Worm Breeder's Gazette 5(1): 26

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Vesicle Fusion, Pseudopod Extension and Amoeboid Motility are Induced in Nematode Spermatids by the Ionophore Monensin

G.A. Nelson, S. Ward

SUMMARY
The sodium and potassium transporting ionophore monensin induces the 
maturation of Caenorhabditis ds to 
spermatozoa in vitro.   Rearrangement of cytoplasm, fusion of 
membranous organelles with the plasma membrane, and growth of 
pseudopodia, all characteristic of in vivo spermiogenesis, occur 
within five minutes after exposure to monensin at concentrations of 0.
1-1.0  M.   This activation is dependent on external Na+ and K+ ions 
but not Ca2+ ions.  Monensin activated spermatozoa have normal 
morphology and normal amoeboid motility.   During activation 
spermatids twitch and rotate prior to pseudopod extension.   Analysis 
of intermediates by transmission and scanning electron microscopy 
reveals that the sequence of morphogenetic events leading from the 
spherical spermatid to the polarized spermatozoan is microvilli 
rearrangement and membranous organelle fusion, cytoplasmic 
polarization, then pseudopod extension.