Mapping the Trends of Kawasaki Disease in Hawai'i from 1996 to 2018

Kawasaki disease is a systemic vasculitis of unknown etiology and is the leading cause of acquired heart disease in children in the developed world. Historically, Hawai'i has had the highest incidence of Kawasaki disease in the United States, likely due to the population's unique ancestral composition. To analyze the epidemiology, demographics and spatiotemporal distribution of Kawasaki disease in Hawai'i, a retrospective chart review was conducted utilizing data from Kapi'olani Medical Center for Women and Children encompassing the period of 1996-2018. A total of 858 patients were analyzed with 877 episodes of Kawasaki disease. On average, 37 episodes of Kawasaki disease were diagnosed annually over the 23-year period. The annual incidence was 32 per 100 000 children <5 years of age. Asian children (66.1%) accounted for the majority of cases, followed by Native Hawaiians and Other Pacific Islanders (16.6%). Unlike Japan and the continental United States, there was no characteristic seasonal pattern in the distribution of Kawasaki disease in Hawai'i, which may be attributed to its tropical climate or the recent changes in global weather patterns. Local geographical differences in the incidence of Kawasaki disease demonstrated that the Windward (Eastern) coast of O'ahu had a higher rate, while the Leeward (Western) coast displayed a lower incidence rate. This could be explained by variations in ethnic composition and weather patterns of certain areas. Future studies could provide geographical weather data and statistical analysis to determine what environmental triggers are correlated with Kawasaki disease trends in the State of Hawai'i.

Hypoxia-selective allosteric destabilization of activin receptor-like kinases: A potential therapeutic avenue for prophylaxis of heterotopic ossification

Heterotopic ossification (HO), the pathological extraskeletal formation of bone, can arise from blast injuries, severe burns, orthopedic procedures and gain-of-function mutations in a component of the bone morphogenetic protein (BMP) signaling pathway, the ACVR1/ALK2 receptor serine-threonine (protein) kinase, causative of Fibrodysplasia Ossificans Progressiva (FOP). All three ALKs (-2, -3, -6) that play roles in bone morphogenesis contribute to trauma-induced HO, hence are well-validated pharmacological targets. That said, development of inhibitors, typically competitors of ATP binding, is inherently difficult due to the conserved nature of the active site of the 500+ human protein kinases. Since these enzymes are regulated via inherent plasticity, pharmacological chaperone-like drugs binding to another (allosteric) site could hypothetically modulate kinase conformation and activity. To test for such a mechanism, a surface pocket of ALK2 kinase formed largely by a key allosteric substructure was targeted by supercomputer docking of drug-like compounds from a virtual library. Subsequently, the effects of docked hits were further screened in vitro with purified recombinant kinase protein. A family of compounds with terminal hydrogen-bonding acceptor groups was identified that significantly destabilized the protein, inhibiting activity. Destabilization was pH-dependent, putatively mediated by ionization of a histidine within the allosteric substructure with decreasing pH. In vivo, nonnative proteins are degraded by proteolysis in the proteasome complex, or cellular trashcan, allowing for the emergence of therapeutics that inhibit through degradation of over-active proteins implicated in the pathology of diseases and disorders. Because HO is triggered by soft-tissue trauma and ensuing hypoxia, dependency of ALK destabilization on hypoxic pH imparts selective efficacy on the allosteric inhibitors, providing potential for safe prophylactic use.

Tailoring ultrasound-induced growth of perylene diimide nanowire crystals from solution by modification with poly(3-hexyl thiophene)

Tailoring nanocrystalline morphologies of organic semiconductors holds importance for organic electronics due to the influence of crystal characteristics on optoelectronic properties. Soluble additives that control crystal growth are commonly found in a variety of contexts such as biomineralization, pharmaceutical processing, and food science, while the use of ultrasound to modify crystal nucleation and growth has been routinely employed in producing crystals of food ingredients, biomolecules, pharmaceuticals, and inorganic materials. However, both methods have been applied to the growth of organic semiconductor crystals only in limited fashion. Here, we combine these two approaches to show that colloidally stable nanowire suspensions of a n-type small molecule, perylene diimide (PDI), can be prepared with well-controlled structures by sonocrystallization in the presence of a p-type polymer, poly(3-hexyl thiophene) (P3HT), as a soluble additive. By preferentially adsorbing on lateral crystal faces, P3HT dramatically reduces PDI crystal growth rate in the lateral directions relative to that along the nanowire axis, yielding nanocrystals with widths below 20 nm and narrow width distributions. With the use of uniform short PDI nanowires as seeds and extension with metastable solutions, controlled growth of PDI nanowires by "living crystallization" is demonstrated, providing access to narrowed length distributions and tailored branched crystal morphologies.

Energy and water use by invasive goats (Capra hircus) in an Australian rangeland, and a caution against using broad-scale allometry to predict species-specific requirements

Feral goats (Capra hircus) are ubiquitous across much of Australia's arid and semi-arid rangelands, where they compete with domestic stock, contribute to grazing pressure on fragile ecosystems, and have been implicated in the decline of several native marsupial herbivores. Understanding the success of feral goats in Australia may provide insights into management strategies for this and other invasive herbivores. It has been suggested that frugal use of energy and water contributes to the success of feral goats in Australia, but data on the energy and water use of free-ranging animals are lacking. We measured the field metabolic rate and water turnover rate of pregnant and non-pregnant feral goats in an Australian rangeland during late summer (dry season). Field metabolic rate of pregnant goats (601 ± 37 kJ kg(-0.73)d(-1)) was 1.3 times that of non-pregnant goats (456 ± 24 kJ kg(-0.73)d(-1)). The water turnover rate of pregnant goats (228 ± 18 mL kg(-0.79)d(-1)) was also 1.3 times that of non-pregnant goats (173 ± 18 kg(-0.79)d(-1)), but the difference was not significant (P=0.07). There was no significant difference in estimated dry matter digestibility between pregnant and non-pregnant goats (mean ca. 58%), blood or urine osmolality, or urine electrolyte concentrations, indicating they were probably eating similar diets and were able to maintain osmohomeostasis. Overall, the metabolic and hygric physiology of non-pregnant goats conformed statistically to the predictions for non-marine, non-reproductive placental mammals according to both conventional and phylogenetically independent analyses. That was despite the field metabolic rate and estimated dry matter intake of non-pregnant goats being only 60% of the predicted level. We suggest that general allometric analyses predict the range of adaptive possibilities for mammals, but that specific adaptations, as present in goats, result in ecologically significant departures from the average allometric curve. In the case of goats in the arid Australian rangelands, predictions from the allometric regression would overestimate their grazing pressure by about 40% with implications for the predicted impact on their local ecology.

