Aerial respiration in the semaphore crab,Heloecius cordiformis,with or without branchial water

• 1.1. Semaphore crabs (Heloecius cordiformis) are active in air at low tide. Their branchial chambers are lined with a vascular epithelium and are expanded above the gills (five pairs) to form air cavities which could function as lungs. Water is continuously circulated over the gills.
• 2.2. The relative contribution made by the gills and lungs to gas exchange in semaphore crabs active in air and circulating branchial water, was determined by measuring oxygen consumption (at 25°C) in crabs with and without branchial water, and in crabs with their lungs subsequently occluded.
• 3.3. Activity levels and VO₂ were unaffected by the absence of branchial water.
• 4.4. With their lungs occluded, VO₂ dropped (on average) by 61% in crabs with branchial water (i.e. gills still functional) and by 81% in crabs without branchial water (gill function impaired).
• 5.5. It is concluded that semaphore crabs are obligate air breathers while active on land, despite carrying water within their branchial chambers. Lung development and gill reduction in land crabs is discussed briefly in relation to “terrestriality”.

     

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.

     

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.

     

Oxygen binding by the hemocyanin of Busycon canaliculatum

• 1.1. This study examined the effect of the monoamines dopamine and octopamine, as well as tyrosine on the oxygen affinity and cooperativity of oxygen binding by the hemocyanin of the marine gastropod Busycon canaliculatum. The effect of temperature on hemocyanin oxygen affinity was also examined.
• 2.2. Freezing Busycon hemocyanin did not affect the binding of oxygen.
• 3.3. Dopamine, octopamine and tyrosine had no significant effect on the oxygen affinity or cooperativity of oxygen binding by the hemocyanin of B. canaliculatum.
• 4.4. It was concluded that Busycon hemocyanin either has no binding sites for the two monoamines or for tyrosine, or that binding of the molecules has no functional significance.
• 5.5. Both temperature sensitivity and affinity of hemocyanin-oxygen binding were similar to values previously reported for hemocyanin of Busycon from other localities.

     

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.

     

A fetal-maternal shift in the oxygen equilibrium of hemoglobin from the viviparous caecilian,Typhlonectes compressicauda

• 1. The equilibria and kinetics of oxygen binding by blood and hemoglobin from adult and fetal caecilians,Typhlonectes compressicauda, have been measured.
• 2. The oxygen affinity of fetal blood is higher than that of adult blood.
• 3. Electrophoresis of adult and fetal hemoglobins suggests that they may be identical: a major and minor component occurs in each.
• 4. Adult and fetal hemoglobins have identical oxygen equilibria. Stripped hemoglobins have a high oxygen affinity and no Bohr effect between pH 6.5 and 10.0. An “acid”, reversed Bohr effect is present below pH 6.5. The addition of 1 mM ATP reduces the oxygen affinity markedly and produces a moderate, normal Bohr effect.
• 5. The major nucleoside triphosphate in fetal and adult erythrocytes is adenosine triphosphate: about 10% of the nucleoside triphosphates is guanosine triphosphate. Adult erythrocytes contain 3 times as much ATP as do the fetal erythrocytes.
• 6. The fetal to maternal shift in the oxygen equilibrium is mediated entirely by the difference in ATP content of the maternal and fetal red blood cells.

     

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.

     

Oxygen binding of intact coelomic cells and extracted hemoglobin of the echiuran Urechis caupo

• 1.1. The oxygen affinity of Urechis caupo coelomic cells is the same in normoxic and in hypoxic animals. There is no Bohr effect between pH 6.8 and 8.0.
• 2.2. The oxygen affinity of intact coelomic cells is the same as that of extracted, stripped hemoglobin. The oxygen binding properties of stripped hemoglobin are not affected by 1 mM ATP, IMP, or hydrogen ions between pH 6.8 and 8.0, nor do they clearly show cooperativity. The heat of oxygenation. ΔH, = −13.1 kcal/mol between 10 and 25 C.
• 3.3. Although U. caupo coelomic cell hemoglobin is tetrameric and intracellular, it apparently exhibits neither heterotropic nor homotropic interactions.

     

Functional properties of the two major hemoglobin components from Leporinus friderici (Pisces)

• 1.1. The hemoglobins of Leporinus friderici were separated by liquid chromatography on DEAE-Sepharose in order to isolate the two major electrophoretic components.
• 2.2. The chromatographic fraction I (electrophoretically slow anodic) showed no Bohr effect and no nucleoside triphosphate modulation.
• 3.3. The chromatographic fraction III (electrophoretically fast anodic) showed a normal Bohr effect and addition of nucleoside triphosphate decreased oxygen affinity but did not alter the Bohr effect.
• 4.4. The whole hemolysate showed a normal Bohr effect and phosphate modulation altered both Bohr effect and oxygen affinity.
• 5.5. No or little difference between the effect of adenosine or guanosine triphosphates on hemoglobin function was observed.

