Interaction Between Dietary Carbohydrate and Copper Nutriture on Lipid Peroxidation in Rat Tissues

The effects of the interactions between dietary carbohydrates and copper deficiency on superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and their roles in peroxidative pathways were investigated. Weanling rats were fed diets deficient in copper and containing either 62% starch, fructose, or glucose. Decreased activity of SOD was noted in all rats fed the copper-deficient diets regardless of the nature of dietary carbohydrate. However, the decreased activity was more pronouced in rats fed fructose. Feeding the fructose diets decreased the activity of GSH-Px by 25 and 50% in the copper-supplemented and copper-deficient rats, respectively, compared to enzyme activities in rats fed similar diets containing either starch or glucose. The decreased SOD and GSH-Px activities in rats fed the fructose diet deficient in copper were associated with increased tissue per-oxidation and decreased hepatic adenosine triphosphate (ATP). When the fructose in the diet of copper-deficient rats was replaced with either starch or glucose, tissue SOD and GSH-Px activities were increased and these increases in enzyme activity were associated with a tendency toward reduced mitochondrial peroxidation when compared to the corre-sponding values for rats fed fructose throughout the experiment Dietary fructose aggrevated the symptoms associated with copper deficiency, but starch or glucose ameliorated them. The protective effects were more pronounced with starch than with glucose.     

NDVI曲线与农作物长势的时序互动规律

利用气象卫星NOAA AVHRR资料,反演出农作物生育期内每日和旬度的NDVI数据,分析了NDVI时间曲线的波动与农作物生长发育阶段及农作物长势的响应规律,并以华北冬小麦为例,探讨了NDVI在冬小麦中生育期的积分值与农作物单产之间的相互关系。结果表明,利用长时间序列的NDVI数据,结合作物的物候历,可以实现作物长势的遥感监测和产量遥感估算。     

Influence of the Lipid Anchor Motif of N-Ras on the Interaction with Lipid Membranes: A Surface Plasmon Resonance Study

Ras GTPases play a crucial role in signal transduction cascades involved in cell differentiation and proliferation, and membrane binding is essential for their proper function. To determine the influence of the nature of the lipid anchor motif and the difference between the active (GTP) and inactive (GDP) forms of N-Ras on partitioning and localization in the lipid membrane, five different N-Ras constructs with different lipid anchors and nucleotide loading (Far/Far (GDP), HD/Far (GDP), HD/HD (GDP), Far (GDP), and HD/Far (GppNHp)) were synthesized. Using the surface plasmon resonance technique, we were able to follow the insertion and dissociation process of the lipidated proteins into and out of model membranes consisting of pure liquid-ordered (l_o) or liquid-disordered (l_d) phase and a heterogeneous two-phase mixture, i.e., a raft mixture with l_o + l_d phase coexistence. In addition, we examined the influence of negatively charged headgroups and stored curvature elastic stress on the binding properties of the lipidated N-Ras proteins. In most cases, significant differences were found for the various anchor motifs. In general, N-Ras proteins insert preferentially into a fluidlike, rather than a rigid, ordered lipid bilayer environment. Electrostatic interactions with lipid headgroups or stored curvature elastic stress of the membrane seem to have no drastic effect on the binding and dissociation processes of the lipidated proteins. The monofarnesylated N-Ras exhibits generally the highest association rate and fastest dissociation process in fluidlike membranes. Double lipidation, especially including farnesylation, of the protein leads to drastically reduced initial binding rates but strong final association. The change in the nucleotide loading of the natural N-Ras HD/Far induces a slightly different binding and dissociation kinetics, as well as stability of association, and seems to influence the tendency to segregate laterally in the membrane plane. The GDP-bound inactive form of N-Ras with an HD/Far anchor shows stronger membrane association, which might be due to a more pronounced tendency to self-assemble in the membrane matrix than is seen with the active GTP-bound form.     

瘤胃微生物与宿主互作及其日粮调控研究进展

瘤胃微生物与宿主间存在互作关系,宿主动物遗传信息影响瘤胃微生物,而瘤胃微生物变化也同样受到日粮原料、营养水平以及外源添加物质的调控。近年来,通过多组学技术分析瘤胃微生物与宿主关系及其内在机制已成为研究热点。综述了瘤胃微生物与宿主关系及受日粮调控作用研究进展,具体介绍了瘤胃微生物与宿主基因组关系,瘤胃微生物与动物生产性能关系,以及在日粮配置、益生菌益生元和植物次生代谢物添加等条件下对瘤胃微生物的影响;并对瘤胃微生物研究的发展趋势和应用前景进行了展望。     

