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.     

Fever and sickness behavior during an opportunistic infection in a free-living antelope, the greater kudu (Tragelaphus strepsiceros)

To study their thermal responses to climatic stress, we implanted seven greater kudu (Tragelaphus strepsiceros) with intra-abdominal, brain, carotid, and subcutaneous temperature data loggers, as well as an activity logger. Each animal was also equipped with a collar holding a miniature black globe thermometer, which we used to assess thermoregulatory behavior. The kudu ranged freely within succulent thicket vegetation of the Eastern Cape Province, South Africa. The kudu spontaneously developed a bacterial pneumonia and consequent fever that lasted between 6 and 10 days. The fever was characterized by a significant increase in mean 24-h abdominal temperature from 38.9 +/- 0.2 degrees C to 40.2 +/- 0.4 degrees C (means +/- SD, t(6) = 11.01, P < 0.0001), although the amplitude of body temperature rhythm remained unchanged (t(6) = 1.18, P = 0.28). Six of the kudu chose warmer microclimates during the fever than when afebrile (P < 0.0001). Despite the selection of a warmer environment, on the first day of fever, the abdominal-subcutaneous temperature difference was significantly higher than on afebrile days (t(5) = 3.06, P = 0.028), indicating vasoconstriction. Some kudu displayed increased frequency of selective brain cooling during the fever, which would have inhibited evaporative heat loss and increased febrile body temperatures, without increasing the metabolic maintenance costs of high body temperatures. Average daily activity during the fever decreased to 60% of afebrile activity (t(6) = 3.46, P = 0.014). We therefore have recorded quantitative evidence for autonomic and behavioral fever, as well as sickness behavior, in the form of decreased activity, in a free-living ungulate species.     

Effect of thyroxine and noradrenaline on thermoregulation, cardiac rate and oxygen consumption in the monitor lizard Varanus albigularis albigularis

1. 1. At the preferred body temperature (35°C) resting metabolic rate was 0.155 ± 0.015 ml O₂/g·h and heart rate was 54 ± 11 beats/min. Spontaneous activity at this body temperature caused a two-fold increase in heart rate and a six-fold increase in O₂ consumption. Maximum values being 0.86 ml/g·h with an O₂ pulse of 13.6 × 10⁻⁵ ml/g·beat.

2. 2. Pre-treatment for seven days with thyroxine caused a 27% increase in resting metabolic rate and a 63% increase in the thermal gradient between core and ambient temperature at the preferred body temperature.

3. 3. Noradrenaline reduced heart rate but had no effect at the dosage recommended on metabolic rate at body temperatures of either 35 or 15°C, suggesting that non-shivering thermogenesis is absent in lizards. The evolutionary implications of these results have been briefly discussed.

冷驯化对中缅树鼩产热能力的影响

在 ( 5± 1)℃条件下对中缅树 (Tupaiabelangeri)进行低温胁迫处理 ( 0～ 2 8d) ,测定其冷驯化过程中的静止代谢率 (RMR)、非颤抖性产热 (NSTmax)、冷诱导最大产热 (CIRMR)、体重、体温等生理指标 ,探讨低温对中缅树产热能力的影响。结果表明 :①冷驯化期间中缅树体重增加 ,体温降低 ,产热能力显著增强 ;②在冷驯化过程中 ,增加RMR和CIRMR是中缅树抵抗低温胁迫的主要产热模式。     

The metabolic cost of fever in Pekin ducks

Fever is an energetically expensive component of the mammalian immune system’s acute phase response. Like mammals, birds also develop fever when exposed to pathogens, but, as yet, the energy requirements of febrile mediation in birds are not known. We injected ducks (Anas platyrhynchos; n=8) with 100 μ kg⁻¹ LPS or sterile isotonic saline and recorded their core body temperatures while measuring their O₂ consumption and CO₂ production in an open-flow respirometric circuit. Lipopolysaccharide elicited robust increases in the core body temperatures of our birds. The metabolic rate of the ducks increased about 80 min after treatment with LPS, relative to the metabolic rate of saline injected birds, and peaked 100 min later when the highest body temperatures were recorded. Our ducks increased their energy expenditure by 33.1% for about 3 h to mount a febrile response that, on average, increased their body temperature 1.4 °C. Studies with humans and rats, kept at thermoneutral temperatures, found a 10-15% increase in metabolic rate for every 1 °C increase in body temperature. The increase in metabolic rate, reported here (23%/°C), is noticeably higher and we conclude that febrile mediation is metabolically more expensive in Pekin ducks than in mammals.     

