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Microcystis aeruginosa is the main cyanobacteria,which can form "water bloom" in lakes and reservoirs.So use the technologies of molecular biology and proteomics to study valued differential proteins expressed under specific conditions,which will either in theory or in practice pour great effect on the prevention of algae bloom.In the formation of algae bloom,the proportion of nitrogen and phosphorus is a major factor.The optimal N/P for alage is 16:1.So it is assumed that the particular proporation must relate to the growth and division of cyanobacteria cells.Other than participated in the phosphorylate reaction in metabolic pathways,the most vital role in vivo of phosphorus is involved in DNA、RNA synthesis.As for nitrogen,it is related to the protein synthesis.The appropriate ratio between N and P may be presumed as a reflection of the relation in quantity between the growth and division of alage cell.In order to verify the assumption,we use the technology of FCM to detect the cells of M.aeruginosa stained by PI,which were cultured on different N/P nutrients.Acoording to other papers,it sets different N/P ratios,as 16:1,160:1,1:1 and lacking of NP four groups.The results show that,when N/P=16:l,the DNA content of M.aeruginosa cells is higher than others.So it comes to a conclusion that the division of these cells is at an optimal level.The phosphorus is a vital limiting factor for the growth of cyanobacteria,which also play a role in the breakout of algae bloom.In fact,M.aeruginosa has a maximum uptake rate of phosphorus.With a greater storage capacity of phosphorus than other cyanobacterias,M.aeruginosa can store adequate phosphorus in vivo.So it arose us great interest to study the metabolic mechanism of phosphorus in M.aeruginosa.The analysis of proteins expression level for M.aeruginosa induced at different phosphorus concentrations will help to unfold the metabolic mechanism of phosphorus.In the experiment,we set three different phosphorus concentrations: 0.005mg/L,0.05mg/L,0.5mg/L.After cultured on the three different nutrients for 72h, the cells were collected for differential proteomic study.Two-dimensional electrophoresis results show more than 20 differential protein spots,from which 11 differential proteins were chosen for MALDI-TOF analysis.(PGK),Then though data retrieval some important proteins related to phosphorus metabolism have been obtained,they are:thiamine-phosphate pyrophosphorylase(TPP),thioredoxin peroxidase,microcystin related protein MrpA,succinyl-CoA synthetase,ABC transporter related protein,succinyl-CoA synthetase beta chain,phosphoglycerate kinase,Bacterial fructose-1,6-bisphosphatase(glpx),Ycf48-like protein precursor, and so on.Then do study primarily on the function of protein PstB.The western blot detection of the expression of PstB in M.aeruginosa under different phosphorus concentrations reveals that,the gene coding for PstB,is induced under lacking for phosphorus condition.So when phosphorus concentration in vitro in low,the gene pstB can ensure M.aeruginosa absorp external phosphorus in maximum.It is concluded that PstB plays an important role in the absorption and transportation of phosphorus.
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