Heart rates of adult red-spotted newts,Notophthalmus viridescens in air and submerged in normoxic and hypoxic water at different temperatures

• 1.1. Heart rates of adult aquatic red-spotted newts can be conveniently recorded using an impedance pneumograph.
• 2.2. Heart rates decrease linearly with decreasing temperature.
• 3.3. Submergence in normoxic and hypoxic water at 10°, 15°, and 20°C results in bradycardia which is more pronounced in hypoxic water.
• 4.4. At 5°C one newt exhibited the above pattern, but bradycardia was not exhibited by the other newt during normoxic submergence.
• 5.5. Diminishing heart rates are probably due to oxygen deficiency, not immersion alone.
• 6.6. Recovery from bradycardia in air is rapid and not linked with resumption of aerial breathing.

     

Physiological diving adaptations of the australian water skink Sphenomorphus quoyii

• 1.1. Both the small riparian skink Sphenomorphus quoyii and its completely terrestrial relative Ctenotus robustus respond to forced submergence with instantaneous bradycardia.
• 2.2. The strength of the bradycardia was affected by water temperature and fear. Dives into hot (30°C) water produced weak and erratic bradycardia compared to dives into cold (19.5°C) water. For S. quoyii the strongest bradycardia occurred when submergence took place in water at a lower temperature than the pre-dive body temperature.
• 3.3. Upon emergence both species of skink exhibited elevated heart rates and breathing rates while heating from 19.5 to 30°C, compared to heating at rest. The increased heart and breathing rates probably act to replenish depleted oxygen stores and remove any lactate. Increased heart and ventilation rates are not indicators of physiological thermoregulation in this case.
• 4.4. Both lizard species exhibited higher heart rates and ventilation frequencies during heating than cooling.
• 5.5. Compared to its terrestrial relative, S. quoyii does not appear to possess any major thermoregulatory, ventilatory or cardiovascular adaptations to diving. However, very small reptiles may be generally preadapted to use the water to avoid predators.

     

Examination of water balance and ionic regulation in the earthworm,Eisenia foetida

• 1.1. Weight change after submerging the earthworm into water varied remarkably according to the environmental humidity in which animals were placed before submergence.
• 2.2. Pretreatment with physiological saline solution before submergence in water gave stable values for the ionic concentrations of the body fluid.
• 3.3. Brain removal caused decrease of both sodium and chloride ion concentrations and increase of potassium ion concentration of the coelomic fluid when animals were submerged in water.
• 4.4. Although brain replacement failed, action of a brain hormone is suggested to regulate the decrease of both sodium and choride ions and increase of potassium ion of the coelomic fluid to normal level when animals were submerged in water.

     

The pattern and influential factors of aquatic pharyngeal movements of Trionyx sinensis

• 1.1. The pharyngeal movements of Trionyx sinensis during submersion where recorded with physiological instruments.
• 2.2. Anoxia or hypercapnia caused a marked increase in breathing rate of tested turtles during voluntary diving, and in anoxia there was a significant increase in the frequency of aquatic pharyngeal movements while hypercapnia had a slight or no effect on the frequency of these movements.
• 3.3. During voluntary diving when turtles could easily extend their heads out of water to breathe air, the frequency of rhythmic pharyngeal movements was lower; but during forced submersion, the frequency was higher and the movements were continuous.
• 4.4. The frequency increased more rapidly and greatly when turtles were in forced submersion than when they dived freely and could easily surface to breathe in N₂.
• 5.5. The frequency of pharyngeal movements of T. sinensis during diving in an aquarium with water depth of 30 or 45 cm was markedly higher than that at a water depth of 15 cm. Disturbing stimuli also influenced the aquatic rhythmic pharyngeal movements of T. sinensis.

