A volatile inhibitor immobilizes sea urchin sperm in semen by depressing the intracellular pH
Sea urchin spermatozoa are normally immotile in semen, but motility can be initiated by increasing gas flow over the semen--for example, by blowing N2 gas over a thin layer of semen. This result indicates that sperm motility is not O2 limited and suggests that seminal fluid contains a volatile inhibitor of motility which is responsible for the paralysis of sperm in semen. This inhibitor might be carbon dioxide, which reversibly immobilizes sperm. /sup 31/P-NMR measurements of pH show that the sperm intracellular pH (pHi) increases by 0.36 pH unit upon dilution of semen into seawater. Since previous studies have shown that this magnitude of pH increase is sufficient to trigger sperm motility, we suggest that the volatile inhibitor is inhibiting sperm motility in semen by depressing the pHi. A simple hypothesis that explains these observations is that the volatile motility inhibitor is CO/sub 2/, which could acidify pHi as a diffusable weak acid. In this regard, sperm diluted into seawater release acid, and this acid release is related to the pHi increase and motility initiation. In fact, nearly half of the acid released by sperm upon dilution is volatile and may therefore be due to CO/sub 2/ efflux. Most of the acid, however, cannot be attributed to CO/sub 2/ release because it is not volatile. Thus, when sperm are diluted into seawater, they raise their pHi by releasing CO/sub 2/ and protons from the cytoplasm into the surrounding seawater.
- Research Organization:
- Department of Biological Sciences of Stanford University, Pacific Grove, California
- OSTI ID:
- 5621781
- Journal Information:
- Dev. Biol.; (United States), Vol. 98:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
BIOLOGICAL EFFECTS
MOBILITY
INHIBITION
SPERMATOZOA
NITROGEN
NUCLEAR MAGNETIC RESONANCE
OXYGEN
SEA URCHINS
SEAWATER
ANIMALS
AQUATIC ORGANISMS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ECHINODERMS
ELEMENTS
GAMETES
GERM CELLS
HYDROGEN COMPOUNDS
INVERTEBRATES
MAGNETIC RESONANCE
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RESONANCE
WATER
560304* - Chemicals Metabolism & Toxicology- Invertebrates- (-1987)