Biochemical effects of cadmium, salinity and temperature on the catabolism of proteins and purines in oreochromis mossambicus (Peters)

In the present investigation, three important stressors: cadmium ion (Cd++), salinity and temperature were selected to study their effects on protein and purine catabolism of O. mossambicus. Cadmium (Cd) is a biologically nonessential metal that can be toxic to aquatic animals. Cadmium is a trace element which is a common constituent of industrial effluents. It is a non-nutrient metal and toxic to fish even at low concentrations. Cadmium ions accumulate in sensitive organs like gills, liver, and kidney of fish in an unregulated manner . Thus; the toxic effects of cadmium are related to changes in natural physiological and biochemical processes in organism. The mechanics of osmoregulation (i.e. total solute and water regulation) are reasonably well understood (Evans, 1984, 1993), and most researchers agree that salinities that differ from the internal osmotic concentration of the fish must impose energetic regulatory costs for active ion transport. There is limited information on protein and purine catabolism of euryhaline fish during salinity adaptation. Within a range of non-lethal temperatures, fishes are generally able to cope with gradual temperature changes that are common in natural systems. However, rapid increases or decreases in ambient temperature may result in sub lethal physiological and behavioral responses. The catabolic pathways of proteins and purines are important biochemical processes. The results obtained signifies that O. mossambicus when exposed to different levels of cadmium ion, salinity and temperature show great variation in the catabolism of proteins and purines. The organism is trying to attain homeostasis in the presence of stressors by increasing or decreasing the activity of certain enzymes. The present study revealed that the protein and purine catabolism in O. mossambicus is sensitive to environmental stressors.

Ein Beitrag zur Modellierung und Simulation von elektromechanischen Systemen

Die in dieser Arbeit durchgeführten Untersuchungen zeigen, daß es möglich ist, komplexe thermische Systeme, unter Verwendung der thermisch-, elektrischen Analogien, mit PSpice zu simulieren. Im Mittelpunkt der Untersuchungen standen hierbei Strangkühlkörper zur Kühlung von elektronischen Bauelementen. Es konnte gezeigt werden,daß alle Wärmeübertragungsarten, (Wärmeleitung, Konvektion und Wärmestrahlung) in der Simulation berücksichtigt werden können. Für die Berechnung der Konvektion wurden verschiedene Methoden hergeleitet. Diese gelten zum einen für verschiedene Kühlkörpergeometrien, wie z.B. ebene Flächen und Kühlrippenzwischenräume, andererseits unterscheiden sie sich, je nachdem, ob freie oder erzwungene Konvektion betrachtet wird. Für die Wärmestrahlung zwischen den Kühlrippen wurden verschiedenen Berechnungsmethoden entwickelt. Für die Simulation mit PSpice wurde die Berechnung der Wärmestrahlung zwischen den Kühlrippen vereinfacht. Es konnte gezeigt werden, daß die Fehler, die durch die Vereinfachung entstehen, vernachlässigbar klein sind. Für das thermische Verhalten einer zu kühlenden Wärmequelle wurde ein allgemeines Modell entworfen. Zur Bestimmung der Modellparameter wurden verschiedene Meßverfahren entwickelt. Für eine im Fachgebiet Elektromechanik entwickelte Wärmequelle zum Test von Kühlvorrichtungen wurde mit Hilfe dieser Meßverfahren eine Parameterbestimmung durchgeführt. Die Erstellung des thermischen Modells eines Kühlkörpers für die Simulation in PSpice erfordert die Analyse der Kühlkörpergeometrie. Damit diese Analyse weitestgehend automatisiert werden kann, wurden verschiedene Algorithmen unter Matlab entwickelt. Es wurde ein Algorithmus entwickelt, der es ermöglicht, den Kühlkörper in Elementarzellen zu zerlegen, die für die Erstellung des Simulationsmodells benötigt werden. Desweiteren ist es für die Simulation notwendig zu wissen, welche der Elementarzellen am Rand des Kühlkörpers liegen, welche der Elementarzellen an einem Kühlrippenzwischenraum liegen und welche Kühlkörperkanten schräg verlaufen. Auch zur Lösung dieser Aufgaben wurden verschiedene Algorithmen entwickelt. Diese Algorithmen wurden zu einem Programm zusammengefaßt, das es gestattet, unterschiedliche Strangkühlkörper zu simulieren und die Simulationsergebnisse in Form der Temperaturverteilung auf der Montagefläche des Kühlkörpers grafisch darzustellen. Es können stationäre und transiente Simulationen durchgeführt werden. Desweiteren kann der thermische Widerstand des Kühlkörpers RthK als Funktion der Verlustleistung der Wärmequelle dargestellt werden. Zur Verifikation der Simulationsergebnisse wurden Temperaturmessungen an Kühlkörpern durchgeführt und mit den Simulationsergebnissen verglichen. Diese Vergleiche zeigen, daß die Abweichungen im Bereich der Streuung der Temperaturmessung liegen. Das hier entwickelte Verfahren zur thermischen Simulation von Strangkühlkörpern kann somit als gut bewertet werden.

