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Female plant of Aglaothamnion oosumiense developing carpogonia and hair cells. Note the spermatia attached to the trichogyne and hair cell (cb, carpogonial branch; hc, hair cell; tr, trichogyne; scale bar: 20 μ m).
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The binding of fluorescein isothiocyanate (FITC) conjugated lectins to gametes of Aglaothamnion oosumiense Itono during fertilization was studied by the use of confocal microscopy. The physiological effects of lectins and carbohydrates on gamete binding were also examined. Four different lectins, concanavalin A (ConA), soybean agglutinin (SBA), Dol...
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... female reproductive structure of Aglaothamnion oosumiense is composed of four-celled carpogonial branches with a single long trichogyne (i.e., the spermatium-receptive structure) terminating the carpogonium ( Figure 1). In the presence of female plants, spermatia of Aglaothamnion oosumiense bound only to trichogynes and hair cells, and very few spermatia ( < 3%) were observed in contact with any other parts of the female thallus. Trichogynes and hair cells were often located close to each other, and spermatia bound to both cells. Spermatial attachment could be detected within a few seconds of adding female plants, and was com- pleted within 30 min – 1 h according to spermatial concentration. The percentage of spermatial binding to trichogynes was proportional to the relative concentration of spermatia (Figure 2). Maximum percentage binding (96.9%) was attained at approximately 200 spermatia per trichogyne (2 × 10 4 spermatia ml − 1 ), and half maximum binding occurred at a relative concentration of 100 spermatia per trichogyne. There was little increase of binding percentage at over 150 spermatia per trichogyne. The spermatium was composed of two distinct parts, an ovoid spermatial body and two spermatial appendages projecting from each distal end of spermatial body (Figures 3A, B). The carbohydrate moieties on spermatial surfaces were visualized using fluorescein- labelled lectins (Table 1; Figures 3C–F). Four lectins, concanavalin A (ConA), soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA) and wheat germ agglutinin (WGA) bound to the surface of released spermatia (Figures 3C–F). Each lectin labelled a different region of the spermatium. ConA bound mainly to the surface of the spermatial body but did not bind to the spermatial appendages (Figure 3C). SBA and DBA bound only to the spermatial appendages but SBA labelling was more intensive than DBA (Figures 3D, E). This difference in labelling intensity may be due to slight difference in sugar moiety of the two lectins; SBA bound to N -acetyl-galactosamine while DBA bound more specifically to α - N -acetyl-galactosamine (Table 1). WGA labelled the spermatial body but was different from ConA in binding more strongly to the narrow region connecting the spermatial body and appendages (Figure 3F). Thus, each lectin receptors had a unique distribution. The carpogonium and trichogyne did not bind to the lectins, but thay stained with calcofluor white (Table 1). Non-specific binding was not observed in any of the lectins applied (Figures 1G–J). Changes in the distribution of lectin receptors were observed according to stages of fertilization (Figure 4). Sixty min after spermatial attachment to trichogynes, the spermatial wall protruded toward the trichogyne and spermatia changed from ovoid to mushroom-shaped (Figures 4A, B). At this time, the ConA receptors on the spermatial surface accumulated at the area contacting the trichogyne (Figure 4B ), while the SBA receptors did not change their distribution (Figure 4E ). The distribution of WGA receptors was of interest because they appeared to move towards the contacting area with trichogyne (Figures 4G, H). The fertilization canal (FC) between spermatia and trichogyne developed around 120 min after spermatial binding (Figure 4C). The ConA receptors distributed along the surface of the fertilization canal as well as the spermatial body (Figure 4C ), but WGA receptors were found only on the fertilization canal (Figure 4I ). The SBA and DBA receptors did not show any change in distribution during fertilization (Figures 4D –F ). The percentage of spermatial attachment to trichogynes was assayed after pre-incubation of spermatia or trichogynes