KOPS - Das Institutionelle Repositorium der Universität Konstanz

Effects of nanomolar copper on water plants : comparison of biochemical and biophysical mechanisms of deficiency and sublethal toxicity under environmentally relevant conditions

Effects of nanomolar copper on water plants : comparison of biochemical and biophysical mechanisms of deficiency and sublethal toxicity under environmentally relevant conditions

Zitieren

Dateien zu dieser Ressource

Prüfsumme: MD5:7370ef44fccc79d8a25eb0198e87ec57

THOMAS, George, 2014. Effects of nanomolar copper on water plants : comparison of biochemical and biophysical mechanisms of deficiency and sublethal toxicity under environmentally relevant conditions [Dissertation]. Konstanz: University of Konstanz

@phdthesis{Thomas2014Effec-26929, title={Effects of nanomolar copper on water plants : comparison of biochemical and biophysical mechanisms of deficiency and sublethal toxicity under environmentally relevant conditions}, year={2014}, author={Thomas, George}, address={Konstanz}, school={Universität Konstanz} }

eng Thomas, George Thomas, George 2014-03-18T07:51:23Z 2014 Effects of nanomolar copper on water plants : comparison of biochemical and biophysical mechanisms of deficiency and sublethal toxicity under environmentally relevant conditions The thesis is a comprehensive study of the effects of nanomolar Cu (from deficiency, through optimal to toxicity) on Ceratophyllum demersum L. under environmentally relevant conditions. The thesis also deals with an investigation of the contribution of Cd and Ni toxicity to the almost complete absence of macrophytes in lake Ammelshain and in soft and hard water in general. Effects of nanomolar heavy metal stress on Ceratophyllum demersum L. The plant responses to Cu stress during six weeks of treatment were studied under high light (HL) and low light (LL) conditions. Growth was optimal in the range of 10-20 nM Cu. In HL, damage to the PSII RC was the first target of Cu toxicity, followed by damage to the regulation of heat dissipation (NPQ). Then electron transport through PSII was inhibited, followed by decrease in chlorophyll concentration. In LL, damage to the light harvesting complex (LHC) was associated with replacement of Mg by Cu in the chlorophyll of the LHCII. This caused a denaturation of the LHCII trimers to monomers, which likely further decreased the NPQ. Cu was mainly stored in the vein at all concentrations. But at toxic levels, Cu was additionally sequestered to the epidermis and mesophyll until export from vein was inhibited at highest Cu. This was accompanied with Zn uptake inhibition. Only the highest Cu concentrations led to elevated phytochelatin levels. We also found that the induction of phytochelatins is not proportional to metal concentration, but has a specific threshold for each phytochelatin species.<br /><br /> During Cu deficiency in HL conditions, a complete stop of growth was observed at “0” nM Cu after six weeks. Electron flow through PSII decreased from the second week, followed by pigment decrease and an increase in NPQ. The lack of high affinity Cu transporters resulted in a release of Cu from the plants below 10 nM Cu supply. A re-distribution of Zn was observed in the plant tissues at “0” nM Cu. In LL conditions, the deficiency stress was not as strong as for HL. The lack of electron transport through the PSII at deficient Cu was most likely caused by limited Cu loading of plastocyanin. Further, a reduction in the pigments added to the decrease in photosynthesis, resulting in reduced starch formation and oxygen production. Effects of Cd and Ni toxicity to Ceratophyllum demersum L.<br /><br /> An investigation was performed on an oligotrophic lake to study whether heavy metal concentrations were responsible for the nearly complete lack of submerged macrophytes in the lake. Individually nontoxic cadmium (3 nM) and slightly toxic nickel (300 nM) concentrations became highly toxic when applied together in soft water. This kind of synergistic heavy metal toxicity may have a greater effect on the ecosystems than estimated so far. Phosphate limitation, which is a well-known problem in freshwater habitats, further enhanced the toxicity in soft water. Since the high water hardness in the lake limited the toxicity of these metal concentrations, the macrophytic growth inhibition in this lake might have additional reasons deposit-license

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

Thomas_269297.pdf 224

Das Dokument erscheint in:

KOPS Suche


Stöbern

Mein Benutzerkonto