Andrew R. Walsh

Assessment of a glutathione S-transferase and related proteins in the gill and digestive gland of Mytilus edulis (L.), as potential organic pollution biomarkers

The response of the glutathione S-transferase (GST, EC 2.5.1.18) and related proteins of Mytilus edulis to environmental pollution load was assessed. Mussels were reciprocally transplanted between an industrial estuary (Douglas), a rural estuary (Youghal) and a m arine site (Bantry). In addition, m ussels were sam pled along a pollution gradient in an estuary receiving leather tannery effluent (Colligan). These latter m ussels were previously shown to be subject to oxidative stress resulting from the discharges. GST specific activity of cytosolic extracts from the gill and digestive gland tissues was determ ined for all anim als. Specific activity was shown to vary significantly in anim als from different sites, with highest specific activity always observed in sam ples (local and transplanted) taken from the industrial site. By com parison, the m ussels exposed to tannery discharges displayed no significant alteration in GST specific activity. Total intracellular glutathione (GSH) was also determ ined for sam ples taken from the Douglas and Youghal estuaries but no correlation with pollution load was observed. Using FPLC analysis, we observed no specific effect on the relative levels of the GST and the individual GST related proteins in gill or digestive gland sam ples from local or reciprocally transplanted anim als from Douglas or Youghal. The increase in GST specific activity observed in samples from the industrial estuary are indicative of a possible, specific inductive agent at this site. The results from the tannery site, by com parison, indicate that general oxidative stress does not result in elevated G ST specific activity in M. edulis.The response of the glutathione S-transferase (GST, EC 2.5.1.18) and related proteins of Mytilus edulis to environmental pollution load was assessed. Mussels were reciprocally transplanted between an industrial estuary (Douglas), a rural estuary (Youghal) and a m arine site (Bantry). In addition, m ussels were sam pled along a pollution gradient in an estuary receiving leather tannery effluent (Colligan). These latter m ussels were previously shown to be subject to oxidative stress resulting from the discharges. GST specific activity of cytosolic extracts from the gill and digestive gland tissues was determ ined for all anim als. Specific activity was shown to vary significantly in anim als from different sites, with highest specific activity always observed in sam ples (local and transplanted) taken from the industrial site. By com parison, the m ussels exposed to tannery discharges displayed no significant alteration in GST specific activity. Total intracellular glutathione (GSH) was also determ ined fo...

Chromium speciation in tannery effluent—II. Speciation in the effluent and in a receiving estuary

Abstract The forms and transformations of chromium were characterised in the effluent of an Irish tannery before and after discharge into an estuary. The three primary effluent streams in the tannery were studied, i.e. the chrome and sulphide streams and the final composite effluent. Chromium was fully speciated in the final effluent, the discharge plume, and in the estuary outside discharge periods. The partitioning of chromium was also studied in the sediments, and transformations due to the remobilisation and oxidation of Cr(III) were followed. These data were compared to a reference site. Mixing of the chrome and sulphide streams resulted in the binding of Cr(III) to organic ligands, notably proteins. The speciation of chromium in the final effluent was dominated by Cr(III) particulates with a mean concentration of 72.4 mg Cr 1 −1 . Some 80–90% of these particulates were inorganic while 10–20% were bound to organic ligands. Dissolved concentrations averaged 3.6 mg 1 −1 at pH 10. However, a 45% fall in dissolved Cr(III) was recorded after lowering the pH of the final effluent to that of the receiving waterway, i.e. pH 7.6–8.1. Approximately 50% of the remainder was determined to be bound to proteinaceous ligands with 50% bound to stable organic ligands. However, only the latter species was detectable in the water column outside discharge periods. Low levels of dissolved organic Cr(III) were also found to leach from both control and contaminated sediments, although concentrations were higher in the contaminated sediments. Cr(VI) was undetectable in the estuary ( −1 ) and local sediments were found not to oxidise Cr(III) in the effluent. In comparison, a number of sediments obtained from other sites readily oxidised experimentally added Cr(III) in the tannery effluent matrix. Elevated levels of organic and inorganic chromium in suspended solids were detectable at all sites studied in the contaminated estuary. Sediment Cr concentrations corrected for grain size were also elevated at all sites with highest concentrations being associated with fine grain sediments. However, total Cr concentrations in the sediments were relatively low compared to other tannery contaminated sites due to good dispersion of the effluent in the estuary.