with various carbohydrates and lectins (Table 2). The binding of spermatia to trichogynes of Aglaothamnion oosumiense was inhibited by the lectins ConA and SBA, and their complementary carbohydrates, D -glucose and N -acetyl-galactosamine, respectively. SBA inhibited gamete binding more strongly than ConA (Table 2). When spermatia were pretreated with both lectins at the same time, spermatial binding to trichogynes was further reduced. WGA and DBA were less inhibitory for spermatial binding to trichogynes than ConA and SBA (Table 2). The inhibitory effects of the latter lectins were partially reversed (to 80-90% of controls) by addition of complementary carbohydrates. Trichogynes preincubated with D -glucose and N acetyl-galactosamine had inhibition of spermatium- trichogyne binding, but the inhibitory effect increased when the two sugars were used simultaneously (Table 2). Although ConA binds more strongly to D mannose than to D -glucose, spermatium-trichogyne binding was not inhibited by D -mannose. The average number of spermatia attached to trichogynes was also affected by preincubation of spermatia or trichogynes with lectins and sugars. When spermatia were preincubated with both ConA and SBA at the same time, the average number of attached spermatia was reduced to almost one sixth of control. The results were consistent with the percentage of spermatial attachment to trichogynes. Our data suggest that gamete recognition in nion oosumiense is mediated by a double-docking recognition process based on the interaction of two carbohydrate moieties with their complementary receptors (lectin-like molecules). Surfaces of spermatial body and appendages have two types of glycoconjugates specific to ConA and SBA, respectively, while those of trichogynes possess the complementary lectin-like receptors. Therefore, there are at least two sets of carbohydrate-receptor systems involved in gamete recognition in this species. The distribution of SBA receptors did not change during the fertilization process suggesting that the mo- lecule serves only for gamete recognition and binding. The ConA receptors, however, accumulated along the fertilization canal (FC) implying their involvement in FC development. The behavior of WGA receptors during the fertilization is of interest because they appeared to move from the distal ends to the center of the spermatia, and accumulate on the fertilization canal. This movement of WGA receptors may be necessary for the development of the fertilization canal and for gamete membrane fusion. The lectin SBA which bound to spermatial appendages showed a stronger inhibitory effect on gamete binding than ConA. This result may support our pre- vious suggestion that the primary role of spermatial appendages is in spermatial binding to trichogynes (Kim et al., 1996). Magruder (1984) reported selective spermatial binding to trichogynes and vegetative hair cells in Aglaothamnion neglectum and suggested that spermatia of this species may first attach to hair cells and later transfer to a nearby trichogyne. ...
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Aberrant sialylation is accepted as a carcinogenic biomarker. In previous work, fluorescently labeled wheat germ agglutinin (WGA) distinguished between cancerous and normal oral biopsies. The purpose of this study was to investigate WGA-fluorescein isothiocyanate (FITC) as a point-of-care tool for detecting oral malignant and dysplasti...
The interaction between lectins and their specific binding sites is believed to play a
critical role in fertilization in animals and some lower plants. However, for higher
plants there is no information on lectins or their binding sites related to female
gametes and fertilization. The present work was designed as a first attempt to reveal
the gener...
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... As known from the literature data, disorder content increases with the biological complexity during evolution [87,90,96,97]. Still little is known about the physiological roles of algal lectins, besides participation in cell-cell recognition during fertilization of some red and brown algae [98], as well as participation in responsiveness to the environmental factors [99] and photosynthesis [89]. Aleksidze et al. [100] reported that lectin of chloroplast thylakoids is considered a functional link connecting the light and dark phases of photosynthesis. ...
