Hexavalent chromium is cytotoxic and genotoxic to hawksbill sea turtle cells

Abstract

Sea turtles are a charismatic and ancient ocean species and can serve as key indicators for ocean ecosystems, including coral reefs and sea grass beds as well as coastal beaches. Genotoxicity studies in the species are absent, limiting our understanding of the impact of environmental toxicants on sea turtles. Hexavalent chromium (Cr(VI)) is a ubiquitous environmental problem worldwide, and recent studies show it is a global marine pollutant of concern. Thus, we evaluated the cytotoxicity and genotoxicity of soluble and particulate Cr(VI) in hawksbill sea turtle cells. Particulate Cr(VI) was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5 μg/cm2 lead chromate induced 108, 79, 54, and 7 percent relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5 μg/cm2 lead chromate induced damage in 4, 10, 15, 26, and 36 percent of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. For soluble Cr, concentrations of 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate induced 84, 69, 46, 25, and 3 percent relative survival, respectively. Sodium chromate induced 3, 9, 9, 14, 21, and 29 percent of metaphases with damage, and caused 3, 10, 10, 16, 26, and 39 damaged chromosomes in 100 metaphases at concentrations of 0, 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate, respectively. These data suggest that Cr(VI) may be a concern for hawksbill sea turtles and sea turtles in general.

The comparative cytotoxicity and genotoxicity of hexavalent chromium in humans and sea turtles.

“…However, the reason behind this difference is not yet known. The intracellular chromium ion concentrations reported here in leatherback sea turtle cells follows a trend similar to that which was previously reported in hawksbill sea turtle cells [50]. However, the intracellular Cr ion concentrations in hawksbill skin cells was much lower than those reported in this study in leatherback sea turtle cells.…”

“…One other study evaluated Cr(VI) cytotoxicity in sea turtle cells [60]. That study measured the also assessed in the hawksbill sea turtle study which showed a similar trend in response observed in the leatherback sea turtles [50]. However, in the hawksbill sea turtle study there were no metaphases at 5 μM sodium chromate and 5 μg/cm 2 lead chromate whereas in leatherback sea turtles chromosome damage continued to increase.…”

“…All three chromate compounds, soluble sodium chromate, particulate zinc chromate, and particulate lead chromate, induced a concentration dependent increase in cytotoxicity after 24 h exposure. The levels of cytotoxicity caused by Cr(VI) exposure were assessed in a previous study using hawksbill sea turtle skin cells [50]. That study also found that both soluble and particulate Cr(VI) were cytotoxic in hawksbill sea turtles.…”

“…Previously, the Wise Laboratory found Cr(VI) was both cytotoxic and genotoxic to another sea turtle species, the hawksbill sea turtle (Eretmochelys imbricate) [7,50].…”

“…All experiments were maintained in a 37°C, humidified incubator with 5% CO2. [49,50]. During the preparation of the appropriate dilutions and during the treatment procedure the particles were kept in suspension using a vortex mixer.…”