蛋白质,纤维素和单宁酸对东方田鼠摄食的影响

食物选择性是动物对取食生境中现存的食物种类做出的选择,是一个复杂的生态适应过程,与动物自身生理状及环境中食物的可利用量密切相关。单宁酸、蛋白质和纤维素是影响植食性动物食物选择的重要因素。在控制其它营养因子的条件下,设置10%蛋白质+2.25%纤维素+3%单宁酸(食物1)/6%单宁酸(食物2)和20%蛋白质+4.51%纤维素+3%单宁酸(食物3)/6%单宁酸(食物4)4个处理组,通过自助餐式选择笼内的喂养实验,测定单宁酸、蛋白质和纤维素对东方田鼠食物选择的影响。结果表明,东方田鼠对3%单宁酸处理组食物摄食量显著高于对6%单宁酸处理组(P0.001);但东方田鼠对6%单宁酸食物摄食量依蛋白质浓度变化,在20%蛋白质处理组的摄食量显著高于10%蛋白质处理组(P0.05);在含3%单宁酸处理组中,纤维素成为影响东方田鼠摄食的主要因素,而当单宁酸浓度增加到6%时,纤维素和蛋白质对东方田鼠摄食影响差异不显著;总之,单宁酸、蛋白质和纤维素对东方田鼠的摄食都产生重要影响,单宁酸对东方田鼠食物选择的影响程度最大,纤维素次之,蛋白质对东方田鼠摄食的影响会随单宁酸浓度的升高而增大。     

用工业单宁酸生产精制单宁酸工艺的研究

五棓子单宁(Gallotannin)是中国五棓子(Chinese Gallnut)中主要成份之一,由此为原料制得的提取物,统称单宁酸(Tannic Acid),又名鞣酸。直接从五棓子用水浸出单宁溶液,经真空浓缩,再喷雾干燥制成粉状,此称为工业单宁酸,一般工业上使用能满足要求。但在医药、食品工业、化学分析上要求更高质量的单宁酸,一般工业用单宁酸质量不能满足其要求,必须使用工业用单宁酸进一步精制、提纯。关于精制提纯的方法,国外多用有机溶剂萃取的方法,国内有些厂多用离子交换树脂法,我们根据工厂需要对以工业单宁酸生产精制单宁酸的工艺进行了试验室的研究。     

单宁酸对甜菜夜蛾幼虫生长发育及酚氧化酶活性的抑制作用

采用摄食毒力法研究了单宁酸对甜菜夜蛾[Spodoptera exigua (Hübner)]幼虫生长发育的影响及毒力作用,并分析了单宁酸对甜菜夜蛾酚氧化酶的抑制动力学.结果表明,不同质量浓度单宁酸对甜菜夜蛾初孵幼虫具有较强的毒杀作用,对3龄幼虫的体质量以及蛹质量、化蛹及羽化过程也均有明显的抑制作用(P<0.05).随单宁酸质量浓度的提高或处理时间的延长,甜菜夜蛾初孵幼虫的校正死亡率逐渐增大,单宁酸的抑制生长效应逐渐增强,处理第7天,单宁酸对试虫的半致死浓度(LC50)为3.772 3 g·L-1;8 g·L-1单宁酸对3龄幼虫体质量增长的抑制率最高(35.09%);16 g·L-1单宁酸对蛹质量和羽化率的影响最明显.单宁酸能明显抑制甜菜夜蛾酚氧化酶的活力,且随单宁酸浓度的提高,酚氧化酶相对活力下降趋势明显趋缓,单宁酸对甜菜夜蛾酚氧化酶活性的半抑制浓度(IC50)为0.234 3 mmol·L-1;在加入不同浓度单宁酸的反应体系中,酚氧化酶的活力与酶液量呈明显的线性关系;不同浓度单宁酸对甜菜夜蛾酚氧化酶抑制作用的Lineweaver-Burk双倒数图为1组横轴截距不变的直线;另外,单宁酸和半胱氨酸均可将多巴醌还原为多巴,且还原量均随反应时间的延长而增加.研究结果说明,单宁酸对甜菜夜蛾酚氧化酶的抑制作用是可逆的,为典型的非竞争性抑制剂,抑制常数(Ki)为0.193 8 mmol·L-1;单宁酸对甜菜夜蛾酚氧化酶二酚酶的抑制作用与L-多巴氧化产物的还原有关.     

