Changes at transcriptional level in the rat liver following whole-body X-irradiation

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New fluorometric method for estimation of citrovorum factor

A rapid method for the identification and estimation of CF is described. After separation on paper chromatograms, CF gives a grayish blue fluorescence under ultraviolet light on reaction with acidified orcinol. The compound formed is eluted with sodium bicarbonate solution and the fluorescence is quantitatively measured in a Klett fluorometer. This method has been used to estimate enzymically formed CF in an in vitro system of chicken liver homogenate. The possibility of developing the fluorescence in solution has also been demonstrated. Even 100 mµg of CF is detectable visually on paper chromatograms. In solution, 0.5–5.0 µg of CF can be assayed with Klett fluorometer

Ineffectiveness of rifampicin in inhibiting RNA synthesis in Escherichia coli and T<SUB>4</SUB>-infected Escherichia coli cells after exposure to ultraviolet radiation

Residual RNA synthesis in Escherichia coli cells and T<SUB>4</SUB>-infected E. coli cells exposed to ultraviolet radiation is insensitive to rifampicin. On the other hand, residual RNA synthesis in these cells after gamma irradiation is further inhibited by rifampicin. The specific effect exerted by ultraviolet irradiation on transcription seems to arise from alterations in the DNA structure rather than in bacterial RNA polymerase since RNA synthesis in ultraviolet-irradiated E. coli cells infected with unirradiated T<SUB>4</SUB> is sensitive to rifampicin

Action of hydrocortisone at a translational level in the rat liver

Administration of hydrocortisone to adrenalectomised rats elevated levels of both free and membrane-bound polysomes in liver and led to marked shifts in their sedimentation profiles in favour of heavier polysomes. The rate of nascent polypeptide formation was also found to be enhanced in response to the hormone but this effect was mainly confined to the site of free polysomes. These results suggest that besides its well-known potentiating action at the transcription level, the hormone elicits selective stimulatory response at the translation level