Basic concepts relevant to heat transfer in fishes,and their use in measuring the physiological thermoregulatory abilities of tunas

Synopsis Aerobic heat production and heat loss via the gills are inexorably linked in all water breathing teleosts except tunas. These processes are decoupled in tunas by the presence of vascular counter-current heat exchangers, and sustained (i.e., steady state) muscle temperatures may exceed water temperature by 10° C or more in larger individuals. The presence of vascular counter-current heat exchangers is not clearly advantageous in all situations, however. Mathematical models predict that tunas could overheat during strenuous activity unless the efficacy of vascular heat exchangers can be reduced, and that they may be activity limited in warmer waters. Tunas may likewise be forced out of potentially usable habitats as they grow because they have to occupy cooler waters. Vascular counter-current heat exchangers also slow rates of heating and cooling. A reduced rate of muscle temperature decrease is clearly advantageous when diving into colder water to chase prey or avoid predators. A reduced rate of heat gain from the environment would be disadvantageous, however, when fish return to the warmer surface waters. When subjected to changes in ambient temperature, tunas cannot defend a specific body temperature and do not thermoregulate in the mammalian sense. Yet when appropriately analyzed, data taken under steady state and non-steady state conditions indicate that tunas are not strictly prisoners of their own thermoconserving mechanisms. They apparently can modify overall efficiency of their vascular counter-current heat exchangers and thus avoid overheating during bouts of strenuous activity, retard cooling after diving into colder water, and rapidly warm their muscles after voluntarily entering warmer water. The exact physiological mechanisms employed remain to be elucidated.Paper from the International Union of Biological Societies symposium The biology of tunas and billfishes: an examination of life on the knife edge, organized by Richard W. Brill and Kim N. Holland.     

Muscle metabolic profile and oxygen transport capacity as determinants of aerobic and anaerobic thresholds

Aerobic and anaerobic thresholds determined by different methods in repeated exercise tests were correlated with cardiorespiratory variables and variables of muscle metabolic profile in 33 men aged 20-50 years. Aerobic threshold was determined from blood lactate, ventilation, and respiratory gas exchange by two methods (AerT1 and AerT2) and anaerobic threshold from venous lactate (AnTLa), from ventilation and gas exchange (AnTr) and by using the criterion of 4 mmol.1(-1) of venous lactate (AnT4mmol). In addition to ordinary correlative analyses, applications of LISREL models were used. The 8 explanatory variables chosen for the regression analyses were height, relative heart volume, relative diffusing capacity of the lung, muscle fiber composition, citrate synthase (CS) and succinate dehydrogenase activities, the lactate dehydrogenase--CS ratio, and age. They explained 58% of the variation in AerT1, 73.5% that of AerT2, 71% that of AnTr, 74.5% that of AnTLa, and 67.5% that of AnT4mmol.AerT and AnT alone explained 77% of the variation in each other. Both AerT and AnT were determined mainly by a muscle metabolic profile, with the CS activity of vastus lateralis as the strongest determinant. The factor 'submaximal endurance' which was measured with AerT and AnT seemed to be slightly more closely connected to 'muscle metabolic profile' than was 'maximal aerobic power' (= VO2max), but both also correlated strongly with each other (r = 0.92).     

Cardiovascular and respiratory physiology of tuna: adaptations for support of exceptionally high metabolic rates

