Phenanthrene Accumulation Kinetics in Marine Diatoms

Abstract

Cell surface and intracellular accumulation kinetics of phenanthrene were studied in two coastal marine diatoms. Cell surface uptake and depuration rate constants were two to three times greater in the smaller Thalassiosira pseudonana than in T. weissflogii, reflecting the 2.8-fold difference in surface-area-to-volume ratio (A/V) between the two species. However, cell surface accumulation was faster than most other environmental and biological process, supporting the assumption that cell surfaces are in equilibrium with the water. Intracellular depuration rate constants of phenanthrene were similar (0.56 d(-1), 0.62 d(-1)) for both diatoms and for other hydrophobic organic contaminants (ca 1 d(-1)) with a range of hydrophobicities and chemical structures in other microalgae. Biodilution could be a significant factor in the internal accumulation of phenanthrene, as phenanthrene loss rate constants were on the order of phytoplankton growth rates in the spring and summer (1-3 d(-1)). Organic carbon-normalized phenanthrene bioconcentration factors were not significantly different for the two diatom species. The fraction of phenanthrene in the cell surface compartment at steady-state (x1) was directly related to the A/V of the two diatoms and a Chlorophyte microalga, showing that intracellular partitioning, which may affect phenanthrene trophic transfer, depends on phytoplankton cell size.

Gene regulation in the marine diatom Thalassiosira pseudonana upon exposure to polycyclic aromatic hydrocarbons (PAHs)

“…The observed lower sensitivity might be explained by the low culture temperature, which leads to a reduced uptake or decelerated metabolism (Fan and Reinfelder, 2003). On the other hand, uptake into T. pseudonana is reported to be rather quick, due to its small size and therefore high surface area to volume ratio (Wang and Wang, 2006;Fan and Reinfelder, 2003). A major factor was probably also the ratio of light to dark periods during exposure.…”

Potential effects of sediment contaminants on diatom assemblages in coastal lagoons of New Jersey and New York States

“…Diatoms are also known to be sensitive to toxic substances, such as metals (Cattaneo et al, 2008, Duong et al, 2008Morin et al, 2012) and organic contaminants (Moisset et al, 2015). Classic toxicological approaches, such as testing the effects of contaminants on single species or monoclonal cultures in the laboratory conditions demonstrated effects of individual contaminants and of their mixtures on both freshwater (e.g., Adams and Stauber, 2004;Araujo et al, 2010;Larras et al, 2012,) and marine (e.g., Fan and Reinfelder, 2003;Hagenbuch and Pinkney, 2012;Joux-Arab et al, 2000;Moreno-Garrido et al, 2003, 2007 diatoms. While the traditional tests typically measured growth or survival rates of various species depending on the dosage and length of the exposure to contaminants, a number of recent studies attempted to investigate mechanisms of toxicity by estimating gene expression (Kim Tiam et al, 2012;Moisset et al, 2015) and enzyme activities indicating which cell functions are affected Crespo et al, 2013).…”

PAHs reduce DNA synthesis and delay cell division in the widespread primary producer Prochlorococcus

“…The higher Prochlorococcus sensitivity to pollutants has been explained as a consequence of their small cell volume (Echeveste et al, 2010a). The increase in the surfacevolume ratio as cell size decrease is the primary factor identified as to control the sorption grade of the organic pollutants in the cell surface (Skoglund et al, 1996;Del Vento and Dachs, 2002;Fan and Reinfelder, 2003). As a consequence, the smaller cells have higher capability to incorporate these contaminants into their cells (Del Vento and Dachs, 2002;Echeveste et al, 2010a), and are thus, more sensitive.…”