Increased Prevalence of Anellovirus in Pediatric Patients with Fever

The Anelloviridae family consists of non-enveloped, circular, single-stranded DNA viruses. Three genera of anellovirus are known to infect humans, named TTV, TTMDV, and TTMV. Although anelloviruses were initially thought to cause non-A-G viral hepatitis, continued research has shown no definitive associations between anellovirus and human disease to date. Using high-throughput sequencing, we investigated the association between anelloviruses and fever in pediatric patients 2–36 months of age. We determined that although anelloviruses were present in a large number of specimens from both febrile and afebrile patients, they were more prevalent in the plasma and nasopharyngeal (NP) specimens of febrile patients compared to afebrile controls. Using PCR to detect each of the three species of anellovirus that infect humans, we found that anellovirus species TTV and TTMDV were more prevalent in the plasma and NP specimens of febrile patients compared to afebrile controls. This was not the case for species TTMV which was found in similar percentages of febrile and afebrile patient specimens. Analysis of patient age showed that the percentage of plasma and NP specimens containing anellovirus increased with age until patients were 19–24 months of age, after which the percentage of anellovirus positive patient specimens dropped. This trend was striking for TTV and TTMDV and very modest for TTMV in both plasma and NP specimens. Finally, as the temperature of febrile patients increased, so too did the frequency of TTV and TTMDV detection. Again, TTMV was equally present in both febrile and afebrile patient specimens. Taken together these data indicate that the human anellovirus species TTV and TTMDV are associated with fever in children, while the highly related human anellovirus TTMV has no association with fever.     

Energy metabolism and evaporative water loss in the European free-tailed bat and Hemprich's long-eared bat (Microchiroptera): species sympatric in the Negev Desert

We compared the thermoregulatory abilities of two insectivorous bat species, Tadarida teniotis (mean body mass 32 g) and Otonycteris hemprichii (mean body mass 25 g), that are of different phylogenetic origins and zoogeographic distributions but are sympatric in the Negev Desert. At night, both were normothermic. By day, both were torpid when exposed to ambient temperatures (T(a)) below 25 degrees Celsius, with concomitant adjustments in metabolic rate (MR). Otonycteris hemprichii entered torpor at higher T(a) than T. teniotis, and, when torpid, their body temperatures (T(b)) were 1 degrees -2 degrees Celsius and 5 degrees -8 degrees Celsius above T(a), respectively; MR was correspondingly reduced. At night, the lower critical temperature of T. teniotis was 31.5 degrees Celsius, and that of O. hemprichii was 33 degrees Celsius. Mean nocturnal thermoneutral MR of T. teniotis was 37% greater than that of O. hemprichii. At high T(a), evaporative water loss (EWL) increased markedly in both species, but it was significantly higher in T. teniotis above 38 degrees Celsius. In both species, the dry heat transfer coefficient (thermal conductance) followed the expected pattern for small mammals, by day and by night. Total EWL was notably low in normothermic and torpid animals of both species, much lower than values reported for other bats, indicating efficient water conservation mechanisms in the study species. Comparing thermoregulatory abilities suggests that O. hemprichii is better adapted to hot, arid environments than T. teniotis, which may explain its wider desert distribution. By both standard and phylogenetically informed ANCOVA, we found no differences in basal metabolic rate (BMR) between desert and nondesert species of insectivorous bats, substantiating previous studies suggesting that low BMR is a characteristic common to insectivorous bats in general.     

