Dong Hee Lee’s research while affiliated with Korea Research Institute of Bioscience and Biotechnology and other places

Many of the β-glucans are known to have antihypertensive activities, but, except for angiotensin-converting enzyme II inhibition, the underlying mechanisms remain unclear. Corin is an atrial natriuretic peptide (ANP)-converting enzyme. Activated corin cleaves pro-ANP to ANP, which regulates water–sodium balance and lowers blood pressure. Here, we reported a novel antihypertensive mechanism of β-glucans, involved with corin and ANP in mice. We showed that multiple oral administrations of β-glucan induced the expression of corin and ANP, and also increased natriuresis in mice. Microarray analysis showed that corin gene expression was only upregulated in mice liver by multiple, not single, oral administrations of the β-glucan fraction of Phellinus baumii (BGF). Corin was induced in liver and kidney tissues by the β-glucans from zymosan and barley, as well as by BGF. In addition to P. baumii, β-glucans from two other mushrooms, Phellinus linteus and Ganoderma lucidum, also induced corin mRNA expression in mouse liver. ELISA immunoassays showed that ANP production was increased in liver tissue by all the β-glucans tested, but not in the heart and kidney. Urinary sodium excretion was significantly increased by treatment with β-glucans in the order of BGF, zymosan, and barley, both in 1% normal and 10% high-sodium diets. In conclusion, we found that the oral administration of β-glucans could induce corin expression, ANP production, and sodium excretion in mice. Our findings will be helpful for investigations of β-glucans in corin and ANP-related fields, including blood pressure, salt–water balance, and circulation.

Zoysia japonica Steud. is a native turfgrass in the Korean peninsula and is used worldwide. Abnormal conditions of soil salinity inhibit plant growth and adversely affect the quality of the turfgrass. AT-hook motif nuclear-localized (AHL) family proteins known to co-regulate the transcription of genes as a chromatin remodeling factor play a role in plant developmental processes and stress responses. In this study, AT-Hook Protein of Genomine 1 (ATHG1)/AT-Hook motif nuclear-Localized protein 23 (AHL23) and AT-hook Protein of Genomine 3 (ATPG3)/AT-Hook motif nuclear-Localized protein 20 (AHL20), two AHL genes from A. thaliana, were transformed into Z. japonica under the control of a constitutive ubiquitin promoter. Southern blot analysis proved that ATHG1/AHL23 and ATPG3/AHL20 were introduced into the ATHG1/AHL23-transgenic plants and ATPG3/AHL20-transgenic plants, respectively. Overexpression of each ATHG1/AHL23 and ATPG3/AHL20 in all of the transgenic plants was confirmed by quantitative real-time PCR (qRT-PCR). To evaluate a tolerant response to salt stress of the transgenic plants, 4 transgenic plants including ATHG1-overexpressing line 1 (ATHG1-OE1) and ATHG1-OE2, and ATPG3-overexpressing line 1 (ATPG3-OE1) and ATPG3-OE2 were selected, respectively. All the transgenic plants showed higher salt-tolerant phenotype with higher chlorophyll and lower malondialdehyde (MDA) contents under salt treatment, compared to the wild types. Also, under salt treatment, the transgenic plants revealed higher activities of catalase (CAT) and peroxidase (POD), reactive oxygen species (ROS)-scavenging enzymes, than those of the wild-type plant. These results suggest that overexpression of ATHG1/AHL23 or ATPG3/AHL20 belonging to the AHL gene family confers salt tolerance to the transgenic zoysiagrass plants.

