植物对氨基酸的吸收研究进展

氨基酸在提高植物产量、改善产品品质、增强植株抗逆性、保护生态环境等方面发挥着越来越重要的作用,在农业生产中越来越受到重视。本文简述了氨基酸含量、氨基酸种类和植物种类对植物吸收氨基酸的影响,并对氨基酸营养研究进行展望,以期提高人们对植物氨基酸营养的认识,促进氨基酸在农业中的应用和发展。     

大杯香菇辐射新株系各类氨基酸的遗传主成分分析

对大杯香菇辐射选育新株系的各类氨基酸总量进行了遗传主成分分析。结果表明,变异系数最大的为硫氨基酸总量,达到13．39％;其次为儿童氨基酸总量,变异系数为7．00％;其它变异系数较小分别为甜味氨基酸总量、芳香族氨基酸总量、必需氨基酸总量、支链氨基酸总量和鲜味氨基酸总量为5．69％、5．64％、5．19％、5．24％和5．06％;在相关性上,鲜味氨基酸总量与甜味氨基酸总量、支链氨基酸总量、芳香族氨基酸总量、儿童氨基酸总量和必需氨基酸总量是呈极显著和显著的正相关,甜味氨基酸总量与支链氨基酸总量、儿童氨基酸总量和芳香族氨基酸总量呈极显著和显著的正相关,硫氨基酸总量与儿童氨基酸总量呈极显著负相关,与必需氨基酸总量是呈极显著正相关;支链氨基酸总量与芳香族氨基酸总量、必需氨基酸总量是呈极显著,与儿童氨基酸总量呈显著正相关;芳香族氨基酸总量与儿童氨基酸总量和必需氨基酸总量是呈极显著和显著的正相关;主成分分析结果表明,前4个特征根在7个特征根中累计贡献率达97．14％,也就是前4个主成分对变异的贡献率达96．07％。在各类氨基酸总量指标选择上,首先对变异大的各类氨基酸总量进行选择是及其重要的。在辐射选育新株系选择时,应注意选择大杯香菇中硫氨基酸总量高的新株系。     

植物对氨基酸的吸收研究进展

氨基酸在提高植物产量、改善产品品质、增强植株抗逆性、保护生态环境等方面发挥着越来越重要的作用,在农业生产中越来越受到重视.本文简述了氨基酸含量、氨基酸种类和植物种类对植物吸收氨基酸的影响,并对氨基酸营养研究进行展望,以期提高人们对植物氨基酸营养的认识,促进氨基酸在农业中的应用和发展.     

大菱鲆鱼皮的氨基酸分析及评价

用常规方法测定了大菱鲆鱼皮的基本营养成分,用氨基酸自动分析仪分析其氨基酸构成,并对大菱鲆鱼皮中的氨基酸组成进行了营养学评价。结果表明,大菱鲆鱼皮蛋白质含量为14.8%,脂肪含量为1.8%,氨基酸含量为27.24%,其中含量较高的是甘氨酸、丙氨酸、脯氨酸和精氨酸,占总氨基酸的59.73%;必需氨基酸、甜味氨基酸、苦味氨基酸、鲜味氨基酸和涩味氨基酸的含量分别占总氨基酸的20.81%、60.61%、30.07%、10.43%和0.01%。甜味氨基酸、苦味氨基酸、鲜味氨基酸是大菱鲆鱼皮氨基酸的主要部分,构成了大菱鲆鱼皮的主要味道,大菱鲆鱼皮是一种口感柔滑、味道鲜美的理想补强食品。     

云南会泽引种玛卡中氨基酸组成与含量对营养与风味的影响

采用柱前衍生-液相色谱法(RP-HPLC)对云南会泽引种玛卡中水解氨基酸与游离氨基酸的种类与含量进行了测定。通过对玛卡中水解氨基酸的分析,发现玛卡中含有全部18种氨基酸,人体所必需的8种氨基酸占总氨基酸比例为36.75%,表明玛卡是具有较高营养价值的农作物,人体所必需的氨基酸中苯丙氨酸、络氨酸、蛋氨酸和半胱氨酸含量不足,影响了其整体营养价值;对影响感官的游离氨基酸进行分类,研究了各类味觉氨基酸对玛卡风味的影响。     