Significance of anomalous thermoregulation in the pre-diabetic spiny mouse (Acomys cahirinus): oxygen consumption and temperature regulation

In keeping with studies of other desert rodents, the potentially diabetic spiny mouse has been demonstrated to have a very low basal metabolic rate, disproportionate to its body weight. The maintenance of a lower body temperature in response to high environmental temperatures and a lack of increase in metabolic rate in response to cooling have also been demonstrated. Assessments of "mechanical efficiency" have shown that spiny mice carry a potential selective advantage under fasting conditions. The findings, some of which are similar to those noted in other desert rodents, and in other species showing either spontaneous or induced hyperglycaemia, suggest that the low metabolic rate is at least partly based on ineffective glucose utilization. This phenomenon may be the common denominator of the survival advantage which has allowed both the successful evolution of species inhabiting warm, arid climes, and the persistence of the diabetic genotype in animal and human populations.     

Central and peripheral injections of ACTH (1–24) reduce fever in adrenalectomized rabbits

Central administration of ACTH (1-24) reduces fever in normal rabbits in doses that have no effect on afebrile body temperature. Previous experimental and clinical reports indicate that peripheral administration of both ACTH and corticosteroids reduces fever, and since central injection of corticosteroids can also lower fever it might be that the antipyretic effect of intracerebroventricular (ICV) ACTH (1-24) is due to adrenal stimulation. To learn whether this endogenous central peptide can produce antipyresis independently, ACTH (1-24) was injected ICV in bilaterally adrenalectomized (ADX) rabbits made febrile by IV injections of leukocytic pyrogen (LP). ACTH (250 ng) given ICV reduced fever in these animals and had a slight hypothermic effect when given to the same rabbits when they were afebrile. Doses of 25-75 ng reduced fever without influencing normal body temperature. Intravenous injections of ACTH (2.5 micrograms) also lowered fever caused by IV LP in ADX rabbits. The present findings raise the possibility that release of endogenous central ACTH, and perhaps entry into the brain of circulating ACTH, the release of which is known to increase in fever, limits the magnitude of the febrile response by influencing central temperature controls.     

内蒙古草原小毛足鼠的活动性、代谢特征和体温的似昼夜节律

小毛足鼠(Phodopus roborovskii)是分布在内蒙古草原沙地的一种小型哺乳动物,关于其生物学和生态学特征,尤其是生理学特征还知之甚少。似昼夜节律是动物行为学和生理生态学中备受关注的一个领域。在室内条件下通过体内埋置无线电传感器连续监测小毛足鼠的体温、用自动监测系统连续监测活动性和TSE LabMaster呼吸代谢测定系统连续测定了其代谢率的昼夜节律性。结果发现:小毛足鼠在夜间的平均体温是(37.27±0.39)℃,昼间的平均体温是(36.11±0.18)℃;在夜间的平均代谢率是(4.65±1.10)mLO2·g-1·h-1,昼间的平均代谢率是(3.09±0.42)mLO2·g-1·h-1;在夜间的平均活动率为(237±145)次/0.1h,昼间的平均活动率为(38±5)次/0.1h。小毛足鼠的代谢率、活动性和体温的峰值相位主要集中在夜间,属典型的夜行性动物。实验结果从行为学特性和生理学特征等新的角度支持了野外观察小毛足鼠是夜行性动物的推断。综合活动性、代谢率和体温三方面同步变化的特征,为小毛足鼠的似昼夜节律变化提供了新的机理性解释。研究也表明小毛足鼠是研究野生动物似昼夜节律变化机理的好模型。     

Thermoregulatory patterns of two sympatric rodents: Otomys unisulcatus and Parotomys brantsii

1. The adaptations to an arid environment in two closely related rodent species were investigated. 2. The rate of oxygen consumption (VO2), body temperature (Tb), evaporative water loss and minimal conductance in Otomys unisulcatus and Parotomys brantsii were determined under controlled conditions at ambient temperatures (Ta), ranging from 11-31 C. 3. Physiological features atypical of desert-adapted rodents include a basal metabolic rate higher than predicted by body mass, the low "lower critical temperature" and symptoms of heat stress at 31 degrees C. 4. The low Tb and wide thermoneutral zone recorded for both species are characteristic of desert rodent species. 5. These species' physiological abilities reflect their mesic phylogeny and we suggest that behaviour must play an important role in their survival in semi-arid areas.     

