title: A STUDY OF LIGHT INTENSITY, PERIODICITY, AND WAVELENGTH ON ZOOSPORE PRODUCTION BY PROTOSIPHON BOTRYOIDES KLEBS(1) (2).
abstract: When mature Protosiphon cells were placed in darkness, zoospore production was more extensive and was completed in a shorter time at a temperature of 27 C than at 22 or 15 C. Cool-white fluorescent (Sylvania) light inhibited the process measurably at a radiation intensity of 0.6±10(3) ergsjcm(2) -sec; inhibition was 96% complete at 14±10(3) ergs/cm(2) -sec. For mature cells previously grown under repeated 12-12 hr light-dark cycles, a dark period of approximately 2 hr at 22 C allowed cell division to proceed to a stage such that reillumination did not inhibit continued development of zoospores. Monochromatic light from 402 to approximately -494 nm, as compared to darkness, inhibited zoospore formation; maximal inhibition was at 432-461 nm. In contrast, monochromatic light from 522 to 726 nm stimulated zoospore formation relative to darkness. Synchronous zoospore production was obtained using the following regimes: (A) 12 hr cool-white alternated with 12 hr yellow, (B) 12 hr cool-white alternated with 12 hr blue. Under regime A synchronous zoospore release (following synchronous production) occurred near the end of the yellow irradiation period, while under regime B it occurred near the end of the cool-white irradiation period. The significance of this in terms of photoprocesses and possible photoreceptors is discussed.
authors.affiliation: Department of Biology, University of Alabama, University, Alabama 35486.
authors.forename: J P
authors.initials: JP
authors.lastname: Durant
authors.affiliation: Department of Biology, University of Alabama, University, Alabama 35486.
authors.forename: L
authors.initials: L
authors.lastname: Spratling
authors.affiliation: Department of Biology, University of Alabama, University, Alabama 35486.
authors.forename: J C
authors.initials: JC
authors.lastname: O'Kelley