Thermal acclimation to 4 or 10°C imparts minimal benefit on swimming performance in Atlantic cod ( Gadus morhua L.)

Thermal acclimation is frequently cited as a means by which ectothermic animals improve their Darwinian fitness, i.e. the beneficial acclimation hypothesis. As the critical swimming speed (U crit) test is often used as a proxy measure of fitness, we acclimated Atlantic cod (Gadus morhua) to 4 and 10°C and then assessed their U crit swimming performance at their respective acclimation temperatures and during acute temperature reversal. Because phenotypic differences exist between different populations of cod, we undertook these experiments in two different populations, North Sea cod and North East Arctic cod. Acclimation to 4 or 10°C had a minimal effect on swimming performance or U crit, however test temperature did, with all groups having a 10-17% higher U crit at 10°C. The swimming efficiency was significantly lower in all groups at 4°C arguably due to the compression of the muscle fibre recruitment order. This also led to a reduction in the duration of "kick and glide” swimming at 4°C. No significant differences were seen between the two populations in any of the measured parameters, due possibly to the extended acclimation period. Our data indicate that acclimation imparts little benefit on U crit swimming test in Atlantic cod. Further efforts need to identify the functional consequences of the long-term thermal acclimation proces

Taking the ‘Just' Decision: Caseworkers and Their Communities of Interpretation in the Swiss Asylum Office

Decision-making in street-level bureaucracies has often been portrayed as being riddled with a practical dilemma: that of having to juggle between compassion and rigid rule-following. However, drawing on three ethnographic studies of Swiss asylum administration, we argue that often what are from the “outside” perceived as conflicting rationales of decision-making, are not experienced as such by the caseworkers themselves. Rather these different rationales are made to fit. We argue that decision-makers’ “volitional allegiance” with the office plays a crucial role thereby. For the caseworkers we encountered, decision-making is about taking “just decisions”, i.e. decisions that they consider “correct” and “fair”. We suggest that these notions of correctness and fairness are crucially influenced by their affiliations and allegiances with different “communities of interpretation” within the office

P/O ratio of acclimated <i>N. rossii</i>.

<p>Ratio of ADP produced per oxygen consumed (P/O ratio) by complex I & II (CI & CII) in <i>N. rossii</i> acclimated to 1°C, 0.04 kPa CO₂ (control), <i>n</i> = 9; 7°C, 0.04 kPa CO₂ (warm normocapnic), <i>n</i> = 5; 1°C, 0.2 kPa CO₂ (cold hypercapnic), <i>n</i> = 10; and 7°C 0.2 kPa CO₂ (warm hypercapnic), <i>n</i> = 10. Values are given as means ± SEM. * indicate significantly different P/O ratios at the respective assay temperature within an control/acclimation group (ANOVA, <i>P</i><0.05).</p

Fatty acid composition of phospholipids in liver mitochondria from control, warm and hypercapnia-acclimated <i>N. rossii</i> and <i>L. squamifrons.</i>

<p>Treatments: <i>N. rossii c</i>ontrol: 1°C, 0.04 kPa CO₂; warm normocapnic: 7°C, 0.04 kPa CO₂; cold hypercapnic 1°C, 0.2 kPa CO₂; warm hypercapnic: 7°C, 0.2 kPa CO₂. <i>L. squamifrons</i> control: 2°C, 0.04 kPa CO₂, warm normocapnic: 9°C, 0.04 kPa CO₂.</p><p>Units are percentages of total fatty acids within a control/acclimation group of <i>N. rossii</i> and <i>L. squamifrons</i>. <i>N. rossii</i>: control <i>n</i> = 4, warm normocapnic <i>n</i> = 4, cold hypercapnic <i>n</i> = 7, warm hypercapnic <i>n</i> = 8; <i>L. squamifrons</i>: control <i>n</i> = 7, warm normocapnic <i>n</i> = 5. Data are presented as means ± SEM. All significances are highlighted bold.</p>#<p>indicates a significant (ANOVA, <i>P</i><0.05) difference to the <i>N. rossii</i> control group.</p>a<p>indicates a significant (ANOVA, <i>P</i><0.05) difference to <i>L. squamifrons</i> controls.</p>b<p>indicates a significant difference (ANOVA, <i>P</i><0.05) to <i>L. squamifrons</i> acclimated to 9°C, 0.04 kPa CO₂. SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids; n-3: fatty acids with 3 double bonds in the carbon chain; n-6: fatty acids with 6 double bonds in the carbon chain. Unsaturation index % of fatty acids with <i>n</i> double bonds (adopted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068865#pone.0068865-Grim1" target="_blank">[48]</a>).</p

Maximum proton leak capacities (state IV⁺) as a putative fraction of total mitochondrial state III respiration (complex I and II, liver) in <i>N. rossii</i> and <i>L. squamifrons</i>.

<p>Values are given as means ± SEM over all assay temperatures (0, 6, 12°C) of control/acclimated <i>N. rossii</i> (control: 1°C, 0.04 kPa CO₂, <i>n</i> = 9; warm normocapnic: 7°C, 0.04 kPa CO₂, <i>n</i> = 5; cold hypercapnic: 1°C, 0.2 kPa CO₂, <i>n</i> = 10; warm hypercapnic 7°C, 0.2 kPa CO₂, <i>n</i> = 10) and <i>L. squamifrons</i> (control: 2°C, 0.04 kPa CO₂, <i>n</i> = 7; warm normocapnic 9°C, 0.04 kPa CO₂, <i>n</i> = 5).</p>#<p>indicates a significant (ANOVA, <i>P</i><0.05) difference in comparison to the <i>N. rossii</i> control group.</p>a<p>indicates a significant (ANOVA, <i>P</i><0.05) difference in comparison to <i>L. squamifrons</i> control. T = temperature.</p

Plasticity of proton leak capacity (state IV⁺) in relation to complex II (CII) in state III respiration.