Photosynthetic microorganisms, specifically cyanobacteria and microalgae, can synthesize a vast array of biologically active molecules, such as lectins, that have great potential for various biotechnological and biomedical applications. However, since the structures of these proteins are not well established, likely due to the presence of intrinsically disordered regions, our ability to better understand their functionality is hampered. We embarked on a study of the carbohydrate recognition domain (CRD), intrinsically disordered regions (IDRs), amino acidic composition, as well as and functional motifs in lectins from cyanobacteria of the genus Arthrospira and microalgae Chlorella and Dunaliella genus using a combination of bioinformatics techniques. This search revealed the presence of five distinctive CRD types differently distributed between the genera. Most CRDs displayed a group-specific distribution, except to C. sorokiniana possessing distinctive CRD probably due to its specific lifestyle. We also found that all CRDs contain short IDRs. Bacterial lectin of Arthrospira prokarionte showed lower intrinsic disorder and proline content when compared to the lectins from the eukaryotic microalgae (Chlorella and Dunaliella). Among the important functions predicted in all lectins were several specific motifs, which directly interacts with proteins involved in the cell-cycle control and which may be used for pharmaceutical purposes. Since the aforementioned properties of each type of lectin were investigated in silico, they need experimental confirmation. The results of our study provide an overview of the distribution of CRD, IDRs, and functional motifs within lectin from the commercially important microalgae.
... advantage of existing water movement as they have nonmotile gametes. Spermatia only bind to female trichogynes through a specific lectin-carbohydrate complementary system (Kim and Fritz 1993b, Kim et al. 1995, Kim and Kim, 1999b. To compensate the inefficiency of fertilization resulted from non-motility of gametes, red algae have a complicated life cycle involving parasitic carposporophyte on female gametophyte (Searles 1980). ...
... In red algae, the spermatial attachment to the female trichogyne, the receptive protuberance of the carpogonium, is mediated by spermatial appendages and female specific lectin (Shim et al. 2012). Kim and Kim (1999) have shown that receptors of wheat germ agglutinin (WGA) bound to N-acetylglucosamine (GlcNAc) were localized in the spermatia, especially in the narrow region connecting the spermatial body and appendages, and moved towards the contracting area with the trichogyne, suggesting that WGA receptors may be necessary for gamete membrane fusion in the red alga Aglaothamnion oosumiense. In addition, WGA bound to the mucilage of carpospores in Pyropia spiralis is responsible for carpospore settlement to the substratum and the protection of the spores until cell wall deposition (Ouriques et al. 2012). ...
The marine red algal genus Pyropia, class Bangiophyceae, includes dioecious and monoecious species; however, the molecular mechanisms underlying control of their sexual reproduction are still poorly understood. In the present study, we demonstrated that application of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), promoted the formation of spermatangia and parthenosporangia in male and female gametophytes, respectively, of the dioecious species Pyropia pseudolinearis. In addition, we determined expression profiles of ACC-responsive genes in the gametophytes during sexual reproduction using RNA-Seq and quantitative real-time PCR (qRT-PCR). Genes involved in the regulation of cell division and cell wall organization, such as high-mobility group (PpHMG) and glycosyltransferase family (PpGT14), were found to be upregulated in male and female gametophytes treated with ACC. In addition, the relatively rapid ACC-response of the vesicular-trafficking-related genes, flotillin (PpFLOT), charged multivesicular body protein 5 (PpCHMP5), and peptidase family S8 (PpS8) was shown to occur during male and female sexual reproduction. Expression levels of these six genes in the monoecious species P. yezoensis, which are homologs to ACC-responsive genes in P. pseudolinearis, also increased in gametophytes treated with ACC. These findings could provide new insights into the ACC-regulation of the sexual life cycle in Pyropia species.
... As such, lectins have been introduced to investigate the nature of the cell surface including higher plants and seaweeds, mainly with respect to cell-cell interaction (Surek and Sengbusch, 1981;Sengbusch et al., 1982). The mechanism underlying the recognition of gametes can also be characterized with the use of lectins (Kim and Fritz, 1993;Kim and Kim, 1999). ...
