Increase in activity during calorie restriction requires Sirt1

Sir2 (silent information regulator 2) is a nicotinamide adenine dinucleotide-dependent deacetylase required for longevity due to calorie restriction in yeast and Drosophila. In mammals, calorie restriction induces a complex pattern of physiological and behavioral changes. Here we report that the mammalian Sir2 ortholog, Sirt1, is required for the induction of a phenotype by calorie restriction in mice.     

Transgenic mice with a reduced core body temperature have an increased life span

Reduction of core body temperature has been proposed to contribute to the increased life span and the antiaging effects conferred by calorie restriction (CR). Validation of this hypothesis has been difficult in homeotherms, primarily due to a lack of experimental models. We report that transgenic mice engineered to overexpress the uncoupling protein 2 in hypocretin neurons (Hcrt-UCP2) have elevated hypothalamic temperature. The effects of local temperature elevation on the central thermostat resulted in a 0.3 degrees to 0.5 degrees C reduction of the core body temperature. Fed ad libitum, Hcrt-UCP2 transgenic mice had the same caloric intake as their wild-type littermates but had increased energy efficiency and a greater median life span (12% increase in males; 20% increase in females). Thus, modest, sustained reduction of core body temperature prolonged life span independent of altered diet or CR.     

Regulation of yeast replicative life span by TOR and Sch9 in response to nutrients

Calorie restriction increases life span in many organisms, including the budding yeast Saccharomyces cerevisiae. From a large-scale analysis of 564 single-gene-deletion strains of yeast, we identified 10 gene deletions that increase replicative life span. Six of these correspond to genes encoding components of the nutrient-responsive TOR and Sch9 pathways. Calorie restriction of tor1D or sch9D cells failed to further increase life span and, like calorie restriction, deletion of either SCH9 or TOR1 increased life span independent of the Sir2 histone deacetylase. We propose that the TOR and Sch9 kinases define a primary conduit through which excess nutrient intake limits longevity in yeast.     

卵母细胞发生阶段猪卵巢一氧化氮合酶的免疫组化定位

研究一氧化氮在猪胎儿卵母细胞发生中的作用,用免疫组化的方法检测了妊娠第33、40、46、54和61天的胎猪卵巢组织中内皮型一氧化氮合酶(eNOS)和诱导型一氧化氮合酶(iNOS)的分布。结果显示两者在各时期都有表达,染色都集中在卵巢中的上皮细胞、卵原细胞、卵母细胞、固缩坏死的卵原细胞和卵母细胞的胞质部分,eNOS在血管内皮细胞上也有表达。eNOS在妊娠33 d时表达很弱,妊娠46和61 d时活性相对较高;iNOS表达较强,且呈增强趋势。各时期核固缩或退化消失的卵原细胞或卵母细胞中,eNOS和iNOS呈强阳性染色;根据以上结果说明NO可能与胎猪卵母细胞发生有关。     

Suppression of aging in mice by the hormone Klotho

A defect in Klotho gene expression in mice accelerates the degeneration of multiple age-sensitive traits. Here, we show that overexpression of Klotho in mice extends life span. Klotho protein functions as a circulating hormone that binds to a cell-surface receptor and represses intracellular signals of insulin and insulin-like growth factor 1 (IGF1), an evolutionarily conserved mechanism for extending life span. Alleviation of aging-like phenotypes in Klotho-deficient mice was observed by perturbing insulin and IGF1 signaling, suggesting that Klotho-mediated inhibition of insulin and IGF1 signaling contributes to its anti-aging properties. Klotho protein may function as an anti-aging hormone in mammals.     

Mitochondrial biogenesis in mammals: the role of endogenous nitric oxide

Nitric oxide was found to trigger mitochondrial biogenesis in cells as diverse as brown adipocytes and 3T3-L1, U937, and HeLa cells. This effect of nitric oxide was dependent on guanosine 3',5'-monophosphate (cGMP) and was mediated by the induction of peroxisome proliferator-activated receptor gamma coactivator 1alpha, a master regulator of mitochondrial biogenesis. Moreover, the mitochondrial biogenesis induced by exposure to cold was markedly reduced in brown adipose tissue of endothelial nitric oxide synthase null-mutant (eNOS-/-) mice, which had a reduced metabolic rate and accelerated weight gain as compared to wild-type mice. Thus, a nitric oxide-cGMP-dependent pathway controls mitochondrial biogenesis and body energy balance.     

