Project description:Two-bottle choice tests were used to assess the taste preferences of 8 male and 8 female rats from 3 outbred strains (SD, LE, WI) and 11 inbred strains (BN, BUF, COP, DA, Dahl-S, F344, FHH, LEW, Noble, PVG, SHR). Each rat received a series of 109 48-h tests with a choice between water and a "taste solution". Four to eight concentrations of the following compounds were tested: NaCl, CaCl2, NH4Cl, KCl, MgCl2, saccharin, sucrose, ethanol, HCl, citric acid, quinine hydrochloride (QHCl), caffeine, denatonium, monosodium glutamate (MSG), Polycose, corn oil, and capsaicin. Strain differences (p<0.001) were observed in preferences for at least one concentration of all compounds tested except denatonium (p=0.0015). There were also strain differences in the following ancillary measures: fungiform papillae number, water intake, food intake, and body weight. There were sex differences in food intake and body weight but no concerted sex differences in any of the other measures, including preferences for any taste solution. This comprehensive source of information can be used to guide the choice of appropriate rat strains and taste solution concentrations for future genetic studies.
Project description:In bacteria, one paradigm for signal transduction is the two-component regulatory system, consisting of a sensor kinase (usually a membrane protein) and a response regulator (usually a membrane protein) and a response regulator (usually a DNA binding protein). The EnvZ/OmpR two-component system in S. Typhimurium responds to osmotic stress and regulates expression of outer membrane proteins. Furthermore, bacteria were believed to regulate pH by acidifying after external acid stress, then immediately recovering. Using a pH-sensor in single living cells, we show that S. Typhimurium maintain an acidic cytoplasm under sucrose-driven osmotic stress which requires OmpR. Thus, we set out to identify the OmpR targets of S. Typhimurium under osmotic stress.