黑龙江林蛙不同部位中氨基酸的含量分析

采用茚三酮柱后衍生-氨基酸分析法,对黑龙江林蛙油、卵、皮中17种氨基酸的组成和含量进行测定。结果显示黑龙江林蛙油、卵、皮均含有17种氨基酸,氨基酸总量分别为356.5 mg.g-1,525.1 mg.g-1,752.5 mg.g-1,其中必需氨基酸分别占氨基酸总量的46.06%,38.89%,33.33%。通过对黑龙江林蛙油、卵、皮中氨基酸含量的对比分析,表明林蛙油中氨基酸的营养价值最高。     

基于打分矩阵的多类蛋白质折叠子的预测

依据蛋白质折叠子中氨基酸保守性,以氨基酸、氨基酸的极性、氨基酸的电性以及氨基酸的亲—疏水性为参数,从蛋白质的氨基酸序列出发,采用"一对多"的分类策略,通过构建打分矩阵和选取氨基酸序列模式片断,利用5种相似性打分函数对27类折叠子进行识别,最好的预测精度达到83.46%。结果表明,打分矩阵是预测多类蛋白质折叠子有效的方法。     

闽产李果实氨基酸组成及其营养分析

为了弄清不同闽产李（Prunus salicina）果实氨基酸含量、组成及营养价值,采用氨基酸自动分析仪 对不同李果实样品中各种氨基酸的含量进行检测,并对其组成进行比较分析。结果表明,李果实含有18种蛋白质氨基酸和3种非蛋白质氨基酸。田黄李的牛磺酸含量与蛋白质氨基酸含量均最高分别为26.54 mg/100 g和496.14 mg/100 g;皇后李的鸟氨酸、药用氨基酸、酸味氨基酸含量以及特殊功效蛋白质氨基酸的比重均最高分别为0.36 mg/100 g、364.67 mg/100 g、298.28 mg/100 g和73.45%;早熟胭脂李的γ-氨基丁酸含量最高为7.98 mg/100 g;大胭脂李的支链氨基酸含量最高为46.77 mg/100 g。李果实中氨基酸种类齐全、含量存在一定的差异,可根据不同的开发利用目标选择合适的品种。     

五种食用菌氨基酸含量的测定及营养评价

研究测定了五种食用菌中氨基酸的含量,并利用五种非生物学指标对蛋白质的营养价值进行评价。五种食用菌氨基酸种类齐全,必需氨基酸占氨基酸总量的百分比分别达到45.94%、37.62%、42.45%、41.54%、35.98%。茶树菇和姬松茸的限制性氨基酸为半胱氨酸和甲硫氨酸,鸡腿菇、香菇和黑木耳的限制性氨基酸是缬氨酸。不同的评价指标对蛋白质进行营养评价,评价结果会有所差异。     

不同产地天麻氨基酸的含量测定

氨基酸用途广泛,人们对氨基酸质量和品种的要求也越来越高.我国氨基酸从无到有,到现在的大市场份额,经历了五十多年的发展历程,其中包括谷氨酸、赖氨酸、苏氨酸和蛋氨酸在内的大品种氨基酸已经发展成为全球的主要供应品种,部分小品种氨基酸已形成自己的优势.绿色制造和现代生物技术的应用将成为氨基酸行业发展的主流.本文重点论述了我国氨基酸品种的现状、水平以及未来发展方向.     

Further studies on the properties of bile acids. I. Bile acid-induced changes of the action of drugs acting on the autonomic nervous system on the heart and blood vessels

The action of certain drugs on the autonomic system was studied under the influence of bile acids: 3,12-dihydroxycholanic acid (deoxycholic), 3,7,12-trihydroxycholanic acid (cholic), and 3,7,12-triketocholanic acid (dehydrocholic). The experiments were carried out on rat heart in vivo and on isolated rat vessel preparation. It was shown that bile acids reduced the stimulating effect of isoprenaline on rat heart and the relaxing effect on the blood vessels. An inversion of the effects of adrenaline and noradrenaline on the rat heart was observed, and an enhancement of the vasoconstrictor effect of these substances. Under the conditions of this experiment an inversion was noted of the action of acetylcholine on the heart and blood vessels.     

