A comparison of lactate dehydrogenase from an ectothermic and an endothermic animal.

Adaptation to environmental temperature is examined in beef heart, beef muscle, and flounder muscle lactate dehydrogenases (EC 1.1.1.27). Low temperature adaptation in the ectothermic (flounder) enzyme is indicated by a reduced enthalpy of activation for kcat (enzyme turnover number, s-1) and increased catalytic efficiency. Also, the reaction rate at low substrate concentrations has a maximum at a lower temperature than in the endothermic enzymes. This is a result of altered bonding in the enzyme-substrate complexes. Adaptation to higher temperatures in the endothermic (beef) enzymes is suggested by a decreased sensitivity to heat denaturation, especially in the presence of substrates. A direct correlation is found between the degree of bonding in the enzyme-substrate complexes and the decrease in rate of heat denaturation caused by addition of substrates.     

Seasonality determines patterns of growth and age structure over a geographic gradient in an ectothermic vertebrate

Environmental variation connected with seasonality is likely to affect the evolution of life-history strategies in ectotherms, but there is no consensus as to how important life-history traits like body size are influenced by environmental variation along seasonal gradients. We compared adult body size, skeletal growth, mean age, age at first reproduction and longevity among 11 common frog (Rana temporaria) populations sampled along a 1,600-km-long latitudinal gradient across Scandinavia. Mean age, age at first reproduction and longevity increased linearly with decreasing growth season length. Lifetime activity (i.e. the estimated number of active days during life-time) was highest at mid-latitudes and females had on average more active days throughout their lives than males. Variation in body size was due to differences in lifetime activity among populations??individuals (especially females) were largest where they had the longest cumulative activity period??as well as to differences between populations in skeletal growth rate as determined by skeletochronological analyses. Especially, males grew faster at intermediate latitudes. While life-history trait variation was strongly associated with latitude, the direction and shape of these relationships were sex- and trait-specific. These context-dependent relationships may be the result of life-history trade-offs enforced by differences in future reproductive opportunities and time constraints among the populations. Thus, seasonality appears to be an important environmental factor shaping life-history trait variation in common frogs.     

Identification and characterization of a FcR homolog in an ectothermic vertebrate, the channel catfish (Ictalurus punctatus)

An FcR homolog (IpFcRI), representing the first such receptor from an ectothermic vertebrate, has been identified in the channel catfish (Ictalurus punctatus). Mining of the catfish expressed sequence tag databases using mammalian FcR sequences for CD16, CD32, and CD64 resulted in the identification of a teleost Ig-binding receptor. IpFcRI is encoded by a single-copy gene containing three Ig C2-like domains, but lacking a transmembrane segment and cytoplasmic tail. The encoded Ig domains of IpFcRI are phylogenetically and structurally related to mammalian FcR and the presence of a putative Fc-binding region appears to be conserved. IpFcRI-related genomic sequences are also present in both pufferfish and rainbow trout, indicating the likely presence of a soluble FcR in other fish species. Northern blot and qualitative PCR analyses demonstrated that IpFcRI is primarily expressed in IgM-negative leukocytes derived from the lymphoid kidney tissues and PBL. Significantly lower levels of IpFcRI expression were detected in catfish clonal leukocyte cell lines. Using the native leader, IpFcRI was secreted when transfected into insect cells and importantly the native IpFcRI glycoprotein was detected in catfish plasma using a polyclonal Ab. Recombinant IpFcRI binds catfish IgM as assessed by both coimmunoprecipation and cell transfection studies and it is presumed that it functions as a secreted FcR akin to the soluble FcR found in mammals. The identification of an FcR homolog in an ectothermic vertebrate is an important first step toward understanding the evolutionary history and functional importance of vertebrate Ig-binding receptors.     

Pendular mechanics and the kinematics and energetics of brachiating locomotion

Because brachiating locomotion is characterized by a pattern of swinging movements, brachiation has often been analogized to pendular motion, and aspects of the mechanics of pendular systems have been used to provide insight into both energetic and structural design aspects of this locomotor mode. However, there are several limitations to this approach. First, the motions of brachiating animals only approximate pendular motion, and therefore the energetics of these two systems are only roughly comparable. Second, the kinematic similarity between brachiation and pendular motion will be maximal at only one velocity, and the correspondence will be even less at greater or lesser speeds. Third, all forms of terrestrial locomotion that involve the use of limbs incorporate elements of pendular systems, and therefore brachiation is not unusual in this respect. Finally, it has been suggested that the mechanics of pendular motion will constrain the maximum attainable body size of brachiating animals and that this mechanical situation explains the lack of brachiating primates of greater than 30-kg body size; the present analysis provides evidence that the constraints on body size are far less strict than previously indicated and that extrinsic factors such as the geometry of the forest environment are more likely to dictate maximum body size for brachiators.     