Spore release is the primary means of dispersion employed by red algae, and it provides insight into the elements linking the stages of their life history. In most red algae, spores are released within a sheath-like envelope of mucilage, which is responsible for their primary attachment. However, few studies have characterized the polysaccharides involved in the adhesion of seaweed spores. Therefore, in this paper, the process of spore germination and adhesion in Porphyra spiralis var. amplifolia is described, as representative of the germination pattern of the Naccaria type. Using FITC-labeled lectins, we discovered high concentrations of α-D-mannose, α-D-glucose and β-D-galactose in the mucilage. The germ tube reacted with RCA-FITC, indicating the presence β-D-galactose, and the rhizoidal cells showed the presence of α-D-mannose, α-D-glucose and β-D-galactose, indicating their importance to substrate adhesion. Using light and transmission electron microscopy, we also conducted an analysis of spore ultrastructure. We found that the differentiation of a vacuole in the spore is one of the most important processes marking the initial stage of germination. Thus, as the degree of vacuolation increases, whole cell contents move towards the germ tube, which undergoes several successive divisions forming the sporophytic phase. Therefore, we can conclude that germination in Porphyra spiralis var. amplifolia is characterized by (1) the fixation of carpospores in the substrate by sugars present in the mucilage and (2) the polarization of cell contents by the processes of vacuolization and germ tube formation.
... Magruder (1984) demonstrated that spermatia from Aglaothamnion cordatum (as A. neglectum) specifically bind with trichogynes and hairs of female thalli, and that fimbriate cone-shaped appendages projecting from each end of the spermatium are responsible for the initial binding with trichogynes. The lectin-/carbohydrates-binding experiments of Ceramiacean species suggested that the attachment of spermatia to trichogynes is mediated by particular carbohydrates on spermatial surface and complementary carbohydrates-binding receptors on trichogynes (Kim and Fritz, 1993;Kim et al., 1996;Kim and Kim, 1999). In Antithamnion sparsum, d-mannose and l-fucose were involved in gamete recognition, whereas the latter was not involved in Aglaothamnion oosumiense (Kim et al., 1996;Kim and Kim, 1999). ...
... The lectin-/carbohydrates-binding experiments of Ceramiacean species suggested that the attachment of spermatia to trichogynes is mediated by particular carbohydrates on spermatial surface and complementary carbohydrates-binding receptors on trichogynes (Kim and Fritz, 1993;Kim et al., 1996;Kim and Kim, 1999). In Antithamnion sparsum, d-mannose and l-fucose were involved in gamete recognition, whereas the latter was not involved in Aglaothamnion oosumiense (Kim et al., 1996;Kim and Kim, 1999). Although these glycoproteins must be important for fertilization, which can be blocked by adding the complimentary sugars or lectins, it is still uncertain whether these glycoproteins are responsible for species recognition. ...
Allopatric speciation is the most widely accepted model proposed for speciation: once a population is divided by extrinsic
barriers, genetic flow is interrupted between these disjunct subpopulations, and reproductive isolation is established as
a by-product of the accumulation of genetic changes in these isolated populations. According to the biological species concept
(Mayr, 1942), the evolution of reproductive isolation is a defining characteristic of speciation, and reproductive isolation
contributes to the diversification of species by creating genetically independent lineages. It had been generally thought
that isolation is more difficult in marine populations, with frequent gene flow over large distances (Hoffmann, 1987; van
den Hoek, 1987; Norton, 1992; Shanks et al., 2003), as there seem to be far fewer extrinsic barriers in marine environments
than in terrestrial ones (Palumbi, 1994). Such attributes are considered to limit the isolation of a species into allopatric
populations less frequently, making allopatric speciation rarer (Mayr, 1954). However, recent molecular analyses have revealed
great genetic divergences among/within populations in various marine organisms, including macroalgae, and thus, the generalization
that speciation must be rare in marine habitats appears to be incorrect.
... Although there are few studies on the environmental factors inducing conjugation in the zygnematacean species (Grote 1977; Simons et al. 1984; Stabenau and Saeftel 1989; Kato and Ooshima 1997), the key factors which trigger the conjugation and the mechanism of recognition between the compatible filaments are still unknown (Kim et al. 2007). Cell surface carbohydrates are highly suitable for encoding biological information because of their complexity and structural diversity, and hence they have been reported as primary markers for cell-cell recognition events in many organisms ( Lis 1993, Kim and Kim 1999). Such recognition systems depend on the complementary binding between carbohydrate moieties of a glycoconjugate on one cell with a lectin protein on another cell (Sharon and Lis 1989; Chrispeels and Raikhel 1991; Kim and Kim 1999; Kim et al. 2005). ...
