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Kathryn A Dickson - One of the best experts on this subject based on the ideXlab platform.

  • Mitochondrial proton leak rates in the slow, oxidative myotomal muscle and liver of the endothermic shortfin mako Shark (Isurus oxyrinchus) and the ectothermic blue Shark (Prionace glauca) and Leopard Shark (Triakis semifasciata).
    The Journal of experimental biology, 2020
    Co-Authors: Cindy A Duong, Chugey A Sepulveda, Jeffrey B. Graham, Kathryn A Dickson
    Abstract:

    Mitochondrial proton leak was assessed as a potential heat source in the slow, oxidative (red) locomotor muscle and liver of the shortfin mako Shark (Isurus oxyrinchus), a regional endotherm that maintains the temperature of both tissues elevated above ambient seawater temperature. We hypothesized that basal proton leak rates in red muscle and liver mitochondria of the endothermic shortfin mako Shark would be greater than those of the ectothermic blue Shark (Prionace glauca) and Leopard Shark (Triakis semifasciata). Respiration rate and membrane potential in isolated mitochondria were measured simultaneously at 20 degrees C using a Clark-type oxygen electrode and a lipophilic probe (triphenylmethylphosphonium, TPMP(+)). Succinate-stimulated respiration was titrated with inhibitors of the electron transport chain, and the non-linear relationship between respiration rate and membrane potential was quantified. Mitochondrial densities of both tissues were measured by applying the point-contact method to electron micrographs so that proton leak activity of the entire tissue could be assessed. In all three Shark species, proton leak occurred at a higher rate in red muscle mitochondria than in liver mitochondria. For each tissue, the proton leak curves of the three species overlapped and, at a membrane potential of 160 mV, mitochondrial proton leak rate (nmol H(+) min(-1) mg(-1) protein) did not differ significantly between the endothermic and ectothermic Sharks. This finding indicates that red muscle and liver mitochondria of the shortfin mako Shark are not specialized for thermogenesis by having a higher proton conductance. However, mako mitochondria did have higher succinate-stimulated respiration rates and membrane potentials than those of the two ectothermic Sharks. This means that under in vivo conditions mitochondrial proton leak rates may be higher in the mako than in the ectothermic species, due to greater electron transport activity and a larger proton gradient driving proton leak. We also estimated each tissue's total proton leak by combining mitochondrial proton leak rates at 160 mV and tissue mitochondrial density data with published values of relative liver or red muscle mass for each of the three species. In red muscle, total proton leak was not elevated in the mako Shark relative to the two ectothermic species. In the liver, total proton leak would be higher in the mako Shark than in both ectothermic species, due to a lower proton conductance in the blue Shark and a lower liver mitochondrial content in the Leopard Shark, and thus may contribute to endothermy.

  • Jeffrey B. Graham 26 November 1941 – 8 December 2011
    The Journal of Experimental Biology, 2012
    Co-Authors: Kathryn A Dickson, Troy A. Baird, Nicholas C. Wegner
    Abstract:

    ![Fig. 1.][1] Fig. 1. Graduate student William Lowell (left) and Jeff Graham conducting an experiment on a Leopard Shark, Triakis semifasciata , in a swimming tunnel respirometer (one version of the ElasmoTunaTron) at Scripps Institution of Oceanography, circa 1980. Photo from Scripps

  • mitochondrial proton leak rates in the slow oxidative myotomal muscle and liver of the endothermic shortfin mako Shark isurus oxyrinchus and the ectothermic blue Shark prionace glauca and Leopard Shark triakis semifasciata
    The Journal of Experimental Biology, 2006
    Co-Authors: Cindy A Duong, Chugey A Sepulveda, Jeffrey B. Graham, Kathryn A Dickson
    Abstract:

    Mitochondrial proton leak was assessed as a potential heat source in the slow, oxidative (red) locomotor muscle and liver of the shortfin mako Shark ( Isurus oxyrinchus ), a regional endotherm that maintains the temperature of both tissues elevated above ambient seawater temperature. We hypothesized that basal proton leak rates in red muscle and liver mitochondria of the endothermic shortfin mako Shark would be greater than those of the ectothermic blue Shark ( Prionace glauca ) and Leopard Shark ( Triakis semifasciata ). Respiration rate and membrane potential in isolated mitochondria were measured simultaneously at 20°C using a Clark-type oxygen electrode and a lipophilic probe (triphenylmethylphosphonium, TPMP+). Succinate-stimulated respiration was titrated with inhibitors of the electron transport chain, and the non-linear relationship between respiration rate and membrane potential was quantified. Mitochondrial densities of both tissues were measured by applying the point-contact method to electron micrographs so that proton leak activity of the entire tissue could be assessed. In all three Shark species, proton leak occurred at a higher rate in red muscle mitochondria than in liver mitochondria. For each tissue, the proton leak curves of the three species overlapped and, at a membrane potential of 160 mV, mitochondrial proton leak rate (nmol H+ min-1 mg-1 protein) did not differ significantly between the endothermic and ectothermic Sharks. This finding indicates that red muscle and liver mitochondria of the shortfin mako Shark are not specialized for thermogenesis by having a higher proton conductance. However, mako mitochondria did have higher succinate-stimulated respiration rates and membrane potentials than those of the two ectothermic Sharks. This means that under in vivo conditions mitochondrial proton leak rates may be higher in the mako than in the ectothermic species, due to greater electron transport activity and a larger proton gradient driving proton leak. We also estimated each tissue's total proton leak by combining mitochondrial proton leak rates at 160 mV and tissue mitochondrial density data with published values of relative liver or red muscle mass for each of the three species. In red muscle, total proton leak was not elevated in the mako Shark relative to the two ectothermic species. In the liver, total proton leak would be higher in the mako Shark than in both ectothermic species, due to a lower proton conductance in the blue Shark and a lower liver mitochondrial content in the Leopard Shark, and thus may contribute to endothermy.

  • effects of endurance training in the Leopard Shark triakis semifasciata
    Physiological and Biochemical Zoology, 1997
    Co-Authors: Stephen J Gruber, Kathryn A Dickson
    Abstract:

    ABSTRACT This study is the first to examine the effects of endurance training in an elasmobranch fish. Twenty‐four Leopard Sharks (Triakis semifasciata) were divided randomly into three groups. Eight Sharks were killed immediately, eight were forced to swim continuously for 6 wk against a current of 35 cm s−1 (60%–65% of maximal sustainable swimming speed), and eight were held for 6 wk in a tank without induced current. There were no changes due to training in maximal sustainable speed, oxygen consumption rates, percentage of the myotome composed of red and white muscle fibers, blood oxygen‐carrying capacity, liver mass, liver lipid, glycogen, and protein concentrations, white muscle protein content, heart ventricle mass, or the specific activities of the enzymes citrate synthase, pyruvate kinase, and lactate dehydrogenase in the heart ventricle. In red myoto‐mal muscle, citrate synthase activity increased 17% as a result of training, but there was no change in muscle fiber diameter. The greatest effects ...

Chugey A Sepulveda - One of the best experts on this subject based on the ideXlab platform.

  • Thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark.
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus. The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25 degrees C for Triakis and 15 to 28 degrees C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6-0.65 L) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (

  • Mitochondrial proton leak rates in the slow, oxidative myotomal muscle and liver of the endothermic shortfin mako Shark (Isurus oxyrinchus) and the ectothermic blue Shark (Prionace glauca) and Leopard Shark (Triakis semifasciata).
    The Journal of experimental biology, 2020
    Co-Authors: Cindy A Duong, Chugey A Sepulveda, Jeffrey B. Graham, Kathryn A Dickson
    Abstract:

