北京鸭在产蛋前后、产蛋周期中及注射已烯雌酚后血浆脂蛋白、T_3,T_4的变化

前言 Griffin(1、2)等对内鸡的研究表明,肉鸡血浆中β—和前β—脂蛋白的含量与体脂的含量有关。血浆β—和前β—脂蛋白的含量与脂肪率之间存在正相关,与瘦肉率之间存在显著负相关,因此,血浆中β—和前β—脂蛋白的含量,有可能成为预测瘦肉率的生理指标。β—和前β—脂蛋白具有转运内源性甘油三脂和胆固醇酯的作用,即将肝脏中合成     

温胆汤对高脂血症大鼠及小鼠体内脂质代谢调节机理研究

目的 :探求温胆汤对实验动物体内脂质代谢调节作用的机理。方法 :采用腹腔注射蛋黄乳剂的方法建立急性高脂血症小鼠模型 ,观察温胆汤对急性高脂血症成年小鼠粪便脂质含量、血清总胆固醇 (TC)、血清总甘油三酯 (TG)、低密度胆固醇 (LDL c)含量、血清丙二醛 (MDA)含量、血清超氧化物歧化酶 (SOD)活性、肝脏总脂解酶(LA)活性、脂蛋白脂肪酶 (LPL)活性和肝脂酶 (HL)活性的影响 ;建立大鼠高脂血症模型 ,观察温胆汤对大鼠血脂(TC、TG)水平、总脂解酶 (LA)、脂蛋白脂酶 (LPL)和肝脂酶 (HL)活性 ,以及肝脏低密度脂蛋白受体 (LDLR)基因表达的影响。结果 :温胆汤可降低小鼠粪便脂质含量 ,显著降低急性高脂血症小鼠血清TC、TG、LDL c含量 (P <0 .0 5 ) ,温胆汤还可提高血清SOD活性 ,降低MDA含量 ,达到降低体内脂质过氧化程度的目的。同时 ,温胆汤可提高肝脏脂蛋白脂肪酶 (LPL)活性和肝脏总脂解酶 (LA) ,但对肝脂酶 (HL)活性无明显影响。在针对高脂血症大鼠的实验研究中发现 ,温胆汤能够显著抑制大鼠血清总胆固醇 (TC)、血清总甘油三酯 (TG)浓度 ,提高脂蛋白脂酶(LPL)和总脂解酶 (LA)活性 ,但对肝脂酶 (HL)活性无明显影响 ;逆转录聚合酶链反应 (RT PCR)实验显示高脂饲料能显著降低大鼠肝脏LDLRmRNA水平 ,温胆汤能显?     

北五味子木脂素对酒精性肝损伤小鼠免疫功能的影响

目的观察五味子木脂素对小鼠淋巴细胞亚群和自然杀伤细胞(NK细胞)的影响.方法应用五味子木脂素高、中、低3个剂量治疗酒精性肝损伤小鼠,联苯双酯对照,观察其对小鼠脏器系数、体液免疫功能、淋巴细胞增殖以及NK细胞活性的影响,利用流式细胞仪和MTT法检测其对淋巴细胞亚群、NK细胞的影响.结果五味子木脂素中剂量组胸腺、脾脏系数明显增加,与对照组比较差异具有统计学意义(P0.05);五味子木脂素中剂量组能显著降低CD8+水平,提高CD3+,CD4+水平及CD4+/CD8+比值,与对照组比较差异具有统计学意义(P0.05);五味子木脂素中剂量能提高NK细胞活性和T,B淋巴细胞增殖能力,与对照组比较差异具有统计学意义(P0.05).结论五味子木脂素能够增强酒精性肝脏损伤小鼠的免疫功能.     

辣椒素对高脂诱导小鼠 非酒精性脂肪性肝病保护作用研究

目的探讨辣椒素(Capsaicin)对高脂诱导非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)小鼠肝脏的保护作用.方法 C57/B6小鼠随机分为普通食物组(Chow)、高脂组(HF)和高脂诱导干预组(HF+Cap);8周后处死小鼠,计算小鼠体质量增长、腹围、肝脏和附睾旁脂肪质量,计算小鼠肝脏指数和脂肪指数;观察Cap对小鼠血清空腹血糖、总胆固醇(TC)、低密度脂蛋白(LDL)、高密度脂蛋白(HD-L)、甘油三酯(TG)、游离脂肪酸(FFA)含量的影响;检测丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、谷胱甘肽转移酶(GST)活性;不同组小鼠肝脏做HE染色,观察小鼠肝脏病理变化.结果 HF组小鼠体质量、腹围、肝脏和附睾旁脂肪质量远远高于Chow组(P0.000 1);HF+Cap可以减缓高脂诱导的小鼠体质量的增加(P0.01).与高脂组比较,HF+Cap组血清中总胆固醇(TC)、低密度脂蛋白(LDL)、甘油三酯(TG)、游离脂肪酸(FFA)含量下降明显(P0.05),高密度脂蛋白(HD-L)含量增加.ALT,AST,GST活性与高脂组比较HF+Cap组得到改善(P0.05);肝脏脂肪变性、炎症与坏死得到改善.结论辣椒素对高脂诱导的小鼠非酒精性脂肪性肝病具有明显的保护作用.     

