低氧训练对大鼠骨骼肌HIF 1α基因表达的影响

探讨不同低氧训练模式对机体骨骼肌HIF 1α mRNA水平和蛋白水平表达的影响。6周龄SD雄性大鼠120只,经3周适应性训练和力竭实验筛选出90只,随机分成9组：常氧安静对照组、持续低氧安静组、间歇低氧安静组、低住低练耐力组、高住高练耐力组、高住低练耐力组、低住高练耐力组、高住高练后复氧训练组和高住低练后复氧训练组。采用常压低氧仓在13.6%的氧体积分数下（相当于海拔3?500?m的氧体积分数）进行低氧训练,根据血乳酸-速度曲线确定大鼠常氧训练的强度为35?m/min,低氧训练的强度为30?m/min。低氧训练持续时间为6周,每周训练5?d。其中,在第4周末进行运动能力测试,第5周末进行力竭测试,在第6周末的最后一次运动后休息48?h后处死,取材。采用实时荧光定量PCR、免疫组化、Western blot等技术测试大鼠骨骼肌HIF 1α mRNA水平和蛋白水平表达水平的变化,以进一步探讨低氧训练对骨骼肌HIF 1α表达的适应机制。结果显示,与低住低练组相比,高住高练组和高住低练骨骼肌HIF 1αmRNA表达有显著性升高(P＜0.05);和常氧安静对照组相比,高住高练骨骼肌HIF 1αmRNA表达升高105%,有非常显著性差异(P＜0.01);高住高练后复氧训练1周,大鼠骨骼肌HIF 1αmRNA表达有非常显著性降低(P＜0.01),回到常氧安静对照组水平; 高住低练后复氧训练1周,大鼠骨骼肌HIF 1αmRNA表达有显著性降低(P＜0.05),回到常氧安静对照组水平。可得结论：高住高练、高住低练和持续低氧安静组骨骼肌HIF 1α表达都明显增强,而低住低练和低住高练变化不大,复氧训练后回到常氧安静水平。HIF 1α表达与低氧的程度和时间有明显的依存关系。     

缺氧胁迫小细胞团法选育高产黄酮苷悬浮细胞系

以银杏优良品种的种苗诱导愈伤组织,考察了B5,sH,MS,White4种培养基对银杏愈伤组织生长性状和黄酮苷合成能力的影响,采用缺氧胁迫小细胞团法从愈伤组织中筛选高产黄酮苷的细胞系,并对细胞系在悬浮培养时的条件进行了优化.结果表明TZG-1培养周期18d,生长指数为4.12,黄酮苷含量为1.25％,比愈伤组织提高了257.1％;Ms培养基有利于形成质地松软的愈伤组织,当培养基中NH4+与NO3-的浓度比为20.3/39.4或10.3/29.1,蔗糖质量浓度为30g/L或40g/L,pH值为5.6～6.0时,有利于细胞生长和黄酮苷合成.     

Pyruvate dehydrogenase kinase 4 expression is synergistically induced by AMP-activated protein kinase and fatty acids

Organs are flexible as to which substrates they will use to maintain energy homeostasis. Under well-fed conditions, glucose is a preferred substrate for oxidation. During fasting, fatty acid oxidation will become a more important energy source. Glucose oxidation is decreased by fatty acids, a process in which the pyruvate dehydrogenase complex (PDH) and its regulator pyruvate dehydrogenase kinase 4 (PDK4) play important roles. It is currently unknown how energy status influences PDH activity. We show that AMP-activated protein kinase (AMPK) activation by hypoxia and AICAR treatment combined with fatty acid administration synergistically induce PDK4 expression. We provide evidence that AMPK activation modulates ligand-dependent activation of peroxisome proliferator-activated receptor. Finally, we show that this synergistic induction of PDK4 decreases cellular glucose oxidation. In conclusion, AMPK and fatty acids play a direct role in fuel selection in response to cellular energy status in order to spare glucose. S. M. Houten, M. Chegary: These two authors contributed equally to this work. Received 11 July 2008; received after revision 26 January 2009; accepted 02 February 2009     

Coastal acidification in summer bottom oxygen-depleted waters in northwestern-northern Bohai Sea from June to August in 2011

