Biomedical subjects

Sung-Hwan Cho

Publications and source records attributed to Sung-Hwan Cho.

5 recordsLinked to original sources

PubMed2025

Rice ETHYLENE RESPONSE FACTOR 101 increases leaf angle by upregulating BRASSINOSTEROID UPREGULATED 1.

The leaf angle (LA) is a critical component of plant architecture that directly influences photosynthetic efficiency and grain yield. In the present study, we found that ETHYLENE RESPONSE FACTOR 101 (OsERF101), an APETALA2/ethylene response factor, plays a role in LA formation. A null mutation in OsERF101 resulted in reduced LA, whereas transgenic plants overexpressing OsERF101 (OsERF101-OEs) exhibited increased LA. OsERF101 increased the development of the adaxial lamina joint (LJ). Transactivation assays and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis indicated that OsERF101 activated BRASSINOSTEROID UPREGULATED 1 (OsBU1) transcription by directly binding to its promoter. However, OsERF101 expression was suppressed by exogenous brassinosteroid (BR) treatment and elevated endogenous brassinolide (BL) levels during LJ development. Additionally, OsERF101 downregulated the expression of BR biosynthesis genes, including Brassinosteroid-deficient dwarf2 (OsBRD2) and CYP90B2/OsDWARF4, leading to reduced levels of endogenous BL, the most active BR, in OsERF101-OEs. These findings suggested that OsERF101 mediates a negative feedback loop that balances endogenous BR levels and signaling. Collectively, rice plants have evolved diverse regulatory mechanisms involving OsERF101 to tune LA formation and optimize plant architecture finely.

Oryza↗

PubMed2006

Rice Chlorina-1 and Chlorina-9 encode ChlD and ChlI subunits of Mg-chelatase, a key enzyme for chlorophyll synthesis and chloroplast development.

Photosynthetic organisms exhibit a green color due to the accumulation of chlorophyll pigments in chloroplasts. Mg-protoporphyrin IX chelatase (Mg-chelatase) comprises three subunits (ChlH, ChlD and ChlI) and catalyzes the insertion of Mg(2+) into protoporphyrin IX, the last common intermediate precursor in both chlorophyll and heme biosyntheses, to produce Mg-protoporphyrin IX (MgProto). Chlorophyll deficiency in higher plants results in chlorina (yellowish-green) phenotype. To date, 10 chlorina (chl) mutants have been isolated in rice, but the corresponding genes have not yet been identified. Rice Chl1 and Chl9 genes were mapped to chromosome 3 and isolated by map-based cloning. A missense mutation occurred in a highly conserved amino acid of ChlD in the chl1 mutant and ChlI in the chl9 mutant. Ultrastructural analyses have revealed that the grana are poorly stacked, resulting in the underdevelopment of chloroplasts. In the seedlings fed with aminolevulinate-dipyridyl in darkness, MgProto levels in the chl1 and chl9 mutants decreased up to 25% and 31% of that in wild-type, respectively, indicating that the Mg-chelatase activity is significantly reduced, causing the eventual decrease in chlorophyll synthesis. Furthermore, Northern blot analysis indicated that the nuclear genes encoding the three subunits of Mg-chelatase and LhcpII in chl1 mutant are expressed about 2-fold higher than those in WT, but are not altered in the chl9 mutant. This result indicates that the ChlD subunit participates in negative feedback regulation of plastid-to-nucleus in the expression of nuclear genes encoding chloroplast proteins, but not the ChlI subunit.

Alleles↗

PubMed2004

Electroacupuncture analgesia for surgery in cattle.

