Adaptative features of amazon fishes: Hemoglobins,hematology, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus (Siluriformes)

• 1.1. Hemoglobin, hematological parameters, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus, from the Amazon river, were studied in three different conditions: in their natural environment, acclimated to normoxia and acclimated hypoxia conditions.
• 2.2. Nine anodal hemoglobin fractions were detected on starch gel electrophoresis. No qualitative differences in the Hb electrophoretic patterns were detected in the three studied groups.
• 3.3. Hematocrit, hemoglobin concentration, MCV, MCHC and MCH were different among studied conditions.
• 4.4. GTP was almost absent in the blood of animals in natural conditions and acclimated to hypoxia, but was present at a concentration similar to ATP in normoxic acclimated animals.
• 5.5. There is a tendency for higher Hb-O₂ affinity for hypoxic acclimated/acclimatized animals.

     

Adenosine effect on lactate and pyruvate production in the hypoxic guineapig heart

• 1.1. It has been shown that adenosine stimulates glycolysis in some cells and this ability of adenosine was tested in the hypoxic guineapig heart.
• 2.2. Adenosine (10 μM) activated lactate production in the isolated perfused guineapig heart under conditions of normoxia but did not under hypoxia.
• 3.3. Despite this, the nucleoside favorably influenced the energy metabolism of the hypoxic heart as revealed by the better posthypoxic functional recovery (98%) compared to the control without adenosine (78%).
• 4.4. Our findings suggest a role for the glycolytic pathway in this effect of the nucleoside as long as other cardiac energy-yielding pathways are strictly aerobic.

     

Osmotically-induced volume changes in isolated cells of a pond snail

• 1.1. To assess whether the stretch-activated (SA) channels in snail cells could contribute to osmoregulation, information is needed about the behaviour of the cells under anisosmotic conditions.
• 2.2. Cells of Lymnaea stagnalis were therefore examined during acute hyposmotic stress (HOS).
• 3.3. Kidney, heart and neuronal cells (monitored photographically) swelled less than expected for strictly semipermeable cells, but exhibited no regulatory volume decrease.
• 4.4. Long-term viability of the cells was not compromised following acute hyposmotic stress.
• 5.5. Quinidine, which blocks SA channels in Lymnaea, intensified stress-induced swelling most markedly in kidney cells.
• 6.6. The data can, however, be explained without invoking recruitment of SA channels.

     

Phosphofructokinase from the anterior byssus retractor muscle of Mytilvs edulis: Modification of the enzyme in anoxia and by endogenous protein kinases

• 1.1. Anoxia exposure resulted in a stable modification of the kinetic properties of 6-phosphofructo-1-kinase (PFK) from the anterior byssus retractor muscle (ABRM) of the sea mussel Mytilus edulis L.
• 2.2. Compared to the aerobic enzyme, the anoxic form of PFK. showed a reduced affinity for both substrates, fructose-6-phosphate (F6P) and ATP, and an increased sensitivity to inhibition by phosphoenolpyruvate.
• 3.3. To analyze the involvement of protein kinases in the modification of PFK, extracts from aerobic or anoxic muscle were incubated with ATP and Mg²⁺ plus protein kinase second messengers cyclic 3',5'-adenosine monophosphate (cAMP), cyclic 3',5'-guanosine monophosphate (cGMP) or Ca²⁺ plus phorbol 12-myristate 13-acetate (PMA).
• 4.4. Both forms of the enzyme responded to the presence of cAMP with a strong increase in affinity for F6P.
• 5.5. In response to cGMP affinity of the aerobic enzyme for F6P decreased whereas that of the anoxic enzyme form was not affected (at 0.5 mM ATP) or increased (at 3 mM ATP).
• 6.6. Incubation with Ca²⁺ + PMA had only a limited effect on PFK kinetics but appeared to enhance the response to cGMP when the three compounds were given together.
• 7.7. Treatment of PFK-aerobic with alkaline phosphatase resulted in a strong decrease in enzyme activity and affinity for F6P; subsequent treatment with cAMP reversed the effect on S_0.5 F6P.
• 8.8. The data indicate that PFK activity is altered during the aerobic-anaerobic transition by a change in the phosphorylation state of the enzyme and that cAMP and cGMP act oppositely to regulate PFK activity, and thereby alter glycolytic rate, during this transition.

     

The mechanism of calcium-dependent activation of respiration of liver mitochondria from hibernating ground squirrels,Citellus undulatus

• 1.1. It is shown that Ca²⁺-dependent activation of respiration of liver mitochondria from hibernating ground squirrels is accompanied by mitochondrial swelling.
• 2.2. The swelling of mitochondria from hibernating ground squirrels, as well as the activation of mitochondrial respiration, is precluded by cyclosporin A, p-bromphenacylbromide and oligomycin. Carboxyatractiloside, on the contrary, under these conditions favors the swelling and the acceleration of respiration.
• 3.3. It was concluded that Ca²⁺-dependent activation of hibernating ground squirrel liver mitochondrial respiration resulted from the appearance of a non-specific permeability pathway and from swelling of mitochondria.