Fur versus feathers: the different roles of red kangaroo fur and emu feathers in thermoregulation in the Australian arid zone

Fur or feathers provide protection against heat loads from solar radiation for birds and mammals. The red kangaroo (Macropus rufus) and the emu (Dromaius novaehollandiae) are conspicuous in arid environments of Australia where there is potential for high solar loads. The diurnal D. novaehollandiae feeds in the open yet it has a dark coat with a high absorptivity (83%), which contrasts with that of M. rufus (61%), but M. rufus generally shelters in shade during the day. We examined the effect of coat characteristics on the heat load from solar radiation at skin level. Coat depth and density (thermal conductance or insulation) and the level of penetration of solar radiation into the coat were important determinants of solar heat load. For M. rufus less than 25% of incident radiation reached the body at low wind speeds and this diminished to below 15% at moderate wind speeds. In the modest shade M. rufus seeks on summer days, their heat load from solar radiation appears minimal. Colour differences among M. rufus did not affect thermal load. D. novaehollandiae on the other hand is exposed to the full incident solar load in the open but its plumage provides almost complete protection from solar radiation. Solar radiation is absorbed at the feather surface and the insulation provided by the deep coat prevents heat transmission to the skin.

Diets and foraging behaviour of red and eastern grey kangaroos in arid shrub land: is feeding behaviour involved in the range expansion of the eastern grey kangaroo into the arid zone?

Eastern grey kangaroos (Macropus giganteus) have expanded into arid areas usually the habitat of red kangaroos (Macropus rufus). Extra watering sites for domestic stock is the suggested reason. However, changes in vegetation also have occurred due to grazing from domestic stock. We investigated the foraging strategies of M. giganteus and M. rufus in arid rangeland to see if these are involved in the range changes. Foraging patterns were similar, with both species mostly foraging at night; total feeding times were the same. M. giganteus and M. rufus had differing diets, though there was considerable overlap of 81 - 87%. Both species were highly selective, having similar narrow dietary niche breaths. Differences in plant preferences occurred and though both species had a preference for grass that of M. giganteus was higher. A larger foregut in M. giganteus reinforces its focus on grass. M. rufus also selected dicot forbs and malvaceous sub-shrubs. Both kangaroos showed avoidance of abundant chenopod shrubs (saltbushes and bluebushes) and trees. It is likely that the changes to arid-zone vegetation, with a shift to grass and annual dicot forbs, has been important for the expansion of M. giganteus, possibly combined with the greater availability of water.

Is the energetics of mammalian hopping locomotion advantageous in arid environments?

Although hopping is a relatively rare mammalian gait, hopping mammals are common in arid environments. Arid environments are open, with patchy resources, and the widespread use of hopping by arid zone mammals appears to be related to the benefits of fast locomotion. In several species, fast hopping is economical in comparison to fast quadrupedal running. These hopping species can reach greater maximum aerobic speeds than similarly sized runners. Faster locomotion can reduce predation risk and increase opportunities to exploit open microhabitats. More economical locomotion may improve a hopping mammal's ability to adopt alternative foraging strategies. The disadvantages of hopping include an increased cost of slow locomotion, reduced manoeuvrability at slow speeds and reduced ability to exploit densely vegetated patches.

The ecophysiology of survival in juvenile red kangaroos Macropus rufus: greater demands and higher costs

Red kangaroos (Macropus rufus) are large (> 20 kg) herbivorous marsupials common to the arid and semi-arid regions of inland Australia. The population dynamics of M. rufus is tightly linked to environmental factors, which operate partly through the survival of juveniles. A crucial period is the young-at-foot (YAF) stage when juveniles have permanently left the mother?s pouch. YAF and weaned kangaroos have the highest drought-related mortalities of any cohort and show notable differences from adults in their basic physiology. YAF and weaned M. rufus, for example, had a resting metabolic rate (kJ kg-1 d-1) twice that of mature females and 1.5 times that expected for an adult marsupial of equivalent body mass (i.e., kJ kg-0.75 d-1). This greater energy turnover was largely explained by their metabolic demands for growth; juveniles required 70 - 95% of the digestible energy intake (kJ d-1) of mature, non-lactating females. Meeting these costs may not be a problem for juveniles when high-quality, low-fibre forage is available, but they were constrained when only hard-to-digest, high-fibre forage was available. YAF and weaned kangaroos, for example, were unable to sustain growth on forages of more than 40 ? 50% fibre, fibre levels characteristic of forages in arid regions during drought. Yet mature, non-lactating females were capable of maintaining body mass on similar forage. Additionally, juvenile M. rufus required relatively more water than adults for thermoregulation (by up to 2.5-fold), especially under hot conditions, and may need to drink more frequently than adults. Thus, juveniles appear constrained to remain close to water points, increasing their risk of predation and limiting their ability to find the high-quality forage needed for their growth and survival.

Functional capacities of marsupial hearts: size and mitochondrial parameters indicate higher aerobic capabilities than generally seen in placental mammals

This study of marsupial hearts explored the aerobic capacities of this group of mammals; recent information suggests that marsupials possess higher aerobic abilities than previously accepted. Characteristics such as heart mass, mitochondrial features and capillary parameters were examined. A comprehensive study of the heart of red kangaroos was included because of the high maximum oxygen consumption of this species. Goats were also included as a reference placental mammal. Marsupials have a heart that is generally larger than that of placentals. The allometric equation for the relationship between heart mass and body mass for marsupials was M(h)=7.5M(b)(0.944) (M(h) in g and M(b) in kg); the equivalent equation for placental mammals was M(h)=6.0M(b)(0.97). Mitochondrial volume density and inner mitochondrial surface density do not differ between the two mammal groups; although capillary parameters indicated a lower capillary volume in marsupials. Heart size appears to be the major difference between the two groups. The overall pattern seen in marsupials is similar to that of "athletic" placentals and indicates a relatively high aerobic potential.