Requirement of NAD and SIR2 for life-span extension by calorie restriction in Saccharomyces cerevisiae

Calorie restriction extends life-span in a wide variety of organisms. Although it has been suggested that calorie restriction may work by reducing the levels of reactive oxygen species produced during respiration, the mechanism by which this regimen slows aging is uncertain. Here, we mimicked calorie restriction in yeast by physiological or genetic means and showed a substantial extension in life-span. This extension was not observed in strains mutant for SIR2 (which encodes the silencing protein Sir2p) or NPT1 (a gene in a pathway in the synthesis of NAD, the oxidized form of nicotinamide adenine dinucleotide). These findings suggest that the increased longevity induced by calorie restriction requires the activation of Sir2p by NAD.     

金钗石斛多糖对脂多糖诱导的小鼠腹腔巨噬细胞分泌TNF-α·NO的影响

[目的]研究金钗石斛多糖对脂多糖（LPS）诱导的小鼠腹腔巨噬细胞分泌肿瘤坏死因子-α（TNF-α）、一氧化氯（NO）的影响。[方法]用不同浓度金钗石斛多糖作用于小鼠腹腔巨噬细胞,LPS作为诱导剂,采用放射免疫法检测细胞培养液中TNF—α的含量,硝酸酶还原法测定细胞培养液中NO的含量,荧光法测定细胞内诱导型一氧化氮合酶（iNOS）的活性,实时PCR（real—time PCR）法测定TNF-α mRNA、iNOS mRNA的表达。[结果]与LPS组比较,金钗石斛多糖在50～400mg／L范围内可干预LPS对小鼠巨噬细胞的作用,使小鼠腹腔巨噬细胞TNF—α、NO合成减少,iNOS活性降低。TNF-α mRNA、iNOS mRNA的表达降低。[结论]金钗石斛多糖可改善LPS对小鼠腹腔巨噬细胞的作用,使TNF—α mRNA、iNOS mRNA的表达降低,TNF—α、NO合成减少,从而起到抗炎的作用、     

Rapamycin-induced insulin resistance is mediated by mTORC2 loss and uncoupled from longevity

Rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1), extends the life spans of yeast, flies, and mice. Calorie restriction, which increases life span and insulin sensitivity, is proposed to function by inhibition of mTORC1, yet paradoxically, chronic administration of rapamycin substantially impairs glucose tolerance and insulin action. We demonstrate that rapamycin disrupted a second mTOR complex, mTORC2, in vivo and that mTORC2 was required for the insulin-mediated suppression of hepatic gluconeogenesis. Further, decreased mTORC1 signaling was sufficient to extend life span independently from changes in glucose homeostasis, as female mice heterozygous for both mTOR and mLST8 exhibited decreased mTORC1 activity and extended life span but had normal glucose tolerance and insulin sensitivity. Thus, mTORC2 disruption is an important mediator of the effects of rapamycin in vivo.     

黄连素调节eNOS/NO保护软脂酸诱导的HUVECs损伤作用机制研究

目的：研究黄连素对软脂酸诱导人脐静脉内皮细胞（ HUVECs）损伤的保护作用,并初步探讨其作用机制.方法采用500μmol/L软脂酸培养HUVECs 24 h,建立内皮细胞损伤模型,MTT法观察黄连素对细胞存活率的影响;检测细胞培养上清液中一氧化氮（ NO）含量;RT-PCR法检测内皮型一氧化氮合酶（ eNOS） mRNA水平;Western blot方法检测eNOS和磷酸化eNOS蛋白的表达.结果与对照组比较,软脂酸组细胞存活率降低（ P〈0.05）,培养液中NO含量下降（P〈0.05）,细胞内eNOS mRNA水平、eNOS及磷酸化eNOS蛋白表达水平均显著下降（P〈0.01,P〈0.05）.与软脂酸组比较,黄连素组细胞存活率增加,培养液中NO含量明显提高（P〈0.05）,细胞内eNOS mRNA水平和磷酸化蛋白表达水平均显著提高（P〈0.01,P〈0.05）.结论黄连素对软脂酸引起的血管内皮细胞损伤有显著的保护作用,并可能与上调eNOS、促进NO生成有关.     

