Precautions for routine use of INT-reductase activity for measuring biological activities in soil and sediments

Toxicological effects of cobalt on common carp: oxidative stress, ionic imbalance, fatty acid disruption, and gill histopathology

Cobalt (Co) is an essential element to fish and other organisms that become toxic at high concentrations. This element is emerging as a concerning pollutant in water bodies, potentially endangering the health of marine biota. The aim of this study was to investigate the short-term subcellular toxicity of cobalt in the common carp Cyprinus carpio (0, 1.13, 11.34, 22.68 and 45.37 µg/L of Co2+ for 72 h), with emphasis on oxidative balance (enzymatic and non-enzymatic antioxidants), fatty acid composition, Na+K+/Mg2+ATPases activities and histopathological changes. Co exposure increased the levels of the ferric reducing antioxidant power, hydrogen peroxide, malondialdehyde and protein carbonyl along with enzymatic and non-enzymatic antioxidant-related markers. The observed prooxidant-antioxidant imbalance in exposed fish was solidified by histological sections confirming alterations in the histomorphological structure of C. carpio gills. Results showed that increases in Co2+ exposure of fish altered the ATPases activities revealing changes in osmoregulation. Additionally, the analysis of fatty acids (FA) underscored shifts in the fish's fatty acid profile, which is indicative of Co2+ impact on C. carpio overall metabolism and immune response. Significant changes occurred in some major FA which were associated with lipid peroxidation increase and the inhibition of Na+K+ and Mg2+ ATPases activities. Overall, the current results suggest that the mechanism of Co2+ toxicity involves oxidative damage, disruption of ionic balance, cellular homeostasis and the normal physiological function of the fish gills.

Comparison of microbial and meiofaunal community analyses for determining impact of heavy metal contamination

The impact of long-term heavy metal contamination on soil communities was assessed by a number of methods. These included plate counts of culturable bacteria, community level physiological profiling (CLPP) by analysis of the utilization of multiple carbon sources in BIOLOG plates, community fatty acid methyl ester (C-FAME) profiling and dehydrogenase enzyme activity measurements. These approaches were complemented with microscopic assessments of the diversity of the nematode community. Samples from two sites with different histories of heavy-metal input were assessed. Major differences in microbial and meiofaunal parameters were observed both between and within the sites. There was a large degree of congruence between each of the microbiological approaches. In particular, one sample appeared to be distinguished by a reduction in culturable bacteria (especially pseudomonads), limited response to carbon sources in CLPP, and major differences in extracted fatty acid profiles. The use of multivariate analysis to examine the relationship between microbial and physicochemical measurements revealed that CLPP and plate counts were useful for determining the gross effect of metals on soil microbial communities, whereas proportions of metal-resistant bacteria and dehydrogenase activity differentiated between the two sites. Copper and zinc concentrations and pH all showed significant correlation with the microbial parameters. Nematode community structure was affected to a greater extent by soil pH than by metal content, but the within-site rankings were the same as those achieved for microbiological analyses. The use of these methods for field evaluation of the impact of industrial pollution may be possible provided care is taken when interpreting the data.