Synopsis Both physical and physiological modifications to the oxygen transport system promote high metabolic performance of tuna. The large surface area of the gills and thin blood-water barrier means that O₂ utilization is high (30–50%) even when ram ventilation approaches 101 min^–1kg^–1. The heart is extremely large and generates peak blood pressures in the range of 70–100 mmHg at frequencies of 1–5 Hz. The blood O₂ capacity approaches 16 ml dl^–1 and a large Bohr coefficient (–0.83 to –1.17) ensures adequate loading and unloading of O₂ from the well buffered blood (20.9 slykes). Tuna muscles have aerobic oxidation rates that are 3–5 times higher than in other teleosts and extremely high glycolytic capacity (150 mol g^–1 lactate generated) due to enhanced concentration of glycolytic enzymes. Gill resistance in tuna is high and may be more than 50% of total peripheral resistance so that dorsal aortic pressure is similar to that in other active fishes such as salmon or trout. An O₂ delivery/demand model predicts the maximum sustained swimming speed of small yellowfin and skipjack tuna is 5.6 BL s^–1 and 3.5 BL sec^–1, respectively. The surplus O₂ delivery capacity at lower swimming speeds allows tuna to repay large oxygen debts while swimming at 2–2.5 BL s^–1. Maximum oxygen consumption (7–9 × above the standard metabolic rate) at maximum exercise is provided by approximately 2 × increases in each of heart rate, stroke volume, and arterial-venous O₂ content difference.Paper from International Union of Biological Societies symposium The biology of tunas and billfishes: an examination of life on the knife edge, organized by Richard W. Brill and Kim N. Holland.     

Myosin isoforms and fibre types in limb muscles of Australian marsupials: adaptations to hopping and non-hopping locomotion

Using immunohistochemistry and SDS-PAGE, we studied the myosin heavy chain (MyHC) composition and fibre type distribution of hindlimb muscles of hopping and non-hopping Australian marsupials. We showed that hindlimb muscles of a bandicoot (Isoodon obesulus, order Peramelomorphia) and a small macropodoid, the brushtail bettong (Bettongia penicillata) expressed four MyHCs, slow, 2a, 2x and 2b, and had the corresponding fibre types as other macropods reported earlier. The fastest and most powerful 2b fibres predominated in most bettong hindlimb muscles, but were absent in the gastrocnemius and the flexor digitorum profundus, which are involved in elastic strain energy saving during hopping. The gastrocnemius of four large macropodids also showed little or no 2b MyHC, whereas this isoform was abundant in their tibialis anterior, which is not involved in elastic energy saving. In contrast, 2b MyHC predominated in the gastrocnemius of four non-hopping marsupials. These results suggest that absence of 2b fibres may be a general feature of macropodoid muscles involved in elastic energy saving. Large eutherians except llamas and pigs also have no 2b fibres. We hypothesize that 2x and 2a fibres perform better than 2b fibres in the storage and recovery of kinetic energy during locomotion in both marsupials and eutherians.     

Benefits of caffeine ingestion on sprint performance in trained and untrained swimmers

The influence of specific training on benefits from caffeine (Caf) ingestion was examined during a sprint test in a group of highly trained swimmers (T) and compared with the response of a group of untrained occasional swimmers (UT). Seven T and seven UT subjects swam freestyle two randomly assigned 2 x 100 m distances, at maximal speed and separated by 20 min of passive recovery, once after Caf (250 mg) and once after placebo (Pla) ingestion. Anaerobic capacity was assessed by the mean velocity (meters per second) during each 100 m and blood was sampled from the fingertip just before and 1, 3, 5, 7, and 9 min after each 100 m for resting and maximal blood lactate concentration ([la-]b,max) determination. The [la-]bmax was significantly enhanced by Caf in both T and UT subjects (P less than 0.01). However, only T subjects exhibited significant improvement in their swimming velocity (P less than 0.01) after Caf or any significant impairment during the second 100 m. In light of these results, it appears that specific training is necessary to benefit from the metabolic adaptations induced by Caf during supramaximal exercise requiring a high anaerobic capacity.     

Capillary distribution and metabolic histochemistry of the lateral propulsive musculature of pelagic teleost fish