Nutritional properties of trans fatty acids

The role of trans fatty acids (TFA) present in partially hydrogenated fats widely consumed in food and their link with coronary heart disease has been examined in this review. Most of the studies carried out have been on the effects of TFA on blood-lipid profile. The perceived effects of TFA intake depend on the fat or oil with which they are compared and appears to be in between that of dietary saturated fats and monounsaturated fatty acids. When compared to saturated fat, TFA intake shows lower levels of total and LDL-cholesterol in blood. But when both TFA and saturated fatty acids are compared with cis fatty acids or native unhydrogenated oil, increase in total and LDL-cholesterol are noted. The effects of TFA on HDL-cholesterol and Lp(a) are not clearly established. The undesirable effects of TFA can be overcome by inclusion of essential fatty acids at a minimum of 2 energy per cent level in the diet. The link between trans fatty acid intake and coronary heart disease (CHD) are not unequivocally established.     

Genesis of fatty liver and hyperlipemia in the fetal guinea pig.

10 to 20% of [1-14C] palmitate injected into pregnant guinea pigs was recovered in lipids of their fetuses. From these data and the rate of transport of palmitate in maternal blood, it appears that placental transport of free fatty acids can account for the accumulation of lipids in late gestational fetuses. About 80% of the labeled palmitate in the fetus appeared initially in lipids of the liver. 14C appeared in plasma triglyceride fatty acids after a few minutes and subsequently accumulated in lipids of white and brown adipose tissue, suggesting that much of the palmitate deposited in adipose tissue were derived from hepatogenous triglyceride fatty acids. By contrast, 14C was usually maximal in heart and carcass lipids before it appeared in plasma triglyceride fatty acids. Lipoprotein lipase activity in fetal adipose tissue was low, and activity of cofactor protein of lipoprotein lipase in fetal blood plasma was much lower than that observed in other mammalian species. On the basis of these and earlier observations, it is concluded that the accumulation of triglycerides in liver and blood plasma of fetal guinea pigs during late gestation is at least partly the result of the large uptake of maternally derived free fatty acids by the fetal liver accompanied by rapid synthesis and secretion of triglyceride-rich very low density lipoproteins into the blood. However, limited uptake of triglyceride fatty acids in adipose tissue may contribute to the fatty liver and hyperlipemia.     

Fatty-acid composition of serum lipids predicts myocardial infarction.

During a follow-up of five to seven years 33 out of 1222 middle-aged men initially free of coronary heart disease sustained fatal or non-fatal myocardial infarction or died suddenly. The fatty-acid composition of serum triglycerides, phospholipids, and cholesterol esters had been measured at the start of the surveillance in these men and in a control group of 64 men matched for age, serum cholesterol and triglyceride concentrations, blood pressure, obesity, smoking, and one-hour glucose tolerance. Palmitic and stearic acids of phospholipids were significantly higher and linoleic and most polyunsaturated fatty acids, including arachidonic acid and eicosapentaenoic acid, of phospholipids were lower in the subjects who sustained coronary events compared with the controls. Linoleic acid tended to correlate negatively with blood pressure while other polyunsaturated fatty acids, especially eicosapentaenoic acid, exhibited a negative correlation with blood pressure and relative body weight in the controls but not in the subjects who sustained coronary events. These findings suggest that the fatty-acid pattern of serum phospholipids is an independent risk factor for coronary heart disease.     

The role of epicardial and perivascular adipose tissue in the pathophysiology of cardiovascular disease

Obesity, insulin resistance and the metabolic syndrome, are characterized by expansion and inflammation of adipose tissue, including the depots surrounding the heart and the blood vessels. Epicardial adipose tissue (EAT) is a visceral thoracic fat depot located along the large coronary arteries and on the surface of the ventricles and the apex of the heart, whereas perivascular adipose tissue (PVAT) surrounds the arteries. Both fat depots are not separated by a fascia from the underlying tissue. Therefore, factors secreted from epicardial and PVAT, like free fatty acids and adipokines, can directly affect the function of the heart and blood vessels. In this review, we describe the alterations found in EAT and PVAT in pathological states like obesity, type 2 diabetes, the metabolic syndrome and coronary artery disease. Furthermore, we discuss how changes in adipokine expression and secretion associated with these pathological states could contribute to the pathogenesis of cardiac contractile and vascular dysfunction.     

