Plasma Membrane Domains and the Site of Sperm Entrance in Discoglossus pictus (Anura) Eggs |
| |
Authors: | Roberto Gualtieri Gennaro Cafiero Piero Andreuccetti |
| |
Affiliation: | Dipartimento di Biologia Evolutiva a Comparata, Universitàdi Napoli, via Mezzocannone No. 8, 80134 Napoli, Italy.;Centro Interdipartimentale di Ricerca sulle Ultrastrutture Biologiche, via Foria No. 222, 80139 Napoli, Italy. |
| |
Abstract: | Freeze-fracture quantitative analysis reveals three different plasma membrane (PM) domains in the unfertilized egg of the anuran Discoglossus pictus . One of these is specific to the sperm entrance site (D1). where the plasma membrane shows a larger number of intramembranous particles (IMP) than the rest of the egg surface. Such an increment is due to a markedly higher number of the IMPs anchored to the P-face. The two other domains (D2 and D3) are characterized by a lower IMP density at the P-face with respect to D1. The IMP density decreased within 10 min after fertilization by about 33% in all domains observed, probably due to the insertion of new membrane through exocytosis. The possibility that the IMPs located in D1 may represent putative plasma membrane proteins playing a role in sperm-egg interaction and/or in egg activation is discussed. |
| |
Keywords: | |
|
|