Metabolic and vascular adaptation of teleost lateral propulsive musculature to an active mode of life was investigated in four pelagic teleosts (mackerel, yellowtail scad, pilchard and Australian salmon). Histochemical profiles and capillarisation data of the red and white muscle were compared to those of less active demersal species. Pelagic white muscle stained positively for the aerobic enzymes succinate dehydrogenase and NADH diaphorase, and had both subsarcolemmal and intermyofibrillar mitochondria which corresponded to the loci of the histochemical stain. Subsarcolemmal mitochondria tended to be localised close to capillaries. In contrast, white muscle from demersal species was unstained for the same enzymes and was devoid of mitochondria. Red muscle of all species had abundant mitochondria and stained intensely for aerobic enzymes. Capillarisation was quantified by determining the percentage of fibres surrounded by a given number of peripheral capillaries, mean fibre diameter, mean number of peripheral capillaries, capillary: fibre ratio and sharing factor where appropriate. Red muscle of mackerel, Australian salmon, pilchard and scad are better vascularised than red muscle of the flathead having 153, 200, 242, 291 and 309 microns 2 of cross-sectional fibre area per peripheral capillary, respectively. White muscle of mackerel, pilchard and scad are better vascularised than white muscle of the Australian salmon and flathead having 2040, 3367, 4992, 9893 and 10,469 microns 2 of cross-sectional fibre area per peripheral capillary, respectively. Red muscle of Australian salmon had distinct regional variation. Deep red muscle was found to be more highly vascularised (4.2 peripheral capillaries per muscle fibre) than lateral red muscle (1.9 peripheral capillaries per muscle fibre). Red muscle of the other species was less heterogeneous. White muscle capillarisation was slightly variable in all species. It is concluded that the white muscle of the pelagic species studied is functionally and structurally adapted for sustained aerobic activity with relatively abundant mitochondria being preferentially situated close to the source of gas and metabolite exchange.     

Computational methods for the analysis of swimming biomechanics

A series of computer programs is presented which enables the analysis of fish body shape and mass distributions, spine positions, spine curvatures and coordinates for the centre of mass. Data are derived from silhouette outlines of swimming fish, white muscle strains during swimming, white muscle force-time development functions for body bending cycles, muscle force and power production along the whole fish body and hydrodynamic efficiencies for fast-start swimming behaviours.     

Morphology and locomotor adaptations of the foot in early Oligocene anthropoids

Newly discovered foot bones of Aegyptopithecus are described and compared to those of Apidium and Dolichocebus. Locomotor adaptations are inferred for African early Oligocene propliopithecids, parapithecids, and for Argentine early Oligocene Dolichocebus. All show an anthropoid grade of development in their foot anatomy. Tarsals of Aegyptopithecus compare best with those of Miocene hominoids. Apidium shares derived calcaneal features that link it with Old World monkeys. Dolichocebus exhibits a very generalized platyrrhine talar morphology akin to that seen in Saimiri, Callicebus, Cebus, and Aotus. The morphology of early Oligocene primate foot bones suggests that at least three quite distinct groups, corresponding to three recognized superfamilies, were present in the early Oligocene of South America and Africa.     

Anguilliform body dynamics: a continuum model for the interaction between muscle activation and body curvature

A two dimensional continuum model for the body mechanics of the lamprey is derived from a simple discrete rod and pivot structure. Each element in the discrete structure consists of two smoothly jointed light rods with perpendicular extensions at each of the midpoints between which is fixed a quasi muscle segment. The muscle segment is attributed with the viscous and elastic properties of all the animal tissue plus the ability to produce force. The travelling wave of muscle activation in the real animal is modelled by a corresponding time dependent forcing term at each segment. A linearisation of the ensuing continuum model, corresponding to low curvature dynamics, is investigated. The profiles obtained compare favourably with those of a lamprey moving out of water on a smooth surface. In addition the phase difference at each point on the body between the wave of muscle activation and the mechanical wave observed on the body indicates that the mechanical wave progresses slower than, but at the same frequency as, the wave of activation; this is a property that is also observed in the freely swimming lamprey.     

Muscle architecture of the upper limb in the orangutan

We dissected the left upper limb of a female orangutan and systematically recorded muscle mass, fascicle length, and physiological cross-sectional area (PCSA), in order to quantitatively clarify the unique muscle architecture of the upper limb of the orangutan. Comparisons of the musculature of the dissected orangutan with corresponding published chimpanzee data demonstrated that in the orangutan, the elbow flexors, notably M. brachioradialis, tend to exhibit greater PCSAs. Moreover, the digital II-V flexors in the forearm, such as M. flexor digitorum superficialis and M. flexor digitorum profundus, tend to have smaller PCSA as a result of their relatively longer fascicles. Thus, in the orangutan, the elbow flexors demonstrate a higher potential for force production, whereas the forearm muscles allow a greater range of wrist joint mobility. The differences in the force-generating capacity in the upper limb muscles of the two species might reflect functional specialization of muscle architecture in the upper limb of the orangutan for living in arboreal environments.     

