羧肽酶B活力及稳定性研究

研究在不同pH,温度条件下,从猪胰脏中提取的羧肽酶B的稳定性,其活力最佳pH范围在7.5-8.5,最佳温度为55℃。     

pH对红褐斑腿蝗中肠主要蛋白酶活性的影响

为评价pH对红褐斑腿蝗Catantops pinguis (Stål)中肠蛋白酶活性的影响, 本文用3种专性底物测定了不同pH环境下蝗虫中肠类胰蛋白酶和类胰凝乳蛋白酶的活性。结果表明: 雄性红褐斑腿蝗中肠肠液的pH值为6.92±0.043, 雌性为7.03±0.054, 两性间差异不显著（P>0.05）。并且发现3种蛋白酶的最适pH值各不相同, 其中雌雄虫的强碱性类胰蛋白酶（以BAPNA为底物）最适pH分别为8.5和10.5; 雌雄虫的弱碱性类胰蛋白酶（以TAME为底物）最适pH分别为9.0和9.5; 而雌雄虫的类胰凝乳蛋白酶（以BTEE为底物）最适pH雌性为8.5, 雄性为8.0。统计结果显示, pH对红褐斑腿蝗中肠蛋白酶活性影响显著（P<0.01）, 两性间蛋白酶活性差异显著（P<0.01）。在最适pH情况下, 雌性的类胰蛋白酶活性高于雄性, 而类胰凝乳蛋白酶活性则是雄性高于雌性。在中肠pH范围内雌性比雄性具有更高的消化蛋白酶活性, 显示雌性具有较强的食物处理能力以摄取更多的营养物质为繁殖活动（孕卵）作准备, 而该种蝗虫最适pH范围较宽, 可能与其取食植物范围较宽有关。     

源自不同寄主的灰葡萄孢生物学特性的比较研究

本研究以分离自番茄、辣椒、草莓、葡萄的灰葡萄孢Botrytis cinerea为供试菌株,从生长温度、pH适应性、碳源、氮源营养利用等方面对不同寄主来源的灰葡萄孢菌株的生物学性状进行了比较研究。结果表明,5个不同寄主来源的灰葡萄孢菌株的菌丝生长温度范围相同,均为0-35℃;但它们的最适生长温度和分生孢子致死温度存在差异,来自和县番茄菌株HX12最适生长温度为20℃,分生孢子致死温度为47℃ 10min,其余最适生长温度均为25℃,分生孢子致死温度均为48℃ 10min;不同菌株在相同温度下的生长速率有显著差异。pH对不同寄主来源灰葡萄孢菌株菌丝生长的影响存在差异,来自长丰辣椒的菌株LJ菌丝在pH2-9的范围内均能生长,以在pH3-6.5时生长较快,pH6时最快;其余4个菌株在pH2-12的范围内均能生长,以在pH3-9时生长较快,pH6左右最快。不同碳源、氮源营养对灰葡萄孢菌株菌丝生长和分生孢子产生均有显著影响,不同寄主来源的菌株间在碳源、氮源营养利用差异均极显著。在相同碳源、氮源营养条件下,不同寄主来源的菌株的线性生长、菌丝干重和分生孢子产量均有显著差异。     

Studying the drift of in line pH measurements in cell culture

The culture of Chinese hamster ovary (CHO) cells to produce monoclonal antibodies (MAb) requires accurate measurement and control of pH. Unwanted pH drifts in cell culture can adversely affect process performance, product quality, and product yield. To measure and control pH throughout the length of a culture, most cell culture processes use traditional glass pH probes. Several variables can affect the design and performance of glass pH electrodes and lead to drift in the measurement. Understanding these variables and their effects on pH performance can lead to design improvements and potentially reduce the drift. In this study, a set of Rosemount Analytical glass pH probes was investigated in cell culture operations. Electrochemical properties of the probes were monitored throughout the experiments. Experimental results show that the glass membrane potential experiences the biggest change during cell culture operations. Changes in the reference electrode potential are small compared with the changes in glass membrane potential. The glass membranes are affected by the steam sterilization process and this is the main cause for drift in the probe sensing signal during cell culture operations. Steam sterilization can cause the potential of glass membranes to change by up to 15 mV (～ 0.25 pH units). This change in membrane potential can be observed as an undesirable pH drift in bioreactors.     

