Generation of oxidant response to copper and iron nanoparticles and salts: Stimulation by ascorbate

The present work describes a two-stage approach to analyzing combustion-generated samples for their potential to produce oxidant stress. This approach is illustrated with the two commonly encountered transition metals, copper and iron. First, their abilities to generate hydroxyl radical were measured in a cell-free, phosphate-buffered saline solution containing ascorbate and/or citrate. Second, their abilities to induce heme oxygenase-1 in cultured human epidermal keratinocytes were assessed in cell culture. Combustion-generated copper oxide nanoparticles were active in both assays and were found to be soluble in culture medium. Depletion of glutathione in the cells or loading the cells with ascorbate greatly increased heme oxygenase-1 induction in the presence of copper. By contrast, iron oxide nanoparticles were active in the phosphate-buffered saline but not in cell culture, and they aggregated in culture medium. Soluble salts of copper and iron exhibited the same contrast in activities as the respective combustion-generated particles. The results suggest that the capability of combustion-generated environmental samples to produce oxidant stress can be screened effectively in a two step process, first in phosphate-buffered saline with ascorbate and subsequently in epithelial cell culture for those exhibiting activity initially. The results also point to an unanticipated interaction in cells of oxidant stress-generating metals with an antioxidant (ascorbate) that is usually missing in culture medium formulations. Thus, ascorbate supplementation of cultured human cells is likely to improve their ability to model the in vivo effects of particulate matter containing copper and other redox-active metals.     

Polyunsaturated fatty acid-cholesterol interactions: Domain formation in membranes

Polyunsaturated fatty acids (PUFA) constitute an influential group of molecules that promote health by an as yet unknown mechanism. They are structurally distinguished from less unsaturated fatty acids by the presence of a repeating CH-CH₂-CH unit that produces an extremely flexible chain rapidly reorienting through conformational states. The most highly unsaturated case in point is docosahexaenoic acid (DHA) with 6 double bonds. This review will summarize how the high disorder of DHA affects the properties of the membrane phospholipids into which the PUFA incorporates, focusing upon the profound impact on the interaction with cholesterol. Results obtained with model membranes using an array of biophysical techniques will be presented. They demonstrate DHA and the sterol possesses a mutual aversion that drives the lateral segregation of DHA-containing phospholipids into highly disordered domains away from cholesterol. These domains are compositionally and organizationally the opposite of lipid rafts, the ordered domain enriched in predominantly saturated sphingolipids “glued” together by cholesterol that is believed to serve as the platform for signaling proteins. We hypothesize that DHA-rich domains also form in the plasma membrane and are responsible, in part, for the diverse range of health benefits associated with DHA.     

微藻油脂组成的核磁共振碳谱表征

微藻油脂由于富含二十二碳六烯酸(DHA) 等多不饱和脂肪酸,且在培养过程中能吸收二氧化碳,因此在人类营养学和环境保护两个层面受到了前所未有的重视.为了深入考察微藻油脂的培养和提取过程,建立一种不破坏油脂就能区分油脂来源和特征的方法,是必不可少的.本文介绍了一种核磁共振碳谱表征方法.因为不必酯化,所以不仅可以测定双键数目和位置不同的脂肪酰基的摩尔比,而且测定了不同酰基在甘油烷基上的分布状况.本文分析了富含多不饱和脂肪酸的市售微藻油、富含饱和脂肪酸的棕榈油和富含单不饱和脂肪酸的橄榄油的组成,讨论了区分微藻微藻油中饱和脂肪酰基和不饱和脂肪酰基的测定方法和两种酰基的排列方式.     

长链多不饱和脂肪酸的替代来源——转基因油料作物

长链多不饱和脂肪酸(LCPUFA)对人体健康和发育具有极为重要的作用.由于海洋鱼类资源过度捕捞和环境污染的加剧,长链多不饱和脂肪酸的来源日益枯竭.利用转基因油料作物生产LCPUFA,特别是DHA和EPA成为目前研究的热点.归纳了LCPUFA合成代谢途径相关基因的最新研究进展,描述了利用植物基因工程合成长链多不饱和脂肪酸(特别是EPA和DHA)取得的主要成果,讨论了影响转基因油料作物合成DHA和EPA的关键因素,最后对利用转基因油料作物合成DHA和EPA的研究前景进行了展望.     

