Fat Metabolism in Germinating Citrullus vulgaris

A column chromatographic technique, enabling identificationand quantitative estimation of fatty acids, has been employedto study fat metabolism in Citrullus during germination in thelight. This plant is characterized by an unusually rapid disappearanceof storage fat as the cotyledons expand and turn green. In spiteof the high catabolic activity there is no evidence for accumulationof free fatty acids or short-chain fatty acids at this stage.Information on this point derived from acid value or saponificationvalue of the oil is shown to be untrustworthy. Citrullus seed fat contains the following percentages of acids:linoleic 70·6, oleic 7·2, palmitic 10·1,stearic 11·2, and arachidic 0·6, and careful analysishas also revealed small amounts of octadecatrienoic acids, bothconjugated and non-conjugated. All the major acids are brokendown at rates proportionate to the quantities originally present,with the exception of oleic acid which is metabolized somewhatmore rapidly. ‘Linolenic’ acid is synthesized in the expandinggreen cotyledons and the fatty acid composition of the latter,in the late germination stages, resembles that of a green leafand is very different from that of the seed. The results suggest a rapid removal of storage fat from thecotyledons and concomitant formation in small quantity of atypial leaf fat as the new photo-synthetic function develops.     

PPAR基因与脂肪代谢调控

过氧化物酶体增值剂激活受体(PPARs)基因属于类固醇/甲状腺/维甲酸受体超家族,有3个亚型,即：PPAR-α、PPAR-β和PPAR-γ。PPARs具有多种生物学功能,如增强机体对胰岛素敏感性,调节体内糖平衡等,尤其在脂肪分化、生成等多方面起到重要作用,是目前的研究热点,文章从PPARs基因的结构,表达及功能等方面讨论了其与脂肪代谢调控的关系。     

CO2浓度升高对大豆糖代谢和脂肪代谢影响的研究

为明确大气CO2浓度升高对大豆糖代谢和脂肪代谢的影响,本研究以高油大豆品种"晋大70"为材料,利用控制气室设置CK(CO2浓度为400μmol/mol)和EC(CO2浓度为600μmol/mol)两个处理,大豆整个生育期均在控制气室内,在大豆鼓粒期利用便携式气体交换系统LI-6400测定光合参数,测定叶绿素含量、糖代谢...     

Fat Metabolism in Germinating Citrullus vulgaris. Part II

Breakdown of fat in watermelon seedlings germinated in the darkoccurs in essentially the same way as in the light. Free fattyacids do not accumulate and the composition of the lipid remainsalmost unchanged during its rapid utilization. The low weight of ‘protoplasmic lipid’ remainingin the etiolated cotyledons after the storage fat has disappearedcontains a lower proportion of linolenic acid than that fromgreen cotyledons of a corresponding age. The weight of phosphatide (lipid P) per cotyledon increases both in light- anddark-grown seedlings until 8 days, thereafter declining in thedark but continuing to rise in the light. Phosphatide and glyceridefractions from the same fat resemble each other fairly closelyin fatty acid composition.     

The Effect of Low‐Intensity Exercise Training on Fat Metabolism of Obese Women

Objective: Previous studies have shown that fat metabolism is different in upper body (UB) and lower body (LB) obese women. The present study investigated whether the effect of low‐intensity exercise training on fat metabolism is different in UB and LB obese premenopausal women. Research Methods and Procedures: Twenty‐one healthy, premenopausal women with either LB obesity (waist‐to‐hip ratio of ≤0.79; n = 8) or UB obesity (waist‐to‐hip ratio of ≥0.85; n = 13) participated in the present study. The UB obese women were matched and randomly divided in an exercise training group (UB) and a nonexercising control group (UB‐C). Subjects in the UB and LB groups participated in a low‐intensity exercise training program (40% Vo ₂max) three times per week for 12 weeks. Before and after the intervention, measurements of fat metabolism at rest and during exercise, body composition, and maximal aerobic capacity were performed. Results: Exercise training did not change the respiratory exchange ratio at rest in the UB and LB groups. During exercise, relative fat oxidation increased in the UB group by 19% (p < 0.05), whereas no change in the LB and UB‐C groups was found. Plasma free fatty acid oxidation did not change by exercise training, and nonplasma fatty acid oxidation tended to increase in the UB group compared with the UB‐C group (p = 0.08). Discussion: Low‐intensity exercise training increased the contribution of fat oxidation to total energy expenditure during exercise but not at rest in UB obese women. Exercise training had no significant effect on fat metabolism in the LB obese women.