单宁酸体外抑制痘苗病毒感染活性的效果分析

目的:观察单宁酸体外抑制痘苗病毒(VACV)感染的效果,探讨单宁酸干扰病毒入侵宿主细胞膜脂的效应机制。方法:基于痘苗病毒细胞感染模型,在病毒吸附前、吸附后和吸附同时3种情况下分别添加单宁酸,采用中性红比色法检测单宁酸对VACV的抑制作用,利用荧光偏振法和流式细胞术分别测定VACV对细胞膜流动性和膜电位的影响及单宁酸的干预作用。结果:单宁酸以病毒吸附后及病毒吸附同时2种方式加入时可抑制VACV感染,半数抑制浓度(IC50)分别为8.7和13.1μg/m L,治疗指数(TI)分别为9.3和6.2;VACV感染可增加细胞膜流动性,单宁酸在病毒吸附后作用,可显著降低细胞膜流动性;VACV感染使细胞膜电位绝对值增大,单宁酸对VACV感染引起的细胞膜超极化状态没有明显影响。结论:单宁酸具有明显的体外抑制VACV感染宿主细胞的作用,其机制可能与拮抗因病毒感染所致的细胞膜流动性升高的膜脂干扰效应有关。     

根田鼠对食物单宁酸的解毒代价

在实验室条件下,测定了根田鼠对单宁酸的解毒代价。结果表明,在食物蛋白质为10％的条件下,摄食3％和6％单宁酸食物的根田鼠经尿液分泌的葡萄糖醛酸较对照组分别增加13．77％和38．80％;与对照组比较,在食物蛋白质为20％的条件下,摄食3％和6％单宁酸食物的实验个体尿液分泌的葡萄糖醛酸分别增加6．11％和22．25％。在食物蛋白质为10％时,用3％和6％单宁酸食物处理的个体,其尿液NH4^ —N含量较对照组个体分别增加51．69％和198．44％。在食物中蛋白质为20％时,摄食3％和6％单宁酸食物的试验个体,其尿液中的NH4^ —N含量分别较对照组高1．72％和74．19％。由此说明,单宁酸能显著增加根田鼠尿液葡萄糖醛酸分泌量,根田鼠尿液的NH4^ —N的含量随食物单宁酸增加而增高,从而增加动物机体对单宁酸的代谢价。     

单宁酸对布氏田鼠能量代谢的影响

为了解单宁酸对成年布氏田鼠(Lasiopodomys bandtii**)能量代谢和产热的影响,本文采用含0、3.3%和6.6%单宁酸浓度的食物饲喂布氏田鼠21 d,对其体重、基础代谢率、非颤抖性产热和能量收支等进行了测定。代谢率采用封闭式流体压力呼吸计测定;非颤抖性产热用皮下注射去甲肾上腺素诱导;能量摄人采用食物平衡法测定。结果发现:(1) 单宁酸食物对布氏田鼠的体重没有明显影响;(2)取食含6.6%单宁酸食物的动物的基础代谢率于第10 d高于对照组。20 d时,3组动物的基础代谢率没有显著差异;(3) 单宁酸食物对非颤抖性产热没有显著影响;(4) 食用含单宁酸食物的动物的摄人能和消化能于第10 d显著低于对照组,但第20 d时则差异不显著。这些结果表明:布氏田鼠的基础代谢率和能量摄入对单宁酸的反应具有时段性,短期内能量消耗增加,随着动物对食物的适应,生理功能恢复到正常水平。     

新疆紫花苜蓿单宁提取工艺优化探讨

目的:从新疆紫花苜蓿中提取单宁酸.方法:采用正交试验法研究新疆紫花苜蓿单宁酸的最佳提取工艺条件,考察了乙醇浓度、乙醇中盐酸的浓度、提取时间、及温度四因素对新疆紫花苜蓿单宁酸提取率的影响.结果:确立了新疆紫花苜蓿单宁酸最佳提取条件为:盐酸浓度2.5%,乙醇浓度70%,提取温度50℃,回流提取5h,在最佳提取工艺条件下,新疆紫花苜蓿中单宁提取量为2.15mg/g.     