Chromium speciation in tannery effluent—I. An assessment of techniques and the role of organic Cr(III) complexes

Abstract Three methods of chromium speciation were assessed in relation to possible interferences from Cr(III)-organic complexes. They were, namely: 1,5-diphenyl-carbazide (DPC) spectrophotometry, organic extraction with methyl isobutyl ketone (MIBK) and co-precipitation with iron and bismuth salts. Initially, a number of organic ligands, i.e. proteins, amino acids and organic acids were reacted with Cr(III) and only those complexes with solubility levels above that of ionic Cr(III) were assessed further. The spectrophotometric method was found to suffer minor interferences which were attributable to a non-specific turbidity effect. In comparison, two methods of MIBK extraction were found to suffer severe interferences with Cr(III)-protein complexes. Also, co-precipitation with iron salts resulted in high levels of contamination by Cr(III)-organic complexes in the ionic chromium fractions. Due to the poor solubility of bismuth salts, this method was discarded. The results demonstrate that chromium speciation in the presence of organic complexes can lead to erroneous results. However, with recognition of the presence of such complexes, corrections can be made. Since the co-precipitation behaviour of organic Cr(III) appears to be relatively specific, a scheme is described for the speciation of Cr(III) in tannery contaminated waterways. In addition, it is recommeded that a separate determination of Cr(VI) is conducted using a modification of the DPC method.

The Accumulation of chromium by mussels Mytilus edulis (L.) as a function of valency, solubility and ligation

Abstract Mussels exposed to different forms of chromium for 4 weeks preferentially accumulated the metal in the digestive gland, irrespective of the form of chromium employed. Accumulation rates were in the following order: Cr(III)-albumen > tannery effluent Cr(III) > Cr(OH) 3 > Cr(VI) > Cr(III)-citrate. In the Cr(III)-albumen, Cr(VI) and Cr(OH) 3 exposure groups, 23, 23 and 27%, respectively, of the total chromium was found in the cytosolic fraction of the digestive gland. This cytosolic chromium component was found to be largely associated with a medium to low molecular weight fraction in the digestive gland, for both Cr(III)-albumen and Cr(VI) exposed mussels. In contrast, the majority of chromium was bound to a high molecular weight component in the gill. The results indicate that Cr(III) is generally more bio-available than Cr(VI) to Mytilus edulis , although ligation was found to be critical. Evidence is also provided to show that Cr(III) bound to proteins in tannery waste is likely to be responsible for the high levels of accumulation in the tissues of aquatic animals close to tannery effluent outfalls.

The single-crystal electronic and electron spin resonance spectra of copper(II) doped bis(2,2′-bipyridyl)nitritozinc(II) nitrate and bis(2,2′-bipyridyl)nitritocopper(II) tetrafluoroborate: a fluxional CuN2N′2O2 chromophore