海洋真菌Thraustochytrium sp.FJN-10 Δ~4脱饱和酶基因的cDNA克隆及结构分析

海洋真菌Thraustochytriumsp.FJN-10是二十二碳六烯酸(Docosahexaenoic acid,DHA,C22:6n-3)的高产菌株。为阐明其DHA生物合成机制及采用基因工程技术提高DHA生物合成能力,通过RT-PCR扩增了DHA生物合成相关脱饱和酶基因的保守区,采用cDNA末端扩增技术(Rapid amplification of cDNA ends,RACE)获取全长基因,结果分析表明其克隆基因为Δ4脂肪酸脱饱和酶基因,开放阅读框由1560个核苷酸组成,共编码519个氨基酸,这是Thraus-tochytriumsp.FJN-10Δ4脂肪酸脱饱和酶基因研究的首次报道。     

Effect of feeding a docosahexaenoic acid-enriched nutriceutical on the quality of fresh and frozen-thawed semen in Holstein bulls

The aim of the current study was to investigate the effect of feeding a DHA-enriched nutriceutical on the in vitro quality and sperm motility parameters of fresh and frozen-thawed bull semen assessed by CASA. Samples were obtained from nineteen Holstein bulls used for semen collection at Semen Production Center, Karaj, Iran. Control group (n = 10) were fed a standard concentrate feed while treatment group bulls (n = 9) had this standard feed top dressed with 100 g of a commercially available DHA-enriched nutriceutical. Semen quality was assessed on ejaculates collected at the baseline and after 5, 9, and 12 weeks of supplementation. Classical semen evaluation, assessment of sperm motility (subjective and computer-assisted), viability (eosin-nigrosin), and hypo-osmotic swelling test (HOST) were conducted. Semen volume, sperm concentration, and consequently total sperm output were not affected by dietary treatment (P > 0.05). Feeding the nutriceutical was indeed found to affect sperm motility parameters assessed by CASA after 9 weeks of trial. The treatment has improved total motility (P < 0.01), progressive motility (P < 0.05), average path velocity (P < 0.05), HOST-positive (P < 0.01), and proportion of rapid spermatozoa (P < 0.01) in the fresh semen of bulls. Moreover, the proportion of viable spermatozoa increased (P < 0.05) in the ejaculates collected from nutriceutical-fed bulls compared to the control after 12 weeks of feeding trial. The post-thawed HOST and sperm motility data obtained by CASA did not differ between two groups (P > 0.05). On the other hand, dietary supplementation did not affect body weight, BCS and scrotal circumference. Consequently, it can be concluded that dietary DHA supplementation or its precursors, improve in vitro quality and motility parameters of fresh semen assessed by CASA in Holstein bulls. However, this effect was not pronounced in frozen-thawed semen.     

Resolvin E1 Receptor Activation Signals Phosphorylation and Phagocytosis

Resolvins are endogenous lipid mediators that actively regulate the resolution of acute inflammation. Resolvin E1 (RvE1; (5S,12R,18R)-trihydroxy-6Z,8E,10E,14Z,16E-eicosapentaenoic acid) is an endogenous anti-inflammatory and pro-resolving mediator derived from eicosapentaenoic acid that regulates leukocyte migration and enhances macrophage phagocytosis of apoptotic neutrophils to resolve inflammation. In the inflammatory milieu, RvE1 mediates counter-regulatory actions initiated via specific G protein-coupled receptors. Here, we have identified RvE1-specific signaling pathways initiated by the RvE1 receptor ChemR23. RvE1 stimulated phosphorylation of Akt that was both ligand- and receptor-dependent. RvE1 regulated Akt phosphorylation in a time (0–15 min)- and dose-dependent (0.01–100 nm) manner in human ChemR23-transfected Chinese hamster ovary cells. RvE1 stimulated phosphorylation of both Akt and a 30-kDa protein, a downstream target of Akt, identified using a phospho-Akt substrate antibody. The 30-kDa protein was identified as ribosomal protein S6, a translational regulator, and its phosphorylation was inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor (wortmannin) and an ERK inhibitor (PD98059) but not by a p38-MAPK inhibitor (SB203580). Ribosomal protein S6 is a downstream target of the PI3K/Akt signaling pathway as well as the Raf/ERK pathway. In ChemR23-expressing differentiated HL60 cells, RvE1 also stimulated the phosphorylation of ribosomal protein S6. In addition, RvE1 enhanced phagocytosis of zymosan A by human macrophages, which are inhibited by PD98059 and rapamycin (mTOR inhibitor). These results indicate that RvE1 initiates direct activation of ChemR23 and signals receptor-dependent phosphorylation. These phosphorylation-signaling pathways identified for RvE1 receptor-ligand interactions underscore the importance of endogenous pro-resolving agonists in resolving acute inflammation.