portable chlorophyll fluorometer  (Hansatech Instruments)

Journal: Plant Physiology

Article Title: Deciphering the metabolic details of L-lysine toxicity in cyanobacteria

doi: 10.1093/plphys/kiag106

Figure Lengend Snippet: Physiological characterization of Synechocystis under Lys treatment with and without 25 µm Lys. a) Growth represented by the mean of OD 750 ± SD from biological triplicates. b) Photosynthetic efficiency in form of PSII quantum yield ± SD from biological triplicates measured by a PAM fluorometer. c) The whole-cell spectrum of 1 replicate is shown at time points 0 (solid lines) and 96 h (dotted lines) of Lys treatment. Absorbance values are normalized to OD 1.0 at 750 nm. Absorption peaks characteristic of phycobilisomes and chlorophyll a are indicated. d) Representative of DiBAC 4 (3) staining of cells after 48 h of Lys treatment. Green stained cells are dead cells. Some enlarged cells are indicated with red arrows. e) Quantification of average dead cells (in percentage) stained with DiBAC 4 (3) from untreated and Lys-treated biological triplicates. About 500 to 1,000 cells were counted per replicate. Error bars represent the SD of the averages of each replicate. f) Quantification of average cell diameter from about 1,000 cells in total per condition. Bar and whisker denote 5th, 25th, median, 75th, and 95th percentiles. The average diameter of each replicate from biological triplicates was calculated and significance was tested with a Student t -test. Significance is indicated by an asterisk (* = P -value < 0.05). g) Levels of ROS in Lys-treated cells relative to untreated cells (at time point zero) measured from biological triplicates. The error bars represent the propagated relative uncertainty (%). The presence of ROS was quantified using the H2DCFDA fluorescent marker .

Article Snippet: The PSII activity was measured with a WATER-PAM chlorophyll fluorometer (Walz GmbH; Effeltrich, Germany), as described previously ( ).

Techniques: Staining, Whisker Assay, Marker