猪体内囊尾蚴发育过程中能量代谢酶组织化学观察

采用酶组织化学技术半定量观察猪体内囊尾蚴发育过程中乳酸脱氢酶 (L DH)、琥珀酸脱氢酶 (SDH)、谷氨酸脱氢酶 (GDH)、三磷酸腺苷酶 (ATPase)、酸性磷酸酶 (ACP)、碱性磷酸酶 (AKP)、6 -磷酸葡萄糖酶 (G6 Pase)、黄嘌呤氧化酶 (XOD)、脂酶 (FE)活性的变化。结果表明 ,随虫体发育 SDH,FE,ACP,AKP,ATPase活性升高 ,L DH,GDH,XOD无明显变化 ,未显示 G6 Pase活性。结果揭示随虫体生长发育糖类与脂类分解产生能量的代谢通路及物质转运途径增强 ,乳酸酵解、氨基酸分解、核苷酸分解途径无明显变化 ,虫体可能不具有糖异生作用。     

Neural activity triggers neuronal oxidative metabolism followed by astrocytic glycolysis

We have found that two-photon fluorescence imaging of nicotinamide adenine dinucleotide (NADH) provides the sensitivity and spatial three-dimensional resolution to resolve metabolic signatures in processes of astrocytes and neurons deep in highly scattering brain tissue slices. This functional imaging reveals spatiotemporal partitioning of glycolytic and oxidative metabolism between astrocytes and neurons during focal neural activity that establishes a unifying hypothesis for neurometabolic coupling in which early oxidative metabolism in neurons is eventually sustained by late activation of the astrocyte-neuron lactate shuttle. Our model integrates existing views of brain energy metabolism and is in accord with known macroscopic physiological changes in vivo.     

Vascular smooth muscle: aerobic glycolysis linked to sodium and potassium transport processes

Under aerobic conditions, glucose is primarily catabolized by vascular smooth muscle to lactate, in spite of an adequate oxidative capacity. Although this is often considered to be indicative of some nonspecific metabolic insufficiency, there is evidence that aerobic glycolysis is specifically coupled to sodium and potassium transport processes, whereas oxidative metabolism is couple to contracticle energy requirements.     

Regulation of blood glucose by hypothalamic pyruvate metabolism

The brain keenly depends on glucose for energy, and mammalians have redundant systems to control glucose production. An increase in circulating glucose inhibits glucose production in the liver, but this negative feedback is impaired in type 2 diabetes. Here we report that a primary increase in hypothalamic glucose levels lowers blood glucose through inhibition of glucose production in rats. The effect of glucose requires its conversion to lactate followed by stimulation of pyruvate metabolism, which leads to activation of adenosine triphosphate (ATP)-sensitive potassium channels. Thus, interventions designed to enhance the hypothalamic sensing of glucose may improve glucose homeostasis in diabetes.     

碳源对固定化费氏丙酸菌生产丙酸的影响研究

[目的]研究碳源对固定化费氏丙酸菌生产丙酸的影响.[方法]采用吸附-包埋结合法制备固定化费氏丙酸菌细胞,用于生产丙酸,研究了碳源（葡萄糖、乳酸钠和蔗糖）及其浓度对固定化细胞生产丙酸的影响.[结果]最适宜的碳源为乳酸钠,最适浓度为40g/L,丙酸产量13.03 g/L.[结论]试验考察了碳源对固定化费氏丙酸菌生产丙酸的影响,为费氏丙酸菌的开发利用提供了依据.     

糖皮质激素及灌注色氨酸对肉仔鸡下丘脑代谢物变化的影响

【目的】利用皮下注射人工合成糖皮质激素的方式模拟应激,通过核磁共振(NMR)技术研究应激及色氨酸对肉仔鸡下丘脑代谢状况的影响,为探明下丘脑食欲调控机制提供依据。【方法】10日龄AA肉仔鸡32只随机分为4组,早6:00禁食3h后,以2.0mg·kg-1BW剂量皮下注射地塞米松,同时灌注色氨酸(生理盐水溶解,500mg·kg-1BW),对照组分别皮下注射、灌服生理盐水,3h后取血浆及下丘脑。下丘脑用高氯酸萃取后进行核磁共振研究。【结果】通过1HNMR谱,发现应激改变了肉鸡下丘脑乳酸,葡萄糖,ATP,肌醇,3-羟基丁酸的相对含量;未检测到色氨酸信号的改变。【结论】NMR技术能够检测到应激状态下下丘脑代谢物的改变;应激状态下,ATP、葡萄糖和其它能量底物信号的改变可能参与了下丘脑对食欲的调控作用。     