Autoridad y legitimación

Este artículo se cuestiona sobre la posibilidad de fundamentación moral de las obligaciones políticas y de la legitimidad de la autoridad, dando una respuesta negativa. Así, se postula que no hay un deber moral de obediencia a la autoridad (política) a la vez que se propone, a partir de allí, una somera defensa del Estado de bienestar.

An assessment of the fine sediment dynamics in an upland river system: INCA-Sed modifications and implications for fisheries

There is a need for better links between hydrology and ecology, specifically between landscapes and riverscapes to understand how processes and factors controlling the transport and storage of environmental pollution have affected or will affect the freshwater biota. Here we show how the INCA modelling framework, specifically INCA-Sed (the Integrated Catchments model for Sediments) can be used to link sediment delivery from the landscape to sediment changes in-stream. INCA-Sed is a dynamic, process-based, daily time step model. The first complete description of the equations used in the INCA-Sed software (version 1.9.11) is presented. This is followed by an application of INCA-Sed made to the River Lugg (1077 km2) in Wales. Excess suspended sediment can negatively affect salmonid health. The Lugg has a large and potentially threatened population of both Atlantic salmon (Salmo salar) and Brown Trout (Salmo trutta). With the exception of the extreme sediment transport processes, the model satisfactorily simulated both the hydrology and the sediment dynamics in the catchment. Model results indicate that diffuse soil loss is the most important sediment generation process in the catchment. In the River Lugg, the mean annual Guideline Standard for suspended sediment concentration, proposed by UKTAG, of 25 mg l− 1 is only slightly exceeded during the simulation period (1995–2000), indicating only minimal effect on the Atlantic salmon population. However, the daily time step simulation of INCA-Sed also allows the investigation of the critical spawning period. It shows that the sediment may have a significant negative effect on the fish population in years with high sediment runoff. It is proposed that the fine settled particles probably do not affect the salmonid egg incubation process, though suspended particles may damage the gills of fish and make the area unfavourable for spawning if the conditions do not improve.

Light and scanning electron microscopy of Henneguya arapaima n. sp (Myxozoa: Myxobolidae) and histology of infected sites in pirarucu (Arapaima gigas: Pisces: Arapaimidae) from the Araguaia River, Brazil

