Fertilization in the Medusan, Spirocodon saltatrix

Biological Bulletin (Impact Factor: 1.64). 01/1951; 99(3):412-5. DOI: 10.2307/1538471
Source: PubMed

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    • "Male gamete chemotaxis toward the ovule was first described in bracken fern (Pfeffer, 1884), and now it is widely observed from algae (Maier and Müller, 1986) to flowering plants (Okuda et al., 2009) and fungi (Machlis, 1973; Pommerville and Olson, 1987). In animals, sperm chemotaxis toward the egg was first observed in the hydrozoan Spirocodon saltatrix (Dan, 1950) and such attraction ability is now widely recognized in marine invertebrates—from cnidarians (Miller, 1966) to ascidians (Miller, 1985b; Cosson, 1990)—and in vertebrates—from fish (Suzuki, 1958; 1959; Pillai et al., 1993; Oda et al., 1995) to humans (Eisenbach, 1999; Yanagimachi et al., 2013). The sperm-guiding factor present in the micropyle area of the egg of the teleost and rosy barb has also been described (Amanze and Iyengar, 1990). "
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    ABSTRACT: Egg-derived sperm-activating factors and attractants activate sperm motility and attract the sperm, respectively. These phenomena constitute the first communication signaling between males and females in the process of fertilization in many animals and plants, and in many cases, these are species-specific events. Thus, sperm motility activation and chemotaxis may act as a safety process for the authentication between conspecific egg and sperm, and help to prevent crossbreeding. Here, we examine species-specificity of sperm motility activation and chemotaxis in the ascidians belonging to the order Phlebobranchiata: Ciona intestinalis, Ciona savignyi, Phallusia mammillata, Phallusia nigra, and Ascidia sydneiensis. Cross-reactivity in both motility activation and chemotaxis of sperm was not observed between C. savignyi and P. mammillata, or between A. sydneiensis and Phallusia spp. However, there is a "one way" (no reciprocity) cross-reaction between P. mammillata and P. nigra in sperm activation, and between C. savignyi and A. sydneiensis in sperm chemotaxis. Furthermore, the level of activity is different, even when cross-reaction is observed. Thus, sperm motility activation and chemotaxis are neither "species-" nor "genus-" specific phenomena among the ascidian species. Moreover, the interaction between the sperm-activating and sperm-attracting factors (SAAFs) in the ascidian species and the SAAF receptors on the sperm cells are not all-or-none responses.
    Full-text · Article · Aug 2013 · Biological Bulletin
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    • "In many animals, the egg exhibits chemoattraction to spermatozoa prior to fertilization. Sperm attraction was first observed in cnidarians: Dan (1950) first described sperm chemotaxis in the hydromedusae Spirocodon saltatrix, and since then, the phenomenon has been observed in a variety of animals from sponge to human (Miller 1985b; Cosson 1990; Eisenbach 1999; Morisawa & Yoshida 2005). The species-specific sperm attraction that has been observed in hydroids (Miller 1979), echinoderms (Miller 1985a), and ascidians (Miller 1982; Yoshida et al. 1993; Morisawa & Yoshida 2005) suggests that sperm attraction by an egg facilitates the selective accumulation of sperm of the same species, which ensures fertilization. "
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    ABSTRACT: Sperm chemotaxis toward an egg is observed in many animals, and the control of sperm-attracting activity is thought to play an important role in ensuring fertilization. However, the mechanism underlying the release of a sperm attractant from an egg is still obscure. In this study, we examined the systems involved in the release of sperm-activating and sperm-attracting factor (SAAF), which is the sperm attractant of the ascidian Ciona intestinalis. Here, we show that the egg acquires sperm-attracting activity after germinal vesicle breakdown. Further, since the cytoplasmic extracts of immature oocytes exhibit no sperm-attracting activity, the SAAF in oocytes may be activated after germinal vesicle breakdown. We found 13 SAAF-binding proteins in an egg plasma membrane extract and identified five proteins by proteomic analysis: valosin-containing protein (VCP)/p97, proteasome alpha 2 subunit, MGC97756 protein, proteasome subunit Y, and beta-tubulin. In particular, the interaction between VCP/p97 and SAAF was confirmed by a pull-down assay. VCP/p97 is initially localized in the germinal vesicle, and during oocyte maturation, it shifts to the endoplasmic reticulum in the cortical regions. Thus, VCP/p97 is a potential modulator of SAAF release from the egg.
    Full-text · Article · Nov 2008 · Development Growth and Regeneration
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    ABSTRACT: The pre-fertilization behavior of the sperm of the thecate hydroids Campanularia flexuosa and Campanularia calceolifera has been observed and recorded by means of dark-field cinephotomicrography. The sperm of both species activate and aggregate homotypically around the aperture of the female gonangium. Plots of the paths of sperm approaching the aperture show that the aggregations are the result of directed turning movements and not of so-called trap-actions or an increased random turning of the spermatozoa. An aperture-associated tissue of ectoderm origin has been found to produce the attractive substances.Active sea water and alcohol extracts of female gonangia of C. calceolifera have been prepared. The substance affects sperm in the same ways as the material released by the female gonangium. The active material is heat stable, non-volatile, dialyzable, polar, and appears to be a single molecular species of less than 5,000 mw. Injection of these extracts into sperm suspensions by means of a micropipette produces activation and aggregation of only the sperm of C. calceolifera about the pipette tip. If agar impregnated with the chemotactant is used as a source, the sperm are seen to orient with considerable accuracy. Extraction of C. flexuosa female gonangia has not yielded active extracts.These results demonstrate that chemotaxis does occur during fertilization in an animal. The mechanism of the reaction remains to be determined.
    No preview · Article · Jun 1966 · Journal of Experimental Zoology
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