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.

     

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.

     

Effect of temperature and diet on polyamine concentrations of the European sea bass (Dicentrarchus labrax L.)

• 1.1. A fall of environmental temperature causes a decrease in total polyamine concentrations of heart, red and white muscles of sea bass fed on a diet containing 70% herring meal (diet S).
• 2.2. When sea bass was fed with a diet partially replaced by casein (diet A), an increase of total polyamine concentration in liver and heart was observed at a lower temperature.
• 3.3. In all tissues studied an increase of putrescine concentrations and a parallel decrease of spermidine and spermidine levels were found for both groups S and A of sea bass when the temperature was lowered.
• 4.4. In general concentrations of putrescine, spermidine and spermine were considerably higher in group A when the temperature was lowered.

     

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.

     

Cardiac responses of larval and adult tiger salamanders to submergence and emergence

• 1.1. The ECG of aquatic Amhystoma tigrinum from the Colorado Rocky Mountains was recorded while the animals submerged and emerged in water. Older larvae and metamorphosed adults were compared.
• 2.2. Free-swimming animals of both types showed slight emergence tachycardia when taking a “gulp” of air.
• 3.3. Preventing access to air for 30 min or more resulted in a slight bradycardia in larvae. Some adults responded with increased, others with decreased, heart rate depending on their level of excitement.
• 4.4. Restraining the animals before forced submergence caused a greater bradycardia than when unrestrained.
• 5.5. Low dissolved oxygen accentuated the cardiac responses of larvae to submergence but not in adults.
• 6.6. Atropine only partially blocked the diving responses of both forms.
• 7.7. The degree of submergence bradycardia seems to be a function of the ability to extract oxygen from water. It probably is not an adaptation to diving in these forms. Instead the submerged heart rate in these predominantly aquatic salamanders may be the “normal” rate with emergence tachycardias for breaths of air.

     

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.

     

The energetics of shedding: Energy content of snake skin

• 1.1. The weight and energy content of sloughed skins of 92 individual snakes of 22 different species in three families were measured.
• 2.2. Weight and total energy content of shed skins were highly correlated with body weight.
• 3.3. The heat of combustion (kJ/g) of sloughed skins varied significantly among families and was higher in species having unkeeled scales than in those with keeled scales.
• 4.4. The presence of keels significantly affected weight of skins, even when skin weight is adjusted for covariance with body weight.
• 5.5. Neither body weight nor ambient temperature significantly affected the heat of combustion of sloughed skins.
• 6.6. The energy content of shed skin, expressed as a proportion of daily metabolism, decreased with ambient temperature, but the effect is minimized in large snakes.
• 7.7. Small snakes expended relatively less energy in sloughed skins than large snakes when the expenditure is expressed in terms of total daily metabolized energy.

     

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.

     

Novel tetraamines,pentaamines and hexaamines in sea urchin,sea cucumber,sea squirt and bivalves

• 1.1. Polyamines were extracted from the guts and ovaries of the sea urchin Anthocidoris crassispina, and the guts and flesh of the sea cucumber Stichopus japonicus and the sea squirt Halocynthia roretzi, the oyster Crassostrea gigas and the short-necked clam Tapes philippinarum, and analyzed by ion-exchange high-performance liquid chromatography and gas chromatography-mass spectrometry.
• 2.2. Norspermidine and norspermine as well as putrescine, cadaverine, spermidine, spermine and agmatine were the ubiquitous polyamines in these invertebrates. These results suggest the widespread distribution of norspermidine and norspermine in invertebrates.
• 3.3. Thermopentamine, thermohexamine and homothermohexamine were found in the sea urchin. This in the first report on the occurence of thermopentamine and hexaamine in invertebrates.
• 4.4. Homospermidine, canavalmine, aminopropylhomospermidine, homospermine, caldopentamine, homocaldopentamine and aminopropylcanavalmine were found in the sea cucumber. Homospermidine, aminopropylhomospermidine and homospermine were found in the squirt. This is the first report on the occurence of canavalmine, aminopropylhomospermidine, homospermine, homocaldopentamine and aminopropylcanavalmine in invertebrates.

