scholarly journals The hydrogen-ion concentration and the oxidation-reduction potential of the cell-interior: a micro-injection study

1925 ◽  
Vol 98 (689) ◽  
pp. 259-286 ◽  
Keyword(s):  
Methylene Blue ◽  
Gentian Violet ◽  
Reducing Power ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Living Organisms ◽  
Actual Formation ◽  
Qualitative Estimation

It has been recognised since the middle of the eighteenth century that one of the most fundamental characteristics of living organisms is their capacity to oxidise substances incapable of oxidation at ordinary temperatures; but no qualitative estimation of this power of oxidation was carried out until the time of Ehrlich, whose classical experiments on the injection of methylene blue into the intact animal revealed the fact that certain organs seemed to have a higher reducing power than others. Later, much histo-chemical work was done. Numerous observers studied the effect of staining tissues and cells in reagents which indicated by their colour whether they were reduced or oxidised. Several such indicators were used by the earlier workers, especially alphanaphthol and pyronin and alpha-naphthol and gentian violet; but the two chief methods were the intracellular formation of an indophenol, introduced by Röhmann and Spitzer in 1895 (20), and the oxidation of the leucobase of methylene blue, introduced by Unna in 1911 (23). In the latter case the cell was placed in a solution of the completely reduced dye, and the conclusion was that wherever the blue colour appeared, there the cell had been able to oxidise it. The indophenol method depended on the actual formation and precipitation of a dye in the cell by an oxidative condensation. The original reactants used were dimethylparaphenylenediamine and alpha-naphthol, but various later workers modified this by using other phenols and other aromatic amines, so that indophenols of different colours were produced.

scholarly journals A study of an insect cuticle: the formation of the puparium of Sarcophaga falculata Pand. (Diptera)

1947 ◽  
Vol 134 (874) ◽  
pp. 79-110 ◽  
Keyword(s):  
Methylene Blue ◽  
Reduction Potential ◽  
Reducing Power ◽  
Tyrosinase Activity ◽  
Enzymatic Oxidation ◽  
Insect Cuticle ◽  
Potentiometric Studies ◽  
Mature Larva ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

The structural and chemical changes taking place in the cuticle of the mature larva of Sarcophaga as it is converted into the puparium are fully described. The formation of the hard and dark exocuticle of the puparium from the outer endocuticle of the larva is due, as Pryor (1940 b ) has shown, to the action of a phenol derived from the blood, a polyphenol oxidase located in the inner epicuticle and present considerably before pupation being responsible for the rapid oxidation of the phenol. The blood phenol, although spontaneously oxidizable, passes unchanged through the inner endocuticle which remains soft and white, and this may be correlated with the ability of the inner endocuticle to reduce methylene blue. The phenol hardening the puparium is produced in the blood by the enzymatic oxidation of tyrosine. Tyrosine in the blood increases steadily in amount before pupation, and during this period the enzyme tyrosinase also appears and increases. The source of tyrosinase appears to lie in the oenocytoids of the blood, which increase in number as the larva matures and die away shortly before pupation. But although tyrosine and tyrosinase are present together in the blood of the mature larva, inhibiting conditions prevent the activity of the enzyme until very shortly before pupation. Tyrosinase activity, however, may be experimentally stimulated before pupation by the action of methyl alcohol and more slowly by narcotics, and it is speculated that the inhibition of tyrosinase in the mature larva may perhaps be effected by the activity of a further enzyme, a dehydrogenase, which operates by increasing the reducing power of the blood. Colorimetric and potentiometric studies of the reducing power of the blood have been carried out, and it has been found that the oxidation-reduction potential of the blood decreases steadily as the larva matures, and then rises sharply just before pupation. The coincidence of this rise with the period of liberation of the pupation hormone suggests that one function of the hormone is to destroy the reducing power of the blood, so liberating tyrosinase activity and leading to the production of a polyphenol which passes into and hardens the cuticle. In conclusion, it is suggested that the homology between the insect and crustacean cuticles is closer than has been hitherto emphasized.

scholarly journals Further micro-injection studies on the oxidation-reduction potential of the cell-interior

