ABSTRACT
Animals with external fertilization, as amphibians, store their sperm in a quiescent state in the testis. When spermatozoa are released into natural fertilization media, the hypotonic shock triggers activation of sperm motility. Rhinella (Bufo) arenarum sperm are immotile in artificial seminal plasma (ASP, resembling testicular plasma tonicity) but acquire in situ flagellar beating upon dilution. However, if components from the egg shelly coat are added to this medium, motility shifts to a progressive pattern. Recently, we have shown that the signal transduction pathway required for in situ motility activation involves a rise in intracellular cAMP through a transmembrane adenylyl cyclase and activation of PKA, mostly in the midpiece and in the sperm head. In this report, we demonstrate that activation of calcineurin (aka PP2B and PPP3) is required for the shift from in situ to progressive sperm motility. The effect of calcineurin is manifested by dephosphorylation of PKC substrates, and can be promoted by intracellular calcium rise by Ca(2+) ionophore. Both phosphorylated PKC substrates and calcineurin localized to the flagella, indicating a clear differentiation between compartmentalization of PKA and calcineurin pathways. Moreover, no crosstalk is observed between these signaling events, even though both pathways are required for progressive motility acquisition as discussed.
Subject(s)
Amphibian Proteins/metabolism , Bufo arenarum/metabolism , Calcineurin/metabolism , Protein Kinase C/metabolism , Signal Transduction , Sperm Motility , Spermatozoa/enzymology , Animals , Calcineurin Inhibitors , Calcium Ionophores/pharmacology , Cyclic AMP-Dependent Protein Kinases/metabolism , Enzyme Inhibitors/pharmacology , Flagella/enzymology , Male , Osmotic Pressure , Phosphorylation , Signal Transduction/drug effects , Sperm Midpiece/enzymology , Sperm Motility/drug effects , Sperm Tail/enzymology , Spermatozoa/drug effects , Substrate SpecificityABSTRACT
Ultrastructural cytochemical techniques were used for the localization of phosphatases in spermatid and spermatozoon, as well as in Sertoli cells of Odontophrynus cultripes (Amphibia, Anura, Leptodactylidae). Acid phosphatase was found in the acrosome. Thiamine pyrophosphatase was observed in the Golgi cisternae and in the tail spermatozoon surface. Glucose-6-phosphatase was located in the membrane complex of the acrosomal region. Already, in the Sertoli cells acid phosphatase was located in the lysosomes and glucose-6-phosphatase was observed in association with the endoplasmic reticulum and Golgi complex. These observations support the idea that various phosphatases may play some role in spermatid differentiation and in the interactions germ cells--Sertoli cells during spermiogenesis process
Subject(s)
Animals , Male , Acrosome/enzymology , Anura , Microscopy, Electron , Phosphoric Monoester Hydrolases/analysis , Sertoli Cells/enzymology , Sperm Tail/enzymology , Spermatids/enzymologyABSTRACT
Ultrastructural cytochemical techniques were used for the localization of phosphatases in spermatid and spermatozoon, as well as in Sertoli cells of Odontophrynus cultripes (Amphibia, Anura, Leptodactylidae). Acid phosphatase was found in the acrosome. Thiamine pyrophosphatase was observed in the Golgi cisternae and in the tail spermatozoon surface. Glucose-6-phosphatase was located in the membrane complex of the acrosomal region. Already, in the Sertoli cells acid phosphatase was located in the lysosomes and glucose-6-phosphatase was observed in association with the endoplasmic reticulum and Golgi complex. These observations support the idea that various phosphatases may play some role in spermatid differentiation and in the interactions germ cells--Sertoli cells during spermiogenesis process.
Subject(s)
Phosphoric Monoester Hydrolases/analysis , Sertoli Cells/enzymology , Spermatids/enzymology , Acrosome/enzymology , Acrosome/ultrastructure , Animals , Anura , Male , Microscopy, Electron , Sertoli Cells/ultrastructure , Sperm Tail/enzymology , Sperm Tail/ultrastructure , Spermatids/ultrastructureABSTRACT
The flagellum of Coelomera lanio has a single axoneme with a 9 + 9 + 2 axoneme pattern and the microtubules are linked to the E-PTA positive dinein arms. The electron-dense fibres between microtubules show a positive acid phosphatase reaction. A single E-PTA positive accessory body is seen flanking the axoneme, from which extends a puff-like corpuscle. On the opposite side of the accessory body, away from the axoneme, exists another puff-like corpuscle. The mitochondrial complex gives rise to two mitochondrial derivatives of different shapes and sizes. The major derivative possesses a paracrystalline corpuscle and the minor has an electron-dense area in the juxta-axonemal region. All these structures are involved in the mechanism of flagellar motility.
Subject(s)
Sperm Tail/ultrastructure , Alkaline Phosphatase/analysis , Animals , Coleoptera , Male , Microscopy, Electron , Microtubules/enzymology , Microtubules/ultrastructure , Mitochondria/ultrastructure , Morphogenesis , Sperm Tail/enzymologyABSTRACT
The cytochemical study of acid phosphatase in spermatic cells of Ceratitis capitata defines the enzimatically active sites, relating this enzyme with morphological modifications of the cell components during spermiogenesis. In the axoneme, acid phosphatase is associated with the metabolism of phosphates which promote flagellar motility. The enzymatic activity verified on the cytoplasmic membranes demonstrates the importance of this enzyme in the process of cellular differentiation.