The single-crystal e.s.r. spectra and polarised electronic spectra of the copper(II) doped [Zn(bipy)2(ONO)][NO3] system are shown to be closely comparable to those previously reported for [Cu(bipy)2(ONO)][NO3]. The observation of more than four copper hyperfine lines in the single-crystal e.s.r. spectrum measured in the approximate bc plane is consistent with a two-dimensional misalignment of the CuN2N′2O2 chromophore and the temperature variability of the g and A factors are consistent with a two-dimensional fluxional model of the CuN2N′2O2 chromophore with a distorted square-pyramidal 4 + 1 + 1* structure and not with static disorder. This suggests that the structures of [Cu(bipy)2(ONO)][NO3] and [Cu(bipy)2(ONO)][BF4] are not genuine static stereochemistries of the copper(II) ion, but arise as a consequence of the fluxional model and are best referred to as pseudo cis distorted-octahedral structures. The electronic properties of 0.1–100% copper(II) doped [Zn(bipy)2(ONO)][NO3] are shown to be independent of the copper(II) concentration, and this suggests that the structure of the doped CuN2N′2O2 chromophore is independent of the structure of the ZnN2N′2O2 chromophore of the zinc host lattice, but correlates with the known structure of the [Cu(bipy)2(ONO)][NO3] complex, an example of the Non-co-operative Jahn–Teller Effect. The electronic reflectance spectrum of [Cu(bipy)2(ONO)][BF4] is closely comparable to that of the nitrate, despite having a significantly different, (4 + 1 + 1*) type, fluxional CuN4O2 chromophore structure.

The toxicity of leather tannery effluent to a population of the blue mussel Mytilus edulis (L.)

The toxicity of leather tannery effluent affecting a population of Mytilus edulis in the Colligan estuary, Ireland was investigated. At the whole animal level, the growth, condition and chromium concentrations were measured in transplanted, local and control mussels. The fitness of the mussels was assessed by their tolerance to aerial exposure. At the cellular level, the degree of lipid peroxidation was measured in the tissues of field sampled mussels. In addition, mussels were exposed in the laboratory to components of the effluent thought likely to enduce peroxidation, i.e. Cr(VI), Cr(III)--protein and the fungicide, Busan 30WB® containing 2-(thiocyanomethylthio) benzothiazole (TCMTB). The growth, condition and chromium concentrations of transplanted mussels were significantly higher than controls after 1 year of exposure. The fitness of mussels at most sites in the Colligan estuary was comparable to the controls except those closest to the tannery outfall. At the cellular level, lipid peroxidation was demonstrated in the digestive cells of field sampled mussels, while in laboratory exposures Busan 30WB® was found to enduce lipid peroxidation in the digestive gland and amoebocyte proliferation in the gill. Cr(VI) and Cr(III)--protein exposure, by comparison, gave a negative peroxidative response. The results indicate that the enhanced growth and condition seen may be due to the high nutritive content of the effluent while the lipid peroxidation observed was reasoned to be a result of fungicide exposure. Chromium toxicity, however, could not be detected, although such an effect could not be ruled out

Core–Satellite Strategies: Combining Stability and Opportunity in an ETF Portfolio

So-called core-satellite strategies have gained popularity among asset managers seeking to combine strict risk control with opportunities to create alpha through active management. Traditionally core satellite portfolios consist of a passively managed core around which the satellites—usually actively managed vehicles—“revolve.” The rationale behind this is that the core of the portfolio should be consistent with investors’ long-term aims, enabling them to catch asset class risk premiums in efficient markets in a controlled and cost-effective way. The satellites are meant to generate alpha in inefficient market segments.

The crystal structure of bis(NN-diethylethylenediamine)copper(II) dinitrate and the electronic properties of some square planar CuN4 chromophores

The crystal structure of the red isomer of [Cu(deen)2][NO3]2(1)(deen =NN-diethylethylenediamine) has been determined by X-ray diffraction using photographic techniques. The crystals are monoclinic, space goup, P21/n, with a= 9.76 (5), b= 12.81 (5), c= 8.24 (5)A, β= 105.87(8)°, and Z= 2. The centrosymmetric CuN4 chromophore is rhombic coplanar with Cu–N bond distance of 2.081 (5)(tertiary nitrogen) and 2.011 (5)A(primary nitrogen). The conformations of the ethyl substituents effectively block the axial position of the CuN4 chromphore and the nitrate ions exist as free ions in the lattice. The single-crstal electronic and e.s.r. spectra of (1) and of Cs2[Cu(succ)4]·2H2O (2)(succ = succinimido), are reported, correlated with the X-ray crystal structures of the complexes, and suggest the presence of significant in-plane π bonding in (2).