磷脂组成对脱脂蛋白模型多肽与脂质体相互作用的影响

根据脱脂蛋白的脂结合序列合成了两个两亲性多肽Ａｍｐ１和Ａｍｐ２,在Ａｍｐ２在缬氨酸残基取代了Ａｍｐ１第４位的赖氨酸残基。用内源荧光谱发射峰的蓝移,包埋的钙氯黄素在脂质体中的渗漏,丙烯酰胺对多肽色氨酸残基的淬灭等手段比较了Ａｍｐ１与Ａｍｐ２与具有不同磷脂组成的脂质体的相互作用,并研究了温度的影响。     

Relationships between Dietary Fat,Body Fat,and Serum Lipid Profile in Prepubertal Children

KU, CHING YI, BARBARA A. GOWER, TIM R. NAGY, MICHAEL I. GORAN. Relationships between dietary fat, body fat, and serum lipid profile in prepubertal children. Obes Res. 1998;6:400–407. Objective : The purpose of the study was to test the hypothesis that dietary fat components were associated with the serum lipid profile independent of ethnicity, body fat, and fat distribution in prepubertal children. Research Methods and Procedures : Sixty-six children (45 African American and 21 Caucasian), aged from 4 to 10 years, were recruited into the study. Dietary total fat, saturated fat, monounsaturated fat, and polyunsaturated fat were estimated by averaging two 24-hour diet recalls. Fasting serum triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol were analyzed, and low-density lipoprotein cholesterol (LDL-C) was calculated by the method of Friedewald. Body composition and fat distribution were measured by dual energy X-ray absorptiometry and computed tomography. Results : Children in both ethnic groups tended to overreport their dietary intake relative to total energy expenditure by 18%. African American children consumed more energy from total fat (35.3% vs. 31.5%, p<0.05), saturated fat (13.7% vs 12.2%, p<0.05), protein (16.4% vs. 13.2%, p = 0.02), and less from carbohydrate (48% vs. 57.1%, p<0.01) than Caucasian children. There was no significant correlation between dietary fat and either serum lipids or body fat indices after adjusting for nonfat energy intake and total lean tissue mass. Total body fat (r = 0.32), subcutaneous abdominal adipose tissue (r = 0.39), and intraabdominal adipose tissue (r = 0.42) were positively related to serum triacylglycerol; these associations remained significant in a multiple linear regression model in which body fat indices were adjusted for ethnicity, total lean tissue, dietary total fat, and nonfat intake. Discussion : Our results do not support a link between dietary fat and serum lipids; instead, our data suggest that body fat may play a more important role than dietary fat in the course of cardiovascular disease development in prepubertal children.     

Influence of Nutrient Availability on the Interaction Between Spotted Knapweed and Bluebunch Wheatgrass

Centaurea maculosa (Lam.) (spotted knapweed) reduces wildlife and livestock habitat biodiversity and increases erosion. Nutrient availability to plants may be used to accelerate succession away from spotted knapweed. Early‐successional plant communities often have high nutrient availability, whereas late‐successional communities are often found on lower nutrient soils. We hypothesized that removal of nutrients would change the competitive advantage from spotted knapweed to Pseudoroegneria spicatum (bluebunch wheatgrass) (late seral). In two addition series matrices, background densities of Secale cereale (annual rye) and Elymus elimoides (bottlebrush squirreltail) (3,000 seeds/m²) were used to remove nutrients from the soil. In another set of addition series matrices, nitrogen (33 kg/ha) or phosphorus (33 kg/ha) were added to the soil. Nutrient analysis of soil and vegetation indicated that annual rye and bottlebrush squirreltail reduced nutrient availability in soils. In another matrix, neither a background density nor nutrients were added. Data were fit into Watkinson's curvilinear model to determine the competitive relationship between bluebunch wheatgrass and spotted knapweed. This allowed comparison of the equivalence ratios (C) generated from each addition series. The C parameters are the per‐plant equivalent of bluebunch wheatgrass or spotted knapweed and can be interpreted as the ratio of intra‐to‐interspecific competition. The C parameters are also the equivalence ratio of the number of spotted knapweed it takes to have equivalent effect on bluebunch wheatgrass or the number of bluebunch wheatgrass having the equivalent effect on spotted knapweed. Without nutrient manipulation, spotted knapweed was more competitive than bluebunch wheatgrass. The C for bluebunch wheatgrass was 0.17, indicating that 0.17 knapweed plants were competitively equivalent to one wheatgrass. Annual rye changed the competitive balance in favor of bluebunch wheatgrass (C = 9.9). Addition of nitrogen, phosphorus, or the mid‐seral species did not change the competitive relationship between the two species. This preliminary study suggests that succession from spotted knapweed to late‐seral bluebunch wheatgrass community may be accelerated by altering resource availability.     