Analysis of T-cell subset proliferation at afebrile and febrile temperatures: differential response of Lyt-1+23- lymphocytes to hyperthermia following mitogen and antigen stimulation and its functional consequence on development of cytotoxic lymphocytes

Poikilotherms are now known to increase their survival by behaviorally induced fevers in response to pathogenic infection. Increased host resistance to viral and bacterial infections has also been noted in homeotherms whose body temperature has been elevated by manipulation of ambient temperature. These observations suggest that fever may increase host resistance by augmenting acquired immunity; thus, this highly conserved response during evolution may provide a survival advantage against environmental pathogens. This possibility has prompted us to investigate the influence of a temperature characteristic of a modest fever in humans (39 degrees C) on T-cell proliferation and function. Our studies revealed that T-cell mitogenesis was enhanced when cultures were incubated at the febrile temperature (39 degrees C). Analysis of T-cell subsets demonstrated that temperature enhanced the mitogenic (Concanavalin A) response of Lyt-1+23- splenocytes; in contrast, hyperthermia was deleterious to lectin-driven proliferation of the Lyt-1-23+ population even in the presence of large quantities of recombinant interleukin-2 (rIL-2). B-cell mitogenesis was invariably inhibited by hyperthermia over a broad range of concentrations of lipopolysaccharide (LPS). Although T-cell mitogenesis was enhanced at the febrile temperature, T-cell proliferation induced by alloantigens or by a murine pathogen, Sendai virus (SV), was diminished at the febrile temperature. Hyperthermia inhibited SV-induced proliferation of Lyt-1+23- lymphocytes, indicating that a febrile temperature can either augment or inhibit T-cell proliferation of the same T-cell subset depending upon the activation signal (i.e., lectin or antigen). Because effector cell development depends upon antigen-induced clonal expansion (proliferation), we evaluated the influence of temperature on primary cytotoxic thymus (T)-derived lymphocyte (CTL) responses against alloantigens and secondary CTL responses against SV under afebrile and febrile conditions. We consistently observed that the induction of alloreactive and virus-specific CTL was diminished in cultures incubated at the elevated temperature, suggesting that a thermosensitive event(s) exists in the progression of CTL derived from either CTL precursors (CTLp) or memory CTL. Furthermore, hyperthermia reduced the number of SV-specific CTL detectable by limiting dilution analysis, suggesting that another event independent of clonal expansion was thermolabile during effector cell development. In view of these results, we suggest that it may be premature to conclude that the observed increase in host resistance induced by a febrile state is mediated by enhanced cell-me     

Fever in young lambs: hypoxemia alters the febrile response to a small dose of bacterial pyrogen.

Experiments were done on eight young lambs to investigate the effects of hypoxemia on the body temperature, metabolic and cardiovascular responses to intravenous administration of a small dose of bacterial pyrogen (0.3 micrograms lipopolysaccharide extracted from Salmonella Abortus Equi; SAE). Each lamb was anaesthetized with halothane and prepared for sleep staging and measurements of cardiac output, arterial and mixed-venous haemoglobin oxygen saturations, body-core and ear-skin temperatures. Three experiments were done on each lamb, the first being done no sooner than three days after surgery. The first experiment consisted of establishing the thermal neutral environment during normoxemia (ie, environmental temperature at which total body oxygen consumption was minimal while body temperature was maintained) for each lamb. The second and third experiments were done at the lamb's thermoneutral environment as determined on day 1. One experiment was done during normoxemia (ie, control condition, SaO2 approximately 90%) and one experiment was done during hypoxemia (ie, experimental condition, SaO2 approximately 50%). Measurements were made during a control period and during one-minute experimental periods at 10 minute intervals for 120 minutes following administration of 0.3 micrograms of bacterial pyrogen in sterile saline. Administration of SAE produced a short-lived fever of about 0.8 degrees C in the normoxemic lambs, whereas no change in body-core temperature was observed in the hypoxemic lambs. During normoxemia, the increase in body-core temperature was preceded by peripheral vasoconstriction, the onset of shivering, and a surge in total body oxygen consumption. The increase in total body oxygen consumption was met primarily by an increase in total body oxygen extraction during the development of fever. Cardiac index, heart rate, and systemic oxygen transport increased during the peak body-core temperature response. Systemic arterial blood pressure did not change significantly during the febrile response; however, pulmonic arterial blood pressure increased. During hypoxemia, peripheral vasoconstriction and shivering occurred following administration of SAE, but there was no change in total body oxygen consumption or body-core temperature. Thus, our data provide evidence that hypoxemia alters the febrile response of young lambs to bacterial pyrogen. The precise mechanism remains to be determined.     

