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The history of past hydroclimatic extreme events, essential information for predicting future changes, is preserved in fluvial sediments. Here, we reconstruct changes in decadal-scale extreme flooding events over the period 7700–1700 cal yr BP from floodplain sediments in the middle reach of the Nakdong River, Korea, based on lithogenic elemental ratios (e.g., Zr/Ti and Sr/Si). For example, Nakdong extreme flooding (NEF) events frequently occurred at 7700, 7200, 6000, 5000, 3800, 3200, 2900, 2600, 2300, 2000, and 1700 cal yr BP, and were associated with higher sea-surface temperatures and strong El Niño-Southern Oscillation (ENSO) activity. Notably, we found a significant change in the frequency of extreme events ca. 3700 cal yr BP over East Asia. The hydroclimate fluctuated with dominant periodicities of 950 and 540 years in 7700–3700 cal yr BP and shorter centennial to decadal cycles (320, 110–120, and 60–75 years) in 3700–1700 cal yr BP. This 3.7-ka climatic shift is consistent with a marked southward shift of the intertropical convergence zone, intensified ENSO activity, increased frequency of recurving typhoons, and deep-ocean circulation changes in both the northern and southern hemispheres, demonstrating the urgent need for investigating the critical role of past deep-water circulation in hydroclimate changes.

Phytoclasts in the form of plant debris in terrestrial sediments can be transported by water to distant areas because they are lighter than inorganic particles. The semi-enclosed East Sea, which is connected by narrow straits to other seas, is adjacent to continental shelves that are the source area of terrestrial sediment flowing into the East Sea. These shelves alternated repeatedly between terrestrial and marine environments as a result of eustatic sea-level changes during the Late Quaternary. Palynofacies analyses of the IODP Exp. 346 U1430 core, located in the Eastern South Korea Plateau (ESKP) of the East Sea, have revealed changes in the size and concentration of phytoclasts associated with glacial–interglacial cycles. These changes are generally negatively correlated with the global sea-level curve, and their anti-phase cycles with high amplitude are clearly evident during the last ca. 750 ka with the geotectonic stabilization period. In particular, several coarse-grained phytoclasts were observed during the glacial period, including the Last Glacial Maximum (LGM). These findings suggest that the concentration and size of phytoclasts flowing into the East Sea were influenced by changes in the distance of the source area, depending on the water depth of the strait and nearby shelves owing to sea-level changes in tandem with glacial–interglacial cycles and geotectonic events.

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.

Three long marine cores collected from the southwestern part of the Ulleung Basin in the East Sea were investigated in terms of chronology, from the middle Pleistocene to Holocene. We propose an age–depth model in cores 19ESDP-101, 19ESDP-103, and 19ESDP-104 obtained through precise age data using a suitable statistical method and classified in chronological units according to their accumulation rates. Changes in accumulation rate in cores 19ESDP-103 and 19ESDP-104, located at the entrance to the contact of the Korean Strait and the Ulleung Basin, showed good agreement with glacial and interglacial cycles. Relatively increased accumulation rates are related to ocean currents flowing through the Korea Strait during interglacial periods of Marine Isotope Stage (MIS) 5 and 7. However, core 19ESDP-101 obtained from the Hupo Basin, located in the northern site, showed a high accumulation rate in the glacial periods of MIS 6 and 8. It is interpreted as an increase in the sediment input from the exposed shallow shelf and inland fluvial, despite the fact that ocean currents from the Korea Strait are blocked by the exposed shelf platform as the sea-level falling down. These results show that the continental shelf on the western East Sea has been deposited from various factors related to several sea-level fluctuations from the glacial-interglacial cycle during the middle to late Quaternary. This study contributes to stratigraphic study in the Korean continental shelf environment of the East Sea from the middle Pleistocene to Holocene.