... Cell surface carbohydrates are highly suitable for encoding biological information because of their complexity and structural diversity, and hence they have been reported as primary markers for cell-cell recognition events in many organisms ( Lis 1993, Kim and Kim 1999). Such recognition systems depend on the complementary binding between carbohydrate moieties of a glycoconjugate on one cell with a lectin protein on another cell (Sharon and Lis 1989; Chrispeels and Raikhel 1991; Kim and Kim 1999; Kim et al. 2005). Because of their sugar-binding properties, fluoresceinlabeled lectins have been used as a powerful tool to analyze the characteristics and the distribution of cell surface carbohydrates in many organisms (e.g. ...
... Because of their sugar-binding properties, fluoresceinlabeled lectins have been used as a powerful tool to analyze the characteristics and the distribution of cell surface carbohydrates in many organisms (e.g. Wassarman 1987; Sharon and Lis 1989; Karlsson 1991; Kim and Fritz 1993a, b; Kim et al. 1996; Kim and Kim 1999). Cheli and De Vecchi (1989) showed that the extracellular mucilage of Spirogyra filaments disappeared during conjugation and some glycoproteinaceous materials were accumulated in the cell wall of the developing conjugation papilla, suggesting that the chemical composition in cell surface changed during the process. ...
A low temperature up-regulated gene was isolated from Spirogyra varians using the differentially expressed gene method. The full cDNA sequence consisted of 1798 bp with an open reading frame of 1560 bp encoding 520 amino acid residues, which had neither a cleavage site nor a signal peptide. The deduced amino acid sequence was highly similar to the bi-functional 3-dehydroquinate dehydratase/shikimate dehydrogenase (DHQ/SDH) gene of higher plants. As the gene was cold regulated, we named it SVCR3 (Spirogyra varians cold regulated gene). SVCR3 had two conserved domains of DHQase I and SDH (AroE), as well as a shikimate-binding site as found in other DHQ/SDH genes. Northern blot analysis showed that SVCR3 was up-regulated at 4°C. When combined with light (>50 μmol photon m-2 s-1) the expression of SVCR3 increased more at 4°C, but the expression was not affected by light intensity alone up to 200 μmol photon m-2 s-1 at temperatures higher than 10°C. Using the zymogram method (which is a visualization method for gel areas containing specific enzymes based on chromogenic reactions), we showed that there were three isozymes of DHQ/SDH in Spirogyra varians. This is the first report of DHQ/SDH-like gene regulation by cold stress.
... Although there are few studies on the environmental factors inducing conjugation in the zygnematacean species (Grote 1977; Simons et al. 1984; Stabenau and Saeftel 1989; Kato and Ooshima 1997), the key factors which trigger the conjugation and the mechanism of recognition between the compatible filaments are still unknown (Kim et al. 2007). Cell surface carbohydrates are highly suitable for encoding biological information because of their complexity and structural diversity, and hence they have been reported as primary markers for cell-cell recognition events in many organisms ( Lis 1993, Kim and Kim 1999). Such recognition systems depend on the complementary binding between carbohydrate moieties of a glycoconjugate on one cell with a lectin protein on another cell (Sharon and Lis 1989; Chrispeels and Raikhel 1991; Kim and Kim 1999; Kim et al. 2005). ...
... Cell surface carbohydrates are highly suitable for encoding biological information because of their complexity and structural diversity, and hence they have been reported as primary markers for cell-cell recognition events in many organisms ( Lis 1993, Kim and Kim 1999). Such recognition systems depend on the complementary binding between carbohydrate moieties of a glycoconjugate on one cell with a lectin protein on another cell (Sharon and Lis 1989; Chrispeels and Raikhel 1991; Kim and Kim 1999; Kim et al. 2005). Because of their sugar-binding properties, fluoresceinlabeled lectins have been used as a powerful tool to analyze the characteristics and the distribution of cell surface carbohydrates in many organisms (e.g. ...
