Cardiac function in Atlantic cod (Gadus morhua) as a function acclimation temperature and during acute thermal challenge

Cardiac function has been hypothesised to be a primary factor influencing swimming performance in teleost fish. Using the in situ perfused heart (Farrell) set-up we examined cardiac function in cod acclimated to 0, 4 and 10°C. Only small differences in maximal cardiac output (Qmax) and the maximal myocardial power (max PO) tests were seen between 4 and 10°C acclimated cod with regards to cardiac output (CO) and maximum power generated, and these were primarily due to significant chrontropic rather than inotropic effects. In both the Qmax and max PO tests, the cardiac output was significantly lower in the 0°C cod compared to the 10°C cod. Again this was due to significant chronotropic effects. Through acute temperature reversal, i.e. 10°C cod at 4°C and the 4°C cod at 10°C we found CO to be significantly larger in 4°C cod at 10°C compared to 10°C cod at 10°C, again due primarily to a significant increase in HR during the Qmax test, although SV also tended to be greater. Again the CO and maximum power generated during the max PO test were significantly elevated, however this was due to alterations in both SV and HR. It appears that heart rate alone is responsible for regulation of CO and power generation in cod when challenged at their acclimation temperatures, while SV remains constant. During the acute temperature change it seems that both the HR and SV are altered to maintain and in fact increase CO

In situ cardiac performance of Atlantic cod (Gadus morhua) at cold temperatures: long-term acclimation, acute thermal challenge and the role of adrenaline

The resting and maximum in situ cardiac performance of Newfoundland Atlantic cod (Gadus morhua) acclimated to 10, 4 and 0°C were measured at their respective acclimation temperatures, and when acutely exposed to temperature changes: i.e. hearts from 10°C fish cooled to 4°C, and hearts from 4°C fish measured at 10 and 0°C. Intrinsic heart rate (f(H)) decreased from 41 beats min(-1) at 10°C to 33 beats min(-1) at 4°C and 25 beats min(-1) at 0°C. However, this degree of thermal dependency was not reflected in maximal cardiac output (Q(max) values were ~44, ~37 and ~34 ml min(-1) kg(-1) at 10, 4 and 0°C, respectively). Further, cardiac scope showed a slight positive compensation between 4 and 0°C (Q(10)=1.7), and full, if not a slight over compensation between 10 and 4°C (Q(10)=0.9). The maximal performance of hearts exposed to an acute decrease in temperature (i.e. from 10 to 4°C and 4 to 0°C) was comparable to that measured for hearts from 4°C- and 0°C-acclimated fish, respectively. In contrast, 4°C-acclimated hearts significantly out-performed 10°C-acclimated hearts when tested at a common temperature of 10°C (in terms of both Q(max) and power output). Only minimal differences in cardiac function were seen between hearts stimulated with basal (5 nmol l(-1)) versus maximal (200 nmol l(-1)) levels of adrenaline, the effects of which were not temperature dependent. These results: (1) show that maximum performance of the isolated cod heart is not compromised by exposure to cold temperatures; and (2) support data from other studies, which show that, in contrast to salmonids, cod cardiac performance/myocardial contractility is not dependent upon humoral adrenergic stimulation

Mitochondrial plasticity in brachiopod (Liothyrella spp.) smooth adductor muscle as a result of season and latitude

Habitat temperature and mitochondrial volume density (Vv(mt,mf)) are negatively correlated in fishes, while seasonal acclimatization may increase Vv(mt,mf) or the surface density of the mitochondrial cristae (Sv(im,mt)). The effect of temperature on invertebrate mitochondria is essentially unknown. A comparison of two articulate brachiopod species, Liothyrella uva collected from Rothera Station, Antarctica in summer 2007, and Liothyrella neozelanica collected from Fiordland, New Zealand in winter 2007 and summer 2008, revealed a higher Vv(mt,mf) in the Antarctic brachiopod. The Sv(im,mt) was, however, significantly lower, indicating the Antarctic brachiopods have more, less reactive mitochondria. L. uva, from the colder environment, had larger adductor muscles in both absolute and relative terms than the temperate L. neozelanica. Furthermore, a seasonal comparison (winter vs. summer) in L. neozelanica showed that the absolute and relative size of the adductor increased in winter, Vv(mt,mf) was unchanged, and Sv(im,mt) was significantly increased. Thus, seasonal acclimatization to the cold resulted in the same number of more reactive mitochondria. L. neozelanica was clearly able to adapt to seasonal changes using a different mechanism, i.e. primarily through regulation of cristae surface area as opposed to mitochondrial volume density. Furthermore, given the evolutionary age of these living fossils (i.e. approximately 550 million years), this suggests that mitochondrial plasticity has roots extending far back into evolutionary history

Maternal immune response and air pollution exposure during pregnancy: insights from the Early Markers for Autism (EMA) study.