Energy requirements of the red kangaroo (Macropus rufus): impacts of age, growth and body size in a large desert-dwelling herbivore

Generally, young growing mammals have resting metabolic rates (RMRs) that are proportionally greater than those of adult animals. This is seen in the red kangaroo ( Macropus rufus), a large (>20 kg) herbivorous marsupial common to arid and semi-arid inland Australia. Juvenile red kangaroos have RMRs 1.5-1.6 times those expected for adult marsupials of an equivalent body mass. When fed high-quality chopped lucerne hay, young-at-foot (YAF) kangaroos, which have permanently left the mother's pouch but are still sucking, and recently weaned red kangaroos had digestible energy intakes of 641+/-27 kJ kg(-0.75) day(-1) and 677+/-26 kJ kg(-0.75) day(-1), respectively, significantly higher than the 385+/-37 kJ kg(-0.75) day(-1) ingested by mature, non-lactating females. However, YAF and weaned red kangaroos had maintenance energy requirements (MERs) that were not significantly higher than those of mature, non-lactating females, the values ranging between 384 kJ kg(-0.75) day(-1) and 390 kJ kg(-0.75) day(-1) digestible energy. Importantly, the MER of mature female red kangaroos was 84% of that previously reported for similarly sized, but still growing, male red kangaroos. Growth was the main factor affecting the proportionally higher energy requirements of the juvenile red kangaroos relative to non-reproductive mature females. On a good quality diet, juvenile red kangaroos from permanent pouch exit until shortly after weaning (ca. 220-400 days) had average growth rates of 55 g body mass day(-1). At this level of growth, juveniles had total daily digestible energy requirements (i.e. MER plus growth energy requirements) that were 1.7-1.8 times the MER of mature, non-reproductive females. Our data suggest that the proportionally higher RMR of juvenile red kangaroos is largely explained by the additional energy needed for growth. Energy contents of the tissue gained by the YAF and weaned red kangaroos during growth were estimated to be 5.3 kJ g(-1), within the range found for most young growing mammals.

Locomotion energetics and gait characteristics of a rat-kangaroo, Bettongia penicillata, have some kangaroo-like features

The locomotory characteristics of kangaroos and wallabies are unusual, with both energetic costs and gait parameters differing from those of quadrupedal running mammals. The kangaroos and wallabies have an evolutionary history of only around 5 million years; their closest relatives, the rat-kangaroos, have a fossil record of more than 26 million years. We examined the locomotory characteristics of a rat-kangaroo, Bettongia penicillata. Locomotory energetics and gait parameters were obtained from animals exercising on a motorised treadmill at speeds from 0.6 m s(-1) to 6.2 m s(-1). Aerobic metabolic costs increased as hopping speed increased, but were significantly different from the costs for a running quadruped; at the fastest speed, the cost of hopping was 50% of the cost of running. Therefore B. penicillata can travel much faster than quadrupedal runners at similar levels of aerobic output. The maximum aerobic output of B. penicillata was 17 times its basal metabolism. Increases in speed during hopping were achieved through increases in stride length, with stride frequency remaining constant. We suggest that these unusual locomotory characteristics are a conservative feature among the hopping marsupials, with an evolutionary history of 20-30 million years.

How important is milk for near-weaned red kangaroos ( Macropus rufus) fed different forages?

Red kangaroos (Macropus rufus) are large (>20 kg) herbivorous marsupials common to the arid and semi-arid regions of inland Australia, where drought is frequent. Young-at-foot (YAF) red kangaroos are the age/size class usually most affected by drought. Kangaroos at this YAF stage are making the transition from a milk-based diet to one of herbivory and an inability to adequately digest high-fibre feeds may contribute to their high mortalities during drought. We examined the role of milk in the nutrition of YAF red kangaroos fed forages of different fibre content and evaluated it as an extra energy and/or nitrogen source. Milk intake had little impact on the digestion of herbage by YAF red kangaroos fed low-fibre chopped lucerne (alfalfa) hay. Organic matter (OM) intake was 210+/-20 g day(-1) and 228+/-22 g day(-1), respectively, by YAF fed lucerne and lucerne with milk. Apparent digestibility of lucerne OM was ca. 55%, regardless of milk intake. Fed lucerne, with and without milk, YAF sustained growth rates of ca. 45 g day(-1). Conversely, even with a milk supplement, YAF red kangaroos ingested only 90+/-11 g day(-1) of high-fibre chopped oaten hay, of which they digested only ca. 36%. Despite milk intake, YAF fed chopped oaten hay lost between 0 and 75 g body mass day(-1) and were in negative nitrogen balance (-0.40+/-0.11 g N day(-1)). On all diets nitrogen loss was primarily as endogenous nitrogen (urinary and faecal) rather than as dietary nitrogen. Endogenous nitrogen losses were elevated in YAF fed chopped oaten hay, primarily as non-dietary faecal nitrogen. Overall, when high-quality feed was available, YAF were not markedly dependent on milk. However, YAF fed poor-quality chopped oaten hay would require up to 540 ml day(-1) of late-stage kangaroo milk to attain intakes of energy and nitrogen, and hence growth rates, comparable with those YAF fed lucerne.