     

A test of the thermal coadaptation hypothesis with black rat snakes (Elaphe obsoleta) and northern water snakes (Nerodia sipedon)

• 1.The thermal coadaptation hypothesis predicts that (1) ectotherms experiencing a narrow range of body temperatures in the wild will evolve to perform well over a narrow range of body temperatures and that (2) the optimal temperature for performance will be equal to the preferred body temperature of the species.
• 2.We tested the predictions of the thermal coadaptation hypothesis with black rat snakes (Elaphe obsoleta) and northern water snakes (Nerodia sipedon) because black rat snakes experience lower and more variable body temperatures than northern water snakes at our study site.
• 3.We measured swimming speed, tongue-flicking speed, and striking speed in black rat snakes, and swimming speed and tongue-flicking speed in northern water snakes.
• 4.Adult water snakes generally had narrower performance breadths and higher optimum performance temperatures than adult black rat snakes.
• 5.Performance breadths were the same for swimming, tongue flicking, and striking within adult black rat snakes, but performance optima for these behaviours differed significantly. Performance breadths differed and performance optima were the same for swimming and tongue flicking within adult northern water snakes.
• 6.The relative swimming performance of neonates of the two species was similar in breadth to that of adults, but the thermal optimum for neonate black rat snakes was higher than that of adults.
• 7.Overall, our results provided support for the thermal coadaptation hypothesis.

     

A halogenated amino acid-containing sperm activating peptide and its related peptides isolated from the egg jelly of sea urchins,Tripneustes gratilla,Pseudoboletia maculata,Strongylocentrotus nudus,Echinometra mathaei and Heterocentrotus mammillatus

• 1.1. Twenty-eight peptides were isolated from the egg jelly of sea urchins, Tripneustes gratilla, Pseudoboletia maculata, Strongylocentrotus nudus, Echinometra mathaei (type A and B) and Heterocentrotus mammillatus and their amino acid sequences were determined.
• 2.2. Two of the peptides obtained from T. gratilla egg jelly possessed a bromophenylalanine (Br-Phe) residue in their sequences (Gly-(Br-Phe)-Asn-Leu-Asn-Gly-Gly-Gly-Val-Gly and Gly-(Br-Phe)-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly).
• 3.3. All of the peptides elevated cyclic GMP concentrations in the spermatozoa of the respective sea urchin and caused a shift in the apparent mol. wt of a major sperm protein of the respective sea urchin.
• 4.4. They stimulated respiration rates of the spermatozoa of Hemicentrotus pulcherrimus as well as their own species.
• 5.5. One-half maximal concentrations of the peptides for respiratory stimulation of H. pulcherrimus spermatozoa were between 10⁻¹¹ M and 10⁻⁹ M except a methionine-containing peptide which was about 10⁻⁷ M.

     

Time related changes in the free amino acid pool of the sea anemone,Bunodosoma cavernata,during salinity stress

• 1.1. The sea anemone, Bunodosoma cavernata, is a relatively eurybaline cnidarian tolerating salinities from 12 to 40%.
• 2.2. Taurine, glutamic acid and aspartic acid all showed some increases with increased salinity.
• 3.3. The amino acid showing the greatest accumulation under high salinity conditions was β-alanine which increased 28-fold from 1.5 to 41.9 μmol/g dry weight when salinity was raised from 26 to 40%.
• 4.4. When B. cavernata was subjected to increased salinity, β-alanine was rapidly accumulated and reached maximum levels within 4 days.
• 5.5. When salinity was dropped from 36 to 26%0, β-alanine concentrations dropped from 15 to 2 μmol/g dry weight in 2 days.

     

Body temperature relationships in the lined snake,Tropidoclonion lineatum

• 1.1. Body temperatures of 69 adult lined snakes collected in the field were recorded along with associated air and substrate temperatures.
• 2.2. There was no difference between the mean body temperature of males and females or between gravid and non-gravid individuals.
• 3.3. Body temperatures differed significantly from either air or substrate temperatures.
• 4.4. Lined snakes appear to maintain an activity temperature range by use of selected microhabitats.

     

Fluxes of dissolved amino acids between sea water and Echinaster

• 1.1. Measurement of free amino acid (primary amine) influx and efflux into the starfish, Echinaster, were accomplished utilizing improved methods of sea water purification and analysis.
• 2.2. Specimens placed in amino acid depleted sea water (5 × 10⁻⁸ M) demonstrated net release as measured with the fluorescamine method. Similarly, specimens placed in the same water to which amino acid mixtures had been reintroduced to normal levels demonstrated net uptake.
• 3.3. A mathematical model indicated an equilibrium amino acid concentration (when influx equals efflux) of 5.26 × 10⁻⁷ M, or about one fourth the level of natural sea water.
• 4.4. Since at normal environmental levels (20.65 × 10⁻⁷ M) net flux is inward by a ratio of nearly 4-1, it is concluded that the previous suggestions of some workers that such would not be the case for marine invertebrates are no longer valid.
• 5.5. The net uptake of amino acid from environmental levels would account for 5.67% of the measured total respiration if all were being metabolized.
• 6.6. This figure appears to be in line with the previously developed hypothesis that the epidermis largely obtains its nutrition directly from the environment. However, the real benefit of the uptake mechanism may be to prevent loss of the body amino acid pools.

