According to the instantaneous growth rate (dN/dt) of E. coli CVCC249 growing in batch culture, the entire growth progress was distinguished into four phases: accelerating growth phase, constant growth phase, decelera...According to the instantaneous growth rate (dN/dt) of E. coli CVCC249 growing in batch culture, the entire growth progress was distinguished into four phases: accelerating growth phase, constant growth phase, decelerating growth phase; declining phase, in each of which obvious variation in physiological; biochemical properties was detected, including total DNA, total protein,; MTT-dehydrogenase activity, etc., that led to difference in their antibiotic susceptivity. Antibiotic susceptivity of the population sampled from each phase was tested by Concentration-killing Curve (CKC) approach following the formula N=N 0/{1+exp[r·(x-BC 50)]}, showing as normal distribution at the individual cell level for an internal population, in which the median bactericidal concentration BC 50 represents the mean level of susceptivity, while the bactericidal span BC 199=(2lnN 0)/r indicates the variation degree of the antibiotic susceptivity. Furthermore, tested by CKC approach, the antibiotic susceptivity of E. coli CVCC249 population in each physiological phase to gentamicin or enoxacin was various: susceptivity of the population in the constant growth phase; declining phase all increased compared with that in the accelerating growth phase for gentamicin but declined for enoxacin. The primary investigations revealed that the physiological phase should be taken into account in the context of antibiotic susceptivity; research into antimicrobial mechanism. However there are few reports concerned with this study. Further research using different kinds of antibiotics with synchronized continuous culture of different bacterial strains is required.展开更多
In this study, the rubber tree clone PR107 was selected as test material,and its yields and physiological features under micro-tapping with different concentrations of ethylene were compared. The results showed that t...In this study, the rubber tree clone PR107 was selected as test material,and its yields and physiological features under micro-tapping with different concentrations of ethylene were compared. The results showed that there was no significant correlation between rubber yield and ethylene concentration applied by microtapping on PR107. Too high level of ethylene was not conducive to improvement of rubber yield. When the ethylene concentration for micro-tapping was higher than60%, physical deficiencies appeared in rubber tree PR107, the dry rubber content was reduced, and the yield was unstable. Instead, when the ethylene concentration was lower than 40%, the physiological features of PR107 were steady, the dry rubber content was stable, and the yield was relatively high.展开更多
基金Supported by the Natural Science Foundation of Shandong Province, China (Grant No. Y2005C58)the Natural Key Technology R&D Program of China (Grant No. 2006BAK02A03-6)the Youth Scientific Research Foundation of Shandong Academy of Agricultural Science (2005YQ035)
文摘According to the instantaneous growth rate (dN/dt) of E. coli CVCC249 growing in batch culture, the entire growth progress was distinguished into four phases: accelerating growth phase, constant growth phase, decelerating growth phase; declining phase, in each of which obvious variation in physiological; biochemical properties was detected, including total DNA, total protein,; MTT-dehydrogenase activity, etc., that led to difference in their antibiotic susceptivity. Antibiotic susceptivity of the population sampled from each phase was tested by Concentration-killing Curve (CKC) approach following the formula N=N 0/{1+exp[r·(x-BC 50)]}, showing as normal distribution at the individual cell level for an internal population, in which the median bactericidal concentration BC 50 represents the mean level of susceptivity, while the bactericidal span BC 199=(2lnN 0)/r indicates the variation degree of the antibiotic susceptivity. Furthermore, tested by CKC approach, the antibiotic susceptivity of E. coli CVCC249 population in each physiological phase to gentamicin or enoxacin was various: susceptivity of the population in the constant growth phase; declining phase all increased compared with that in the accelerating growth phase for gentamicin but declined for enoxacin. The primary investigations revealed that the physiological phase should be taken into account in the context of antibiotic susceptivity; research into antimicrobial mechanism. However there are few reports concerned with this study. Further research using different kinds of antibiotics with synchronized continuous culture of different bacterial strains is required.
基金Supported by Project of National Natural Rubber Industry Technology System of China(CARS-34-GW7)Project of Agricultural Technology Extension and System Construction for Tropical Crops(13RZNJ-43)Fundamental Research Funds of Rubber Research Institute,Chinese Academy of Tropical Agricultural Sciences(1630022013023)~~
文摘In this study, the rubber tree clone PR107 was selected as test material,and its yields and physiological features under micro-tapping with different concentrations of ethylene were compared. The results showed that there was no significant correlation between rubber yield and ethylene concentration applied by microtapping on PR107. Too high level of ethylene was not conducive to improvement of rubber yield. When the ethylene concentration for micro-tapping was higher than60%, physical deficiencies appeared in rubber tree PR107, the dry rubber content was reduced, and the yield was unstable. Instead, when the ethylene concentration was lower than 40%, the physiological features of PR107 were steady, the dry rubber content was stable, and the yield was relatively high.
文摘采用不同质量分数的聚乙二醇6000(Polyethylene glycol 6000,PEG6000)溶液模拟水分胁迫,研究4种白菜型冬油菜幼苗形态特征及生理生化特性,评判不同品种的抗旱性强弱。结果表明,PEG对4种白菜型冬油菜的成苗率、主根长、苗高、单株鲜质量、相对活力指数有显著的抑制效应;PEG质量分数为5%~15%时,超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性与胁迫质量分数呈正相关关系,在质量分数15%~20%时酶活性出现峰值,达显著性水平(P<0.05),随之下降。可溶性糖(SS)含量、可溶性蛋白(SPr)含量、脯氨酸(Proline)含量、相对电导率、丙二醛(MDA)含量与胁迫质量分数呈显著正相关关系。线性回归分析得到白菜型冬油菜PEG胁迫的半致死质量分数(LC50)为18.2%、半致死相对电导率(EC of LC50)为15.73%。4个品种的抗旱性顺序依次为:陇油6号>陇油7号>天油7号≥天油5号。
