The Pyruvate Metabolism of Sea Urchin Eggs During the Process of Cell Division

Abstract

Since the classical discovery of Warburg (1) that fertilization of sea urchin eggs produces a sudden increase in the oxygen uptake, numerous investigators have attempted to correlate this increase to chemical changes. Perlzweig and Barron (2) found that the eggs of Arbacia punctulata contain carbohydrates and produce lactic acid. However, no increase in lactic acid formation was detected on fertilization. In 1933, RunnstrSm (3) found that 'during fertilization there is an increase in the formation of acid, the nature of which is still unknown. In 1935, ~3rstrtim (4) reported an increase in ammonia formation, which he attributed to the degradation of purines (5). This ammonia formfftion, in the opinion of Hutchens et al. (6) may be due to protein oxidation; i.e., oxidative deamination. An increased utilization of glycogen was demonstrated by 0rstrSm and Lindberg (7) and by Lindberg (8). A change in the solubility in ether and alcohol of lecithin and cephalin has also been noted: before fertilization all the cephalin is soluble in ether while after fertilization it becomes insoluble (9). Fertilization and membrane formation are essentially anaerobic processes since they can be obtained in the absence of oxygen while nuclear changes and cell division are essentially aerobic processes since they do not occur in the absence of oxygen (10). After fertilization there are an increased permeability of the cell membrane, and a channeling of oxidations via the cytochrome pathway, as shown by the inhibition of respiration of fertilized eggs by HCN and CO in contrast with the insensitivity of the unfertilized eggs to these agents (11). The increased oxygen consumption, added to an increased utilization of glycogen with the formation of an acid is an indication that during the fertilization process there is an increase of the oxidative phase of carbohydrate metabolism. Since the metabolism of carbohydrate in Arbacia eggs under anaerobic conditions ends with the formation of lactic acid, it is reasonable to conclude that the lactic acid comes from the reduction of pyruvic acid. (Arbacia eggs contain from 250 to 500 micrograms of diphosphopyridine nucleotide, the coenzyme for glycolysis, according to Jandorf and Krahl (12).) Hence, the oxidative phase must start either with the oxidation of pyruvic to acetic acid or with its carboxylation to oxaloacetic * An abstract of this work appeared in

Studies on the Respiration of Sea-Urchin Spermatozoa

“…Since, however, the presence of enzymes essential for the tricarboxylic acid cycle, succinic and malic dehydrogenase and fumarase, in sea-urchin spermatozoa has been demonstrated ( SUTO 1938, BALL andMEYERHOF 1940, GOLDINGER and BARRON 1946, SPIKES 1949, MOHRI 1937b, GHIRETTI and LIBONATI 1957, and further, the respiration of sea-urchin spermatozoa has been found to be inhibited by malonate and fluoroacetate (MOHRI 1957 b, c), the failure of cycle intermediates in increasing O2 uptake might be due to the fact that the surface of spermatozoa is relatively impermeable to these substrates. In order to increase the permeability of the spermatozoa to these substrates, an attempt has been made by SPIKES (1949), using esters of cycle intermediates such as ethyl citrate and ethyl succinate, but resulted in an inhibition of the 0 2 uptake, these esters probably acting as competitive inhibitors of the corresponding salts.…”

“…Since, however, the presence of enzymes essential for the tricarboxylic acid cycle, succinic and malic dehydrogenase and fumarase, in sea-urchin spermatozoa has been demonstrated ( SUTO 1938, BALL and MEYERHOF 1940, GOLDINGER and BARRON 1946, SPIKES 1949, MOHRI 1937 b, GHIRETTI and LIBONATI 1957, and further, the respiration of sea-urchin spermatozoa has been found to be inhibited by malonate and fluoroacetate (MOHRI 1957 b, c), the failure of cycle intermediates in increasing O2 uptake might be due to the fact that the surface of spermatozoa is relatively impermeable to these substrates.…”

Metabolic Activities and Cleavage of Eggs of the Sea Urchin, Arbacia Punctulata a Review, 1932-1949

“…Echinochrome is a substituted naphthoquinone (see below) capable of oxidizing reduced sulfhydryl groups which are known to be essential for oxidation of succinate and other substrates (Hopkins and Morgan, 1938;Barron and Singer, 1943). Earlier unsuccessful attempts to demonstrate oxidation of a-ketoglutarate (Goldinger and Barron, 1946) or succinate (Ball and Meyerhof, 1940;Ballentine, 1940;Goldinger and Barron, 1946) (1948). Pyocyanino and DPN were added as electron carriers and glucose was added as a supplemental substrate.…”