     

Occurrence of d-alanine in the eggs and the developing embryo of the sea urchin Paracentrotus lividus

• 1.1. d-Alanine has been found in appreciable amounts in the eggs and embryos of the sea urchin Paracentrotus lividus.
• 2.2. The content of d-alanine, expressed as pmol/egg or embryo, is 1.32 in the egg, 0.81 in the blastula, 0.54 in the gastrula and 0.60 in the pluteus.
• 3.3. The percentage of d-alanine with respect to the total alanine (d + l) decreases during embryonic development.
• 4.4. d-Amino acid oxidase, d-alanine transaminase and d-alanine racemase activities were found neither in eggs nor in embryos.
• 5.5. Therefore, it does not appear likely that d-alanine is subject to oxidative metabolism.
• 6.6. The decrease in this d-amino acid during development may be due to its utilization in the synthesis of a more complex molecule.

     

Microheterogeneity of late histones in larval stages of sea urchin development

• 1.1. The total histone complement of early plutei were compared with that of intermediate and late larvae of the sea urchin Tetrapygus niger.
• 2.2. Electrophoretic comparison indicates that there are quantitative and qualitative shifts of the five classes throughout late larval development.
• 3.3. The strong similarity in the amino acid composition of total histones isolated from early, intermediate and late plutei indicates that the observed electrophoretic heterogeneity is due to post-translational modifications.

     

Short-term osmotic responses of cells and tissues of the sea anemone,Condylactis gigantea

• 1.1. Cells of tentacles and body wall of the sea anemone Condylactis gigantea behaved as simple osmometers during 5hr exposure to 50, 67, 83, 100 and 125% sea-water.
• 2.2. All intracellular water appeared to be osmotically active.
• 3.3. Cell sodium, chloride and total osmolyte content remained invariable, with taurine decreasing and potassium increasing as sea-water concentration was reduced.
• 4.4. Tissues, as a whole, exhibited a pseudoregulatory response to changes in salinity as the large and osmotically inert extracellular space buffered volume changes to a considerable extent.

     

Adaptation of rainbow trout (Salmo gairdnerii) to sea water: Changes in calcitonin levels

• 1.1. The calcitonin content of the ultimobranchial body (UBB) and plasma levels of calcitonin, calcium and phosphate were measured in rainbow trout (Salmo gairdnerii) following their transfer from fresh to sea water.
• 2.2. The plasma calcium level remained unchanged throughout the experiment while the UBB calcitonin content, plasma calcitonin and plasma phosphate rose significantly during the hours immediately following transfer.
• 3.3. The levels of all three subsequently fall so that, 8–15 days later, a new equilibrium was established with lower than control (fresh water) levels of UBB calcitonin, plasma calcitonin and plasma phosphate.
• 4.4. It would appear, from these data, that calcitonin plays some part in the endocrine regulation of sea water transfer.

     

Fate of ingested leucine and glucose in the sea star,Asterias rubens,during its annual reproductive cycle

• 1.1. The distribution of radiolabel from L-leucine [¹⁴C-UL] and D-glucose [¹⁴C-UL] was measured in the sea star Asterias rubens at 1, 6 and 24 hr after oral administration.
• 2.2. Incorporation of the label from both compounds was observed in pyloric caeca, coelomocytes and ovaries even after an incubation time of 1 hr.
• 3.3. Highest incorporation from both precursors was found in proteins, while substantial radioactivity was present in the amino acids, organic acids and neutral components. Lipids were hardly labelled from leucine and only slightly from glucose.
• 4.4. Radioactivity in proteins and lipids increased with increasing incubation time. No significant differences were found in the distribution patterns of radiolabel during the reproductive cycle.
• 5.5. The data obtained are discussed in terms of current knowledge on the translocation of nutrients in echinoderms.

     

Pigmentation in the sea anemone Corynactis californica

• 1.1. There is great variability in the color of the sea anemone, Corynactis californica (Calgren, 1936). Studies of the columns of seven different color varieties showed no major differences in type or concentration of carotenoids. An astaxanthin ester and an unidentified carotene were isolated.
• 2.2. The isolated carotenoids do not appear to be responsible for the variety of colors in Corynactis.
• 3.3. The color variation of C. californica is more probably dependent on an unidentified, water-soluble pigment similar to a bile-like pigment, calliactine, isolated from the sea anemone, Sagartia parasitica (Couch, 1838).