The Kinetics of Peripheral Exchanges of Water and Electrolytes in the Silver Eel (Anguilla Anguilla L.) in Fresh Water and in Sea Water

1972 ◽  
Vol 57 (2) ◽  
pp. 489-512
Author(s):  
R. KIRSCH
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Anguilla Anguilla ◽  
Osmotic Gradient ◽  
Silver Eel ◽  
Experimental Tank ◽  
Experimental Conditions ◽  
Control Measurement ◽  
Internal Medium ◽  
Kinetics Of

1. New experimental techniques are described for the investigation of water and electrolyte fluxes in the eel by studying the internal medium, the urine and the external medium. An experimental tank made up of two compartments isolates the water containing the head from the water containing the trunk and tail of the animal. The two water circuits are separated by remote control. Measurement can thus be made without handling the eel previously adapted to experimental conditions. 2. The freshwater eel shows low branchial exchanges and low chloride urinary losses. A positive correlation between urinary excretion of water and sodium has been shown. 3. The silver eel's skin is impermeable to water and chlorides. 4. The eel reacts to FW-SW transfer by immediately drinking water. The drinking reflex is therefore not triggered by dehydration due to the osmotic gradient. 5. During SW adaptation the eel presents a transitory hyperactivity phase of the branchial outflux corresponding to plasma hypermineralization. 6. The eel which has been adapted to sea water for 3 weeks shows the lowest chloride exchanges ever recorded among marine teleosts.

The effect of external salinity on drinking rate and rectal secretion in the larvae of the saline-water mosquito Aedes taeniorhynchus

1977 ◽  
Vol 66 (1) ◽  
pp. 97-110
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Narrow Range ◽  
Saline Water ◽  
Fluid Secretion ◽  
Osmotic Concentration ◽  
Drinking Rate ◽  
Aedes Taeniorhynchus ◽  
External Salinity ◽  
Kinetics Of

1. The drinking rate of the saline-water mosquito larva Aedes taeniorhyncus (100 nl.mg-1.h-1) is unaffected by the salinity of the external medium, but is directly proportional to the surface area of the animal. 2. Haemolymph Na+, Mg2+, K+, Cl-, SO42- and osmotic concentrations were measured in larvae adapted to 10%, 100% and 200% seawater and were found to be regulated within a narrow range. 3. With the exception of potassium, ionic concentrations in rectal secretion were found to increase with increasing concentrations of the sea water in which larvae were reared. 4. The osmotic concentration of rectal secretion was unaffected by changes in haemolymph osmotic concentration but did rise when sodium or chloride concentrations of the haemolymph were increased. High levels of these ions also stimulated the rate of fluid secretion. 5. Transport of chloride and sodium by the rectum exhibits the kinetics of allosteric rather than classical enzymes.

Kinetics of Water and Chloride Exchanges During Adaptation of the European Eel to Sea Water

1973 ◽  
Vol 58 (1) ◽  
pp. 105-121
Author(s):  
R. KIRSCH ◽  
N. MAYER-GOSTAN
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Maximum Level ◽  
Progressive Increase ◽  
Plasma Sodium ◽  
European Eel ◽  
Drinking Rate ◽  
The One ◽  
Kinetics Of

Using isotopic procedures, the drinking rate and chloride exchanges were studied in the eel Anguilla anguilla during transfer from fresh water to sea water. 1. Following transfer to sea water there is a threefold increase of the drinking rate (lasting about 1 h). Then it falls to a minimum after 12-16 h and rises again to a maximum level about the seventh day after the transfer. Then a gradual reduction leads to a steady value which is not significantly different from the one observed in fresh water. 2. The changes with time of the plasma sodium and chloride concentrations are given. Their kinetics are not completely alike. 3. The chloride outflux increases 40-fold on transfer of the eel to sea water, but even so it is very low. After the sixth hour in sea water there is a progressive increase in the flux, so that on the fourth day it is higher (500 µ-equiv. h-1.100 g-1) than in the seawater-adapted animals (230 µ-equiv.h-1.100 g-1). 4. Drinking rate values in adapted animals are discussed in relation to the external medium. The kinetics of the drinking rate together with variations in body weights after freshwater-seawater transfer are discussed in relation to the possible stimulus of the drinking reflex. 5. Chloride fluxes (outflux, net flux, digestive entry) are compared and lead one to assume that in seawater-adapted fish one-third of the chloride influx enters via the gut and two-thirds via the gills.

