This study investigate the effect of the concentration of nitrate and phosphate, present in the culture medium, on the chemical and biochemical composition of the products from the marine microalgae, Nannochloropsis s...This study investigate the effect of the concentration of nitrate and phosphate, present in the culture medium, on the chemical and biochemical composition of the products from the marine microalgae, Nannochloropsis sp.. Experimental design allowed the assessment, in a systematic way, of the response of the microalgae to the nitrate and phosphate concentrations, and the way they lead to changes in the total amount of carotenoids, chlorophyll a, iron and magnesium produced or uptaken. The total carotenoids presented a higher yield when cultivated under lower phosphate concentrations, but showed no change with nitrate concentration. Chlorophyll a yield increased in the presence of higher concentrations of nitrogen and lower concentrations of phosphorus. There was an increase in the amount of iron absorbed by cells when higher levels of nitrates were present, but the effect is insignificant with phosphates. The magnesium content was not significantly affected by culture manipulation. The results also showed that the biomass yield of the microalgae Nannochloropsis sp. was negatively affected by the N/P ratio. The antioxidative potential of the microalgae, in contrast, was found to increase with the N/P ratio.展开更多
Background Endoplasmic reticulum （ER） stress-related apoptosis is involved in the pathophysiology of many cardiovascular diseases, and Panax quinquefolium saponin （PQS） is able to inhibit excessive ER stress-relat...Background Endoplasmic reticulum （ER） stress-related apoptosis is involved in the pathophysiology of many cardiovascular diseases, and Panax quinquefolium saponin （PQS） is able to inhibit excessive ER stress-related apoptosis of cardiomyocytes following hypoxia/reoxygenation and myocardial infarction. However, the pathway by which PQS inhibits the ER stress-related apoptosis is not well understood. To further investigate the protective effect of PQS against ER stress-related apoptosis, primary cultured eardiomyocytes were stimulated with thapsigargin （TG）, which is widely used to model cellular ER stress, and it could induce apoptotic cell death in sufficient concentration. Methods Primary cultured cardiomyocytes from neonatal rats were exposed to TG （1 μmol/L） treatment for 24 h, following PQS pre-treatment （160 μg/mL） for 24 h or pre-treatment with small interfering RNA directed against protein kinase-like endoplasmic reticulum kinase （Si-PERK） for 6 h. The viability and apoptosis rate of cardiomyocytes were detected by cell counting kit-8 and flow cytometry respectively. ER stress-related protein expression, such as glucose-regulated protein 78 （GRP78）, calreticulin, PERK, eukaryotic translation initiation factor 2α （elF2c0, activating transcription factor 4 （ATF4）, and C/EBP homologous protein （CHOP） were assayed by western blotting. Results Both PQS pre-treatment and PERK knockdown remarkably inhibited the cardiomyocyte apoptosis induced by TG, increased cell viability, decreased phosphorylation of both PERK and eIF2α, and decreased protein levels of both ATF4 and CHOP. There was no statistically significant difference between PQS pre-treatment and PERK knockdown in the cardioprotective effect. Conclusions Our data indicate that the PERK-eIF2α-ATF4-CHOP pathway of ER stress is involved in the apoptosis induced by TG, and PQS might prevent TG-induced cardiomyocyte apoptosis through a mechanism involving the suppression of this pathway. These findings provide novel data regarding the molecular mechanisms by which PQS inhibits cardiomyocyte apoptosis.展开更多
文摘This study investigate the effect of the concentration of nitrate and phosphate, present in the culture medium, on the chemical and biochemical composition of the products from the marine microalgae, Nannochloropsis sp.. Experimental design allowed the assessment, in a systematic way, of the response of the microalgae to the nitrate and phosphate concentrations, and the way they lead to changes in the total amount of carotenoids, chlorophyll a, iron and magnesium produced or uptaken. The total carotenoids presented a higher yield when cultivated under lower phosphate concentrations, but showed no change with nitrate concentration. Chlorophyll a yield increased in the presence of higher concentrations of nitrogen and lower concentrations of phosphorus. There was an increase in the amount of iron absorbed by cells when higher levels of nitrates were present, but the effect is insignificant with phosphates. The magnesium content was not significantly affected by culture manipulation. The results also showed that the biomass yield of the microalgae Nannochloropsis sp. was negatively affected by the N/P ratio. The antioxidative potential of the microalgae, in contrast, was found to increase with the N/P ratio.
基金Acknowledgements This work was supported by International Science and Technology Cooperation Project （2010DFA31690）, National Natural Science Foundation of China （81030063 and 81170140） and China Postdoctoral Science Foundation （2014M562608）. The authors declare no conflict of interests regarding the publication of this paper.
文摘Background Endoplasmic reticulum （ER） stress-related apoptosis is involved in the pathophysiology of many cardiovascular diseases, and Panax quinquefolium saponin （PQS） is able to inhibit excessive ER stress-related apoptosis of cardiomyocytes following hypoxia/reoxygenation and myocardial infarction. However, the pathway by which PQS inhibits the ER stress-related apoptosis is not well understood. To further investigate the protective effect of PQS against ER stress-related apoptosis, primary cultured eardiomyocytes were stimulated with thapsigargin （TG）, which is widely used to model cellular ER stress, and it could induce apoptotic cell death in sufficient concentration. Methods Primary cultured cardiomyocytes from neonatal rats were exposed to TG （1 μmol/L） treatment for 24 h, following PQS pre-treatment （160 μg/mL） for 24 h or pre-treatment with small interfering RNA directed against protein kinase-like endoplasmic reticulum kinase （Si-PERK） for 6 h. The viability and apoptosis rate of cardiomyocytes were detected by cell counting kit-8 and flow cytometry respectively. ER stress-related protein expression, such as glucose-regulated protein 78 （GRP78）, calreticulin, PERK, eukaryotic translation initiation factor 2α （elF2c0, activating transcription factor 4 （ATF4）, and C/EBP homologous protein （CHOP） were assayed by western blotting. Results Both PQS pre-treatment and PERK knockdown remarkably inhibited the cardiomyocyte apoptosis induced by TG, increased cell viability, decreased phosphorylation of both PERK and eIF2α, and decreased protein levels of both ATF4 and CHOP. There was no statistically significant difference between PQS pre-treatment and PERK knockdown in the cardioprotective effect. Conclusions Our data indicate that the PERK-eIF2α-ATF4-CHOP pathway of ER stress is involved in the apoptosis induced by TG, and PQS might prevent TG-induced cardiomyocyte apoptosis through a mechanism involving the suppression of this pathway. These findings provide novel data regarding the molecular mechanisms by which PQS inhibits cardiomyocyte apoptosis.
