Modelling interactions of acid–base balance and respiratory status in the toxicity of metal mixtures in the American oyster Crassostrea virginica

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology 155 (2010): 341-349, doi:10.1016/j.cbpa.2009.11.019.Heavy metals, such as copper, zinc and cadmium, represent some of the most common and serious pollutants in coastal estuaries. In the present study, we used a combination of linear and artificial neural network (ANN) modelling to detect and explore interactions among low-dose mixtures of these heavy metals and their impacts on fundamental physiological processes in tissues of the Eastern oyster, Crassostrea virginica. Animals were exposed to Cd (0.001 – 0.400 μM), Zn (0.001 – 3.059 μM) or Cu (0.002 – 0.787 μM), either alone or in combination for 1 to 27 days. We measured indicators of acid-base balance (hemolymph pH and total CO2), gas exchange (Po2), immunocompetence (total hemocyte counts, numbers of invasive bacteria), antioxidant status (glutathione, GSH), oxidative damage (lipid peroxidation; LPx), and metal accumulation in the gill and the hepatopancreas. Linear analysis showed that oxidative membrane damage from tissue accumulation of environmental metals was correlated with impaired acid-base balance in oysters. ANN analysis revealed interactions of metals with hemolymph acid-base chemistry in predicting oxidative damage that were not evident from linear analyses. These results highlight the usefulness of machine learning approaches, such as ANNs, for improving our ability to recognize and understand the effects of sub-acute exposure to contaminant mixtures.This study was supported by NOAA’s Center of Excellence in Oceans and Human Health at HML and the National Science Foundation

The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)

Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species—drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations

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Synthesis of α-Al2O3 thin films using reactive high power impulse magnetron sputtering

α-alumina coatings have been deposited directly onto cemented-carbide and Mo substrates at a temperature as low as 650 °C using reactive high-power impulse magnetron sputtering (HiPIMS) of Al in an Ar/O2 gas mixture. The coatings consisted of plate-like crystallites, as revealed by scanning electron microscopy. α phase growth was retained over the studied range of substrate bias voltages (from floating potential up to -100 V), with films exhibiting a slightly denser microstructure at higher bias voltages. X-ray diffraction indicated that the α-alumina grains had a preferred orientation of (0001)-planes perpendicular to the substrate surface. X-ray analysis of films deposited at 575 °C indicated the presence of γ-alumina, whereas films grown at 500 °C or lower were X-ray amorphous.Original Publication:Erik Wallin, T. I. Selinder, M. Elfwing and Ulf Helmersson, Synthesis of α-Al2O3 thin films using reactive high power impulse magnetron sputtering, 2008, Europhysics letters, (82), 36002.http://dx.doi.org/10.1209/0295-5075/82/36002Copyright: EDP Sciences.http://publications.edpsciences.org

Coronary blood flow in the anesthetized American alligator (Alligator mississippiensis)

Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American alligators (Alligator mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressur

J. Chromatogr. A

The goal of this study was to investigate the applicability of asymmetrical flow field-flow fractionation-multi-angle light scattering (AsFIFFFMALS) for size analysis of green fluorescent protein inclusion bodies (GFPIBs). The size distributions of GFPIBs prepared by various culture conditions were determined. For GFPIBs prepared at 37 degrees C the peak maximum hydrodynamic diameter (dH) first increased and then decreased with the increase of the induction times in the presence of 0.1 and 2 mM isopropyl-beta-D-thiogalactoside (IPTG). For GFPIBs prepared at 30 degrees C the peak maximum dH was constant at about 700 nm irrespectively of the induction times and IPTG concentrations. (c) 2005 Elsevier B.V. All rights reserved.The goal of this study was to investigate the applicability of asymmetrical flow field-flow fractionation-multi-angle light scattering (AsFIFFFMALS) for size analysis of green fluorescent protein inclusion bodies (GFPIBs). The size distributions of GFPIBs prepared by various culture conditions were determined. For GFPIBs prepared at 37 degrees C the peak maximum hydrodynamic diameter (dH) first increased and then decreased with the increase of the induction times in the presence of 0.1 and 2 mM isopropyl-beta-D-thiogalactoside (IPTG). For GFPIBs prepared at 30 degrees C the peak maximum dH was constant at about 700 nm irrespectively of the induction times and IPTG concentrations. (c) 2005 Elsevier B.V. All rights reserved