The high aerobic capacity of a small, marsupial rat-kangaroo (<i>Bettongia penicillata</i>) is matched by the mitochondrial and capillary morphology of its skeletal muscles

Webster, Koa N.; Dawson, Terence J.

doi:10.1242/jeb.071365

Cited by 3 publications

(15 citation statements)

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“…) is, as initially proposed (Hoppeler and Lindstedt, 1985), consistent in placentals (Weibel et al, 2004) and macropodiform marsupials (Webster and Dawson, 2012).…”

Section: Introductionsupporting

confidence: 86%

“…The generality of this assertion is not certain because, while Hinds and colleagues (Hinds et al, 1993) measured comparatively high fAS during locomotion for several smaller species of marsupial, their reported MMR values did not reach 'athletic' placental levels. However, the MMR value obtained (Hinds et al, 1993) for B. penicillata was lower than those obtained on more extensively trained animals Webster and Dawson, 2012). The only other marsupial for which comparable data are available is a South American opossum, Monodelphis domestica (Family: Didephidae) (M b ≈90g).…”

Section: Introductionmentioning

confidence: 81%

“…To assess the muscle mitochondrial parameters of the skeletal muscle of the whole body, we followed a sampling procedure comparable to that developed previously (Hoppeler et al, 1984) and used in other studies of marsupials (Dawson et al, 2004;Webster and Dawson, 2012). The musculature of S. crassicaudata was divided into five functional regions, these being head/neck, foreleg, trunk, hindleg and tail.…”

Section: Muscle Sample Collection and Preparationmentioning

confidence: 99%

“…Underlying this capability in M. rufus is a large mass of locomotor muscles that have comparatively high mitochondrial and capillary volumes (Dawson et al, 2004). Another hopping marsupial, Bettongia penicillata, a rat-kangaroo (Family Potoroidae), though much smaller (body mass, M b , 1kg), also shows an elevated fAS of 23 and a markedly high MMR Webster and Dawson, 2012). Again, this is associated with a large skeletal muscle mass that has relatively high muscle mitochondrial volume densities and both a large total capillary volume and a large total capillary erythrocyte volume (Webster and Dawson, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Another hopping marsupial, Bettongia penicillata, a rat-kangaroo (Family Potoroidae), though much smaller (body mass, M b , 1kg), also shows an elevated fAS of 23 and a markedly high MMR Webster and Dawson, 2012). Again, this is associated with a large skeletal muscle mass that has relatively high muscle mitochondrial volume densities and both a large total capillary volume and a large total capillary erythrocyte volume (Webster and Dawson, 2012). Overall, the muscle and cardio-respiratory structural features of M. rufus and B. penicillata are identical to those previously reported for 'athletic' placental mammals of equivalent sizes (Weibel et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Muscle mitochondrial volume and aerobic capacity in a small marsupial (Sminthopsis crassicaudata) match those of 'athletic' placentals, reflecting flexible links between energy-use levels in mammals generally.

Dawson

Webster

Lee

et al. 2012

Journal of Experimental Biology

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SUMMARYWe investigated the muscle structure-function relationships that underlie the aerobic capacity of an insectivorous, small (~15g) marsupial, Sminthopsis crassicaudata (Family: Dasyuridae), to obtain further insight into energy use patterns in marsupials relative to those in placentals, their sister clade within the Theria (advanced mammals). Disparate hopping marsupials (Suborder Macropodiformes), a kangaroo (Macropus rufus) and a rat-kangaroo (Bettongia penicillata), show aerobic capabilities as high as those of ʻathleticʼ placentals. Equivalent muscle mitochondrial volumes and cardiovascular features support these capabilities. We examined S. crassicaudata to determine whether highly developed aerobic capabilities occur elsewhere in marsupials, rather than being restricted to the more recently evolved Macropodiformes. This was the case. Treadmill-trained S. crassicaudata . Hopping marsupials have comparable aerobic levels when body mass variation is considered. Sminthopsis crassicaudata has a basal metabolic rate (BMR) about 75% of placental values but it has a notably large factorial aerobic scope (fAS) of 13; elevated fAS also features in hopping marsupials. The V O2,max of S. crassicaudata was supported by an elevated total muscle mitochondrial volume, which was largely achieved through high muscle mitochondrial volume densities, Vv(mt,f), the mean value being 14.0±1.33%. These data were considered in relation to energy use levels in mammals, particularly field metabolic rate (FMR). BMR is consistently lower in marsupials, but this is balanced by a high fAS, such that marsupial MMR matches that of placentals. However, FMR shows different mass relationships in the two clades, with the FMR of small (<125g) marsupials, such as S. crassicaudata, being higher than that in comparably sized placentals, with the reverse applying for larger marsupials. The flexibility of energy output in marsupials provides explanations for this pattern. Overall, our data refute widely held notions of mechanistically closely linked relationships between body mass, BMR, FMR and MMR in mammals generally.

