A model, for evaluating the effect of porosity and volume fraction of extracellular polymeric substances (EPS) within multispecies biofilms on the effective diffusivity, is developed and experimentally validated, base...A model, for evaluating the effect of porosity and volume fraction of extracellular polymeric substances (EPS) within multispecies biofilms on the effective diffusivity, is developed and experimentally validated, based on the extraction of EPS from intact biofilms. The amount of EPS in biofilms significantly affects the effective diffusivity. For biofilms with porosity of 77%—95% in the top layers and 54%—58% in the bottom layers, the value of De/Dw decreases from 0.52—0.83 in the top layers to 0.23—0.31 in the bottom layers. Generally, the effective diffusivity in the heterotrophic/autotrophic biofilms is slightly lower than that in the heterotrophic biofilms, due to the lower porosity in the heterotrophic/autotrophic biofilms.展开更多
AIM： To determine the prevalence of porcine endogenous retrovirus （PERV） in various pig breeds raised in China including Chinese experimental mini-pigs by PERV-reverse transcriptase （PERV-RT enzyme）. Moreover, th...AIM： To determine the prevalence of porcine endogenous retrovirus （PERV） in various pig breeds raised in China including Chinese experimental mini-pigs by PERV-reverse transcriptase （PERV-RT enzyme）. Moreover, the potential for infection of PERV was investigated in patients treated with a bioreactor based on porcine liver cells （n = 3）. METHODS： Pig serum, liver and muscle cell-free supernatants were collected from various Chinese pig breeds. Porcine hepatocytes were isolated with a two-step perfusion method. Three patients with acute or chronic liver failure were treated with a bioartificial liver support system （BALSS） for 8-12 h and serum samples were collected from the patients before, immediately after and 30 d after treatment. RESULTS： The activities of PERV-RT enzyme in pig liver and muscle cell-free supernatants were higher than in normal human controls. PERV-TR enzyme activity did not increase in patients before and after 1 mo of treatment. PERV-RT activities were not significantly different when compared with pre-treatment group （1.544±0.155576）, the post-treatment groups （1.501±0.053507, 1.461±0.033808 and 1.6006667±0.01963 for 0, 14 and 30 d post-treatment, respectively, P〉0.05）, and normal control group （1.440±1.0641, P〉0.05）. RT enzyme activity in Chinese experimental mini-pigs was higher than in normal human control group （1.440±1.0641 U/mL, P〈0.05）, and not significantly different （P〉0.05） when compared with the pig breeds except in the muscle supernatants. All the samples including muscle and liver cell supernatants from the Chinese mini-experimental pigs and the four domestic Chinese pig breeds contained PERVs. CONCLUSION： These results suggest that the risk of PERV infection through BALSS containing porcine liver cells without immunosuppressants may be quite low. Although there were PERVs in Chinese experimental mini-pigs and porcine liver cell culture suspensions, we did not find any evidence of persistent PERV infection in patients treated with this porcine hepatocyte-based bioartificial liver.展开更多
Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals.The typical heterocystous cyanoba...Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals.The typical heterocystous cyanobacterium Anabaena sp.PCC 7120 was grown in the presence of exogenous glucose in light.Glucose improved the cell growth evidently,the maximal specific growth rate under mixotrophic condition（0.38 d 1）being 1.6-fold of that of photoautotrophic growth.Mixotrophy caused a variation in cellular pigment composition,increasing the content of chlorophyll a and decreasing the contents of carotenoid and phycobiliprotein relative to chlorophyll a.Fluorescence emission from photosystem II（PSII）relative to photosystem I was enhanced in mixotrophic cells,implying an increased energy distribution in PSII.Glucokinase（EC 2.7.1.2）activity was further induced in the presence of glucose.The mixotrophic culture was scaled up in a 15 L airlift photobioreactor equipped with an inner and an outer light source.A modified Monod model incorporating the specific growth rate and the average light intensity in the reactor was developed to describe cell growth appropriately.The understanding of mixotrophic growth and relevant physiological features of Anabaena sp.PCC 7120 would be meaningful for cultivation and exploitation of this important cyanobacterial strain.展开更多
Ion-sensitive field-effect transistor （ISFET）-based biosensor for amino acids was proposed, and the response of the sensor to amino acids was evaluated. As a molecular recognition element, aminoacyl-tRNA synthetase ...Ion-sensitive field-effect transistor （ISFET）-based biosensor for amino acids was proposed, and the response of the sensor to amino acids was evaluated. As a molecular recognition element, aminoacyl-tRNA synthetase which would be expected to have high selectivity for the corresponding amino acids was used, aminoacyl-tRNA synthetase was coated onto an ISFET electrode, and the response of the biosensor to amino acids was evaluated. The amino acid sensor for tyrosine showed a selective response to tyrosine because of the specific binding ability of aminoacyl-tRNA synthetase for tyrosine and from 300μM to 900 μM of tyrosine could be measured （r2 〉 0.969）.展开更多
基金Supported by the National Natural Science Foundation of China (Project No. 29976030)863 Hi-Technology Research and Development Program of China (2004AA649340).
