Simultaneous recovery of dual pathways for ammonia metabolism do not improve further detoxification of ammonia in HepG2 cells

BACKGROUND:Key enzyme deficiency in the dual-pathway of ammonia metabolism leads to low detoxification capacity of HepG2 cells.Previously,we established a HepG2/AFhGS cell line with overexpression of human glutamine synthetase(hGS) in pathway 1 and a HepG2/(hArgI+hOTC)4 cell line with overexpression of human arginase I(hArgI) and human ornithine transcarbamylase(hOTC) in pathway 2.The present study aimed to investigate whether simultaneous recovery of the two pathways contributes to the further improvement of ammonia detoxification in HepG2 cells.METHODS:We adopted a recombinant retrovirus carrying the hGS gene to infect HepG2/(hArgI+hOTC)4 cells and selected a new recombinant HepG2 cell line.The capacities of ammonia tolerance and detoxification in cells were detected by biochemical methods.Cell cycle PCR chip was used to assess the changes of gene expression.RESULTS:Introducing hGS into HepG2/(hArgI+hOTC)4 cells did not lead to hGS overexpression,but inhibited hArgI expression.The levels of synthetic glutamine and urea in HepG2/(hArgI+hOTC+AFhGS)1 cells were significantly lower than those in HepG2/(hArgI+hOTC)4 cells when cultured in the medium with 10 and 15 mmol/L glutamate(Glu) and with 60 and 180 mmol/L NH 4 Cl,respectively.In addition,the comparison of different cell growth showed that HepG2/AFhGS cells significantly lagged behind the other cells by the 5th and 7th day,indicating that introduction of hGS impedes HepG2 cell proliferation.Analysis of the mechanism suggested that the decreased expression of BCL2 played an important role.CONCLUSIONS:This study demonstrated that the recovery of two ammonia metabolic pathways in HepG2 cells is not helpful in increasing ammonia metabolism.The reinforcement of the pathway of urea metabolism is more important and valuable in improving the ammonia metabolism capacity in HepG2 cells.

The Research Development of Respiratory Metabolism for Living Beings of Fishery Resources

[Objective]To describe the research development of respiratory metabolism for living beings of fishery resources home and abroad so as to provide reference for fishery production and management. [Method]Investigate research methods of respiratory metabolism about fish,shrimp, crab,shells and other living beings and analyze factors affecting their oxygen consumption rates and ammonia excretion rates according to research results of respiratory metabolism for living beings of fishery resources home and abroad. [Result] Respiratory metabolism is one of the important contents of bioenergetics research,an important part of energy balance research. It reflects not only the physiological status of living beings,but al- so the influence of environment condition on their physiological activities. Factors affecting respiratory metabolism are divided into biological factors and non-biological factors. By researching factors such as weight,temperature,activities,circadian rhythm,ingestion,Oxygen partial pressure and so on,we can evaluate respiratory metabolism of living beings of fishery resources. [Conclusion]Investigating from the individual physiology and e- cology to group physiology and ecology,the research provides data support for enhancement and releasing of sea ranch.