Thermoregulation in juvenile red kangaroos (Macropus rufus) after pouch exit: higher metabolism and evaporative water requirements

The population dynamics of red kangaroos (Macropus rufus) in the Australian arid zone is tightly linked with environmental factors, which partly operate via the survival of juvenile animals. A crucial stage is the young-at-foot (YAF) stage when kangaroos permanently exit the pouch. We have examined the thermal biology of YAF red kangaroos during ages from permanent pouch exit until weaning. Over a wide range of environmental temperatures (ambient temperature [T(a)] -5 degrees to 45 degrees C), YAF red kangaroos had a mass-specific metabolism that was generally twice that of adults, considerably higher than would be expected for an adult marsupial of their body size. The total energy requirements of YAF red kangaroos were 60%-70% of those of adult females, which were three times their size. Over the same range in T(a), YAF red kangaroos also had total evaporative water losses equal to those of adult females. At the highest T(a) (45 degrees C), differences were noted in patterns of dry heat loss (dry conductance) between YAF red kangaroos and adult females, which may partially explain the relatively high levels of evaporative cooling by YAF. By weaning age, young kangaroos showed little change in their basal energy and water requirements (at T(a) 25 degrees C) but did show reduced mass-specific costs in terms of energy and water use at extremes of T(a) (-5 degrees and 45 degrees C, respectively). In their arid environment, typified by unpredictable rainfall and extremes of T(a), young red kangaroos may need to remain close to water points, which, in turn, may restrict their ability to find the high-quality forage needed to meet their high energy demands.

Free-ranging heart rate, body temperature and energy metabolism in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus) in the arid regions of South East Australia

Eastern grey kangaroos (Macropus giganteus) are generally regarded as mesic inhabitants. Even though access to drinking water in permanent stock watering troughs is commonly available, these animals are still found in only low densities in arid pastoral areas. We hypothesised that the differential success of red and grey kangaroos in the arid zone may be due to higher energy requirements of M. giganteus with a concomitant need for increased food, rather than limitations imposed by inadequate water access. We set out to test this by indirectly measuring energy expenditure through the monitoring of heart rate by radio telemetry in semi-free-ranging eastern grey and red kangaroos (Macropus rufus). Radio telemetry measurements of heart rate were calibrated against oxygen consumption and were used in the assessment of energy expenditure of animals maintained in an 8-ha enclosure in the arid zone of southeast Australia. Heart rate provided a reliable estimate of oxygen consumption. This well-correlated relationship was curvilinear and was established for each individual. Behavioural observations revealed that both kangaroo species spent most of the day in low energy demanding activities. M. rufus were more active at night whilst M. giganteus were more active in the early mornings and late afternoons. Like other marsupials, both species had low field metabolic rates (FMRs). However, M. giganteus in keeping with their mesic history had higher FMRs than the more arid-adapted M. rufus, particularly during water restriction. Body temperature telemeters revealed a further species difference in that under hot conditions when water is freely available, M. rufus exhibits a higher and more labile daytime body temperature than M. giganteus. During the hottest part of the day M. giganteus maintain body temperature, relying upon increased evaporative cooling mechanisms, such as licking. Indeed, only when access to drinking water was restricted was thermolability evident in M. giganteus. Differences in behaviour and concomitant energy expenditure may thus contribute substantially to the divergent distribution and abundance of these two kangaroo species.

Erythrocyte osmotic fragility of red (Macropus rufus) and grey (Macropus fuliginosus and Macropus giganteus) kangaroos and free-ranging sheep of the arid regions of Australia

The mean corpuscular fragility (MCF) of erythrocytes may reflect phylogenetic characteristics as well as an animal's ability to respond to the osmotic challenges associated with cyclic dehydration and rehydration. This type of ecophysiological stress is commonly encountered by animals living in arid regions and low MCF may contribute to their ability to survive and thrive in these xeric habitats. The eastern grey kangaroo has only in recent times extended its range into the arid zone, and is considered a more mesic inhabitant than the red kangaroo. We therefore compared the ability of eastern grey kangaroos and red kangaroos to handle prolonged periods of water restriction, as well as the MCF of the erythrocytes of free-ranging red, eastern grey and western grey kangaroos found at the Fowlers Gap field station. In addition, the MCF of free-ranging sheep inhabiting the same pastures were used as an experimental control; they are phylogenetically unrelated yet are subjected to the same acclimatisation stresses. While red kangaroos exhibited greater tolerance of dehydration compared to eastern grey kangaroos, the MCF of all three kangaroo species was similar and more resilient to osmotic stresses (MCF, 130 mosmol/kg) than erythrocytes of sheep (MCF, 220 mosmol/kg). The MCF did not change with water restriction, however, the erythrocytes of long-term captive populations fed a comparatively better quality diet were more resistant to osmotic shock than the free-ranging animals. Phylogenetic commonality rather than ecophysiological responses to life in the arid zone appeared to influence MCF. The MCF values of sheep corresponded to that of other ovines; similarly the MCF of kangaroos concurred regardless of their preferred habitats. ecological history and differential success in the arid zone.

Ventilatory accommodation of oxygen demand and respiratory water loss in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus)

We studied ventilation in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus), respectively, within the range of ambient temperatures (T(a)) from -5 degrees to 45 degrees C. At thermoneutral temperatures (Ta=25 degrees C), there were no differences between the species in respiratory frequency, tidal volume, total ventilation, or oxygen extraction. The ventilatory patterns of the kangaroos were markedly different from those predicted from the allometric equation derived for placentals. The kangaroos had low respiratory frequencies and higher tidal volumes, even when adjustment was made for their lower basal metabolism. At Ta>25 degrees C, ventilation was increased in the kangaroos to facilitate respiratory water loss, with percent oxygen extraction being markedly lowered. Ventilation was via the nares; the mouth was closed. Differences in ventilation between the two species occurred at higher temperatures, and at 45 degrees C were associated with differences in respiratory evaporative heat loss, with that of M. giganteus being higher. Panting in kangaroos occurred as a graded increase in respiratory frequency, during which tidal volume was lowered. When panting, the desert red kangaroo had larger tidal volumes and lower respiratory frequencies at equivalent T(a) than the eastern grey kangaroo, which generally inhabits mesic forests. The inference made from this pattern is that the red kangaroo has the potential to increase respiratory evaporative heat loss to a greater level.

