https://repository.kopri.re.kr/handle/201206/15866 2026-04-09T08:47:00Z 2026-04-09T08:47:00Z Ahn, Yong-Yoon Quoc Anh Nguyen Andrea Spolaor Sefano Frassati Elena Barbaro Giulio Cozzi Clara Turetta Hoon Oh Jaesang Lee Kim, Kitae https://repository.kopri.re.kr/handle/201206/16572 2026-02-09T07:08:50Z 2025-10-01T00:00:00Z

Title: Bromide oxidation by bromate in a frozen solution and reactive bromine species production Authors: Ahn, Yong-Yoon; Quoc Anh Nguyen; Andrea Spolaor; Sefano Frassati; Elena Barbaro; Giulio Cozzi; Clara Turetta; Hoon Oh; Jaesang Lee; Kim, Kitae Abstract: A sudden increase in tropospheric reactive bromine species (such as BrO radical) concentration has been observed in the Arctic springtime (bromine explosion). The reactive bromine radicals originate from the Br2 oxidation; however, the role of ice chemistry in bromine activation, especially freezing-induced Br- oxidation for Br2 production, is not significantly considered yet. Notably, the freezing phenomenon is prevalent in polar region. In this study, we demonstrate that the Br- containing water freezing can provide a potential Br- oxidation pathway. The oxidation of Br- by BrO3- was negligible under aqueous conditions, while it was highly accelerated (time scale of several years to minute) by freezing the solution. We proposed that the accelerated chemical reaction was due to the freezing concentration effect. The chemical transformation mechanism was suggested. The chemical transformation of Br- was considered using the UV-visible absorbance spectrometer and the high-resolution mass spectroscopy (HRMS) measurement. The total Br content was measured using inductive coupled plasma mass spectroscopy (ICP-MS) and the dissolved Br species was monitored using ion chromatography. The spatial distribution of in-situ generated hypobromous acid in ice was analyzed using the Raman microscopy. The Br- oxidation is increased as the decrease of initial pH and increase of reactant dose, but the influence of freezing temperature was not significant. This study provides experimental evidence for the freezing-induced bromide activation in the ice.

2025-10-01T00:00:00Z Sulaiman, Syahril Lee, Hyodong Min, Kyungwon Lee, Jungeun Yoon, Young-Jun Lee, Jun Hyuck Lee, Hyoungseok https://repository.kopri.re.kr/handle/201206/16017 2025-10-29T04:41:55Z 2025-07-01T00:00:00Z

Title: The complete plastome of the Antarctic moss Andreaea regularis (Andreaeaceae) and its comparative analyses within Bryophyta Authors: Sulaiman, Syahril; Lee, Hyodong; Min, Kyungwon; Lee, Jungeun; Yoon, Young-Jun; Lee, Jun Hyuck; Lee, Hyoungseok Abstract: Background Andreaeopsida represents a distinct group of nonperistomate mosses, characterized by its phylogenetic position as a sister to peristomate species. However, plastome data for this lineage remains scarce, limiting our understanding of its genomic features and the evolution of plastome within Bryophyta. To bridge this gap, we sequenced the plastome of Andreaea regularis, a prominent species within the Andreaeopsida, found in Antarctica. This study aims to characterize the plastome of A. regularis and compare its features across nonperistomate and peristomate moss lineages, focusing on phylogenetic placement, plastome characteristics variations, and potential selection pressures. Results The assembled plastome of A. regularis spans 135,217 bp with 30.3% GC content and 122 annotated genes. Phylogenetic analysis confirms the position of A. regularis among the nonperistomate mosses, forming a sister group to the peristomate lineage. Comparative analysis reveals a reduction pattern in plastome size, GC content, and protein-coding gene (PCG) content along the evolutionary trajectory from nonperistomate mosses to peristomate mosses, with A. regularis exhibiting intermediate characteristics. This pattern is mirrored by structural variation in the large single-copy (LSC) region, where A. regularis retains more PCGs and exhibits lower deletion rates than peristomate species but shows signs of genome contraction relative to nonperistomate mosses. Correlation analysis further indicates that total plastome size and GC content are most strongly associated with LSC length (r = 0.994) and GC content (r = 0.999), respectively, suggesting that LSC variation is closely linked to plastome structural differences among mosses. Purifying selection is prevalent across genic regions in mosses, while codon usage patterns remain minimally affected by mutational pressure. The genes rpoC2 and ndhF exhibit dynamic evolution, marked by elevated nonsynonymous substitution rates, high nucleotide diversity, and numerous diagnostic sites. Additionally, positively selected residues in these genes, alongside those in rbcL, indicate potential evolutionary pressures in A. regularis. Conclusions Altogether, this study establishes a critical genomic reference for Andreaeopsida, advances our understanding of nonperistomate-peristomate plastome evolution, and highlights the intricate nucleotide variation underlying plastome diversity and evolutionary differentiation in mosses.