Mesenchymal stromal cells (MSCs) differentiation into different lineages is precisely controlled by signaling pathways. Given that protein kinases play a crucial role in signal transduction, here we show that Microtubule Associated Serine/Threonine Kinase Family Member 4 (Mast4) serves as an important mediator of TGF-β and Wnt signal transduction in regulating chondro-osteogenic differentiation of MSCs. Suppression of Mast4 by TGF-β1 led to increased Sox9 stability by blocking Mast4-induced Sox9 serine 494 phosphorylation and subsequent proteasomal degradation, ultimately enhancing chondrogenesis of MSCs. On the other hand, Mast4 protein, which stability was enhanced by Wnt-mediated inhibition of GSK-3β and subsequent Smurf1 recruitment, promoted β-catenin nuclear localization and Runx2 activity, increasing osteogenesis of MSCs. Consistently, Mast4 −/− mice demonstrated excessive cartilage synthesis, while exhibiting osteoporotic phenotype. Interestingly, Mast4 depletion in MSCs facilitated cartilage formation and regeneration in vivo. Altogether, our findings uncover essential roles of Mast4 in determining the fate of MSC development into cartilage or bone. Controlling fate decision of mesenchymal stromal cells (MSC) is important for their clinical application. Here the authors demonstrate that TGF-β-induced Mast4 suppression and Wnt-mediated Mast4 stabilization regulate MSC differentiation into cartilage and bone, respectively.

Jung-Hyun Lee, Jong Bhak and their colleagues report the whole-genome sequencing and de novo assembly of a male minke whale genome, as well as the genome sequences of three additional minke whales, a fin whale, a bottlenose dolphin and a finless porpoise. Their comparative analysis across cetaceans provides insights into adaptation to an aquatic lifestyle. The shift from terrestrial to aquatic life by whales was a substantial evolutionary event. Here we report the whole-genome sequencing and de novo assembly of the minke whale genome, as well as the whole-genome sequences of three minke whales, a fin whale, a bottlenose dolphin and a finless porpoise. Our comparative genomic analysis identified an expansion in the whale lineage of gene families associated with stress-responsive proteins and anaerobic metabolism, whereas gene families related to body hair and sensory receptors were contracted. Our analysis also identified whale-specific mutations in genes encoding antioxidants and enzymes controlling blood pressure and salt concentration. Overall the whale-genome sequences exhibited distinct features that are associated with the physiological and morphological changes needed for life in an aquatic environment, marked by resistance to physiological stresses caused by a lack of oxygen, increased amounts of reactive oxygen species and high salt levels.

Illicium anisatum , an ancient angiosperm belonging to the ANITA grade, contains abundant plant metabolites with antimicrobial activity, including shikimate and sesquiterpene lactones (STLs) such as anisatin. The aim of this study was to generate a full-length transcriptome resource for identifying genes related to the shikimate and STL biosynthetic pathways in I. anisatum and for studying the evolution of Illicium species. We performed RNA isoform sequencing of I. anisatum leaf, stem, flower, and floral bud samples and annotated the assembled transcripts based on a homology search. A total of 148,593 transcripts with an average length of 2.2 kb and high assembly completeness were generated. Functional pathway analysis revealed the evolutionary conservation of the shikimate and aromatic amino acid (AAA) biosynthetic pathways in I. anisatum and the upregulation of genes that encode chorismite synthase, which is highly associated with the production of shikimate and serve as a precursor for the biosynthesis of AAAs, in floral organs. I. anisatum germacrene A oxidase (IaGAO) and germacrene D synthase (IaGDS), which participate in STL biosynthesis, showed evolutionary divergence from their homologs in the plants of the family Asteraceae, and their genes were mainly expressed in flower organs. Interestingly, alternative splicing isoforms of IaGDS transcripts were found, probably resulting in differential expression in flower and floral bud. We also constructed a map of the I. anisatum chloroplast genome. Isoform sequencing provided a high level of transcriptome assembly completeness and gene annotation and enabled effective prediction of protein domains. The reported long-read sequencing-based de novo assembly of the I. anisatum transcriptome should aid in exploring genes related to the shikimate and STL biosynthesis pathways and associated molecular mechanisms in Illicium species.