The substrate-dependent regulatory effects of the AfeI/R system in Acidithiobacillus ferrooxidans reveals the novel regulation strategy of quorum sensing in acidophiles.

A LuxI/R-like quorum sensing (QS) system (AfeI/R) has been reported in the acidophilic and chemoautotrophic Acidithiobacillus spp. However, the function of AfeI/R remains unclear because of the difficulties in the genetic manipulation of these bacteria. Here, we constructed different afeI mutants of the sulfur- and iron-oxidizer A. ferrooxidans, identified the N-acyl homoserine lactones (acyl-HSLs) synthesized by AfeI, and determined the regulatory effects of AfeI/R on genes expression, extracellular polymeric substance synthesis, energy metabolism, cell growth and population density of A. ferrooxidans in different energy substrates. Acyl-HSLs-mediated distinct regulation strategies were employed to influence bacterial metabolism and cell growth of A. ferrooxidans cultivated in either sulfur or ferrous iron. Based on these findings, an energy-substrate-dependent regulation mode of AfeI/R in A. ferrooxidans was illuminated that AfeI/R could produce different types of acyl-HSLs and employ specific acyl-HSLs to regulate specific genes in response to different energy substrates. The discovery of the AfeI/R-mediated substrate-dependent regulatory mode expands our knowledge on the function of QS system in the chemoautotrophic sulfur- and ferrous iron-oxidizing bacteria, and provides new insights in understanding energy metabolism modulation, population control, bacteria-driven bioleaching process, and the coevolution between the acidophiles and their acidic habitats.

[Clinical studies on different coronary artery interventional therapies through femoral artery or radial artery approaches].

OBJECTIVE: To compare the clinical efficacies regarding femoral artery or radial artery approaches on coronary artery interventional therapies. METHODS: 360 patients were randomly divided into intervention group via femoral artery (TFI) or transradial coronary intervention (TRI) group. Postoperative observation on the two said groups of patients with vascular lesion characteristics, feasibility factors (success rate of interventional therapy puncture, time of operation and hospitalization) and complications, were made. RESULTS: There were no significant differences between the two groups on the characteristics of vascular lesion (P>0.05). Success rates of the two groups were 97.78% and 96.67% respectively. The differences on success rate, time of operation were not statistically significant (P>0.05) while the average time of puncture, the mean duration of hospitalization and the rates of complications were significantly different (P<0.05). CONCLUSION: The two methods under comparison had similar success rate and feasibility. However, the complications related to radial artery interventional therapy were much less than the femoral artery interventional therapy. As having better safety, radial artery interventional therapy seemed to have applicable value on clinical practice.