A Ten-Minute Bioassay to Test Metal Toxicity with the Freshwater Flagellate Euglena agilis.

A chemical analysis of water quality cannot detect some toxicants due to time constraints, high costs, and limited interactions for detection. Bioassays would offer a complementary means to assess pollution levels in water. Euglena is a flagellate green alga and an excellent system for toxicity testing thanks to its ease of culture, rapid growth, and quick response to environmental stresses. Herein, we examined the sensitivity of E. agilis to seven heavy metals by analyzing six end-point parameters: motility, velocity, cell compactness, upward swimming, r-value, and alignment. Notably, the velocity of E. agilis was most sensitive to cadmium (96.28 mg·L-1), copper (6.51 mg·L-1), manganese (103.28 mg·L-1), lead (78.04 mg·L-1), and zinc (101.90 mg·L-1), while r-values were most sensitive to arsenic (12.84 mg·L-1) and mercury (4.26 mg·L-1). In this study, velocity and r-values are presented as useful biomarkers for the assessment of metal toxicity in Euglena. The metals As, Cd, Cu, and Pb were suitable for this test. The advantages of the ecotoxicity test are its rapidity: It takes 10 min to obtain results, as opposed to the typical 3-4 d of exposure time with intensive labor. Moreover, this test can be performed at room temperature under dark conditions.

Evaluating features of periphytic diatom communities as biomonitoring tools in fresh, brackish and marine waters.

The aims of this study were to assess the biodiversity of periphytic diatom assemblages in fresh, brackish and marine waterbodies of Korea, and to assess the effect of environmental and anthropogenic factors on parameters such as the quantity and biovolume of lipid bodies and deformations of diatoms as early warning measures of anthropogenic impact. Diatom samples were collected from 31 sites (14 freshwater, 10 brackish and 7 marine), which included less impacted (upstream) and impacted (downstream) sites in each water type. Our results showed higher abundance and biodiversity of periphytic diatoms at the less impacted sites in terms of species richness, Shannon index, cell count and biovolume of the communities than at the impacted sites for freshwater and estuarine sites, but not for marine sites. 84 diatom species were noted in freshwater, 80 in brackish water and 40 in marine waters. In comparison to diatoms of the impacted sites, those of less impacted freshwater, brackish and marine sites had less lipid bodies (also less biovolume) and a lower percentage of teratological frustules, and showed more mobile forms in the community. Principal component analysis (PCA) also showed clear segregation of impacted from less impacted sites by the extent of the presence of lipid bodies (higher both in number and biovolume) and deformities in diatom frustules. Pearson correlation analysis revealed that lipid body induction and deformities were positively correlated with metals (Cd, Co, Cr, Cu, Fe, Pb and Zn) and nutrients (total phosphorus and total nitrogen), whereas they showed negative correlation with salinity, dissolved oxygen, suspended solutes and pH. Life-forms, lipid bodies and deformities in diatoms may be an effective biomonitoring tool for assessing biological effects of pollutants in non-marine aquatic ecosystems in Korea.

Modulation of viability and apoptosis of UVB-exposed human keratinocyte HaCaT cells by aqueous methanol extract of laver (Porphyra yezoensis).

We investigated the effect of 80% methanol extract of laver (Porphyra yezoensis) on the UVB-exposed HaCaT cells, human keratinocytes. The laver extract showed absorbance spectrum characteristic of porphyra-334 or shinorine, major mycosporine-like amino acids (MAAs) in red algae, and contained phenolic compounds. UVB exposure decreased cell viability and increased apoptotic cell fractions, and it also decreased the ratio of reduced (GSH) to oxidized glutathione (GSSG) and the total glutathione content. Post-treatment with the laver extract significantly increased the net viability and also the apoptotic cell fractions of UVB-exposed cells. The extract caused increase in GSH/GSSG ratio, yet it exacerbated the decrease in glutathione content in the UVB-exposed cells. These effects of the laver extract were also manifested in the sham-exposed cells, suggesting that those effects might be general phenomena caused by the laver extract. The extract treatment enhanced the UVB-induced phosphorylation of JNK and ERK, affecting more the latter. Our results suggest that the post-treatment with laver extract may protect UVB-exposed skin cells not only by increasing overall cell proliferation but also by enhancing apoptosis of damaged cells, via activating JNK and ERK signaling pathways, in which modulation of the content and redox status of glutathione may take significant parts.