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The Gonggeom-ji reservoir is an agricultural one built for rice farming during the Proto-Three Kingdoms period and was designated as Gyeongsangbuk-do monument No. 121 because of its high historical value. The Nakdonggang National Institute of Biological Resources has been conducting paleontological and paleoenvironmental studies on major wetlands from Korea since 2016, as well as diatom, geological, and depth distribution analyses on the sedimentary soil of Gonggeom-ji. This study summarized the description and ecological characteristics of six newly recorded diatoms (Gomphonema lacusrankala, Pinnularia diandae, P. gibba var. hyaline, P. lacunarum, Sellaphora labda var. nipponica, Stauroneis angustilancea) found in samples collected through drilling in Gonggeom-ji in 2019. [ABSTRACT FROM AUTHOR]

Globally, cyanobacteria frequently cause blooms that outcompete other species in the waterbody, affecting the diversity, decreasing water exchange rates, and promoting eutrophication that leads to excessive algal growth. Here, Dolichospermum circinale (akinetes) and Microcystic aeruginosa (resting cells), were isolated from the sediment in the Uiam Dam in the North Han River and near Ugok Bridge in the Nakdong River, respectively. The morphology, germination process and rates, and growth was evaluated in different environmental conditions. D. cercinalis germination began on day two of culturing, with maximum cell growth observed on day ten. In contrast, M. aeruginosa exhibited daily increase in cell density and colony size, with notable density increase on day six. Next, different environmental conditions were assessed. Akinetes exhibited high germination rates at low light intensity (5—30 µmol/m2/s), whereas resting cells exhibited high growth rates at high light intensity (50—100 µmol/m2/s). Furthermore, both cell types exhibited optimum germination and growth in media containing N and P at 20—30° at a pH of 7—9. Our study reveals the optimum conditions for the germination and growth of cyanobacterial akinetes and resting cells isolated from river sediment, respectively, and will assist in predicting cyanobacterial blooms for appropriate management. [ABSTRACT FROM AUTHOR]

East Asian summer monsoon (EASM)-driven rapid hydroclimatic variation is a crucial factor with major socioeconomic impacts. Nevertheless, decadal- to centennial-scale EASM variability over the last two millennia is still poorly understood. Pollen-based quantitative annual precipitation (PqPann) and annual precipitation reconstructed by artificial neural networks (ANNs) for the period 650–1940 CE were reconstructed from a paleo-reservoir in South Korea. ANNs reconstruction was performed to compensate for a hiatus section. On a decadal timescale, 10 high-precipitation periods were identified, and PqPann and ANNs reconstructions were comparable to local instrumental rainfall and historic drought records. Biotic lags to rapid climatic changes ranging from 25 to 100 years were recognized by asynchronous pollen and speleothem responses to precipitation. We suggest that PqPann-based decadal- to centennial-scale climatic change reconstruction should take biotic lags into account, although the lags can be ignored on the millennial scale. The position of the EASM rainband influenced rainfall magnitude. [ABSTRACT FROM AUTHOR]

The paleoenvironmental history of the artificial Reservoir Gonggeomji in Sangju City, Korea, was reconstructed using fossil diatom analysis of four sediment cores: GG01, 02, 03, and 04. Accelerator mass spectrometer (AMS) radiocarbon dating results suggest that Reservoir Gonggeomji was maintained from ca. 1350 to 150 cal year BP, and the diatom record in core sediment samples revealed well-defined hydrological changes and paleoenvironmental conditions during this period. The fossil diatom assemblages were predominantly benthic freshwater diatoms. The highest diatom concentrations in all cores were in diatom zone II, in which species richness and diversity were also very high. Cymbella, Eunotia, Gomphonema, Gyrosigma, Navicula, and Pinnularia were the dominant genera in all core sediments. The long-term trend in diatom species abundance and species diversity showed a stronger relationship to temperature anomalies in the northern hemisphere during the past 2000 years with changes in precipitation. These diatom changes could have been controlled by natural climate change, despite anthropogenic activities linked to construction of the dyke in the artificial reservoir. [ABSTRACT FROM AUTHOR]

To predict the clinical usefulness of DA-125, a newly developed doxorubicin analog, we compared its antitumor activity against 20 different human cancer cell lines with that of doxorubicin using the MTT in vitro chemosensitivity test. We also measured and compared the cellular uptake of this drug and doxorubicin in two cancer cell lines and their doxorubicin-resistant sublines. In the MTT test, DA-125 showed lower IC50 values than doxorubicin for 14 of 20 cell lines. DA-125 was more potent than doxorubicin for hepatocellular cancer cells with high mdr 1 expression. Among cancer cells from the stomach and colon, DA-125 was more potent than doxorubicin in 12 of 14 cell lines. We also investigated the cross-resistance of this drug with doxorubicin using four doxorubicin-resistant cancer cell sublines. Except in one cell line, there was very low cross-resistance. Cellular drug-uptake experiments were performed for two gastric cancer cell lines and their doxorubicin-resistant sublines. In this experiment, DA-125 was found to be very rapidly and completely converted to its active metabolite, M1, in the culture media. After this conversion, M1 was incorporated into these cancer cells more rapidly and reached higher intracellular concentrations than doxorubicin, suggesting that DA-125 (as M1) could achieve earlier and higher levels of intracellular accumulation than doxorubicin in its target tissues from the bloodstream. As a possible alternative antineoplastic agent to doxorubicin, DA-125 awaits further evaluation for its antitumor activity and toxicity. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. The authors wish to revise the "Acknowledgements" section of their article. [ABSTRACT FROM AUTHOR]