A virtual reconfigurable architecture(VRA)-based evolvable hardware is proposed for automatic synthesis of combinational logic circuits at gate-level.The proposed VRA is implemented by a Celoxica RC1000 peripheral com...A virtual reconfigurable architecture(VRA)-based evolvable hardware is proposed for automatic synthesis of combinational logic circuits at gate-level.The proposed VRA is implemented by a Celoxica RC1000 peripheral component interconnect(PCI)board with an Xilinx Virtex xcv2000E field programmable gate array(FPGA).To improve the quality of the evolved circuits,the VRA works through a two-stage evolution: finding a functional circuit and minimizing the number of logic gates used in a feasible circuit.To optimize the algorithm performance in the two-stage evolutionary process and set free the user from the time-consuming process of mutation parameter tuning,a self-adaptive mutation rate control(SAMRC)scheme is introduced.In the evolutionary process,the mutation rate control parameters are encoded as additional genes in the chromosome and also undergo evolutionary operations.The efficiency of the proposed methodology is tested with the evolutions of a 4-bit even parity function,a 2-bit multiplier,and a 3-bit multiplier.The obtained results demonstrate that our scheme improves the evolutionary design of combinational logic circuits in terms of quality of the evolved circuit as well as the computational effort,when compared to the existing evolvable hardware approaches.展开更多
Development of controllable hypermutable cells can greatly benefit understanding and harnessing microbial evolution.However,there have not been any similar sys-tems developed for Clostridium,an important bacterial gen...Development of controllable hypermutable cells can greatly benefit understanding and harnessing microbial evolution.However,there have not been any similar sys-tems developed for Clostridium,an important bacterial genus.Here we report a novel two-step strategy for de-veloping controllable hypermutable cells of Clostridium acetobutylicum,an important and representative indus-trial strain.Firstly,the mutS/L operon essential for methyl-directed mismatch repair(MMR)activity was inactivated from the genome of C.acetobutylicum to generate hy-permutable cells with over 250-fold increased mutation rates.Secondly,a proofreading control system carrying an inducibly expressed mutS/L operon was constructed.The hypermutable cells and the proofreading control system were integrated to form a controllable hypermut-able system SMBMutC,of which the mutation rates can be regulated by the concentration of anhydrotetracycline(aTc).Duplication of the miniPthl-tetR module of the proof-reading control system further signifi cantly expanded the regulatory space of the mutation rates,demonstrating hypermutable Clostridium cells with controllable mutation rates are generated.The developed C.acetobutylicum strain SMBMutC2 showed higher survival capacities than the control strain facing butanol-stress,indicating greatly increased evolvability and adaptability of the controllable hypermutable cells under environmental challenges.展开更多
基金Projects(61203308,61309014)supported by the National Natural Science Foundation of China
文摘A virtual reconfigurable architecture(VRA)-based evolvable hardware is proposed for automatic synthesis of combinational logic circuits at gate-level.The proposed VRA is implemented by a Celoxica RC1000 peripheral component interconnect(PCI)board with an Xilinx Virtex xcv2000E field programmable gate array(FPGA).To improve the quality of the evolved circuits,the VRA works through a two-stage evolution: finding a functional circuit and minimizing the number of logic gates used in a feasible circuit.To optimize the algorithm performance in the two-stage evolutionary process and set free the user from the time-consuming process of mutation parameter tuning,a self-adaptive mutation rate control(SAMRC)scheme is introduced.In the evolutionary process,the mutation rate control parameters are encoded as additional genes in the chromosome and also undergo evolutionary operations.The efficiency of the proposed methodology is tested with the evolutions of a 4-bit even parity function,a 2-bit multiplier,and a 3-bit multiplier.The obtained results demonstrate that our scheme improves the evolutionary design of combinational logic circuits in terms of quality of the evolved circuit as well as the computational effort,when compared to the existing evolvable hardware approaches.
基金the National Natural Science Foundation of China(Grant No.31270107)the National Basic Research Program of China(973 Program)(No.2011CBA00800)+1 种基金the National High Technology Research and Development Program(863 Program)(No.2011AA02A208)the Knowledge Innovation Program of the Chinese Acad-emy of Sciences(No.KSCX2-EW-Q-14).
文摘Development of controllable hypermutable cells can greatly benefit understanding and harnessing microbial evolution.However,there have not been any similar sys-tems developed for Clostridium,an important bacterial genus.Here we report a novel two-step strategy for de-veloping controllable hypermutable cells of Clostridium acetobutylicum,an important and representative indus-trial strain.Firstly,the mutS/L operon essential for methyl-directed mismatch repair(MMR)activity was inactivated from the genome of C.acetobutylicum to generate hy-permutable cells with over 250-fold increased mutation rates.Secondly,a proofreading control system carrying an inducibly expressed mutS/L operon was constructed.The hypermutable cells and the proofreading control system were integrated to form a controllable hypermut-able system SMBMutC,of which the mutation rates can be regulated by the concentration of anhydrotetracycline(aTc).Duplication of the miniPthl-tetR module of the proof-reading control system further signifi cantly expanded the regulatory space of the mutation rates,demonstrating hypermutable Clostridium cells with controllable mutation rates are generated.The developed C.acetobutylicum strain SMBMutC2 showed higher survival capacities than the control strain facing butanol-stress,indicating greatly increased evolvability and adaptability of the controllable hypermutable cells under environmental challenges.
