Characterisation and expression of β1-, β2- and β3-adrenergic receptors in the fathead minnow (Pimephales promelas)

This is the author’s version of a work that was accepted for publication in General and Comparative Endocrinology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published and may be accessed at the link below. Copyright © 2011 Elsevier B.V. All rights reserved.Complimentary DNAs for three beta-adrenergic receptors (βARs) were isolated and characterised in the fathead minnow. The encoded proteins of 402 (β(1)AR), 397 (β(2)AR) and 434 (β(3)AR) amino acids were homologous to other vertebrate βARs, and displayed the characteristic seven transmembrane helices of G Protein-coupled receptors. Motifs and amino acids shown to be important for ligand binding were conserved in the fathead minnow receptors. Quantitative RT-PCR revealed the expression of all receptors to be highest in the heart and lowest in the ovary. However, the β(1)AR was the predominant subtype in the heart (70%), and β(3)AR the predominant subtype in the ovary (53%). In the brain, β(1)AR expression was about 200-fold higher than that of β(2)- and β(3)AR, whereas in the liver, β(2)AR expression was about 20-fold and 100-fold higher than β(3)- and β(1)AR expression, respectively. Receptor gene expression was modulated by exposure to propranolol (0.001-1mg/L) for 21days, but not in a consistent, concentration-related manner. These results show that the fathead minnow has a beta-adrenergic receptor repertoire similar to that of mammals, with the molecular signatures required for ligand binding. An exogenous ligand, the beta-blocker propranolol, is able to alter the expression profile of these receptors, although the functional relevance of such changes remains to be determined. Characterisation of the molecular targets for beta-blockers in fish will aid informed environmental risk assessments of these drugs, which are known to be present in the aquatic environment.European Union as part of the ERAPharm project, Contract No. 511135 and NER

Chronic effects assessment and plasma concentrations of the b-blocker propranolol in fathead minnows (Pimephales promelas)

The presence of many human pharmaceuticals in the aquatic environment is now a worldwide concern, yet little is known of the chronic effects that these bioactive substances may be having on aquatic organisms. Propranolol, a non-specific beta adrenoreceptor blocker (beta-blocker), is used to treat high blood pressure and heart disease in humans. Propranolol has been found in surface waters worldwide at concentrations ranging from 12 to 590ng/L. To test the potential for ecologically relevant effects in fish in receiving waters, short-term (21 days) adult reproduction studies were conducted, in which fathead minnows were exposed to nominal concentrations of propranolol hydrochloride [CAS number 318-98-9] ranging from 0.001 to 10mg/L (measured concentrations typically from 78 to 130%). Exposure of fish to 3.4mg/L (measured) over 3 days caused 100% mortality or severe toxicity requiring euthanasia. The most sensitive endpoints from the studies were a decrease in hatchability (with regard to the number of days to hatch) and a concentration-related increase in female gonadal somatic index (GSI), giving LOEC(hatchability) and LOEC(female GSI) values of 0.1mg/L. Concentration-related decreases in weights of male fish were also observed, with LOEC(male wet weight value) of 1.0mg/L, and the LOEC(reproduction) value was 1.0mg/L. Collectively, these data do not suggest that propranolol was acting as a reproductive toxin. Plasma concentrations of propranolol in male fish exposed to nominal concentrations of 0.1 and 1.0mg/L were 0.34 and 15.00mg/L, respectively, which constitutes 436 and 1546% of measured water concentrations. These compare with predicted concentrations of 0.07 and 0.84mg/L, and thus to a degree support the use of partition coefficient models for predicting concentrations in plasma in fish. In addition, propranolol plasma concentrations in fish exposed to water concentrations of 0.1 and 1.0mg/L were greater than the human therapeutic plasma concentration and hence these data very strongly support the fish plasma model proposed by Huggett et al. [Huggett, D.B., Cook, J.C., Ericson, J.F., Williams, R.T., 2003a. A theoretical model for utilizing mammalian pharmacology and safety data to prioritize potential impacts of human pharmaceuticals to fish. Hum. Ecol. Risk Assess. 9, 1789-1799]

The read-across hypothesis and environmental risk assessment of pharmaceuticals

This article is made available through the Brunel Open Access Publishing Fund. Copyright © 2013 American Chemical Society.Pharmaceuticals in the environment have received increased attention over the past decade, as they are ubiquitous in rivers and waterways. Concentrations are in sub-ng to low μg/L, well below acute toxic levels, but there are uncertainties regarding the effects of chronic exposures and there is a need to prioritise which pharmaceuticals may be of concern. The read-across hypothesis stipulates that a drug will have an effect in non-target organisms only if the molecular targets such as receptors and enzymes have been conserved, resulting in a (specific) pharmacological effect only if plasma concentrations are similar to human therapeutic concentrations. If this holds true for different classes of pharmaceuticals, it should be possible to predict the potential environmental impact from information obtained during the drug development process. This paper critically reviews the evidence for read-across, and finds that few studies include plasma concentrations and mode of action based effects. Thus, despite a large number of apparently relevant papers and a general acceptance of the hypothesis, there is an absence of documented evidence. There is a need for large-scale studies to generate robust data for testing the read-across hypothesis and developing predictive models, the only feasible approach to protecting the environment.BBSRC Industrial Partnership Award BB/ I00646X/1 and BBSRC Industrial CASE Partnership Studentship BB/I53257X/1 with AstraZeneca Safety Health and Environment Research Programme

