Trimetazidine reduces basal cytosolic Ca(2+) concentration during hypoxia in single Xenopus skeletal myocytes

We tested the hypotheses that: (1) Ca2+ handling and force production would be irreversibly altered in skeletal muscle during steady-state contractions when subjected to severe, prolonged hypoxia and subsequent reoxygenation; and (2) application of the cardio-protective drug trimetazidine would attenuate these alterations. Single, living skeletal muscle fibres from Xenopus laevis were injected with the Ca2+ indicator fura 2, and incubated for 1 h prior to stimulation in 100 \u3bcm TMZ-Ringer solution (TMZ; n = 6) or standard Ringer solution (CON; n = 6). Force and relative free cytosolic Ca2+ concentration ([Ca2+]c) were measured during continuous tetanic contractions produced every 5 s as fibres were sequentially perfused in the following manner: 3 min high extracellular Po2 (159 mmHg), 15 min hypoxic perfusion (3-5 mmHg) then 3 min high Po2. Hypoxia caused a decrease in force and peak [Ca2+]c in both the TMZ and CON fibres, with no significant (P < 0.05) difference between groups. However, basal [Ca2+]c was significantly lower during hypoxia in the TMZ group vs. the CON group. While reoxygenation generated only modest recovery of relative force and peak [Ca2+]c in both groups, basal [Ca2+]c remained significantly less in the TMZ group. These results demonstrated that in contracting, single skeletal muscle fibres, TMZ prevented increases in basal [Ca2+]c generated during a severe hypoxic insult and subsequent reoxygenation, yet failed to protect the cell from the deleterious effects of prolonged hypoxia followed by reoxygenation

Data from: Crossing the line: tunas actively exploit submesoscale fronts to enhance foraging success

Fronts – i.e., the boundaries between water masses – are ubiquitous in the world oceans and have been shown to significantly influence pelagic ecosystems with enhanced local productivity and increased abundances of forage fish and top predators. Here we use data from archival tags to document how four juvenile albacore tunas foraged at and exploited a thermal front. Of the 3,098 observed trips, the albacore mainly swam across the front between the warm side above the thermocline and the cold side below the thermocline with an average of 78 ± 20.4 cross-frontal trips per fish per day. The warm frontal surface waters provided a thermal resource, allowing the tuna to maintain higher body temperatures and thus forage more efficiently in the food-rich waters of the cold side of the front. Foraging success of the tunas decreased as the cross-front thermal gradient weakened. This first look into small-scale use of fronts by a top predator demonstrates that ephemeral, submesoscale oceanic features can play a significant role in pelagic ecology

Pelagic Habitat Analysis Module (PHAM) for GIS Based Fisheries Decision Support

We have assembled a system that integrates satellite and model output with fisheries data We have developed tools that allow analysis of the interaction between species and key environmental variables Demonstrated the capacity to accurately map habitat of Thresher Sharks Alopias vulpinus & pelagicus. Their seasonal migration along the California Current is at least partly driven by the seasonal migration of sardine, key prey of the sharks.We have assembled a system that integrates satellite and model output with fisheries data We have developed tools that allow analysis of the interaction between species and key environmental variables Demonstrated the capacity to accurately map habitat of Thresher Sharks Alopias vulpinus nd pelagicus. Their seasonal migration along the California Current is at least partly driven by the seasonal migration of sardine, key prey of the sharks

Natural tracers reveal population structure of albacore (Thunnus alalunga) in the eastern North Pacific

Chemical signatures in otoliths and muscle tissue of albacore (Thunnus alalunga) from two regions of the North Pacific were characterized to examine population structure. Regions included northern (offshore northwest United States and Canada, .408N) and southern (offshore southwest United States and Mexico, ,408N) areas where albacore have demonstrated region-specific differences in movement and size at age. Juvenile (ages 1-4 years) albacore were collected from each region through recreational and commercial fisheries over a 5-year period (2009 -2013). Three different otolith chemistry assays were performed, including whole otoliths (proxy for lifetime signature), otolith edge (recent signature), and otolith core (nursery signature). Whole otolith 18 O showed similar results as whole otoliths, but no regional differences were found for otolith core chemistry. Incorporation of trace element concentrations from whole otoliths improved discrimination between regions to 90-100% classification success during each year of the study, with significantly higher Ba:Ca, Mg:Ca, and Mn:Ca in albacore otoliths from the northern region. Albacore from the southern region also displayed enriched muscle d N was 91%. Ultimately, results from this study suggest regional separation of albacore in the eastern North Pacific warranting region-specific vital rates in future modelling efforts

Overview of Fisheries Habitat Prediction Using the Pelagic Habitat Analysis Module (PHAM)

No abstract availabl

Insights into the life history and ecology of a large shortfin mako shark Isurus oxyrinchus captured in southern California

In June 2013, a record-breaking female Isurus oxyrinchus (total length 373 cm, mass 600 kg) was captured by rod and reel off Huntington Beach, California, where it was subsequently donated to research and provided a rare opportunity to collect the first data for a female I. oxyrinchus of this size. Counts of vertebral band pairs estimate the shark to have been c. 22 years old, depending upon assumptions of band-pair deposition rates, and the distended uteri and spent ovaries indicated that this shark had recently given birth. The stomach contained a c. 4 year-old female California sea lion Zalophus californianus that confirmed the high trophic position of this large I. oxyrinchus, which was corroborated with the high levels of measured contaminants and tissue isotope analyses

Effects of forced diving on the spleen and hepatic sinus in northern elephant seal pups

In phocid seals, an increase in hematocrit (Hct) accompanies diving and periods of apnea. The variability of phocid Hct suggests that the total red cell mass is not always in circulation, leading researchers to speculate on the means of blood volume partitioning. The histology and disproportionate size of the phocid spleen implicates it as the likely site for RBC storage. We used magnetic resonance imaging on Northern elephant seals to demonstrate a rapid contraction of the spleen and a simultaneous filling of the hepatic sinus during forced dives (P < 0.0001, R(2) = 0.97). The resulting images are clear evidence demonstrating a functional relationship between the spleen and hepatic sinus. The transfer of blood from the spleen to the sinus provides an explanation for the disparity between the timing of diving-induced splenic contraction (≈1–3 min) and the occurrence of peak Hct (15–25 min). Facial immersion was accompanied by an immediate and profound splenic contraction, with no further significant decrease in splenic volume after min 2 (Tukey–Kramer HSD, P = 0.05). At the conclusion of the dive, the spleen had contracted to 16% of its predive volume (mean resting splenic volume = 3,141 ml ± 68.01 ml; 3.54% of body mass). In the postdive period, the spleen required 18–22 min to achieve resting volume, indicating that this species may not have sufficient time to refill the spleen when routinely diving at sea, which is virtually continuous with interdive surface intervals between 1 and 3 min