We have reported that orally administrated acetate contributed to suppression of lipogenesis in the liver and to reduction of lipid accumulation in the adipose tissue of Otsuka Long-Evans Tokushima Fatty (OLETF) rats. The aim of this study was to investigate the effect of acetate on skeletal muscle and adipose tissues. Treatment with acetate showed a higher rate of oxygen consumption and a smaller size of lipid droplets in white adipose and brown adipose tissues. An analysis by Northern blotting revealed that the transcripts of myoglobin and Glut4 genes in the abdominal muscle of the OLETF rats were increased by acetate treatment, while the transcripts of lipolytic genes increased in the white adipose and brown adipose tissues. It is possible that acetate has effects on lipid metabolism in the skeletal muscles and the adipose tissues, and has functions that work against obesity and obesity-linked type 2 diabetes.

Flower stalks of Pulsatilla cernua, an early spring herb in north temperate Asia, changed position from erect to pendulous and back to erect during 6-10 d anthesis. We tested three possible explanations for this movement. Our results showed that (1) this movement is unlikely to be a mechanism to attract pollinators or enhance pollen output, because no pollinator preference was observed between erect and pendulous flowers and we found no buzz-pollination in this species; (2) hand self-pollination yielded higher seed set than open pollination in the field, but spontaneous selfing rarely occurred. Among open-pollinated flowers, seed set was depressed by emasculation, indicating that in the presence of insects, self-pollen provided reproductive assurance in this protogynous and self-compatible species. However, the change in flower orientation cannot be explained as reproductive assurance in that even self-pollination largely depended on pollinator visits rather than gravity. (3) A pollen germination experiment indicated that pollen damage by water is serious in this species. We deduced that the bending of the flower stalk during anthesis was to avoid rain damage to pollen grains in this species. During the 3-6 d period of pollen presentation, the petals elongated and were covered with unwettable hairs. Together with flower stalk movement, this was enough to protect the organs inside the flower from rain. This movement of the flower stalk seems to be important to maintain pollen viability in a rainy habitat with a scarcity of pollinators.

12/15-lipoxygenase (12/15-LO) enzyme and products have been associated with inflammation and atherosclerosis. However, the mechanism of effects of the 12/15-LO products has not been fully clarified. To study the role of 12/15-LO in cytokine expression, experiments with direct additions of the12/15-LO products, 12(S)-hydroxyeicosa tetraenoic acid or 12(S)-hydroperoxyeicosa-5Z, 8Z, 10E, or 14Z-tetraenoic acid to macrophages were first carried out, and results showed that the 12/15-LO products stimulated mRNA and protein expression of IL-6 and TNF-alpha in a dose-dependent manner. In contrast, an inactive analogue of 12(S)-hydroxyeicosa tetraenoic acid had no effect. To further explore the role of endogenous 12/15-LO in cytokine expression, we used an in vitro and in vivo model to test the effect of 12/15-LO overexpression. The models included Plox-86 cells, a J774A.1 cell line that stably overexpresses leukocyte-type 12/15-LO and primary mouse peritoneal macrophages (MPMs) from 12/15-LO transgenic mice. The results showed a clear increase in IL-6 and TNF-alpha expression in Plox-86 cells and MPMs from 12/15-LO transgenic mice, compared with mock-transfected J774A.1 cells and MPMs from control C57BL6 mice. IL-1beta, IL-12, and monocyte chemoattractant protein (MCP)-1 mRNA were also increased in Plox-86 cells. These data clearly suggest a clear role of 12/15-LO pathway in cytokine production. We also demonstrated that signaling pathways including protein kinase C, p38 MAPK (p38), c-jun NH(2)-terminal kinase as well as nicotinamide adenine dinucleotide phosphate oxidase are important for 12-(S)-hydroxyeicosatetraenoic acid-induced increases in IL-6 and TNF-alpha gene expression. These results suggest a potentially important mechanism linking 12/15-LO activation to chronic inflammation and atherosclerosis.

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When arachidonate 12-lipoxygenase purified from porcine leukocytes was incubated aerobically with 1-palmitoyl-2-arachidonoyl-~n-glycero-3-phosphocholine, the phospholipid reacted at up to 30% of the rate of a free fatty acid substrate; the esterified arachidonic acid was oxygenated predominantly to the (1 25')-12-hydroperoxy product. The porcine leukocyte enzyme was also capable of metabolizing phosphatidylcholine containing esterified (15s)-15-hydroperoxy-5,8,11,13-eicosatetraenoic acid ; oxygenation occurred predominantly at the 14R position. Reaction with mitochondrial and endoplasmic membranes of rat liver produced esterified (12S)-12-hydroperoxy-5,8,1O,lbeicosatetraenoic acid and (13S)-13-hydroperoxy-9,ll-octadecadienoic acid as major oxygenation products. Thus, porcine leukocyte 12-lipoxygenase is capable of oxygenating not only free polyenoic fatty acids but also more complex substrates such as phospholipids and biomembranes. In contrast, the human platelet 12-lipoxygenase is almost inactive with these esterified polyenoic fatty acids. In regard to the function of these enzymes, the leukocyte-type of 12-lipoxygenase has similar catalytic activities to the mammalian 15-lipoxygenase and its physiological function may include the structural modification of membrane lipids.The classical concept of the arachidonic acid cascade comprises the liberation of free polyenoic fatty acids, particularly arachidonic acid, from membrane phospholipids and its subsequent oxygenation via the cyclooxygenase or lipoxygenase pathways forming biologically active compounds such as prostaglandins, thromboxane and leukotrienes [ 11. There is an alternative concept of direct oxygenation of esterified arachidonic acid within biomembranes. The direct oxygenation of membrane lipids has proven to be minimal for the cyclooxygenase [2, 31 and 5-lipoxygenase [4, 51. The reports on the in vitro interaction of the rabbit reticulocyte and soybean lipoxygenases with phospholipids [5 -91 and of the reticulocyte enzyme with biomembranes [ 101 indicated the capability of 15-lipoxygenases of directly oxygenating ester lipids. In intact reticulocytes, the phospholipids of the mitochondrial membranes were found to be the preferred substrate for the lipoxygenase [ll]. These data, as well as the biological dynamics of this enzyme [12], led to the hypothesis that the reticulocyte 15-lipoxygenase was implicated in the breakdown of the mitochondria during red cell maturation [13].Two types of 12-lipoxygenase are distinguishable in terms of substrate specificity [14]. Porcine leukocytes contain a 124poxygenase which has a broad substrate specific- ity. The enzyme, designated as the leukocyte-type, is active not only with arachidonic acid and other C,, acids, but also with C,, acids such as linoleic and linolenic acids [14-161. This catalytic activity of the leukocyte-type enzyme is similar to that of the reticulocyte 15-lipoxygenase. Human platelets contain a 12-lipoxygenase (designated as the platelettype) which is almost inactive with C,, acids. Compar...