Vibrio vulnificus Cytolysin Forms Anion-selective Pores on the CPAE Cells, a Pulmonary Endothelial Cell Line

Cytolysin produced by Vibrio vulnificus has been incriminated as one of the important virulence determinants in V. vulnificus infection. Ion selectivity of cytolysin-induced pores was examined in a CPAE cell, a cell line of pulmonary endothelial cell, using inside-out patch clamp techniques. In symmetrical NaCl concentration (140 mM), intracellular or extracellular application of cytolysin formed ion-permeable pores with a single channel conductance of 37.5 4.0 pS. The pore currents were consistently maintained after washout of cytolysin. Replacement of Na in bath solution with monovalent ions (K, Cs or TEA ) or with divalent ions (Mg2, Ca2 ) did not affect the pore currents. When the NaCl concentration in bath solution was lowered from 140 to 60 and 20 mM, the reversal potential shifted from 0 to 11.8 and 28.2 mV, respectively. The relative permeability of the cytolysin pores to anions measured at 40 mV was Cl = NO2 > or = Br = I > SCN > acetate > isethionate > ascorbic acid > EDTA2, in descending order. The cytolysin-induced pore current was blocked by Cl channel blockers or nucleotides. These results indicate that V. vulnificus cytolysin forms anion-selective pores in CPAE cells.

Study on the Growth for Selectivity to Negative Ion of Moderately Halophilic Actinomycetes / 微生物学通报

Cl~-was used as main negative ion long time for isolation and culture of moderately halophilic or halotolerant actinomycetes, but there are other negative ions such as NO_3~-、SO_4~(2-)、CO_3~(2-)and HCO_3~-in salt lake. Media with only Cl~-could not reflect their living natural environments, which was limited to study on moderately halophilic or halotolerant actinomycetes. In this study, the results show that some negative ion, such as NO_3~-and SO_4~(2-), have not much more selectivity to moderately halophilic or halotolerant actinomycetes, Cl~-can be substituted by NO_3~-and SO_4~(2-). CO_3~(2-)and HCO_3~-has little effect on the genus Nocardiopsis,but have much more on other genera such as Prauserella,Streptomonospora and Saccharomonospora, etc. These results will be some instructive to the isolation and cultivation of moderately halophilic or halotolerant actinomycetes.