1926 ◽  
Vol 99 (698) ◽  
pp. 383-397 ◽  
Keyword(s):  
Reduction Potential ◽  
Chemical Properties ◽  
Ion Concentration ◽  
Egg Cell ◽  
Cell Interior ◽  
Hydrogen Ion Concentration ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Physico Chemical ◽  
Before And After

In previous communications on this subject (20, 21, 22) we described the results obtained when coloured indicators of known physico-chemical properties were injected into individual living cells. Using a modification of the micromanipulator of Chambers (4), we have worked with various unicellular protozoa and egg-cells, and have been able to draw definite conclusions as to the average hydrogen-ion concentration and the average oxidation-reduction potential of the cell interior. Our first communication dealt with the amœba, and we showed that its internal p H was probably in the neighbourhood of 7.6, while its internal r H (oxidation-reduction potential, 5) was between 17 and 19. Both values are near neutrality, so that this cell could be said to be slightly alkaline and slightly on the electronegative or reducing side of oxidation-reduction neutrality. We next extended our investigation to several types of marine egg-cells before and after fertilisation, and during the early cleavage stages. The changes which the internal p H and r H undergo during these ontogenetic events are very small indeed, and the phylogenetic differences, for example, as between the ovum of the polychsete worm and that of the starfish are correspondingly slight. The egg-cell, then, appeared to have a of about 6.6 and an r H of the order of 21 or 22. It was therefore a little on the acid side of acidbase neutrality and a little on the electropositive side of oxidation-reduction neutrality, differing on both these counts from the amœba. The amœba, therefore, has a higher intensity of reduction than the egg-cell.

scholarly journals The hydrogen-ion concentration and oxidation-reduction potential of the cell-interior before and after fertilisation and cleavage: A micro-injection study on marine eggs

1926 ◽  
Vol 99 (695) ◽  
pp. 173-199 ◽  
Keyword(s):  
Single Cells ◽  
Biological Data ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Reduction Potentials ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Egg Membrane ◽  
The Moment

In our previous communications on this subject we have described experiments dealing with the micro-injection of indicators into single cells. In the conclusion to our paper (10 a ) on the p H. and r H of the Amœba, we said, “It is hoped that other biological data will soon be available . . . such problems as the . . . oxidation-reduction potentials of egg-cells before and after fertilisation at once present themselves.” The present paper is devoted to these problems. Warburg (17) and Meyerhof (8), and afterwards other workers, observed an enormous increase in the oxygen-consumption of the egg to take place on fertilisation. Shearer (12) found that this occurred at the moment of contact of the spermatozoon with the egg membrane. In view of the fact that the increase was about 2000 per cent., it was clearly a matter of great interest to determine whether the r H changed at the same time. We have attempted to follow the changes in r H by micro-injection experiments and by staining. The two methods failed to give concordant results for reasons which are discussed in the text.

scholarly journals Physiological Studies on Thrips in Relation to Transmission of Tomato Spotted Wilt Virus

1954 ◽  
Vol 7 (3) ◽  
pp. 274 ◽  
Author(s):  
MF Day ◽  
H Irzykiewicz
Keyword(s):  
Tomato Spotted Wilt Virus ◽  
Reduction Potential ◽  
Thrips Tabaci ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Tomato Spotted Wilt ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Wilt Virus

The hydrogen ion concentration of the midguts of larval and adult Thrips tabaci and T. imaginis is between pH 5�0 and 5�6. The oxidation-reduction potential at these values is between + 0�184 and + 0�262 V. There is thus no difference between thrips that are vectors and those that are not vectors of the virus causing tomato spotted wilt. Furthermore, the pH and Eh conditions in the midgut of larval T. tabaci are unsuitable for long survival of the virus.

The Physiology of Hatching of Eggs of Ascaridia galli

1961 ◽  
Vol 35 (S1) ◽  
pp. 151-156 ◽  
Author(s):  
W. P. Rogers
Keyword(s):  
Reduction Potential ◽  
Carbonic Acid ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Ascaridia Galli ◽  
Hydrogen Ion Concentration ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Gaseous Carbon Dioxide

The stimulus for the hatching of infective eggs of Ascaridia galli in vitro depended upon the concentration of undissociated carbonic acid plus dissolved gaseous carbon dioxide, the oxidation-reduction potential, and the hydrogen ion concentration. There was considerable overlap in the conditions which favoured the hatching of eggs of Ascaridia galli and Ascaris lumbricoides; both would be expected to hatch in the small intestine of a suitable species of host.