Behavior of quartz forks oscillating in isotopically pure He-4 in the T -> 0 limit

We report that at low drives, the resonant frequencies and linewidths of nominally 32-kHz quartz tuning forks oscillating in isotopically pure superfluid He-4 at similar to 10 mK are dependent on the dimensions of their environment. We confirm the importance of coupling between forks and acoustic modes within the cell, and develop a theory of their coupled dynamics to account for the observations. The frequencies and linewidths are reproducible on a time scale of tens of minutes, but pronounced drifts are seen over longer intervals. We suggest that the drifts are attributable to changes in the velocity of sound due to tiny pressure changes. In studies at high drives, we observe two critical velocities: v(c1) approximate to 0.6 cm/s, where the drag may either increase or decrease, depending on the linewidth; and v(c2) approximate to 10 cm/s, above which there seems to be fully turbulent flow. At high drives, the behavior of the drag differs markedly between forks that appear otherwise to be very similar

Mutual interactions between objects oscillating in isotopically pure superfluid He-4 in the T -> 0 limit

We report the results of experiments to explore interactions between physically separated oscillating objects in isotopically pure superfluid He-4 at T similar to 10 mK. The investigations focused mainly on 32 kHz quartz tuning forks, but also consider a nearby 1 kHz oscillating grid. The low-drive linewidth (LDL) and resonant frequency f(d) of a detector fork were monitored while the maximum velocity of a transmitter fork, separated from the detector by a few mm, was varied over a wide range. Clear evidence was found for mutual interactions between the two forks, and for the influence of the grid on the forks. Monitoring the detector's LDL and f(d) provides evidence for a generator critical velocity in the range 0.3 < nu(c1) < 1.0 cm/s for onset of the detector responses, in addition to a second critical velocity nu(c2) similar to 13 cm/s probably corresponding to the production of quantum turbulence at the generator. The results are discussed, but are not yet fully understood. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4765091

Targeting the environmental risk assessment of pharmaceuticals Facts and fantasies

In contrast to industrial chemicals, pharmaceuticals and pesticides are designed to show specific pharmacological actions or biocidal activities. Despite this difference, the same principles for environmental risk assessment, e.g.;risk characterization by comparing compartment-specific exposure and effect, are applied to both nonspecifically and specifically acting substances. In addition, many pharmaceuticals are relatively hydrophilic, polar, or charged compounds. However, standardized guidelines for generating fate and effects data have been developed predominantly for neutral substances. For these reasons, the risk characterization of biologically active pharmaceuticals might contain a considerable degree of uncertainty. In this paper, we propose a conceptual approach for a targeted environmental risk assessment to reduce the uncertainties of risk characterization for pharmaceuticals by using the information provided in the nonenvironmental part of the regulatory dossier. Three steps have been defined for this purpose 1) The first is collation of specific information contained in regulatory dossiers for pharmaceuticals, e.g.;data produced to understand the interaction of the active substance with biological structures, 2) Based on this information, conclusions might be drawn with regard to environmental compartments likely to be exposed and organisms likely to be affected, and 3) Selection can be made of single-species or multispecies tests to generate additional information for the ecotoxicological risk characterization of pharmaceuticals. Furthermore, some thoughts will be presented on the integration of targeted testing strategies into conceptual regulatory guidance. Integr Environ Assess Manag 2010;6603 613. © 2009 SETAC

Seawater carbonate chemistry and calcification physiology of coralline algae

Crustose coralline algae play a crucial role in the building of reefs in the photic zones of nearshore ecosystems globally, and are highly susceptible to ocean acidification. Nevertheless, the extent to which ecologically important crustose coralline algae can gain tolerance to ocean acidification over multiple generations of exposure is unknown. We show that, while calcification of juvenile crustose coralline algae is initially highly sensitive to ocean acidification, after six generations of exposure the effects of ocean acidification disappear. A reciprocal transplant experiment conducted on the seventh generation, where half of all replicates were interchanged across treatments, confirmed that they had acquired tolerance to low pH and not simply to laboratory conditions. Neither exposure to greater pH variability, nor chemical conditions within the micro-scale calcifying fluid internally, appeared to play a role in fostering this capacity. Our results demonstrate that reef-accreting taxa can gain tolerance to ocean acidification over multiple generations of exposure, suggesting that some of these cosmopolitan species could maintain their critical ecological role in reef formation

Nonlinear second sound waves and acoustic turbulence in superfluid He-4.

The preliminary results of an investigation of nonlinear second sound waves in a high quality resonator filled with superfluid 4He are presented and discussed. It is found that, for a sufficiently strong periodic driving force, a cascade of second sound waves is formed at multiple harmonics of the driving frequency over the extremely wide frequency range 1–100 kHz. It can be described by a power law A ω =const.×ω −m , where the scaling index m≈1. These observation can be attributed to the formation of a Kolmogorov-like turbulent cascade in the system of second sound waves, accompanied by directed energy flux through the frequency scales. It manifests itself as a limiting of the amplitude of a standing wave, a distortion of the shape of the initially harmonic waves, and a reduction of the effective quality factor Q of the resonator