热暴露大鼠心肌细胞钙稳态及其调节机制的研究

本文观察了离体成年大鼠心室肌肌质网、线粒体Ｃａ＾２＋－ＡＴＰ酶活性和总钙含是到及原代培养乳腺心肌细胞＾４６Ｃａ摄取、活性钙调素相对含量、胞浆内游离钙浓度在不同温度热暴露４０ｍｉｎ后的变化。结果表明：热暴露后,心肌奖浆、肌质网及线粒体中的Ｃａ＾２＋－ＡＴＰ酶活发表 所下降,心肌肌质网及线粒体中的总钙含量亦有降低趋势,心肌细胞活性钙调素相对含量显著下降,＾４６Ｃａ摄取量及胞浆内游离浓度显著升高。提示,     

Polyamines, both common and uncommon, under heat stress in rice (Oryza sativa) callus

Enhanced production and accumulation of free and conjugated polyamines as well as increased activities of their biosynthetic enzymes in plants have been associated with heat stress. Perchloric acid-soluble free, as well as conjugated polyamines, and their metabolic enzymes were studied under 45°C heat stress in callus raised from heat-tolerant and -sensitive rice cultivars. The levels of free and conjugated polyamines, as well as arginine decarboxylase (EC 4.1.1.19) and polyamine oxidase (EC 1.4.34) activities were higher in tolerant than in sensitive callus under non-stressed conditions. Heat stress caused greater accumulation of free and conjugated polyamines in callus of the heat-tolerant cultivar N22 than in that of the heat-sensitive cultivar IR8. In particular, the uncommon polyamines norspermidine and norspermine were detected in cv. N22, which increased appreciably during stress, but they were not detected in callus of cv. IR8. Arginine decarboxylase and polyamine oxidase activities increased to a larger extent in N22 than in IR8 callus during stress, activities that were well correlated with the increased levels of common and uncommon polyamines. Increased levels of transglutaminase activity indicated the high titre of conjugated polyamines.     

蝎毒耐热蛋白对大鼠急性分离海马神经元兴奋性的影响

应用全细胞膜片钳记录技术在电流钳模式下观察经持续高温等特殊处理后分离纯化的30～50 kDa蝎毒耐热蛋白(scorpion venom heat resistant protein,SVHRP)(国家发明专利,专利号ZL01 106166.92)对急性分离大鼠海马神经元兴奋性的影响.结果发现SVHRP可致海马神经元兴奋性降低.神经元经1×10-2 μg/mL SVHRP处理后动作电位发放模式改变,发放频率减少.在52个受检细胞中,有45个细胞产生位相放电(占86.54%);7个细胞产生重复放电(占13.46%).在产生位相放电的45个细胞中,有8个细胞在SVHRP处理后仍可以诱发出位相放电(占17.78%);37个细胞在SVHRP处理后无法诱导出位相放电(占82.22%),SVHRP处理后动作电位的产生与处理前相比,有显著差异(P＜0.01,n=45);在产生重复放电的7个细胞中,在1×10-2μg/mL SVHRP作用后均不能再次诱发出重复放电,而是产生一个动作电位或不再产生动作电位,药物处理前产生的动作电位个数为14.57±1.00,SVHRP处理后产生动作电位的个数为0.57±0.20,二者之间有显著性差异(P＜0.01,n=7).1×10-4 μg/mLSVHRP处理后,诱发动作电位产生的基强度由(75.10±8.99)pA增加到(119.85±12.73)pA(P＜0.01,n=8);阈电位由(-41.17±2.15)mV升至(-32.40±1.48)mV(P＜0.01,n=8);动作电位峰值由(68.49±2.33)mV下降至(54.71±0.81)mV(P＜0.01,n=8).由于神经元超兴奋性被认为是癫痫发作的基本机制之一,因此上述结果表明SVHRP有可能通过降低海马神经元兴奋性发挥其抗癫痫作用,这为蝎毒药物的进一步开发提供理论依据.     

高温瞬时α化大米中可酶促水解α氨基氮含量的测定

经单因素和正交实验优化,高温瞬时α化大米的蛋白质酶促水解条件为:pH3.0,温度30℃,液固质量比为15,水解时间3 h,加酶量为2.0SAPU.g-1米粉。在该水解条件下测定不同处理条件下大米的酶促水解α氨基氮含量,揭示了其在高温瞬时α化过程中的变化规律,在一定程度上可用于指导生产。     

病毒感染中的“双刃剑”——热激蛋白70

热激蛋白70(heat shock protein,Hsp70)是目前最为受人们关注的一类蛋白质因子,从低等细菌到高等人类中普遍存在,它结构保守、功能多样。Hsp70像是生物有机体的"防弹衣",使生物体在饥饿、酷热、氧化、感染等条件下避开不利因素的攻击;同时,它也是病菌、病毒等攻击寄主时的"作案工具",所以我们可以称之为细胞的"双刃剑"。本文主要对Hsp70的结构以及病毒感染过程中的"双刃"作用情况进行了综述。     

Impact of substrates acclimation strategy on simultaneous biodegradation of hydrogen sulfide and ammonia

Three columns were differentiated with feeding mixture of H₂S and NH₃ (MFC), feeding NH₃ followed by H₂S (NFC), and feeding H₂S followed by NH₃ (SFC). Removal performance, biodegradation capacity and microbial community structures in the three columns were compared. The results show that NFC has a shorter acclimation period for the removal of NH₃ gas and nitrification than MFC. Under the high loading of H₂S and NH₃ at 164 and 82 g m⁻³ h⁻¹, respectively, NFC exhibited high removal efficiency of NH₃ (>95%) while the removal efficiencies were obtained at 63 and 75% in MFC and SFC, respectively. The removal of NH₃ gas in NFC was significantly attributed to nitrification (over 50%), while adsorption and chemical reaction contributed to the removal of NH₃ in MFC and SFC. The different biodegradation capacities of NH₃ could be due to the dissimilarity in the microbial population presented in each column.