Dissolved oxygen(DO) and pH in the central part of the Bohai Sea were surveyed in late June and late August,2011.During the June cruise,the bottom DO was in the range of 215-290 μmol-O2 kg-1(i.e.85%-115% of the saturation level),and the bottom pH was in the range of 7.82-8.04 on the total-hydrogen-ion scale.In August,however,both the bottom DO and the pH had significantly declined in the northwestern-northern near-shore areas,where the water depth was no more than 35 m.The lowest bottom DO was 100-110 μmol-O2 kg-1(only 44%-47% of the June DO values) in the northern near-shore area,where the bottom pH was 7.64-7.68 on the total-hydrogen-ion scale(0.16-0.20 units lower than the June pH value).The largest decreases in DO and in pH were observed in the northwestern near-shore bottom waters,corresponding to declines of 170 μmol-O2 kg-1(as high as 59% of the June DO value) and 0.29 pH units,respectively.The greatest pH decline of 0.29 pH units meant that the total-hydrogen-ion concentration doubled in the bottom waters from June to August.Based on field measurements of bottom DO/pH combined with a simplified model simulation,we suggest that respiration/remineralization-derived CO2 increased the acidity in the bottom oxygen-depleted waters of northwestern-northern near-shore areas in the Bohai Sea as a result of coastal red tides and/or marine aquaculture.This aquatic chemistry is suggested to be partially responsible for scallop-breeding failures in the northwestern Bohai Sea in summer 2011.     

缺氧胁迫及对贝类免疫系统的影响

人为压力源的强度和多样性日益增加已引发全球海洋生态系统中栖息地和生物多样性丧失。与全球变暖、海洋酸化类似,海域缺氧现象的频发使得缺氧现象成为重要的全球压力源。本文以贝类为研究对象,综述了缺氧的定义和等级、缺氧的原因,并集中探讨了缺氧胁迫对贝类免疫系统的影响,以期为贝类养殖和病害防治提供理论依据,并为我国贝类产业能够及时应对未来环境变化提供参考资料。     

生命的低氧适应——2019年度诺贝尔生理学或医学奖成果解析

 氧的利用和调节是高等生命赖以生存的基本条件，威廉·凯林、彼得·拉特克利夫和格雷格·塞门扎3位科学家因发现细胞感知和适应氧气供应的相关机制而获得了2019年度诺贝尔生理学或医学奖。他们发现低氧诱导因子1（hypoxia-inducible factors 1，HIF-1）广泛存在于急、慢性缺氧细胞中，是细胞适应低氧的重要转录因子。HIF-1水平受氧气含量的调节。高氧条件下，HIF-1被修饰进而降解；低氧条件下，HIF-1不被降解，并通过转录调节引起促红细胞生成素等低氧相关基因的表达。本文通过介绍HIF-1的发现和基本分子机制，探讨其在临床中的应用价值。     

温度对中华倒刺鲃静止代谢及低氧耐受的影响

为考查温度对鱼类静止代谢率及低氧耐受能力的影响,本研究以中华倒刺鲃（Spinibarbus sinensis）幼鱼为对象,分别在10、20和30℃条件下驯化2周,随后将实验鱼置于密闭呼吸室中测定静止代谢率,并通过“双线法”推出临界氧压（Pcrit）等相关参数。实验结果显示：随着温度的上升,中华倒刺鲃幼鱼静止代谢率（MO2rest）、Pcrit点所对应代谢率（MO2pcrit）以及临界代谢范围（MMS）均显著上升（p〈0.05）;MO2rest的温度系数（Q10）在10-20 ℃和20-30 ℃间分别为2.54和1.27。而中华倒刺鲃幼鱼Pcrit却不受温度变化的显著影响,表现出一定的保守性。研究表明,中华倒刺鲃幼鱼Pcrit随温度的变化趋势并不与 MO2rest的变化趋势相吻合,这提示随温度的改变中华倒刺鲃可能还启用了其他生理、生化和（或）行为学机制。     

Molecular basis and genetic improvement of economically important traits in aquaculture animals

Aquaculture has been believed to be a major Chinese contribution to the world. In recent 20 years, genome and other genetic technologies have promoted significant advances in basic studies on molecular basis and genetic improvement of aquaculture animals, and complete genomes of some main aquaculture animals have been sequenced or announced to be sequenced since the beginning of this century. Here, we review some significant breakthrough progress of aquaculture genetic improvement technologies including genome technologies, somatic cell nuclear transfer and stem cell technologies, outline the molecular basis of several economically important traits including reproduction, sex, growth, disease resistance, cold tolerance and hypoxia tolerance, and present a series of candidate trait-related genes. Finally, some application cases of genetic improvement are introduced in aquaculture animals, especially in China, and several development trends are highlighted in the near future.