Locomotor energetics in primates: gait mechanics and their relationship to the energetics of vertical and horizontal locomotion

All primates regularly move within three-dimensional arboreal environments and must often climb, but little is known about the energetic costs of this critical activity. Limited previous work on the energetics of incline locomotion suggests that there may be differential selective pressures for large compared to small primates in choosing to exploit a complex arboreal environment. Necessary metabolic and gait data have never been collected to examine this possibility and biomechanical mechanisms that might explain size-based differences in the cost of arboreal movement. Energetics and kinematics were collected for five species of primate during climbing and horizontal locomotion. Subjects moved on a treadmill with a narrow vertical substrate and one with a narrow horizontal substrate at their maximum sustainable speed for 10–20 min while oxygen consumption was monitored. Data during climbing were compared to those during horizontal locomotion and across size. Results show that climbing energetic costs were similar to horizontal costs for small primates (<0.5 kg) but were nearly double for larger species. Spatio-temporal gait characteristics suggest that the relationship between the cost of locomotion and the rate of force production changes between the two locomotor modes. Thus, the main determinants of climbing costs are fundamentally different from those during horizontal locomotion. These new results combining spatiotemporal and energetic data confirm and expand on our previous argument (Hanna et al.: Science 320 (2008) 898) that similar costs of horizontal and vertical locomotion in small primates facilitated the successful occupation of a fine-branch arboreal milieu by the earliest primates.     

Early Miocene gastropod and ectothermic vertebrate remains from the Lesvos Petrified Forest (Greece)

The Lesvos Petrified Forest (western Lesvos, Greece) has long been famous for its plant fossils. Recently, one proboscidean (from the Gavathas locality) and seven micromammalian species (from the Lapsarna locality) were described; these were the first animals to be found in the Early Miocene subtropical forest. For the first time, a fauna of gastropods and ectothermic vertebrates from the Lapsarna locality is now available. This fauna derives from lacustrine sediments under the pyroclastic material that contains the petrified plants. Based on fragmented mollusc remains, isolated fish pharyngeal teeth and utricular otoliths (lapilli), fragmented amphibian vertebrae and a tooth-bearing element, and reptile fragmented dentaries, teeth, osteoderms and vertebrae, the presence of eight freshwater and three terrestrial gastropod species, three freshwater cyprinid species, and two amphibian and five reptile taxa has been confirmed. Stratigraphical and radiometric data suggest an age older than 18.4 ± 0.5 Ma (latest Early Miocene), in good agreement with the faunal composition. This paper is the first report of the concurrent presence of three cyprinid fish species in a Greek Early Miocene locality, as well as the first documentation of an Early Miocene proteid amphibian in southeastern Europe. The present findings represent one of the best-documented Early Miocene gastropod and fish faunas in the Aegean/southern Balkans, thus adding to our knowledge of Early Miocene amphibians and reptiles from that region and providing valuable information on the local subtropical ecosystem.     

The contribution of contemporary climate to ectothermic and endothermic vertebrate distributions in a glacial refuge