单宁酸对根田鼠断乳幼体生长和存活的影响

在食物中含10％和20％蛋白质条件下,测定了单宁酸对根田鼠幼体在断乳后20d内的生长和存活的影响。结果表明,食物中含蛋白质为10％的条件下,摄食含3％和6％单宁酸食物的试验个体生长速率分别为-0．135g/d和-0．25g/d,食物利用效率均显低于对照组,断乳后20d内平均存活天数较对照组分别下降26．23％和49．36％。在食物蛋白质为20％的条件下,摄食含3％和6％单宁酸食物的试验个体生长速率分别为0．134g/d和-0．116g／d,摄食6％单宁酸食物的试验个体食物利用效率显低于摄食3％单宁酸食物的试验个体和对照组个体,断乳后20d内的平均存活天数较对照组下降39．41％,摄食3％单宁酸食物的试验个体较对照组略有下降,但不显。上述结果验证了单宁酸能显影响植食性小哺乳动物生长和存活的假设。     

用单宁酸作示踪剂观察上皮细胞间的紧密连接

运用单宁酸染色示踪技术是研究细胞膜和细胞膜特化结构与功能关系的一种新发展起来的技术。用戊二醛加单宁酸的混合液固定生物组织,能够提高各类细胞表面膜的电子密度和反差。冰冻复型技术是研究质膜结构的一种很好方法,结合单宁酸示踪技术,可进而了解膜上某些结构及其功能之间的关系。冰冻复型膜上显示:在胃和小肠粘膜上皮顶端相邻两上皮细胞之间以及近肝毛细胆管处组成紧密连接的网状索条层数多,排列紧密,此处紧密连接结构发育好,单宁酸不能通过这个部位;在肾近端小管上皮细胞,网状索条仅有1～2层,单宁酸能通过此部位不受阻挡,在生理条件下,有利于肾近端小管参与重吸收和对机体水盐代谢平衡的调节。     

极田鼠基础代谢率对单宁酸反应的格局

采用Kalabukhov-skvortsov封闭式流体压力计测定根田鼠基础代谢率对食物单宁酸的反应格局。在食物蛋白质为10％条件下,摄入3％单宁酸食物的根田鼠在第5天、10天和20天的基础代谢率分别较第0天增高10．94％、20．82％及23．54％;摄入6％单宁酸食物的根田鼠在第5天、第10天和第20天的基础代谢分别较第0天增高18．67％、29．07％及27．71％、当食物蛋白质为20％时,摄入3％单宁酸食物的根田鼠在第5天、第10天和20天的基础代率分别较第0天增高6．67％、10．63％及11．21％;摄入6％单宁酸食物的根田鼠在第5天、第10天和20天的基础代谢率分别较第0天增高9．01％、14．50％及16．09％。说明,食物单宁酸能显地增加根田鼠的基础代谢率,充分检验了单宁酸使植食性小哺乳动物基础代谢率增高的假设。     

The optimal depot fat composition for hibernation by golden-mantled ground squirrels (Spermophilus lateralis)

Golden-mantled ground squirrels (Spermophilus lateralis) are herbivores that hibernate during winter. Although little is known about the nutritional/physiological constraints on hibernation, numerous studies have demonstrated that increasing the amount of linoleic acid (a polyunsaturated fatty acid) in the diet enhances hibernation. This is probably because high linoleic acid diets reduce the melting points of the depot fats produced for hibernation which makes them more metabolizable at low body temperatures. This suggests that a major limitation on hibernation may be obtaining enough linoleic acid in the diet for proper hibernation. In all previous studies, however, the amount of linoleic acid in the diets of free-ranging animals was either not considered, or the range of dietary linoleic acid contents in the experiments was less than that of natural diets. It is thus not known whether the amount of linoleic acid available to hibernators under natural conditions actually limits their torpor patterns. A series of laboratory feeding and hibernation experiments were conducted with S. lateralis and artificial diets with different linoleic acid contents that were either below or above the linoleic acid content of the natural diet. The results demonstrated that when dietary linoleic acid contents are either below or above natural levels, hibernation ability is greatly reduced. Hibernation ability was reduced when the squirrels were maintained on a high linoleic acid diet probably by the production of toxic lipid peroxides in brown adipose tissues. The results indicate that there is an optimal level of dietary linoleic acid for proper hibernation, and this is equal to that of the natural diet. The amount of linoleic acid available in the diet thus does not limit hibernation under normal natural conditions.Abbreviations BAT brown adipose tissue - bm body mass - FA fatty acid - PUFA polyunsaturated fatty acid - T _a ambient temperature - T _b body temperature - WAT white adipose tissue     

Studies on the Metabolism of D-amino acid in Microorganisms

Several strains of bacteria belonging to genus Aerobacter were found to oxidize D-glutamate rapidly, while tbey show feeble oxidative activity toward the L-form even when they were grown in the medium containing DL-glutamate.

