title: Effects of Pb(Ⅱ) exposure on Chlorella protothecoides and Chlorella vulgaris growth, malondialdehyde, and photosynthesis-related gene transcription.
abstract: Greater exposure to Pb(Ⅱ) increases the likelihood of harmful effects in the environment. In this study, the aquatic unicellular alga Chlorella protothecoides (C. protothecoides) and Chlorella vulgaris (C. vulgaris) were chosen to assess the acute and chronic toxicity of Pb(Ⅱ) exposure. Results of the observations show dose-response relationships could be clearly observed between Pb(Ⅱ) concentration and percentage inhibition (PI). Exposure to Pb(Ⅱ) increased malondialdehyde (MDA) content by up to 4.22 times compared with the control, suggesting that there was some oxidative damage. ANOVA analysis shows that Pb(Ⅱ) decreased chlorophyll (chl) content, indicating marked concentration-dependent relationships, and the lowest levels of chl a, chl b, and total-chl were 14.53, 18.80, and 17.95% of the controls, respectively. A real-time PCR assay suggests the changes in transcript abundances of three photosynthetic-related genes. After 120 h exposure Pb(Ⅱ) reduced the transcript abundance of rbcL, psaB, and psbC, and the relative abundances of the three genes of C. protothecoides and C. vulgaris in response to Pb(Ⅱ) were 54.66-98.59, 51.68-95.59, 37.89-95.48, 36.04-94.94, 41.19-91.20, and 58.75-96.80% of those of the controls, respectively. As for 28 d treatments, the three genes displayed similar inhibitory trend. This research provides a basic understanding of Pb(Ⅱ) toxicity to aquatic organisms.
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai, 200237, People's Republic of China; School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China.
authors.forename: Bang
authors.initials: B
authors.lastname: Xiong
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Kuang-Fei
authors.initials: KF
authors.lastname: Lin
authors.forename: Mei-Jin
authors.initials: MJ
authors.lastname: Guo
authors.forename: Wei-Liang
authors.initials: WL
authors.lastname: Wang
authors.forename: Xin-Hong
authors.initials: XH
authors.lastname: Cui
authors.forename: Hua-Song
authors.initials: HS
authors.lastname: Bi
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
mesh_terms: D002708:Chlorella / Q000187:drug effects* / Q000502:physiology; D048408:Chlorella vulgaris / Q000187:drug effects / Q000502:physiology; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000378:metabolism; D000077194:Chlorophyll A; D004785:Environmental Pollutants / Q000633:toxicity*; D007854:Lead / Q000633:toxicity*; D008315:Malondialdehyde / Q000378:metabolism*; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000187:drug effects* / Q000235:genetics; D013045:Species Specificity; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D004785:Environmental Pollutants; D002734:Chlorophyll; C085815:chlorophyll a'; D007854:Lead; C029891:lead chloride; D008315:Malondialdehyde; C037184:chlorophyll b; D000077194:Chlorophyll A
keywords: Chlorella protothecoides; Chlorella vulgaris; Pb(Ⅱ); gene transcription; physiological level