Über den einfluß des hydrostatischen druckes auf die ultrastrukturen von zellen und geweben. VI. Reversibilitätsversuche druckinduzierter schädigungen an membranen und mikrotubuli in Zellen mariner Tiere

Gill epithelia of Modiolus modiolus and Mytilus edulis (Baltic and North Seas), and the skin, pharynx and muscles of Branchiostoma lanceolatum (Pallas) have been investigated at the ultrastructural level, employing hydrostatic pressure, to explore the possibility of structural regeneration following decompression. Restoration of all cell structures seems possible to a certain extent, depending on the degree of disintegration and the time period given after decompression. Structural reorganization after release of pressure begins immediately, but no regenerated organelle is comrable with control species, since structural scars remain. Non-reversible destruction to some systems is apparent near the respective LD₅₀-values of the species.     

Über den Einfluß des hydrostatischen druckes auf die ultrastrukturen von zellen und geweben. I. Untersuchungen am Kiemenepithel marine Muscheln

The effect of high hydrostatic pressure on the ultrastructures of gill tissues of a variety of marine bivalves has been investigated employing a new technique of pressure fixation. The degree of disintegration of some cell organelles is augmented by increasing pressure. Pressure effects on the plasmalemma of the cell surface, with its microvilli and the shaft of the cilia, as well as on the microtubuli of the cilia themselves, can be made visible. At low pressure (400 atm), the plasmalemma forms small vesicular elements. At high pressure (700 atm), large oedematous expansions can be observed. The microtubuli of the cilia disintegrate at 700 atm, so that the cross-section only reveals homogeneous electron-dense material. The results indicate that some cell organelles are sensitive to pressure, and underline the importance of hydrostatie pressure as a physiological-ecological factor in the marine environment.     

Über den Einfluß des hydrostatischen Druckes auf die Ultrastrukturen von Zellen und Geweben. II. Untersuchungen an membransystemen von Kiemenepithelien mariner Muscheln und dem Kiemendarm von Branchiostoma lanceolatum

Employing the technique of pressure fixation, high hydrostatic pressure effects on ultrastructures of membrane systems and cell organelles have been investigated, using as material the gill epithelium of marine bivalves and the pharynx epithelium of Branchiostoma lanceolatum (Pallas). Pressure was increased stepwise between 1 and 800 atm. Pressure sensivity of the tissues varies as a function of their structure and function. The degree of disorganization of cell structures increases with increasing pressure. At 300 to 500 atm, the microvilli tend to form small vsicles, which are connected with each other by thin filaments. Especially the basic vesicles become enlarged to oedematous expansions. A variety of membrane disintegrations can be observed on cell organelles, which are connected by membrane-flow. This supports the thesis of the heterogeneity of membranes. Mitochondria reveal destruction of the cristae to an electron-dense material. Membrane lysis can be demonstrated in the endoplasmic reticulum and the plasmalemma of spezialized pharynx cells of B. lanceolatum. The Golgi-apparatus is the only organelle which remains almost unaffected by hystrostatic pressure. There are probably interactions between pressure sensivity of membrane structures and their enzymatic activities.     

Chemical extractions and predicted free ion activities fail to estimate metal transfer from soil to field land snails

This study investigates the relevance of several soil chemical extractions (calcium chloride, acetic acid, citric acid and a four-step sequential procedure) and predicted free metal ion activities in the soil solution to characterise the transfer of trace metals (Cd, Pb, and Zn) from soil to snail soft tissues over a large smelter-impacted area (Metaleurop Nord, Nord-Pas-de-Calais, France). The study was first performed on six snail species together and then specifically on Cepaea sp. and Oxychilus draparnaudi. When the six species were considered together, the accumulation of metals depended mostly on the species. When significant, total or extractable metal concentrations, or the predicted free ion activities, accounted for less than 7% of the variation of the metal concentrations in the snail tissues. Species-specific analyses showed that extractable concentrations explained approximately 25% of the variation of the metal concentrations in O. draparnaudi, and up to 8% in Cepaea snails. When using total soil concentrations and soil properties as explanatory variables, the models were generally slightly better, explaining up to 42% of the variance. The soil extraction procedures and predicted free ion activities used in this study did not accurately estimate the metal transfer from soil to snails and could not be used in risk assessment.     

Mind the Costs: Rescaling and Multi-Level Environmental Governance in Venice Lagoon

Competences over environmental matters are distributed across agencies at different scales on a national-to-local continuum. This article adopts a transaction costs economics perspective in order to explore the question whether, in the light of a particular problem, the scale at which a certain competence is attributed can be reconsidered. Specifically, it tests whether a presumption of least-cost operation concerning an agency at a given scale can hold. By doing so, it investigates whether the rescaling of certain tasks, aiming at solving a scale-related problem, is likely to produce an increase in costs for day-to-day agency operations as compared to the status quo. The article explores such a perspective for the case of Venice Lagoon. The negative aspects of the present arrangement concerning fishery management and morphological remediation are directly linked to the scale of the agencies involved. The analysis suggests that scales have been chosen correctly, at least from the point of view of the costs incurred to the agencies involved. Consequently, a rescaling of those agencies does not represent a viable option.     

Responses of wild small mammals to a pollution gradient: Host factors influence metal and metallothionein levels

We investigated how host factors (species, age, gender) modulated Cd, Pb, Zn, and Cu concentrations, metallothionein levels (MTs) and their relationships in 7 sympatric small mammal species along a pollution gradient. Cd concentrations in liver and kidneys increased with age in all species. Age effect on other metals and MTs differs among species. Gender did not influence metal and MT levels except in the bank vole. Three patterns linking internal metal concentrations and MTs were observed along the gradient: a low metal accumulation with a (i) high (wood mouse) or (ii) low (bank vole) level of MTs accompanied by a slight or no increase of MTs with Cd accumulation; (iii) an elevated metal accumulation with a sharp increase of MTs (common and pygmy shrews). In risk assessment and biomonitoring perspectives, we conclude that measurements of MTs and metals might be associated because they cannot be interpreted properly when considered separately.     

Batch reactor kinetic studies on the reductive dechlorination of chlorinated ethylenes by tetrakis-(4-sulfonatophenyl)porphyrin cobalt

Tetrakis-(4-sulfonatophenyl)porphyrin cobalt was identified as a highly-active reductive dechlorination catalyst for chlorinated ethylenes. Through batch reactor kinetic studies, degradation of chlorinated ethylenes proceeded in a step-wise fashion with the sequential replacement of Cl by H. For perchloroethylene (PCE) and trichloroethylene (TCE), the dechlorination products were quantified and the C₂ mass was accounted for. Degradation of the chlorinated ethylenes was found to be first-order in substrate. Dechlorination trials with increasing catalyst concentration showed a linearly increasing pseudo first-order rate constant which yielded rate laws for PCE and TCE degradation that are first-order in catalyst. The dechlorination activity of this catalyst was compared to that of another water-soluble cobalt porphyrin under the same reaction conditions and found to be comparable for PCE and TCE.     

Integrated and adaptive water resources management: exploring public participation in the UK

Regional Environmental Change - Contemporary water management practices worldwide are informed by two leading paradigms: integrated water resources management and adaptive management. While...