The isolation of L-glutamate, a natural amino acid, from its DL-form was achieved by the degradation of D-glutamic acid using one of these strains.

This may be the first observation on a natural amino acid obtained from the racemic one by the metabolic action of the organism.

A new enzyme, D-glutamic acid oxidase, which is responsible for D-glutamate degradation in this organism and differs from Krebs’ D-amino acid oxidase, has been postulated.     

Structure-activity relationship of lipid A: comparison of biological activities of natural and synthetic lipid A's with different fatty acid compositions

To investigate the structure-activity relationships, various biological activities, including pyrogenicity, lethal toxicity, elicitation of Shwartzman reaction, mitogenicity and tumor necrosis factor (TNF)-inducing activity, were compared among natural and synthetic lipid A's differing in fatty acid composition. In all these tests, natural lipid A's from Escherichia coli and Salmonella minnesota and synthetic LA-15-PP, which carries 3-hydroxy- and 3-acyloxy-tetradecanoyl groups at the 2, 3 and 2', 3' positions, respectively, showed the strongest activities among the tested lipid A's. In contrast, LA-16-PP, in which the amide-bound 3-hydroxytetradecanoic acid at position 2 of LA-15-PP is replaced by 3-hexadecanoyloxytetradecanoic acid, exhibited lower activity than LA-15-PP and natural lipid A's. Although LA-16-PP has been assumed to have a typical Salmonella lipid A structure (and, in fact, it has a structure corresponding to one of the components of Salmonella lipid A), the activity of this synthetic compound was not comparable to that of natural Salmonella lipid A. LA-17-PP, in which tetradecanoic acid is the sole fatty acid component, exhibited relatively strong mitogenicity and TNF-inducing activity, but very low pyrogenicity. The activities of LA-18-PP, which has ester-bound tetradecanoic acid and amide-bound 3-hydroxytetradecanoic acid, were lower than those of LA-17-PP. The results indicate that the differences in fatty acid composition of lipid A's have important influences on the biological activities studied.     

Phenolic compounds from the Mongolian medicinal plant Scorzonera radiata

Chromatographic separation of a crude extract obtained from aerial parts of the Mongolian medicinal plant Scorzonera radiata yielded fifteen natural compounds, including two new flavonoids and one new quinic acid congener, as well as four flavones and eight quinic acid derivatives, all of which are known natural compounds. The structures of the isolated compounds were elucidated on the basis of NMR (1H, 13C, COSY, HMBC, ROESY, and TOCSY) and mass spectrometric data. The antioxidant activities of the quinic acid derivatives were evaluated by the DPPH assay.     

First synthesis of racemic saphenamycin and its enantiomers. investigation of biological activity

The natural antibiotic saphenamycin, 6-[1-(2-hydroxy-6-methyl-benzoyloxy)-ethyl]-phenazine-1-carboxylic acid, was synthesized from saphenic acid using temporary allyl protection of carboxy and phenoxy functionalities. Resolution of racemic saphenic acid was performed by crystallization of the corresponding (-)-brucine diastereomeric salts and the absolute configuration of (-)-brucinium (-)-saphenate was determined by X-ray crystallography to have R-configuration. This also proved to be the configuration of natural saphenic acid. Enantiomers of saphenamycin were obtained from resolved saphenic acid and screened against a range of skin flora and resistant Staphylococcus aureus strains. Biological activities of saphenamycin enantiomers were compared with that of the synthetic racemate as well as earlier reported activities of saphenamycin isolated from natural sources. No significant difference was observed in activity of the enantiomers of saphenamycin, which revealed that the chirality of saphenamycin has no consequences for the antibiotic activity. Saphenamycin proved to be a potent antibiotic against fusidic acid and rifampicin resistant S. aureus strains showing MIC of 0.1-0.2 microg/mL.     

Reexamination of the structure of eumelanin

The generally accepted concept that the black melanin eumelanin is made mostly from 5,6-dihydroxyindole but not from 5,6-dihydroxyindole-2-carboxylic acid (DHIC) was reexamined by comparison of synthetic and natural eumelanins. The analytical methods used were elemental analysis and determination of the carboxyl group by acid treatment to yield CO2 and by permanganate oxidation to yield pyrrole-2,3,5-tricarboxylic acid. It was found that DHIC-derived monomer units comprise only approx. 10% of enzymically prepared dopa-melanins but as much as a half of intact, natural eumelanins. The results also show that dopa-melanins prepared at higher pH retain higher percentages of the carboxyl group of dopa and contain higher percentages of pyrrole units, and that melanins are decomposed to a significant extent on acid treatment, the method commonly used to isolate melanins from natural sources.     

