Manometric Procedure Research Articles

ETHYLENE METABOLISM IN TOMATO FRUIT: II. DETERMINATION OF TOTAL AND C14-LABELLED ETHYLENE

A method has been developed for the determination of the radioactivity from C14-labelled ethylene absorbed in aqueous mercuric perchlorate – ethylene glycol. Counting was done on a liquid sample in a gas flow counter. This procedure was designed for the analysis of C14-labelled ethylene evolved by fruit to which possible ethylene precursors had been administered. Total ethylene could be measured manometrically on the same sample. The manometric procedure permitted analysis for ethylene in quantities evolved by one or two tomatoes or other fruit.

AN EXPERIMENTAL ANALYSIS OF THE DISCONTINUOUS RESPIRATION OF THE CECROPIA SILKWORM

1. The respiration of diapausing Cecropia pupae is remarkable in that metabolic carbon dioxide is retained within the insect and released during brief periods as bursts. This finding confirms Punt's prior observations on several species of diapausing insects.2. At 25° C. in 14 pupae with an average weight of 4.7 grams, bursts of carbon dioxide occurred on the average of once every 7.3 hours and the burst volumes averaged 271 mm3/animal. The average interburst rate of carbon dioxide output was 2.7 mm3/gm. live wt./hr., i.e., about one-sixth the average rate of oxygen uptake.3. The utilization of oxygen, unlike the release of carbon dioxide, shows no discontinuities and Warburg manometric procedures reveal an apparently continuous uptake of oxygen.4. Several independent lines of experimentation confirm the manometric observations that oxygen uptake by the pupa is continuous and non-cyclic and direct attention to the surprising fact that, in the interburst period, oxygen may enter the insect at ma...

A manometric determination of nitrate reductase activity

A manometric procedure for evaluating nitrite has been devised and applied to a determination of nitrate reductase activity in a halophilic vibrio in the presence of high concentrations of salt and pigmented addenda. The NaCl requirement of the nitrate reductase of intact cells and cell-free extracts of V. costicolus has been determined and activity of the enzyme evaluated in the presence of various inhibitors.

THE USE OF PYROPHOSPHATE BUFFER FOR THE MANOMETRIC ASSAY OF XANTHINE OXIDASE

Methods for the detervination of xanthine oxidase (X0) activity include (a) study of the reduction of suitable hydrogen acceptors such as oxygen (l), methylene blue (2), and cytochrome c (3), and (b) study of the disappearence of substrate (4) or the appearance of the end-product, uric acid (5). The manometric procedure has, however, been the method of choice, but is limited in its application to the determination, of liver X0 activity owing to the high rate of oxygen consumption in the absence of substrate. In the method of Axelrod and Elvehjem (1) this endogenous respiration is largely suppressed by incubating the liver homogenate for 40 minutes prior to tipping in xanthine. However, in many experiments a large endogenous respiration is encountered which entails incubation for longer periods before linear oxidation of xanthine substrate is attained. Also, with protein-depleted animals, the method gives some anomalous results, a number of “zero” livers being found. This is attributed to the inhibitory effect of an excess of substrate on the small amount of enzyme already saturated with endogenous substrate. Removal of the endogenous substrate from the homogenate by dialysis gives positive X0 activity in these cases. It has been suggested that the respiration in the endogenous flask could be suppressed by addition of 6-pteridylaldehyde, which specifically inhibits X0, but in tissue homogenates with small X0 activity this inhibitor interferes with other enzyme systems as well (6). Dixon and Elliott (7) have reported that pyrophosphate (PP) inhibits endogenous respiration and has no effect on the reduction of methylene blue by the X0 system. In the course of our studies on the elaboration

THE EFFECTS OF LIGHT ON RESPIRATION USING ISOTOPICALLY ENRICHED OXYGEN

THIS PAPER describes respiratory measurements on illuminated plants using a recording mass spectrometer and employing isotopically enriched oxygen to permit the kinetic separation of oxygen intake from oxygen production. This method of measuring respiration, while simple in principle, is somewhat more elaborate than the usual manometric procedures but is necessary to obtain reliable information on the respiratory rate of photosynthesizing plant cells. Photosynthesis and respiration involve an exchange of the same gases, oxygen and carbon dioxide. By the usual methods of measuring these processes in photo-autotrophic organisms, only net gas exchanges are observable. To evaluate correctly the rate of photosynthesis from measurements made in the light, a correction must be applied for respiratory metabolism. Some physiologists, recognizing the ambiguity of photosynthetic measurements, attempt no such correction and deal only with rates of apparent For certain problems (viz., in ecology) this may be sufficient or even preferable. Nevertheless for the solution of other interesting and fundamental problems, reliable evaluations of true or corrected photosynthetic rates are required. For example, a specific problem of considerable interest at present is the determination of the minimal quantum requirement of photosynthesis. This determination requires that a suitable respiratory correction be applied to gas exchange measurements made in the light. The current lack of consensus among investigators of the problem is due in part to disagreement about the manner in which the respiratory correction can best be evaluated. There is an extensive literature concerning the influence of light on respiration of both photosynthetic and nonphotosynthetic organisms. Photoeffects on the respiration of non-chlorophyllous plant and animal cells are usually not observed although upon illumination certain photooxidations

