Studies on the Respiration of Sea-Urchin Spermatozoa

Abstract

It has been reported that the tricarboxylic acid cycle intermediates have little or no effect on O2 uptake of spermatozoa of several sea-urchin species (SPIKES 1949, MOHRI 1957 a), except Arbaciu punctulata spermatozoa of which are said to show increased O2 uptake in the presence of succinate, a-ketoglutarate and glutamate (BARRON and GOLDINGER 1941 a, b). 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.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. In the experiments to be reported here, therefore, another method which might render the spermatozoa more permeable was tried and it was found that the use of a hypotonic medium is effective in allowing the cycle intermediates to increase the O2 uptake. MATERIAL AND METHODSThe material used in this work was the semen of Anthociduris 252

Endogenous substrate for energy metabolism and ultrastructural correlates in spermatozoa of the sea urchin Diadema setosum

“…The sea urchin spermatozoon consists of a head, a midpiece, and tail. The sperm head of D. setosum contains mainly nucleus, similar to those of other species of sea urchin (Afzelius and Mohri, 1966; tions reported by Mohri (1957). The failure to utilize phospholipids appears to be due to the low activity of phospholipase A, in D. setosum spermatozoa (Table 4).…”

“…Diadema setosum belongs to the order Diadematoida, which are primitive types of sea urchins in comparison with the orders Echinoida and Arbacioida (Shigei, 1974). Previous studies have shown that the phospholipid content of D. setosum spermatozoa decreases following incubation in seawater (Mohri, 1957). However, the D. setosum spermatozoa contain TG, as do the sea urchin spermatozoa of the order Arbacioida (Mita et al, 1994b).…”

Sea urchin fertilization in a warm, acidified and high pCO2 ocean across a range of sperm densities

“…pH 7.0-7.5) is used as a mechanism to reduce sperm respiration in the 12 gonad and seminal fluid with the internal pH (pHi) of sperm being pH ca. 6.8 (Chia and Bickell, 1983;Mita and Nakamura, 2001;Mohri and Yasumasu, 1963). The inhibitory effect of low pH on sperm motility is over ridden in nature by the respiratory dilution effect of seawater (increased oxygen tension) and by the egg jelly peptides that promote sperm motility at low pH (Brokaw, 1990;Chia and Bickell, 1983;Darszon et al, 2008;Ward et al, 1985).…”

Tubulin-dynein system in flagellar and ciliary movement

“…Since CO 2 inhibits both respiration and motility of the spermatozoa, 127) it is plausible that release from the high P CO 2 in the testis or in dry sperm by dilution with seawater causes an increase in intracellular pH (pH i ) which in turn activates dynein ATPase activity. 128) In fact, a temporary decrease in the content of ATP as well as that of phosphagen has been observed immediately after dilution.…”