2025-07-01T00:00:00Z Min, Kyungwon Syahril Sulaiman Lee, Jungeun Bravo Leon A. Saez Patricia L. Lee, Hyoungseok https://repository.kopri.re.kr/handle/201206/16128 2025-10-15T00:01:19Z 2025-05-01T00:00:00Z

Title: Transcriptomic responses of Antarctic plants to in situ warming: uncovering molecular mechanisms behind physiological adjustments Authors: Min, Kyungwon; Syahril Sulaiman; Lee, Jungeun; Bravo Leon A.; Saez Patricia L.; Lee, Hyoungseok Abstract: ？ Background and Aims Previous studies using open-topped chambers to simulate warming in Antarctic field conditions have shown distinct physiological responses between the two Antarctic vascular plants Colobanthus quitensis and Deschampsia antarctica. Colobanthus quitensis exhibited significantly increased photosynthetic capacity and growth during in situ warming conditions, whereas D. antarctica showed no differences in these parameters. To understand the differences in ecological strategies of these plants in response to climate change, it is important to elucidate the molecular mechanisms underlying physiological responses. ？ Methods Transcriptome profiling was performed on plants from open-topped chambers and a control open area on King George Island, after three growing seasons. Differential gene expression was analysed using RNA sequencing, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses to identify key biological processes affected by in situ warming. ？ Key Results Colobanthus quitensis exhibited significant upregulation of photosynthesis-related genes, including aquaporins, carbonic anhydrases and Rubisco activase, enhancing CO2 diffusion and assimilation. Conversely, D. antarctica showed downregulation of photosynthetic pathways but upregulation of genes related to flowering, including flowering-promoting factor and phytochrome-regulatory proteins. Both species showed molecular signatures suggesting reduced freezing tolerance in warming conditions, potentially increasing their susceptibility to frost damage. ？ Conclusions The results indicate distinct ecological strategies between the two plants in response to in situ warming. Colobanthus quitensis enhances its photosynthetic efficiency, whereas D. antarctica appears to accelerate its reproductive phase rather than focusing on growth. These findings contribute to our understanding of how Antarctic plants might respond to ongoing climate changes, with potential implications for their future resilience to extreme environmental conditions.

2025-05-01T00:00:00Z Jayram Karmacharya Prasansah Shrestha So-Ra Han Lee, Jun Hyuck Tae-Jin Oh https://repository.kopri.re.kr/handle/201206/16468 2026-01-14T07:38:48Z 2025-03-01T00:00:00Z

Title: Exploiting CotA laccase from Antarctic Bacillus sp. PAMC28748 for efficient mediator-assisted dye decolorization and ABTS regeneration Authors: Jayram Karmacharya; Prasansah Shrestha; So-Ra Han; Lee, Jun Hyuck; Tae-Jin Oh Abstract: Laccases are of particular interest in addressing environmental challenges, such as the degradation of triphenylmethane (TPM) dyes, including crystal violet (CV) and Coomassie Brilliant Blue (CBB), which are commonly used in SDS-PAGE for protein visualization. However, these dyes present significant environmental concerns due to their resistance to degradation, which makes their removal from industrial wastewater a major challenge. To address this, the current study investigates the potential of a novel CotA laccase derived from Bacillus sp. PAMC28748, an Antarctic bacterial isolate, for decolorizing these stubborn dyes. The CotA gene was successfully cloned and expressed, and the enzyme demonstrated optimal activity at pH 3 and 50 °C, which favors its maximum catalytic performance. The recombinant Bacillus sp. PAMC28748 rBCLac effectively decolorized CBB without additional mediators, whereas the degradation of CV required the use of the redox mediator ABTS. With ABTS, over 90 % decolorization was achieved at a 0.35 % concentration of CV after 240 min of incubation. Further investigation through molecular docking studies revealed that hydrogen bonding and hydrophobic interactions between the enzyme and the dye molecules are critical for effective degradation, highlighting the enzyme's specific interaction mechanisms. In addition to its catalytic effectiveness, the study also demonstrated the practical potential of the rBCLac system by recovering and reusing both ABTS and rBCLac through ultracentrifugation and acetone precipitation. The process maintained over 75 % efficiency across three cycles, despite a slight decline in enzyme activity, thus showcasing the system's sustainability and reusability. These findings collectively suggest that rBCLac, isolated from an extreme Antarctic environment, holds considerable promise as a candidate for the removal of industrial wastewater containing persistent dyes, with the added potential for cost-effective and sustainable water treatment through the reuse of both the enzyme and its mediator.

2025-03-01T00:00:00Z