     

Depressed baroreceptor-cardiac reflex sensitivity during simulated diving in ducks

• 1.1. The baroreceptor-cardiac reflex was examined in unanesthetized ducks at rest and during diving. In ducks breathing air an inverse relationship between mean arterial blood pressure and heart rate was observed over the pressure range from 80cm H₂O to 290cm H₂O.
• 2.2. Increases in pressure were obtained by bolus intravenous injection of phenylephrine (PE) while the hypotension was achieved by intravenous acetylcholine (ACh).
• 3.3. The inverse relation of blood pressure and heart rate was also observed in ducks without pharmacologic intervention.
• 4.4. The baroreceptor-cardiac reflex sensitivity was -3.13 beats/min/cm H₂O in non-diving ducks and fell to -0.96 beats/min/cm H₂O with PE and ACh derived data.
• 5.5. During diving the baroreceptor-cardiac reflex sensitivity was further reduced to —0.48beats/ min/cm H₂O.
• 6.6. This finding indicates that even during the pronounced bradycardia of diving baroreceptor stimulation continues to influence heart rate.

     

Heart rate and blood pressure in bullfrogs during prolonged maintenance in water at low temperature

• 1.1. Bullfrogs were maintained in air-saturated water at 4°C under an 8:16hr, light:dark, photoperiod for 50 days from December to February.
• 2.2. Heart rates and mean arterial pressures from these submerged frogs remained stable throughout the entire period in the cold. The slow heart rates that were observed appeared to result from a combination of low temperature and submergence. No indication of torpor was observed in any of the animals.
• 3.3. These findings demonstrate that the cardiovascular system of bullfrogs apparently retains normal regulatory function when these animals are maintained under temperature and photoperiod conditions analogous to those found during overwintering.

     

The influence of aerial exposure on gas exchange and cardiac activity in the shore crab,Carcinus maenas (L.)

• 1.1. The cardiovascular physiology of adult Carcinus maenas (L.) emerging into air has been investigated at three different air temperatures.
• 2.2. Transition from seawater to air or vice versa triggered transient increases in cardiac and locomotor activity.
• 3.3. However, crabs became inactive 5–10 min after emerging from seawater (15°C) into air at the same temperature (15°C) or at lower temperatures (12–13°C) and heart rate fell.
• 4.4. At higher air temperatures (18–20°C) heart rate rose but to a lesser extent than predicted from aquatic Q₁₀ heart-rate values.
• 5.5. Crabs were again quiescent in aerial conditions.
• 6.6. Mean arterial oxygen tension (Pa_o2) was ~ 74 mmHg in submerged crabs but fell to ~ 38 mmHg in air while mean arterial carbon dioxide tension (Pa_o2) increased from 1 to 4 mmHg resulting in respiratory acidosis.
• 7.7. A model of gill function is proposed to explain the development of internal hypoxia in air.
• 8.8. The results are discussed in relation to the distribution of adult and juvenile C. maenas in situ.

     

Respiration in the eastern water dragon,Physignathus lesueurii (agamidae)

• 1.1. Some aspects of the gas exchange system of a diving lizard, Physignathus lesuewii were studied.
• 2.2. Breathing patterns were analysed.
• 3.3. Breathing rate increases logarithmically with temperature and Q₁₀ = 1.8. LogBR = −0.237 + 0.0256 T.
• 4.4. Gas tensions in lung air and arterial and venous blood were measured. Arterial pH declines with increasing temperature.
• 5.5. Temperature has a marked effect on oxygen affinity of the blood (ΔH = −10.1 kcal mol⁻). A Bohr effect was also noted.
• 6.6. CO₂ equilibrium curves were drawn.
• 7.7. The results are considered with a view to anticipating the efficiency of the gas exchange system of this species under conditions of variable temperature and during diving.

     

Amino acid activating enzymes in Sarcophaga bullata

• 1.1. The fat-body soluble fraction from two-day Sarcophaga bullata larvae contain amino acid activating enzymes for nineteen amino acids.
• 2.2. The level of activity varies with the amino acid substrate.
• 3.3. The total ³²PP-ATP exchange activity of the pupae decreased with age for the first 6 days, then increased to a maximum one or two days prior to emergence of the adults.
• 4.4. The free amino acid concentration in the pupae decreased during the period when the amino acid activating activity increased.

