THE ABSORPTION OF OXYGEN FROM LIQUID CULTURES OF BLUE-GREEN ALGAE BY ALKALINE PYROGALLOL

SUMMARY

A mixture of pyrogallol with sodium hydroxide and sodium carbonate (2:1:1) in a separate container absorbed up to 75% of the oxygen in a bicarbonate-carbonate buffered medium with more or less no change in the pH of the medium. A system in which two test tubes were added to the culture vessel, one containing saturated sodium bicarbonate and the other pyrogallol plus sodium hydroxide gave similar results, but were not investigated further because of difficulties in handling. Optimal conditions for absorption of oxygen from 100 ml of the growth medium was 1 mMole pyrogallol +0,5 mMole sodium hydroxide + 0,5 mMole sodium carbonate. The addition of this pyrogallol to alkali ratio to cultures of two Microcystis and one Synechococcus isolate in rubber stoppered flasks gave stoichiometric increases in yield which was not due to carbonate enrichment but to a lowering of oxygen tension. The data may mean that even under relatively low light intensities (1 - 4 × 10³ ergs cm^?2 sec^?1) photooxidation occurs.     

THE ABSORPTION OF ULTRA-VIOLET RADIATION BY CRYSTALLINE PEPSIN

Determination of the absorption spectra of pure preparations of Northrop''s crystalline pepsin inactivated by irradiation with ultra-violet light shows that the total absorption in the ultra-violet region of the spectrum increases with the degree of inactivation. This increase is especially marked between 2400 and 2750 Å.u. The rate of photoinactivation is shown to be sensitive to changes in pH, increasing with lower values, and evidently bears a one-quantum relationship to the energy flux. Tests of the rate of inactivation of pepsin exposed to several different bands of the ultra-violet spectrum, in relation to the absorbed energy, indicate that the destruction spectrum of the enzyme agrees essentially with its absorption spectrum and is similar to that of urease.     

THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS : II. THE CAUSE OF POTASSIUM SELECTION AS INDICATED BY THE ABSORPTION OF RUBIDIUM AND CESIUM.

1. Frog muscles perfused with Ringer solution in which potassium chloride has been replaced by an equivalent amount of rubidium or cesium chloride take up rubidium or cesium and incorporate them into the tissue substance in such form as to be retained during a subsequent perfusion with potassium-free Ringer solution, provided the muscles contract during the first perfusion. Retention of rubidium or cesium by a resting muscle does not occur. 2. Rats on synthetic diets, adequate in all respects except that potassium was replaced by an equivalent amount of rubidium or cesium, died after a period varying from 10 to 17 days with characteristic symptoms including tetanic spasms. Muscle, heart, liver, kidney, spleen, and lung tissues were then found to contain significant amounts of rubidium or cesium. The concentration of these metals in the muscle amounted, in some cases, as shown by a spectroscopic estimation, to about half the concentration of potassium normally found in mammallian muscle. 3. The results are regarded as tending to confirm the theory that the peculiarities in the physiological effects of potassium, including the facility with which it is "selected" by living cells in preference to sodium, are related to the electronic structure of the potassium ion as compared with that of similar ions. The possible relationship of the comparative migration velocity, a function of the electronic structure, to physiological effects is suggested.