. A significant body of data suggests that the inter-organelle transport of PS occurs at zones of contact between donor and acceptor membranes. Recent studies have identified some of the lipids and proteins that participate inthe PS transport from ER/MAM to mitochondria or Golgi. In this review, I describe the current understanding of the regulation of PS biosynthesis in mammalian cells and the transport of PS from ER/MAM to mitochondria or Golgi in mammalian and yeast cells.

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Throughout the life of multi-cellular organisms, cells unnecessary or harmful to our body emerge. Such 'unwanted' cells need to be promptly and selectively removed for tissue homeostasis to be maintained. These cells are mostly induced to undergo physiologic cell death, i.e. apoptosis, and become susceptible to phagocytosis. Membrane phospholipids play important roles in the phagocytosis of apoptotic cells, serving as an earmark for apoptotic cells and a regulator of a signaling pathway for phagocytosis. In this article, we will describe the mechanisms and consequences of the phospholipid-mediated phagocytosis of apoptotic cells.

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Novel functions of glycolipids are emerging. In this review, anti-tumor and immuno-regulatory actions of glycolipids, especially sialic acid-containing glycolipids, i.e. gangliosides are discussed. Gangliosides are known to be present mainly in the outer leaflet of cell membrane and also known to be one of the important constituents of membrane microdomains. The structural and functional changes in microdomain induced by gangliosides are involved in the physiological functions of gangliosides. Our studies for the involvement of gangliosides in anchorage-independent growth of tumor cells and in tumor cell invasion are described in the first half. In the latter half, we described our results that gangliosides can suppress the production of inflammatory cytokines in macrophages.
Although almost reports that describe the gangliosides' functions are in vitro studies and in vivo functions of gangliosides are hardly reported, gangliosides are contained in various foods and we daily ingest them. In fact, reports pointing out the nutritional significances of gangliosides are gradually increasing. The nutritional meaning and possibility of gangliosides are also discussed.

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