title: Effects of chromium on photosynthetic and photoreceptive apparatus of the alga Chlamydomonas reinhardtii.
abstract: Chromium is a highly toxic non-essential metal for microorganisms and plants. Due to its widespread industrial use, chromium (Cr) has become a serious pollutant in diverse environmental settings. The presence of Cr leads to the selection of algal populations able to tolerate high levels of Cr compounds. The diverse Cr-resistance mechanisms displayed by microorganisms include biosorption, diminished accumulation, precipitation, reduction of Cr(6+) to Cr(3+), and chromate efflux. In this paper we describe the effects of Cr(6+) (the more toxic species) on the photosynthetic and photoreceptive apparatus of the fresh water unicellular alga Chlamydomonas reinhardtii. We measured the effect of the heavy metal by means of in vivo absorption microspectroscopy of both the thylakoid compartments and the eyespot. The decomposition of the overall absorption spectra in pigment constituents indicates that Cr(6+) induced a complete pheophinitization of the chrorophylls and a modification of the carotenoids present in the eyespot only when its concentration is equal or greater than 10 microM. Due to this low tolerance level, C. reinhardtii could be used as indicator of Cr pollution, but it is not feasible for bioremediation purposes.
authors.affiliation: Departmento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA, Buenos Aires, Argentina.
authors.forename: M Cecilia
authors.initials: MC
authors.lastname: Rodríguez
authors.forename: Laura
authors.initials: L
authors.lastname: Barsanti
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Passarelli
authors.forename: Valter
authors.initials: V
authors.lastname: Evangelista
authors.forename: Visitacion
authors.initials: V
authors.lastname: Conforti
authors.forename: Paolo
authors.initials: P
authors.lastname: Gualtieri
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000187:drug effects* / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002857:Chromium / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D020524:Thylakoids / Q000187:drug effects / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002857:Chromium; D002734:Chlorophyll; C037184:chlorophyll b; D000077194:Chlorophyll A