血脂类代谢研究中的转基因动物模型

转基因疾病动物模型 ,通过不表达或过量表达的基因来表现各种疾病。脂质代谢是人体中的一种极为复杂的生理过程 ,在与脂质代谢有关的基因中 ,既有促进动脉粥样硬化形成的因素 ,也有降低动脉粥样硬化发病的成份。本文介绍了涉及脂质代谢有关的载脂蛋白 (Apo)类基因 ,如ApoE、ApoA、ApoB、ApoC ;相应的受体基因 ,如A型人清道夫受体SR A、SR B1和SR CD ;与脂质代谢有关的酶和转运蛋白的基因 ,如胆固醇脂转运蛋白 (CETP)、脂蛋白脂酶 (LPL)等几十种转基因动物模型及其特点 ,这些与血脂有关的转基因动物模型在研究发病机理、药物筛选…     

中年女性体脂百分比测量及其回归方程的优选研究

根据体脂百分比回归方程,正确了解中年女性的肥胖程度和健康状况.根据健身习惯将64名健康中年女性分为健身组和非健身组,然后分别测定其体脂百分比、身体围度及派生指标BMI和WHR,进行相关性分析、逐步筛选回归分析,最终优选出预测中年女性身体体脂百分比的回归方程.结果表明:健身组中年女性中WHR与体脂率的相关性(r=0.854)最高,BMI与体脂率的相关性(r=0.657)最低;非健身组中年女性中BMI与体脂率的相关性(r=0.877)最高,WHR与体脂率的相关性(r=0.753)最低,说明在用BMI、WC、HC、WHR判断肥胖时,对于健身组和非健身组的人群是有差异性的.研究建立了适合中年女性的全身体脂率的推算公式:健身组女性体脂百分比(Fat%):y=38.514×WHR-1.7043;非健身组女性体脂百分比(Fat%):y=-3.481+0.112×HC+0.943×BMI.使用单一的评价标准(BMI或WHR)来判断中年女性肥胖时,对于健身组和非健身组是有差异性的.以BMI、WHR及身体围度作为自变量,以中年女性体脂百分比为因变量建立回归方程,中年女性的体脂百分比可以方便有效地根据优选方程进行估算.     

NO对GA_3延缓蒜苔衰老的影响

实验采用GA3、SNP、GA3+L-NAME、GA3+Na2WO4、GA3+HB处理离体蒜苔基部,定期测定苔苞直径、可溶性总糖、抗氧化酶活性、膜透性、H2O2等指标,研究GA3、NO在蒜苔衰老细胞内含物转运中的生理作用.结果表明:GA3和NO均可抑制苔苞直径增大;提高超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)活性,顶部POD、CAT活性;抑制基部过氧化物酶(POD)、过氧化氢酶(CAT)活性、H2O2和可溶性糖含量下降以及膜透性的升高;清除NO或抑制内源NO来源的任何一条途径均对GA3和NO的作用结果有影响,由此表明GA3延缓蒜苔物质转运可能通过NO起作用.     

杏仁油对实验性高血脂大鼠肝脏中脂酶活性及脂肪含量的影响

以实验性高血脂模型大鼠为实验对象,设置3个杏仁油剂量(0.5,1,1.5 mL)组、高血脂组(HG)和对照组(CG),观察了不同剂量杏仁油对高血脂大鼠肝脏总脂解酶(LA)、肝脏脂蛋白脂酶(LPL)和肝脂酶(HL)活性以及肝脏脂肪含量的影响.结果表明,杏仁油高剂量组(HDG)和杏仁油中剂量组(HMG)大鼠肝脏中LA、LPL、HL活性均显著高于高血脂组(P<0.01或P<0.05),杏仁油低剂量组(HLG)大鼠肝脏中LA、HL活性显著高于高血脂组(P<0.05),杏仁油高、中剂量组大鼠的肝脏脂肪含量显著低于高血脂组(P<0.01).因此,杏仁油具有提高实验性高血脂大鼠肝脏脂酶活性以及预防和改善肝脏脂肪积累的作用.     