... Because of their sugar-binding properties, fluoresceinlabeled lectins have been used as a powerful tool to analyze the characteristics and the distribution of cell surface carbohydrates in many organisms (e.g. Wassarman 1987; Sharon and Lis 1989; Karlsson 1991; Kim and Fritz 1993a, b; Kim et al. 1996; Kim and Kim 1999). Cheli and De Vecchi (1989) showed that the extracellular mucilage of Spirogyra filaments disappeared during conjugation and some glycoproteinaceous materials were accumulated in the cell wall of the developing conjugation papilla, suggesting that the chemical composition in cell surface changed during the process. ...
The conjugation processes of a filamentous freshwater green alga Spirogyra varians were examined using FITC-lectins. Conjugation comprised five steps: 1) aligning with adjacent filaments, 2) formation of conjugation protru-sion (papilla), 3) fusion of the protrusions, 4) formation of conjugation tube,and 5) formation of zygotes. Three lectins, ConA, RCA and UEA, showed considerable labeling during the progression of conjuation. FITC-ConA labeled the surfaces of filaments throughout the whole conjugation processes. FITC-RCA labeling was observed at the conjugation protrusions only after the papilla formation. Strong labeling continued until formationg of zygotes at the contacting area where the conjugation tube developed, but no labeling was detected on the surface of vegetative filaments. The labeling decreased gradually over time and disappeared when zygotes were formed. FITC-UEA showed similar labeling pattern with FITC-RCA except that weak labeling remained after zygote formation. Inhibition experiments using RCA, UEA which are complementary to sugars L-fucose and D-galactose, showed considerable decrease of conjugation (
... The lack of any shared sex-specific proteins across all isolates may be a reflection of the known rapid evolution of sex-specific proteins, principally of proteins involved in gamete recognition). An understanding of the genetics and molecular mechanisms of sex recognition in red algae is at very early stages (Kim et al. 1996, Lee et al. 1998, Kim and Kim 1999, Brodie and Zuccarello 2007 ). This system of wellcharacterized culture isolates of Bostrychia may lend itself to these studies, and this work is being pursued at the moment. ...
A comparison of the proteome of eight genetically well-characterized isolates of the Bostrychia radicans (Mont.) Mont./B. moritziana (Sond. ex Kütz.) J. Agardh species complex was undertaken to establish if genetic relationships among them can be determined using proteome data. Genetic distances were calculated on the basis of common and distinct spots in two-dimensional gel electrophoresis (2-DE). Proteomes of the male and female plants of each population were compared to analyze the range of genetic difference within an isolate. Haploid male and female plants of the same species had 3.7%–7.1% sex-specific proteins. The degree of similarity of the proteome was consistent with previous DNA sequence data and sexual compatibility studies between the isolates. Two sexually compatible isolates from Venezuela showed a pair-wise distance ranging from 0.14 to 0.21. The isolates from Mexico and Venezuela, which were partially compatible, showed a maximum pair-wise distance of 0.26. A high level of genetic difference was found among isolates that were sexually incompatible. The isolate from Brazil was reproductively isolated from the Mexico and Venezuela isolates and showed a maximum pair-wise distance of 0.65 and 0.58, respectively. Comparative proteomics may be helpful for studying genetic distances among algal samples, if intraisolate variation (gene expression) can be minimized or tested.
... Cell surface carbohydrates are highly suitable for encoding biological information because of their complexity and structural diversity, and hence they have been reported as primary markers for cell–cell recognition events in many organisms (Sharon & Lis 1993). Such recognition systems depend on the complementary binding between carbohydrate moieties of a glycoconjugate on one cell with a lectin protein on another cell (Sharon & Lis 1989; Chrispeels & Raikhel 1991; Ridge et al. 1998; Kim & Kim 1999; Kim et al. 2006). Because of their sugar-binding properties, fluorescein-labeled lectins have been used as a powerful tool to analyze the characteristics and the distribution of cell surface carbohydrates in many organisms (e.g. ...