硫和pH对蛋白核小球藻光照产氢的影响

在有无硫及pH5.0-8.0下对蛋白核小球藻(Chlorella pyrenoidosa)光照产氢的影响进行了研究。结果表明,在持续光照(165μmolm-2s-1)条件下,从有硫培养液(TAP培养液)内叶绿素a含量、Fv/Fm值及ΦPSII值的变化表明蛋白核小球藻在pH6.0-7.0时生长最佳,生长旺盛易形成暂时的无氧环境而利于藻产氢。最高的产氢速率和总产氢量出现在pH7.0,分别是0.10mlmg-1chlh-1和1.39ml。从无硫培养液(TAP-S培养液)内叶绿素a含量、Fv/Fm值及ΦPSII值的变化表明蛋白核小球藻生长明显受抑制,形成的无氧环境持久,故产氢持久,总产氢量比有硫培养液内高。蛋白核小球藻在pH5.5培养液内的Fv/Fm值后期高于其他4种pH值的,表明潜在的PSII光化学效率高,在光照条件下产氢电子主要来源于PSII,故pH5.5的无硫培养液内藻的产氢速率和总产氢量最大,分别是0.58mlmg-1chlh-1和10.98ml。说明pH为5.5的无硫培养液是蛋白核小球藻产氢的最佳条件。     

温度及pH对隆线溞生长和生殖的影响

研究了隆线溞(Daphnia carinata)在不同温度(15、20、25、30℃)和pH(6、7、8、9、10)影响下的内禀增长率(rm)、周限增长率(λ)、平均世代周期(T)、净生殖率(R0)、平均寿命、第一怀卵日、平均生殖间隔期和总生殖量.结果表明,温度对隆线溞的生命参数有显著影响,30℃组的内禀增长率(rm)...     

长江口纹缟虾虎鱼早期发育对生态因子的适应性

纹缟虾虎鱼广泛分布于长江口水域,是许多水生动物的重要饵料,在长江口水生生态系统中具有重要地位.2007年在人工繁殖基础上系统研究了长江口纹缟虾虎鱼(Tridentiger trigonocephalus)胚胎与仔鱼的发育特征及其与温度、光照、pH等生态因子的关系.结果表明,温度上升时纹缟虾虎鱼胚胎发育速度加快,受精率与孵化率下降,17～21℃是纹缟虾虎鱼胚胎发育的适宜温度,胚胎发育有效积温模型为:N=3128.3/(T-4.36),温度系数Q10值为1.33～2.84;随着温度升高,仔鱼器官发育速度与卵黄囊被吸收速度加快,但存活率下降.不同光照周期中,长光照组胚胎比自然光照组与长黑暗组发育快,但孵化率低;仔鱼亦是长光照组比自然光照组与长黑暗组发育快.pH升高时纹缟虾虎鱼胚胎孵化率升高,发育速度加快;高pH组(pH 7.5～9.5)水体中仔鱼发育较快,活力较好,发育特征亦更加明显,畸形率较低.综合各项指标表明,长江口纹缟虾虎鱼早期发育的适宜生态条件为:温度17～21℃,每昼夜光照12h以上,pH 7.5～9.5.长江口生态环境变动可能会对纹缟虾虎鱼早期发育及其资源量产生一定影响.     

碱度和pH对西藏拟溞存活、生长和生殖的影响

在温度为16±0.5℃和盐度15.5±0.5的条件下,研究了碱度和pH对西藏拟溞（Daphniopsis tibetanaSars）存活、生长和生殖的影响。结果表明,西藏拟溞的24h半致死pH为4.18和10.84;48h半致死pH为4.37和10.71;24h和48h半致死碱度分别为529.43mmol/L和503.69mmol/L。西藏拟在培养液的pH7—8时,生长率和存活率显著高于其他各组。pH7时,西藏拟溞的内禀增长率最大,为0.3014/d。pH8时次之,为0.2924/d。西藏拟溞在各碱度组中的生长率和存活率差异不显著。碱度为11.9mmol/L时,西藏拟溞产幼前发育期最短,为18.70±0.65d。在碱度11.9和18.9mmol/L时,其产卵率为1.1671和1.1877,高于其他各组。西藏拟溞在碱度为7.54mmol/L组中的rm最高,为0.3425/d,其他各组的rm在0.2889—0.3276/d之间。西藏拟溞生存的最适pH为7—8,最适碱度为4.75—18.9mmol/L。     