Aim Climatic factors are known to influence species distributions. However, elucidating the underlying mechanisms is challenging because direct and indirect effects of climatic and non‐climatic factors are correlated. In the absence of this covariation and at fine‐grain resolutions the direct effect of climate via physiological constraints should be stronger on the distributions of ectothermic organisms. So far, no comprehensive study has explicitly tested the influence of climate on species distributions by quantitatively comparing ectothermic and endothermic vertebrates. Location Peninsular Spain. Methods Presence–absence data of native terrestrial vertebrates in Peninsular Spain were modelled using generalized additive models to disentangle the influence of climate and other contemporary correlated factors (topography and plant cover). We performed partial regressions to partition the deviance explained by climatic and non‐climatic effects into independent and shared components. We compared the independent contributions of climatic and non‐climatic effects between ectothermic and endothermic vertebrates, and among mammals, birds, reptiles and amphibians. Results After reducing the covariation with non‐climatic factors, climate explained a greater proportion of deviance in ectotherms than in endotherms. Also, the contribution of temperature was highest for reptiles, and the contribution of precipitation was highest for amphibians, after extracting their overlaps with precipitation and temperature, respectively. The contribution of topography and plant cover remained high for birds after extracting the overlap with climate. Main conclusions Our results are consistent with the prediction that, at fine resolutions, the direct influence of climate (via physiological constraints) on range distributions is stronger in ectothermic vertebrates. Also, at least for birds, indirect effects of climate (via plant productivity) and other habitat characteristics remained relatively important once their covariation with climate was reduced. This study shows that controlling the direct effects of climate by their indirect effects and/or other correlated factors, combined with comparisons among functional groups, can be a useful approach to elucidate causal links with the spatial patterns of organisms.     

Limb morphology,bipedal gait,and the energetics of hominid locomotion

How viable is the argument that increased locomotor efficiency was an important agent in the origin of hominid bipedalism? This study reviews data from the literature on the cost of human bipedal walking and running and compares it to data on quadrupedal mammals including several non-human primate species. Literature data comparing the cost of bipedal and quadrupedal locomotion in trained capuchin monkeys and chimpanzees are also considered. It is concluded that increased energetic efficiency would not have accrued to early bipeds. Presumably, however, selection for improved efficiency in the bipedal stance would have occurred once the transition was made. Would such a process have included selection for increased limb length? Data on the cost of locomotion vs. limb length reveal no significant relationship between these variables in 21 species of mammals or in human walking or running. © 1996 Wiley-Liss, Inc.     

A comparison of potato and vertebrate lactate dehydrogenases.

The incorporation of labelled leucine was measured in protein fractions of muscle in intact control and dystrophic female hamsters and also in cell-free preparations obtained from these animals. The labelling of the soluble sarcoplasmic protein fraction, the microsomal protein fraction and the sarcolemma protein fraction was increased in the dystrophic hindleg muscle. The specific radioactivities of the sarcolemma protein fraction and other fractions were increased markedly relative to that of free leucine in the dystrophic muscle. In cell-free preparations where ribonuclease effects were avoided, the dystrophic muscle exhibited an increased synthesis of peptide bonds.     

Discontinuous ventilation and energetics of locomotion in the desert-dwelling female mutillid wasp, Dasymutilla gloriosa

Abstract. Data on the discontinuous ventilation cycle and cost of pedestrian locomotion in female Dasymutilla gloriosa (Sauss.), a desert-dwelling mutillid, are described and compared with equivalent data from other Hymenoptera. The discontinuous ventilation cycle was intermediate between that found in xeric and mesic hymenopterans, with the open phase being about 20% of the cycle. No noticeable flutter phase was observed. Thus D. gloriosa does not attempt to reduce respiratory water loss to the same extent as found in other desert dwelling Hymenoptera. The minimum cost of transport was significantly higher than that obtained for several ant species, indicating that ants are probably more efficient runners than any other Hymenoptera.     

A brief history of vertebrate functional morphology

The discipline of functional morphology grew out of a comparativeanatomical tradition, its transformation into a modern experimentalscience facilitated largely by technological advances. Earlymorphologists, such as Cuvier, felt that function was predictablefrom organismal form, to the extent that animals and plantsrepresented perfect adaptations to their habits. However, anatomyalone could not reveal how organisms actually performed theiractivities. Recording techniques capable of capturing fast motionwere first required to begin to understand animal movement.Muybridge is most famous for his pioneering work in fast photographyin the late 19th century, enabling him to "freeze" images ofeven the fastest horse at a full gallop. In fact, contemporarykinematic analysis grew directly out of the techniques Muybridgedeveloped. Marey made perhaps an even greater contribution toexperimental science through his invention of automatic apparatifor recording events of animal motion. Over the first half ofthe 20th century, scientists developed practical methods torecord activity patterns from muscles of a living, behavinghuman or animal. The technique of electromyography, initiallyused in clinical applications, was co-opted as a tool of organismalbiologists in the late 1960s. Comparative anatomy, kinematicanalysis and electromyography have for many years been the mainstayof vertebrate functional morphology; however, those interestedin animal form and function have recently begun branching outto incorporate approaches from experimental biomechanics andother disciplines (see accompanying symposium papers), and functionalmorphology now stands at the threshold of becoming a truly integrative,central field in organismal biology.     