Red and white muscle activity and kinematics of the escape response of the bluegill sunfish during swimming

Summary We quantified midline kinematics with synchronized electromyograms (emgs) from the red and white muscles on both sides of bluegill sunfish (Lepomis macrochirus) during escape behaviors which were elicited from fish both at a standstill and during steady speed swimming. Analyses of variance determined whether or not kinematic and emg variables differed significantly between muscle fiber types, among longitudinal positions, and between swimming versus standstill trials.At a given longitudinal location, both the red and white muscle were usually activated synchronously during both stages of the escape behavior. Stage 1 emg onsets were synchronous; however, the mean durations of stage 1 emgs showed a significant increase posteriorly from about 11 to 15 ms. Stage 2 emgs had significant posterior propagation, but the duration of the stage 2 emgs was constant (17 ms). Posterior emgs from both stages occurred during lengthening of the contractile tissue (as indicated by lateral bending). Steady swimming activity was confined to red muscle bursts which were propagated posteriorly and had significant posterior decrease in duration from about 50% to 37% of a cycle. Fish performed escape responses during all phases of the steady swimming motor pattern. All kinematic events were propagated posteriorly. Furthermore, no distinct kinematic event corresponded to the time intervals of the stage 1 and 2 emgs. The rate of propagation of kinematic events was always slower than that of the muscle activity. The phase relationship between lateral displacement and lateral bending also changed along the length of the fish. Escape responses performed during swimming averaged smaller amplitudes of stage 2 posterior lateral displacement; however, most other kinematic and emg variables did not vary significantly between these two treatments.Abbreviations A angle of lateral flexion (bending) of midline at a single point in time - A1, A2 change in A from T₀ to T₁ and from T₁ to T₂ - AMX maximal lateral flexion concave towards the side of the stage 1 emg - AMXR equals AMX minus A at T₀ - AT1, AT2 lateral flexion at T₁ and T₂ - DUR1, DUR2 durations of stage 1 and stage 2 emgs - emg electromyogram - ON2 onset time of stage 2 emg - RELDUR relative duration of steady swimming emg - T₀, T₁, T₂ times of stage 1 emg onset, latest stage 1 emg offset and latest stage 2 emg offset standardized such that T₀ = 0 - TAMX, TAMN, TYMX times of maximal lateral flexion, no lateral flexion and maximum lateral displacement - Y1, Y2 amounts of lateral displacement from T₀ to T₁ and from T₁ to T₂ - YMXR relative amount of lateral displacement from T₀ to TYMX     

Activation of two forms of locomotion by a previously identified trigger interneuron for swimming in the medicinal leech

Higher-order projection interneurons that function in more than one behavior have been identified in a number of preparations. In this study, we document that stimulation of cell Tr1, a previously identified trigger interneuron for swimming in the medicinal leech, can also elicit the motor program for crawling in isolated nerve cords. We also show that motor choice is independent of the firing frequency of Tr1 and amount of spiking activity recorded extracellularly at three locations along the ventral nerve cord prior to Tr1 stimulation. On the other hand, during Tr1 stimulation there is a significant difference in the amount of activity elicited in the ventral nerve cord that correlates with the motor program activated. On average, Tr1 stimulation trials that lead to crawling elicit greater amounts of activity than in trials that lead to swimming.     

Review of the life history,fisheries, and stock assessment for small tunas in the Atlantic Ocean

Reviews in Fish Biology and Fisheries - Despite being an important source of wealth and food security for many countries, most of the small tuna stocks in the Atlantic Ocean and Mediterranean Sea...     

反相高效液相色谱法测定厌氧菌有机酸代谢产物

建立反相高效液相色谱测定厌氧菌代谢发酵有机酸产物(乙酸、乳酸)的方法并用于测定乳酸菌代谢发酵产物中的含量。反相高效液相方法是一种简单、准确、灵敏的方法,可用于同时定量测定厌氧菌的有机酸代谢产物。     

Current methodological refinements for the acquisition of life history information in fishes: paradigms from pan-oceanic billfishes.

