Experiments in which chloroplasts were washed with tris and tricine buffers at different pH's indicated that the non-protonated (uncharged) form of tris was inhibitory to the Hill reaction while the protonated form of tris and the zwitterionic forms of tricine were non-inhibitory. Buffers analogous to tris and tricine gave similar results. Photoreduction of NADP could be restored to the inhibit...

Cultures of escherichia coli growing exponentially in Trisacetate medium were subjected to nutritional shift-up and the pool size of guanosine 5'-3'-diphosphate-3'diphosphate (ppGpp) as well as the rates of protein synthesis and net RNA synthesis were determined. In the shift to a rich medium (glucose plus 19 amino acids plus hypoxanthine) the basal level of ppGpp falls immediately with a decay...

The slow voltage dependent calcium channels have been described in skeletal muscle fibres of adult frogs and rats (Sanchez and Stefani 1978; Donaldson and Beam 1983). Some data have suggested that they may participate in excitationcontraction coupling (ECC) (Beam et al. 1986; Ildefonse et al. 1985; Rios et al. 1986). However, some other investigations have shown the independence of ?"'' tion of...

The present study was aimed to test the efficacy of adding vitamins C or E to Tris-fructose-egg yolk diluent to increase Awassi ram sperm storage period at 5 ˚C. Semen samples from six mature Awassi rams were used in this study. The semen samples were diluted by Tris-glucose-egg yolk. Diluted semen sample was divided into three parts. The first part was added with 0.9 mg mL-1 vitamin...