Publications by authors named "Benjamin Negrete"
Hypoxia-acclimation adjusts skeletal muscle anaerobic metabolism and burst swim performance in a marine fish.
Comp Biochem Physiol A Mol Integr Physiol
November 2024
Article Synopsis
- Red drum fish can adapt to low oxygen environments by improving their aerobic performance, but the effects on their anaerobic metabolism and recovery after exercise are still unclear.
- Juvenile red drum were acclimated to either normal or hypoxic conditions and tested at rest, after exercise, and after recovery, showing that hypoxia acclimated fish had different metabolic responses, particularly in muscle tissue.
- The study found that hypoxia-acclimated fish exhibited higher pH levels and altered enzyme activity, suggesting they relied more on anaerobic metabolism during lower-intensity swimming compared to control fish, but did not show better recovery after exhaustive exercise.
Article Synopsis
- Respiratory plasticity in red drum fish allows them to adapt beneficially to chronic low oxygen levels encountered in their natural Gulf of Mexico habitat.
- A study exposed red drum embryos to either low or normal oxygen levels for three days post-fertilization, revealing no immediate differences in survival or size.
- After being reared in normoxic conditions, hypoxia-exposed fish showed improved aerobic capacity but also increased sensitivity to hypoxia, indicating a complex impact of early hypoxic exposure on their future swimming performance and metabolic efficiency.
Article Synopsis
- Ocean warming poses a significant threat to marine ectotherms, and the "plastic floors, concrete ceilings" hypothesis suggests that fish can reduce their standard metabolic rate (SMR) in warmer temperatures to improve their aerobic scope (AS).
- The study on red drum fish showed that while fish acclimated to 28°C had higher SMR and maximum metabolic rate (MMR) initially, SMR decreased significantly over 12 weeks, leading to no improvement in AS due to a drop in MMR.
- Additionally, hypoxia vulnerability measures indicated that warming reduces the critical oxygen threshold (P) in acclimated fish, which could help them adapt to high-demand environments, thereby expanding the range of habitats
Hypoxia acclimation improves mitochondrial efficiency in the aerobic swimming muscle of red drum (Sciaenops ocellatus).
Comp Biochem Physiol A Mol Integr Physiol
August 2023
Environmental hypoxia (low dissolved oxygen) is a significant threat facing fishes. As fishes require oxygen to efficiently produce ATP, hypoxia can significantly limit aerobic capacity. However, some fishes show respiratory flexibility that rescues aerobic performance, including plasticity in mitochondrial performance.
View Article and Find Full Text PDFThe effects of size on exhaustive exercise and recovery in a marine sportfish, the red drum (Sciaenops ocellatus).
Comp Biochem Physiol B Biochem Mol Biol
April 2023
Article Synopsis
- * This study focused on the injury and recovery profiles of two size classes of red drum fish (small: 20-30 cm, slot: 51-74 cm) after intense exercise, observing significant differences in recovery times between the two sizes.
- * Results indicate that while both size classes experience similar injury profiles after exhaustive exercise, slot-sized fish suffer more severe injuries and take longer to recover compared to smaller fish, suggesting they are at greater risk from intense angling activities.
With the growing prevalence of hypoxia (O2 levels ≤2 mg l-1) in aquatic and marine ecosystems, there is increasing interest in the adaptive mechanisms fish may employ to better their performance in stressful environments. Here, we investigated the contribution of a proposed strategy for enhancing tissue O2 extraction - plasma-accessible carbonic anhydrase (CA-IV) - under hypoxia in a species of estuarine fish (red drum, Sciaenops ocellatus) that thrives in fluctuating habitats. We predicted that hypoxia-acclimated fish would increase the prevalence of CA-IV in aerobically demanding tissues to confer more efficient tissue O2 extraction.
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- Ocean deoxygenation due to climate change prompts fish to adapt by regulating hemoglobin (Hb) expression for better oxygen uptake.
- Research focused on red drum fish showed significant up-regulation of a specific Hb subunit (hbα 2) within just 4 days of acclimation to low oxygen conditions.
- The increased Hb expression and changes in oxygen binding led to higher metabolic rates and improved aerobic performance in hypoxic environments, highlighting how Hb diversity aids fish in respiratory efficiency under stress.
The metabolic index concept combines metabolic data and known thermal sensitivities to estimate the factorial aerobic scope of animals in different habitats, which is valuable for understanding the metabolic demands that constrain species' geographical distributions. An important assumption of this concept is that the O2 supply capacity (which is equivalent to the rate of oxygen consumption divided by the environmental partial pressure of oxygen: ) is constant at O2 tensions above the critical O2 threshold (i.e.
View Article and Find Full Text PDFOne measure of hypoxia tolerance is the critical oxygen threshold, P, which is the point where standard metabolism can no longer be maintained through aerobic processes. Traditionally, P was determined using closed respirometry, whereby the fish's respiration naturally lowered O More recently, intermittent flow techniques have been adopted, where N is used to displace O, which ostensibly reduces end-product build-up. This study used a paired design on the marine teleost, red drum.
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