Feedback inhibition of key glycolytic enzymes in liver: action of free fatty acids

Increasing concentrations of sodium octanoate were progressively inhibitory to the activities of glucokinase, hexokinase, phosphofructokinase, and pyruvate kinase. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases were also markedly inhibited. Other enzymes of carbohydrate metabolism such as lactate dehydrogenase, phosphohexose isomerase, and fructose-1,6-diphosphatase were not decreased. Among the key glycolytic enzymes, the inhibition of pyruvate kinase by the fatty acid was most marked. The biological significance of the inhibition of the key glycolytic enzymes is interpreted as a feedback inhibitory mechanism in regulation of fatty acid biosynthesis. The mechanism may function for rapid adaptation by which the organism can use the fatty acid level as a metabolic directional switch in decreasing glycolysis and turning on gluconeogenesis.     

Brain tryptophan hydroxylation: dependence on arterial oxygen tension

The accumulation of cerebral 5-hydroxytryptophan after decarboxylase inhibition was decreased in rats maintained at arterial O(2) tensions below 60 mm-Hg. In contrast, brain lactate was stable above 40 mm-Hg and brain adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate were unchanged above 30 mm-Hg. There was a linear correlation of brain 5-hydroxytryptophan accumulation to cerebral venous O(2) tension. Cerebral tryptophan hydroxylase appears to have a poor affinity for oxygen and to be affected by slight hypoxia. The resultant decreases in monoamine neurotransmitter metabolism may explain the behavioral changes of mild oxygen deprivation.     

铁棍山药POD特性及褐变抑制研究

以铁棍山药为试材,采用分光光度法,研究了与其褐变相关的过氧化物酶(POD)的特性以及抑制剂对POD活力的影响.结果表明:铁棍山药POD对愈创木酚的最适反应pH为5.0,温度为50'℃,在80℃下温育5 min基本失活,酶促反应的最佳底物为愈创木酚,且最适浓度为0.04 mol/L,Km值为 0.012mol/L;L-半...     

Temporal dynamics of nutrient balance,plasma biochemical and immune traits,and liver function in transition dairy cows

The objective of this study was to analyze the dynamics of nutrient balance, physiological biomarkers and comprehensive indexes associated with metabolism and function of organs in transition cows. Fourteen transition cows were used for this research. Dietary intake was recorded daily, and samples of the diet, venous blood and milk were collected for measurements. The balance values of net energy for lactation(NE_L), metabolizable protein(MP), and metabolizable glucose(MG) were calculated, and regression analysis and calculation of comprehensive indexes were performed. Accordingly, the prepartum cows presented positive balances of NE_L, MP, and MG, while severe negative balances were found during the postpartum period. Dynamic changes of energy metabolism, nutrient mobilization, liver function, anti-oxidative status and immune response, as indicated by blood biomarkers and modified comprehensive indexes, were out of sync with the calculated balance values, but they were closely related to the day relative to calving. Compared with the 21 d prepartum, the plasma concentrations of non-esterified fatty acids(NEFA) and β-hydroxybutyric acid(BHBA) were significantly increased around and after calving(P0.05), and similar variation tendency was observed for most of other parameters. The occurrence of parturition and the initiation of lactation were more responsible for the negative balances of nutrients in transition dairy cows. Although negative balances of NE_L, MP and MG were not observed using the assessment model, the nutritional strategies should be applied before calving, because metabolic adaptations had been validated during the prepartum period. In addition, it was plausible to conclude that the decline of hepatic metabolism, defense function and insulin sensitivity are critical causes of metabolic dysfunction.     

