Investigations on the occurrence of lectins in marine sponges with special regard to some species of the family axinellidae

Isolation, biochemical characterization and antibiofilm effect of a lectin from the marine sponge Aplysina lactuca

A new lectin was isolated from the marine sponge Aplysina lactuca (ALL) by combining ammonium sulfate precipitation and affinity chromatography on guar gum matrix. ALL showed affinity for the disaccharides α-lactose, β-lactose and lactulose (Ka=12.5, 31.9 and 145.5M^-1, respectively), as well as the glycoprotein porcine stomach mucin. Its hemagglutinating activity was stable in neutral acid pH values and temperatures below 60°C. ALL is a dimeric protein formed by two covalently linked polypeptide chains. The average molecular mass, as determined by Electrospray Ionization Mass Spectrometry (ESI-MS), was 31,810±2Da. ESI-MS data also indicated the presence of three cysteines involved in one intrachain and one interchain disulfide bond. The partial amino acid sequence of ALL was determined by tandem mass spectrometry. Eight tryptic peptides presented similarity with lectin I isolated from Axinella polypoides. Its secondary structure is predominantly β-sheet, as indicated by circular dichroism (CD) spectroscopy. ALL agglutinated gram-positive and gram-negative bacterial cells, and it were able to significantly reduce the biomass of the bacterial biofilm tested at dose- dependent effect.

Porifera Lectins: Diversity, Physiological Roles and Biotechnological Potential

An overview on the diversity of 39 lectins from the phylum Porifera is presented, including 38 lectins, which were identified from the class of demosponges, and one lectin from the class of hexactinellida. Their purification from crude extracts was mainly performed by using affinity chromatography and gel filtration techniques. Other protocols were also developed in order to collect and study sponge lectins, including screening of sponge genomes and expression in heterologous bacterial systems. The characterization of the lectins was performed by Edman degradation or mass spectrometry. Regarding their physiological roles, sponge lectins showed to be involved in morphogenesis and cell interaction, biomineralization and spiculogenesis, as well as host defense mechanisms and potentially in the association between the sponge and its microorganisms. In addition, these lectins exhibited a broad range of bioactivities, including modulation of inflammatory response, antimicrobial and cytotoxic activities, as well as anticancer and neuromodulatory activity. In view of their potential pharmacological applications, sponge lectins constitute promising molecules of biotechnological interest.

A lactose-binding lectin from the marine sponge Cinachyrella apion (Cal) induces cell death in human cervical adenocarcinoma cells

Cancer represents a set of more than 100 diseases, including malignant tumors from different locations. Strategies inducing differentiation have had limited success in the treatment of established cancers. Marine sponges are a biological reservoir of bioactive molecules, especially lectins. Several animal and plant lectins were purified with antitumor activity, mitogenic, anti-inflammatory and antiviral, but there are few reports in the literature describing the mechanism of action of lectins purified from marine sponges to induce apoptosis in human tumor cells. In this work, a lectin purified from the marine sponge Cinachyrella apion (CaL) was evaluated with respect to its hemolytic, cytotoxic and antiproliferative properties, besides the ability to induce cell death in tumor cells. The antiproliferative activity of CaL was tested against HeLa, PC3 and 3T3 cell lines, with highest growth inhibition for HeLa, reducing cell growth at a dose dependent manner (0.5–10 µg/mL). Hemolytic activity and toxicity against peripheral blood cells were tested using the concentration of IC₅₀ (10 µg/mL) for both trials and twice the IC₅₀ for analysis in flow cytometry, indicating that CaL is not toxic to these cells. To assess the mechanism of cell death caused by CaL in HeLa cells, we performed flow cytometry and western blotting. Results showed that lectin probably induces cell death by apoptosis activation by pro-apoptotic protein Bax, promoting mitochondrial membrane permeabilization, cell cycle arrest in S phase and acting as both dependent and/or independent of caspases pathway. These results indicate the potential of CaL in studies of medicine for treating cancer.

Biological activities of ACL-I and physicochemical properties of ACL-II, lectins isolated from the marine sponge Axinella corrugata

Lectin II from the marine sponge Axinella corrugata (ACL-II) was purified by affinity chromatography on rabbit erythrocytic stroma incorporated into a polyacrylamide gel, followed by gel filtration on Ultrogel AcA 44 column. Purified ACL-II is a lectin with an Mr of 80 kDa and 78 kDa, estimated by SDS-PAGE and by FPLC on Superose 12 HR column, respectively. ACL-II mainly agglutinates native rabbit erythrocytes and this hemagglutinating activity is independent of Ca(2+), Mg(2+) and Mn(2+), but is inhibited by d-galactose, chitin and N-acetyl derivatives, with the exception of GalNAc. ACL-II is stable for up to 65 °C for 30 min, with a better stability at a pH range of 2 to 6. In contrast, ACL-I displays a strong mitogenic and cytotoxic effect.

Immunohistochemical localization of an N-acetyl amino-carbohydrate specific lectin (ACL-I) of the marine sponge Axinella corrugata

The N-acetyl amino-carbohydrate specific lectin (ACL-I) was previously identified and purified by us from the marine sponge Axinella corrugata (phylum Porifera, class Demospongiae). The distribution of the specific lectin within the tissue of the sponge was studied by bright-field optical microscopy immunohistochemistry in order to better understand its physiological role in the sponge. Polyclonal antibodies were raised against purified ACL-I in mice and tested by Western blot technique. The immunohistochemical analysis of ACL-I in cross sections of A. corrugata showed that this lectin is found inside the denominated spherulous cells, which contain vesicles that store the lectin. Some evidence is shown that ACL-I might also be present in the extracellular matrix. It was not possible to demonstrate by the immunohistochemical technique if ACL-I is colocalized in both the plasma membrane and in the cytoplasm of the spherulous cells.

