The Changes Of Photosynthesis Pigments And Proteins Expression In The Cyanobacterium Anabaena Sp. PCC7120 Under Desiccation

The N₂-fixing cyanobacterium Anabaena sp.PCC7120 showed an inherent capacity for desiccation tolerance.They suffered some physiological changes especially the degradation of photosynthesis pigments,under desiccation.In this study,the changes of chlorophyll and phycocyanin in the cyanobactrium were examined.And then,the degradation of chlorophyll was determined as an indicator for desiccation.A 2-dimensional gel electrophoresis was carried out to compare the protein expression between desiccated samples and indesiccated samples.1.The indicator for desiccation stress in this study and the alteration of the photosynthetic pigments under desiccation stress.The preferred desiccation stress was as follows:collection of filaments were absorbed on filter-paper and air-dried on continuous illumination(3.5J^*m^-2*s^-1),28℃, relative humidity 30%.In order to determine an appropriate desiccation stress,the variation of chlorophyll and phycocyanin contents were examined..Owing to the convenience of detecting chlorophyll content and no effects of sulfur or nitrogen limitation,along with the extension of desiccate time as well,it had been determined as desiccation criterion,thus an evaluation system was built.2.The protein expression profile analysis of Anabaena PCC 7120 under desiccation stress by 2-D electrophoresisThe soluble proteins extracted from cells under different condition were seperated by polyacrylam two-dimensional gel electrophoresis and the profile differences was characterized by comparing the variation of protein spots in different condition.3.The prediction of desiccation-related genes in Anabaena PCC 7120 by informaticsInformatics analysis showed that a number of genes related to desiccation-stress response in Anabaena PCC 7120,including:1) possible up-regulated genes,they are genes associated with glycolysis,remove of oxidative free radical,transcriptional factors regulating desiccation-tolerant relative genes,chaperones and heat-shocking proteins;2) possible down-regulated genes,they are genes involved in carbon dioxide absorption, photosynthesis,transport of nitrogen and carbohydrate,transcription and translation, synthesis of membrane lipid and polysaccharide,desaturase and dehydration.