To analyze the morphological features of the algicidal process, algal cells were collected and observed by scanning electron microscope (SEM). Algal cells (1 mL) were first fixed with glutaraldehyde (2.5%) and washed in phosphate buffered saline (PBS) solution (50 mM, pH 7.8); cells were then placed on cover slips and air-dried. After that, the slides were subjected to SEM (JSM6390, JEOL Co., Tokyo, Japan) analysis after dehydration. To analyze ultrastructural changes, algal cells were observed by a transmission electron microscope (TEM, JEM2100HC, JEOL Co., Tokyo, Japan) according to our previous study (Zhang et al., 2013 (link)).
Changes in nucleus structure were analyzed by confocal laser scanning microscope (CLSM, Zeiss LSM 780, Carl Zeiss, Jena, Germany). Algal cells were fixed with 1% paraformaldehyde, then washed and resuspended in PBS. Cells were then stained with 5 μg/mL 4′,6-diamidino-2-phenylindole (DAPI) for 15 min in the dark. After washing with PBS, algal cells were placed on slides for CLSM observation. DAPI fluorescence was read at 460 nm and represented with blue color on images. Chlorophyll fluorescence was monitored at 680 nm and represented with red color on images.
Changes in nucleus structure were analyzed by confocal laser scanning microscope (CLSM, Zeiss LSM 780, Carl Zeiss, Jena, Germany). Algal cells were fixed with 1% paraformaldehyde, then washed and resuspended in PBS. Cells were then stained with 5 μg/mL 4′,6-diamidino-2-phenylindole (DAPI) for 15 min in the dark. After washing with PBS, algal cells were placed on slides for CLSM observation. DAPI fluorescence was read at 460 nm and represented with blue color on images. Chlorophyll fluorescence was monitored at 680 nm and represented with red color on images.
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