The Interaction between Steroid Hormones and Lipid Monolayers on Water

The interaction of progesterone, testosterone, androsterone, and etiocholanolone with insoluble lipid films (cholesterol and saturated hydrocarbons containing either alcohol, ester, acetamide, phosphate, amine, or carboxyl groups) was studied. In addition to surface pressure and surface potential measurements of the surface films, radioactive tracers were used to measure the concentration of adsorbed steroid in the lipid films. In general, steroids form mixed films with the insoluble lipid films. Compression of the insoluble lipid films to their most condensed state leads to complete ejection of adsorbed steroid from the surface in all cases except with the amine, for which a small amount of steroid is still retained in the surface. Interactions between the steroids and insoluble lipids are primarily due to van der Waals or dispersion forces; there were no significant contributions from dipole-dipole interactions (except possibly with the amine). Specific interactions between cholesterol and the soluble steroids were not observed. Evidence suggests that low steroid concentrations influence structure of lipid films by altering the hydration layer in the surface film. In contrast to a specific site of action, it is proposed that steroid hormones initiate structural changes in a variety of biological sites; this model of steroid action is consistent with the ubiquity of many steroid hormones.     

Influence of Polycations on the Interaction Between Poliovirus Multistranded Ribonucleic Acid and HeLa Cells

In contrast to single-stranded viral ribonucleic acid (RNA), poliovirus multistranded RNA (RI-RNA) is poorly adsorbed to suspended HeLa cells in the absence of polycations. In the presence of 20 mug of diethylaminoethyl (DEAE) dextran per ml and other polycations, 90% or more of the RI-RNA is adsorbed to HeLa cells within 2 min at 37 C. However, only 30% of the RI-RNA label penetrates into the cells independent of the concentration of DEAE dextran applied. DEAE dextran is adsorbed almost quantitatively to HeLa cells within 3 min at 37 C. Most of the DEAE dextran remains bound to the cell membrane and available for binding of RI-RNA for 15 min at 37 C.     

Short‐Term Effects of Dietary Fatty Acids on Muscle Lipid Composition and Serum Acylcarnitine Profile in Human Subjects

In cultured cells, palmitic acid (PA) and oleic acid (OA) confer distinct metabolic effects, yet, unclear, is whether changes in dietary fat intake impact cellular fatty acid (FA) composition. We hypothesized that short‐term increases in dietary PA or OA would result in corresponding changes in the FA composition of skeletal muscle diacylglycerol (DAG) and triacylglycerol (TAG) and/or the specific FA selected for β‐oxidation. Healthy males (N = 12) and females (N = 12) ingested a low‐PA diet for 7 days. After fasting measurements of the serum acylcarnitine (AC) profile, subjects were randomized to either high‐PA (HI PA) or low‐PA/high‐OA (HI OA) diets. After 7 days, the fasting AC measurement was repeated and a muscle/fat biopsy obtained. FA composition of intramyocellular DAG and TAG and serum AC was measured. HI PA increased, whereas HI OA decreased, serum concentration of 16:0 AC (P < 0.001). HI OA increased 18:1 AC (P = 0.005). HI PA was associated with a higher PA/OA ratio in muscle DAG and TAG (DAG: 1.03 ± 0.24 vs. 0.46 ± 0.08, P = 0.04; TAG: 0.63 ± 0.07 vs. 0.41 ± 0.03, P = 0.01). The PA concentration in the adipose tissue DAG (µg/mg adipose tissue) was 0.17 ± 0.02 in those receiving the HI PA diet (n = 6), compared to 0.11 ± 0.02 in the HI oa group (n = 4) (P = 0.067). The relative PA concentration in muscle DAG and TAG and the serum palmitoylcarnitine concentration was higher in those fed the high‐PA diet.     

食草动物与植物的相互关系

动植物相互作用是决定动植物群落结构的重要因素[50 ] 。动物从多方面和多层次影响植物 ,最后都反映到植物群落结构的变化。而变化的植物群落又从各方面影响动物的生理、行为、种群特征、分布、种间关系等方面 ,最终反映到动物群落水平层次的改变 ,所以对动物群落与植物群落关系及机理的研究是个内容十分丰富的重要领域。1　食草动物的牧食作用对植物的影响食草动物的牧食作用 ,常使植物形态和结构发生变化 ,如导致植株的“矮化”或“匍匐化”,增加剌结构和机械结构 ,以抵御进一步被牧食[42 ] 。一定强度的牧食会加速植物光合作用强度 ,从而…     

Favorable Changes in Lipid Profile: The Effects of Fasting after Ramadan

Aims

We assessed the effect of fasting during Ramadan on blood pressure (BP), body weight, plasma lipid, and lipoprotein variables among healthy normal individuals.