Thermoregulation by kangaroos from mesic and arid habitats: influence of temperature on routes of heat loss in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus)

We examined thermoregulation in red kangaroos (Macropus rufus) from deserts and in eastern grey kangaroos (Macropus giganteus) from mesic forests/woodlands. Desert kangaroos have complex evaporative heat loss mechanisms, but the relative importance of these mechanisms is unclear. Little is known of the abilities of grey kangaroos. Our detailed study of these kangaroos' thermoregulatory responses at air temperatures (T(a)) from -5 degrees to 45 degrees C showed that, while some differences occur, their abilities are fundamentally similar. Both species show the basic marsupial characteristics of relatively low basal metabolism and body temperature (T(b)). Within the thermoneutral zone, T(b) was 36.3 degrees + or - 0.1 degrees C (X + or - SE) in both species, and except for a small rise at T(a) 45 degrees C, T(b) was stable over a wide range of T(a). Metabolic heat production was 25% higher in red kangaroos at T(a) -5 degrees C. At the highest T(a) (45 degrees C), both species relied on evaporative heat loss (EHL) to maintain T(b); both panting and licking were used. The eastern grey kangaroo utilised panting (76% of EHL) as the principal mode of EHL, and while this was so for red kangaroos, cutaneous evaporative heat loss (CEHL) was significant (40% of EHL). CEHL appeared to be mainly licking, as evidenced from surface temperatures. Both species utilised peripheral vascular adjustments to control heat flow, as indicated by changes in dry conductance (C(dry)). At lower temperatures, C(dry) was minimal, but it increased significantly at T(a) just below T(b) (33 degrees C); in these conditions, the C(dry) of red kangaroos was significantly higher than that of eastern grey kangaroos, indicating a greater reliance on dry heat loss. Under conditions where heat flows into the body from the environment (T(a) 45 degrees C), there was peripheral vasoconstriction to reduce this inflow; C(dry) decreased significantly from the values seen at 33 degrees C in both kangaroos. The results indicated that, while both species have excellent thermoregulatory abilities, the desert red kangaroos may cope better with more extreme temperatures, given that they respond to T(a) 45 degrees C with lower respiratory evaporation than do the eastern grey kangaroos.

Changes in pattern of heat loss at high ambient temperature caused by water deprivation in a large flightless bird, the emu

When exposed to high ambient temperatures, birds defend body temperature by increasing evaporative water loss, via either respiratory or cutaneous water loss. Water deprivation can lead to changes in thermal responses and lower levels of water use for thermoregulation. We have studied the effect of 2-3 wk of water deprivation on the physiological responses of emus during exposure to an ambient temperature of 45 degrees C. Water deprivation led to a delay in the onset of panting (54 vs. 24 min after start of exposure) and to higher body temperatures (38.7 degrees vs. 38.3 degrees C) at the end of exposure to 45 degrees C. After panting was initiated and body temperature stabilised, the water-deprived emus had a lower total evaporative water loss (77 vs. 101 g/h), the same respiratory water loss (70 vs. 72 g/h), and a lower cutaneous water loss (7 vs. 29 g/h) than they did when hydrated. The factor contributing most to the lower total evaporative water loss in the dehydrated emus was a 47% reduction in dry thermal conductance, which led to a decrease in the exogenous environmental heat load and therefore the level of evaporation needed to defend body temperature. We suggest that the decrease in dry thermal conductance follows from the lower level of cutaneous water loss.

Energetics and biomechanics of locomotion by red kangaroos (Macropus rufus)

As red kangaroos hop faster over level ground, their rate of oxygen consumption (indicating metabolic energy consumption) remains nearly the same. This phenomenon has been attributed to exceptional elastic energy storage and recovery via long compliant tendons in the legs. Alternatively, red kangaroos may have exceptionally efficient muscles. To estimate efficiency, we measured the metabolic cost of uphill hopping, where muscle fibers must perform mechanical work against gravity. We found that uphill hopping was much more expensive than level hopping. The maximal rate of oxygen consumption measured (3 ml O2 kg-1 s-1) exceeds all but a few vertebrate species. However, efficiency values were normal, approximately 30%. At faster level hopping speeds the effective mechanical advantage of the extensor muscles of the ankle joint remained the same. Thus, kangaroos generate the same muscular force at all speeds but do so more rapidly at faster hopping speeds. This contradicts a recent hypothesis for what sets the cost of locomotion. The cost of transport (J kg-1 m-1) decreases at faster hopping speeds, yet red kangaroos prefer to use relatively slow speeds that avoid high levels of tendon stress.

The pattern of respiration with increasing metabolism in a small dasyurid marsupial

Previous studies have indicated that the pattern of respiration in marsupial and placental mammals may be different. Some marsupials have larger tidal volumes and slower respiratory rates under basal conditions. This study examined the respiratory responses of a small marsupial, Dasyuroides byrnei, to increasing metabolic demand. The highest metabolic rate elicited by cold exposure in a helium-oxygen atmosphere was 10.4 times the basal metabolic rate. Basal tidal volumes and respiratory rates were 138% and 46% respectively of the values predicted for placental mammals. The increasing oxygen demands of metabolism were met by increases in ventilation rather than by changes in oxygen extraction. Initially, tidal volume increased until it reached a maximum value 2.6 times that of basal tidal volume. Subsequently, ventilation was augmented by an increase in respiratory frequency. Ventilatory accommodation to an increasing oxygen demand indicated that D. byrnei has an excellent respiratory capacity to deal with the thermogenic demands of a cold environment.

The effects of age, sex, reproductive status and temporal factors on the time-use of free-ranging red kangaroos

The effects of temporal (time of day and season) factors and size, sex, female reproductive state and group size on the diel time-use of free-ranging red kangaroos (Macropus rufus) was examined. Particular emphasis was given to the effects on their foraging behaviour, with foraging divided into cropping, chewing and searching components. The study was conducted in semi-arid western New South Wales from July 1991 to March 1992, a time of deepening drought conditions in New South Wales. Group size had very little influence on the time-use of M. rufus. It was negatively but only weakly correlated with the proportion of foraging time spent chewing (chewing intensity). No significant differences in time-use were found between size classes of adult males (large and medium-sized males), females with or without pouch young, or females with different-sized pouch young (no visible young, small pouch young or large pouch young). Differences occurred between adult males, adult females and subadult kangaroos. These differences were mainly associated with their chewing and searching behaviour and were related to body size; as body size increased the proportion of time spent chewing and the intensity of chewing increased while the proportion of time searching and the proportion of foraging time spent searching (searching intensity) decreased. Neither the proportion of time spent cropping or foraging nor the proportion of foraging time spent cropping (cropping intensity) or the proportion of active time spent foraging (foraging intensity) differed between any size/sex/reproductive class. Temporal effects had a considerable influence on time-use. M. rufus were most active at night and in the few hours after sunrise and sunset. Seasonal changes in time-use were largely a result of changes in daytime behaviour. M. rufus foraged less and rested more during the day in winter than in spring or summer. There was no increase in the intensity or proportion of time spent foraging or cropping at night to compensate for the reduction in diurnal foraging. It is hypothesised that temporal variations in time-use were related to variations in weather and vegetation conditions.

