77°K fluorescence spectra of dark-grown Euglena gracilis subjected to short light flashes

The first steps of chlorophyll synthesis in dark-grown Euglena gracilis have been studied by giving light flashes of short duration to etiolated cells and measuring their fluorescence emission spectra at 77°K. In dark-grown cells the maximum of emission lies at 636 nm with a secondary band at 657 nm. After a single actinic flash the 657 nm emission decreases and a new peak appears at 675 nm. From flash to flash, given every 3 min, the emission at 675 nm increases and shifts progressively to 685 nm, while the emission at 636 nm decreases. After about 60 flashes a band centered at 715 nm appears which thereafter shifts toward 730 nm. By about 1000 flashes the 77°K emission spectrum was found typical of normal light-grown Euglena, with a maximum at 720-730 nm and secondary emission bands at 685 and 695 nm. © 1975.