Construction of T7 RNA polymerase gene expression system in Anabaena sp. PCC 7120 for the expression of hG-CSF / 生物工程学报

The low expression rate of exogenous genes in cyanobacteria is one of the bottlenecks of cyanobacteria genetic engineering. The T7 RNA polymerase expression system has achieved the efficient expression of exogenous genes in Escherichia coli. Cyanobacteria and E. coli are both Gram-negative bacteria with high genetic homology. The construction of T7 RNA polymerase expression system in cyanobacteria may improve the expression of foreign genes. In order to construct the T7 RNA polymerase expression system in Anabaena sp. PCC 7120, methods such as overlapping extension PCR and digestion-ligation technique were used to construct a site-specific integration vector pEASY-T1-F1-TacT7RNAPCmR-F2 and a shuttle expression vector pRL-T7-hG-CSF. The site-specific integration vector is capable of expressing T7 RNA polymerase, and the shuttle expression vector expresses hG-CSF driven by the T7 promoter. Then we introduced the site-specific integration vector into the wild type cyanobacteria by electroporation and transferred the shuttle expression vector into the site-integrated transgenic cyanobacteria by triparental conjugative transfer. In the end, we identified the presence of foreign genes in cyanobacteria by PCR, tested the transcription level of foreign genes in cyanobacteria by RT-PCR, and detected the protein expression of foreign genes in cyanobacteria by Western blotting. The two vectors were successfully constructed, the T7 RNA polymerase gene and hG-CSF gene were transferred into cyanobacteria well, and both genes were also expressed in cyanobacteria. In summary, the T7 RNA polymerase expression system was successfully constructed in cyanobacteria, and the expression rate of hG-CSF gene was doubled than the traditional cyanobacteria expression systems. This expression system will provide a better tool for the application of cyanobacteria genetic engineering and will promote the development of cyanobacteria as a chassis cell in the fields of synthetic biology in the future.

DNA barcoding of rodent in Ningxia Hui Autonomous Region,China / 中国人兽共患病学报

ABSTRACT:To improve the ability of correct classification and identification of rodents in different kinds of foci of zoonosis in Ningxia Hui Autonomous Region in China ,rodents samples from different habitats of Ningxia were collected .Sequences of COI gene were amplified and sequenced from 154 samples .Based on these sequences ,the pairwise genetic distance were calcu‐lated ,and a Neighbor Joining tree were constructed .According to the NJ tree ,20 clusters with high bootstrap support were found from 19 morphological species .The striped dwarf hamsters were divided into two clusters ,which suggested that there were two cryptic species with stripe on the back .The pika from Helan Mountain showed close relationship with Ochotona pal‐lasi ,and the genetic distance was as low as 3 .6% .Results show that DNA barcodes could be used to accurately identify speci‐mens of rodents and correct morphological identification errors .It could discover appearance indistinguishable implied species and could better study the classification and evolution of rodents .