Characterization and biosynthesis of lipids in Paulinella micropora MYN1. Evidence for efficient integration of chromatophores into cellular lipid metabolism.
Paulinella 微孢菌 myn1 脂质的表征和生物合成。色素团有效整合到细胞脂质代谢中的证据。
- 作者列表："Sato N","Yoshitomi T","Mori-Moriyama N
:The chromatophores in the cells of photosynthetic Paulinella species, once believed to be endosymbiotic cyanobacteria, are photosynthetic organelles, that are distinct from chloroplasts. The chromatophore genome is similar to the genomes of α-cyanobacteria and encodes about 1000 genes. Therefore, the chromatophore is an intriguing model of organelle formation. Here, we analyzed the lipids of Paulinella micropora MYN1 to verify that this organism is a composite of cyanobacterial descendants and a heterotrophic protist. We detected glycolipids and phospholipids, as well as a betaine lipid diacylglyceryl-3-O-carboxyhydroxymethylcholine (DGCC), previously detected in many marine algae. Cholesterol was the only sterol component detected, suggesting that the host cell is similar to animal cells. The glycolipids, presumably present in the chromatophores, contained mainly C16 fatty acids, whereas other classes of lipids, presumably present in the other compartments, were abundant in C20 and C22 polyunsaturated fatty acids. This suggests that chromatophores are metabolically distinct from the rest of the cell. Metabolic studies using isotopically labeled substrates showed that different fatty acids are synthesized in the chromatophore and the cytosol, which is consistent with the presence of both Type I and Type II fatty acid synthases, supposedly present in the cytosol and the chromatophore, respectively. Nevertheless, rapid labeling of the fatty acids in triacylglycerol and phosphatidylcholine by photosynthetically fixed carbon suggested that the chromatophores efficiently provide metabolites to the host. The metabolic as well as ultrastructural evidence suggests that chromatophores are tightly integrated into the whole cellular metabolism.
: 曾经被认为是内共生蓝藻的光合泡藻细胞中的色素团是光合细胞器，不同于叶绿体。色素细胞基因组与 α-蓝藻的基因组相似，编码约 1000 个基因。因此，色素细胞是细胞器形成的一个有趣的模型。在这里，我们分析了 Paulinella micropora MYN1 的脂质，以验证该微生物是蓝藻后代和异养虫的复合物。我们在许多海洋藻类中检测到糖脂和磷脂，以及甜菜碱脂质 diacylglyceryl-3-O-carboxyhydroxymethylcholine (DGCC)。胆固醇是唯一检测到的固醇成分，提示宿主细胞与动物细胞相似。糖脂，推测存在于色素组中，主要含有 C16 脂肪酸，而其他类脂质，推测存在于其他隔室中，在 C20 和 C22 多不饱和脂肪酸中含量丰富。这表明色素团在代谢上不同于细胞的其余部分。使用同位素标记底物的代谢研究表明，在色素载体和胞质溶胶中合成了不同的脂肪酸，这与 I 型和 II 型脂肪酸合成酶的存在一致, 推测分别存在于胞质溶胶和色素载体中。尽管如此，光合固定碳对三酰甘油和磷脂酰胆碱中脂肪酸的快速标记表明，色素团有效地向宿主提供代谢物。代谢和超微结构证据表明，色素团紧密整合到整个细胞代谢中。
METHODS:BACKGROUND:Given the importance of habitual dietary protein intake, distribution patterns and dietary sources in the aetiology of age-related declines of muscle mass and function, the present study examined these factors as a function of sex and age in Irish adults aged 18-90 years comprising The National Adult Nutrition Survey (NANS). METHODS:In total, 1051 (males, n = 523; females, n = 528) undertook a 4-day semi-weighed food diary. Total, body mass relative intake and percentage contribution to total energy intake of dietary protein were determined in addition to protein distribution scores (PDS), as well as the contribution of food groups, animal- and plant-based foods to total protein intake. RESULTS:Total and relative protein intake [mean (SD)] were highest in those aged 18-35 years [96 (3) g day , 1.32 (0.40) g kg day ], with lower protein intakes with increasing age (i.e. in adults aged ≥65 years [82 (22) g, 1.15 (0.34) g kg day , P < 0.001 for both]. Differences in protein intake between age groups were more pronounced in males compared to females. Protein distribution followed a skewed pattern for all age groups [breakfast, 15 (10) g; lunch, 30 (15) g; dinner, 44 (17) g]. Animal-based foods were the dominant protein source within the diet [63% (11%) versus 37% (11%) plant protein, P < 0.001]. CONCLUSIONS:Protein intake and the number of meals reaching the purported threshold for maximising post-prandial anabolism were highest in young adults, and lower with increasing age. For main meals, breakfast provided the lowest quantity of protein across all age categories and may represent an opportunity for improving protein distribution, whereas, in older adults, increasing the number of meals reaching the anabolic threshold regardless of distribution pattern may be more appropriate.