Separation and determination of antimycins

Several alternative assay methods for antimycins are described. A manometric procedure based on inhibition of yeast respiration can be completed within 1–2 hr., and thus permits close control of production and purification procedures. The presence and relative amounts of several active fractions in crude antimycin fermentation broths were established by means of paper chromatography. Improvements in the procedure for isolation of antimycin A and the further purification of this antibiotic are also described.

Direct titrimetric method for determination of carbonates in small amounts of serum.

Summary1. A direct acidimetric titration method is presented for the estimation of serum carbonate in small volumes of serum or plasma. Serum bicarbonate is precipitated as the barium salt by the addition of barium hydroxide, the precipitated bicarbonate is dissolved in hot boric acid, and the Ba(H2BO3)2 in solution is titrated with standard acid to the pH of a pure solution of boric acid with the aid of an ultramicro burette. The titration represents the bicarbonate in equivalents. 2. Various critical points in the method were investigated and are discussed. The probable existence in serum of a protein bound carbonate is indicated. There is close agreement between the values obtained in this method on 0.1 ml of serum and the results obtained by the manometric procedure of Van Slyke, employing 1.0 ml of serum.The authors are indebted to the valuable assistance of Miss Penni A. Lipschitz in the preparation of the manuscript, and to Mr. Bruno Elkan and Mr. Harold Schonhorn for some of the analyses performed...

Determination of Water in Insulating Oil. Manometric Procedure

Determination of Water in Insulating Oil. Manometric Procedure

Biochemical Nitrogen Fixation Studies. I. Evidence for Limited Oxygen Supply Within the Nodule

Respiration studies were undertaken with a view to obtaining fundamental information concerning the metabolic processes of legume nodules, inasmuch as the knowledge gained should facilitate investigation of the process of nitrogen fixation. The results obtained by standard manometric procedures with detached nodules from eight species of legumes may be summarized as follows: 1. The rates of respiration of nodules maintained in various oxygen-nitrogen mixtures increased as the oxygen percentage increased. The QO2 values varied between 0.62 and 6.25 with an average of about 2.2 in air, and were about 2.4 times as great in pure oxygen, with maxima for the eight species varying between 4.3 for soybean and 8.9 for hairy vetch. 2. The respiratory quotients increased with increase in size of nodule and with decrease in concentration of oxygen. In air the values varied between 1.0 and 2.0, depending largely on the size of the nodules. In pure oxygen, excluding very large nodules, the values averaged 1.03. 3. The addition of glucose to the nutrient medium produced a mean increase in QO2 of about 12 per cent in air and 14 per cent in 100 per cent oxygen. It increased the R.Q. at the lower concentrations of oxygen but not appreciably in pure oxygen. 4. These results with detached nodules are interpreted as indicating that with most nodules maintained in air, or with large nodules at oxygen concentrations even as high as 100 per cent, the interior of the nodules is under anaerobic or partially anaerobic conditions. The evidence further indicates that under natural conditions in the soil the oxygen supply inside most nodules is also limited. 5. Crushed nodules gave higher QO2 values when maintained in air than did whole nodules, but usually lower values than whole nodules in pure oxygen. This method of increasing the aeration of the inner cells of the nodules was not very satisfactory. 6. The nodules of all the species showed rather similar responses, the variations between species being not much greater than that within species.

Biochemical Nitrogen Fixation Studies. II Comparative Respiration of Nodules and Roots, Including Non-Legume Roots

The results of respiration studies with detached nodules, legume roots, and non-legume roots from several species of plants, carried out according to standard manometric procedures, are as follows: 1. Rates of respiration of legume nodules and small legume and non-legume roots maintained in a nutrient solution in air averaged nearly the same, the QO2 values being about 2.2. Rates of respiration of the roots of various species of plants showed no marked differences for roots of comparable age, size, and condition. 2. Respiratory quotients of small legume and non-legume roots maintained in air were usually slightly less than 1.0 and hence were definitely lower than for nodules, although large roots may also show values considerably above 1.0 because of slow oxygen penetration. 3. Rates of respiration per unit of dry matter of legume nodules in pure oxygen were more than twice as great as in air, whereas values for the small legume and non-legume roots were usually not markedly affected by the additional oxy...