TY - JOUR
T1 - Effects of lead on two green microalgae Chlorella and Scenedesmus: photosystem II activity and heterogeneity
AU - Dao, Ly H T
AU - Beardall, John
PY - 2016
Y1 - 2016
N2 - Lead is a toxic, non-essential, heavy metal which affects photosynthesis by interacting with the essential metals integrated in photosynthetic apparatus or in metalloenzymes necessary for photosynthesis. However, studies of its effect on algal photophysiology, including the functional organization of PSII, are scarce. In this study, we used various non-invasive chlorophyll fluorescence measurements to investigate the changes in structural and functional aspects of the photosynthetic apparatus in two freshwater green algae, Chlorella and Scenedesmus, brought about under lead toxicity. PSII performance was inhibited by lead, as indicated by the decrease in maximum quantum yield and performance index. Flash fluorescence induction curves revealed that there was a significant alteration in antenna heterogeneity in which the decrease of PSII energetic connectivity (Joliot's p, Strasser's p2G, Paillotin's Ω, Lavergne's J) and the increase of antenna size under lead was remarkable. QA reoxidation and OJIP-derived parameters showed an increase in QB non-reducing reaction centres in Chlorella, but not in Scenedesmus, when grown in the presence of lead. Analysis of QA-reoxidation in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) providing data about O2-evolving/non-O2 evolving RCs, also showed the increase of inactive RCs under lead treatment in Chlorella but not in Scenedesmus. In addition, from the heterogeneity measurement results, differences between QB reducing vs PSIIα and QB non-reducing vs PSIIβ could clearly be distinguished.
AB - Lead is a toxic, non-essential, heavy metal which affects photosynthesis by interacting with the essential metals integrated in photosynthetic apparatus or in metalloenzymes necessary for photosynthesis. However, studies of its effect on algal photophysiology, including the functional organization of PSII, are scarce. In this study, we used various non-invasive chlorophyll fluorescence measurements to investigate the changes in structural and functional aspects of the photosynthetic apparatus in two freshwater green algae, Chlorella and Scenedesmus, brought about under lead toxicity. PSII performance was inhibited by lead, as indicated by the decrease in maximum quantum yield and performance index. Flash fluorescence induction curves revealed that there was a significant alteration in antenna heterogeneity in which the decrease of PSII energetic connectivity (Joliot's p, Strasser's p2G, Paillotin's Ω, Lavergne's J) and the increase of antenna size under lead was remarkable. QA reoxidation and OJIP-derived parameters showed an increase in QB non-reducing reaction centres in Chlorella, but not in Scenedesmus, when grown in the presence of lead. Analysis of QA-reoxidation in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) providing data about O2-evolving/non-O2 evolving RCs, also showed the increase of inactive RCs under lead treatment in Chlorella but not in Scenedesmus. In addition, from the heterogeneity measurement results, differences between QB reducing vs PSIIα and QB non-reducing vs PSIIβ could clearly be distinguished.
KW - Algae
KW - Chlorophyll a fluorescence
KW - Lead
KW - Photosynthesis
KW - PSII heterogeneity
UR - http://www.sciencedirect.com.ezproxy.lib.monash.edu.au/science/article/pii/S2211926416300789/pdfft?md5=e216fb711d1135a442dd4d7be7fbce93&pid=1-s2.0-S22
U2 - 10.1016/j.algal.2016.03.006
DO - 10.1016/j.algal.2016.03.006
M3 - Article
SN - 2211-9264
VL - 16
SP - 150
EP - 159
JO - Algal Research
JF - Algal Research
ER -