    Mitochondrial proton leak was assessed as a potential heat source in the slow, oxidative (red) locomotor muscle and liver of the shortfin mako Shark (Isurus oxyrinchus), a regional endotherm that maintains the temperature of both tissues elevated above ambient seawater temperature. We hypothesized that basal proton leak rates in red muscle and liver mitochondria of the endothermic shortfin mako Shark would be greater than those of the ectothermic blue Shark (Prionace glauca) and Leopard Shark (Triakis semifasciata). Respiration rate and membrane potential in isolated mitochondria were measured simultaneously at 20 degrees C using a Clark-type oxygen electrode and a lipophilic probe (triphenylmethylphosphonium, TPMP(+)). Succinate-stimulated respiration was titrated with inhibitors of the electron transport chain, and the non-linear relationship between respiration rate and membrane potential was quantified. Mitochondrial densities of both tissues were measured by applying the point-contact method to electron micrographs so that proton leak activity of the entire tissue could be assessed. In all three Shark species, proton leak occurred at a higher rate in red muscle mitochondria than in liver mitochondria. For each tissue, the proton leak curves of the three species overlapped and, at a membrane potential of 160 mV, mitochondrial proton leak rate (nmol H(+) min(-1) mg(-1) protein) did not differ significantly between the endothermic and ectothermic Sharks. This finding indicates that red muscle and liver mitochondria of the shortfin mako Shark are not specialized for thermogenesis by having a higher proton conductance. However, mako mitochondria did have higher succinate-stimulated respiration rates and membrane potentials than those of the two ectothermic Sharks. This means that under in vivo conditions mitochondrial proton leak rates may be higher in the mako than in the ectothermic species, due to greater electron transport activity and a larger proton gradient driving proton leak. We also estimated each tissue's total proton leak by combining mitochondrial proton leak rates at 160 mV and tissue mitochondrial density data with published values of relative liver or red muscle mass for each of the three species. In red muscle, total proton leak was not elevated in the mako Shark relative to the two ectothermic species. In the liver, total proton leak would be higher in the mako Shark than in both ectothermic species, due to a lower proton conductance in the blue Shark and a lower liver mitochondrial content in the Leopard Shark, and thus may contribute to endothermy.

  • Patterns of red muscle strain/activation and body kinematics during steady swimming in a lamnid Shark, the shortfin mako (Isurus oxyrinchus).
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Peter Konstantinidis, Sven Gemballa
    Abstract:

    The dynamics of steady swimming were examined in the shortfin mako (Isurus oxyrinchus), a member of the cartilaginous fish family Lamnidae, a family known for their morphological adaptations for high-performance locomotion and their similarity in hydromechanical design to tunas. Patterns of red muscle (RM) strain (i.e. relative length change) and activation were quantified at two axial positions ( approximately 0.4 and 0.6L, where L is total body length), using sonomicrometry and electromyography (EMG), and correlated with simultaneous measurements of dorsal midline kinematics during steady swimming ( approximately 0.5-1 L s(-1)). RM strain varied longitudinally with strain amplitudes ranging from 5.5+/-1.1% (s.e.m.) in the anterior to 8.7+/-0.9% in the posterior. We found no significant longitudinal variation in patterns of RM activation, with mean onset of activation occurring at 83-84 degrees (90 degrees is peak length) and offset at 200-210 degrees at both body positions. Likewise, duty cycles were similar: 35.5+/-1.0% in the anterior and 32.2+/-1.6% in the posterior. Comparison of the timing of waves of dorsal midline curvature and predicted strain relative to measured RM strain revealed a phase shift between RM shortening and local body bending. Furthermore, when the body is bent passively, RM shortens synchronously with the surrounding white muscle (WM) and skin, as expected. During active swimming, peaks in RM strain were delayed relative to peaks in WM strain by a mean of approximately 10% of the tailbeat cycle, with one individual as high as approximately 17% in the anterior and nearly 50% in the posterior. The longitudinal consistency in the EMG/strain phase relationship in the mako is similar to that in the Leopard Shark, suggesting a consistent trend among Sharks using different locomotor modes. However, unlike in the Leopard Shark, RM shortening in the mako is physically uncoupled from deformation of the surrounding body during steady swimming, a characteristic shared between the mako and tunas.

  • Temperature effects on the blood oxygen affinity in Sharks.
    Fish Physiology and Biochemistry, 2018
    Co-Authors: Diego Bernal, Joseph J. Cech, Chugey A Sepulveda, Joseph P. Reid, Julie M. Roessig, Shinsyu Matsumoto, Jeffrey B. Graham
    Abstract:

    In fish, regional endothermy (i.e., the capacity to significantly elevate tissue temperatures above ambient via vascular heat exchangers) in the red swimming muscles (RM) has evolved only in a few marine groups (e.g., Sharks: Lamnidae, Alopiidae, and teleosts Scombridae). Within these taxa, several species have also been shown to share similar physiological adaptations to enhance oxygen delivery to the working tissues. Although the hemoglobin (Hb) of most fish has a decreased affinity for oxygen with an increase in temperature, some regionally endothermic teleosts (e.g., tunas) have evolved Hbs that have a very low or even an increased affinity for oxygen with an increase in temperature. For Sharks, however, blood oxygen affinities remain largely unknown. We examined the effects of temperature on the blood oxygen affinity in two pelagic species (the regionally endothermic shortfin mako Shark and the ectothermic blue Shark) at 15, 20, and 25 °C, and two coastal ectothermic species (the Leopard Shark and brown smooth-hound Shark) at 10, 15, and 20 °C. Relative to the effects of temperature on the blood oxygen affinity of ectothermic Sharks (e.g., blue Shark), shortfin mako Shark blood was less affected by an increase in temperature, a scenario similar to that documented in some of the tunas. In the shortfin mako Shark, this may act to prevent premature oxygen dissociation from Hb as the blood is warmed during its passage through vascular heat exchangers. Even though the shortfin mako Shark and blue Shark occupy a similar niche, the effects of temperature on blood oxygen affinity in the latter more closely resembled that of the blood in the two coastal Shark species examined in this study. The only exception was a small, reverse temperature effect (an increase in blood oxygen affinity with temperature) observed during the warming of the Leopard Shark blood under simulated arterial conditions, a finding that is likely related to the estuarine ecology of this species. Taken together, we found species-specific differences in how temperature affects blood oxygen affinity in Sharks, with some similarities between the regionally endothermic Sharks and several regionally endothermic teleost fishes.

  • thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark
    The Journal of Experimental Biology, 2007
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus . The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25°C for Triakis and 15 to 28°C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6–0.65 L ) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (<20°C). We found no significant differences in optimal stimulus duration, phase, net work or power output between anterior and posterior bundles in each species. With increasing cycle frequency the stimulus duration yielding maximum power decreased while optimal phase occurred earlier. The cycle frequency at which peak power was generated in Leopard Shark RM was only affected slightly by temperature, increasing from about 0.6 to 1.0 Hz between 15 and 25°C. In contrast, mako RM showed a much more dramatic temperature sensitivity, with the peak power frequency rising from <0.25 to 2.25 Hz between 15 and 28°C. These data support the hypothesis that the contractile properties of RM are functionally similar along the body in both species. In addition, our data identify a significant difference in the effect of temperature on net work and power output between these two Shark species; at 15°C muscle from the ectothermic Leopard Shark performs relatively well in comparison with mako, while at higher temperatures, which reflect those normally experienced by the mako, the optimal cycle frequency for power is nearly double that of the Leopard Shark, suggesting that the mako may be able to maintain greater aerobic swimming speeds.

Jeanine M Donley - One of the best experts on this subject based on the ideXlab platform.

  • Steady swimming muscle dynamics in the Leopard Shark Triakis semifasciata.
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick
    Abstract:

    Patterns of red muscle strain and activation were examined at three positions along the body (0.42, 0.61 and 0.72 L, where L is total body length) and correlated with simultaneous measurements of midline kinematics during steady swimming (approx. 1.0 L s(-1)) in the Leopard Shark Triakis semifasciata. Analysis of lateral displacement along the body indicates that the Leopard Shark is a subcarangiform swimmer. Longitudinal variation in red muscle strain was observed with strain amplitudes ranging from +/-3.9% in the anterior, +/-6.6% in the mid, to +/-4.8% in the posterior body position. Strain was in-phase with local midline curvature. In addition, strain amplitude calculated from a bending beam model closely matched strain measured using sonomicrometry at all three body positions. There is a high degree of similarity in red muscle activation patterns along the body between the Leopard Shark and many fish species, in that the onset of activation occurs during muscle lengthening while offset occurs during muscle shortening. However, we found no significant longitudinal variation in the EMG/strain phase relationship and duty cycles, with onset of muscle activation occurring at 51.4-61.8 degrees and offset at 159.7-165.2 degrees (90 degrees is peak length). This consistent pattern of activation suggests that red muscle along the entire length of the body contributes to positive power production. Thus, Sharks such as Triakis may have no regional specialization in red muscle function like that seen in many teleosts, which may indicate that the evolution of differential muscle function along the body occurred after the divergence of cartilaginous and bony fishes.

  • Thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark.
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus. The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25 degrees C for Triakis and 15 to 28 degrees C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6-0.65 L) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (

  • Patterns of red muscle strain/activation and body kinematics during steady swimming in a lamnid Shark, the shortfin mako (Isurus oxyrinchus).
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Peter Konstantinidis, Sven Gemballa
    Abstract:

    The dynamics of steady swimming were examined in the shortfin mako (Isurus oxyrinchus), a member of the cartilaginous fish family Lamnidae, a family known for their morphological adaptations for high-performance locomotion and their similarity in hydromechanical design to tunas. Patterns of red muscle (RM) strain (i.e. relative length change) and activation were quantified at two axial positions ( approximately 0.4 and 0.6L, where L is total body length), using sonomicrometry and electromyography (EMG), and correlated with simultaneous measurements of dorsal midline kinematics during steady swimming ( approximately 0.5-1 L s(-1)). RM strain varied longitudinally with strain amplitudes ranging from 5.5+/-1.1% (s.e.m.) in the anterior to 8.7+/-0.9% in the posterior. We found no significant longitudinal variation in patterns of RM activation, with mean onset of activation occurring at 83-84 degrees (90 degrees is peak length) and offset at 200-210 degrees at both body positions. Likewise, duty cycles were similar: 35.5+/-1.0% in the anterior and 32.2+/-1.6% in the posterior. Comparison of the timing of waves of dorsal midline curvature and predicted strain relative to measured RM strain revealed a phase shift between RM shortening and local body bending. Furthermore, when the body is bent passively, RM shortens synchronously with the surrounding white muscle (WM) and skin, as expected. During active swimming, peaks in RM strain were delayed relative to peaks in WM strain by a mean of approximately 10% of the tailbeat cycle, with one individual as high as approximately 17% in the anterior and nearly 50% in the posterior. The longitudinal consistency in the EMG/strain phase relationship in the mako is similar to that in the Leopard Shark, suggesting a consistent trend among Sharks using different locomotor modes. However, unlike in the Leopard Shark, RM shortening in the mako is physically uncoupled from deformation of the surrounding body during steady swimming, a characteristic shared between the mako and tunas.

  • thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark
    The Journal of Experimental Biology, 2007
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus . The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25°C for Triakis and 15 to 28°C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6–0.65 L ) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (<20°C). We found no significant differences in optimal stimulus duration, phase, net work or power output between anterior and posterior bundles in each species. With increasing cycle frequency the stimulus duration yielding maximum power decreased while optimal phase occurred earlier. The cycle frequency at which peak power was generated in Leopard Shark RM was only affected slightly by temperature, increasing from about 0.6 to 1.0 Hz between 15 and 25°C. In contrast, mako RM showed a much more dramatic temperature sensitivity, with the peak power frequency rising from <0.25 to 2.25 Hz between 15 and 28°C. These data support the hypothesis that the contractile properties of RM are functionally similar along the body in both species. In addition, our data identify a significant difference in the effect of temperature on net work and power output between these two Shark species; at 15°C muscle from the ectothermic Leopard Shark performs relatively well in comparison with mako, while at higher temperatures, which reflect those normally experienced by the mako, the optimal cycle frequency for power is nearly double that of the Leopard Shark, suggesting that the mako may be able to maintain greater aerobic swimming speeds.

  • Thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark
    The Journal of Experimental Biology, 2007
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus . The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25°C for Triakis and 15 to 28°C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6–0.65 L ) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (

Robert E Shadwick - One of the best experts on this subject based on the ideXlab platform.

  • Steady swimming muscle dynamics in the Leopard Shark Triakis semifasciata.
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick
    Abstract:

    Patterns of red muscle strain and activation were examined at three positions along the body (0.42, 0.61 and 0.72 L, where L is total body length) and correlated with simultaneous measurements of midline kinematics during steady swimming (approx. 1.0 L s(-1)) in the Leopard Shark Triakis semifasciata. Analysis of lateral displacement along the body indicates that the Leopard Shark is a subcarangiform swimmer. Longitudinal variation in red muscle strain was observed with strain amplitudes ranging from +/-3.9% in the anterior, +/-6.6% in the mid, to +/-4.8% in the posterior body position. Strain was in-phase with local midline curvature. In addition, strain amplitude calculated from a bending beam model closely matched strain measured using sonomicrometry at all three body positions. There is a high degree of similarity in red muscle activation patterns along the body between the Leopard Shark and many fish species, in that the onset of activation occurs during muscle lengthening while offset occurs during muscle shortening. However, we found no significant longitudinal variation in the EMG/strain phase relationship and duty cycles, with onset of muscle activation occurring at 51.4-61.8 degrees and offset at 159.7-165.2 degrees (90 degrees is peak length). This consistent pattern of activation suggests that red muscle along the entire length of the body contributes to positive power production. Thus, Sharks such as Triakis may have no regional specialization in red muscle function like that seen in many teleosts, which may indicate that the evolution of differential muscle function along the body occurred after the divergence of cartilaginous and bony fishes.

  • Thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark.
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus. The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25 degrees C for Triakis and 15 to 28 degrees C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6-0.65 L) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (

  • Patterns of red muscle strain/activation and body kinematics during steady swimming in a lamnid Shark, the shortfin mako (Isurus oxyrinchus).
    The Journal of experimental biology, 2020
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Peter Konstantinidis, Sven Gemballa
    Abstract:

    The dynamics of steady swimming were examined in the shortfin mako (Isurus oxyrinchus), a member of the cartilaginous fish family Lamnidae, a family known for their morphological adaptations for high-performance locomotion and their similarity in hydromechanical design to tunas. Patterns of red muscle (RM) strain (i.e. relative length change) and activation were quantified at two axial positions ( approximately 0.4 and 0.6L, where L is total body length), using sonomicrometry and electromyography (EMG), and correlated with simultaneous measurements of dorsal midline kinematics during steady swimming ( approximately 0.5-1 L s(-1)). RM strain varied longitudinally with strain amplitudes ranging from 5.5+/-1.1% (s.e.m.) in the anterior to 8.7+/-0.9% in the posterior. We found no significant longitudinal variation in patterns of RM activation, with mean onset of activation occurring at 83-84 degrees (90 degrees is peak length) and offset at 200-210 degrees at both body positions. Likewise, duty cycles were similar: 35.5+/-1.0% in the anterior and 32.2+/-1.6% in the posterior. Comparison of the timing of waves of dorsal midline curvature and predicted strain relative to measured RM strain revealed a phase shift between RM shortening and local body bending. Furthermore, when the body is bent passively, RM shortens synchronously with the surrounding white muscle (WM) and skin, as expected. During active swimming, peaks in RM strain were delayed relative to peaks in WM strain by a mean of approximately 10% of the tailbeat cycle, with one individual as high as approximately 17% in the anterior and nearly 50% in the posterior. The longitudinal consistency in the EMG/strain phase relationship in the mako is similar to that in the Leopard Shark, suggesting a consistent trend among Sharks using different locomotor modes. However, unlike in the Leopard Shark, RM shortening in the mako is physically uncoupled from deformation of the surrounding body during steady swimming, a characteristic shared between the mako and tunas.

  • thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark
    The Journal of Experimental Biology, 2007
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus . The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25°C for Triakis and 15 to 28°C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6–0.65 L ) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (<20°C). We found no significant differences in optimal stimulus duration, phase, net work or power output between anterior and posterior bundles in each species. With increasing cycle frequency the stimulus duration yielding maximum power decreased while optimal phase occurred earlier. The cycle frequency at which peak power was generated in Leopard Shark RM was only affected slightly by temperature, increasing from about 0.6 to 1.0 Hz between 15 and 25°C. In contrast, mako RM showed a much more dramatic temperature sensitivity, with the peak power frequency rising from <0.25 to 2.25 Hz between 15 and 28°C. These data support the hypothesis that the contractile properties of RM are functionally similar along the body in both species. In addition, our data identify a significant difference in the effect of temperature on net work and power output between these two Shark species; at 15°C muscle from the ectothermic Leopard Shark performs relatively well in comparison with mako, while at higher temperatures, which reflect those normally experienced by the mako, the optimal cycle frequency for power is nearly double that of the Leopard Shark, suggesting that the mako may be able to maintain greater aerobic swimming speeds.

