Evaluation of algal species distributions and prediction of cyanophyte cell counts using statistical techniques

Safe drinking water sources are crucial for human health. Consequently, water quality management, including continuous monitoring of water quality and algae at sources, is critical to ensure the availability of safe water for local residents. This study aimed to construct statistical prediction models considering probability distributions relevant to cyanophyte cell counts and compare their prediction performance. In this study, water quality parameters at Juam Lake and Tamjin Lake, representative water sources in the Yeongsan and Seomjin rivers, South Korea, were investigated. We used a water quality monitoring network, algae alert system, and hydraulic and hydrological data measured every 7 days from January 2017 to December 2022 from the Water Environment Information System of the National Institute of Environmental Research. Using data for 2017-2021 as a training set and data for 2022 as a test set, the performances of seven models were compared for predicting cyanophyte cell counts. Environmental factors associated with algae in water sources were observed based on the monitoring data, and a prediction model appropriate for the cyanophyte distribution was generated, which also included the risk of toxicity. The extreme gradient boosting with the random forest model had the best predictive performance for cyanophyte cell counts. The study results are expected to facilitate water quality management in various water systems, including water sources.

Water quality trend and pollutant load and source analysis of Tamjin River water system

To systematically manage water quality based on watersheds, it is necessary to understand the characteristics of changes in river water quality. This study used observational data of the Tamjin River water system to analyze changes in water quality due to farming activities during the farming period. Water quality trends were analyzed through a long-term trend analysis. Furthermore, the loads and sources of substances regulated under the total maximum daily load system were evaluated. Biochemical oxygen demand and total phosphorous, water quality factors of the target basin, showed recent increasing trends. Loads increased from April, which corresponded to the non-farming period before farming activities began, and characteristics of pollutant discharged in the basin from farming activities were observed. Pollutant sources were different from those observed in water systems with a high proportion of farming activities, and water quality management measures considering the target basin's characteristics were proposed. The results of this study will serve as logical baseline data for establishing water quality management plans.

Depletion of intracellular zinc and copper with TPEN results in apoptosis of cultured human retinal pigment epithelial cells

PURPOSE

Although zinc deficiency may contribute to the pathogenesis of age-related macular degeneration, how it leads to retinal pigment epithelium (RPE) degeneration is unknown. To investigate this, cultured human RPE cells were rendered zinc depleted with a membrane-permeant metal chelator, N,N,N',N-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN), and the resultant cytopathic changes were examined.

METHODS

RPE cell degeneration was examined with light microscopy, TdT-mediated dUTP nick end labeling (TUNEL) staining, Hoechst dye staining, and electron microscopy and quantified with cell counting or lactate dehydrogenase release assay. The effect of sublethal zinc depletion on the vulnerability of RPE cells to UV irradiation or hydrogen peroxide (H(2)O(2)) exposure, was studied in cultures without or with pretreatment with low-concentration TPEN.

RESULTS

Exposure to 1 to 4 microM TPEN for 48 hours induced RPE cell death in a concentration-dependent manner. Features of apoptosis such as membrane blebbing, chromatin condensation, nuclear fragmentation, and caspase-3 activation, accompanied the TPEN-induced cell death. Addition of equimolar zinc or copper completely reversed TPEN-induced apoptosis, whereas addition of iron had no effect. As in apoptosis of several other cell types including neurons, a protein synthesis inhibitor as well as caspase inhibitors blocked TPEN-induced apoptosis. On the contrary, at sublethal concentrations, TPEN increased the vulnerability of RPE cells to subsequent UV irradiation but not to H(2)O(2) exposure.

CONCLUSIONS

The present results suggest that depletion of intracellular zinc and copper, but not copper alone, may be harmful to RPE cells, directly inducing apoptosis or indirectly increasing vulnerability of RPE cells to UV injury. The present culture model may be useful for gaining insights into the mechanisms of zinc depletion-associated RPE cell degeneration.