Light Induced Concentration Changes of Adenosine-Triphosphate in Phycomyces Sporangiophores

Abstract

ATP concentrations following the induction of positive light-growth responses in sporangiophores of the fungus Phycomyces blakesleeanus by blue light stimuli were measured by means of the luciferin-luciferase assay. The ATP concentration in the light-sensitive growing zone increased 30-50% within 30 seconds after the start of a light stimulus and returned to normal adapted level within 1 minute after stimulation. The ATP concentration was constant for any level of light adaptation and was uniform along the length of sporangiophores even though the light sensitivity was confined to a growing zone less than 5 mm long. It is suggested that one of the initial biochemical steps after a light stimulus is the production of extractable ATP.