Browsing by Author "DUPRE, E"

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    FINE-STRUCTURE OF THE MATURE SPERMATOZOON OF RHYNCHOCINETES-TYPUS CRUSTACEA DECAPODA
    (1983) DUPRE, E; BARROS, C
    R. typus spermatozoa obtained from the vas deferens have the shape of a round-headed nail. The head measures 30 .mu.m in diameter and 14 .mu.m of height. At the center of the flat face of the head emerges a single rigid spike of 53 .mu.m in length. Cross sections of this spike show that it has a wall of 0.4 .mu.m in thickness and a core of 0.6-0.8 .mu.m. The outer surface of the spike has a longitudinal striation. When the spermatozoa are placed in sea water it is possible to observe the unfolding of rays. The number of rays in different spermatozoa of the same individual varies from 9-13. Each ray is formed by a channel-like sheath that contains a rigid rod that occupies .apprx. 1/3 the length of the ray. This rod has a transverse striation with a periodicity of 185A. The rays are bound among them by a thin membranous sheet that is highly folded in vas deferens spermatozoa. At the distal end of each ray there is a rigid spine of 50 .mu.m in length. The nucleus is coplanar to the radial plane and it extends through the rays. The structure and ultrastructure of R. typus spermatozoa depart from that reported for spermatozoa of other Caridea species.
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    LOCALIZATION OF MICROFILAMENTS AND A TUBULIN-LIKE PROTEIN IN CRUSTACEAN (RHYNCHOCINETES-TYPUS) SPERMATOZOON
    (1991) PEREZ, C; ROCO, M; CASTRO, A; DUPRE, E; SCHATTEN, G; BARROS, C
    Sperm from the decapod crustacean Rhynchocinetes typus undergo dramatic shape changes as they pass from the vas deferens to seawater and interact with the oocyte envelopes. Using FITC-phalloidin and antitubulin antibodies, we were able to localize microfilaments and a tubulin-like protein in R. typus spermatozoon. Microfilaments and the tubulin-like protein were associated with the sperm rays and spines, but were absent at the spike and at its base. Folded and unfolded spermatozoa display similar fluorescence patterns. SDS-PAGE of whole spermatozoa and electrotransfer to nitrocellulose confirmed the presence of actin and two proteins at 97 kd and 120 kd that bind to tubulin antibodies (tubulin-like proteins). These results demonstrate the presence of actin, but not tubulin, and localize microfilaments in these sperm. It is proposed that this cytoskeletal component is active in sperm during crustacean fertilization.
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    SPERM-EGG INTERACTIONS IN THE SHRIMP RHYNCHOCINETES-TYPUS
    (1986) BARROS, C; DUPRE, E; VIVEROS, L
    Sperm-egg interaction in Rhynchocinetes typus was studied with the phase-contrast and scanning electron microscopes. R. typus spermatozoa present in the vas deferens have the shape of a round-headed nail. After contact with seawater it is possible to observe the unfolding of the rays of stellate arms, giving the spermatozoon the appearance of an inverted umbrella. From the center of the flat face of the umbrella emerges a spike with longitudinal striations. Ovarian eggs and spermatozoa were mixed in vitro by agitating them for two minutes in Millipore-filtered seawater. The first gamete contact was established by the spermatozoa through the tip of the spike, which exerted a lytic action on the egg envelopes. After the rigid spike was completely inside the egg, the rays became aligned parallel to each other and began to enter the eggs. Toward the final stages of ray entry, it was possible to observe fusion of the ray membranes with one another, and later the fusion process continued toward the tip of the radial spines. Concomitantly, the egg surface that surrounds the sperm swelled in a circular fashion and formed a fertilization cone. After the spermatozoa entry was complete, a scarlike mark appeared at the place on the egg surface through which penetration occurred. The whole penetration process was completed within 45-60 minutes.