Alimentary proteins, amino acids and cholesterolemia

Numerous data from both epidemiological and experimental origins indicate that some alimentary proteins and amino acids in supplements can modify the blood LDL cholesterol, HDL cholesterol and total cholesterol. After an initial approval of the health claim for soy protein consumption for the prevention of coronary heart disease, more recently it has been concluded from an overall analysis of literature that isolated soy protein with isoflavones only slightly decrease LDL and total cholesterol. Other plant extracts and also some proteins from animal origin have been reported to exert a lowering effect on blood cholesterol when compared with a reference protein (often casein). The underlying mechanisms are still little understood. Individual amino acids and mixture of amino acids have also been tested (mostly in animal studies) for their effects on cholesterol parameters and on cholesterol metabolism. Methionine, lysine, cystine, leucine, aspartate and glutamate have been tested individually and in combination in different models of either normo or hypercholesterolemic animals and found to be able to modify blood cholesterol and/or LDL cholesterol and/or HDL cholesterol. It is however not known if these results are relevant to human nutrition.     

Characteristics of the early recovery period and the level of carbohydrate-lipid metabolic substrates after 24-hour immobilization hypothermia

The peculiarities of 24-hour hypothermia were studied in rats during immobilization and a 5-hour recovery period. The levels of glucose in blood and liver, glycogen in liver, skeletal muscles and heart, total lipids in liver and blood, nonesterified fatty acids in blood have shown that the speed of rewarming is limited both by the level of carbohydrate and lipid energy substrates.     

富含不饱和脂肪酸饲料对大鼠血液学指标及主要脏器的影响

目的探讨富含不饱和脂肪酸饲料对SD大鼠血液学指标及主要脏器的影响。方法以富含不饱和脂肪酸的青花椒籽油饲料饲喂断乳SD大鼠60d,试验结束时测定部分血清学和血液细胞学指标及脑、心脏、肝脏、肾脏、脾脏系数,并对心脏、肝脏、肾脏进行病理学观察。结果实验组雄性大鼠与正常对照组同性别大鼠相比,甘油三脂和低密度脂蛋白显著降低（P〈0．05）,实验组饲料极显著提高雄性大鼠大脑系数,极显著提高雄性和雌性大鼠肝脏和肾脏系数（P〈0．01）;心脏、肝脏、肾脏病理学观察结果为阴性。结论富含不饱和脂肪酸饲料对大鼠血清学指标有一定影响,对大鼠心、肝、。肾组织无明显影响。     

Membrane Effects of the n-3 Fish Oil Fatty Acids,which Prevent Fatal Ventricular Arrhythmias

Fish oil fatty acids are known to exert beneficial effects on the heart and vascular systems. We have studied the membrane effects on ion channel conductance by the n-3 fish oil fatty acids that account for these beneficial effects. We have confirmed that these fatty acids prevent fatal cardiac arrhythmias in a reliable dog model of sudden cardiac death. This finding was followed by experiments indicating that the n-3 fatty acids electrically stabilize heart cells and do so largely through modulation of the fast voltage-dependent Na⁺ currents and the L-type Ca²⁺ channels in a manner, which makes the heart cells resistant to arrhythmias. Others and we have demonstrated that these membrane effects on the heart can prevent fatal cardiac arrhythmias in humans.     

Effects of insulin on the metabolism of the isolated working rat heart perfused with undiluted rat blood

Working rat hearts were perfused with either buffer or with defibrinated, undiluted rat blood dialyzed to remove vasoconstrictor factors. With precautions taken for sterility in the preparation of the perfusate and the apparatus, hearts were obtained which were stable as judged by stroke rate and cardiac output. In these hearts, cardiac output and coronary flow averaged 46.0 and 1.7 ml/g heart per min, respectively. Perfusion with erythrocyte-free buffer depressed cardiac output by 30%, while coronary flow averaged 8.8 ml/g of heart per min. The mean stroke rate of blood-perfused hearts was 300 beats/min but only 240 beats/min during buffer perfusion. In blood-perfused hearts, insulin did not alter stroke rate but significantly lowered coronary flow. The hormone caused a transient increase in cardiac output in hearts perfused with buffer. Insulin did not alter glucose uptake in buffer-perfused hearts but increased lactate release in perfusions with blood. Both serum fatty acids and triacylglycerol fatty acids were significant metabolic fuels in hearts perfused with undiluted blood. The preparation described would appear to be potentially useful for the study of myocardial metabolism in vitro.