     

Stratophenetic analysis of avascular necrosis in turtles: Affirmation of the decompression syndrome hypothesis

• 1.1. The decompression syndrome hypothesis, as an explanation of the etiology of avascular necrosis, is further substantiated through analysis of its occurrence in turtles.
• 2.2. No examples were identified in terrestrial or aquatic forms diving to depths insufficient for development of decompression syndrome.
• 3.3. The “population” frequency of avascular necrosis has substantially diminished over geologic time.
• 4.4. A frequent occurrence in Cretaceous marine turtles, it is only rarely observed in specimens younger than Miocene age.
• 5.5. Evolution of physiologic and/or behavioral protective mechanisms appears to be responsible for reduced susceptibility to the underlying decompression syndrome.

     

Energy difference in lipid and glycogen metabolism of healthy and iridescent virus-infected Heliothis zea (Boddie)

• 1.1. Heliothis zea (Boddie) larvae infected with irridescent virus (IV) showed rapid cell dissolution in the fat bodies.
• 2.2. Fatty acid accumulation in healthy H. zea was significantly greater (P < 0.001) than in IV-infected larvae.
• 3.3. Healthy and IV-infected larvae accumulated glycogen at a rate of 3.86 cal and 0.19 cal/day/insect, respectively.
• 4.4. Total protein of healthy and IV-infected larvae showed no significant difference with time.

     

Relationship between brain trehalase activity and trehalosema during direct and diapausing development in Pieris brassicae

• 1.1. Brain trehalase specific activity and trehalosemia were measured during the end of the developmental life cycle in non-diapausing and diapausing insects.
• 2.2. During non-diapausing development, trehalosemia reached maximum values at the beginning of pupal life. Then a constant decrease was observed up to the end of adult life.
• 3.3. The specific activity of brain trehalase was maximum when the insects were in active feeding periods, minimum activity appearing during moulting phases.
• 4.4. During diapausing development, trehalosemia was very high at the beginning of pupal life, particularly when insects were exposed to wintering conditions.
• 5.5. When diapause was broken, trehalosemia fell, announcing adult emergence.
• 6.6. Brain trehalase activity showed the same qualitative variations as in non-diapausing larvae, but with rather lower values.
• 7.7. During pupal life, brain trehalase activity decreased markedly during the long period necessary to obtain diapause breakdown.
• 8.8. Wintering conditions allow a progressive increase of brain trehalase activity, which preceded the fall of trehalosemia.

     

Effect of exposure to atmospheric air on blood glucose and lactate concentrations in two crustacean species: A role of the Crustacean hyperglycemic hormone (CHH)

• 1.1. In intact (control) crabs (Carcinus maenas) and crayfish (Orconectes limosus) a significant (P < 0.01) increase in both glucose and lactate concentrations in the blood was observed after exposure to air. Such changes were not observed in either eyestalk-less or eyestalk-less and saline injected animals (P > 0.05).
• 2.2. Injections of Crustacean hyperglycemie hormone (CHH) into eyestalk-less animals before exposure to air were able to reverse the effects of eyestalk ablation, i.e., significant increases (P < 0.01) in blood glucose and lactate could again be observed.
• 3.3. Significant hyperglycemia (P < 0.01), but no changes in lactate concentration (P > 0.05), was observed after injection of CHH in eyestalk-less submerged animals.
• 4.4. These results suggest that the increase in glycolysis after air exposure is facilitated by CHH, possibly by increased substrate availability due to glycogen degradation.

     

Digestive protease,lipase and amylase activities in stage i larvae of the american lobster,Homarus americanus

• 1.1. Digestive protease, lipase, and amylase of Stage I larvae of the American lobster Homarus americanus are characterized.
• 2.2. A sensitive method for detection of crustacean lipase was developed using an latroscan which combines thin-layer chromatography and flame ionization detection to quantify free fatty acids generated by lipase digestion.
• 3.3. pH optima of the three enzymes occurred at or near the pH of gastric fluid.
• 4.4. A time course study demonstrated slight increases in protease and amylase activities during the first larval stage, regardless of whether the lobsters were fed or not, whereas lipase activity was constant.

