Ecological and Behavioural Correlates of Intracellular Buffering Capacity in the Muscles of Antarctic Fishes

Five species of antarctic fishes can be arranged in order of increasing anaerobic capacity of the white muscles for burst swimming: Rhigophila dearborni (Zoarcidae), icefish (Channichthyidae), Dissostichus mawsoni, Trematomus centronotus, and Pagothenia borchgrevinki (Nototheniidae). This order reflects in-creasing dependence on anaerobic work done during short bursts of speed during prey capture or predator avoidance. Buffer capacity (beta) for white muscle was lower than that of behaviourally equivalent fish from lower latitudes and beta is itself temperature-dependent

Are attitudes towards mental health help-seeking associated with service use? Results from the European Study of Epidemiology of Mental Disorders

To investigate the prevailing attitudes towards mental health help-seeking in Europe, their correlates, and whether these attitudes are associated with actual service use for mental health problems. Data were derived from the European Study of Epidemiology of Mental Disorders, a survey representative of the adult population of six countries: Belgium, France, Germany, Italy, the Netherlands and Spain (n = 8,796). The World Mental Health Composite International Diagnostic Interview was used to assess attitudes and DSM-IV diagnoses. The attitudes referred to beliefs that the respondents would seek professional help when faced with a serious emotional problem, would feel comfortable talking about personal problems with a professional, would not be embarrassed if friends knew about the professional help, and respondents' perceived effectiveness of mental health care. Almost a third of the respondents held the view that professional care was worse than or equal to no help when faced with serious emotional problems. Female gender, being younger than 65 years of age, high income, living in Spain or Italy, presence of mood disorder and previous service use were associated with at least two of the four assessed attitudes towards mental health help-seeking. All four attitudes were significantly associated with mental health care use, also after adjustment for previous service use. The low perceived effectiveness of professional care calls for serious action aiming to improve the visibility and credibility of the mental health care sector

Oxygen limited thermal tolerance in Antarctic fish investigated by MRI and 31P-MRS

The hypothesis of an oxygen limited thermal tolerance was tested in the Antarctic teleost Pachycara brachycephalum. Using flow-through respirometry, in vivo 31P-NMR spectroscopy and MRI, we studied energy metabolism, intracellular pH (pHi), blood-flow and oxygenation between 0 and 13°C under normoxia (PO2: 20,3 to 21,3kPa) and hyperoxia (PO2: 45kPa). Hyperoxia reduced the metabolic increment and the rise in arterial blood-flow observed under normoxia. The normoxic increase of blood-flow levelled off beyond 7°C, indicating a cardiovascular capacity limitation. Ventilatory effort displayed an exponential rise in both groups. In the liver, blood oxygenation increased, whereas in white muscle it remained unaltered (normoxia) or declined (hyperoxia). In both groups, the slope of pHi changes followed the alpha-stat pattern below 6°C, whereas it decreased above. In conclusion, aerobic scope declines around 6°C under normoxia, marking the pejus temperature Tp. By reducing circulatory costs, hyperoxia improves aerobic scope but is unable to shift the breakpoint in pH regulation or lethal limits. Hyperoxia appears beneficial at sublethal temperatures, but no longer beyond when cellular or molecular functions become disturbed

Characterization of the hemoglobins of the Australian lungfish Neoceratodus forsteri (Krefft)

Copyright © 2008 ElsevierWe examined for the first time the hemoglobin components of the blood of the Australian lungfish, Neoceratodus forsteri and their functional responses to pH and the allosteric modulators adenosine triphosphate (ATP), guanosine triphosphate (GTP), 2,3-bisphosphoglyceric acid (BPG) and inositol hexaphosphate (IHP) at 25 °C. Lysates prepared from stripped, unfractionated hemolysate produced sigmoidal oxygen equilibrium curves with high oxygen affinity (oxygen partial pressure required for 50% hemoglobin saturation, p50 = 5.3 mmHg) and a Hill coefficient of 1.9 at pH 7.5. p50 was 8.3 and 4.5 mmHg at pH 6 and 8, respectively, which corresponded to a modest Bohr coefficient (Δlog p50/ΔpH) of − 0.13. GTP increased the pH sensitivity of oxygen binding more than ATP, such that the Bohr coefficient was − 0.77 in the presence of 2 mmol L− 1 GTP. GTP was the most potent regulator of hemoglobin affinity, with concentrations of 5 mmol L− 1 causing an increase in p50 from 5 to 19 mm Hg at pH 7.5, while the order of potency of the other phosphates was IHP > ATP > BPG. Three hemoglobin isoforms were present and each contained both α and β chains with distinct molecular weights. Oxygen affinity and pH-dependence of isoforms I and II were essentially identical, while isoform III had a lower affinity and increased pH-dependence. The functional properties of the hemoglobin system of Neoceratodus appeared consistent with an active aquatic breather adapted for periodic hypoxic episodes.Jonas R. Rasmussen, Rufus M.G. Wells, Kristen Henty, Timothy D. Clark and Thomas Brittainhttp://www.sciencedirect.com/science/journal/1095643