The role of asparagine-linked carbohydrate in natural killer cell-mediated cytolysis

Chinese hamster ovary cell lines with specific lesions in the formation of glycoconjugates were tested for their sensitivity to lysis by interferon-boosted human natural killer cells. We report here that the type of asparagine-linked carbohydrate present on target cell glycoproteins determines their susceptibility to natural killer lysis. The targets tested were Chinese hamster ovary parent cells and Lec1, Lec2, and Lec8 mutants. Lec8 and Lec2 cells show an overall reduction of galactose and/or sialic acid in their glycoconjugates due to defects in the translocation of UDP-galactose and CMP-sialic acid, respectively. Due to a specific block in N-linked carbohydrate processing, Lec1 cells produce only high mannose-type oligosaccharides, but their glycolipids are identical to those of the parent. Both Lec2 and Lec8 mutants are more sensitive to natural killer lysis than the parent cells. This is consistent with their extensive reduction in cell surface sialic acid. Furthermore, Lec1 mutants are more susceptible to natural killer lysis than the parent cells. To confirm that the increased natural killer sensitivity of Lec1 cells was due to the modification of N-linked carbohydrate, parent cells were treated with swainsonine, a specific inhibitor of N-linked oligosaccharide processing. Swainsonine-treated parent cells are nearly as sensitive to natural killer lysis as the Lec1 mutants.     

Natural auto- and polyreactive antibodies differing from antigen-induced antibodies in the H chain CDR3

We describe three sets of natural (preimmune) polyreactive antibodies and Ag-induced antibodies that share the same VH-VL combinations. The amino acid homology in the VH and VL segments averaged 92%. These sets were found among 49 neonatal and adult natural mAb that were compared with 35 Ag-induced monoclonals produced during the memory response to phosphocholine (PC)-keyhole limpet hemocyanin. Both groups of monoclonals had been selected on the basis of a restricted fine specificity pattern, namely the ability to recognize PC-protein and p-nitrophenyl phosphocholine but not PC. All of the antibodies were tested for reactivity against a panel of 15 self and foreign Ag. Despite their common fine specificity as the basis for selection, 33/49 natural antibodies were poly/auto reactive whereas 0/35 Ag-induced antibodies had such poly/auto reactive properties. The natural antibodies were encoded by genes representing nine different VH families and several V kappa and V lambda families. There were a few replacement substitutions distinguishing the Ag-induced antibodies from the natural antibodies in each set; however, the most noteworthy difference was the extreme variability of CDR3 in the natural antibodies that differed in both length and amino acid sequence from each other and from Ag-induced antibodies. The results suggest that CDR3 of the H chain may play a critical role in distinguishing poly- from monospecific combining sites in natural and Ag-induced antibodies.     

天然吸附剂—壳聚糖吸附性能的研究

本文通过研究天然吸附剂—壳聚糖对古龙酸、缬氨酸、水杨酸和谷氨酸等物质的吸附性能,主要研究了吸附容量随时间变化,吸附容量与pH值的关系以及它们的饱和吸附容量,从而为这种天然吸附剂的应用提供了基础。     

Effect of phenols on natural killer (NK) cell-mediated death in the K562 human leukemic cell line

Cancer disease is a major cause of death in Western societies. Epidemiologically, antioxidant phenols have been associated with diminished incidence of cancer, while experimentally, they have cytotoxic effects on cancer cells. The aim of this study was to clarify whether natural antioxidant phenols render K562 human leukemic cells more susceptible to natural killer (NK) cell apoptosis and/or necrosis. K562 cells were pre-incubated with 7 different phenols (p-hydroxy benzoic acid, syringic acid, ferulic acid, p-coumaric acid, o-coumaric acid, gallic acid, and rutin) individually and afterwards targeted with NK cells at a ratio 1/5. Percentages of apoptotic and necrotic cells were assayed via flow cytometric analysis of annexin V and PI-stained cells. For the morphological assessment, cells were stained with acridine orange and ethidium bromide and were examined under a fluorescence microscope. Pre-treatment with gallic acid significantly rendered K562 cells more susceptible to NK cell-mediated necrosis, while pre-treatment with rutin significantly rendered K562 cells more susceptible to apoptosis. Gallic acid and rutin exert anticarcinogenic activity via the enhancement of K562 cell susceptibility to NK cell-mediated necrosis and apoptosis, respectively.