Fourteen FITC-conjugated lectins as a tool for the recognition and differentiation of some harmful algae in Chinese coastal waters

In order to test the use of lectins as a tool for the differentiation of harmful algal species, 13 species and 23 strains of algae were tested with 14 fluorescein isothiocyanate (FITC)-conjugated lectins, and the results examined using flow cytometry (FCM), epifluorescence microscopy (EFM) and spectrofluorometry (SFM). The lectin probes SBA, WGA, GSL I, DBA and PHA-E could distinguish between morphologically similar Gymnodinium -like species, such as Karenia mikimotoi (GMDH01), Takayama pulchellum (TPXM01) and Gymnodinium sp. (GspXM01), by their different binding activities. With the precise quantitative measurements of binding obtained using SFM and FCM, lectins appeared to be useful in distinguishing different strains of the same species. The results also showed that PHA-E could differentiate Alexandrium tamarense (ATDH04) from other strains of this species, and SJA could distinguish A. tamarense (ATMJ02) from other strains of this species (including ATMJ01). Similarly, PNA could identify A. tamarense (ATDH01, 02, 03); UEA I could recognize A. tamarense (ATCI01-JN, ATCI01); and RCA120 could differentiate Alexandrium sp (AspGX01) from strain AspGX02, which was shown to produce different levels of paralytic shellfish poisoning toxin. Lectin probes could also bind these target cells in mixed algal samples. Positive cells identified by FCM were clearer than negative cells thus, in EFM, both GspXM01 and TPXM01 labeled with a WGA lectin probe could be distinguished from target cells of K. mikimotoi , Prorocentrum donghaiense and P. minimum (PMDH01, PMXM01) in mixed algal samples. FCM, EFM and SFM analysis could clearly distinguish lectin-probe-bound cells from negative cells in culture.