The oxaloacetate reductase activity of vertebrate lactate dehydrogenase

• 1.1. Lactate dehydrogenase is able to catalyse the reduction of oxaloacetate utilizing NADH as coenzyme but, contrary to a previous report, with greatly reduced values for both K_m and V_max when compared to the normal substrate pyruvate.
• 2.2. A modification to the published procedure for the purification of vertebrate l-lactate dehydrogenase by affinity chromatography on oxamated Sepharose is described.
• 3.3. Supernatant malate dehydrogenase does not catalyse the reduction of pyruvate at rates greater than 1%, of the rates with oxaloacetate.

     

The responses of the catecholamines and beta-endorphin to brief maximal exercise in man

The responses to brief maximal exercise of 10 male subjects have been studied. During 30 s of exercise on a non-motorized treadmill, the mean power output (mean +/- SD) was 424.8 +/- 41.9 W, peak power 653.3 +/- 103.0 W and the distance covered was 167.3 +/- 9.7 m. In response to the exercise blood lactate concentrations increased from 0.60 +/- 0.26 to 13.46 +/- 1.71 mmol.l-1 (p less than 0.001) and blood glucose concentrations from 4.25 +/- 0.45 to 5.59 +/- 0.67 mmol.l-1 (p less than 0.001). The severe nature of the exercise is indicated by the fall in blood pH from 7.38 +/- 0.02 to 7.16 +/- 0.07 (p less than 0.001) and the estimated decrease in plasma volume of 11.5 +/- 3.4% (p less than 0.001). The plasma catecholamine concentrations increased from 2.2 +/- 0.6 to 13.4 +/- 6.4 nmol.l-1 (p less than 0.001) and 0.2 +/- 0.2 to 1.4 +/- 0.6 nmol.l-1 (p less than 0.001) for noradrenaline (NA) and adrenaline (AD) respectively. The plasma concentration of the opioid beta-endorphin increased in response to the exercise from less than 5.0 to 10.2 +/- 3.9 p mol.l-1. The post-exercise AD concentrations correlated with those for lactate as well as with changes in pH and the decrease in plasma volume. Post-exercise beta-endorphin levels correlated with the peak speed attained during the sprint and the subjects peak power to weight ratio. These results suggest that the increases in plasma adrenaline are related to those factors that reflect the stress of the exercise and the contribution of anaerobic metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of plasma catecholamines on the lactate threshold during graded exercise

This investigation examined the relationship among plasma catecholamines, the blood lactate threshold (TLa), and the ventilatory threshold (TVE) in highly trained endurance athletes. Six competitive cyclists and six varsity cross-country runners performed a graded exercise test via two different modalities: treadmill running and bicycle ergometry. Although maximal oxygen consumption (VO2 max) did not differ significantly for the cyclists for treadmill running and cycling (64.6 +/- 1.0 and 63.5 +/- 0.4 ml O2.kg-1-min-1, respectively), both TLa and TVE occurred at a relatively earlier work load during the treadmill run. The opposite was true for the runners as TLa and TVE appeared at an earlier percent of VO2max during cycling compared with treadmill running (60.0 +/- 1.7 vs. 75.0 +/- 4.0%, respectively, TLa). The inflection in plasma epinephrine shifted in an identical manner and occurred simultaneously with that of TLa (r = 0.97) regardless of the testing protocol or training status. Although a high correlation (r = 0.86) existed for the shift in TVE and TLa, this relationship was not as strong as was seen with plasma epinephrine. The results suggest that a causal relationship existed between the inflection in plasma epinephrine and TLa during a graded exercise test. This association was not as strong for TVE and TLa.     

The trade-off between fleeing and tonic immobility behaviors in an ectothermic animal

acta ethologica - When a prey is perceived and attacked, it may adopt direct anti-predator strategies, such as fleeing and tonic immobility (TI). During this latter, individuals remain in a...     

Temperature and hypoxia in ectothermic tetrapods

 

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Interactions between temperature and hypoxia in ectothermic tetrapods (reptiles and amphibians) are reviewed.