碱度和pH对两品系蒙古裸腹溞(Moina mongolica Daday)存活、生长和生殖的影响

在温度为(25±0.5)℃,盐度为31.5±0.5的条件下,研究了碱度和pH对两品系蒙古裸腹溞的存活、生长和生殖的影响.结果表明,两品系蒙古裸腹溞在培养液的pH 6～8时,生长率和存活率显著高于其他各组;晋南品系的内禀增长率最大为0 5758 ind · d-1,内蒙品系的内禀增长率最大为0.5519 ind · d-1.碱度的实验表明,两品系蒙古裸腹溞在培养液的碱度为2.05到4.58 mmol · L-1时,生长率和存活率显著高于其他各组;晋南品系的内禀增长率最大为0.5573 ind · d-1,内蒙品系的内禀增长率最大为0.5376 ind · d-1.在相同的实验条件下,两品系体长的增长差异不大,但各生殖参数晋南品系大多高于内蒙品系.两品系蒙古裸腹溞存活的最适pH为6～8,最适碱度为2.05到4.58mmol · L-1,晋南品系对于碱度和pH的适应能力大于内蒙品系.     

消化酶在条石鲷成鱼体内的分布及pH对消化酶活力的影响

采用酶学分析方法研究了消化酶在条石鲷(Oplegnathus fasciatus)成鱼体内不同消化器官中的分布和pH对其消化酶活力的影响。结果表明,(1)蛋白酶活力为胃>后肠>中肠>前肠>肝,淀粉酶活力为前肠>中肠>后肠>胃>肝,脂肪酶活力为前肠>中肠>胃>后肠>肝,表明胃是消化蛋白类物质的主要场所,肠道在各种营养物质的消化中起重要作用,而肝中3种酶活力很低,可能在食物的消化中作用较小。(2)条石鲷胃的蛋白酶和淀粉酶的最适宜pH值分别为3.2和5.6,胃蛋白酶在强酸性条件下活力较高,而胃淀粉酶在弱酸性条件下活力较高;肝的蛋白酶和淀粉酶的最适pH是7.6,在中性条件下活性较高;肠的蛋白酶和淀粉酶的最适pH为6.6,在弱酸性条件下活力较高。     

pH值对厚颌鲂幼鱼的耗氧率及窒息点的影响

在密封式流水呼吸室内,对厚颌鲂Megalobrama pellegrini幼鱼在pH值分别为5.5、6.0、6.5、7.0、7.5、8.0和8.5试验用水条件下的耗氧率进行了测定.结果 显示:厚颌鲂幼鱼耗氧率存在明显的昼夜变化,白天高于晚上,下午高于上午,夜间变化不大.不同pH值的平均耗氧率为0.7135 mg/g · h,平均耗氧率最高是在pH7.5时,为0.8665 mg/g · h,平均耗氧率最低是在pH5.5时,为0.5397 mg/g · h.在密封式呼吸室内测定pH值在5.5、6.0、6.5、7.0、7.5、8.0和8.5试验用水条件下的厚颌鲂幼鱼的窒息点,分别为1.3920、1.3067、1.1547、1.0683、1.0933、1.1733和1.2331 mg/L,平均窒息点为1.2008 mg/L.     

pH与氨的交互作用对壶状臂尾轮虫(Brachionus urceolaris)种群增长、繁殖及存活的影响

观测了pH7—10之间（间隔1）与非离子氨氮（NH3-N）浓度分别为0．5、1、2、5mgNH3-N／L和10mg NH3-N／L水质条件下壶状臂尾轮虫（Brachionus urceolaris）种群的增长、繁殖和存活率。结果表明,在没有NH3-N存在的情况下,轮虫在pH7—10之间都能存活,pH7时种群的净增殖率、内禀增长率都最高,pH8时世代时间最长。在适宜的pH条件下（pH7、8）,NH3-N浓度小于2mg／L时,轮虫的存活曲线变化不大,繁殖率几乎不受影响;在NH3-N浓度达到5mg／L时,存活时间缩短,繁殖率明显下降;当NH3-N浓度达到10mg／L时,壶状臂尾轮虫在48～72h内死亡,且不产生幼体。在非适宜pH条件下加入NH3-N后,种群的内禀增长率变为负值,净增殖率明显下降,种群出现负增长。以上结果表明高pH与NH3-N的交互作用对轮虫种群的增长与存活具有严重的负影响。     