     

Functional studies on the separated hemoglobin components of an air-breathing catfish,Hoplosternum littorale (Hancock)

• 1. The two hemoglobins, Hb I and II, of the obligate air-breathing catfish,Hoplosternum littorale have been isolated.
• 2. The unfractionated stripped hemoglobin has a high oxygen affinity, a normal alkaline Bohr effect, and a Root effect.
• 3. Both the Bohr and Root effects are enhanced by 1 mM ATP.
• 4. Stripped Hb I has a relatively high oxygen affinity, a reversed Bohr effect between pH 6.0 and 8.0 (Δlog P₅₀2DpH> 0), but no Root effect. Addition of 1 mM ATP to Hb I causes a marked reduction in the oxygen affinity, a change to a normal alkaline Bohr effect (Δlog P₅₀ΔpH< 0), but no Root effect.
• 5. Stripped Hb II has a lower oxygen affinity at low pH and a higher oxygen affinity at high pH than does Hb I. Hb II shows a large alkaline Bohr effect which is only slightly increased by 1 mM ATP and a Root effect at low pH which is enhanced by 1 mM ATP.
• 6. The observed rates of O₂ dissociation and of CO combination with Hbs I and II show differences which parallel those observed in the oxygen equilibrium measurements.

     

Characterization of the vasoactive intestinal polypeptide (VIP) in the gut of fishes

• 1.1. The presence of VIP was investigated in the dogfish, Scyliorhinus canicula, the ballanwrasse. Lubrus berggylta and the bib. Trisopterus luscus, using a specific radioreceptorassay.
• 2.2. Pure porcine VIP and gut extracts of fishes yielded similar dilution curves.
• 3.3. In the dogfish, the highest concentration of VIP was found in the hindgut. In contrast, in the two teleostei studied, the highest levels of VIP were in the first part of the gut.
• 4.4. The biologically active VIP measured by radioreceptorassay correlated well with the molecule determined using a specific radioimmunoassay.
• 5.5. Our results support the hypothesis of the appearance of VIP early in evolution.

     

Correlation between body color and behavior in the upside-down catfish,Synodontis nigriventris

• 1.1. Unlike common fishes and as its Latin name implies, the upside-down catfish, Synodontis nigriventris, possesses dark ventral skin. Microscopic observation reveals that melanophores are present on both the ventral and the dorsal skin but differ in size and density of distribution.
• 2.2. The darkness of both sides of the fish changes in accordance with that of the background.
• 3.3. At night, the fish are very active and the body becomes pale. The change in color is more noticeable in the dorsal than the ventral skin.
• 4.4. When melatonin was added to the bathing water, the fish became pale and swam restlessly even when they were exposed to the black background.
• 5.5. It was found that the catfish preferred the black background to the white one.

     

Functional studies on the single component hemoglobin from an Amazon knife fish,Sternopygus macrurus

• 1. The whole blood of the non-air-breathing gymnotid teleost,Sternopygus macrurus, is half-saturated with oxygen at 5.2 mm Hg (apparent value) at 30°C in the absence of CO₂. Addition of 5.6% CO₂ causes the apparentP₅₀ value to increase over 3-fold.
• 2. The oxygen affinity of the stripped single-component hemoglobin at 20°C increases about 20-fold between pH 5.8 and 8.6 in the absence of ATP. This difference increases to 100-fold in the presence of 1 mM ATP.
• 3. A substantial Root effect is present: the stripped hemoglobin is only 70% saturated with O₂ at pH less than 6 when equilibrated with air.
• 4. The value of the Hill coefficient,n, is maximal near pH 7.0–7.5, and approaches 1.0 at high pH. The value is about 1.5 at low pH in the absence of ATP and 1.0 in the presence of 1 mM ATP.
• 5. The O₂ dissociation kinetics are heterogeneous at all pH values but most heterogeneous at low pH. The rate increases substantially as the pH decreases.
• 6. The CO combination kinetics as measured by the stopped flow technique are largely homogeneous except at high pH, but the CO combination kinetics after flash photolysis are markedly heterogeneous.

