title: Near-UV activation of yeast growth.
abstract: Near-UV radiation (337 nm) at fluences of 2-10 kJ m-2 activates, during the lag-phase, subsequent growth of the yeast Candida guilliermondii. Photostimulation occurs only after a temperature-dependent time interval (1-2 h) between short-period irradiation and the onset of cell growth on a nutrient medium. A photoactivated enzymatic synthesis of an intermediate metabolite regulating cell growth is proposed as the cause of the biochemical changes responsible for the photostimulatory effect. On the basis of the observed disappearance of photostimulation after adding para-chlorphenylalanine (a specific inhibitor of serotonin synthesis), serotonin is suggested to act as the active metabolite. The regulatory function of serotonin is confirmed by the stimulatory effect of exogenous serotonin and its dependence on concentration, which resembles the dependence on near-UV fluence.
authors.affiliation: Department of Biophysics, Faculty of Biology, State University of Moscow, U.S.S.R.
authors.forename: N S
authors.initials: NS
authors.lastname: Belenikina
authors.forename: M G
authors.initials: MG
authors.lastname: Strakhovskaya
authors.lastname: Fraikin GYa
mesh_terms: D002175:Candida / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects*; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D010134:Fenclonine / Q000494:pharmacology; D007700:Kinetics; D012701:Serotonin / Q000494:pharmacology; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D012701:Serotonin; D010134:Fenclonine