Proteomic analysis of the pH response in the fungal pathogen Candida glabrata

Micro-organisms must adapt to environmental change to survive, and this is particularly true for fungal pathogens such as Candida glabrata. C. glabrata is found both in the environment and in diverse niches in its human host. The ambient pH of these niches varies considerably, and therefore we have examined the response of C. glabrata to changes in ambient pH using a proteomic approach. Proteins expressed in C. glabrata cells growing at pH 4.0, 7.4 or 8.0 were compared by 2-DE, and 174 spots displaying reproducible and statistically significant changes in expression level were identified by peptide mass fingerprinting, thereby extending our 2-DE map of the C. glabrata proteome to a total of 272 identified spots. Proteins involved in glucose metabolism, the TCA cycle, respiration and protein synthesis were expressed at lower levels during growth at pH 7.4 and/or 8.0, whereas proteins involved in stress responses and protein catabolism were expressed at higher levels under these alkaline conditions. Our data suggest that C. glabrata perceives low pH as less stressful than higher pH. This contrasts with another opportunistic fungal pathogen of humans, Candida albicans.     

胞外pH降低对肺动脉平滑肌细胞膜上电压门控性钾通道的调节

目的：观察pH对大鼠肺动脉平滑肌细胞（PASMCs）钾电流的调控作用并探讨其机制。方法：用全细胞膜片钳技术记录在正常细胞外液和不同pH的灌流液中,PASMCs膜上电压门控性钾电流大小（Ikv）,并分析了其电生理学特性的改变。结果：①胞外pH降低可快速可逆性抑制Ikv。,与对照相比（pH7.4）,pH值为7.0、6.5、6.0时,＋60mV处的峰电流的抑制率分别为：16.93％±2.47％、33.03％±2.13％、41.59％±6.53％,电流一电压关系曲线右下移。②胞外pH为7.0、6.5、6.0时,使电压依赖性Gk-Em向去极化方向移动。同时使半激活电压增加。结论：在缺氧所致缺氧性肺血管收缩反应（HPV）的发生中,胞外pH的降低可参与对Ikv的调节,从而使细胞膜去极化,Ikv减小电压门控钙通道打开,平滑肌细胞收缩,这可能是缺氧导致HPV的机制之一。     

Factors Affecting the Salinity Tolerance of the Freshwater Cryptomonad Chilomonas paramecium

ABSTRACT. The capacity of the freshwater cryptomonad Chilomonas paramecium to develop a tolerance for seawater in the growth medium was investigated as part of a research program exploring potential microbial food sources for estuarine bivalve mollusks. By gradually increasing the percentage of estuarine seawater included in a freshwater culture medium over the course of 10 years, strains were obtained that tolerate from 16 to 32% seawater (highest salinity 10.5 ppt), achieving equivalent final densities with similar gross biochemical composition. However, after subculture in seawater-containing media for over 20 years, growth rates in more-saline media remained appreciably slower than in low-salinity media. Reduction of C. paramecium growth rate by seawater was found to be exacerbated in media with an initial pH of 3.5 as compared with pH 4.0–5.0, suggesting either a specific H⁺ effect upon metabolism of the medium carbon source (lactic acid) or a general cation effect upon nutrient uptake or cell metabolism. By contrast, depression of growth rates at high salinity was ameliorated by eliminating sodium-phosphate enrichments in growth media. This suggests that cations in the phosphate salt were contributing to cation-mediated growth inhibition. Results indicate a potential for C. paramecium , cultured in moderately saline media with no phosphate enrichments, to be used as a carbohydrate supplement for laboratory and hatchery feeding of estuarine bivalve mollusks.     

全子宫切除术对阴道菌群的影响

目的研究全子宫切除术后阴道菌群及pH的变化,寻求适当的治疗措施,以提高术后患者的生活质量。方法分别观察术后未发生阴道炎、发生老年性阴道炎及正常近龄妇女3组共90例,进行菌群分析、pH测定,并使用乳杆菌DM9811代谢物脂肪酸组分对发生老年性阴道炎者进行治疗。结果术后妇女检出各种菌的数量少,乳杆菌的数量更少,阴道内没有占绝对优势的菌种;发生阴道炎组乳杆菌数量下降更明显,葡萄球菌及大肠埃希菌数量相对增多。术后阴道pH在5.9~7.3,发生阴道炎组较未发生阴道炎组高;以乳杆菌DM9811代谢物脂肪酸组分阴道用药治疗老年性阴道炎,治愈率为82.14%。结论全子宫切除术后阴道乳杆菌数量下降,pH升高,易发生老年性阴道炎。治疗以乳杆菌DM9811代谢物脂肪酸组分阴道用药效果佳。     

New technology for the detection of pH

The measurement of pH is the most widely employed test for (bio-)chemical lab. Since the first use of glass electrode to detect pH, new techniques and methods have broaden the scope of pH detection. Metal/metal oxide, ion sensitive field-effect transistors (ISFET), fibre-optical techniques, nanotechniques, and conducting polymer techniques have been extensively developed. This review covers the various methods for pH detection. New development trends were discussed.     

