Study On The Translational Regulation Of RNases In Anabaena PCC 7120

Ribonucleases(RNases)are responsible for post-transcriptional regulation,playing important roles in the RNA’s processing,mature and degradation.They do not simply act as "killers" to degrade RNAs;they also help cells adapt to external environment by recycling ribonucleotide,supervising and eliminating redundant or harmful RNA.Anabaena sp.PCC7120 is a kind of filamentous cyanobacterium.When facing nitrogen deficiency,a portion of its cells are able to develop into heterocysts for nitrogen fixation.During this process,cellular activities and gene expression change dramatically.Ribonucleases are key enzymes required for cellular growth.However,how their expression is regulated in adaptation to nitrogen-starvation environment and in heterocyst differentiation remains unknown.In this study,using Western-blotting we quantified the protein levels of all known ribonucleases in the filaments of Anabaena sp.PCC7120,and checked their change when cells were subjected to nitrogen-starvation condition.It was shown that ribonucleases differ to each other significantly in term of their cellular content under normal growth condition.Upon nitrogen deficiency,the expression level of most exoribonuleases inceased at first and soon dropped to the original level;most endonucleases could not be detected except that RNase E was constantly expressed.We are going to examine the expression of ribonucleases in isolated heterocysts.This study would provide us with an overview of how cellar ribonucleases are regulated to at translational level,and with better understanding about the importance of these ribonucleases in cellular growth and differentiation.