湖南省成年人体脂率预测公式的建立

目的:验证日本铃木-长岭公式和美国Brozek公式推测湖南省成年人体脂率是否有效,建立适用于湖南省成年人体脂率的预测公式,为湖南省成年人控制体重、预防超重和肥胖提供可靠的预检方法,并为建立适合我国国民体脂率的预测公式提供方法学依据.方法:随机抽取240名湖南省成年人验证日本铃木-长岭公式和美国Brozek公式推测湖南省成年人体脂率的有效性;采用等容量分层随机整群抽样方法,再抽取湖南省20-59岁成年人960名,每10岁为一个年龄段,采用多元线性逐步回归分析拟合过程中R的趋1线性论,R2的变异比率论,以及方差分析、回归系数检验、残差检验等建立湖南省成年人体脂率预测公式.另随机抽取240名湖南省成年人验证所建公式.结果:应用日本铃木-长岭公式和美国Brozek公式低估了湖南省成年人的体脂率.建立湖南省成年男性预测公式:％ BF20-29 =0.278×肩胛部皮褶厚度+0.296×上臂部皮褶厚度+0.231×腹部皮褶厚度+6.215;％BF30-39 =0.134×上臂部皮褶厚度+0.170×腹部皮褶厚度+0.228×腰围-1.180;％BF40-49=0.206×肩胛部皮褶厚度+0.267×上臂部皮褶厚度+0.220×腰围-3.018;％BF50-59 =0.244×腹部皮褶厚度+0.368×上臂部皮褶厚度+0.144×腰围+1.726.女性预测公式:％ BF20-29=0.205×上臂部皮褶厚度+0.479×腹部皮褶厚度+ 0.449×臀围-23.949;％BF30-39=0.373×上臂部皮褶厚度+0.214×腹部皮褶厚度+0.162×臀围+1.032;％BF40-49=0.168×肩胛部皮褶厚度+ 0.211×腹部皮褶厚度+0.395×臀围-13.720;％ BF50-59=0.415×上臂部皮褶厚度+0.393×腹部皮褶厚度+0.238×臀围+1.808.回代检验和交叉验证结果表明应用所建公式推测出的体脂率与BIA法、DEXA法直接测试出来的体脂率之间均无显著差异(P＞0.05),Kappa检验表明所建公式与DEXA法的超重与肥胖检出率一致性理想.结论:本研究所建立的推测湖南省成年人体脂率公式是可行且可靠的.     

乙烯利对烟草离体叶圆片衰老相关生理指标的影响

采用乙烯利、AVG和硝酸银处理烟草离体叶圆片,并测定其叶绿素和丙二醛含量以及超氧化物歧化酶和脂氧合酶活性。结果表明:乙烯利处理可以加速离体叶片叶绿素的解体;随着衰老进程的加速,组织体内MDA的含量先升高后下降;乙烯处理短期内可以提高SOD活性;LOX活性呈现先升高后下降的趋势。乙烯启动衰老进程是烟草烟片变黄的重要原因,乙烯处理可增加植物抗胁迫能力,同时乙烯与脂氧合酶活性可能关系不密切。     

Cloning and expression of a rat brain L-glutamate transporter.

Synaptic transmission of most vertebrate synapses is thought to be terminated by rapid transport of the neurotransmitter into presynaptic nerve terminals or neuroglia. L-Glutamate is the major excitatory transmitter in brain and its transport represents the mechanism by which it is removed from the synaptic cleft and kept below toxic levels. Here we use an antibody against a glial L-glutamate transporter from rat brain to isolate a complementary DNA clone encoding this transporter. Expression of this cDNA in transfected HeLa cells indicates that L-glutamate accumulation requires external sodium and internal potassium and transport shows the expected stereospecificity. The cDNA sequence predicts a protein of 573 amino acids with 8-9 putative transmembrane alpha-helices. Database searches indicate that this protein is not homologous to any identified protein of mammalian origin, including the recently described superfamily of neurotransmitter transporters. This protein therefore seems to be a member of a new family of transport molecules.     