BackgroundPerinatal exposure to air pollution and immune system dysregulation are two factors consistently associated with autism spectrum disorders (ASD) and other neurodevelopmental outcomes. However, little is known about how air pollution may influence maternal immune function during pregnancy.ObjectivesTo assess the relationship between mid-gestational circulating levels of maternal cytokines/chemokines and previous month air pollution exposure across neurodevelopmental groups, and to assess whether cytokines/chemokines mediate the relationship between air pollution exposures and risk of ASD and/or intellectual disability (ID) in the Early Markers for Autism (EMA) study.MethodsEMA is a population-based, nested case-control study which linked archived maternal serum samples collected during weeks 15-19 of gestation for routine prenatal screening, birth records, and Department of Developmental Services (DDS) records. Children receiving DDS services for ASD without intellectual disability (ASD without ID; n = 199), ASD with ID (ASD with ID; n = 180), ID without ASD (ID; n = 164), and children from the general population (GP; n = 414) with no DDS services were included in this analysis. Serum samples were quantified for 22 cytokines/chemokines using Luminex multiplex analysis technology. Air pollution exposure for the month prior to maternal serum collection was assigned based on the Environmental Protection Agency's Air Quality System data using the maternal residential address reported during the prenatal screening visit.ResultsPrevious month air pollution exposure and mid-gestational maternal cytokine and chemokine levels were significantly correlated, though weak in magnitude (ranging from - 0.16 to 0.13). Ten pairs of mid-pregnancy immune markers and previous month air pollutants were significantly associated within one of the child neurodevelopmental groups, adjusted for covariates (p < 0.001). Mid-pregnancy air pollution was not associated with any neurodevelopmental outcome. IL-6 remained associated with ASD with ID even after adjusting for air pollution exposure.ConclusionThis study suggests that maternal immune activation is associated with risk for neurodevelopmental disorders. Furthermore, that prenatal air pollution exposure is associated with small, but perhaps biologically relevant, effects on maternal immune system function during pregnancy. Additional studies are needed to better evaluate how prenatal exposure to air pollution affects the trajectory of maternal immune activation during pregnancy, if windows of heightened susceptibility can be identified, and how these factors influence neurodevelopment of the offspring

Oxygen consumption during digestion in Anodonta anatina and Unio pictorum in response to algal concentration

Abstract The metabolic activity of unionid mussels influences the oxygen fluxes and other physical and chemical characteristics in aquatic systems. Unionid oxygen consumption rate during digestion and its dependency on food availability is understudied. In laboratory conditions, we quantified the oxygen consumption rate of Anodonta anatina and Unio pictorum in response to algal concentration—0.05, 6.0 and 12.0 mg of Ash Free Dry Mass of Chlorella vulgaris L-1 —and mussel dry soft-tissue mass at 19 ± 1C. Following a 5-h feeding-period, the oxygen consumption rate (mg O2 h-1 ) increased with algal concentration and mussel dry mass in both species during a 2-h digestion-period. The mean oxygen consumption per gram of dry mass (mg O2 gDM-1 h-1 ) increased with the algal concentration in both species. The oxygen consumption rate of A. anatina was significantly greater than that of U. pictorum at a given algal concentration. The A. anatina oxygen consumption per gram of dry mass decreased with increasing dry mass. Oxygen consumption rate during digestion shows inter-specific differences and is dependent on food availability. The findings inform the species specific quantification of oxygen consumption, and validation is required in in situ conditions.This work was funded by an ESRC PhD studentshi

Ultrastructure of pedal muscle as a function of temperature in nacellid limpets

Temperature and mitochondrial plasticity are well studied in fishes, but little is known about this relationship in invertebrates. The effects of habitat temperature on mitochondrial ultrastructure were examined in three con-familial limpets from the Antarctic (Nacella concinna), New Zealand (Cellana ornata), and Singapore (Cellana radiata). The effects of seasonal changes in temperature were also examined in winter and summer C. ornata. Stereological methods showed that limpet pedal myocytes were 1–2 orders of magnitude smaller in diameter (≈3.5 μm) than in vertebrates, and that the diameter did not vary as a function of temperature. Mitochondrial volume density (Vv(mt,f)) was approximately 2–4 times higher in N. concinna (0.024) than in the other species (0.01 and 0.006), which were not significantly different from each other. Mitochondrial cristae surface density (Sv(im,mt)) was significantly lower in summer C. ornata (24.1 ± 0.50 μm2 μm−3) than both winter C. ornata (32.3 ± 0.95 μm2 μm−3) and N. concinna (34.3 ± 4.43 μm2 μm−3). The surface area of mitochondrial cristae per unit fibre volume was significantly higher in N. concinna, due largely to the greater mitochondrial volume density. These results and previous studies indicate that mitochondrial proliferation in the cold is a common, but not universal response by different species from different thermal habitats. Seasonal temperature decreases on the other hand, leading preferentially to an increase in cristae surface density. Stereological measures also showed that energetic reserves, i.e. lipid droplets and glycogen in the pedal muscle changed greatly with season and species. This was most likely related to gametogenesis and spawning

Benzo(a)pyrene Metabolism and EROD and GST Biotransformation Activity in the Liver of Red- and White-Blooded Antarctic Fish.

Climate change and anthropogenic pollution are of increasing concern in remote areas such as Antarctica. The evolutionary adaptation of Antarctic notothenioid fish to the cold and stable Southern Ocean led to a low plasticity of their physiological functions, what may limit their capacity to deal with altered temperature regimes and pollution in the Antarctic environment. Using a biochemical approach, we aimed to assess the hepatic biotransformation capacities of Antarctic fish species by determining (i) the activities of ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST), and (ii) the metabolic clearance of benzo(a)pyrene by hepatic S9 supernatants. In addition, we determined the thermal sensitivity of the xenobiotic biotransformation enzymes. We investigated the xenobiotic metabolism of the red-blooded Gobionotothen gibberifrons and Notothenia rossii, the hemoglobin-less Chaenocephalus aceratus and Champsocephalus gunnari, and the rainbow trout Oncorhynchus mykiss as a reference. Our results revealed similar metabolic enzyme activities and metabolic clearance rates between red- and white-blooded Antarctic fish, but significantly lower rates in comparison to rainbow trout. Therefore, bioaccumulation factors for metabolizable lipophilic contaminants may be higher in Antarctic than in temperate fish. Likewise, the thermal adaptive capacities and flexibilities of the EROD and GST activities in Antarctic fish were significantly lower than in rainbow trout. As a consequence, increasing water temperatures in the Southern Ocean will additionally compromise the already low detoxification capacities of Antarctic fish