鹿茸保健饮品对氢化可的松所致小鼠肾阳虚症的影响

目的评定鹿茸保健饮品对氢化可的松所致小鼠肾阳虚症的影响。方法将小鼠分为氢化可松所致肾阳虚小鼠模型组及鹿茸保健饮品低剂量、中剂量、高剂量3个剂量组。每天灌胃生理盐水及鹿茸保健饮品1次,连续28d。分别以体重、生殖脏器指数、负重力竭游泳时间和血清、肾脏中一氧化氮含量为指标,观察鹿茸保健饮品对肾阳虚小鼠的作用效果。结果与模型组比较,鹿茸保健饮品各剂量组小鼠的体重明显增加（P〈0.05）;小鼠睾丸、睾丸-附睾、精液囊-前列腺的指数明显增加（P〈0.05）;负重游泳时间明显延长（P〈0.05）;运动后血清和肾组织中一氧化氮的含量明显升高（P〈0.05）。结论该鹿茸保健饮品具有促进性腺、附性腺的生长及补肾作用,同时具有明显的抗疲劳功效。     

中性粒细胞淋球菌感染模型的建立

目的 研究诱导型一氧化氮合酶（iNOS）及一氧化氮（NO）在中性粒细胞淋球菌感染模型中的表达。方法分离正常人外周血中性粒细胞,在10％胎牛血清DMEM培养液上培养3h,A组加入空白培养基,B组加入淋球菌菌液,随后在0、3、8、12h分别以实时定量荧光PCR测定iNOS mRNA表达,用镉还原法检测NO浓度。结果B组中iN08mRNA表达和NO水平均较A组升高（P〈0．01）,NO浓度在8h达到高峰。结论中性粒细胞淋球菌感染模型可成功模拟该菌体内微氧感染环境,可用于研究淋球菌致病机制。     

两种黄单胞病菌诱导水稻一氧化氮产生和防卫基因表达的比较研究

 【目的】阐明在不同黄单胞病菌诱导的水稻过敏性细胞死亡(HCD)中的一氧化氮(NO)信号途径及其作用机制。【方法】比较分析了在水稻细胞－番茄斑点病菌(Xanthomonas campestris pv. vesicatoria, Xcv)不亲和互作、水稻－白叶枯病菌(X. oryzae pv. oryzae, Xoo)亲和互作中NO的发生以及NO对水稻防卫基因诱导表达的影响。【结果】Xcv不仅诱导了NO的迸发、NOS活性及其NO合成相关基因(nos和nr)的表达，而且诱导了防卫基因(苯丙氨酸解氨酶基因pal、过氧化物酶基因pox和谷胱苷肽转硫酶基因gst)的表达；Xoo不诱导NO的迸发，抑制了NOS的活性、NO合成相关基因和防卫基因的表达；NO清除剂PTIO和Xoo显著地抑制了Xcv 对防卫基因表达的诱导作用。【结论】Xcv通过NO信号途径诱导了水稻防卫基因的表达和HCD；Xoo 通过NO抑制或解毒机制抑制了由NO介导的防卫基因的表达及其HCD的发生。     

白芷香豆素的镇痛机制初探

目的探讨白芷香豆素（Coumarin of Angelicae dahuricae,CAD）的镇痛作用机制．方法采用热板法,通过工具药观察CAD的镇痛作用与阿片受体和单胺类神经递质的关系;利用硝酸还原酶法检测CAD对甲醛所致伤害性疼痛模型小鼠血清一氧化氮（NitricOxide,NO）的含量．结果纳洛酮（5mg／kg）部分拮抗CAD（60mg／kg）的镇痛作用;利血平（4mg／kg）可以部分拮抗CAD（60mg／kg）的镇痛作用．CAD（30,60,120mg／kg）连续给药4d,使甲醛所致伤害性疼痛模型小鼠血清NO含量明显下降．结论CAD具有明显的镇痛,其镇痛作用与阿片受体和脑内单胺类神经递质有一定的关系．此外,明显减少NO的合成可能是其发挥镇痛作用的重要机制．     