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“…) is, as initially proposed (Hoppeler and Lindstedt, 1985), consistent in placentals (Weibel et al, 2004) and macropodiform marsupials (Webster and Dawson, 2012).…”

Section: Introductionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 81%

Section: Muscle Sample Collection and Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Muscle mitochondrial volume and aerobic capacity in a small marsupial (Sminthopsis crassicaudata) match those of 'athletic' placentals, reflecting flexible links between energy-use levels in mammals generally.

Dawson

Webster

Lee

et al. 2012

Journal of Experimental Biology

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Understanding Australia’s unique hopping species: a comparative review of the musculoskeletal system and locomotor biomechanics in Macropodoidea

et al. 2022

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Kangaroos and other macropodoids stand out among mammals for their unusual hopping locomotion and body shape. This review examines the scaling of hind- and forelimb bones, and the primary ankle extensor muscles and tendons. We find that the scaling of the musculoskeletal system is sensitive to the phylogenetic context. Tibia length increases with positive allometry among most macropodoids, but negative allometry in eastern grey kangaroos and isometry in red kangaroos. Femur length decreases with stronger negative allometry in eastern grey and red kangaroos than among other macropodoids. Muscle masses scale with negative allometry in western grey kangaroos and with isometry in red kangaroos, compared to positive allometry in other macropodoids. We further summarise the work on the hopping gait, energetics in macropodoids, and stresses in the musculoskeletal system in an evolutionary context, to determine what trade-offs may limit locomotor performance in macropodoids. When large kangaroos hop, they do not increase oxygen consumption with speed, unlike most mammals, including small hopping species. We conclude that there is not enough information to isolate the biomechanical factors that make large kangaroos so energy efficient. We identify key areas for further research to fill these gaps.

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Influence of the Environment on Body Temperature of Racing Greyhounds

2016

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Heat strain is a potential risk factor for racing greyhounds in hot climates. However, there have been limited studies into the incidence of heat strain (when excess heat causes physiological or pathological effects) in racing greyhounds. The aim of this study was to determine if heat strain occurs in racing greyhounds, and, if so, whether environmental factors (e.g., ambient temperature and relative humidity) or dog-related factors (e.g., sex, bodyweight, color) are associated with the risk of heat strain. A total of 229 greyhounds were included in over 46 race meetings and seven different race venues in South Australia, Australia. Rectal temperatures of dogs were measured pre- and postrace and urine samples collected for analysis of myoglobinuria. Ambient temperature at race times ranged between 11.0 and 40.8°C and relative humidity ranged from 17 to 92%. There was a mean increase in greyhound rectal temperature of 2.1°C (range 1.1–3.1°C). A small but significant association was present between ambient temperature and increase in rectal temperature (r2 = 0.033, P = 0.007). The mean ambient temperature at race time, of dogs with postrace rectal temperature of or exceeding 41.5°C, was significantly greater than at race time of dogs with a postrace rectal temperature ≤41.5°C (31.2 vs. 27.3°C, respectively, P = 0.004). When the ambient temperature reached 38oC, over one-third (39%) of dogs had a rectal temperature >41.5°C. Over half of postrace urine samples were positive by Dipstick reading for hemoglobin/myoglobin, and of 77 urine samples positive for Dipstick readings, 95% were positive for myoglobin. However, urinary myoglobin levels were not associated with ambient temperature or postrace rectal temperatures. The mean increase in rectal temperature was greater in dark (black, blue, brindle) than light (fawn and white) colored greyhounds. The results suggest heat strain occurs in racing greyhounds, evidenced by postrace rectal temperatures over 41.5°C and postrace myoglobinuria. Risk of heat strain may be increased in higher ambient temperatures and in darker colored greyhounds. Further research into the incidence of heat strain in racing greyhounds, and longer term physiological responses to heat strain, are warranted.

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The high aerobic capacity of a small, marsupial rat-kangaroo (Bettongia penicillata) is matched by the mitochondrial and capillary morphology of its skeletal muscles

Cited by 3 publications

References 42 publications

Muscle mitochondrial volume and aerobic capacity in a small marsupial (Sminthopsis crassicaudata) match those of 'athletic' placentals, reflecting flexible links between energy-use levels in mammals generally.

Muscle mitochondrial volume and aerobic capacity in a small marsupial (Sminthopsis crassicaudata) match those of 'athletic' placentals, reflecting flexible links between energy-use levels in mammals generally.

Understanding Australia’s unique hopping species: a comparative review of the musculoskeletal system and locomotor biomechanics in Macropodoidea

Influence of the Environment on Body Temperature of Racing Greyhounds

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