The Physiology of Sea-urchin Spermatozoa

نویسنده

  • LORD ROTHSCHILD
چکیده

Since Gray showed in 1928 that dilute suspensions of sea-urchin spermatozoa respire at a higher rate, per spermatozoon, than dense suspensions, evidence has been accumulating which suggests that sea-urchin spermatozoa are in different physiological conditions in suspensions of different densities. This paper is concerned with these differences and, in particular, with the effects of rigorous pH control on them. The expression ' different physiological conditions' has had a deeper significance in regard to sea-urchin spermatozoa than it would have if used to describe differences between dense and dilute suspensions of mammalian spermatozoa. In the latter, dilution at 37 C. causes irreversible damage of a pathological nature. Two examples of the alleged physiological differences between dense and dilute sea-urchin sperm suspensions are: (1) Nelson (1948) stated that usnic acid stimulated the respiration of dense suspensions (4-1 x io-i-i2 x io spermatozoa/ ml.)* by as much as 660 %, but totally inhibited the respiration of dilute suspensions (IO 8 -I-8 x io/ml.); (2) Rothschild (1948) reported that the inhibition of respiration by CO in the dark varied inversely with the density of the sperm suspension. Usnic acid is an antibiotic derived from lichens (Marshak, 1947); it inhibits the cleavage of sea-urchin eggs and their phosphorus uptake (Marshak & Halting, 1948), and stops the fusion of the male and female pronuclei (Marshak, 1949). Usnic acid also uncouples oxidation and phosphorylation (Johnson, Feldott & Lardy, 1950). Nelson's observations suggest the possibility that in dilute suspensions of sea-urchin spermatozoa phosphorylation and oxidation are to a certain extent uncoupled and that usnic acid may, therefore, not stimulate their oxidative processes; but that this is not so in dense suspensions, in which case usnic acid could cause an increase in their Oa uptake. Bearing in mind the insolubility of usnic acid in sea water and the problem of the permeability of intact cells to such substances, it seemed reasonable to test this hypothesis of 'uncoupling' by examining the effect of 2,4-dinitrophenol (DNP) on the O2 uptake of dense and dilute suspensions. Such experiments are described in this paper. Tyler & Horowitz (1937 a, 1938) showed that the stimulation of oxidation and the inhibition of cleavage by DNP in marine eggs is a function

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تاریخ انتشار 2005