日粮不同能量和蛋白质水平对乌金猪肌肉组织能量代谢的影响

 为研究日粮不同能量和蛋白质水平对乌金猪肌肉组织能量代谢的影响,试验选取体重约15kg的乌金猪108头,随机分为6组,下设３个重复,每个重复６头,在15～30,＞30～60,＞60～100kg体重阶段分别饲喂不同能量和蛋白质水平日粮,能量水平为：高消化能（HE,1422MJ/kg）、中消化能 (ME,1289MJ/kg)和低消化能 (LE,1174MJ/kg),蛋白水平为：高蛋白质 (HP,18％,16％,14％）、中蛋白质（MP,16％,14％,12％）和低蛋白质（LP,14％,12％和10％）,在体重30,60,100kg体重时分批屠宰,取血液、肝脏及肌肉组织样品,测定血糖、肝糖原、肌糖原和肌肉中乳酸的含量及肌肉中乳酸脱氢酶、钠钾ATP酶（Na+K+ATP酶）和钙镁ATP酶（Ca2+Mg2+ATP酶）的活性。结果表明,乌金猪血糖、肝糖原、肌糖原和肌肉中乳酸的含量及肌肉中乳酸脱氢酶、Na+K+ ATP酶和Ca2+Mg2+ATP酶的活性随日粮能量和蛋白质水平的升高而升高;在60kg体重时,高能量和高蛋白质日粮组乌金猪上述各项指标均明显升高（P<0.05）,在100kg体重时,高能量和高蛋白质日粮组乌金猪血糖、肝糖原和肌糖原的含量及Na+K+ATP酶和Ca2+Mg2+ATP酶的活性明显高于低能量和低蛋白质组（P<0.05）。本次试验结果表明高能量和高蛋白质日粮（HE,1422MJ/kg和HP,18％）可促进乌金猪肝糖原和肌糖原的合成,肌肉组织中糖酵解途径供能增加,能量代谢加强。研究结果对阐明日粮不同营养水平对猪肌肉组织能量代谢的影响机制具有重要科学意义。     

Three-dimensional representation and analysis of brain energy metabolism

Quantitative autoradiography of brain glucose metabolism has been combined with digital image processing to represent the brain as a three-dimensional (3-D) reconstruction of brain energy use. Autoradiographs contain enormous amounts of potentially useful data, but conventional analyses, based on tedious manual methods, can sample and analyze only a small portion of this information. Computer 3-D reconstruction provides a mechanism for observing and analyzing all the data; therefore, a system of computer programs was developed for this purpose. The programs use digital imaging methods for image registration, superimpose whole brain data sets, and allow resampling of the 3-D data in arbitrary planes for pixel-by-pixel comparisons among multiple 3-D sets. These programs operate on the mathematical properties of the images alone, obviating the need for manual image alignment. Various statistical analyses can be applied to the data directly to study the patterns of metabolic changes in different experiments. The system is applied to data from experiments on the influence of injectable anesthetics on cerebral glucose metabolism.     

猪囊尾蚴体内发育过程中能量代谢变化规律的研究

研究猪囊尾蚴体内发育过程中能量代谢变化规律,应用分光广度法系统地测定了体内发育过程中猪囊尾蚴磷酸烯醇式丙酮酸羧激酶(PEPCK)、丙酮酸激酶(PK)、延胡索酸还原酶(FR)、异柠檬酸脱氢酶(ICD)、苹果酸酶(ME)活性的变化及葡萄糖(GLC)含量、乳酸(LAC)含量的变化。结果表明,随虫体发育PEPCK、FR、ICD成升高趋势,PK活性和PK/PEPCK比值呈下降趋势,GLC和LAC略有升高。提示随虫体生长发育PK代谢通路减弱而PEPCK通路增强。     

限氧与通氧条件下米根霉ADH突变株的碳代谢特性

【目的】乙醇脱氢酶（ADH）是米根霉发酵生产L-乳酸代谢途径中的支路关键酶，选育米根霉ADH突变株，降低ADH活力，可以提高乳酸转化率。【方法】利用亚硝基胍（NTG）诱变米根霉As3.3462，在含丙烯醇的YPD选择培养基上筛选获得ADH突变株，研究了突变菌株在限氧与通氧条件下的乙醇、乳酸、ADH与L-乳酸脱氢酶（LDH）的特性。【结果】 获得11株ADH突变株，其中mut-2突变株在通氧和限氧条件下对乳酸的转化率比出发菌株分别提高了84.6%和175%，而对乙醇的转化分别下降了39.5%和59.8%。mut-2突变株的最大ADH活力在通氧和限氧条件下均比出发菌株降低，而LDH活力在限氧条件下显著增加，通氧条件下变化不明显。【结论】氧气的供给对米根霉发酵产L-乳酸的产物组成比例影响很大，限氧发酵条件下ADH活力提高，乙醇积累。结果还表明，通过筛选米根霉ADH突变株，是获得L-乳酸高产菌株的一种简单快速的有效手段。     