CtBP/BARS induces fission of Golgi membranes by acylating lysophosphatidic acid

Membrane fission is essential in intracellular transport. Acyl-coenzyme As (acyl-CoAs) are important in lipid remodelling and are required for fission of COPI-coated vesicles. Here we show that CtBP/BARS, a protein that functions in the dynamics of Golgi tubules, is an essential component of the fission machinery operating at Golgi tubular networks, including Golgi compartments involved in protein transport and sorting. CtBP/BARS-induced fission was preceded by the formation of constricted sites in Golgi tubules, whose extreme curvature is likely to involve local changes in the membrane lipid composition. We find that CtBP/BARS uses acyl-CoA to selectively catalyse the acylation of lysophosphatidic acid to phosphatidic acid both in pure lipidic systems and in Golgi membranes, and that this reaction is essential for fission. Our results indicate a key role for lipid metabolic pathways in membrane fission.     

Molecular machinery for non-vesicular trafficking of ceramide

Synthesis and sorting of lipids are essential for membrane biogenesis; however, the mechanisms underlying the transport of membrane lipids remain little understood. Ceramide is synthesized at the endoplasmic reticulum and translocated to the Golgi compartment for conversion to sphingomyelin. The main pathway of ceramide transport to the Golgi is genetically impaired in a mammalian mutant cell line, LY-A. Here we identify CERT as the factor defective in LY-A cells. CERT, which is identical to a splicing variant of Goodpasture antigen-binding protein, is a cytoplasmic protein with a phosphatidylinositol-4-monophosphate-binding (PtdIns4P) domain and a putative domain for catalysing lipid transfer. In vitro assays show that this lipid-transfer-catalysing domain specifically extracts ceramide from phospholipid bilayers. CERT expressed in LY-A cells has an amino acid substitution that destroys its PtdIns4P-binding activity, thereby impairing its Golgi-targeting function. We conclude that CERT mediates the intracellular trafficking of ceramide in a non-vesicular manner.     

Cell-free expression of functional Shaker potassium channels.

The functional activity of ion channels and other membrane proteins requires that the proteins be correctly assembled in a transmembrane configuration. Thus, the functional expression of ion channels, neurotransmitter receptors and complex membrane-limited signalling mechanisms from complementary DNA has required the injection of messenger RNA or transfection of DNA into Xenopus oocytes or other target cells that are capable of processing newly translated protein into the surface membrane. These approaches, combined with voltage-clamp analysis of ion channel currents, have been especially powerful in the identification of structure-function relationships in ion channels. But oocytes express endogenous ion channels, neurotransmitter receptors and receptor-channel subunits, complicating the interpretation of results in mRNA-injected eggs. Furthermore, it is difficult to control experimentally the membrane lipids and post-translational modifications that underlie the regulation and modulation of ion channels in intact cells. A cell-free system for ion channel expression is ideal for good experimental control of protein expression and modulatory processes. Here we combine cell-free protein translation, microsomal membrane processing of nascent channel proteins, and reconstitution of newly synthesized ion channels into planar lipid bilayers to synthesize, glycosylate, process into membranes, and record in vitro the activity of functional Shaker potassium channels.     

Lipid packing sensed by ArfGAP1 couples COPI coat disassembly to membrane bilayer curvature

Protein coats deform flat lipid membranes into buds and capture membrane proteins to form transport vesicles. The assembly/disassembly cycle of the COPI coat on Golgi membranes is coupled to the GTP/GDP cycle of the small G protein Arf1. At the heart of this coupling is the specific interaction of membrane-bound Arf1-GTP with coatomer, a complex of seven proteins that forms the building unit of the COPI coat. Although COPI coat disassembly requires the catalysis of GTP hydrolysis in Arf1 by a specific GTPase-activating protein (ArfGAP1), the precise timing of this reaction during COPI vesicle formation is not known. Using time-resolved assays for COPI dynamics on liposomes of controlled size, we show that the rate of ArfGAP1-catalysed GTP hydrolysis in Arf1 and the rate of COPI disassembly increase over two orders of magnitude as the curvature of the lipid bilayer increases and approaches that of a typical transport vesicle. This leads to a model for COPI dynamics in which GTP hydrolysis in Arf1 is organized temporally and spatially according to the changes in lipid packing induced by the coat.     

Barttin is a Cl- channel beta-subunit crucial for renal Cl- reabsorption and inner ear K+ secretion.

Renal salt loss in Bartter's syndrome is caused by impaired transepithelial transport in the loop of Henle. Sodium chloride is taken up apically by the combined activity of NKCC2 (Na+-K--2Cl- cotransporters) and ROMK potassium channels. Chloride ions exit from the cell through basolateral ClC-Kb chloride channels. Mutations in the three corresponding genes have been identified that correspond to Bartter's syndrome types 1-3. The gene encoding the integral membrane protein barttin is mutated in a form of Bartter's syndrome that is associated with congenital deafness and renal failure. Here we show that barttin acts as an essential beta-subunit for ClC-Ka and ClC-Kb chloride channels, with which it colocalizes in basolateral membranes of renal tubules and of potassium-secreting epithelia of the inner ear. Disease-causing mutations in either ClC-Kb or barttin compromise currents through heteromeric channels. Currents can be stimulated further by mutating a proline-tyrosine (PY) motif on barttin. This work describes the first known beta-subunit for CLC chloride channels and reveals that heteromers formed by ClC-K and barttin are crucial for renal salt reabsorption and potassium recycling in the inner ear.     

