An immunofluorescence study on lectin binding sites in gametes of Ectocarpus siliculosus (Ectocarpales, Phaeophyceae)

Abstract

SUMMARY The distribution of binding sites for the lectins WGA, DSA. RCA I, PNA, AAA, MAA. SNA, GNA. and Con A in gametes of both sexes of the brown alga, Ectocarpus siliculosus (Dillw.) Lyngbye, was investigated by fluorescence microscopy. Digoxigenin‐conjugated lectins and an FITC‐anti‐digoxigenin antibody were used as a high sensitivity detection system. Organelles and other distinct cellular domains could be distinguished by their binding specificities. Glycoconjugates associated with one flagellum were found to be associated with the axoneme by lectin binding to isolated flagellar apparatuses. In addition, changes in the distribution of carbohydrate epitopes during the attachment of gametes to the substratum were revealed by differential lectin binding.

Repeated co-option of HMG-box genes for sex determination in brown algae and animals

“…Gamete fusion in Ectocarpus follows a stepwise process that begins with the attraction of male gametes to the pheromone ectocarpene produced by settled female gametes ( 47 ) and then proceeds with gamete recognition and cell-cell fusion ( 48 , 49 ). We examined the mating behavior of the apt and hmg1, hmg2, and hmg3 mutant lines in response to female gametes, using high-speed video microscopy.…”

Development and physiology of the brown alga Ectocarpus siliculosus: two centuries of research

“…There is evidence that cell‐to‐cell recognition between Ectocarpus gametes is mediated by N‐acetyl glucosamine residues exposed on the plasma membrane of the female gametes and that these residues are specifically recognized by a receptor on the male gamete (Schmid, 1993; Schmid et al ., 1994a). In addition, the lectins concanavalin A (Con A) and Aleuria aurantia agglutinin (AAA) bind specifically to the anterior flagella of Ectocarpus gametes and the molecules with which they interact also may be involved in the gamete recognition process (Maier & Schmid, 1995).…”

A TUBULAR MASTIGONEME‐RELATED PROTEIN, OCM1, ISOLATED FROM THE FLAGELLUM OF A CHROMOPHYTE ALGA,OCHROMONAS DANICA1

“…Figure 2, a and b, shows that FITC‐ConA strongly bound to the mastigonemes on both sides of the anterior flagellum in O. danica , whereas no fluorescence was detected on the posterior flagella, as in gametes of Ectocarpus (Maier and Schmid 1995). The cell body of O. danica was also strongly labeled by FITC‐ConA, showing that the cell body may contain many N‐linked glycoproteins.…”

“…Chen and Haines (1976), based on the results of periodic acid‐Schiff staining, demonstrated that the mastigoneme proteins of O. danica are glycoproteins. Maier and Schmid (1995) reported that some kinds of lectin (ConA: Canavalia ensiformis agglutinin; AAA: Aleuria aurantia agglutinin), carbohydrate‐binding proteins with high specificity and affinity, bind to mastigonemes on the anterior flagellum of the gametes of Ectocarpus siliculosus (Dillwyn) Lyngb (Phaeophyceae). In our experiment, ConA also bound to the mastigomenes of O. danica .…”

“…Fluorescein‐isothiocyanate‐conjugated concanavalin A labeling of mastigonemes. The mastigonemes of O. danica were detected by fluorescein‐isothiocyanate‐conjugated Concanavalin A (FITC‐ConA), according to the method of Maier and Schmid (1995) with slight modifications: O. danica cells were fixed with 1% glutaraldehyde in culture medium for 1 h at 23°C. After fixation, specimens were rinsed with PBS (137 mM NaCl, 8.10 mM NaHPO 4 , 2.68 mM KCl, 1.47 mM KH 2 PO 4 , pH 7.4) containing 1 mM Ca 2+ , 1 mM Mg 2+ , and 1 mM Mn 2+ and then directly labeled in 100 μg · mL −1 FITC‐ConA (Sigma‐Aldrich, St. Louis, MO, USA) in the same PBS solution for 60 min in darkness at 23°C.…”