... Because of their sugar-binding properties, fluorescein-labeled lectins have been used as a powerful tool to analyze the characteristics and the distribution of cell surface carbohydrates in many organisms (e.g. Wassarman 1987; Sharon & Lis 1989; Karlsson 1991; Kim & Fritz 1993a,b; Kim et al. 1996; Kim & Kim 1999). In an elaborate ultrastructural study, Cheli and De Vecchi (1989) showed that the extracellular mucilage of Spirogyra filaments disappeared during conjugation and some glycoproteinaceous materials were accumulated in the cell wall of the developing conjugation papilla, suggesting that the chemical composition in the cell surface changed during the process. ...
The changes of cell surface carbohydrates were examined with FITC (fluorescein isothiocyanate)-labeled lectins during the conjugation process of the green alga Zygnema cruciatum. The Ulex europaeus agglutinin (UEA)-specific materials were detected consistently on the surface of vegetative cells, but were absent on the surface of protruding papillae or conjugation tube. The tips of male and female papillae were labeled with soybean agglutinin (SBA) and peanut agglutinin (PNA) during conjugation. The SBA- and PNA-specific materials appeared first at the tip of male papillae and began to accumulate on the surface of female papillae. No labeling of these lectins was detected on the surface of vegetative filaments throughout the conjugation process. FITC-ConA (Concanavalin A) and FITC-RCA (Ricinus communis agglutinin) did not label the vegetative filaments of Z. cruciatum, but a trace labeling of these lectins was observed on the surface of some swollen papillae occasionally. Blocking experiments with various lectins showed that these SBA- and PNA-specific glycoconjugates might be involved in the signaling between male and female papillae.
... To date, little is known about the intrinsic biological roles of algal lectins. There are some indirect evidences of a lectin–carbohydrate complementary system involved in gamete recognition during fertilization of some red and brown algae (Kim and Fritz 1993a, b, Schmid 1993, Kim et al. 1996, Kim and Kim 1999), and in glycoprotein signaling during the red algal wound-healing process ( Fritz 1993a, Kim et al. 1995). Recently, we reported that some lectins are involved in protoplast formation in vitro of two green algae, Microdyction umbilicatum (Kim et al. 2002) and Chaetomorpha aerea (Klotchkova et al. 2003 ). ...
When the coenocytic green alga Bryopsis plumosa (Huds.) Ag. was cut open and the cell contents were expelled, the cell organelles agglutinated rapidly in seawater to form protoplasts. Aggregation of cell organelles in seawater was mediated by a lectin–carbohydrate complementary system. Two sugars, N-acetyl-d-glucosamine and N-acetyl-d-galactosamine inhibited aggregation of cell organelles. The presence of these sugars on the surface of chloroplasts was verified with their complementary fluorescein isothiacyanate-labeled lectins. An agglutination assay using human erythrocytes showed the presence of lectins specific for N-acetyl-d-galactosamine and N-acetyl-d-glucosamine in the crude extract. One-step column purification using N-acetyl-d-glucosamine-agarose affinity chromatography yielded a homogeneous protein. The protein agglutinated the cell organelles of B. plumosa, and its agglutinating activity was inhibited by the above sugars. Sodium dodecyl sulfate polyacrylamide gel electrophoresis results showed that this protein might be composed of two identical subunits cross-linked by two disulfide bridges. Enzyme and chemical deglycosylation experiments showed that this protein is deficient in glycosylation. The molecular weight was determined as 53.8 kDa by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The N-terminal 15 amino acid sequence of the lectin was Ser–Asp–Leu–Pro–Thr–X–Asp–Phe–Phe–His–Ile–Pro–Glu–Arg–Tyr, and showed no sequence homology to those of other reported proteins. These results suggest that this lectin belongs to a new class of lectins. We named this novel lectin from B. plumosa“bryohealin.”