Methods

102 (68% male) multi-ethnic volunteers; mean age ± SD (38.7±10.5 years) were randomly recruited in Al-Ain, United Arab Emirates (UAE), to be investigated before Ramadan, one day after the end of Ramadan, and four weeks after Ramadan. Anthropometric, demographic, fasting plasma total cholesterol (TC), triglyceride (TG), and high density lipoprotein–cholesterol (HDL-C) were measured by standard methods, and Low density lipoprotein-cholesterol (LDL-C) was calculated using Friedewald’s formula.

Results

65 subjects completed the study. We found significant and beneficial changes in systolic blood pressure (SBP), body weight, waist circumference (WC), TG, HDL-C and LDL-C, at the end of Ramadan, but not in TC. Further, there was a progressive and significant increase and decrease in HDL-C and LDL-C levels, respectively, four weeks after Ramadan.

Conclusions

We observed significant improvements in HDL-C, and LDL-C levels even after four weeks post Ramadan. Ramadan-like fasting may be considered for more effective lipid and lipoprotein control.     

The Impact of Dietary Iodine Intake on Lipid Metabolism in Mice

The present study has been designed to investigate the impact of dietary iodine intake on lipid metabolism in mice, including iodine deficiency and iodine excess. Different amounts of iodine mixed in the drinking water were continuously administered to mice. The body weights and the levels of urinary iodine were measured 8 months after the treatment. Thyroid hormones in the serum were detected by chemiluminescence immunoassay. Serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol and low-density lipoprotein cholesterol (LDL-C) were determined enzymatically by automatic analyzer. Results showed that the urine iodine concentrations paralleled the amounts of iodine intakes. No statistical differences of body weights among different groups were found. The levels of thyroid hormones were dramatically decreased in iodine deficiency while no significant differences were found between iodine excess groups and normal iodine group. In iodine deficiency groups, the levels of TG, TC, and LDL were increased at varying degrees. In iodine excess groups, the levels of TG in the male mice and the levels of TC in the female mice were much lower than normal iodine group. In conclusion, dietary iodine intake may affect the metabolism of serum lipids. Hypothyroid function induced by iodine deficiency may be responsible for the changes of lipids. Higher iodine intake might benefit lipid metabolism.     

食管组织和外周血中代谢和DNA修复相关基因的表达谱分析

目的:研究代谢酶和DNA修复相关基因在食管组织和外周血中的表达谱.方法:收集93例淮安地区食管癌病例的食管癌旁正常组织和外周血,采用实时荧光定量RT-PCR方法定量分析食管正常组织和外周血中的代谢酶和修复酶共计11个基因的mRNA水平.结果:11个代谢酶和修复酶基因在食管组织和外周血的表达水平有明显差异,食管组织中GSTPI＞NQOI、MGMT＞hMLH1、hMSH2、hOGG1、XRCC1、XPD,XPA、CYP2E1＞MTHFR;在外周血中GSTP1＞hMLH1、hMSH2、XPA、MGMT＞hOGG1、NQO1、CYP2E1、XRCC1、XPD＞MTHFR.食管组织基因表达水平与外周血相应基因的表达之间未发现有统计学意义的直线相关关系.结论:代谢酶和修复酶基因在食管组织和外周血的表达谱相似,但基因表达水平有差异,本分析为这些基因的研究提供了基础数据的支持.外周血和食管组织在肿瘤易感性和肿瘤发生相关的生物标志物研究中具有不同的应用价值.     

扬子鳄生活习性与环境温度的关系

１９８８￣１９９５年,每天观察扬子鳄的生活行为,并测量气、水温度,经过多年的重复观测,发现扬子鳄的生活习性与环境温度间存在着紧密关系：每年１０月下旬至次年４月底,鳄处于冬眠期,旬平均温度幅度在３￣１８℃间在至１０月下旬为采食期,旬平均温度幅度在２０￣３２℃间;５月下旬至９月下旬鳄处于繁殖期,旬平均温度幅度在２４￣３２℃间。据此总结出扬子鳄年生活周期循环规律图,并认为扬子鳄的生活及生理机能受气候温度