In this report, we describe Henneguya arapaima n. sp., a parasite of the gill arch and gall bladder of Arapaima gigas (pirarucu) collected in the Araguaia River, in the municipality of Nova Crixas, Goias State, central Brazil. The plasmodia were white, round or ellipsoidal and measured 200-600 mu m. Parasite development was asynchronous and the mature spores were fusifonn and had smooth wall. The spores measurements were (range, with means +/- S.D. in parentheses): total length-48.4-53.1 mu m (51.6 +/- 3.4 mu m), body length-13.5-15.2 mu m (14.2 +/- 0.8 mu m), body width-5.1-6.1 mu m (5.7 +/- 0.5 mu m), body thickness-4.7-5.3 mu m (4.9 +/- 0.2 mu m) and caudal process length-38.0-41.2 mu m (38.3 +/- 2.9 mu m). The polar capsules were elongated and of unequal size, with lengths of 6.3-6.8 mu m (6.5 +/- 0.2) and 6.2-6.6 mu m (6.3 +/- 0.1) for the longest and shortest axes, respectively. Capsule width was 1.4-1.6 mu m (1.5 +/- 0.1). Histological analysis showed that the plasmodia occurred in the tunica adventitia of the gall bladder and were delimited by a thin capsule of connective tissue. In the gill arch, the plasmodia were also surrounded by connective tissue similar to the endomesium, of striated skeletal muscle cells. Sixty-five juvenile specimens of A. gigas weighing 1.0-25.0 kg were examined, 17 (26.1%) of which were infected. Of these, 14 (82.3%) had cysts in the gall bladder, two (11.7%) had cysts in the gill arch and only one (5.9%) had cysts in both organs. When the fish were grouped by weight, the prevalence of infection in fish weighing up to 10.0 kg (20.7%) was significantly lower than in fish weighing 10.1-25.0 kg (50%) (G = 3.93; d.f. = 1; p < 0.05). (C) 2008 Elsevier B.V. All rights reserved.

Separation and viability of gill and hepatopancreatic cells of a mangrove crab Ucides cordatus

The gills contain essential cells for respiration and osmoregulation, whereas the hepatopancreas is the site of digestion, absorption, and nutrients storage. The aim of this work was to separate and characterize gill and hepatopancreatic cells of the mangrove crab, Ucides cordatus. For gills, the methodology consisted of an enzymatic cellular dissociation using Trypsin at 0.5%, observation of cellular viability with Tripan Blue, and separation of cells using discontinuous sucrose gradient at concentrations of 10%, 20%, 30%, and 40%. The hepatopancreatic cells were dissociated by magnetic stirring, with posterior separation by sucrose gradient at the same concentrations above. For gills, a high cellular viability was observed (92.5 +/- 2.1%), with hemocyte cells in 10% sucrose layer (57.99 +/- 0.17%, *P < 0.05), principal cells in the 20% sucrose layer (57.33 +/- 0.18, *P < 0.05), and thick cells and pillar cells in the 30% and 40% sucrose layers, respectively (39.54 +/- 0.05%, *P < 0.05; and 41.81 +/- 0.04%, *P < 0.05). The hepatopancreatic cells also showed good viability (79.22 +/- 0.02%), with the observation of embryonic (E) cells in the 10% sucrose layer (67.87 +/- 0.06%, **P < 0.001), resorptive (R) and fibrillar (F) cells in the 20% and 30% sucrose layers (44.71 +/- 0.06%, **P < 0.001, and 43.25 +/- 0.01%, *P < 0.05; respectively), and blister (B) cells in the 40% sucrose layer (63.09 +/- 0.03%, **P < 0.001). The results are a starting point for in vitro studies of heavy metal transport in isolated cells of the mangrove crab U. cordatus, subjected to contamination by metals in the mangrove habitat where they are found.

Dietary copper absorption and excretion in three semi-terrestrial grapsoid crabs with different levels of terrestrial adaptation

Three species of phylogenetically related semi-terrestrial crabs (Superfamily Grapsoidea - Sesarma rectum, Goniopsis cruentata and Neohelice granulata (formerly: Chasmagnathus granulatus) with different degrees of terrestriality were studied to quantify the accumulation of copper (Cu) in hemolymph, gills, hepatopancreas and antennal gland, and its excretion through the faeces. These crabs were fed for 15 days practical diets containing 0 (A), 0.5 (B), 1.0 (C), and 1.5% (D) of added CuCl2 (corresponding to 0, 0.2, 0.5 and 0.7% of Cu2+, respectively). The amount of food ingested was directly proportional to the degree of terrestriality: S. rectum, the most terrestrial species, ate around 2-3 times more than the other crabs, whereas G. cruentata ate 1.5-2 times more than N. granulata, the least terrestrial. The amount of Cu excreted in the feces was proportional to Cu ingestion, and was 76.8% and 64.2% higher for Sesarma fed diet D compared to G. cruentata and N. granulata, respectively. Sesarma also displayed higher Cu concentration in the haemolymph, gills and antennal glands, but not in the hepatopancreas. A detoxifying mechanism followed by elimination was probably present at this last organ, preventing Cu accumulation. More terrestrial crabs, such as Sesarma, may accumulate more Cu in hemolymph and tissues, showing a correlation between metal accumulation and increased terrestriality. In this aspect, contaminated feed sources with Cu may have more impact in conservation of terrestrial crabs. (C) 2008 Elsevier Inc. All rights reserved.

