Cell surface NADH oxidase activity of brine shrimp oscillates with a period of 25 min and is entrained by light

Plants have a surface NADH oxidase that measures time by oscillating with a 24-min period. The period is synchronized by light. With plants, a new max imum is observed exactly 12 min after the beginning of the light exposure. These experiments were to determine if animals exhibited a cell surface NAD H oxidase having a similar periodicity and to answer the question, does the periodicity in animals respond to tight! Using brine shrimp as a model, th e findings show that plants and animals exhibit similar oscillating NADH ox idase activity and that the periodicity in this invertebrate animal does re spond to light. Brine shrimp were grown for two to three days and transferr ed to darkness for 45 min. After return to light for one min, NADH was adde d and measurements of NADH oxidation were recorded over 50 min. The brine s hrimp exhibited a cell surface NADH oxidase that oscillated with a period o f 25 min. After being subjected to light, the brine shrimp showed a new max imum in NADH oxidation between 12 to 13 min after the beginning of the tigh t exposure and again at 37 min and at 25 min intervals thereafter. The find ings demonstrate that the periodic oscillations in NADH oxidation of brine shrimp are light entrainable.