What determines the color of the light of luminous animals?

Abstract

A luminous ostracod (species unknown) occurs in the sea about Jamaica, B. W. I., whose light is more yellow than the Japanese ostracod, Cypridina hilgendorfii. Like the Japanese form, the Jamaican form exhibits the luciferin-luciferase reaction, i. e., a hot water non-luminous extract of the luminous gland allowed to cool (containing luciferin), will give light when mixed with a cold water extract of the luminous gland allowed to stand until its luminescence completely disappears (containing luciferase). Moreover, luciferin from the Jamaican species will luminesce if mixed with the luciferase of the Japanese species, and vice versa. By carrying out the four possible “crosses” one may determine whether the color of the resulting light is controlled by the ostracod supplying the luciferin or the luciferase.

The following results were obtained:

Japanese luciferase × Japanese luciferin—bluish light.

Japanese luciferase × Japanese luciferin—yellowish light.

Japanese luciferase × Japanese luciferin—yellowish light.

Japanese luciferase × Japanese luciferin—bluish light.

It is apparent that the luciferase determines the color of the light.