METHODS:BACKGROUND:Low cardiorespiratory fitness (CRF) increases risk of all-cause mortality and cardiovascular events. Periodic CRF assessment can have an important preventive function. OBJECTIVE:To develop a protocol-free method to estimate CRF in daily life based on heart rate (HR) and body acceleration measurements. METHODS:Acceleration and HR data were collected from 37 subjects (M=49%) while performing a standardized laboratory activity protocol (sitting, walking, running, cycling) and during a 5-days free-living monitoring period. CRF was determined by oxygen uptake (VO2max) during maximal exercise testing. A doubly-labeled water validated equation was used to predict total energy expenditure (TEE) from acceleration data. A fitness index was defined as the ratio between TEE and HR (TEE-pulse). Activity recognition techniques were used to process acceleration features and classify sedentary, ambulatory and other activity types. Regression equations based on TEE-pulse data from each activity type were developed to predict VO2max. RESULTS:TEE-pulse measured within each activity type of the laboratory protocol was highly correlated to VO2max (r from 0.74 to 0.91). Averaging the outcome of each activity-type specific equation based on TEE-pulse from the laboratory data led to accurate estimates of VO2max (RMSE: 300.0 mlO2/min or 10%). The difference between laboratory and free-living determined TEE-pulse was 3.7 ± 11% (r =0.85). The prediction method preserved the prediction accuracy when applied to free-living data (RMSE: 367 mlO2/min or 12%). CONCLUSIONS:Measurements of body acceleration and HR can be used to predict VO2max in daily life. Activity-specific prediction equations are needed to achieve highly accurate estimates of CRF.
METHODS:OBJECTIVE:Postprandial dyslipidemia is a common feature of insulin resistant states and contributes to increased cardiovascular disease risk. Recently, bile acids have been recognized beyond their emulsification properties as important signaling molecules that promote energy expenditure, improve insulin sensitivity, and lower fasting lipemia. While bile acid receptors have become novel pharmaceutical targets, their effects on postprandial lipid metabolism remain unclear. Here we investigated the potential role of bile acids in regulation of postprandial chylomicron production and triglyceride excursion. Approach and Results: Healthy C57BL/6 mice were given an intraduodenal infusion of taurocholic acid (TA) under fat-loaded conditions and circulating lipids were measured. Targeting of bile acid receptors was achieved with GW4064, a synthetic agonist to the farnesoid X receptor (FXR), and with deoxycholic acid (DCA), an activator of the Takeda G-protein-coupled receptor 5. TA, GW4064, and DCA treatments all lowered postprandial lipemia. FXR agonism also reduced intestinal triglyceride content and activity of microsomal triglyceride transfer protein, involved in chylomicron assembly. Importantly, TA effects (but not DCA) were largely lost in FXR knockout mice. These bile acid effects are reminiscent of the anti-diabetic hormone glucagon-like peptide-1 (GLP-1). While the GLP-1 receptor agonist exendin-4 retained its ability to acutely lower postprandial lipemia during bile acid sequestration and FXR deficiency, it did raise hepatic expression of the rate limiting enzyme for bile acid synthesis. CONCLUSIONS:Bile acid signaling may be an important mechanism of controlling dietary lipid absorption and bile acid receptors may constitute novel targets for the treatment of postprandial dyslipidemia.