The diet of the Bridled nailtail wallaby (Onychogalea fraenata). II Overlap in dietry niche breadth and plant preferences with the black-striped wallaby (Macropus dorsalis) and domestic cattle

Patterns of dietary selection were examined in the rare bridled nailtail wallaby (Onychogalea fraenata) and compared with those of the black-striped wallaby (Macropus dorsalis) and cattle on the Taunton Scientific Reserve in central Queensland. These two species were considered as possible competitors of 0, fraenata. The dietary niche breadth, the similarity of diet to resources, of 0. fraenata was always narrower than those of the larger species. However, the niche breadths of all species broadened significantly during the driest seasonal conditions, which accounts for the increased dietary overlaps previously reported in these conditions. An analysis of dietary preferences (electivities) showed that 0. fraenata had a high preference for herbaceous plants (forbs and malvaceous species), whereas M. dorsalis and cattle had high preference for grass. During dry conditions the preferred diet of 0. fraenata was considerably different to its actual diet, indicating that the diet was suboptimal. This pattern was not as pronounced in the other herbivores, suggesting that 0. fraenata could be at a competitive disadvantage during these conditions in its last refuge.

The diet of the Bridled nailtail wallaby (Onychogalea fraenata). I Site and seasonal influences and dietry overlap with the black striped wallaby (Macropus dorsalis) and domestic Cattle

The bridled nailtail wallaby (Onychogalea fraenata) is one of Australia's rarest marsupials, persisting only in a small area in central Queensland. Its diet and those of two sympatric herbivores, the blackstriped wallaby (Macropus dorsalis) and domestic cattle (Bos taurus/indicus), were assessed by identifying plant fragments in their faeces. The diet of 0 . fraenata was diverse, consisting of herbaceous plants, grasses and browse. In good seasons the intake was biased towards forbs and other herbaceous plants. Browse was only important when vegetation availability was low. Grass could be a major part of the diet when forbs were scarse. Black-striped wallabies and cattle were largely grass eaters. When conditions were dry, browse contributed up to 16% of the diet of M. dorsalis and 10% of the diet of cattle. Dietary overlap with 0. fraenata was greatest at such times, being above 50% for both species. Potential for dietary competition was apparent and it is suggested that this may have been a factor in the decline of 0 . fraenata with the advancement of European settlement and spread of domestic stock.

Gas exchange in the lung of a dasyurid marsupial: morphometric estimation of diffusion capacity and blood oxygen uptake kinetics

Placental and marsupial mammals differ in the balance of their cardio-respiratory systems. To determine if differences also occur in lung structure, a morphometric study of the lungs of a dasyurid marsupial, Dasyuroides byrnei, was undertaken. The total lung volume was large, but a comparatively smaller proportion was devoted to gas exchange tissue. Eighty-seven percent of lung parenchyma was air space. The volume of capillary blood was lower than would be predicted on a body mass basis, but the hematocrit was high (55%). The rate of oxygen uptake by the blood of D. byrnei was not different from that of recent determinations on human blood. However, a large oxygen capacity resulted in a high theta O2. Morphometric data were used, with theta O2 calculated for D. byrnei, to estimate the pulmonary diffusion capacity. Mass specific DLO2 was high by comparison to those reported for placentals. The erythrocytes contributed 70% of the diffusion resistance to oxygen transfer, with the large theta O2 counteracting the low Vc. We conclude that, similarly to placentals, lung structure is unlikely to limit oxygen transport in this animal, although the structural emphasis appears to be geared towards maximising alveolar ventilation.

Thermogenic capabilities of the opossum Monodelphis domestica when warm and cold acclimated: similarities between American and Australian marsupials

1. Monodelphis domestica is a small marsupial mammal from South America. Its thermogenic abilities in the cold were determined when the opossums were both warm (WA) and cold (CA) acclimated. Maximum heat production of M. domestica was obtained at low temperatures in helium-oxygen. 2. Basal metabolic rate (BMR) in the WA animals was 3.2 W/kg and mean body temperature was 32.6 degrees C at 30 degrees C. These values were lower than those generally reported for marsupials. Nevertheless, these M. domestica showed considerable metabolic expansibility in response to cold. Sustained (summit) metabolism was 8-9 times BMR, while peak metabolism was 11-13 times BMR. These maximum values were equal to, or above, those expected in small placentals. 3. Cold acclimation altered the thermal responses of M. domestica, particularly in warm TaS. However, summit metabolism was not significantly increased; nor did M. domestica show a significant thermogenic response to noradrenaline, which in many small placentals elicits non-shivering thermogenesis. The thermoregulatory responses of this American marsupial were, in most aspects, similar to those of Australian marsupials. This suggests that the considerable thermoregulatory abilities of marsupials are of some antiquity.

