Effects of zinc toxicity on the nitrogen-fixing cyanobacterium Anabaena sphaerica-ultastructural, physiological and biochemical analyses
| Autor: | Arun Kumar Mishra, Sindhunath Chakraborty |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
Chemistry Health Toxicology and Mutagenesis chemistry.chemical_element General Medicine Zinc 010501 environmental sciences medicine.disease_cause Photosynthesis 01 natural sciences Pollution Amino acid Biochemistry Toxicity Zinc toxicity Nitrogen fixation medicine Environmental Chemistry Oxidative stress 0105 earth and related environmental sciences Heterocyst |
| Zdroj: | Environmental science and pollution research international. |
| ISSN: | 1614-7499 |
| Popis: | The current study describes the mechanisms of zinc toxicity in the cyanobacterium Anabaena sphaerica after eight days treatment with 10 mg L−1 ZnCl2. The application of zinc not only showed elevated accumulation of the metal inside the cells but also exhibited devastating impacts on the cell numbers, morphology, and ultrastructure of A. sphaerica. The effects of zinc on the pigments contents, oxygen evolution rate, Fv/Fm, electron transport rate, and carbohydrate content were also evaluated in A. sphaerica. Moreover, zinc adversely affected nutrient uptake and the cellular energy budget in the test cyanobacterium which in turn hampered heterocyst development and nitrogen fixation. Alongside, the cyanobacterium experienced zinc-mediated non-competitive inhibition of glutamine synthetase activity, curtailed synthesis of amino acids and proteins. Furthermore, drastically reduced total lipid and increased unsaturated lipid contents were also the prominent characteristics of zinc stressed A. sphaerica. Most importantly, zinc stress caused severe damages to the protein, lipid, and DNA by triggering hydrogen peroxide generation and accumulation of oxidized glutathione. Therefore, excess zinc is highly toxic to the cyanobacterium A. sphaerica, and the mechanisms of its toxicity followed a cascade of events including oxidative stress mediated geopardisation of growth and ultrastructure, metabolic derangements, and macromolecular damages. |
| Databáze: | OpenAIRE |
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