scholarly journals Resistance-Trained Individuals Are Less Susceptible to Oxidative Damage after Eccentric Exercise

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Ypatios Spanidis ◽  
Dimitrios Stagos ◽  
Christina Papanikolaou ◽  
Konstantina Karatza ◽  
Andria Theodosi ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Eccentric Exercise ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Protein Carbonyls ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Exercise Induced ◽  
Training Background

It has been proposed that exercise-induced oxidative stress and adaptations are dependent on training status. In this study, we examined the effects of training background on free radical generation and adaptations after eccentric exercise. Forty volunteers were divided into two groups (trained and untrained) and were asked to perform eccentric exercise. Then, their blood samples were collected pre, 24, 48, and 72 hours postexercise. Biomarkers indicating oxidative damage and the antioxidant profiles of the participants were measured in plasma and erythrocyte lysate both spectrophotometrically and chromatographically. The results revealed that the untrained group depicted more severe oxidative damage (protein carbonyls, malondialdehyde), weaker antioxidant status (reduced glutathione, static and capacity oxidation-reduction potential), and weaker radical-scavenging activity (superoxide radical scavenging and reducing power) compared to the trained participants. Our findings show that trained individuals are less susceptible to oxidative damage and suggest that generalized nutritional recommendations regarding recovery after exercise should be avoided.

scholarly journals PROTEOLYTIC ENZYMES

1946 ◽  
Vol 29 (4) ◽  
pp. 219-247 ◽  
Author(s):  
David Grob
Keyword(s):  
Proteolytic Enzymes ◽  
Reducing Agents ◽  
Sulfhydryl Groups ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Oxidizing Agents ◽  
Neutral Ph ◽  
Oxidation Reduction ◽  
Antiproteolytic Activity ◽  
Sulfhydryl Compounds

1. The literature on conditions affecting the activity of proteolytic enzymes has been reviewed. 2. Experimental data on the control of the activity of trypsin, leucoprotease, papain, serum antiprotease, leucopeptidase, and pancreatic peptidase have been presented. These data indicate that: (a) The polymorphonuclearleucocytes of the cat contain abundant proteinase and peptidase active at neutral pH; those of the rabbit lack proteinase active at neutral pH. (b) Reducing agents, including several biologically important thiol-sulfhydryl compounds and ascorbic acid, inhibit the activity of leucoprotease and trypsin. For each reductant the degree of inhibition is proportional to the reducing capacity of the medium. (c) p-Aminobenzoic acid, sulfonamides (especially sulfathiazole), and many diphenyl sulfones inhibit the activity of leucoprotease. (d) Serum, plasma, several heavy metals, ammonium salts, asparagine, thiourea, heparin, glutamic acid, tyrothricin, calcium chloride, and bile salts and bile acids also inhibit the activity of leucoprotease, and in most cases of trypsin too. (e) Preparations of tryptic digests of proteins, and egg white trypsin inhibitor, inhibit trypsin to a much greater degree than leucoprotease. (f) Mild oxidizing agents increase the activity of leucoprotease and trypsin. (g) Oxidizing agents and some inhibitors of sulfhydryl groups inhibit the antiproteolytic activity of the serum. It is suggested that serum antiprotease may consist (chiefly) of reducing agents, including thiol-sulfhydryl peptides which exert their antiproteolytic activity by virtue of the presence of sulfhydryl groups. (h) The antiproteolytic activity of the serum is progressively weakened by exposure to a hydrogen ion concentration below pH 6.5 or above pH 9.7. Because of this the pH optima of leucoprotease and trypsin are shifted in the presence of serum from pH of 7 and 8 to pH of 6 to 6.5, and the range of activity of these enzymes is slightly widened, in both acid and alkaline reactions. (i) Reducing agents increase the activity of leucopeptidase and pancreatic peptidase. Serum, sulfathiazole, and thiourea have little or no effect. 3. The significance of the oxidation-reduction system in the control of the activity of leucoprotease, trypsin, serum antiprotease, leucopeptidase, and pancreatic peptidase has been emphasized.

