Morphological changes in the central vacuole ofBlastocystis hominis during in vitro culture

Summary Morphological changes in the central vacuole during the growth in in vitro culture ofBlastocystis hominis were investigated by light and electron microscopy. Most cells in log phase and an early stationary phase showed a positive staining reaction in the central vacuole with PAS or Sudan black B stain, whereas cells in late stationary phase showed few positive reactions. Electron microscopic observations revealed that 95% ofB. hominis cells in log phase and 50% of cells in early stationary phase, had a substantial accumulation of electron-dense material in the central vacuole. In contrast, only 25% of the organisms in late stationary phase had an electron-dense central vacuole, while more than 50% of cells had an electron-lucent central vacuole. These results indicate thatB. hominis accumulated carbohydrates and lipids in the central vacuole during cell growth and that the organism probably consumed these metabolic substances during stationary growth. Therefore, it is strongly suggested that the central vacuole is an important organelle for storage of metabolic substances, such as carbohydrates and lipids, required for cell growth.Abbreviations PBS phosphate-buffered saline - PAS periodic acid-Schiff     

Free fatty acid profiles in preeclampsia

Preeclampsia has many characteristics similar to the metabolic syndrome. One of these is aberrant lipid metabolism. We studied free fatty acid (FFA) profiles at baseline and after oral glucose load in 21 preeclamptic and 11 normotensive pregnant women. Insulin sensitivity was measured by intravenous glucose tolerance test.We found that serum total FFA concentrations at baseline were 67% higher in preeclamptic than in normotensive pregnancies (P=0.0002). The difference between the two groups was largest in the concentrations of oleic (75%), linoleic (129%) and arachidonic (315%) acids. Oral intake of glucose suppressed total FFA in preeclamptic women by 40% (95% CI 32.1–46.1%, P<0.0001) but only 24% in control women (95% CI 0.01–42.0%, P=0.045). Insulin sensitivity, which in preeclamptic women was 37% lower (P=0.009), was unrelated to total or any individual FFA concentration.We concluded that preeclamptic women have higher circulating FFA concentrations, which despite insulin resistance are suppressed by oral glucose loading.     

Biomolecular investigation of human substantia nigra in Parkinson's disease by synchrotron radiation Fourier transform infrared microspectroscopy

Synchrotron radiation based-Fourier transform infrared microspectroscopy was used for preliminary investigation of the chemical composition and morphologies of the human substantia nigra of brain between normal and Parkinson's diseased tissues. The studies were carried out for thin tissue sections, focusing more particularly on nerve cell bodies, that are affected in Parkinson's disease (PD). The major spectral differences between normal (control) and PD tissues were identified at the following vibrational frequencies: 2930, 2850, 1655, 1380, 1236, 1173 and 1086 cm(-1). The infrared imaging of these biochemical markers show that for control cases the protein and nucleic acids functional groups (bands at: approximately 3300, approximately 3100, approximately 1655, approximately 1545, approximately 1240, approximately 1080 cm(-1)) are located mainly in the cell body. The spatial distribution of the band at 1740 cm(-1) (ester carbonyl stretching band) is quite dissimilar to the others, while it exhibits a minimal concentration in the cell body area. Contrarily, in PD samples, no clear evidence of variation of any of the vibrational fingerprint between cell body and the surrounding was noticed. Moreover, decrease of protein to lipid ratio as well as increase of amide I/amide II ratio were observed for PD case. The preliminary results strengthen the hypothesis that PD is a multietiological disorder. Moreover, the reported results clearly indicate that, in addition to a distinct visual observation, the diseased nerve cells exhibits change of their biochemical composition. It suggests that disturbances of normal functioning of SN neurons appear before their morphological atrophy.     

Selective mortality of a coral reef damselfish: role of predator–competitor synergisms

Phenotypic variability within cohorts of juvenile organisms can serve as the basis for selective mortality. Previous studies have demonstrated the important role that predators play in this process but not the impact of competitors on selective predation. We use a combination of lab and field studies to evaluate the effect of the presence of adult competitor damselfish (Dascyllus aruanus and Pomacentrus moluccensis; family Pomacentridae) on the selective mortality of newly-arrived (settled) lemon damselfish (P. moluccensis) by resident predator fishes (Pseudochromis fuscus Pseudochromidae and Cheilodipterus quinquelineatus Apogonidae). Lab trials consisted of mesocosm experiments in which the behaviour, mortality, and physiological condition (measured as lipid content) of surviving P. moluccensis settlers from each of three treatments: (1) predators absent, (2) predators present, and (3) predators and competitors present, were compared. The field study involved stocking newly settled P. moluccensis on natural bommies (patch reefs) which had either been subject to a partial removal of resident fish (predators and competitors) or left alone. Results indicated there was very strong condition-based selective mortality in both the lab and field trials. In both cases there was a strong positive relationship between mortality and the lipid content of surviving fish; implying low-condition fish were selectively removed. The mesocosm trials indicated that the strength of mortality as well as condition selectivity was higher when competitors were present than when they were absent. Behavioural observations in the mesocosm study suggest that attention by juvenile P. moluccensis to the movements and occasional chases of the competitors (especially D. aruanus) reduced their vigilance to the predators. These results suggest the important and interactive roles which condition of newly settled reef fish and interspecific competition can play in the outcomes of post-settlement predation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Lipids of the hexane extract from the roots of medicinal boraginaceous species