Osmotic and ionic regulation during dehydration in a large bird, the emu (Dromaius novaehollandiae): an important role for the cloaca-rectum

The emu, a large (40 kg) flightless bird, has low water requirements yet it has a limited ability to produce concentrated urine. To clarify the factors involved in excretion and water conservation by the emu the patterns of excretion during water restriction were examined. Additionally, kidney function was studied, as also was the role of the cloaca and rectum in the final modification of excreta. Following water restriction the osmolality of the excreta fluid increased to a maximum level at 6 d of 428 +/- 39(8) mosmol (mean +/- S.E.M. (n)), the urine to plasma ratio being 1.35 +/- 0.12(8). In normally hydrated birds almost all Na and Cl were excreted in the fluid fraction but a third of the K was associated with the solid fraction of the excreta. After water restriction for 9 d the pattern of excretion of K did not change but the majority of Na (79%) and Cl (73%) were excreted in the solid phase, possibly associated with urates. In ureteral urine most of the nitrogen was excreted as uric acid or urates; a large fraction, 36 +/- 4(4)%, was not identified. The glomerular filtration rate (G.F.R.) was 41.3 +/- 2.2(6) ml/kg.h. This value is low when compared with other birds and may be related to the large size of the emu. The G.F.R. decreased by 30% after 7 d water restriction. The cloaca-rectum appears to play a major role in the modification of excreta. In vivo perfusion studies showed transepithelial net transport rates of water and major electrolytes to be large. Transport of water from an isosmotic solution, 3.36 +/- 0.17 ml/kg.h, was approximately 10 times the maximum value reported for birds previously. The Na and Cl transport rates were also comparatively high.

Use of helium-oxygen to examine the effect of cold acclimation on the summit metabolism of a marsupial, Dasyuroides byrnei

To determine whether marsupial mammals increase their metabolic capabilities during cold acclimation, the metabolism of both warm and cold acclimated Dasyuroides byrnei was examined by exposure to cold in a helium-oxygen atmosphere. Mean values of heat production and conductance were significantly higher in a helium-oxygen atmosphere than in air. Body temperature did not change until metabolic capacity was exhausted. Both cold and warm acclimated groups could maintain a metabolic scope of 10-11 times the basal or standard level for this species. Such a metabolic scope is much higher than levels recorded for placental mammals. At very low ambient temperatures cold acclimated D. byrnei could sustain a high level of heat production longer than could warm acclimated animals. While there are some similarities between marsupial mammals and placental mammals in their responses to cold acclimation, an increase in maximum metabolism, as reported for placentals, does not seem to occur in marsupials.

In vitro studies of sodium transport across the lower intestine of a desert parrot

The lower intestine (coprodeum and colon) of the Australian parrot, the galah, was mounted in Ussing chambers. Short-circuit current (SCC), electrical potential difference (PD), and unidirectional fluxes of Na and Cl were measured in birds that were fed mixed seeds or were NaCl loaded. The net Na transport of both coprodeum and colon was nearly equal to the SCC, and the flux ratio for Cl was unity. In birds which received mixed seeds, average coprodeal Na transport was 7.8 mu eq . cm-2 . h-1, and PD was 19 mV. The Km for Na was 5.7 meq/l. In colon, Na transport was reduced by 67% and PD by 70%. The ratio between unidirectional Na and Cl fluxes in the serosa-mucosa direction was 0.7. Salt loading suppressed coprodeal, but increased colonic Na transport. The coprodeal and colonic SCC and NA transport of birds receiving mixed seeds were inhibited by amiloride on the mucosal side. Colonic SCC of NaCl-loaded birds was only slightly reduced by amiloride (by 17%), but stimulated by amino acids (by 18%).

Body Temperature Variability in the Australian Water Rat, Hydromys chrysogaster, in Air and Water

Body and skin temperatures were recorded from water rats exposed to a range of air temperatures and also immersed in water at various temperatures. They were able to maintain stable core temperatures (mean 36.1�C, SD 0.65, n=61) at air temperatures up to 30�C. At 35�C they were unable to avoid hyperthermia despite their use of saliva spreading to enhance heat loss. Regional heterothermia was observed both in air and in water, but water rats were unable to maintain deep body temperatures at water temperatures lower than 25�C. Variations in the level of activity in cold water affected the rate of heat loss. Examination of the vascular system revealed the presence of various networks adapted for heat loss, but no major heat-conserving vascular retia. It is suggested that the poor thermoregulatory performance of water rats during aquatic excursions is largely due to the lack of heat-conserving retia, and to the poor insulative capacity of the fur when wet. The platypus, which possesses excellent fur insulation and a highly developed heat-conserving system, is a very competent homeotherm in cold water. The behavioural responses displayed by water rats which enable them to exploit the aquatic environment in south-eastern Australia are discussed.

Standard Metabolism of Monotremes and the Evolution of Homeothermy

The standard metabolic rates (SMR) of species from all extant monotreme genera were determined together with body temperatures. The echidnas, Zaglossus bruijni and Tachyglossus aculeatus, of the Family Tachyglossidae, both had an SMR 25-30% of predicted eutherian levels. The platypus Ornithorhynchus anatinus, however, had a much higher SMR. The weight-independent values (watts, kg*-075) were 0.86, 0.98 and 2.21 respectively for Z. bruijni, T. aculeatus and 0. anatinus. Body temperatures were similar, however, with means in the range 31.3-32�C. The data are suggested to support the idea of a gradual evolution in metabolic capability rather than marked jumps in metabolic levels.

Comparison of the Diets of Yellow-Footed Rock-Wallabies and Sympatric Herbivores in Western New South Wales

Diet of the rare yellow-footed rock wallaby (Petrogale xanthopus) was found by study of faeces along the escarpment of the Coturaundee Range in western New South Wales, Australia. Normally 42 to 52% of the diet (estimated as the occurrence of recognizable particles within a microscope field) was of forbs, mostly small herbaceous ephemeral species. During drought the most important component was browse, 44% of diet. Grass was important. There was considerable overlap of species eaten by the rock wallabies and the introduced goats and rabbits, 75% in the case of goats during drought; rabbits were not seen in the higher parts of the escarpment. There was less competition from the euros (Macropus robustus). Control of introduced herbivores may be essential if the rock wallaby populations are to have a chance of recovery.