Temperature-Dependence of Permeability to Water and to Sodium of the Gill Epithelium of the Eel Anguilla Anguilla

1972 ◽  
Vol 56 (3) ◽  
pp. 587-600 ◽  
Author(s):  
R. MOTAIS ◽  
J. ISAIA
Keyword(s):  
Temperature Dependence ◽  
Water Permeability ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Temperature Acclimation ◽  
Osmotic Gradient ◽  
Surprising Result ◽  
Sodium Permeability ◽  
Osmotic Permeability ◽  
Diffusional Permeability

1. The temperature dependence of diffusional permeability to water was studied in freshwater-adapted and seawater-adapted eels. The pattern of temperature acclimation is discussed. 2. The ratio of water permeability to sodium permeability is approximately 3 at 25°C, but falls to 1 at 5°C. This drop is mainly due to a diminution of the water permeability, the temperature coefficients being much higher for water than for sodium. 3. The relatively independent variations of water and sodium permeabilities in the seawater-adapted fish probably indicate a certain dissociation between water movements and salt movements. 4. In the freshwater-adapted eel the osmotic permeability is considerably higher than the diffusional permeability, which supports the previously advanced hypothesis concerning the presence of water-filled channels in the branchial epithelium. 5. In the seawater-adapted eel the osmotic permeability is lower than the diffusional permeability, this difference being greater the lower the temperature. This surprising result must signify either that the osmotic pressure difference between blood and sea water does not represent the true osmotic gradient across the membrane, or that a reabsorption of water linked with a movement of solutes occurs in a specialized region of the gill.

STUDIES ON THE EXPERIMENTAL ALTERATION OF WATER AND ELECTROLYTE COMPOSITION OF THE EEL (ANGUILLA ANGUILLA L.)

1967 ◽  
Vol 37 (3) ◽  
pp. 297-317 ◽  
Author(s):  
D. K. O. CHAN ◽  
I. CHESTER JONES ◽  
I. W. HENDERSON ◽  
J. C. RANKIN
Keyword(s):  
Body Weight ◽  
Serum Potassium ◽  
Sea Water ◽  
Extracellular Fluid ◽  
Anguilla Anguilla ◽  
Electrolyte Composition ◽  
Normal Range ◽  
Experimental Conditions ◽  
Corpuscles Of Stannius ◽  
Freshwater Eel

SUMMARY The distribution of water, electrolyte composition (Na, K, Ca, Mg, PO4, Cl) and extracellular fluid volume of eels (Anguilla anguilla L.) were investigated under different experimental conditions. Adrenalectomy of the freshwater eel was followed by an increase in body weight, a fall in the amount and concentration of sodium in serum and muscle and a shift of water into the cells. The concentration of serum potassium remained within the normal range. Adrenalectomy of the sea-water eel was followed by a decrease in body weight and an increase in the concentration of extra- and intracellular sodium. The concentration of serum calcium also increased, that of potassium remained within the normal range but the actual content diminished. Removal of the corpuscles of Stannius from the freshwater eel gave some effects similar to adrenalectomy. There was, however, no significant increase in body weight but the concentrations of serum potassium and calcium rose. Removal of the corpuscles from the sea-water eel brought about changes similar to, but less pronounced than those after adrenalectomy. The results of the injection of mammalian corticotrophin, cortisol, aldosterone and anti-aldosterone compounds are given. They are discussed in the light of the possible roles of the adrenal cortex and the corpuscles of Stannius in the maintenance of homeostasis of the eel in different environments.

scholarly journals Pools and protein synthesis in mammalian cells

1979 ◽  
Vol 178 (3) ◽  
pp. 699-709 ◽  
Author(s):  
J H Robertson ◽  
D N Wheatley
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Mammalian Cells ◽  
External Medium ◽  
Essential Amino Acids ◽  
Poor Correlation ◽  
Experimental Conditions ◽  
Linear Kinetics ◽  
Kinetics Of