The chemical compositions of hexane extracts of the lipid fraction of the roots of the medicinal Boraginaceous species Alkanna tinctoria, Onosma heterophylla, Macrotomia densiflora and Onosma hispidium are presented and their phytochemical relevance evaluated. The predominating fatty acids in all of the root lipids were stearic, palmitic, oleic, linoleic and gamma-linolenic acids, while the latter and stearidonic acid predominated in the seeds and leaves of various Boraginaceous species. The indigenous presence of methyl, ethyl and isopropyl esters of fatty acids, reported for the first time in the roots of higher plants, is considered to be of particular importance in the biosynthesis of fatty substances. The results suggest the use of fatty acids as chemotaxonomic markers for Boraginaceous species and the utilisation of Boraginaceous species as new commercial sources for fatty acids with valuable medicinal and nutritional properties.     

Ontogeny of the Major Xenobiotic‐Metabolizing Enzymes Expression and the Dietary Lipids Modulatory Effect in the Rat Dimethylbenz(a)anthracene‐Induced Breast Cancer Model

Breast cancer is the most common malignancy in women worldwide. Environmental factors such as xenobiotic exposure and lifestyle and nutrition play a key role in its etiology. This study was designed to evaluate the age‐related changes in the expression of major xenobiotic‐metabolizing enzymes (XMEs) in the rat liver and the mammary gland in the dimethylbenz(a)anthracene‐induced breast cancer model. The influence of dietary lipids on the ontogeny of XMEs was also evaluated. mRNA and protein levels of phase I (CYP1A1, CYP1A2, and CYP1B1) and phase II (NAD(P)H:quinone acceptor oxidoreductase 1 and GSTP1) enzymes were analyzed, as well as their regulation by AhR and Nrf2, respectively. Results showed differences in the phase I enzymes expression, whereas little changes were obtained in phase II. High corn oil and olive oil diets differentially influenced the expression of age‐related changes, suggesting that the different susceptibility to xenobiotic exposure depending upon the age may be modulated by dietary factors.     

利用平板反应器大量培养高产油绿藻——尖状栅藻的生长和油脂积累规律

以新近分离的淡水绿藻--尖状栅藻(Scenedesmus acuminatus)为研究对象,将改良的BG-11培养基中的初始NaNO₃浓度降低为6.0mmol/L和3.6mmol/L,利用新设计的内置拉筋平板式光生物反应器对尖状栅藻(S. acuminatus)进行大量培养。测定不同时相的生物量、总脂含量、脂组分含量及脂肪酸组成和含量,分析尖状栅藻(S. acuminatus)大量培养时的生长和油脂积累规律。当初始NaNO₃浓度为6mmol/L时其最高生物量(6.27g/L)明显高于初始NaNO₃浓度为3.6mmol/L时的生物量(5.30g/L);而最高的总脂含量在初始NaNO₃浓度为3.6mmol/L时获得为干重的56.6%,高于初始NaNO₃浓度为6mmol/L时的总脂含量(51.6%)。总脂经硅胶柱层析分级后得到三种类型的脂组分:中性脂、糖脂和磷脂,随着培养时间的延长中性脂含量逐渐增加,培养至18d后,中性脂的含量分别达到总脂的 90.9%(6 mmol/L NaNO₃)和 92.0%(3.6 mmol/L NaNO₃)及干重的 47.5%(6.0 mmol/L NaNO₃)和 51.4%(3.6 mmol/L NaNO₃)。主要脂肪酸组成为棕榈酸、棕榈油酸、硬脂酸、油酸、亚麻油酸和亚麻酸,这六种脂肪酸在不同时相的含量变化范围分别为89.92%~96.18%(占总脂肪酸)和12.5%~50.7%(占细胞干重)。总脂、中性脂及总脂肪酸单位体积产率分别为:0.18 g/L/d,0.16 g/L/d和0.15 g/L/d(6.0 mmol/L NaNO₃)及0.16 g/L/d,0.15 g/L/d和0.15 g/L/d(3.6 mmol/L NaNO₃)。研究结果表明,尖状栅藻(S. acuminatus)是一株易于规模化培养、脂肪酸组成适合于生物柴油生产的高产油微藻。     

