Jeongwoong Yoon (Yoon)

All Publications

• Simple Transgene Overexpression using Scallop Hemocyte Culture Platform Enables Functional Genetic Research in Molluscs. Marine biotechnology (New York, N.Y.) Yoon, J., Tsuda, T., Bortoletto, E., Sakaguchi, A., Kobayashi, M., Rosani, U., Yokoi, H., Osada, M., Venier, P., Nagasawa, K. 2025; 27 (3): 94

  Abstract

  Despite being evolutionarily and commercially important, molluscs have been a traditionally challenging group to study, due to their difficulty in maintenance under lab conditions and the lack of a genetic toolkit. Previously, we showed that transgene expression can be attained in molluscan cells with reporter genes under a molluscan virus promoter sequence. Following up, we developed a simple, efficient and rapid transgene expression platform using primary hemocyte culture of Farrer's scallop Chlamys farreri, a marine bivalve mollusc. The protocol consists of two steps: collection and seeding of hemocytes and incubation for 1 to 4 days with DNA-reagent mixture. We evaluated seven transfection reagents for three bivalve species and found that X-tremeGENE 360 was highly efficient for DNA transfection, particularly for C. farreri. Subsequently, C. farreri hemocyte culture and transfection conditions were examined, such as culture medium, size and form of DNA, and the mixing ratio of DNA and transfection reagent. Using this protocol, we visualized the subcellular localization of four bivalve oncogenes, Cf-Mdm2-like, Cf-c-Myc-like, Cf-Mortalin-like, and Cf-Ras-like, tagged with EGFP. Our hemocyte platform provides an easy entry to study cellular and molecular biology of molluscs and can be readily adapted for advanced methods such as live imaging and DNA-protein interaction assays, making the study of molluscs more accessible to the scientific community.

  View details for DOI 10.1007/s10126-025-10472-7

  View details for PubMedID 40498244

  View details for PubMedCentralID 3776226

• Insights into ADAR gene complement, expression patterns, and RNA editing landscape in Chlamys farreri. Fish & shellfish immunology Bortoletto, E., Rosani, U., Sakaguchi, A., Yoon, J., Nagasawa, K., Venier, P. 2024; 151: 109743

  Abstract

  Adenosine Deaminases Acting on RNA (ADARs) are evolutionarily conserved enzymes known to convert adenosine to inosine in double-stranded RNAs and participate in host-virus interactions. Conducting a meta-analysis of available transcriptome data, we identified and characterised eight ADAR transcripts in Chlamys farreri, a farmed marine scallop susceptible to Acute viral necrosis virus (AVNV) infections and mortality outbreaks. Accordingly, we identified six ADAR genes in the Zhikong scallop genome, revised previous gene annotations, and traced alternative splicing variants. In detail, each ADAR gene encodes a unique combination of functional domains, always including the Adenosine deaminase domain, RNA binding domains and, in one case, two copies of a Z-DNA binding domain. After phylogenetic analysis, five C. farreri ADARs clustered in the ADAR1 clade along with sequences from diverse animal phyla. Gene expression analysis indicated CF051320 as the most expressed ADAR, especially in the eye and male gonad. The other four ADAR1 genes and one ADAR2 gene exhibited variable expression levels, with CF105370 and CF051320 significantly increasing during early scallop development. ADAR-mediated single-base editing, evaluated across adult C. farreri tissues and developmental stages, was mainly detectable in intergenic regions (83 % and 85 %, respectively). Overall, the expression patterns of the six ADAR genes together with the editing and hyper-editing values computed on scallops RNA-seq samples support the adaptive value of ADAR1-mediated editing, particularly in the pre-settling larval stages.

  View details for DOI 10.1016/j.fsi.2024.109743

  View details for PubMedID 38964433

• Hemocytes of Yesso scallop characterized by cytological, molecular marker, and functional analyses. Fish & shellfish immunology Nagasawa, K., Kanamori, M., Yoon, J., Kobayashi, M., Mokrina, M., Kato, T., Osada, M. 2023; 137: 108751

  Abstract

  Bivalve hemocytes have pivotal role as cellular biodefense. However, no information is available for cytological parameters, marker gene and function of the hemocytes in Yesso scallop, a commercially important aquaculture species worldwide. Due to their extremely strong cell aggregation ability, the scallop hemocytes were not able to assess as a single cell so far. In the present study, we established methodologies for studying the hemocytes of Yesso scallop, assessed cell morphology, measured seasonal fluctuation, and analyzed transcriptomes and cellular behavior during the immune response. Our results showed that the Yesso scallop possesses a single type of leukocyte-type hemocytes similar to other bivalve granulocytes circulating at an average of 1 × 107 cells/ml throughout the year. In addition, we identified five molecular marker genes specific to the scallop hemocytes. These hemocyte markers enabled us to precisely detect the hemocyte localization. Using these markers, we confirmed that tissue transplantation can experimentally induce an immune response, leading to the mobilization of circulating hemocytes for encapsulation. This study provides a comprehensive understanding of scallop hemocytes and their role in the cellular biodefense system of bivalves and various methods for cytological analysis.

  View details for DOI 10.1016/j.fsi.2023.108751

  View details for PubMedID 37105424

• Gene delivery available in molluscan cells by strong promoter discovered from bivalve-infectious virus. Proceedings of the National Academy of Sciences of the United States of America Yoon, J., Gu, W. B., Konuma, M., Kobayashi, M., Yokoi, H., Osada, M., Nagasawa, K. 2022; 119 (45): e2209910119

  Abstract

  Understanding gene functions in marine invertebrates has been limited, largely due to the lack of suitable assay systems. Such a system requires investigative methods that are reproducible and can be quantitatively evaluated, such as a cell line, and a strong promoter that can drive high expression of a transgene. In this study, we established primary cell culture from a marine bivalve mollusc, Mizuhopecten yessoensis. Using scallop primary cells, we optimized electroporation conditions for transfection and carried out a luciferase-based promoter activity assay to identify strong promoter sequences that can drive expression of a gene of interest. We evaluated potential promoter sequences from genes of endogenous and exogenous origin and discovered a strong viral promoter derived from a bivalve-infectious virus, ostreid herpesvirus-1 (OsHV-1). This promoter, we termed OsHV-1 promoter, showed 24.7-fold and 16.1-fold higher activity than the cytomegalovirus immediate early (CMV IE) promoter and the endogenous EF1α promoter, the two most commonly used promoters in bivalves so far. Our GFP assays showed that the OsHV-1 promoter is active not only in scallop cells but also in HEK293 cells and zebrafish embryos. The OsHV-1 promoter practically enables functional analysis of marine molluscan genes, which can contribute to unveiling gene-regulatory networks underlying astonishing regeneration, adaptation, reproduction, and aging in marine invertebrates.

  View details for DOI 10.1073/pnas.2209910119

  View details for PubMedID 36322729

  View details for PubMedCentralID PMC9661190