Subcellular localization of a lectin in Bryopsis hypnoides (Bryopsidales, Chlorophyceae) and its expression during cell organellar aggregation

Abstract

Xu M., Lü F., Peng G., Niu J. and Wang G. 2012. Subcellular localization of a lectin in Bryopsis hypnoides (Bryopsidales, Chlorophyceae) and its expression during cell organellar aggregation. Phycologia 51: 340–346. DOI: 10.2216/10-37.1The protoplasm of giant-celled Bryopsis species is totipotent. When protoplasm is extruded from the fresh alga into seawater, the organelles – including protoplasts, nucleus and other cell contents – can aggregate and reconstitute a whole cell, even regenerate into a mature individual. It is believed that a lectin–carbohydrate complementary system is involved in these surprising processes. To address this issue, a polyclonal antibody against the lectin in Bryopsis hypnoides was prepared and used to evaluate the lectin's role in organellar agglutination. Results showed that the agglutination of cell organelles was blocked completely by the antibody. Real-time quantitative polymerase chain reaction of this lectin gene (EU410470.1) demonstrated that it was down-regulated, with expression reaching the lowest level at 6 h and returning to maximal level at 12 h after protoplasm release. Western blotting revealed that a 43-kDa protein appeared at 3 h after protoplasm release, and then disappeared at 6 h. Immunogold localization indicated that the lectin was located in both chloroplast and cytoplasm. These results indicate that lectin plays an indispensable role in agglutination of the cell organelles and the regeneration of this giant-celled alga.