1. Many factors contribute to hinder progress in estimating and verifying age, growth, and life history strategies of billfishes. It is necessary to discern growth of an individual fish to circumvent problems in substantiating age, growth, longevity and age at maturity. These biological characteristics allow us to discover what life history periods are critical to survival and reproduction. 2. Two theoretical approaches may be considered for studying the age of billfish: Age may be delineated in terms of the passage of time (chronological age), or may be examined as the progression of physiological development (physiological age). 3. Hard tissues such as otoliths, spines, vertebrae and post-mitotic tissues contain a plethora of biological and ecological information documenting a fish's chronological and physiological age and individual life history. In calcified tissues, this information can be obtained when the proper techniques are used to investigate the structural and chemical components of billfish hard parts. Chemical analyses of stable isotopes and elemental concentrations in calcified tissues suggest that calcified tissues contain hydrographic, nutritional and migrational information--life history information. 4. Utilization of structural and chemical analyses of billfish otoliths, vertebrae, and other hard parts, enables specific phases of growth to be linked to environmental occurrences. Measurement of the metabolically accumulated cellular pigment, lipofuscin, in post-mitotic tissue may make it possible to define physiological age or readiness. Internal and external structural and chemical analyses of otoliths, vertebrae, and other hard parts, combined with biochemical assays of post-mitotic tissue will greatly enhance studies of life history. The methods presented provide insights into means by which life history knowledge can be obtained.     

Energetically costly behaviour and the evolution of resting metabolic rate in insects

1. A general hypothesis is presented to explain interspecific differences in size-independent resting metabolic rate. This hypothesis is based on a presumed trade-off between a low resting metabolism and adaptations of metabolism during activity.
2. With such a trade-off, selection to reduce resting metabolism is less intense in active species than in species where resting metabolism constitutes a large proportion of the daily metabolic costs. Those animals that spend more energy on activity should therefore have a higher resting metabolic rate than animals that spend less energy on activity.
3. A literature review reveals that flying insects have higher resting metabolic rates than species that use energetically less demanding types of locomotion.
4. Insects producing acoustic advertisement signals can be shown to have higher mass-independent resting metabolic rates than closely related species without this energetically demanding behaviour.
5. Literature data on vertebrate resting metabolic rates are also consistent with the presented hypothesis: the more energy animals spend on activity, the higher the mass-independent resting metabolic rate.     

The metabolic cost of walking in humans, chimpanzees, and early hominins

Bipedalism is a defining feature of the hominin lineage, but the nature and efficiency of early hominin walking remains the focus of much debate. Here, we investigate walking cost in early hominins using experimental data from humans and chimpanzees. We use gait and energetics data from humans, and from chimpanzees walking bipedally and quadrupedally, to test a new model linking locomotor anatomy and posture to walking cost. We then use this model to reconstruct locomotor cost for early, ape-like hominins and for the A.L. 288 Australopithecus afarensis specimen. Results of the model indicate that hind limb length, posture (effective mechanical advantage), and muscle fascicle length contribute nearly equally to differences in walking cost between humans and chimpanzees. Further, relatively small changes in these variables would decrease the cost of bipedalism in an early chimpanzee-like biped below that of quadrupedal apes. Estimates of walking cost in A.L. 288, over a range of hypothetical postures from crouched to fully extended, are below those of quadrupedal apes, but above those of modern humans. These results indicate that walking cost in early hominins was likely similar to or below that of their quadrupedal ape-like forebears, and that by the mid-Pliocene, hominin walking was less costly than that of other apes. This supports the hypothesis that locomotor energy economy was an important evolutionary pressure on hominin bipedalism.     