     

Seasonal adaptations in oxygen transport in brown trout Salmo trutta fario

• 1.1. Blood parameters determining oxygen capacity and oxygen affinity were measured in brown trout at different times of the year.
• 2.2. Haematological data indicate a slight decrease in blood oxygen capacity during the warm seasons. 3. Oxygen affinity increases significantly during summer and decreases in winter.
• 3.4. The changes in P₅₀ exhibited a positive correlation with the amount of anodic haemoglobin components, and a negative correlation with the amount of cathodic haemoglobin components.
• 4.5. The changes observed in the [ATP]/[Hb] molar ratio were not correlated with oxygen affinity and gave values near one.
• 5.6. We conclude that the oxygen affinity increase could be a physiological adaptation to oxygen transport during the wanner period. A possible mechanism is discussed.

     

Distribution of free l-histidine and related dipeptides in the muscle of fresh-water fishes

• 1.1. From the muscle of 20 species of fresh-water fishes, l-histidine, carnosine, anserine, and balenine were analysed by high-performance liquid chromatography.
• 2.2. All cyprinoidei fishes contained significant amount of l-histidine and trace of dipeptides.
• 3.3. High concentration of anserine was found in salmonoidei fishes, irrespective of salmonidae and osmeridae.
• 4.4. Two species of anguilloidei contained large amount of carnosine, small of l-histidine, and determinable of anserine and balenine.
• 5.5. Only trace amounts of these compounds were found in percoidei fishes.
• 6.6. The levels of these compounds represented no large difference among species belonging to sub-order group as well as family.

     

Variations in response to environmental hypoxia of different colour forms of the shore crab,Carcinus maenas

• 1.1. The oxygen consumption of red and green Carcinus in normoxic and hypoxic sea water was determined, using an oxygen electrode in a sealed respirometer.
• 2.2. The red crabs had significantly higher “excited” oxygen uptake rates and a lower ability to compensate for hypoxia than the green crabs.
• 3.3. Red Carcinus display an emersion response to declining oxygen at lower oxygen tensions than the green crabs.
• 4.4. Mortality of red crabs exposed to prolonged anoxia was much greater.
• 5.5. The relationship of these findings to the zonation of the two colour forms on the shore is discussed.

     

Acclimation to hypoxic water in facultative air-breathing fish: Blood oxygen affinity and allosteric effectors

• 1. Blood oxygen affinities, erythrocytic nucleoside triphosphate concentrations (NTP) and other hematological parameters were measured in facultative air-breathing fish from the Amazon after acclimation to well-aerated (“normoxic”) and hypoxic water (PO₂ = 125–135 and 20–25 mm, respectively).
• 2. In the armored catfishHypostomus sp. andPterygoplichthys sp., hypoxia induces intermittent surfacing to gulp air and results in lower NTP levels, chiefly through significant decreases in guanosine triphosphate (GTP). The subsequent increases in blood O₂ affinity appear adaptive to lowered time average internal O₂ tensions. No similar changes were seen in the ellSynbranchus which breathes air almost continuously when kept in hypoxic water.
• 3. The results are discussed in terms of their adaptive significance, and compared with data on temperate fish.

     

Ventilatory rate in the butterfish (Pholis gunnellus) as a consequence of temperature and previous emersion

• 1.1. Observation of ventilation in immersed Pholis gunnellus showed a linear relationship between ventilatory rate and temperature between 8 and 20°C.
• 2.2. At 13°C and after 30 min emersion, ventilatory rate was initially lower than prior to emersion, providing evidence of adequate uptake of O₂ for standard metabolism during the emersion period.
• 3.3. This species has a laterally elongate body form with reduced scales and extensive mucus secretion.
• 4.4. During emersion, gaping behaviour probably exposes the gills and extensively vascularised oesophageal regions to air.
• 5.5. These are considered to be morphological and behavioural adaptations by P. gunnellus, to aerial respiration in the intertidal habitats occupied by this species.

     

Aerobic and anaerobic respiration of adult Artemia salina L., acclimated to different oxygen concentrations

• 1.1. Adult male Atremia salina L. were acclimated to five different oxygen concentrations and their respiration in response to environmental oxygen concentrations was determined.
• 2.2. Anemia is a respiratory regulator over a wide range of partial O₂ pressures. A critical oxygen tension exists and decreases with acclimation to lower pO₂.
• 3.3. Hypoxic conditions induce the production of hemoglobin III.
• 4.4. Lactic acid is produced during anaerobiosis.
• 5.5. Production of Hb III and lactic acid, being inversely proportional to the acclimation level, has to be considered as a long term or short term adaptation to hypoxic conditions.

     

Oxygen binding characteristics of Artemia hemoglobin domains

• 1.1. The extracellular hemoglobins of the crustacean Artemia can be split into structural and functional domains by limited proteolysis.
• 2.2. The oxygen affinity of the multi-domain fragments increases linearly with decreasing molecular weight.
• 3.3. Cooperativity is expressed only in the intact dimeric molecule and not at the subunit or multi-domain level.