     

Oxidants and antioxidants in aquatic animals

• 1.1. Oxidative stress, potentially, is experienced by all aerobic life when antioxidant defenses are overcome by prooxidant forces, and is the basis of many physiological abberations.
• 2.2. Environmental contaminants may enhance oxidative stress in aquatic organisms, e.g. highly elevated rates of ideopathic lesions and neoplasia among fish inhabiting polluted environments is increasingly related to oxidative stress associated with environmental pollution.
• 3.3. Metabolism of redox cycling xenobiotics in aquatic organisms is very similar to that of mammals suggesting similarities in the health consequences of exposure to such compounds.
• 4.4. The expression of specific lesions known to arise specifically from oxidative stress, e.g. lipid peroxidation, oxidized bases in DNA and accumulation of lipofuscin pigments are present in many aquatic animals exposed to contaminants.
• 5.5. Aquatic organisms contain the major antioxidant enzymes SOD, catalase and glutathione peroxidase, albeit there are marked quantitative differences among the various species reported.

     

Cardiac responses of the anurans,Bufo bufo and Rana pipiens,during behavioural arousal and fright

• 1.1. Electrocardiograms (ECGs) were recorded from B. bufo and R. pipiens whilst behaviourally aroused and frightened.
• 2.2. A tachycardia was exhibited in both states, though in fright it was preceded by a “missed” beat.
• 3.3. The difference between these responses and those of other vertebrates was discussed in relation to the amphibious habit.
• 4.4. It is suggested that the cardiac responses of diving, fright and arousal may have a common evolutionary origin.

     

Alterations in proteases,protease inhibitors and ecdysone levels: a profile of stress in insects

• 1.1. A comparison of proteolytic and protease inhibitory activity, and ecdysteroid levels in body fluids was made between normal larvae of the flesh fly, Sarcophaga bullata, and those that had been water-stressed for two days.
• 2.2. The course of proteolytic activity in water stressed flies decreases 6 hr after beginning the experiment and remains low in comparison with control flies.
• 3.3. The course of protease inhibitors exhibits a mirror image pattern to proteases.
• 4.4. Ecdysteroid pattern shows two peaks in control animals: minor at 24 hr and major at pupariation, in experimental animals: at 1 hr, at 6 hr and at white pupal stage.

     

Respiratory mechanisms and metabolic adaptations of an intertidal crab,Chasmagnathus granulata (Dana, 1851)

• 1.1. The ventilatory mechanism, gill area, sites of oxygen uptake, oxygen consumption and activity of a crab from south Brazil, Chasmagnathus granulata, were investigated.
• 2.2. The oxygen uptake seems to be restricted to the gill lamellae.
• 3.3. The gill area varies with the wet body weight, being relatively higher in smaller animals. There is not a significative reduction of the gill area in relation to species of the infralittoral zone.
• 4.4. C. granulata presents a mechanism for recirculating the water of its branchial chamber when exposed to atmospheric air.
• 5.5. The oxygen consumption and activity are reduced when the animals are exposed to atmospheric air. The reduction in the oxygen consumption may be related to the poorly adapted respiratory system, while the decrease in activity may be a mechanism for saving energy during this hypoxic period.

     

Growth and hemolymph trehalose levels of Heliothis zea larvae fed diets containing various sugars

• 1.1. The amount of sugar required for growth of Heliothis zea larvae on a chemically defined diet was determined.
• 2.2. Larvae grew well on fructose, galactose, sucrose, trehalose and raffinose diets but not on diets containing more than 0.5% glucose.
• 3.3. A starch diet did not promote rapid larval growth.
• 4.4. Hemolymph trehalose levels in 12-day-old larvae ranged from none to 45μmoles/ml.
• 5.5. A method for analysis of hemolymph trehalose by gas chromatography is described.