Confocal pH Topography in Plant Cells — Acidic Layers in the Peripheral Cytoplasm and the Apoplast

The distribution of intracellular pH was studied in cultured cells of Gossypium hirsutum by con-focal pH topography using the fluorescent probe car-boxy SNARF1 and a ratio imaging procedure. The resulting pH maps can visualize pH differences with an accuracy of 0.1 unit in the investigated range between 7.5 and 5.6. They reveal the following characteristic features of the Gossypium cells: – the pH of the cytoplasmic core regions ranges from near 7.4 in younger to near 6.0 in older cells; – vacuoles show the expected acidity with pH < 5.6; – the cell wall/apoplastic region is acidic with a pH near 5.6 or below, especially in young, growing cells; – interestingly, acidic areas appear also at the periphery of the cytoplasm, i.e. beneath the plasma membrane. They remain stable in the presence of 5/μmol/I of the protonophore CCCP. Acidic layers of peripheral cytoplasm were also detected in protoplasts of Penicillium cyclopium, i.e. eukaryotic cells of simpler structure, which served as a reference object. This ronfirms earlier findings obtained with classical fluorescence microscopy and another fluoroprobe (fluorescein diacetate). Though additional experimental support is needed, low pH regions at the cytoplasm/plasma membrane interface should be considered a real contribution to the pH control of plant and fungal cells, facilitating e.g. the maintenance of cytosolic pH in acidic environments.     

不同pH条件下5种臂尾轮虫（Brachionus）的生殖代价

研究了5种臂尾轮虫(萼花臂尾轮虫、方形臂尾轮虫、壶状臂尾轮虫、十指臂尾轮虫和角突臂尾轮虫)在不同pH条件下(pH 5, 6, 7, 8, 9, 10)当前繁殖(mx)与未来存活(lx 1)、未来生殖(mx 1)和残余生殖价(V*x)的相关关系.结果表明,5种臂尾轮虫存活代价的相关系数在初始几个日龄组表现为正相关或负相关,在随后的大部分日龄组中,均表现为负相关,直至整个生命周期.相对于存活代价,5种臂尾轮虫繁殖代价和残余生殖代价的相关系数的变化幅度较大,但整体趋势仍就是大部分呈现负相关.因此可以推断,轮虫在不同pH条件下存在存活代价、繁殖代价和残余生殖代价.mx与lx 1对日龄组的回归分析有100%回归关系显著,mx与mx 1有97%回归关系显著,而mx与V*x有93%回归关系显著.因此推断,轮虫在不同pH条件下存活代价、繁殖代价和残余生殖代价的负相关性随着日龄组的增加而逐步增加.结果还发现,某些种类的轮虫(方形臂尾轮虫、壶状臂尾轮虫和十指臂尾轮虫)在胁迫的pH(酸性或碱性)条件下,其存活代价、繁殖代价和残余生殖代价较适宜pH(中性)条件下更为显著.     

pH和氨氮对橄榄蚶耐受性的影响

采用实验生态学方法,研究了pH和氨氮对橄榄蚶稚贝和成贝存活和耐受力的影响.结果表明:pH显著影响橄榄蚶稚贝和成贝的成活率,橄榄蚶稚贝适宜pH范闱为7.9～9.4,pH为8.5时存活最好,橄榄蚶成贝的适宜pH范围为5.2～9.4.氨氮浓度和毒性试验时间的相互作用显著影响橄榄蚶稚贝和成贝的成活率,氨氮浓度越高,其毒性越强.稚贝48 h、96 h的半致死浓度(TLm)为58.6 mg·L-1、50.0 mg·L-1,安全浓度(SC)为5.9 mg·L-1、5.0 mg·L-1、成贝48 h、96 h的TLm为618.7 mg·L-1、556.9 mg·L-1、SC为61.9 mg·L-1、55.7 mg·L-1.