Prohibitin is required for transcriptional repression by the WT1-BASP1 complex.

The Wilms' tumor-1 protein (WT1) is a transcriptional regulator that can either activate or repress genes controlling cell growth, apoptosis and differentiation. The transcriptional corepressor BASP1 interacts with WT1 and mediates WT1's transcriptional repression activity. BASP1 is contained within large complexes, suggesting that it works in concert with other factors. Here we report that the transcriptional repressor prohibitin is part of the WT1-BASP1 transcriptional repression complex. Prohibitin interacts with BASP1, colocalizes with BASP1 in the nucleus, and is recruited to the promoter region of WT1 target genes to elicit BASP1-dependent transcriptional repression. We demonstrate that prohibitin and BASP1 cooperate to recruit the chromatin remodeling factor BRG1 to WT1-responsive promoters and that this results in the dissociation of CBP from the promoter region of WT1 target genes. As seen with BASP1, prohibitin can associate with phospholipids. We demonstrate that the recruitment of PIP2 and HDAC1 to WT1 target genes is also dependent on the concerted activity of BASP1 and prohibitin. Our findings provide new insights into the function of prohibitin in transcriptional regulation and uncover a BASP1-prohibitin complex that plays an essential role in the PIP2-dependent recruitment of chromatin remodeling activities to the promoter.

Electrophysiological properties of Hensen's cells investigated in situ.

Tight-seal whole-cell patch clamp recordings were obtained in situ from supporting Hensen's cells within the intact organ of Corti of the adult guinea pig. In normal phosphate buffer solution we estimated 20-50 cells to be coupled by gap junctions to the cell under the patch pipette. In the presence of 1 mM octanol, an uncoupling agent, it was possible to identify an outward current which activated upon depolarization above -20 mV and approached saturation above 70 mV. An inward current was seen with hyperpolarizations below -80 mV. These are broadly similar to the currents of Hensen's cells in vitro. Measured differences of the underlying conductance indicate that the currents are sensitive to the procedure used to isolate cells.

Fate of Salmonella newport and Salmonella typhimurium Inoculated into Summer Sausage 1.

Various fermentation schedules and finishing temperatures used in the summer sausage industry were investigated for their ability to eliminate Salmonella newport or Salmonella typhimurium inoculated into raw ingredients during the formulation phase of production. Summer sausage was produced with and without the aid of a starter culture. Use of the starter culture, a Lactobacillus plantarum strain, provided for a more rapid fermentation and subsequent decrease in pH. Elimination of Salmonella was dependent upon the initial contamination level, serotype involved, rate of fermentation and processing temperature.

Fate of Salmonella Inoculated into Beef for Cooking.

D-values for Salmonella in a ground beef system were established at 125, 135 and 145 F (51.6, 57.2 and 62.7 C). The D-values determined at these temperatures were 61-62, 3.8-4.2 and 0.6-0.7 min, respectively. These values were used to develop a processing table that insured elimination of 10 million inoculated Salmonella in the center of beef roasts at temperatures sufficiently low to maintain the characteristic red color of "rare" roast beef. The effectiveness of the processing values in eliminating 107 Salmonella was confirmed by processing inoculated beef roasts under commercial conditions. Additional processing procedures necessary to insure elimination of Salmonella from the surface of dry roasted beef were also developed, since it was found that Salmonella could survive on the dry roasted beef surfaces under some circumstances.