Effect of Ultracentrifuging on Oxygen Consumption of the Eggs of Ascaris suum,Goeze

Abstract

That the maintenance of structural integrity is of prime importance for the normal functioning of a large part of the oxidative processes of the cell has been demonstrated by a number of workers.1-5 Bodine and Boell 6 , 7 have shown that the normal activity of much of the so-called cyanide sensitive respiratory mechanism (indophenol oxidase system) is interfered with as the result of the structural disorganization of the cell. Recently Beams and King 8 found that cleavage in the eggs of Ascaris suum was not affected even though the eggs were subjected to forces of 150,000 to 400,000 times gravity (obtained through the use of the Beams 9 ultracentrifuge). Although such eggs were completely stratified into a centrifugal cap of heavy yolk material, a middle band of clear protoplasm, and a light layer of lipoidal material, cleavage rate in centrifuged eggs was not noticeably different from that in normal eggs.

The purpose of the experiments reported herein was to determine the effect of ultracentrifuging on the oxygen consumption of the eggs of Ascaris suum.

The eggs used were obtained fresh from adult worms, expressed into saline, washed repeatedly to remove surplus albumin, and stored at 5°C. until needed. In the centrifuge experiments a concentrated suspension of eggs was rotated for 30 minutes at a force of 150,000 times gravity. Oxygen consumption was measured by means of sensitive microdifferential manometers (Ko₂ = 0.160). In an experiment one drop of a concentrated suspension of ova (containing ca. 5,000 eggs) was supported by a convenient hanger in the manometer vessel. Ten percent KOH was used to absorb CO₂. In the experiments involving the use of cyanide a freshly prepared KCN solution was neutralized with HCl to pH 7.0 and diluted to 0.001 molar immediately before use. Eggs were washed 3 times with cyanide and were then supported in the manometer in cyanide. KOH-KCN mixtures for absorbing CO₂, as recommended by Krebs 10 and van Heyningen, 11 were used. For each sample of eggs tested, the respiratory rate of normal eggs was determined in duplicate; the effect of centrifuging or cyanide, in duplicate or triplicate. O₂ uptake was measured at 30° ± 0.02°C. over a 4 to 6-hour interval. At the end of the experimental period the eggs were flooded over a squared slide and counted. The respiratory rate (Qo₂) was calculated in terms of mm. 3 O₂ per hour per 10 6 eggs.