Biology subjects

Kwon, S. J.

Publications and source records attributed to Kwon, S. J..

5 recordsLinked to original sources

bioRxiv2025

The heterochronic activation of TGF-β signaling drives the diversity of the avian sterna

Adaptive evolution has driven the diversification of vertebrate skeletal morphology, enabling a wide array of locomotor modes and lifestyles. In volant birds (carinates), the sternum develops a ventral keel that provides an attachment site for massive pectoral muscles essential for powered flight. In contrast, flightless ratites have lost both flight capability and the keel, resulting in a striking morphological contrast between their sterna. Here, we interrogated the cellular and molecular basis underlying this morphological divergence by using chicken embryos as a carinate model and emu embryos as a ratite model. Through a series of analyses including spatiotemporal transcriptomics and a spheroid culture system, we found that TGF-{beta} signaling, which promotes proliferation of ventral sternal chondroprogenitors, is activated in both species until the stage when the left and right sternal progenitors meet; however, in chicken this activation persists beyond this stage, driving ventral extension of the keel primordium, whereas in emu it shuts off early, culminating in the absence of a protruding keel. Together, our findings suggest that skeletal morphological changes associated with behavioral transitions can arise from heterochrony in developmental signaling, thereby deepening our understanding of the evolutionary logic shaping skeletal diversification.

developmental biology↗

bioRxiv2025

Optimization of culture and transfection methods for primary snake cells

Snakes serve as important models for understanding how changes in genes and genome sequences drive vertebrate morphological evolution. However, the lack of established primary culture methods and gene delivery techniques for snake cells has hindered functional analyses of evolutionarily modified genes and genomic elements. Here, we optimized primary culture conditions and screened for efficient transfection methods using corn snake embryonic fibroblasts. Our culture optimization experiments revealed that TeSR medium, designed for stem cells, with fetal bovine serum supplementation, and incubation at 28 provided a suitable condition for primary snake fibroblasts. Transcriptome analysis further demonstrated that under this optimized condition, genes associated with cytoskeletal organization, extracellular matrix components, and sterol biosynthetic process were upregulated, likely promoting snake cell proliferation. Additionally, screening of various gene transfection methods identified three efficient approaches, including electroporation. These findings enhance the utility of snake cells and pave the way for functional analyses of genes and genomic elements using snake cell-based systems.

developmental biology↗

bioRxiv2021

The Arabidopsis ORA59 coordinates jasmonic acid- and ethylene-responsive gene expression to regulate plant immunity

Jasmonic acid (JA) and ethylene (ET) signaling modulate plant defense against necrotrophic pathogens. These hormone pathways lead to transcriptional reprogramming, which is a major part of plant immunity and requires the roles of transcription factors. ET response factors are responsible for the transcriptional regulation of JA/ET-responsive defense genes, among which ORA59 functions as a key regulator of this process and has been implicated in the JA-ET crosstalk. Here, we identified the ERELEE4 as an ORA59-binding cis-element, in addition to the well-characterized GCC box, demonstrating that ORA59 regulates JA/ET-responsive genes through direct binding to these elements in the gene promoters. Notably, ORA59 exhibited differential preference for the GCC box and ERELEE4, depending on whether ORA59 activation is achieved by JA and ET, respectively. Our results provide insights into how ORA59 can generate specific patterns of gene expression dynamics through JA and ET hormone pathways.

plant biology↗

bioRxiv2019

Identification of Ca-rich dense granules in human platelets using scanning transmission X-ray microscopy

Whole mount (WM) platelet preparations followed by transmission electron microscopy (TEM) observation is the standard method currently used to assess dense granule (DG) deficiency (DGD). However, due to electron density-based contrast mechanism in TEM, other granules such as -granules might cause false DGs detection. Herein, scanning transmission X-ray microscopy (STXM), was used to identify DGs and minimize false DGs detection of human platelets. STXM image stacks of human platelets were collected at the calcium (Ca) L2,3 absorption edge and then converted to optical density maps. Ca distribution maps obtained by subtracting the optical density map at pre-edge region from those obtained at post-edge region were used for identification of DGs based on richness of Ca. Dense granules were successfully detected by using STXM method without false detection based on Ca maps for 4 human platelets. Spectral analysis of granules in human platelets confirmed that DGs contained richer Ca content than other granules. Image analysis of Ca maps provided quantitative parameters which would be useful for developing image-based DG diagnosis models. Therefore, we would like to propose STXM as a promising approach for better DG identification and DGD diagnosis, as a complementary tool to the current WM TEM approach.

biophysics↗

bioRxiv2019

Mass Cytometry Study on the Heterogeneity in Cellular Association and Cytotoxicity of Silver Nanoparticles in Human Immune Cells

There have been many reports about the adverse effects of nanoparticles (NPs) on the environment and human health. Conventional toxicity assessments of NPs frequently assume uniform distribution of monodisperse NPs in homogeneous cell populations, and provide information on the relationships between the administered dose of NPs and cellular responses averaged for a large number of cells. They may have limitations in describing the wide heterogeneity of cell-NP interactions, caused by cell-to-cell and NP-to-NP variances. To achieve more detailed insight into the heterogeneity of cell-NP interactions, it is essential to understand the cellular association and adverse effects of NPs at single-cell level. In this study, we applied mass cytometry to investigate the interactions between silver nanoparticles (AgNPs) and primary human immune cells. High dimensionality of mass cytometry allowed us to identify various immune cell types and observe the cellular association and toxicity of AgNPs in each population. Our findings showed that AgNPs had higher affinity with phagocytic cells like monocytes and dendritic cells and caused more severe toxic effects than with T cells, B cells and NK cells. Multi-element detection capability of mass cytometry also enabled us to simultaneously monitor cellular AgNP dose and intracellular signaling of individual cells, and subsequently investigate the dose-response relationships of each immune population at single-cell level, which are often hidden in conventional toxicity assays at bulk-cell level. Our study will assist future development of single-cell dose-response models for various NPs and will provide key information for the safe use of nanomaterials for biomedical applications.

biochemistry↗