Bacterial Transcription Factors in Gene Expression Regulation / 中国生物化学与分子生物学报

Transcription factors (TFs) are key proteins that regulate gene expression by guiding RNA polymerases to bind to specific DNA sequences in cells, thus enabling organisms to respond to environmental changes rapidly and achieving better survival adaptability. Most bacterial transcription factors are composed of two parts: a DNA-binding domain and a regulatory domain, but some transcription factors have only one DNA-binding domain. According to the functional profile, they can be classified as activating transcription factors and repressive transcription factors. The important function of bacterial transcription factors is to sense changes in environmental conditions and to adjust the expression of related genes accordingly, at same time they are also affected by other signaling molecules. They often form a complex regulatory network with each other and jointly manage the expression of genes to cope with the environmental signals. Due to the importance of bacterial transcription factors in gene regulation, it has become a hot spot in molecular biology research. In this review, we summarize the study of bacterial transcription factors in recent years, focusing on their structures and function mechanisms and roles in stress response, in order to provide ideas for a systematic understanding of the topic.

[Dynamic simulation analysis of effects of project of ditching for drain on Oncomelania hupensis snail control and flood prevention security in Dongting Lake region].

OBJECTIVE: To evaluate the effects of the project of ditching for drain on Oncomelania hupensis snail control and flood prevention security and explore the optimal engineering design plan in Dongting Lake region. METHODS: A retrospective study was performed on the previous studies about the project of ditching for drain. The reference values of project indices were determined. The outside levee of Nanhu New Distinct of Yueyang City in Dongting Lake region was selected as the study area, and the cross section of marshland perpendicular to the center line of the levee was extracted to research. According to the situations of various water levels, a dynamic simulation was performed on the effect and security of the project of ditching for drain through the software FLAC3D. RESULTS: The retrospective study showed that the project would be effective when the relatively subsoil water level decreased by 0.35 m, and the soil water content decreased correspondingly. The dynamic simulation by FLAC3D showed that the minimum safe distances between transverse ditch 1, vertical ditch and levee toe should be 25 m and 13 m respectively. The digging depth of transverse ditch and vertical ditch should be 1.2 m and 1.0 m respectively. If the width of marshland in drought period was less than 500 m, one transverse ditch was efficient. Otherwise, more transverse ditches should be set with the intervals of 300 m. CONCLUSIONS: The project of ditching for drain is an effective ecological snail elimination method. Optimizing the digging depth of ditches and distances between transverse ditches, vertical ditch and levee toe will ensure the effects and security of the project.