From the kinetics of incorporation into protein shown by four amino acids and one amino acid analogue in suspension cultured HeLa S-3 cells, two distinctly different patterns were observed under the same experimental conditions. An initial slow exponential incorporation followed by linear kinetics was characteristic of the two non-essential amino acids, glycine and proline, whereas the two essential amino acids studied, phenylalanine and leucine, showed linear kinetics of incorporation with no detectable delay. The analogue amino acid, p-fluorophenylalanine also showed immediate linear kinetics of incorporation. There was a poor correlation between the rate of formation of acid-soluble pools and incorporation kinetics. However, the rate of formation of the freely diffusible pool of amino acids correlated more closely with incorporation kinetics. The lack of direct involvement of the acid-soluble pool in protein synthesis was also demonstrated by pre-loading of pools before treatment of cells with labelled amino acids. The results partially support the hypothesis that precursor amino acids for protein synthesis come from the external medium rather than the acid-soluble pool, but suggest that the amino acid which freely diffuses into the cell from the external medium could also be the source.

Plasma concentrations of ovarian steroids in the freshwater European silver eel (Anguilla anguilla L.): effects of hypophysectomy and transfer to sea water

1987 ◽  
Vol 114 (2) ◽  
pp. 289-294 ◽  
Author(s):  
B. Quérat ◽  
K. Nahoul ◽  
A. Hardy ◽  
Y. A. Fontaine ◽  
J. Leloup-Hâtey
Keyword(s):  
Plasma Levels ◽  
Sea Water ◽  
Plasma Concentrations ◽  
Anguilla Anguilla ◽  
Aromatase Activity ◽  
Silver Eel ◽  
Ovarian Steroids ◽  
Silver Eels ◽  
Dependent Inhibition ◽  
Stimulation Of

ABSTRACT Intact and hypophysectomized freshwater (FW) silver eels were transferred to tanks of FW or artificial sea water (SW; salinity = 0·60 osmol/l) which were simultaneously renewed twice a week. Fish were killed 2 months after transfer and plasma was assayed for ovarian steroids. In all fish, 5α-androstane-3β,17β-diol was present, while 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol were undetectable. In intact FW eels, plasma levels of testosterone, 5α-androstane-3β,17β-diol and oestradiol-17β were approximately 0·15 nmol/l. In intact SW eels, no change in plasma levels of testosterone and 5α-androstane-3β,17β-diol was found, whereas the concentration of oestradiol-17β was increased significantly (P<0·01), indicating stimulation of aromatase activity. In hypophysectomized compared with intact FW fish, plasma levels of testosterone and 5α-androstane-3β,17β-diol were decreased (P<0·05) and there was a slight but significant (P<0·01) augmentation of the plasma concentration of oestradiol-17β which may have involved the removal of pituitary-dependent inhibition of aromatase activity, possibly by 5α-reduced compounds. In hypophysectomized compared with intact SW fish, plasma levels of testosterone, 5α-androstane-3β,17β-diol and oestradiol-17β were decreased (P<0·05); in the case of oestradiol-17β, this may have reflected the diminished ovarian synthesis of testosterone, its precursor. The plasma level of oestradiol-17β was, however, higher in SW than in FW fish, even in hypophysectomized eels. This suggests that extra-pituitary mechanisms mediate, at least partly, the effects of transfer to SW on aromatase activity. J. Endocr. (1987) 114, 289–294

scholarly journals Kinetics of Non-Enzymatic Synthesis of Dipeptide Cbz-Phe-Leu with AOT Reversed Micelles

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1003
Author(s):  
Michiaki Matsumoto ◽  
Tadashi Hano
Keyword(s):  
Enzymatic Synthesis ◽  
Maximum Yield ◽  
Side Reactions ◽  
Experimental Conditions ◽  
Operational Conditions ◽  
Ph Dependency ◽  
Optimum Water Content ◽  
Short Time ◽  
Kinetics Of ◽  
Aot Reversed Micelles