To establish the proper analgesic method by electroacupuncture (EA) for bovine surgery, the analgesic effect of dorsal and lumbar acupoints, in addition to the combination with dorsal and lumbar acupoints, were investigated in the present study. Four Korean native cattle (two males and two females) and 24 Holstein-Friesian cattle (all females) were used. The experimental animals were divided into four groups according to used acupoints: dorsal acupoint group (Tian Ping [GV-20] and Bai Hui [GV-5]: 7 heads), lumbar acupoint group (Yap Pang 1 [BL-21], Yao Pang 2 [BL-23], Yao Pang 3 [BL-24] and Yao Pang 4 [BL-25]; 5 heads), dorsal-lumbar acupoint group (Yao Pang 1 [BL-21], Yao Pang 2 [BL-23], Yao Pang 3 [BL-24] and Bai Hui [GV-5]; 8 heads) and control group (non-acupoints, the last intercostals space and the femoral area; 3 heads). The acupoints were stimulated with currents of 2-6 V (30 Hz) in dorsal acupoint group, 0.5-2.0 V (30 Hz) in lumbar acupoint group and 0.3-2.5 V (30 Hz) in dorsal-lumbar acupoint group. Recumbency time was 10 seconds to 1 minute (except one case) and induction time of analgesia was approximately 1 to 6 minutes in dorsal acupoint group. Analgesic effect was systemic, including the extremities in dorsal acupoint group. During the EA, the consciousness was evident and blepharo-reaction was still present under EA in dorsal acupoint group. During the surgery, grades of analgesic effect were 6 excellent (6/7, 87.5%) and 1 good (1/7, 14.3%). In addition, induction time for analgesia was about 10 minutes in both lumbar and dorsal-lumbar acupoint groups. Analgesic areas were found in abdominal areas from the last intercostal spaces to the femoral areas, except lower abdomen in lumbar and lumbar-dorsal acupoint groups. The consciousness was evident and standing position was maintained during EA stimulation in contrast to that of dorsal excellent (1/5, 20.0%), 3 good (3/5, 60.0%) and 1 poor (1/5, 20.0%) in the lumbar acupoint group. Additionally, grades of analgesic effect were 4 excellent (4/8, 50.0%), 3 good (3/8, 37.5%) and 1 poor (1/8, 12.5%). On the other hand, pain was present and analgesia was not accomplished under EA stimulation in control group. In conclusion, analgesia by EA was effective with decreasing order of dorsal acupoint > dorsal-lumbar acupoint > lumbar acupoint among groups. It was considered that dorsal acupoint group might be useful for operation with recumbent position, and lumbar and dorsal-lumbar acupoint groups might be proper for operation with standing position.

Acupuncture Analgesia↗

PubMed2004

The effectiveness of auriculoacupoint treatment for artificially induced acute hepatic injury in dogs.

This study was to investigate effects of auriculoacupoint (AAP) treatment on carbon tetrachloride (CCl4)-induced acute hepatic injury in ten dogs (four females and six males). Dogs have been divided into two groups: the control group (four dogs), not stimulated after induction of hepatic injury and the experimental group (six dogs), stimulated with AAP and massaged at the affected liver region of internal ear after induction of hepatic injury. Serum enzyme activities and histopathological findings were examined after the application of AAP. Compared to the control group, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in the experimental group were significantly decreased at the 4th day (p < 0.05) and at the 5th day (p < 0.05), respectively. Histopathological findings of the experimental group showed decrease of necrotic region and size of lipid droplets compared to the control group. In conclusion, AAP treatment had a therapeutic effect on the recovery of liver injury induced by CCl4 in dogs.

Acupuncture Points↗

PubMedDate not supplied

Gene regulation for the senescence marker protein DHEA-sulfotransferase by the xenobiotic-activated nuclear pregnane X receptor (PXR).

Dehydroepiandrosterone (DHEA)-sulfotransferase (SULT2A1) is a phase II metabolizing/detoxifying enzyme with substrate preference for physiological hydroxysteroids, diverse drugs and other xenobiotics. The first-pass tissues (liver and intestine) express SULT2A1 at high levels. In senescent male rodents, Sult2A1 gene transcription in the liver is markedly enhanced and calorie restriction retards this increase. Age-associated loss of the liver expression of androgen receptor in part explains the up-regulation of Sult2A1 expression at late life, since androgen receptor is a negative regulator of this gene. In line with its role in xenobiotic metabolism, the Sult2A1 gene is induced by the pregnane X receptor (PXR). PXR is a xenosensing nuclear receptor that is activated by endobiotic (natural steroids) and xenobiotic (therapeutic drugs and environmental chemicals) molecules. An inverted-repeat arrangement (IR0) of the consensus half site binding sequence for nuclear receptors mediates the xenobiotic induction of the Sult2A1 promoter. The IR0 element is a specific binding site for PXR and its heterodimer partner retinoid X receptor (RXR-alpha) and it directs PXR-mediated induction of a heterologous promoter. In contrast to the loss of androgen receptor expression, PXR and RXR-alpha mRNA expression is invariant during aging. Repression by the androgen receptor and induction by PXR may act coordinately to cause the senescence associated and xenobiotic mediated stimulation of Sult2A1 transcription. Increased Sult2A1 expression appears to be an adaptive response to ensure optimal metabolism of Sult2A1 substrates at old age.

Aging↗