     

Ecdysone-controlled meiotic reinitiation in oocytes of Locusta migratoria involves a decrease in cAMP levels

Evidence for the involvement of cAMP in the triggering of meiotic reinitiation by ecdysone in vitellogenic oocytes of Locusta migratoria is presented:

• 1.(1) the intracellular concentration of cAMP decreases significantly (by 40%) in the oocytes at the time when meiotic reinitiation is induced;
• 2.(2) drugs which increase the concentration of cAMP antagonize the stimulatory action of ecdysone;
• 3.(3) ecdysone treatment of excised oocytes is followed by a decrease in intra-cellular cAMP;
• 4.(4) ecdysone reduces the adenylate cyclase activity when added to plasma membrane preparations in vitro.

     

Effects of ATP and cAMP on salt and sugar (responses of chemosensilla in the blowfly)

• 1.1. The addition of cAMP to stimulating solutions of NaCl, fructose (furanose sugar), sucrose, or glucose (pyranose sugars) decreases the responsiveness of labellar chemosensilla in Phormia.
• 2.2. The addition of ATP, while decreasing the responsiveness to NaCl or fructose enhances the responsiveness to glucose and sucrose.
• 3.3. The inhibiting effect of ATP on NaCl or fructose responses is suppressed by GDPßS, an inhibitor of adenylate cyclase (and thus of cAMP synthesis); moreover GDPßS further enhances the increase in response due to ATP when added to the sucrose or glucose solutions.
• 4.4. Results suggest a possible involvement of cAMP and ATP in the taste reception mechanism in the blowfly.

     

Renal response to hypoxia in carp,Cyprinus carpio: Changes in glomerular filtration rate,urine and blood properties and plasma catecholamines of carp exposed to hypoxic conditions

• 1.1. Changes in glomerular nitration rate (GFR), urine and blood properties and plasma catecholamines of carp were investigated during and following hypoxia.
• 2.2. GFR and urine flow decreased with increased urinary concentrations of bio-components, except protein, in the course of hypoxia.
• 3.3. Decreases in blood pH, and increases in haematocrit value and plasma K⁺, Ca²⁺, Mg²⁺, inorganic phosphate (P_i), ammonia, lactic acid and catecholamines (CAs) were observed as hypoxia progressed.
• 4.4. Increased GFR and urine flow, and higher values for urinary components, except protein, compared with those of the control were found in the initial post-stress stage.
• 5.5. The possible significance of increased plasma CAs in relation to changes in renal function in hypoxic carp is discussed.

     

Sublethal effects of hypoxia in the abalone (Haliotis rufescens) as measured by in vivo31P NMR spectroscopy

• 1.1. Effects of hypoxia were investigated in red abalones (Haliotis rufescens) using a flow-through exposure system and in vivo³¹P NMR spectroscopy.
• 2.2. Following seawater acclimation, abalones were exposed to air for 1 hr, then seawater for 2.5 hr to check recovery; parallel controls were performed without air exposure.
• 3.3. In foot muscle, hypoxia produced a decrease in phosphoarginine concentration and intracellular pH, an increase in inorganic monophosphate concentration, and no change in that of ATP; upon resubmergence, all effects generally recovered.
• 4.4. The changes induced by hypoxia during normal tidal changes are consistent with the blockage of mitochondrial oxidative phosphorylation.
• 5.5. Use of in vivo NMR allows measurement of the biochemical effects of natural stress factors in live, intact aquatic organisms in the laboratory.

     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Possible involvement of adenylylation in the modification of a 26 kDa protein in rat parotid acinar cells

• 1.1. Adenylylation, a posttranslational modification of proteins, was investigated in saponin-permeabilized acinar cells of the rat parotid gland.
• 2.2. When cells were incubated with [2,8-³H]ATP, several proteins, including a 26 kDa protein in the particulate fraction, were labeled.
• 3.3. Upon incubation of cells with [α-³²P]ATP in the presence of cAMP and 3-isobutyl-lmethylxanthine, ³²P-labeling of the 26 kDa protein was observed.
• 4.4. After treatment with snake venom phosphodiesterase, [³²P]AMP was released from the 26kDa protein. Such release was not observed when cells were labeled with [γ-³²P]ATP.
• 5.5. The ³²P-labeling pattern of proteins with [α-³²P]ATP was clearly different from that with [adenylate-³²P]NAD⁺.
• 6.6. The results suggest that the 26 kDa protein is one of the adenylylation substrates in rat parotid acinar cells.