(65)Zn(2+) transport by isolated gill epithelial cells of the American lobster, Homarus americanus

Gills are the first site of impact by metal ions in contaminated waters. Work on whole gill cells and metal uptake has not been reported before in crustaceans. In this study, gill filaments of the American lobster, Homarus americanus, were dissociated in physiological saline and separated into several cell types on a 30, 40, 50, and 80% sucrose gradient. Cells from each sucrose solution were separately resuspended in physiological saline and incubated in (65)Zn(2+) in order to assess the nature of metal uptake by each cell type. Characteristics of zinc accumulation by each kind of cell were investigated in the presence and absence of 10 mM calcium, variable NaCl concentrations and pH values, and 100 mu M verapamil, nifedipine, and the calcium ionophore A23187. (65)Zn(2+) influxes were hyperbolic functions of zinc concentration (1-1,000 mu M) and followed Michaelis-Menten kinetics. Calcium reduced both apparent zinc binding affinity (K (m)) and maximal transport velocity (J (max)) for 30% sucrose cells, but doubled the apparent maximal transport velocity for 80% sucrose cells. Results suggest that calcium, sodium, and protons enter gill epithelial cells by an endogenous broad-specificity cation channel and trans-stimulate metal uptake by a plasma membrane carrier system. Differences in zinc transport observed between gill epithelial cell types appear related to apparent affinity differences of the transporters in each kind of cell. Low affinity cells from 30% sucrose were inhibited by calcium, while high affinity cells from 80% sucrose were stimulated. (65)Zn(2+) transport was also studied by isolated, intact, gill filament tips. These intact gill fragments generally displayed the same transport properties as did cells from 80% sucrose and provided support for metal uptake processes being an apical phenomenon. A working model for zinc transport by lobster gill cells is presented.

The combined effect of copper and low pH on antioxidant defenses and biochemical parameters in neotropical fish pacu, Piaractus mesopotamicus (Holmberg, 1887)

Copper sulfate is widely used in aquaculture. Exposure to this compound can be harmful to fish, resulting in oxidative metabolism alterations and gill tissue damage. Pacu, Piaractus mesopotamicus, (wt = 43.4 +/- A 3.35 g) were distributed in experimental tanks (n = 10; 180 l) and exposed for 48 h to control (without copper addition), 0.4Cu (0.4 mg l(-1)), 0CupH (without copper addition, pH = 5.0) and 0.4CupH (0.4 mg l(-1), pH = 5.0). In liver and red muscle, the superoxide dismutase (SOD) was responsive to the increases in the aquatic copper. The plasmatic intermediary metabolites and hematological variables in the fish of group 0.4Cu were similar to those of the control group. Conversely, the exposure to 0.4CupH caused an increase in the plasmatic lactate, number of red blood cells (RBC) and hemoglobin (Hb). Plasmatic copper concentration [Cu(p)] increased in group 0.4Cu and 0.4CupH, which is higher in group 0.4CupH, suggests an effect of water pH on the absorbed copper. Exposure to 0.4Cu and 0.4CupH resulted in a reduction in the Na(+)/K(+)-ATPase activity and an increase in metallothionein (MT) in the gills. Exposure to 0CupH caused a decrease in glucose and pyruvate concentrations and an increase in RBC, Hb, and the branchial Na(+)/K(+)-ATPase activity. These responses suggest that the fish triggered mechanisms to revert the blood acidosis, save energy and increase the oxygen uptake. MT was an effective biomarker, responding to copper in different pHs and dissolved oxygen. Combined-factors caused more significant disturbance in the biomarkers than single-factors.

