Reaction of spruce cells toward heavy metals and the influence of culture conditions

BACKGROUND: Plant cell cultures may serve as biosensors for the detection of heavy metals and other toxic substances. Standard culture media and protocols are frequently utilised, but in these media no care is usually taken to control the influence of hormones and nutrients on the reaction of the enzymes or m under consideration as parts of the sensor. The present paper investigates the influence of media composition on the reaction of spruce cells towards heavy metals. METHODS: Spruce cell cultures were grown in a standard medium, either i) alone, ii) containing 0.3% sucrose or iii) containing 3% sucrose and the hormones BAP and NAA. The cell cultures were then incubated in medium with fungal elicitor, H2O2, CdSO4 (50 to 500 microM), or, alternatively, with a standard heavy metal mixture containing 80 microM Na2HAsO4, 150 microM CdSO4 and 200 microM PbCl2. RESULTS: Depending on the nutrient status and hormone availability, large differences in glutathione contents and the GSH/GSSG ratio were observed. However, the cellular redox state seemed to remain more or less constant. Glutathione S-transferase activity was determined with four substrates, and high induction rates for the conjugation of three substrates were observed when hormones were omitted from the media. 1,2-epoxy-nitrophenoxy-propane conjugation was highest in starving cell in the presence of hormones, showing a transient GST induction, with highest rates occurring after 16 hrs following incubation; the induction effect was lost after 24 hrs. CONCLUSION: A medium containing 3% sucrose and both hormones (BAP and NAA) appears to be most favourable for cellular growth as well as the expression of a basis level of detoxification enzymes and antioxidants. With this combination, early responses towards heavy metals at low concentration can be monitored. RECOMMENDATIONS AND PERSPECTIVE: Plant cell cultures are valuable tools for the bioindication of heavy metals and toxic xenobiotics. If standard media and protocols are utilised, the influence of hormones and nutrients on the reaction of the biosensor have to be evaluated thoroughly.     

Levels of lead, cadmium and other elements in mink and otter from Ontario, Canada

Concentrations of Pb, Cd, Cu, Ni, Fe, Zn, Mn, Ca, P, Mg and S were measured in tissues of mink (Mustela vision) and river otter (Lutra canadensis) from five areas of Ontario, Canada. Bone Pb levels in both species were lowest in animals from the collection site most remote from industrial activity and atmospheric deposition of pollutants. Mean liver and kidney Cd levels were also different between collection sites and may reflect natural and/or anthropogenic sources. Copper levels in liver, but not kidney, were elevated in mink and otter from the heavily Cu-contaminated Sudbury region. However, tissue levels did not reflect environmental loading of other metals, such as Fe, Ni and Zn, in the Sudbury area. This may be a function of effective homeostatic regulation in mammals, or low potential for biomagnification of these elements.     

Studies of the effect of simulated acid rain on the ecological equilibrium of the soil system

Introduction to the problem of environmental pollution caused by acid depositions. Presentation of principles of the six-year field experiment with simulated acid rain. Short characteristics of particular parts of the series of papers.     

The importance of the will to improve: how ‘sustainability’ sidelined local livelihoods in a carbon-forestry investment in Uganda

This paper describes a ‘win–win’ discourse on local sustainable development and global climate change mitigation regarding Kachung, a Swedish–Norwegian climate forestry investment in Uganda certified under the Clean Development Mechanism (CDM). In many ways, this investment is a typical example of how private interests and capital accumulation are prioritised over local concerns in natural resource management under neoliberalism. This study, however, indicated that investors had genuine intentions of creating mutual benefits for the global environment and local people. Drawing on Li (2007), we show that this ‘will to improve’ was nevertheless constructed in ways that resulted in prioritisation of global climate change mitigation over local context-specific concerns.

We identify three core factors making the win–win discourse around Kachung plantation especially resilient: (i) the perceived urgency of climate change mitigation, (ii) the apolitical framing of ‘sustainability’ as an environmental issue that can be fixed through external technical interventions and (iii) the devaluation of local and context-specific knowledge. We end by suggesting that research on the neoliberalisation of nature focus more on analysing the rationales behind specific interventions. This would leave us better equipped to suggest how such interventions should be modified to produce true wins for local contexts.