Inhibitors of Tyrosinase

1955 ◽  
Vol 32 (3) ◽  
pp. 468-484
Author(s):  
M. G. M. PRYOR
Keyword(s):  
Methylene Blue ◽  
Dissolved Oxygen ◽  
Inhibitory Effect ◽  
Tyrosinase Activity ◽  
Aromatic Substrate ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Low Concentrations ◽  
Sulphydryl Groups

1. It has been reported that if Drosophila larvae are ground to a fine paste with sand, the homogenate shows little tyrosinase activity, but that if the larvae are allowed to blacken in chloroform vapour before grinding, activity is increased. 2. This has been interpreted as showing the effect of an intracellular inhibitor, set free by rupturing the cells, but destroyed by chloroform. This inhibitor has been identified by previous authors as a dehydrogenase. 3. It is here suggested that the lack of activity of Drosophila extracts prepared with sand is due to destruction of tyrosinase as it oxidizes naturally occurring aromatic substrates. 4. It is shown that tyrosinase is destroyed by oxidizing the aromatic substrate present in the cuticle of Calliphora larvae, or by very low concentrations of homocatechol. 5. The aromatic substrate of Calliphora larvae is concentrated in the cuticle, and would be set free by fine grinding. 6. Drosophila or Calliphora larvae yield a more active extract when ground with sand than when simply crushed, provided that they are tested soon after grinding. 7. The tyrosinase activity of such extracts is not increased by chloroform or methanol. 8. The compound between o-quinones and amino-acids is capable of oxidizing ascorbic acid or excess amino-acid without the aid of an enzyme, and of simultaneously reducing methylene blue. 9. This reaction, rather than the activity of dehydrogenases, is probably responsible for most of the ability of damaged insect tissue to bleach methylene blue. 10. The blood of insects normally contains dissolved oxygen in equilibrium with the air. 11. The reaction involved in the blackening of insect blood may consume all the dissolved oxygen. 12. Previous observations on fluctuations in the oxidation-reduction potential of the blood of Calliphora larvae with age are probably due to changes in the rate at which oxygen is consumed by the blood after it is shed. 13. There does not therefore appear to be any valid evidence that tyrosinase is inhibited in vivo by the action of dehydrogenases. The absence of tyrosinase activity in undamaged tissue is probably due to the structure of the cytoplasm, which keeps enzyme and substrate apart. 14. Instances of the inhibition of tyrosinase reported in Crustacea and Echinodermata seem to be susceptible of the same explanation as in insects. 15. The supposed inhibitory effect of sulphydryl groups reported for vertebrate melanophores is shown to be due to the combination of sulphydryl groups with o-quinones, which prevents the formation of melanins.

scholarly journals A STABLE HEMOLYSIN-LEUCOCIDIN AND ITS CRYSTAL-LINE DERIVATIVE ISOLATED FROM BETA HEMOLYTIC STREPTOCOCCI

1938 ◽  
Vol 67 (4) ◽  
pp. 643-657 ◽  
Author(s):  
E. J. Czarnetzky ◽  
Isabel M. Morgan ◽  
Stuart Mudd
Keyword(s):  
Molecular Weight ◽  
Methylene Blue ◽  
Sodium Salt ◽  
Blood Cells ◽  
Chemical Structure ◽  
Free Acid ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
High Degree

1. A chemically pure hemolysin-leucocidin has been isolated from ß hemolytic streptococci, but not from other species of bacteria studied. 2. It does not give rise to antibodies, but precipitates immune sera against hemolytic streptococci, and is therefore a hapten. 3. A highly purified sample of S. H. up to a dilution of 1:128,000 hemolyzes red blood cells. Its hemolytic activity is not specifically neutralized by antiserum versus ß hemolytic streptococci. It is leucocidic in that it inhibits the reduction of methylene blue by leucocytes. 4. The hemolysin-leucocidin is stable to oxygen, to heat and to moderate changes in hydrogen ion concentration. Its chemical structure has been determined in part. Its molecular weight is 2260. 5. A crystalline derivative has been isolated as the sodium salt from the hemolysin-leucocidin. As the free acid it has a molecular weight of 720. Its hemolytic and leucocidic activity parallels that of S. H., although it is not serologically active. It possesses a high degree of toxicity for mice and rabbits.

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