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Determination and Occurrence of Retinoids in a Eutrophic Lake (Taihu Lake, China): Cyanobacteria Blooms Produce Teratogenic Retinal

Wu, Xiaoqin, Jiang, Jieqiong, Hu, Jianying
Environmental Science & Technology 2013 v.47 no.2 pp. 807-814
Chlamydomonas, Microcystis, algae, analytical methods, aquatic animals, beta-carotene, biochemical pathways, developmental stages, eutrophication, lakes, retinoic acid, retinyl palmitate, risk, surface water, teratogenicity, vertebrates, vitamin A, China
Besides retinoic acids (RAs), some retinoids such as retinal (RAL) and retinol (ROH), which are considered as RA precursors in vertebrates, are also reported to be teratogenic agents. In this study we investigated four RA precursors including RAL, ROH, retinyl palmitate, and β-carotene in the eutrophic Taihu Lake, China, by developing a sensitive analytical method. RAL and β-carotene were widely detected in natural cyanobacteria blooms and lake water. Intracellular concentrations of RAL and β-carotene in blooms were 9.4 to 6.9 × 10³ and 3.4 to 1.8 × 10⁵ ng L–¹, respectively, and their concentrations in lake water were up to 1.4 × 10 ng L–¹ (RAL) and 9.8 × 10² ng L–¹ (β-carotene). The good correlation between intracellular concentrations of RAL and RAs implied that RAL was involved in the production of RAs by cyanobacteria blooms. Further examination of 39 cyanobacteria and algae species revealed that most species could produce RAL and β-carotene. The greatest amount of RAL was found in Chlamydomonas sp. (FACHB-715; 1.9 × 10³ ng g–¹ dry weight). As the main cyanobacteria in Taihu Lake, many Microcystis species could produce high amounts of RAL and were thought to greatly contribute to the production of RAL measured in the blooms. Productions of RAL and β-carotene by cyanobacteria were associated with species, origin location, and growth stage. The results in this study present the existence of a potential risk to aquatic animals living in a eutrophic environment from a high concentration of RAL in cyanobacteria blooms and also provide a clue for further investigating the mechanism underlying the biosynthetic pathway of RAs in cyanobacteria and algae.