     

Effects of low environmental pH and temperature on hatching and metabolic rates in embryos of Anax junius drury (Odonata: Aeshnidae) and the role of hypoxia in the hatching process

• 1.1. Studies were conducted in order to determine the combined effects of low environmental pH and temperature on embryonic survival capacity and metabolic rates in the dragonfly, Anax junius Drury. Studies were also conducted to assess the effects of hypoxia on hatching success as well as to investigate the role of hypoxia as a possible physiological triggering mechanism for hatching.
• 2.2. At water temperatures of 10–30°C, an environmental pH value of 3.0 was extremely limiting and significantly reduced hatching success.
• 3.3. Over a pH range of 3.0–5.0, a water temperature of 30°C was found to be severely limiting. Over a pH range of 6.0–7.0, hatching success was greater than 80% at test temperatures ranging from 10 to 25°C.
• 4.4. Embryos of A. junius exhibited a greater tolerance to markedly low environmental pH (3.0) than that previously reported for fish and amphibians, although survival capacity was less than 10%.
• 5.5. An environmental pH value of 3.0 has a significant detrimental effect on embryonic development. Survivorship and developmental rate increase significantly over a pH range of 4.0–5.0.
• 6.6. Oxygen consumption rates were lowest for fertilized eggs exposed to a pH of 3.0 at all test temperatures (10–30°C). Metabolic rates increased significantly at pH 4.O.
• 7.7. Embryos hatch successfully under hypoxic conditions in both aqueous and nonaqueous media. Results suggest that hypoxia acts as a triggering mechanism for hatching in this aquatic insect.

     

Some properties of ATPase activity in the intact cells of yeast Saccharomycopsis fibuligera

• 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
• 2.2. Optimal pH for the activity was approximately 7.
• 3.3. The activity was stimulated by Mg²⁺.
• 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN₃, NaVO₃, or PCMB but not inhibited by ouabain.

     

Purification and some properties of an atypical alkaline p-nitrophenylphosphate phosphatase activity from Halobacterium halobium

• 1.1. An alkaline p-nitrophenylphosphate phosphatase has been purified 440-fold from extracts of Hatobacterium halobium.
• 2.2. The enzyme has an apparent molecular weight of 24,000.
• 3.3. A K_m value for p-nitrophenylphosphate of 1.12mM has been found under optimal conditions.
• 4.4. The enzyme is selectively activated and stabilized by Mn²⁺.
• 5.5. It requires high salt concentrations for stability and maximum activity.
• 6.6. It displays an unusual restricted substrate specificity of 25 phosphate esters tested, only phosphotyrosine and casein were hydrolysed besides p-nitrophenylphosphate.

     

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.

     

Morphometry and composition of red drum otoliths: Changes associated with temperature,somatic growth rate,and age

• 1.1. Size and composition of sagittal otoliths from red drum, Sciaenops ocellatus (Sciaenidae), reared at various constant temperatures were compared with otoliths from wild-caught fish.
• 2.2. Uncoupling of otolith growth and somatic growth in laboratory-reared fish was evident in otolith length, area, volume, weight, density, and organic fraction.
• 3.3. Fish grown at low temperatures had significantly smaller and less dense otoliths having a greater organic content than fish of the same size grown at higher temperatures.
• 4.4. Changes in inorganic elements were poorly related to temperature in laboratory-reared fish.
• 5.5. The effect of temperature on otolith elemental composition was small relative to the effects of age and its associated physiological changes.

     

The digestive enzymes of the pacific brown shrimp Penaeus californiensis.: I—Properties of amylase activity in the digestive tract

• 1.1. Crude extract of the whole digestive tract from the brown shrimp (P. californiensis) was investigated for digestive amylase activity.
• 2.2. Considerable amylase activity was found at pH 6.5–8.0, with optimum pH at around 7.5.
• 3.3. Optimum temperature was found between 30–40°C, similar to amylases from other crustaceans.
• 4.4. Amylase activity was highly halotolerant, having 50% maximum activity at 3 M NaCl.
• 5.5. Maximum amylase activity was found at 0.01 M NaCl.
• 6.6. Amylase activity was partially inhibited by the divalent ions Hg²⁺, Zn²⁺, Cu²⁺ and Cr²⁺.
• 7.7. Mg²⁺ and Ca²⁺ ions seemed to enhance amylase activity.

     

Crayfish retinular cells: Influence of extracellular sodium and calcium upon receptor potential

• 1.1. In crayfish, light stimulation of the retinular cells induces a depolarizing receptor potential.
• 2.2. Experiments were designed to determine the role of Na⁺ and Ca²⁺ on receptor potential during dark And light states.
• 3.3. Depolarization depends on Na⁺ and Ca²⁺ availability to the retinular cell.
• 4.4. Repolarization velocity and response duration depend on extracellular Ca²⁺ availability.
• 5.5. Light adaptation increases receptor potential dependence on calcium and sodium ions.
• 6.6. We analyse these results with respect to other invertebrate photoreceptors.

     

Haematology of the australian eastern quoll,Dasyurus viverrinus

• 1.1. A variety of haematological parameters were determined in adult Dasyurus viverrinus.
• 2.2. Haemoglobin and red cell counts were high with a very low mean cell volume.
• 3.3. Basophils are absent but the eosinophils contain small numbers of basophilic granules which may indicate a dual role for this cell.
• 4.4. “Ring Form” leucocytes are present.
• 5.5. Three types of red cell picture could be identified, some animals showing large numbers of spherocytes, spicule cells, and inclusion bodies.
• 6.6. These cells resemble those found in some inherited human haemolytic anaemias but there was no evidence of haemolysis in the animals.
• 7.7. An alkali resistant haemoglobin component is present.