Factors Controlling the Production of Lysogenic Cultures of B. megatherium

(1) The proportion of infected B. megatherium cells which develop lysogenic colonies depends on the number and kind of infecting virus particles and on the culture medium in which the cells are growing. (2) Cells infected with 100 or more T virus particles (from megatherium 899) in yeast extract peptone disintegrate, produce very few virus particles, and less than one lysogenic colony per 10⁷ infected cells. Cells infected with one or a few particles produce 500 to 1000 virus particles each and about 30 lysogenic colonies per 10⁷ infected colonies. (3) T phage obtained from lysogenic magatherium KM cultures produces many more lysogenic cells than does the original megatherium 899 virus. (4) Cells infected with megatherium 899 T virus in peptone medium and then transferred to asparagine medium give rise to 10⁶ lysogenic colonies per 10⁷ infected cells and this transformation will occur even after the infected cells have been in peptone for 60 to 90 minutes and are beginning to produce virus particles. (5) Continued growth of KM strain with either C or T virus from megatherium 899 for several hundred generations in the steady state apparatus results in a lysogenic strain which produces several different types of virus.     

Tissue uptake of catechol and indole amino acids histochemical studies on the rat iris

Summary Rat irises exposed to DOPA in vitro and subsequently treated with the histochemical technique of Falck and Hillarp for catecholamines show accumulation of a fluorescent formaldehyde condensation product within the capillary endothelial cells. A similar accumulation was observed when rat irises were exposed to 5-OH-Tryptophan and -methyl-dopa but not after exposure to the corresponding amines. Fluorescent products were also observed in the same cells when control irises were treated with the trihydroxyindole histochemical reaction. It is concluded that certain catechol and indole amino acids accumulate within the endothelial cells of the rat iris capillaries in a manner similar to that observed in brain capillaries. Furthermore, small amounts of DOPA are probably present within these cells normally.