Basal rate of metabolism and temperature regulation of two desert herbivorous octodontid rodents: Octomys mimax and Tympanoctomys barrerae

Summary We studied the energetics of two herbivorous desert rodents from South America. The two species had slightly lower basal metabolic rates, lower thermal conductances, and higher temperature differentials than those expected from their body mass. Mass-independent basal rates of metabolism were higher than those reported for seed-eating desert rodents from North America. Our observations support the hypothesis that desert rodents that eat foods with high water content have higher mass-independent metabolic rates than seed-eating desert rodents.     

龙种金鱼和蛋种金鱼线粒体DNA控制区的序列分析

利用PCR技术扩增了红龙睛、墨龙睛、虎头和水泡眼4种金鱼线粒体DNA控制区部分核苷酸序列,长度分别为724、724、720、722bp.测序结果显示,龙种金鱼红龙睛、墨龙睛的线粒体DNA控制区的序列完全相同,同源性为100%;蛋种金鱼虎头、水泡眼的序列相差4个碱基,同源性为99.4%.研究表明,这4个金鱼品种之间的同源性都很高,而同品系金鱼的亲缘关系相对较近.引用Genbank中鲫鱼的序列,构建了金鱼和鲫鱼的NJ分子系统树,从分子水平证实了金鱼起源于鲫鱼.     

Adaptation of biological membranes to temperature. The lack of homeoviscous adaptation in the sarcoplasmic reticulum

Temperature adaptation of biological membranes was examined by comparing the fragmented sarcoplasmic reticulum preparation of goldfish acclimated to different temperatures. Membrane fluidity was estimated using the fluorescence polarization technique. There was considerable variation between preparations, but no consistent differences in fluidity were observed between 5- and 25°C-acclimated goldfish, fish species adapted over an evolutionary period to arctic or desert temperatures, and rat. The fatty acid composition of the sarcoplasmic reticulum preparations of differently acclimated goldfish showed differences in the proportion of mono- and polyunsaturated fatty acids while the proportion of saturated fatty acids remained relatively constant. However, the fatty acid composition of sarcoplasmic reticulum phosphoglycerides became more unsaturated in the order rat, desert pupfish, arctic sculpin, which correlates with their respective environmental or body temperature. It is concluded that differences in membrane components other than fatty acids are important in determining membrane dynamic structure. The inability to demonstrate homeoviscous adaptation in sarcoplasmic reticulum is supported by other evidence suggesting that functions of the sarcoplasmic reticulum that are measured in vitro are not affected by such modifications of their phosphoglyceride fatty acid composition as occur during thermal acclimation.     

Does diet-induced thermogenesis change the preferred ambient temperature of humans?

The thermal scores of nude resting subjects were followed for a period of 5 h. the subjects were sitting at rest from 0700 until 1200 hours at their previously determined preferred ambient temperature. Whether fasting or with a large (3.700 kJ) meal their comfort score remained the same and constant throughout the experiment. Their comfort sensation was not influenced by a significant, 20%, increase in metabolic rate produced by the meal, nor by the gradual rise in body temperature due to the diurnal rhythm.     