The non-enzymatic synthesis of N-benzyloxycarbonyl-L-phenylalanyl-L-leucine (Cbz-Phe-Leu) from lipophilic N-benzyloxycarbonyl-L-phenylalanine (Cbz-Phe) and hydrophilic L-leucine (Leu), by N, N’-dicyclohexylcarbodiimide (DCC) as a condensing agent, was carried out using a reversed micellar system composed of bis(2-ethylhexyl) sodium sulfosuccinate (AOT) as a surfactant and isooctane. We successfully synthesized Cbz-Phe-Leu in a short time and investigated the effects of its operational conditions, the DCC concentration, w0, and the pH on the kinetic parameters and the maximum yields. For dipeptide synthesis, we had to add an excess of DCC with the substrates because of the side reactions of Cbz-Phe. From the pH dependency of the reactivity, a partially cationic form of Leu was better for a synthesis reaction because of the enrichment of Leu at the interface by anionic AOT. The optimum water content on the dipeptide synthesis was w0 = 28 due to the competition of the peptide synthesis and the side reactions. The maximum yield of Cbz-Phe-Leu was 0.565 at 80 h under optimum experimental conditions.

Copolymerization of Isobutene and Isoprene at “High” Temperature with Syncatalyst Systems Based on Aluminum Organic Compounds

1976 ◽  
Vol 49 (4) ◽  
pp. 937-959 ◽  
Author(s):  
S. Cesca ◽  
M. Bruzzone ◽  
A. Priola ◽  
G. Ferraris ◽  
P. Giusti
Keyword(s):  
Energy Savings ◽  
Ion Pairs ◽  
Great Part ◽  
Methyl Chloride ◽  
Reactivity Ratio ◽  
Experimental Conditions ◽  
Noticeable Increase ◽  
Catalyst Systems ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract New catalyst systems based on alkylaluminum derivatives and halogen or interhalogen compounds were found highly efficient in the synthesis of high-molecular-weight IIR at temperatures above − 50°C. The reaction mechanism was studied in detail for the system Et2AlCl + Cl2. The reactions occurring between chlorine, isobutene, Et2AlCl, and the solvent (CH3Cl) were elucidated and studied under various experimental conditions (e.g. presence or absence of light, simultaneous presence of the copolymerization system components, temperature, type of halogen, use of model compound of isobutene). It was concluded that halogenium ions, i.e. Cl+, Br+, or I+, are the initiating species. Kinetic and conductometric investigations showed that scarcely dissociated ion pairs, e.g. Cl+[Et2AlCl2]−, were formed in the absence of monomer; but in the presence of isobutene, a noticeable increase of the electrical conductivity and rapid polymerization occurred. The maximum polymerization rate was first order with respect to the concentrations of monomer, Cl2, and Et2AlCl. In the homopolymerization of isobutene, transfer to monomer and termination reactions were negligible. The MW of IIR was found to be mainly dependent on the concentrations of the catalyst components, on isoprene concentration, and on temperature. The reactivity ratio of isobutene with isoprene was found to be r1=2.5±0.5 at −35°C, while the activation energies relative to MW were −5.8 ± 0.4, kcal/mol for polyisobutene, and −5.7 ± 0.7 and − 4.3 ± 0.5 kcal/mol for IIR containing, respectively, 1.3 and 1.9 mol% of isoprene. The evaluation of some physicochemical and technological properties of typical IIR produced with the system Et2AlCl + Cl2, indicated that isoprene is randomly distributed along the chains and that the MWD is monomodal, while the glass transition temperature, tensile properties, mechanical-dynamic spectra, and kinetics of vulcanization are very similar to those of commercial IIR. Very preliminary data, referring to several classes of new catalyst systems yielding IIR having good properties, were also obtained. The syncatalyst systems here described can work in a homogeneous phase consisting of an aliphatic hydrocarbon besides methyl chloride, still giving IIR with high MW. Therefore, a completely homogeneous process can be envisioned for the synthesis of IIR at −50°C thus avoiding a great part of the fouling problems of the slurry process. The economic advantage of using “high” temperatures of polymerization is briefly discussed in terms of energy savings.

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