title: Effects of lead accumulation on the Azolla caroliniana-Anabaena association.
abstract: The effect of lead accumulation on photopigment production, mineral nutrition, and Anabaena vegetative cell size and heterocyst formation in Azolla caroliniana was investigated. Plants were exposed to 0, 1, 5, 10, and 20 mg L(-1) lead acetate for ten days. Lead accumulation increased when plants were treated with higher lead concentrations. Results revealed a statistically significant decline in total chlorophyll, chlorophyll a, chlorophyll b, and carotenoids in 5, 10, and 20 mg Pb L(-1) treatment groups as compared to plants with 0 or 1 mg Pb L(-1) treatments. No statistically significant change in anthocyanin production was observed. Calcium, magnesium, and zinc concentrations in plants decreased in increasing treatment groups, whereas sodium and potassium concentrations increased. Nitrogen and carbon were also found to decrease in plant tissue. Anabaena vegetative cells decreased in size and heterocyst frequency declined rapidly in a Pb dose-dependent manner. These results indicate that, while A. caroliniana removes lead from aqueous solution, the heavy metal causes physiological and biochemical changes by impairing photosynthesis, changing mineral nutrition, and impeding the growth and formation of heterocysts of the symbiotic cyanobacteria that live within leaf cavities of the fronds.
authors: Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, 5060 Lakeshore Drive, Bolton Landing, NY 12814, United States; Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, United States. Electronic address: robera4@rpi.edu.
authors: Anne E
authors: AE
authors: Roberts
authors: Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, 5060 Lakeshore Drive, Bolton Landing, NY 12814, United States; Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, United States. Electronic address: boylec@rpi.edu.
authors: Charles W
authors: CW
authors: Boylen
authors: Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, 5060 Lakeshore Drive, Bolton Landing, NY 12814, United States; Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, United States. Electronic address: nierzs@rpi.edu.
authors: Sandra A
authors: SA
authors: Nierzwicki-Bauer
mesh_terms: D017033:Anabaena / Q000187:drug effects* / Q000502:physiology*; D002338:Carotenoids / Q000032:analysis / Q000378:metabolism; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D029624:Ferns / Q000737:chemistry / Q000187:drug effects* / Q000382:microbiology*; D008903:Minerals / Q000032:analysis; D009942:Organometallic Compounds / Q000378:metabolism* / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D013559:Symbiosis
chemical_list: D008903:Minerals; D009942:Organometallic Compounds; D002734:Chlorophyll; D002338:Carotenoids; C008261:lead acetate
keywords: Azolla; Lead accumulation; Phytoremediation; Symbiosis; Toxicology