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Báo cáo khoa học: Stage specific expression of poly(malic acid)-affiliated genes in the life cycle of Physarum polycephalum Spherulin 3b and polymalatase

Polymalic acid is receiving interest as a unique biopolymer of the plasmodia of mycetozoa and recently as a biogenic matrix for the synthesis of devices for drug delivery. The acellular slime moldPhysarum polycephalumis charac-terized by two distinctive growth phases: uninucleated amoebae and multi-nucleated plasmodia. | iFEBS Journal Stage specific expression of poly malic acid -affiliated genes in the life cycle of Physarum polycephalum Spherulin 3b and polymalatase Nadthanan Pinchai Bong-Seop Lee and Eggehard Holler Institut fur Biophysik und Physikalische Biochemie der Universitat Regensburg Germany Keywords Physarum polycephalum plasmodium polymalatase polymalic acid spherulin 3b Correspondence E. Holler Institut fur Biophysik und Physikalische Biochemie der Universitat Regensburg D-93040 Regensburg Germany Fax 49 941 943 2813 Tel 49 941 943 3030 E-mail Eggehard.Holler@biologie. uni-regensburg.de Received 4 November 2005 revised 4 January 2006 accepted 9 January 2006 doi 10.1111 j.1742-4658.2006.05131.x Polymalic acid is receiving interest as a unique biopolymer of the plasmodia of mycetozoa and recently as a biogenic matrix for the synthesis of devices for drug delivery. The acellular slime mold Physarum polycephalum is characterized by two distinctive growth phases uninucleated amoebae and multinucleated plasmodia. In adverse conditions plasmodia reversibly transform into spherules. Only plasmodia synthesize poly malic acid PMLA and PMLA-hydrolase polymalatase . We have performed suppression subtractive hybridization SSH of cDNA from amoebae and plasmodia to identify plasmodium-specific genes involved in PMLA metabolism. We found cDNA encoding a plasmodium-specific spherulin 3a-like polypeptide NKA48 spherulin 3b but no evidence for a PMLA-synthetase encoding transcript. Inhibitory RNA RNAi -induced knockdown of NKA48-cDNA generated a severe reduction in the level of PMLA suggesting that spherulin 3b functioned in regulating the level of PMLA. Unexpectedly cDNA of poly-malatase was not SSH-selected suggesting its presence also in amoebae. Quantitative PCR then revealed low levels of mRNA in amoebae high levels in plasmodia and also low levels in spherules in agreement with the expression under transcriptional regulation in these cells. Physarum polycephalum is a versatile .