文摘A model, for evaluating the effect of porosity and volume fraction of extracellular polymeric substances (EPS) within multispecies biofilms on the effective diffusivity, is developed and experimentally validated, based on the extraction of EPS from intact biofilms. The amount of EPS in biofilms significantly affects the effective diffusivity. For biofilms with porosity of 77%—95% in the top layers and 54%—58% in the bottom layers, the value of De/Dw decreases from 0.52—0.83 in the top layers to 0.23—0.31 in the bottom layers. Generally, the effective diffusivity in the heterotrophic/autotrophic biofilms is slightly lower than that in the heterotrophic biofilms, due to the lower porosity in the heterotrophic/autotrophic biofilms.
文摘AIM： To determine the prevalence of porcine endogenous retrovirus （PERV） in various pig breeds raised in China including Chinese experimental mini-pigs by PERV-reverse transcriptase （PERV-RT enzyme）. Moreover, the potential for infection of PERV was investigated in patients treated with a bioreactor based on porcine liver cells （n = 3）. METHODS： Pig serum, liver and muscle cell-free supernatants were collected from various Chinese pig breeds. Porcine hepatocytes were isolated with a two-step perfusion method. Three patients with acute or chronic liver failure were treated with a bioartificial liver support system （BALSS） for 8-12 h and serum samples were collected from the patients before, immediately after and 30 d after treatment. RESULTS： The activities of PERV-RT enzyme in pig liver and muscle cell-free supernatants were higher than in normal human controls. PERV-TR enzyme activity did not increase in patients before and after 1 mo of treatment. PERV-RT activities were not significantly different when compared with pre-treatment group （1.544±0.155576）, the post-treatment groups （1.501±0.053507, 1.461±0.033808 and 1.6006667±0.01963 for 0, 14 and 30 d post-treatment, respectively, P〉0.05）, and normal control group （1.440±1.0641, P〉0.05）. RT enzyme activity in Chinese experimental mini-pigs was higher than in normal human control group （1.440±1.0641 U/mL, P〈0.05）, and not significantly different （P〉0.05） when compared with the pig breeds except in the muscle supernatants. All the samples including muscle and liver cell supernatants from the Chinese mini-experimental pigs and the four domestic Chinese pig breeds contained PERVs. CONCLUSION： These results suggest that the risk of PERV infection through BALSS containing porcine liver cells without immunosuppressants may be quite low. Although there were PERVs in Chinese experimental mini-pigs and porcine liver cell culture suspensions, we did not find any evidence of persistent PERV infection in patients treated with this porcine hepatocyte-based bioartificial liver.
基金Supported by a grant from the State Key Laboratory of Biochemical Engineering,Institute of Process Engineering,Chinese Academy of Sciences
文摘Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals.The typical heterocystous cyanobacterium Anabaena sp.PCC 7120 was grown in the presence of exogenous glucose in light.Glucose improved the cell growth evidently,the maximal specific growth rate under mixotrophic condition（0.38 d 1）being 1.6-fold of that of photoautotrophic growth.Mixotrophy caused a variation in cellular pigment composition,increasing the content of chlorophyll a and decreasing the contents of carotenoid and phycobiliprotein relative to chlorophyll a.Fluorescence emission from photosystem II（PSII）relative to photosystem I was enhanced in mixotrophic cells,implying an increased energy distribution in PSII.Glucokinase（EC 2.7.1.2）activity was further induced in the presence of glucose.The mixotrophic culture was scaled up in a 15 L airlift photobioreactor equipped with an inner and an outer light source.A modified Monod model incorporating the specific growth rate and the average light intensity in the reactor was developed to describe cell growth appropriately.The understanding of mixotrophic growth and relevant physiological features of Anabaena sp.PCC 7120 would be meaningful for cultivation and exploitation of this important cyanobacterial strain.
文摘Ion-sensitive field-effect transistor （ISFET）-based biosensor for amino acids was proposed, and the response of the sensor to amino acids was evaluated. As a molecular recognition element, aminoacyl-tRNA synthetase which would be expected to have high selectivity for the corresponding amino acids was used, aminoacyl-tRNA synthetase was coated onto an ISFET electrode, and the response of the biosensor to amino acids was evaluated. The amino acid sensor for tyrosine showed a selective response to tyrosine because of the specific binding ability of aminoacyl-tRNA synthetase for tyrosine and from 300μM to 900 μM of tyrosine could be measured （r2 〉 0.969）.