The effects of temperature on metabolic interaction between digestion and locomotion in juveniles of three cyprinid fish (Carassius auratus, Cyprinus carpio and Spinibarbus sinensis)

To test whether the effects of temperature on the metabolic mode changed among different fish species, we investigated the specific dynamic action (SDA) and swimming performance of fasting and fed fish at 15 and 25°C in three juvenile Cyprinidae fish species: goldfish (Carassius auratus), common carp (Cyprinus carpio) and qingbo (Spinibarbus sinensis). Both taxon and temperature had significant effects on the resting oxygen consumption rate (M˙O(rest)), SDA and swimming performance (p<0.05). In addition, the effect of temperature differed significantly among the different species (interaction effect, p<0.05). Under the low temperature condition, digestion had no effect on either critical swimming speed (U(crit)) or the active MO(2) (MO(active)) for all fish species (additive metabolic mode). When the temperature was increased from 15 to 25°C, the metabolic scope (MS) for digestion increased approximately 182, 49 and 17%, and the MS for locomotion increased approximately 129, 58 and 138% in goldfish, common carp and qingbo, respectively. The total metabolic demands for both digestion and locomotion (i.e., the sum of digestive MS and locomotive MS) increased approximately 143, 56 and 112% in goldfish, common carp and qingbo, respectively. The total MS for both digestion and locomotion (the difference between MO(active) in fed fish and MO(rest) in fasting fish) increased approximately 106, 58 and 78% in goldfish, common carp and qingbo, respectively. Thus, the MS for locomotion in fed goldfish decreased due to the large increase in digestive function at the high temperature, and the U(crit) of fed goldfish decreased by 11% compared to that of fasting fish (p<0.05) (digestion-priory metabolic mode). The metabolic mode of qingbo changed to locomotion-priority mode, as illustrated by the large increase in locomotive MS in response to the increase in temperature. In the common carp, temperature had no effect on metabolic mode as illustrated by the parallel increases in cardio-respiratory capacity and metabolic capacity of digestive and locomotive organs. A discussion on the changes in metabolic mode in response to temperature and its possible relationship with the metabolic characteristics of a given fish species was also documented in this paper.     

Implication of light sources and microbial activities on degradation of sulfonamides in water and sediment from a marine shrimp pond

In this study, the effects of natural, visible and ultraviolet lights, microbial activities and aerobic and anaerobic conditions on degradation of four different sulfonamide antibiotics (SAs) were studied. Water and sediment collected from a marine shrimp pond were examined and a factorial design was employed to evaluate the effects of selected parameters. The results showed that all the SAs in water and sediment had significant declines attributed to natural light and microbial activities. The half-lives (t_1/2s) of SAs in non-sterile water and sediment samples under natural light were 2.0-15.0 and 0.7-7.3 days, respectively, and slowed to 2.9-62.9 and 6.9-85.6 days after sterilized. Moreover, the declines of SAs were significantly faster under ultraviolet than visible light with 36.5-70.9% shorter t_1/2s. Anaerobic condition was also effective on declines of SAs in sediment. Both sulfate-reducing and methanogenic microbes were directly involved in the decline of SDM, and indirectly contributed to SMX declines.     

Assessment of the biodegradability of a monosulfonated azo dye and aromatic amines

Biodecolourisation of an azo dye by anaerobic cultures using a liposomal textile levelling agent as primary substrate was assessed. Liposomes seem to facilitate the uptake of the dye (Acid Orange 7) by anaerobic biomass, leading to a fast decolourisation (colour removal of 96% was achieved in the first sample port of the reactor profiles). On the other hand, the presence of dye (60–300 mg l⁻¹) caused a decrease in the chemical oxygen demand (COD) degradation rate (4.1–2.5 g COD removed l⁻¹ d⁻¹ for 60 and 300 mg l⁻¹ of dye, respectively), suggesting inhibitory effects.Aerobic degradation of aromatic amines was investigated in aerobic respirometric assays with different types of inocula. Sulfanilic acid and aniline were mineralised by inocula with a significant microbiological diversity, even with domestic effluent. These results were confirmed by a significant reduction of COD, total organic carbon (TOC) and a high oxygen consumption (biochemical oxygen demand/theoretical oxygen demand), 92±4%. Kinetic analysis showed that a sigmoid function describes quite well the experimental data, even better than the exponential model. Orthanilic and metanilic acids and 1-amino-2-naphtol were persistent under the tested conditions.