A Toxin-based Probe Reveals Cytoplasmic Exposure of Golgi Sphingomyelin

Although sphingomyelin is an important cellular lipid, its subcellular distribution is not precisely known. Here we use a sea anemone cytolysin, equinatoxin II (EqtII), which specifically binds sphingomyelin, as a new marker to detect cellular sphingomyelin. A purified fusion protein composed of EqtII and green fluorescent protein (EqtII-GFP) binds to the SM rich apical membrane of Madin-Darby canine kidney (MDCK) II cells when added exogenously, but not to the SM-free basolateral membrane. When expressed intracellularly within MDCK II cells, EqtII-GFP colocalizes with markers for Golgi apparatus and not with those for nucleus, mitochondria, endoplasmic reticulum or plasma membrane. Colocalization with the Golgi apparatus was confirmed by also using NIH 3T3 fibroblasts. Moreover, EqtII-GFP was enriched in cis-Golgi compartments isolated by gradient ultracentrifugation. The data reveal that EqtII-GFP is a sensitive probe for membrane sphingomyelin, which provides new information on cytosolic exposure, essential to understand its diverse physiological roles.     

FTY720 (Gilenya) phosphate selectivity of sphingosine 1-phosphate receptor subtype 1 (S1P1) G protein-coupled receptor requires motifs in intracellular loop 1 and transmembrane domain 2

FTY720 phosphate (FTY720P) is a high potency agonist for all the endothelial differentiation gene family sphingosine 1-phosphate (S1P) receptors except S1P receptor subtype 2 (S1P(2)). To map the distinguishing features of S1P(2) ligand recognition, we applied a computational modeling-guided mutagenesis strategy that was based on the high degree of sequence homology between S1P(1) and S1P(2). S1P(2) point mutants of the ligand-binding pocket were characterized. The head group-interacting residues Arg3.28, Glu3.29, and Lys7.34 were essential for activation. Mutation of residues Ala3.32, Leu3.36, Val5.41, Phe6.44, Trp6.48, Ser7.42, and Ser7.46, predicted to interact with the S1P hydrophobic tail, impaired activation by S1P. Replacing individual or multiple residues in the ligand-binding pocket of S1P(2) with S1P(1) sequence did not impart activation by FTY720P. Chimeric S1P(1)/S1P(2) receptors were generated and characterized for activation by S1P or FTY720P. The S1P(2) chimera with S1P(1) sequence from the N terminus to transmembrane domain 2 (TM2) was activated by FTY720P, and the S1P(2)(IC1-TM2)(S1P1) domain insertion chimera showed S1P(1)-like activation. Twelve residues in this domain, distributed in four motifs a-d, differ between S1P(1) and S1P(2). Insertion of (78)RPMYY in motif b alone or simultaneous swapping of five other residues in motifs c and d from S1P(1) into S1P(2) introduced FTY720P responsiveness. Molecular dynamics calculations indicate that FTY720P binding selectivity is a function of the entropic contribution to the binding free energy rather than enthalpic contributions and that preferred agonists retain substantial flexibility when bound. After exposure to FTY720P, the S1P(2)(IC1-TM2)(S1P1) receptor recycled to the plasma membrane, indicating that additional structural elements are required for the selective degradative trafficking of S1P(1).     

Fatty acids,starch and biomass of Scots pine needles and roots in open-air ozone exposure

Scots pine (Pinus sylvestris L.) seedlings were fumigated with 1.2–1.5 x ambient ozone (cumulative exposure) over 2 seasons in an open-air experiment. Starch and fatty acid concentrations were analyzed in needle and root tissue in the summer, autumn and early winter. Seedling growth was determined by measuring the height of the stem and the total shoot and root biomass. Significant decreases in growth were found in exposed seedlings, even though visible symptoms were lacking. Almost significant reductions in needle and root starch concentrations were found. In the ozone treated foliage, significant increases in myristic acid (140) were detected, but the major fatty acids remained unchanged. Fatty acid ratios showed that the degree of unsaturation decreased in treated needles in the summer. In the roots of ozone treated seedlings, changes in fatty acids were different from those in the foliage. Decreases of the main root fatty acids (160, 180, 181, 18:2, 183) were detected in the summer. These results show that Scots pine is susceptible to enhanced levels of ozone. If the tropospheric ozone levels continue to increase it may have deleterious effects on Scots pine forests in Finland.