UV-B辐射对极地雪藻Chlamydomonas nivalis的生物学效应

采用不同剂量的UV—B辐射极地雪藻,测定了致死率、色素含量、蛋白质和总脂含量以及自由基清除活性的变化．结果表明,UV—B辐射对极地雪藻具有一定的致死效应,UV-B辐射后雪藻细胞的叶绿素和类胡萝卜素含量增加,虾青素含量也显著提高．UV—B辐射后,极地雪藻基本生化成分的含量发生了较为明显的变化：蛋白质含量随辐射时间的延长而逐渐降低,总脂含量则逐步增加．经UV—B辐射培养以后,极地雪藻在有机溶剂系统中的自由基清除活性有所提高．     

Appearance of new variants of membrane skeletal protein 4.1 during terminal differentiation of avian erythroid and lenticular cells

The erythrocyte plasma membrane is lined with a network of extrinsic proteins, mainly spectrin and actin, which constitute a reticulum tethered to the intrinsic anion transport protein of the lipid bilayer through a linker protein, ankyrin. Protein 4.1 forms a stable ternary complex with spectrin and actin, thereby strengthening the reticulum and anchoring it directly to the lipid bilayer or to another intrinsic protein, glycophorin. It has been found recently that spectrin, ankyrin and protein 4.1 are not erythrocyte-specific; this has elucidated further the mechanisms of plasma membrane assembly and modelling during the differentiation of diverse tissues. We have shown previously that protein 4.1 in chickens is most abundant in erythrocytes and lens cells, but is scarce or absent from other spectrin-rich cell types. In addition, it exists as a family of related polypeptides showing differential expression in these two tissues, suggesting variant-specific functions. Here we show that the pattern of protein 4.1 variants changes during the terminal differentiation of erythroid and lenticular cells, with novel variants appearing in postmitotic cells. The accumulation of these variants may lead to the final stabilization of the plasma membrane skeletons of these cells.     

Complex lipid determines tissue-specific replication of Mycobacterium tuberculosis in mice

Tuberculosis is the leading cause of death in the world resulting from a single bacterial infection. Despite its enormous burden on world health, little is known about the molecular mechanisms of pathogenesis of Mycobacterium tuberculosis. Bacterial multiplication and concomitant tissue damage within an infected host, including experimentally infected mice, occurs primarily in the lungs-the favoured niche of M. tuberculosis. Although it has been proposed that the distinctive cell wall of M. tuberculosis is important for virulence, rigorous genetic proof has been lacking. Here, using signature-tagged mutagenesis, we isolated three attenuated M. tuberculosis mutants that cannot synthesize or transport a complex, cell wall-associated lipid called phthiocerol dimycocerosate (PDIM) which is found only in pathogenic mycobacteria. Two mutants have transposon insertions affecting genes implicated in PDIM synthesis; the third has a disruption in a gene encoding a large transmembrane protein required for proper subcellular localization of PDIM. Synthesis and transport of this complex lipid is only required for growth in the lung; all three mutants are unaffected for growth in the liver and spleen. This clearly shows that a lipid is required for M. tuberculosis virulence.     

Three distinct and sequential steps in the release of sodium ions by the Na+/K+-ATPase

The Na+/K+ pump, a P-type ion-motive ATPase, exports three sodium ions and then imports two potassium ions in each transport cycle. Ions on one side of the membrane bind to sites within the protein and become temporarily occluded (trapped within the protein) before being released to the other side, but details of these occlusion and de-occlusion transitions remain obscure for all P-type ATPases. If it is deprived of potassium ions, the Na+/K+ pump is restricted to sodium translocation steps, at least one involving charge movement through the membrane's electric fields. Changes in membrane potential alter the rate of such electrogenic reactions and so shift the distribution of enzyme conformations. Here we use high-speed voltage jumps to initiate this redistribution and show that the resulting pre-steady-state charge movements relax in three identifiable phases, apparently reflecting de-occlusion and release of the three sodium ions. Reciprocal relationships among the sizes of these three charge components show that the three sodium ions are de-occluded and released to the extracellular solution one at a time, in a strict order.