Kidney structure and function of desert kangaroos

The structure and function of the kidneys of two species of desert kangaroos, the red kangaroo (Megaleia rufa) and the euro (Macropus robustus), were examined. Both kangaroos had glomerular filtration rates (GFR), renal plasma flows, and urine flow rates, when hydrated and dehydrated, which were lower than those of similarly sized eutherian mammals. The differences observed between the two species of marsupials were both structural and functional. The GFR of the red kangaroo was higher than that of the euro, under hydrated and dehydrated conditions, and this was correlated with the occurrence of larger and more numerous glomeruli, particularly juxtamedullary glomeruli, in the red kangaroo. Although the kidney of the euro had a greater relative medullary thickness than that of the red kangaroo, the latter had better urine-concentrating abilities. As opposed to this the euros reabsorbed significantly more urea from the filtrate when dehydrated (89.0%) than did the red kangaroos (69.2%). This ability of the euro to resorb more urea may be related to their tendency to overgraze their restricted home ranges during drought.

Seasonal Changes in Diet Preferences of Free-Ranging Red Kangaroos, Euros and Sheep in Western New South Wales

Stomach contents of free-ranging animals were analysed botanically for low Atriplex shrubland in western New South Wales, Australia, during 1972-74 in good seasons producing abundant growth and diversity of vegetation. Red kangaroo (Megaleia rufa), euro (Macropus robustus) and sheep (Ovis aries) selected grass and forbs when those were readily available. In poorer pasture sheep selected mainly flat-leaved chenopods (saltbush) and kangaroos selected mainly grass with different amounts of flat- or round-leaved chenopods. Euros were the most selective, eating grass even when there was little grass present. Potential overlaps in diet between kangaroos and sheep were greatest in good pasture and least in the poorest conditions. The other groups of plants considered were non-chenopod shrubs and browse. Extent of overlap was not clear, because animals may have eaten different species within the groups of plants. The study period did not include any severe drought, in which overlap in diet and competition between animal species would have been most significant.

Effects of dehydration on body-water distribution in desert kangaroos

The effect of dehydration on the distribution of water in the bodies of two species of desert kangaroos, the red kangaroo Megaleia rufa and the euro Macropus robustus, has been examined. The volumes of various body-fluid compartments were determined in normally hydrated animals and then after the kangaroos had been dehydrated until body weight declined to 80% of the initial weight. The fluid compartments examined were total body water, plasma volume, intracellular volume (cellular and gut water), and extracellular volume. Both species were camel-like in their response to dehydration in that plasma volume was maintained in both species, falling by only 8.3% in red kangaroos and 7.4% in euros. The pattern of water loss from other compartments differed between species, particularly gut water loss. This compartment, which includes the large rumenlike fore stomach, contributed 56% of the total water loss of red kangaroos but only 22% of the loss from euros. The ecological implications of the preferential maintenance of gut water by the sedentary, cave-dwelling euros have been discussed.

Comparative metabolism of tritiated water by macropodid marsupials

The total body-water content (TBW) and rate of water turnover were measured usingtritiated water in five species of macropodod marsupials (kangaroos), which ranged in weight from 1 to 50 kg. Animals fitted with rumen cannulas were used to estimate the time required for tritiated water to equilibrate within the body of large kangaroos. In hydrated kangaroos this was 6 h, during the time 2.7% of the injected tritiated waterwas lost from the body. During dehydration, the equilibrium time was extended to 10h. Values up to 78% of body weight were found for TBW in the larger species of kangaroo, and these values were similiar to those found for other ruminantlike mammals, particularly those with a low body-fat content. The smaller macropodids had a TBW (about 60% of body weight) similiar to that of most laboratory mammals. The rates of waterturnover of the macropodids were related to body weights by the expression 1/day = 0.09kg-0.80. Macropodid marsupials have a daily water usage shich is about two-thirds ofthat found for eitherians and this may be related to the lower metabolic rate of marsupials.

Role of the sweating from the tail in the thermal balance of the rat-kangaroo Potorous tridactylus

Among the marsupials the thermoregulatory response of sweating is uncommon and has only been described in the larger macropodids. Sweating in kangaroos is very unusual in that it only occurs in response to an exercise heat load. The thermoregulatory responses of a smaller, more generalized rat-kangaroo Potorous tridactylus were therefore examined to obtain a more general appreciation of sweating in macropodids. The pattern of heat balance at low and neutral temperatures was characteristic of that previously found for macropodids; body temperature was 35.9 � 0.52 (mean � se). Standard metabolism was only slightly higher than the predicted level for marsupials and minimal conductance was low, c. 1.3 W m-2 per degree Celsius. At moderate air temperatures heat was primarily lost by vasodilation and panting. The thermoregulatory responses at high air temperatures (near or above body temperature) also included copious sweating from the tail, but not from the body generally. Sweating rates of 600-650 g water per m2 per hour were obtained; these are about twice the generally reported rates for eutherians such as cows and horses.

Likely effects of standing and lying on the radiating heat load experienced by a resting kangaroo on a summer day

A study was carried out to examine the effect of posture (standing or lying) on the radiation heat load which would be experienced by a kangaroo resting under a small desert tree during a summer day. Measurements were made to assess the temperature and radiation characteristics in three situations judged to be equivalent to the following: (1) a kangaroo standing in the sun in open country; (2) an animal standing in the shade of a small tree; (3) an animal lying in the same shade. The overall pattern of results was shown by the effective radiation temperature measurements made at midday: 78.3, 57.6, and 52.5C for positions (I), (2), and (3) respectively. The relative contributions of solar and long-wave infrared radiation to the pattern of results are discussed.

Seasonal variation in the plasma and the urine electrolyte concentration of the arid zone kangaroos Megaleia rufa and the Macropus robustus

The seasonal variation in the plasma and urine electrolyte concentration and osmolality of the arid zone kangaroos Megaleia rufa (red kangaroo) and Macropus robustus (euro) has been examined. The urine osmolality of both species appeared to be influenced by environmental temperatures and also the status of feed. The osmolality of urine from red kangaroos was generally higher than that from euros. However, the relative medullary thickness of euro kidneys was greater than that of red kangaroo kidneys, indicating that euros may have the greater urine-concentrating capability. The pattern of sodium and potassium excretion indicated that species of Atriplex (saltbush) and Kochia (bluebush), which are high in sodium relative to potassium, may comprise a major part of the diet of the red kangaroo and euro in western New South Wales.