https://repository.kopri.re.kr/handle/201206/15689 Mon, 06 Apr 2026 10:04:37 GMT 2026-04-06T10:04:37Z https://repository.kopri.re.kr/handle/201206/16616 Title: Exogenous abscisic acid enhances freeze-thaw stress tolerance in Antarctic moss Sanionia uncinata through coordinated antioxidant defense and osmoprotectant accumulation Authors: Seo, Suyeon; Ahn, Yong-Yoon; Kim, Kitae; Lee, Jun Hyuck; Min, Kyungwon; Lee, Hyoungseok Abstract: Abscisic acid (ABA) is known to improve plant freeze-thaw stress tolerance (FTST), but its role in Antarctic mosses remains largely unexplored. Accordingly, this study investigated the effects of exogenous ABA application on FTST of gametophore Sanionia uncinata, one of the most widespread moss species in maritime Antarctica. Samples were treated with 10 mu M ABA for 72 h under controlled culture conditions, then subjected to freezing stress at -13 and -16 degrees C. Various physiological parameters were measured to assess ABA-induced FTST, including ion-leakage, photosynthetic efficiency (Fv/Fm), malondialdehyde (MDA) content, compatible solutes/osmolytes (proline and total sugars), and antioxidant enzyme activities, e.g., superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). Gametophores treated with ABA efficiently assimilated ABA, evident by similar to 20-fold higher than controls. ABA application did not impede gametophore growth but slightly increased dry weight/fresh weight ratio (5 % increase). ABA significantly improved freezing tolerance, reducing freeze-induced membrane injury by similar to 20 % at both stress temperatures, alleviating oxidative stress with 25-34 % lower MDA accumulation, and enhancing PSII maximum quantum yield (Fv/Fm) by 6-7 % following freeze-thaw stress. Improved FTST was paralleled by enhanced activities of antioxidant enzymes, CAT and APX increasing by similar to 11 % and 56 %, respectively, while SOD remained unchanged. ABA treatment also promoted osmoprotectant accumulation, with proline content increasing by 33.5 % and total soluble sugars nearly doubling (99 % increase). These findings provide the first quantitative evidence that exogenous ABA markedly improves FTST in an Antarctic moss through coordinated antioxidant defense and osmoprotectant accumulation, highlighting ABA as a critical regulator of stress resilience in S. uncinata. Mon, 01 Dec 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16616 2025-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16084 Title: Secondary Metabolites Isolated from the Methanol Extract of Pseudocyphellaria freycinetii and Their Cytotoxicity Authors: Koo, Man Hyung; Kim, Hye Ji; Kim, Seong Hye; Youn, Ui Joung Abstract: Phytochemical study of the lichen, Pseudocyphellaria freycinetii (Lobariaceae) led to the isolation of two hopane-type triterpenoids (1 and 2), along with two phenolic compounds (3 and 4). The structures of the compounds were identified by 1D and 2D NMR, and MS experiments, as well as by comparison of their data with published values. Compounds 2-4 were isolated for the first time in this species. All the compounds were evaluated for their cytotoxicity. Among the isolates, compound 1 showed considerable inhibitory activity against the Hela cell growth. Sun, 01 Jun 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16084 2025-06-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16615 Title: Exploring the Anti-Inflammatory Potential of a Steroidfrom Antarctic Lichen Umbilicaria antarctica(L.)Ach.: In Vitro, In Vivo Zebra fish Assay, and In Silico Studies Authors: Jae HeonSim; Sung WooShin; Eun Jin Heo; Na Woo Kim; Lee, Jun Hyuck; Youn, Ui Joung; Tong Ho Kang; Seulah Lee Abstract: Chemical analysis of the Antarctic lichen Umbilicaria antarctica (L.) Ach. led to the isolation of four compounds (1？4). Among these, 9,11-dehydroergosterol peroxide (3) demonstrated the most substantial anti-inflammatory effects both in vitro and in vivo using zebrafish models. Molecular docking studies were conducted to assess the binding affinities of the selected compounds with important inflammatory mediators iNOS and IL-10, and molecular dynamics (MD) simulations were performed on the most potent anti-inflammatory compound. RMSD plot analysis indicated that 3 remained stable throughout a 200 ns simulation period, particularly with iNOS. RMSF plots also suggested a stable and well-fitted conformation of 3 within the binding site of iNOS. The complex stability during the simulation is attributable to the hydrophobic interactions of 3 with TRP463, which contributed over 40% to the protein-ligand interactions. These findings suggest that 9,11-dehydroergosterol peroxide (3) could be a promising new strategy for treating inflammation. Thu, 01 May 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16615 2025-05-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16586 Title: CAZyme analysis and functional characterization of a new GH18 chitin hydrolase from Gelidibacter salicanalis PAMC21136 Authors: Lakshan Paudel; Bashu Dev Pardhe; So-Ra Han; Lee, Jun Hyuck; Tae-Jin Oh Abstract: Gelidibacter salicanalis strains remain poorly understood in terms of their genomic attributes and are rarely reported for the degradation of polysaccharides within the niche. Gelidibacter salicanalis PAMC21136, an Antarctic isolate, was sequenced and functionally annotated. 251 genes were classified into the CAZyme families, which includes the highest number of GH family, highlighting peculiarity towards various macro biopolymers. Further, based on domain architecture and multiple sequence alignment, gene belonging to the family18 glycoside hydrolase was identified as chitinase. The gene encoding chitinase (MBJ7879808.1) was successfully cloned and expressed in Escherichia coli BL21 cells. MBJ7879808.1 demonstrated activity towards colloidal chitin but there was no detectable activity towards microcrystalline crab shell chitin. Enzyme exhibited an exo-pattern of hydrolysis on both colloidal chitin, and shorter chain GlcNAc oligomers namely [(GlcNAc)3, (GlcNAc)4, (GlcNAc)5, and (GlcNAc)6] producing GlcNAc as a single final product. Biochemical characterization revealed an optimum activity at 25 °C and pH 7.0. Mn²? ions significantly enhanced the activity by 1.7-fold. Turnover number (Kcat) was 8.6 min?1 and catalytic efficiency (Kcat/Km) was 2.0ml/mg/min towards the substrate colloidal chitin. These findings expanded the polysaccharide degradation capability of Gelidibacter salicanalis PAMC21136 and highlight the biotechnological potential of the GH18 enzyme towards production of chitooligomers. Sat, 01 Mar 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16586 2025-03-01T00:00:00Z