  • Thermal dependence of contractile properties of the aerobic locomotor muscle in the Leopard Shark and shortfin mako Shark
    The Journal of Experimental Biology, 2007
    Co-Authors: Jeanine M Donley, Robert E Shadwick, Chugey A Sepulveda, Douglas A Syme
    Abstract:

    The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic Leopard Shark Triakis semifasciata and endothermic shortfin mako Shark Isurus oxyrinchus . The effects of axial position and temperature on the twitch kinetics, and the stimulus duration and phase producing maximum net positive work and power output were investigated. Contractile performance was measured over the temperature range of 15 to 25°C for Triakis and 15 to 28°C for Isurus at cycle frequencies (analogous to tailbeat frequencies) ranging from 0.25 to 3 Hz using muscle bundles isolated from anterior (0.4 L where L is total body length) and posterior (0.6–0.65 L ) axial positions. Pairwise comparisons of twitch times for anterior and posterior muscle samples indicated that there were no significant differences related to body position, except in mako Sharks at unphysiologically cool temperatures (

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  • SAC - Predicting coordinated group movements of Sharks with limited observations using AUVs
    Proceedings of the Symposium on Applied Computing - SAC '17, 2017
    Co-Authors: Cherie Ho, Christopher G. Lowe, Andrew P Nosal, Kimberly Joly, Christopher M Clark
    Abstract:

    This paper presents a method for modeling and then tracking the 2D planar size, location, orientation, and number of individuals of an animal aggregation using Autonomous Underwater Vehicles (AUVs). It is assumed that the AUVs are equipped with sensors that can measure the position states of a subset of individuals from within the aggregation being tracked. A new aggregation model based on provably stable Markov Process Matrices is shown as a viable model for representing aggregations. Then, a multi-stage state estimation architecture based on Particle Filters is presented that can estimate the time-varying model parameters in real-time using sensor measurements obtained by AUVs. To validate the approach, a historical data set is used consisting of >100 Shark trajectories from a Leopard Shark aggregation observed in the La Jolla, CA coast area. The method is generalizable to any stable group movement model constructed using a Markov Matrix. Simulation results show that, when at least 40+ of Sharks are tagged, the estimated number of Sharks in the aggregation has an error of 6+. This error increased to 27+ when the system was tested with real data.

  • Human vs robot: Comparing the viability and utility of autonomous underwater vehicles for the acoustic telemetry tracking of marine organisms
    Journal of Experimental Marine Biology and Ecology, 2016
    Co-Authors: Connor F. White, Christopher M Clark, Christopher G. Lowe
    Abstract:

    Currently, individual animal movement data can be obtained using a variety of methods, but each methodology is limited in either temporal or spatial resolution. A new method of active tracking was developed which utilizes autonomous underwater vehicles (AUV) equipped with stereo-hydrophones that can accurately estimate the position of a moving acoustic tag, while remaining at a distance. This technology was tested and compared to standard human-based active tracking technology to understand the benefits and limitations of this new technique. An AUV and a researcher independently tracked stationary and moving targets of known location in order to compare their spatial and temporal accuracy. Both methods were then used to track a Leopard Shark, Triakis semifasciata, in the field. The autonomous vehicle accurately positioned both stationary and moving tags with a positional error of < 10 m. For stationary transmitters, the AUV and the researcher were comparable, but when tracking moving transmitters, the AUV had significantly better spatial accuracy. Throughout all trials, the AUV had a higher frequency of accurate location estimates than a researcher actively tracking. Based on these findings, the AUV was able to more accurately track and record the position of an acoustically tagged Shark in the field. Using this new technology, researchers should be able to maintain or improve the spatial resolution of measurements when actively tracking acoustically tagged individuals and will be able to increase the temporal resolution of measurements while minimizing the potential influence of tracking on the behavior of the animal.

  • IROS - A multi-AUV state estimator for determining the 3D position of tagged fish
    2014 IEEE RSJ International Conference on Intelligent Robots and Systems, 2014
    Co-Authors: Hannah Kastein, Christopher G. Lowe, Connor F. White, Taylor Peterson, Christopher M Clark
    Abstract:

    This paper presents a multi-AUV state-estimator that can determine the 3D position of a tagged fish. In addition to angle measurements, the state-estimator also incorporates distance and depth measurements. These additional sensor measurements allow for greater accuracy in the position es- timates. A newly developed motion model that better accounts for multiple hypotheses of the motion of a tagged fish is used to increase the robustness of the state-estimator. A series of multi-AUV Shark tracks were conducted at Santa Catalina Island, California over the span of four days to demonstrate the ability of the state-estimator to determine the 3D position of a tagged Leopard Shark. Additional experiments in which the AUVs tracked a tagged boat of known location were conducted to quantify the performance of the presented state-estimator. Experimental results demonstrate a three-fold decrease in mean state-estimation error compared to previous works. I. INTRODUCTION Studying the spatial movement of Sharks and other fishes is an important tool for monitoring habitat and maintaining fish populations. Typical methods for tracking fish include tagging individuals with acoustic transmitters, and then using hydrophone-receiver systems to detect and measure the signals transmitted. Often, the hydrophone-receivers are placed at fixed locations around an environment of interest to passively track tagged individuals that move through the static array (1). Alternatively, active tracking can be done manually by mounting a directional hydrophone on a boat and continuously following the tagged individual from the surface for periods up to 96h (2). To enable active tracking without the need for human operators, the authors have demonstrated in previous works that a multi-AUV system using only low resolution angle measurements is able to autonomously track and follow tagged Leopard Sharks (3). A key component of this system is a state-estimator which determines the 2D position of the tagged Shark (4). In order to provide more sensor

  • tracking and following a tagged Leopard Shark with an autonomous underwater vehicle
    Journal of Field Robotics, 2013
    Co-Authors: Christopher M Clark, Dylan Shinzaki, Chris Gage, Christopher G. Lowe, C Forney, E Manii, Michael Farris, Mark A Moline
    Abstract:

    This paper presents a prototype system that enables an autonomous underwater vehicle (AUV) to autonomously track and follow a Shark that has been tagged with an acoustic transmitter. The AUV's onboard processor handles both real-time estimation of the Shark's two-dimensional planar position, velocity, and orientation states, as well as a straightforward control scheme to drive the AUV toward the Shark. The AUV is equipped with a stereo- hydrophone and receiver system that detects acoustic signals transmitted by the acoustic tag. The particular hydrophone system used here provides a measurement of relative bearing angle to the tag, but it does not provide the sign (+ or −) of the bearing angle. Estimation is accomplished using a particle filter that fuses bearing measurements over time to produce a state estimate of the tag location. The particle filter combined with a heuristic-based controller allows the system to overcome the ambiguity in the sign of the bearing angle. The state estimator and control scheme were validated by tracking both a stationary tag and a moving tag with known positions. Offline analysis of these data showed that state estimation can be improved by optimizing diffusion parameters in the prediction step of the filter, and considering signal strength of the acoustic signals in the resampling stage of the filter. These experiments revealed that state estimate errors were on the order of those obtained by current long-distance Shark-tracking methods, i.e., manually driven boat-based tracking systems. Final experiments took place in SeaPlane Lagoon, Los Angeles, where a 1-m Leopard Shark (Triakis semifasciata) was caught, tagged, and released before being autonomously tracked and followed by the proposed AUV system for several hours. C

  • ICRA - A multi-AUV system for cooperative tracking and following of Leopard Sharks
    2013 IEEE International Conference on Robotics and Automation, 2013
    Co-Authors: Dylan Shinzaki, Chris Gage, Sarah Tang, Christopher G. Lowe, Mark A Moline, Barrett W. Wolfe, Christopher M Clark
    Abstract:

    This paper presents a system of multiple coordinating autonomous underwater vehicles (AUV) that can localize and track a Shark tagged with an acoustic transmitter. Each AUV is equipped with a stereo-hydrophone system that provides measurements of the relative bearing to the transmitter, as well as an acoustic modem that allows for inter-AUV communication and hence cooperative Shark state estimation and decentralized tracking control. Online state estimation of the Shark's state is performed using a Particle Filter in which measurements are shared between AUVs. The decentralized control system enables the AUVs to circumnavigate a dynamic target, (i.e. the estimated Shark location). Each AUV circles the target by tracking circles of different radii and at different phase angles with respect to the target so as to obtain simultaneous sensor vantage points and minimize chance of AUV collision. A series of experiments using two AUVs were conducted in Big Fisherman's Cove in Santa Catalina Island, CA and demonstrated the ability to track a tagged Leopard Shark (Triakis semifasciata). The performance of the tracking was compared to standard manual tracking performed using an directional hydrophone operated by a researcher in a boat. In an additional experiment, the AUVs tracked an acoustic tag attached to the tracking boat to quantify the error of the state estimation of the system.