Marine glycobiology: current status and future perspectives

Glycobiology, which is the study of the structure and function of carbohydrates and carbohydrate containing molecules, is fundamental to all biological systems.Progress in glycobiology has shed light on a range of complex biological processes associated with, for example,disease and immunology, molecular and cellular communication,and developmental biology. There is an established,if rather modest, tradition of glycobiology research in marine systems that has primarily focused on reproduction,biofouling, and chemical communication. The current status of marine glycobiology research is primarily descriptive with very limited progress on structural elucidation and the subsequent definition of precise functional roles beyond a small number of classical examples, e.g., induction of the acrosome reaction in echinoderms. However, with recent advances in analytical instrumentation, there is now the capacity to begin to characterize marine glycoconjugates,many of which will have potential biomedical and biotechnological applications. The analytical approach to glycoscience has developed to such an extent that it has acquired its own "-omics" identity. Glycomics is the quest to decipher the complex information conveyed by carbohydrate molecules--the carbohydrate code or glycocode. Due to the paucity of structural information available, this article will highlight the fundamental importance of glycobiology for many biological processes in marine organisms and will draw upon the best defined systems. These systems therefore may prove genuine candidates for full carbohydrate characterization.

A lactose specific lectin from the sponge Cinachyrella apion: purification, characterization, N-terminal sequences alignment and agglutinating activity on Leishmania promastigotes

Crude extract from the sponge Cinachyrella apion showed cross-reactivity with the polyclonal antibody IgG anti-CvL (Cliona varians lectin) and also a strong haemagglutinating activity towards human erythrocytes of all ABO groups. Thus, it was submitted to acetone fractionation, IgG anti-deglycosylated CvL Sepharose affinity chromatography, and Fast Protein Liquid Chromatography (FPLC-AKTA Purifier) gel filtration on a Superose 6 10/300 column to purify a novel lectin. C. apion lectin (CaL) agglutinated all types of human erythrocytes with preference for papainized type A erythrocytes. The haemagglutinating activity is independent of Ca2+, Mg2+ and Mn2+ ions, and it was strongly inhibited by the disaccharide lactose, up to a minimum concentration of 6.25 mM. CaL molecular mass, determined by FPLC-gel filtration on a Superose 12 10/300 column and SDS gel electrophoresis, was approximately 124 kDa, consisting of eight subunits of 15.5 kDa, assembled by hydrophobic interactions. The lectin was heat-stable between 0 and 60 degrees C and pH-stable. The N-terminal amino acid sequence of CaL was also determined and a blast search on amino acid sequences revealed that the protein showed similarity only with a silicatein. Leishmania chagasi promastigotes were agglutinated by CaL and this activity was abolished by lactose, indicating that lactose receptors could be presented in this parasite stage. These findings are indicative of the potential biotechnological application of CaL as diagnostic of pathogenic protozoa.

ACL-I, a lectin from the marine sponge Axinella corrugata: isolation, characterization and chemotactic activity

The lectin from the marine sponge Axinella corrugata (ACL-I) was purified by affinity chromatography on rabbit erythrocytic stroma incorporated into a polyacrylamide gel followed by gel filtration on Ultrogel AcA 44 column. Purified ACL-I is a hexameric glycoprotein with a Mr of 82.3 kDa estimated by SDS-PAGE and 78.5 kDa by FPLC on Superose 12 HR column. The pI of lectin is 6.3 and ACL-I is constituted of 13.9 kDa similar subunits some of them linked by disulphide bridges. This lectin agglutinates native rabbit, goat and dog erythrocytes and in less extent human erythrocytes. The hemagglutinating activity is independent of Ca(2+), Mg(2+) and Mn(2+), but it is strongly inhibited by carbohydrates containing N-acetyl groups. ACL-I is stable up to 70 degrees C for 30 min, with optimum pH between 7 and 8, and it is also resistant to enzymatic proteolysis in vitro. In the presence of reducing or denaturant agents, the lectin activity decreases. ACL-I displays chemotactic effect on rat neutrophil in vitro which is inhibited by N-acetyl-d-glucosamine.

Production of the cytostatic agent aeroplysinin by the sponge Verongia aerophoba in in vitro culture

1. The marine sponge Verongia aerophoba contains two bioactive secondary metabolites from tyrosine, (+)-aeroplysinin-1 [3',5'-dibromo-1',2'-dihydroxy-4'- methoxycyclohexa-3',5'-dien-1'-yl-methyl-cyanide; abbreviated AP] and dibromoverongia-quinol [3',5'-dibromo-1'-hydroxy- 4'-oxocyclohexa-2',5'-dien-1'-yl-acetamide; abbreviated DV], which display strong cytostatic activity. 2. The concentrations causing 50% inhibition of cell growth are 0.47 microM (AP) and 1.21 microM (DV), resp. 3. Depending on depth regions from which the sponges were collected, differences in occurrence of metabolites were observed. 4. AP and DV were found to be present in sponges collected at a depth of 5-10 m, whereas only DV could be detected in material from deeper regions (20-30 m). 5. AP is present only in the surface layers (both the outer and oscular region) of the sponge, while in the centre of the sponge only DV is detected. 6. Cubes from sponges, collected at a depth of 30 m, were cultivated in seawater in vitro and were found to have the capacity (i) to synthesize AP, and (ii) to release this bioactive material into the medium under defined conditions. Under optimal conditions (light and aeration) 100 g of sponge synthesize and release 13.02 mg of AP during a 10-day incubation period. 7. In the dark and without aeration this synthesis was prevented. 8. These data show that also under in vitro conditions sponges retain the capability of producing bioactive compounds and can be induced to produce even substances which they did not secrete in their natural environment.