Salinity influences glutathione S-transferase activity and lipid peroxidation responses in the Crassostrea gigas oyster exposed to diesel oil

Biochemical responses in bivalve mollusks are commonly employed in environmental studies as biomarkers of aquatic contamination. The present study evaluated the possible influence of salinity (35, 25,15 and 9 ppt) in the biomarker responses of Crassostrea gigas oysters exposed to diesel at different nominal concentrations (0.01, 0.1 and 1 mLL(-1)) using a semi-static exposure system. Salinity alone did not resulted in major changes in the gill`s catalase activity (CAT), glutathione S-transferase activity (GST) and lipid peroxidation levels (measured as malondialdehyde. MDA), but influenced diesel related responses. At 25 ppt salinity, but not at the other salinity levels, oysters exposed to diesel showed a strikingly positive concentration-dependent GST response. At 25 ppt and 1 mLL(-1) diesel, the GST activity in the gills remained elevated, even after one week of depuration in clean water. The increased MDA levels in the oysters exposed to diesel comparing to control groups at 9, 15 and 35 ppt salinities suggest the occurrence of lipid peroxidation in those salinities, but not at 25 ppt salinity. The MDA quickly returned to basal levels after 24 h of depuration. CAT activity was unaltered by the treatments employed. High toxicity for 1 mLL(-1) diesel was observed only at 35 ppt salinity, but not in the other salinities. Results from this study strongly suggest that salinity influences the diesel related biomarker responses and toxicity in C. gigas, and that some of those responses remain altered even after depuration. (C) 2011 Elsevier B.V. All rights reserved.

Guanylyl cyclase stimulation by homologous and heterologous natriuretic peptides in salmonids

A range of homologous (trout ANP, trout CNP, trout VNP) and heterologous (eel ANP, eel ANP-NH₂, rat ANP, porcine CNP) NPs were tested for their effect on guanylyl cyclase in gill and kidney membrane preparations from freshwater and seawater-acclimated rainbow trout and Atlantic salmon. All NPs stimulated guanylyl cyclase at 1 µmol l^-1in all preparations. ANP was the most potent stimulator of kidney guanylyl cyclase and CNP the most potent stimulator of guanylyl cyclase in gills. Some differences were apparent between the potencies of homologous and heterologous peptides at 1 µmol l^-1: tANP was more potent than rANP in the SW trout kidney and tCNP was more potent than pCNP in FW salmon tissues. While eANP was more potent than tANP in trout gills, it was less potent than tANP in FW salmon gills. However, there was no significant difference between the potencies of eANP and eANP-NH₂ in trout or salmon gills. Salinity did not affect guanylyl cyclase activity with the exception that trout ANP at 1 µmol l^-1was more potent in SW trout kidneys than in FW trout kidneys. These results suggest a predomination of NPR-A in the kidney and NPR-B in the gill. It appears that salmonid NPR-A and NPR-B are relatively promiscuous in their ligand affinity, with few differences in the potencies of trout and mammalian NPs and only small differences in cGMP production where these differences do occur.

Comparative aspects of natriuretic peptide physiology in non-mammalian vertebrates: a review

The natriuretic peptide system is a complex family of peptides and receptors that is primarily linked to the maintenance of osmotic and cardiovascular homeostasis. A natriuretic peptide system is present in each vertebrate class but there are varying degrees of complexity in the system. In agnathans and chondrichthyians, only one natriuretic peptide has been identified, while new data has revealed that multiple types of natriuretic peptides are present in bony fish. However, it seems in tetrapods that there has been a reduction in the number of natriuretic peptide genes, such that only three natriuretic peptides are present in mammals. The peptides act via a family of guanylyl cyclase receptors to generate the second messenger cGMP, which  mediates a range of physiological effects at key targets such as the gills, kidney and the cardiovascular system. This review summarises the current knowledge of the natriuretic peptide system in non-mammalian vertebrates and discusses the physiological actions of the peptides.