<p>Isolated liver mitochondria from <i>N. rossii</i> acclimated to 1°C, 0.04 kPa CO₂ (control), <i>n</i> = 9; 7°C, 0.04 kPa CO₂ (warm normocapnic), <i>n</i> = 5; 1°C, 0.2 kPa CO₂ (cold hypercapnic), <i>n</i> = 10; and 7°C 0.2 kPa CO₂ (warm hypercapnic), <i>n</i> = 10, and in mitochondria from control (2°C, 0.04 kPa CO₂, <i>n</i> = 7) and warm-acclimated (9°C, 0.04 kPa CO₂, <i>n</i> = 5) <i>L. squamifrons</i>. White dots represent values at 0°C, grey at 6°C and black at 12°C acute assay temperatures. Values are given as means ± SEM. * indicates a significant difference of state III respiration (horizontal error bars) or of mitochondrial proton leak capacity (vertical error bars) from the 0°C assay within a control/acclimation group (ANOVA, <i>P</i><0.05). The dotted line represents 20% leak of the given state III respiration.</p

State III respiration rate of liver mitochondria at various assay temperatures of 0, 6, 12°C.

<p>Mitochondria isolated from <i>N. rossii</i> acclimated to 1°C, 0.04 kPa CO₂ (control), <i>n</i> = 9; 7°C, 0.04 kPa CO₂ (warm normocapnic), <i>n</i> = 5; 1°C, 0.2 kPa CO₂ (cold hypercapnic), <i>n</i> = 10; and 7°C 0.2 kPa CO₂ (warm hypercapnic), <i>n</i> = 10. The total state III rate comprises the involement of complex I (CI, grey part of stacked bars) and II (CII, white part of stacked bars). * indicates significantly increased CI or CII state III respiration over the rate at 0°C within a control/acclimation group (ANOVA, <i>P</i><0.05); ^# indicate significant changes in CII state III respiration compared to the control group at the respective assay temperature (ANOVA, <i>P</i><0.05). Values are given as means ± SEM.</p

State III respiration rate (isolated liver mitochondria) assayed at 0, 6, 12°C in <i>L. squamifrons</i>.

<p>State III respiration comprises complex I (CI, grey part of stacked bars) and II (CII, white part of stacked bars) in control (2°C, 0.04 kPa CO₂), <i>n</i> = 7, and warm acclimated (9°C, 0.04 kPa CO₂), <i>n</i> = 5, <i>L. squamifrons</i>. * depicts a significantly elevated CI and CII state III respiration rate in comparison to the respective rate at 0°C in the control/acclimation group. ^# incidates a significantly lower CI and CII rate in comparison to the control group (ANOVA, <i>P</i><0.05) at the respective assay temperature. Values are given as means ± SEM.</p

Wirkstoffe der Nordsee: Struktur, biologische Aktivitaet und Nutzung neuer Wirkstoffe aus wirbellosen Meerestieren der Nordsee und des Nordmeeres nahe Spitzbergen Abschlussbericht

Available from TIB Hannover: F04B187+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Mitochondrial Acclimation Capacities to Ocean Warming and Acidification Are Limited in the Antarctic Nototheniid Fish, Notothenia rossii and Lepidonotothen squamifrons

Antarctic notothenioid fish are characterized by their evolutionary adaptation to the cold, thermostable Southern Ocean, which is associated with unique physiological adaptations to withstand the cold and reduce energetic requirements but also entails limited compensation capacities to environmental change. This study compares the capacities of mitochondrial acclimation to ocean warming and acidification between the Antarctic nototheniid Notothenia rossii and the sub-Antarctic Lepidonotothen squamifrons, which share a similar ecology, but different habitat temperatures. After acclimation of L. squamifrons to 9°C and N. rossii to 7°C (normocapnic/hypercapnic, 0.2 kPa CO2/2000 ppm CO2) for 4-6 weeks, we compared the capacities of their mitochondrial respiratory complexes I (CI) and II (CII), their P/O ratios (phosphorylation efficiency), proton leak capacities and mitochondrial membrane fatty acid compositions. Our results reveal reduced CII respiration rates in warm-acclimated L. squamifrons and cold hypercapnia-acclimated N. rossii. Generally, L. squamifrons displayed a greater ability to increase CI contribution during acute warming and after warm-acclimation than N. rossii. Membrane unsaturation was not altered by warm or hypercapnia-acclimation in both species, but membrane fatty acids of warm-acclimated L. squamifrons were less saturated than in warm normocapnia-/hypercapnia-acclimated N. rossii. Proton leak capacities were not affected by warm or hypercapnia-acclimation of N. rossii. We conclude that an acclimatory response of mitochondrial capacities may include higher thermal plasticity of CI supported by enhanced utilization of anaplerotic substrates (via oxidative decarboxylation reactions) feeding into the citrate cycle. L. squamifrons possesses higher relative CI plasticities than N. rossii, which may facilitate the usage of energy efficient NADH-related substrates under conditions of elevated energy demand, possibly induced by ocean warming and acidification. The observed adjustments of electron transport system complexes with a higher flux through CI under warming and acidification suggest a metabolic acclimation potential of the sub-Antarctic L. squamifrons, but only limited acclimation capacities for N. rossii