Physiological and cytological responses of the marine diatom Skeletonema costatum to 2,4-dichlorophenol

• Published in: Aquatic toxicology Vol. 60; no. 1; pp. 33 - 41
• Main Authors: Yang, Shao, Wu, Rudolf S.S., Kong, Richard Y.C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.10.2002; Elsevier Science
• Subjects: 2,4-Dichlorophenol; Adaptation, Physiological; Adenosine Triphosphate - analysis; Animal, plant and microbial ecology; Anthelmintics - adverse effects; Applied ecology; Biological and medical sciences; Chlorophenols - adverse effects; Diatom; Diatoms - physiology; DNA - analysis; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Energy charge; Energy Metabolism - drug effects; Energy reserve; Fundamental and applied biological sciences. Psychology; Marine; Photosynthesis - drug effects; Pigment; Population Dynamics; Protein Biosynthesis; RNA - analysis; Skeletonema costatum; Water Pollutants, Chemical - adverse effects; Pigment; Diatom; 2,4-Dichlorophenol; Energy reserve; Energy charge; Chlorophyll; Growth inhibitor; Population growth; Toxicity; Algae; Cytology; Lipids; Skeletonema costatum; Marine environment; Heterokontophyta; Bacillariophyta; Phytoplankton; Water pollution; Carbohydrate; Physiology; Protein content; Thallophyta; Metabolic storage
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/S0166-445X(01)00258-2

Physiological and cytological responses of the marine diatom, Skeletonema costatum, to 2,4-dichlorophenol (2,4-DCP) were investigated after exposing algal cultures to 1–6 mg l −1 of 2,4-DCP for 96 h. Growth rate of the diatom was significantly reduced by 2,4-DCP at and above 3.0 mg l −1 while other biological parameters such as photosynthetic and respiration rates, carotenoid and protein content, ATP level and adenylate energy charge were unaffected. Exposure to 6.0 mg l −1 2,4-DCP for 96 h resulted in the total lipid content being increased to 304%, while the RNA/DNA ratio was reduced to 31% of the control values. A parallel study by transmission electron microscopy further confirmed the increase in cellular lipid content, as evidenced by the accumulation of lipid droplets within diatom cells. A slight increase in carbohydrate (+37.8%) and decrease in chlorophyll a (−20.4%) and total chlorophyll c (−14.4%) were also found at 6.0 mg l −1 2,4-DCP. Although 2,4-DCP is known to uncouple oxidative phosphorylation, our results show that energy production was not significantly inhibited at sublethal concentrations of 2,4-DCP. The observed growth inhibition in S. costatum caused by 2,4-DCP was associated with an increase in energy storage and inhibition of protein synthesis, as indicated by a reduction in RNA/DNA ratio.