Osmoregulatory balance in Murray cod, Maccullochella peelii peelii (Mitchell), affected with chronic ulcerative dermatopathy

This study examined the osmoregulatory capability of Murray cod, Maccullochella peelii peelii, affected by chronic ulcerative dermatopathy (CUD) in intensive aquaculture. This condition appears to arise only in facilities utilizing groundwater, with the causative agent suggested to be a water-borne factor. Healthy Murray cod (~ 700 g) were transferred to a CUD-affected farm to monitor the progression of the syndrome and began to show signs of CUD after approximately five months. In order to evaluate possible effects of CUD on osmoregulation; plasma electrolyte concentrations, osmolality, and Na⁺,K⁺-ATPase activities were measured, and gill histology and immunohistochemistry were analyzed. Plasma electrolyte concentrations and osmolality of CUD-affected Murray cod were consistent with reference values determined for non CUD-affected fish. A greater number of gill mucous cells were observed in Murray cod cultured at the CUD-affected farm compared to non CUD-affected fish. We also found an un-identified cell type that was present solely in the gills of CUD-affected Murray cod. Gill Na⁺,K⁺-ATPase activity was significantly higher in severely CUD-affected Murray cod compared to individuals transferred to the CUD-affected farm. While there appeared to be some minor changes in the gills of CUD-affected fish, this study demonstrated that Murray cod were able to effectively osmoregulate, although, perhaps at an energetic cost.

Using omeprazole to link the components of the post-prandial alkaline tide in the spiny dogfish, Squalus acanthias

After a meal, dogfish exhibit a metabolic alkalosis in the bloodstream and a marked excretion of basic equivalents across the gills to the external seawater. We used the H⁺, K⁺-ATPase pump inhibitor omeprazole to determine whether these post-prandial alkaline tide events were linked to secretion of H⁺ (accompanied by Cl^–) in the stomach. Sharks were fitted with indwelling stomach tubes for pretreatment with omeprazole (five doses of 5mg omeprazole per kilogram over 48 h) or comparable volumes of vehicle (saline containing 2% DMSO) and for sampling of gastric chyme. Fish were then fed an involuntary meal by means of the stomach tube consisting of minced flatfish muscle (2% of body mass) suspended in saline (4% of body mass total volume). Omeprazole pretreatment delayed the post-prandial acidification of the gastric chyme, slowed the rise in Cl^– concentration of the chyme and altered the patterns of other ions, indicating inhibition of H⁺ and accompanying Cl^– secretion. Omeprazole also greatly attenuated the rise in arterial pH and bicarbonate concentrations and reduced the net excretion of basic equivalents to the water by 56% over 48h. Arterial blood CO₂ pressure and plasma ions were not substantially altered. These results indicate that elevated gastric H⁺ secretion (as HCl) in the digestive process is the major cause of the systemic metabolic alkalosis and the accompanying rise in base excretion across the gills that constitute the alkaline tide in the dogfish.

Histological alterations in the Antarctic cod, Trematomus bernacchii from Davis Station, East Antarctica

During the summer season 2009/10, a comprehensive environmental impact assessment of the sewage discharge was conducted at Davis Station in the Vestfold Hills region of East Antarctica. As part of this project, a survey of the histology of liver, gill, gonad and muscle tissues in the Antarctic rock cod Trematomus bernacchii from nearshore sites in the receiving environment close to Davis Station in was completed. Fish from 4 sites were examined; 1 site adjacent to the Davis Station sewage outfall (within 500 m of the point of discharge), 2 sites approximately 2 km from the outfall (Anchorage Island and Antennae farm), and 1 site approximately 10 km away from the outfall and adjacent to an Adelie penguin population (Kazak Island). All fish sampled from the sewage outfall site exhibited significant histological alterations in all major tissues. Fish from the other 3 sites showed some alterations in either gill and/or liver tissues. Pathological abnormalities present in all fish collected near the sewage outfall included: extensive multifocal cysts of unknown etiology with necrotic liquification; multifocal granuloma with associated inflammation; coagulative necrosis in the liver; and lamellar hyperplasia with associated proliferation and lamella fusion of the gills. Results of this work form part of a weight of evidence approach alongside ecological monitoring, chemical analysis, ecotoxicological testing and dispersal modelling of the discharge plume which is being used to inform and direct upgrades to the Australian Antarctic Divisions operations and current sewage discharge practises at Davis Station.