Energetics of tropical hibernation

In this field study, the energetic properties of tropical hibernation were investigated by measuring oxygen consumption and body temperature of the Malagasy primate Cheirogaleus medius in their natural hibernacula. These lemurs use tree holes with extremely varying insulation capacities as hibernacula. In poorly insulated tree holes, tree hole temperature and body temperature fluctuated strongly each day (between 12.8 and 34.4°C). The metabolic rate under these conditions also showed large daily fluctuations between about 29.0 ml O₂/h and 97.9 ml O₂/h in parallel with changes in body temperature. In well insulated tree holes in very large trees on the other hand, tree hole temperature and body temperature remained relatively constant at about 25°C. Lemurs hibernating in these tree holes showed a more constant metabolic rate at an intermediate level, but hibernation was interrupted by repeated arousals with peak metabolic rates up to 350 ml O₂/h. The occurrence of these spontaneous arousals proved that the ability for thermoregulation persists during hibernation. Arousals were energetically costly, but much less so than in temperate and arctic hibernators. Despite the decisive influence of tree hole properties on the pattern of body temperature and metabolic rate during hibernation, the choice of the hibernaculum does not seem to be of energetic importance. The overall energetic savings by tropical hibernation amounted to about 70% as compared to the active season (31.5 vs. 114.3 kJ/d). Therefore, tropical hibernation in C. medius is an effective, well-regulated adaptive response to survive unfavourable seasons.     

Comparative non-shivering thermogenesis in adjacent populations of the common spiny mouse (Acomys cahirinus) from opposite slopes: the effects of increasing salinity

We compared non-shivering thermogenesis between two adjacent populations of the common spiny mouse Acomys cahirinus from different habitats, in relation to increasing salinity. Individuals were captured from the north- and south-facing slopes of the same valley, that represent "Mediterranean" and "desert" habitats, respectively. We hypothesized that the two populations of mice would differ in their thermoregulatory capacities, reflecting their need to cope with the environmental stress in each habitat. We measured resting metabolic rate by recording oxygen consumption, body temperature and response to an injection of exogenous noradrenaline. Mice were maintained on diets with increasing levels of salt intake to examine their abilities to cope with increasing osmotic stress. Mice from north-facing slopes generally had a higher resting metabolic rate and a higher increase in oxygen consumption in response to noradrenaline than mice from south-facing slopes. Increasing salinity decreased resting metabolic rate values, body temperature, and oxygen consumption in response to noradrenaline in both populations, and diminished slope-dependant differences. We suggest that these differences could be a result of an ongoing adaptive process to different climatic conditions, typical of the Mediterranean region, that are a demonstrable example of evolution in action.     

锦鲫的摄食代谢与运动代谢及其相互影响

为了探讨锦鲫(Carassius auratus)幼鱼摄食后特殊动力作用(SDA)的变化特征及运动代谢与摄食代谢之间的相互影响,实验首先灌喂锦鲫4%体重的饲料和等体积的纤维素(湿重),测定灌喂前后的耗氧率;另设灌喂饲料、灌喂纤维素、空腹组(对照组)3个组,测定3组的临界游泳速度(Ucrit)和运动耗氧率(MO2);然后在70%、0%临界游泳速度下,分别测定饱足摄食组和空腹组的耗氧率。结果显示:1灌喂饲料后代谢率快速上升,达到峰值后又迅速下降,代谢时间较短,没有一个相对稳定的平台期,灌喂纤维素后代谢率没有显著性变化(P0.05)。提示锦鲫幼鱼的特殊动力作用功率曲线为一个典型的"三角型"模型,且在特殊动力作用总耗能中,生化特殊动力作用占特殊动力作用总耗能的绝大部分,而机械特殊动力作用只占特殊动力作用的极少部分。2锦鲫幼鱼在摄食后临界游泳速度显著下降(P0.05),代谢率显著升高(P0.05)。摄食后的运动过程中,代谢率从摄食开始到代谢率回落至空腹组代谢的标准误范围内的首个数据所对应的时间长度均为6.5 h,且摄食代谢无显著性差异。提示,对锦鲫幼鱼来说,摄食代谢降低了其运动能力,而运动代谢并没有影响摄食代谢。