An minimum description length(MDL) criterion is proposed to choose a good partition for a bipartite network. A heuristic algorithm based on combination theory is presented to approach the optimal partition. As the heuristic algorithm automatically searches for the number of partitions, no user intervention is required. Finally, experiments are conducted on various datasets, and the results show that our method generates higher quality results than the state-of-art methods, cross-association and bipartite, recursively induced modules. Experiment results also show the good scalability of the proposed algorithm. The method is applied to traditional Chinese medicine(TCM) formula and Chinese herbal network whose community structure is not well known, and found that it detects significant and it is informative community division.
[ Objective] To express lactate dehydrogenase C （LDH-C） gene in prokaryotic system and then purify the recombinant protein. E Meth- od] The LDI-I-C gene was amplified from black-lipped pika（ Ochotona curzoniae） by RT-PCR and ligated to the expression vector pET-32a. The E. coli BL21 （DE3） carrying the LDI-I-C gene was obtained and induced by IPTG （isopropy-beta-D-thiogalactoside）. The expression products were analyzed by SDS-PAGE and purified by affinity chromatography. L Result] An approximately 1.0 kbp band appeared in the RT-PCR products as the- oretically expected. As evidenced by PCR and double enzyme digestion, an approximately 1.0 kbp fragment appeared, which indicated successful construction of expression vector. As analyzed by SDS-PAGE, a fusion protein with molecular weight slightly larger than 45 kDa was expressed in form of inclusion body. And very pure fusion protein was obtained by nickel ions-charged affinity chromatography. [ Coaclusion] The LDH-C gene of black-lipped pika has been cloned and expressed in E. coil
