Abstract
The microsporidian spore extrusion apparatus activates with a calcium influx from Spraguea lophii spore wall/plasma membrane; this influx requires preconditioning with an extrasporular shift in medium pH to the alkaline in the presence of the polyanions mucin or polyglutamate. Undischarged S. lophii spores display calcium bound to the wall/plasma membrane with a characteristic calcium-chlorotetracycline fluorescence; this fluorescence declines significantly during spore discharge. S. lophii spores do not discharge when spore wall/plasma membrane calcium is removed with EGTA. Extrasporular mucin or polyglutamate and a pH shift to the alkaline appear to be necessary preconditions for the triggering of the influx of spore wall/plasma membrane-bound 45Ca2+. Ionophore A-23187 also effectively activates spore discharge without other extrasporular polyanions. Micromolar concentrations of the calcium antagonists lanthanum or verapamil prevent spore discharge, and micromolar concentrations of calmodulin inhibitors chlorpromazine and trifluroperazine prevent spore discharge. Calmodulin, visualized with a calmodulin antibody and a peroxidase conjugate, is localized particularly on the plasma membrane and the polaroplast membranes of the extrusion apparatus.
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- Graham R. C., Jr, Karnovsky M. J. The early stages of absorption of injected horseradish peroxidase in the proximal tubules of mouse kidney: ultrastructural cytochemistry by a new technique. J Histochem Cytochem. 1966 Apr;14(4):291–302. doi: 10.1177/14.4.291. [DOI] [PubMed] [Google Scholar]
- Hagiwara S., Byerly L. Calcium channel. Annu Rev Neurosci. 1981;4:69–125. doi: 10.1146/annurev.ne.04.030181.000441. [DOI] [PubMed] [Google Scholar]
- Levin R. M., Weiss B. Selective binding of antipsychotics and other psychoactive agents to the calcium-dependent activator of cyclic nucleotide phosphodiesterase. J Pharmacol Exp Ther. 1979 Mar;208(3):454–459. [PubMed] [Google Scholar]
- Louvard D., Reggio H., Warren G. Antibodies to the Golgi complex and the rough endoplasmic reticulum. J Cell Biol. 1982 Jan;92(1):92–107. doi: 10.1083/jcb.92.1.92. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nachshen D. A., Blaustein M. P. The effects of some organic "calcium antagonists" on calcium influx in presynaptic nerve terminals. Mol Pharmacol. 1979 Sep;16(2):576–586. [PubMed] [Google Scholar]
- Roufogalis B. D. Comparative studies on the membrane actions of depressant drugs: the role of lipophilicity in inhibition of brain sodium and potassium-stimulated ATPase. J Neurochem. 1975 Jan;24(1):51–61. doi: 10.1111/j.1471-4159.1975.tb07627.x. [DOI] [PubMed] [Google Scholar]
- Schauer R. Chemistry, metabolism, and biological functions of sialic acids. Adv Carbohydr Chem Biochem. 1982;40:131–234. doi: 10.1016/s0065-2318(08)60109-2. [DOI] [PubMed] [Google Scholar]
- Weidner E., Byrd W. The microsporidian spore invasion tube. II. Role of calcium in the activation of invasion tube discharge. J Cell Biol. 1982 Jun;93(3):970–975. doi: 10.1083/jcb.93.3.970. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weidner E. The microsporidian spore invasion tube. The ultrastructure, isolation, and characterization of the protein comprising the tube. J Cell Biol. 1976 Oct;71(1):23–34. doi: 10.1083/jcb.71.1.23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weidner E. Ultrastructural study of microsporidian invasion into cells. Z Parasitenkd. 1972;40(3):227–242. doi: 10.1007/BF00329623. [DOI] [PubMed] [Google Scholar]
- Wolniak S. M., Hepler P. K., Jackson W. T. Detection of the membrane-calcium distribution during mitosis in Haemanthus endosperm with chlorotetracycline. J Cell Biol. 1980 Oct;87(1):23–32. doi: 10.1083/jcb.87.1.23. [DOI] [PMC free article] [PubMed] [Google Scholar]