北五味子木脂素和北五味子粗多糖对异丙肾上腺素诱导小鼠心室重构作用的研究

目的研究北五味子木脂素（Schisandra lignans,SCL）和北五味子粗多糖（Schisandra chinensis polysaccharides,SCP）对异丙肾上腺素（Isoproterenol,ISO）诱导小鼠心室重构的保护作用,并探讨其初步机制.方法采用连续10 d皮下注射ISO的方法诱导小鼠心室重构模型.小鼠随机分为对照组、ISO组、SCL低、中、高3个剂量组和SCP组,采用灌胃给药方法.实验结束后计算小鼠心脏重量指数;观察心肌病理形态学改变情况;HE染色后测定心肌纤维直径（MD）;分光光度法测定心肌组织中羟脯氨酸（HYP）含量、一氧化氮（NO）含量、一氧化氮合酶（NOS）活性、超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量.结果与对照组相比,ISO组小鼠心脏重量指数、HYP含量和MDA水平明显升高（P〈0.05或P〈0.01）,NOS和SOD活性及NO水平明显下降（P〈0.05或P〈0.01）;与异丙肾上腺素组相比,北五味子木脂素和北五味子多糖组能明显降低心脏重量指数（P〈0.05或P〈0.01）,改善心肌病理学变化,抑制心肌组织中羟脯氨酸含量,提高SOD活性,降低MDA含量,提高心肌中NOS活性和NO水平（P〈0.05,P〈0.01或P〈0.001）.结论北五味子木脂素和北五味子多糖对ISO诱导的小鼠心室重构具有抑制作用,其机制可能与提高NOS活性和NO水平、清除氧自由基、提高机体的抗氧化能力有关.     

HST2 mediates SIR2-independent life-span extension by calorie restriction

Calorie restriction (CR) extends the life span of numerous species, from yeast to rodents. Yeast Sir2 is a nicotinamide adenine dinucleotide (NAD+-dependent histone deacetylase that has been proposed to mediate the effects of CR. However, this hypothesis has been challenged by the observation that CR can extend yeast life span in the absence of Sir2. Here, we show that Sir2-independent life-span extension is mediated by Hst2, a Sir2 homolog that promotes the stability of repetitive ribosomal DNA, the same mechanism by which Sir2 extends life span. These findings demonstrate that the maintenance of DNA stability is critical for yeast life-span extension by CR and suggest that, in higher organisms, multiple members of the Sir2 family may regulate life span in response to diet.     

Nitric oxide represses the Arabidopsis floral transition

The correct timing of flowering is essential for plants to maximize reproductive success and is controlled by environmental and endogenous signals. We report that nitric oxide (NO) repressed the floral transition in Arabidopsis thaliana. Plants treated with NO, as well as a mutant overproducing NO (nox1), flowered late, whereas a mutant producing less NO (nos1) flowered early. NO suppressed CONSTANS and GIGANTEA gene expression and enhanced FLOWERING LOCUS C expression, which indicated that NO regulates the photoperiod and autonomous pathways. Because NO is induced by environmental stimuli and constitutively produced, it may integrate both external and internal cues into the floral decision.     

银杏叶复方对脾虚证小鼠肠道推进功能、 抗疲劳和抗氧化作用的影响

采用利血平复制脾虚证小鼠模型,观察银杏叶复方对脾虚证小鼠肠道推进功能、抗疲劳和抗氧化作用的影响。结果表明,与脾虚模型组相比,银杏叶复方能显著提高脾虚证小鼠肠道推进率和游泳时间(P<0.05),显著提高小鼠肝糖原(HG)含量(P<0.01)、血清过氧化物酶(POD)和过氧化氢酶(CAT)活力(P<0.05),显著减少血清中乳酸(LD)、尿素氮(BUN)和一氧化氮(NO)含量(P<0.05)。银杏叶复方是通过减轻血清中过量的一氧化氮对机体的损伤作用,参与调节肠道运动功能,提高了脾虚证小鼠肠道吸收功能;银杏叶复方的抗疲劳作用则与其降低运动后血清尿素氮含量,提高肝糖元的储备量,增强清除乳酸能力有关。     

猪TLR7基因胞外区部分片段的克隆、表达及其重组蛋白的纯化分析

[目的]获得高表达量的蛋白,为进一步研制单克隆抗体提供较好的免疫原,同时也可为TLR7胞外区该片断蛋白未知区域的结构和功能研究奠定基础。[方法]应用PCR技术从重组质粒pcDNA3．1／CT-GFP-pTLR7上扩增出编码猪TLR7基因胞外区N端第27—202位氨基酸序列,利用BamHI和HindⅢ酶切位点将其插入到原核表达载体PE130a中,重组质粒转化BL21（DE3）后,在不同条件下诱导表达。[结果]经SDS．PAGE分析表明,重组菌表达出约26kD的融合蛋白,并证实主要以包涵体形式表达,其最佳诱导表达条件是37℃、0．5mm01／LIPTG诱导6h,表达量可接近50％;纯化的重组蛋白免疫小鼠后,间接ELISA检测抗体效价,结果该蛋白免疫BALB／c小鼠效价达10^5．[结论]TLR7胞外区该片断重组蛋白具有很好的抗原性,可以作为单克隆抗体研制的免疫原。