超声波对猕猴桃片的渗糖效果及干燥能耗与品质的影响

【目的】研究不同的超声波工艺参数对猕猴桃片渗糖效果及干燥能耗与特征品质的影响,建立数学回归模型并优化工艺参数,为超声渗糖技术用于生产高品质、低能耗的猕猴桃片提供理论依据。【方法】试验以猕猴桃为原料,选取时间、温度、蔗糖浓度、超声声能密度为因素,以猕猴桃的固形物增加率（solids gain,SG）、水分损失率（water loss,WL）、单位能耗、可滴定酸、含糖量、色差（ΔE）、L*、a*、b*、硬度、黏性、弹性、黏聚性、胶黏性、咀嚼性、回复性、叶绿素保存率、维生素C保存率、可溶性固形物为指标,进行四因素Box-Benhnken响应面试验,利用因子分析筛选出评价猕猴桃片品质的特征指标,建立单位能耗及猕猴桃片特征指标的二次多项式回归方程模型,分析影响各指标的主次因素及因素间的交互作用,优化得出猕猴桃片超声渗糖工艺的最佳参数,并加以验证。【结果】猕猴桃片的品质特征指标分别为回复性、ΔE、含糖量、WL、可滴定酸、维生素C保存率;建立的猕猴桃片单位能耗和品质特征指标的回归模型具有统计学意义（P<0.05）。各因子对含糖量影响的大小依次是蔗糖浓度>时间>温度>声能密度,时间和温度、温度和蔗糖浓度、蔗糖浓度和声能密度的交互作用均为极显著,温度和声能密度的交互作用显著。各因子对WL影响的大小依次是时间>声能密度>蔗糖浓度>温度,时间和温度及时间和声能密度的交互作用显著。各因子对单位能耗影响的大小依次是蔗糖浓度>时间>声能密度>温度,温度和蔗糖浓度的交互作用显著。各因子对回复性影响的大小依次是时间>蔗糖浓度>温度>声能密度,蔗糖浓度和声能密度交互作用显著。各因子对ΔE影响的大小依次是蔗糖浓度>温度=声能密度>时间;各因子对可滴定酸影响的大小依次是时间>声能密度>蔗糖浓度>温度,时间和声能密度交互作用显著;各因子对维生素C保存率影响的大小依次是蔗糖浓度>温度>时间>声能密度。猕猴桃片超声渗糖工艺参数为：时间58 min、超声温度47℃、蔗糖浓度40 °Brix、超声声能密度0.7 W·mL ^-1,在此条件下猕猴桃片的单位能耗为18.15 kJ·g ^-1、回复性为0.172、ΔE为15.51、含糖量为35.03%、WL为27.85%、可滴定酸为1.58%、维生素C保存率为92.23%。 【结论】因子分析法能提取出评价猕猴桃片品质的特征指标。建立的二次多项式回归模型可分别用于分析和预测超声波处理参数对猕猴桃片的渗糖效果及干燥能耗与品质的影响。超声浸糖处理具有渗糖速率快、破坏小等优点,处理后的猕猴桃片单位能耗较低、质地品质较好,超声波处理可用于猕猴桃片的渗糖工艺。     

Excitatory effect of GABAergic axo-axonic cells in cortical microcircuits

Axons in the cerebral cortex receive synaptic input at the axon initial segment almost exclusively from gamma-aminobutyric acid-releasing (GABAergic) axo-axonic cells (AACs). The axon has the lowest threshold for action potential generation in neurons; thus, AACs are considered to be strategically placed inhibitory neurons controlling neuronal output. However, we found that AACs can depolarize pyramidal cells and can initiate stereotyped series of synaptic events in rat and human cortical networks because of a depolarized reversal potential for axonal relative to perisomatic GABAergic inputs. Excitation and signal propagation initiated by AACs is supported by the absence of the potassium chloride cotransporter 2 in the axon.     

