Metal Metabolism and Toxicity: Repetitive DNA

Robinson, Nigel J.; Rutherford, Julian C.; Pocock, Mathew R.; Cavet, James

doi:10.1007/0-306-46855-7_16

Cited by 8 publications

(6 citation statements)

References 114 publications

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“…kazusa.or.jp/cyanobase/Synechocystis/mutants/cgi-bin/ comshow.cgi?id = slr2043). This cluster of genes was previously referred to as itzABC [60]. The processes of zinc import and detection of low zinc in Synechocystis PCC 6803 appear similar to E. coli, as described elsewhere (reviewed in [61]) although there are some abnormal requirements for zinc enzymes in cyanobacteria.…”

Section: Comment: Atx1 Copz Copper Metallochaperones and Transport Tmentioning

confidence: 75%

Zn, Cu and Co in cyanobacteria: selective control of metal availability

2003

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Homeostatic systems for essential and non-essential metals create the cellular environments in which the correct metals are acquired by metalloproteins while the incorrect ones are somehow avoided. Cyanobacteria have metal requirements often absent from other bacteria; copper in thylakoidal plastocyanin, zinc in carboxysomal carbonic anhydrase, cobalt in cobalamin but magnesium in chlorophyll, molybdenum in heterocystous nitrogenase, manganese in thylakoidal water-splitting oxygen-evolving complex. This article reviews: an intracellular trafficking pathway for inward copper supply, the sequestration of surplus zinc by metallothionein (also present in other bacteria) and the detection and export of excess cobalt. We consider the influence of homeostatic proteins on selective metal availability.

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Section: Comment: Atx1 Copz Copper Metallochaperones and Transport Tmentioning

confidence: 75%

Zn, Cu and Co in cyanobacteria: selective control of metal availability

2003

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“…However, manufacturing protective pigments comes at a cost. MAAs in Nostoc commune may be 10% of the colony dry weight (Robinson et al 2000) and scytonemin can be 15% of cyanobacterial dry biomass (Büdel et al 1997). In addition, pigments are constantly degrading and need replacement.…”

Section: Effects Of Increasing Precipitation Frequency On Carbon Balamentioning

confidence: 99%

Response of desert biological soil crusts to alterations in precipitation frequency

2003

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Biological soil crusts, a community of cyanobacteria, lichens, and mosses that live on the soil surface, occur in deserts throughout the world. They are a critical component of desert ecosystems, as they are important contributors to soil fertility and stability. Future climate scenarios predict alteration of the timing and amount of precipitation in desert environments. Because biological soil crust organisms are only metabolically active when wet, and as soil surfaces dry quickly in deserts during late spring, summer, and early fall, the amount and timing of precipitation is likely to have significant impacts on the physiological functioning of these communities. Using the three dominant soil crust types found in the western United States, we applied three levels of precipitation frequency (50% below-average, average, and 50% above-average) while maintaining average precipitation amount (therefore changing both timing and size of applied events). We measured the impact of these treatments on photosynthetic performance (as indicated by dark-adapted quantum yield and chlorophyll a concentrations), nitrogenase activity, and the ability of these organisms to maintain concentrations of radiation-protective pigments (scytonemin, beta-carotene, echinenone, xanthophylls, and canthaxanthin). Increased precipitation frequency produced little response after 2.5 months exposure during spring (1 April-15 June) or summer (15 June-31 August). In contrast, most of the above variables had a large, negative response after exposure to increased precipitation frequency for 6 months spring-fall (1 April-31 October) treatment. The crusts dominated by the soil lichen Collema, being dark and protruding above the surface, dried the most rapidly, followed by the dark surface cyanobacterial crusts (Nostoc- Scytonema- Microcoleus), and then by the light cyanobacterial crusts (Microcoleus). This order reflected the magnitude of the observed response: crusts dominated by the lichen Collema showed the largest decline in quantum yield, chlorophyll a, and protective pigments; crusts dominated by Nostoc-Scytonema-Microcoleus showed an intermediate decline in these variables; and the crusts dominated by Microcoleus showed the least negative response. Most previous studies of crust response to radiation stress have been short-term laboratory studies, where organisms were watered and kept under moderate temperatures. Such conditions would give crust organisms access to ample carbon to respond to imposed stresses (e.g., production of UV-protective pigments, replacement of degraded chlorophyll). In contrast, our longer-term study showed that under field conditions of high air temperatures and frequent, small precipitation events, crust organisms appear unable to produce protective pigments in response to radiation stress, as they likely dried more quickly than when they received larger, less frequent events. Reduced activity time likely resulted in less carbon available to produce or repair chlorophyll a and/or protective pigments. Our findings may ...

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“…Any negative effects on phytoplankton will influence the upper trophic levels (Li et al 2006). Therefore, the release of metals into aquatic ecosystems and the toxicity of these metals on phytoplankton species have received considerable attention over the past 20 years (Robinson et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Assessment of growth rate, chlorophyll a fluorescence, lipid peroxidation and antioxidant enzyme activity in Aphanizomenon flos-aquae, Pediastrum simplex and Synedra acus exposed to cadmium

Ran

Liu

et al. 2014

Ecotoxicology

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In this study, the effects of cadmium on the cyanobacterium Aphanizomenon flos-aquae, the green alga Pediastrum simplex and the diatom Synedra acus was evaluated on the basis of growth rate, chlorophyll a fluorescence, lipid peroxidation and antioxidant enzyme activity. The EC50 values (effective concentration inducing 50 % of growth inhibition) of cadmium in A. flos-aquae, P. simplex and S. acus were 1.18 ± 0.044, 4.32 ± 0.068 and 3.7 ± 0.055 mg/L, respectively. The results suggested that cadmium stress decreases growth rate and chlorophyll a concentration. The normalized chlorophyll a fluorescence transients significantly increased at cadmium concentrations of 5.0, 10.0 and 20.0 mg/L, but slightly decreased at concentrations of 0.2, 0.5 and 1.0 mg/L. The chlorophyll fluorescence parameters showed considerable variation among the three species, while lipid peroxidation and antioxidant enzyme activities showed a significant increase. Our results demonstrated that blockage of electron transport on the acceptor side of photosystem II is the mechanism responsible for cadmium toxicity in freshwater microalgae, and that the tolerance of the three species to cadmium was in the order green alga P. simplex > diatom S. acus > cyanobacterium A. flos-aquae.

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Metal Metabolism and Toxicity: Repetitive DNA

Cited by 8 publications

References 114 publications

Zn, Cu and Co in cyanobacteria: selective control of metal availability

Zn, Cu and Co in cyanobacteria: selective control of metal availability

Response of desert biological soil crusts to alterations in precipitation frequency

Assessment of growth rate, chlorophyll a fluorescence, lipid peroxidation and antioxidant enzyme activity in Aphanizomenon flos-aquae, Pediastrum simplex and Synedra acus exposed to cadmium

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