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Sperm motility in the horseshoe crab 4. extracellular ions and intra cellular ph are not mediators of motility initiation


, : Sperm motility in the horseshoe crab 4. extracellular ions and intra cellular ph are not mediators of motility initiation. Gamete Research 6(4): 327-342

Upon dilution into sea water, Limulus spermatozoa undergo a brief flurry of motility (duration < 60 s), after which they are nonmotile until encountering a sperm motility initiating peptide (SMI) that emanates from eggs. Utilizing highly purified SMI extracts and simplified seawater formulations (from which individual ions were deleted), no specific extracellular ion is required for either dilution-initiated or SMI-initiated motility. Deletion of 1 ion (Na+) produced dilution-initiated motility of very long duration (several hours). When motility is initiated by SMI (in normal seawater) there is an increase in intracellular pH (pHi), as indicated by the fluorescent probe, 9-amino acridine; this pHi change is not a trigger for motility. As a more general method examining ion movements, the fluorescent probe diS-C3-(5) was used to qualitatively measure changes in the membrane potential of spermatozoa. Although crude SMI extracts caused membrane depolarization, further purification resulted in an almost complete separation of this activity from SMI, showing that SMI activation is apparently an electroneutral event. (The membrane-depolarizing factor has a MW > 30,000 and does not initiate acrosome reactions.) Experiments utilizing the ionophore A23187 [calcimycin] and Ca+2-blocking agents (verapamil and TMB-8 [8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate]) provided tentative evidence that mobilization of intracellular Ca+2 may be required for motility initiation. Neither changes in pHi nor the influx of specific extracellular ions are direct mediators of SMI-initiated motility; experiments with pharmacologic agents indicate a possible role for intracellular Ca+2.

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Related references

Clapper D.L.; Epel D., 1981: Isolation and utilization of a sperm motility initiating peptide in the horseshoe crab limulus polyphemus evidence for involvement of calcium ii but not intra cellular ph or membrane potential in motility initiation. Journal of Cell Biology 91(2 PART 2): 179A

Clapper, DL.; Brown, GG., 1980: Sperm motility in the horseshoe crab Limulus polyphemus L. 2. Partial characterization of a motility intitiating factor from eggs and the effects of inorganic cations on motility initiation. Egg extracts (obtained by washing intact Limulus eggs with either distilled water or artificial seawater, ASW) contain a sperm motility initiating factor (SMI). The SMI is heat stable (withstands boiling to dryness), passes through a dialysis memb...

Clapper, D.L.; Brown, G.G., 1980: Sperm motility in the horseshoe crab limulus polyphemus 2. partial characterization of a motility initiating factor from eggs and the effects of inorganic cations on motility initiation. Egg extracts (obtained by washing intact Limulus eggs with either distilled water or artificial seawater, ASW) contain a sperm motility initiating factor (SMI). The SMI is heat stable (withstands boiling to dryness), passes through a dialysis memb...

Clapper, D.L.; Brown, G.G., 1980: Sperm motility in the horseshoe crab, Limulus polyphemus L. II. Partial characterization of a motility initiating factor from eggs and the effects of inorganic cations on motility initiation. Developmental Biology 76(2): 350-357

Clapper, D.L.; Brown, G.G., 1980: Sperm motility in the horseshoe crab, Limulus polyphemus L. I. Sperm behavior near eggs and motility initiation by egg extracts. Limulus spermatozoa are nonmotile when spawned and become motile only after encountering a sperm motility initiating factor (SMI) exuded by the egg. SMI extracts (produced by washing intact eggs with distilled water, lyophilizing the supernatant t...

Clapper, D.L.; Brown, G.G., 1980: Sperm motility in the horseshoe crab limulus polyphemus 1. sperm behavior near eggs and motility initiation by egg extracts. Limulus spermatozoa are nonmotile when spawned and become motile only after encountering a sperm motility initiating factor (SMI) exuded by the egg. SMI extracts (produced by washing intact eggs with distilled water, lyophilizing the supernatant t...

Clapper, DL.; Brown, GG., 1980: Sperm motility in the horseshoe crab, Limulus polyphemus L. 1. Sperm behavior near eggs and motility initiation by egg extracts. Limulus spermatozoa are nonmotile when spawned and become motile only after encountering a sperm motility initiating factor (SMI) exuded by the egg. SMI extracts (produced by washing intact eggs with distilled water, lyophilizing the supernatant t...

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Clapper, D.L.; Lamothe, P.J.; Davis, J.A., 1985: Sperm motility in the horseshoe crab. Zinc removal mediates chelator initiation of motility. The Journal of Experimental Zoology 236: 91

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