Diazepam-binding inhibitor: a neuropeptide located in selected neuronal populations of rat brain

An endogenous polypeptide of rat brain has been identified that is capable of displacing 1,4-benzodiazepines and the esters of the 3-carboxylic acid derivatives of beta-carbolines from their specific synaptic binding sites. This polypeptide was termed diazepam-binding inhibitor (DBI). Previous studies have shown that DBI injected intraventricularly in rodents elicits "proconflict" responses and antagonizes the "anticonflict" action of benzodiazepines. An antiserum to this peptide, directed toward an immunodeterminant near its amino terminus, makes it possible to detect, measure, and study the neuronal location of this peptide in rat brain. In the rat cerebral cortex, DBI immunoreactivity is located in neurons that are not GABAergic (GABA, gamma-aminobutyric acid); in the cerebellum and hippocampus, however, it might be present also in GABAergic neurons.     

Hyperbaric oxygen: effects on metabolism and ionic movement in cerebral cortex slices

The incubation of slices of cerebral cortex under hyperbaric oxygen pressures from 1 to 10 atmospheres in the presence of radioactive glucose, pyruvate, succinate, fumarate, L-glutamate, and gamma-aminobutyric acid causes a marked diminution of tissue oxidative reactions. There is a simultaneous decrease in phosphocreatine and adenosine triphosphate, and a reduction of the apparent intracellular ionic gradients. The increase of lipid peroxides, measured directly, is attributed to the toxic effects of hyperbaric oxygen.     

无硫复合护色液对干制红富士苹果片中可滴定酸和可溶性糖含量的影响

[目的]研究红富士苹果干制过程中无硫复合护色液对果片中的可滴定酸和可溶性糖含量的影响。[方法]分别以一定浓度的氯化钠(0.7%)、氯化钙(0.6%)、柠檬酸(0.7%)、EDTA-2Na(0.16%)、异抗坏血酸钠(1.3%)和复合护色液(氯化钠1.0%、氯化钙0.6%、柠檬酸0.9%、EDTA-2Na 0.16%、异抗坏血酸钠1.6%)浸泡苹果片2 h,取出,沥干,放入恒温干燥箱中干制(60℃),考察不同护色剂对干制苹果片中可滴定酸和可溶性糖含量的影响。[结果]试验表明,不同护色剂均能显著抑制干制果片中的可滴定酸和可溶性糖含量的下降,其中以柠檬酸和无硫复合护色液对果片中可滴定酸含量下降抑制效果最好;以异抗坏血酸钠和无硫复合护色液对果片中可溶性糖含量下降抑制效果最好。[结论]研究认为,无硫复合护色液护色的主要机理是通过抑制果肉中的氧化酶活力和延缓抗氧化酶活力的下降来实现的。     

小麦低磷响应基因的筛选与表达分析

利用Affymetrix wheat microarray分析了郑麦9023在低磷和正常磷水培条件下,苗期根部基因在转录水平的差异。结果表明,1)筛选得到1 889个差异表达基因,其中1 298个上调表达,591个下调表达。2)基因功能分析显示,这1 889个基因参与了信号转导、蛋白存储、逆境胁迫、能量代谢、病程相关和其他与植物生长发育有关的过程。3)利用qRT-PCR对其中30个基因的表达情况进行了验证,显示与基因芯片结果基本相同的表达趋势。4)在低磷及磷恢复条件下,对其中5个候选基因(TaSPX3,TaIPS1.3,TaGST_Like,TaPDF19,TaG6PDH1_Like)在不同小麦品种中的表达进行分析,显示这5个基因受到低磷胁迫的强烈诱导,恢复供磷后表达显著回调。但是,这些候选基因在不同品种间横向表达趋势有差别,反应了不同基因型小麦对低磷胁迫的响应机制存在差异。预测这5个候选基因的功能涉及信号转导、氨基酸代谢、糖代谢、抗逆响应等重要的代谢或调控途径,在小麦应对低磷逆境机制中发挥重要作用。