The effects of taurine have been characterized primarily in mammals, and insects are not generally used to study taurine. In this study, ants were used to examine the effect of taurine on eusociality. Ants are the principal models for studying eusociality and superorganisms. Japanese carpenter ants (Camponotus japonicus) were fed a taurine-supplemented diet and tested using ant eusocial indexes. Ant farm structures were constructed using transparent PET bottles containing autoclaved soil. Three categories of vital index were used to study the effect of taurine on group activity: creation of formicaries (residence chambers), cooperative defense efforts, and population density (or group size and composition). Control, low-, and high-taurine diets were prepared using three different levels of taurine in sucrose powder: 0, 5, and 20% (g/g), respectively. The cooperative defense efforts against exogenous queen ants were recorded daily. The high-taurine group took less time to complete their defense formation than the other groups. At least 16% more formicaries (chambers) were observed in the taurine-fed groups than in the control. There were evident differences between control and taurine-fed groups in the total numbers of ants and eggs. The taurine-fed group sustained higher total numbers of ants, excluding the queen. Taurine-fed groups showed a significant increase both in the number of workers and eggs. When fed with taurine, ants responded positively on the eusocial vitality indexes. These results show that taurine exerts a positive effect on the eusociality of ants at the level of the superorganism.

Taurine is traditionally used to treat Down Syndrome (DS); however, the actual foundation for this treatment is not well understood. DS patients suffer from disturbance of the proteostasis network (PN) due to aberrant calcium signaling, which eventually causes endoplasmic reticulum stress (ERS). Taurine has been suggested to play a role in modulating calcium homeostasis and ERS. This study examined whether taurine affects DS symptoms using C. elegans - a DS model in which calcineurins, Ca2+/calmodulin-dependent protein phosphatase is mutated to null. The DS nematode model has short body length, slow growth, fertility defects, serotonin-resistant egg-laying defects, and faulty thermal sensing. This study focused on whether taurine may ameliorate the severity of DS at the whole-body level, including reduction in ERS. When treated with taurine, DS nematodes appeared to have lower levels of ERS and phenotypes closer to the wild type. DS nematodes also showed improved egg laying efficiency and thermal sensing index comparable to the wild type. Our findings offer a new perspective on the effectiveness of taurine in treating DS and designing therapeutic strategies to lower ERS and restore disrupted PN.

AT-hook proteins are known to co-regulate transcription of genes through the modification of chromatin architecture. In plants, many genes encoding AT-hook proteins have been shown to be associated with increased seed yield or delayed senescence. In this study, we produced transgenic soybean plants overexpressing chromatin architecture-controlling ATPG8 and ATPG10 genes by Agrobacterium-mediated transformation and examined their agronomic traits to identify the yield increase in soybean crop similar to those seen in model plants, Arabidopsis. A total of 16 (3 of pB2GW7.0-ATPG8 and 13 of pCSEN-ATPG10 transformed) transgenic soybean plants were produced and their T1 seeds were harvested. Healthy and well-grown transgenic lines were selected (lines #1 and #2 from pB2GW7.0-ATPG8, and lines #8 and #9 from pCSEN-ATPG10), and the insertion and transcription level of genes were confirmed by PCR and RT-PCR with expected size. Investigation on agricultural traits confirms the increase in yield, plant height, the number of pods, and total seed weight with statistical significance when compared to wild-type soybean plants. The yield component study suggested that overexpression of ATPG8 and ATPG10 genes conferred positive effect on yield in transgenic soybean.

Malonyl-ACP is a key building block for the synthesis of fatty acids, which are important components of cell membranes, storage oils, and lipid-signaling molecules. Malonyl CoA-acyl carrier protein (ACP) malonyltransferase (MCAMT) catalyzes the production of malonyl-ACP and CoA from malonyl-CoA and ACP. Here, we report that MCAMT plays a critical role in cell division and has the potential to increase the storage oil content in Arabidopsis. The quantitative RT-PCR and MCAMT promoter:GUS analyses showed that MCAMT is predominantly expressed in shoot and root apical meristems, leaf hydathodes, and developing embryos. The fluorescent signals of MCAMT:eYFP were observed in both chloroplasts and mitochondria of tobacco leaf protoplasts. In particular, the N-terminal region (amino acid residues 1 to 30) of MCAMT was required for mitochondrial targeting. The Arabidopsis mcamt-1 and -2 mutants exhibited an embryo-lethal phenotype because of the arrest of embryo development at the globular stage. The transgenic Arabidopsis expressing antisense MCAMT RNA showed growth retardation caused by the defects in cell division. The overexpression of MCAMT driven by the promoter of the senescence-associated 1 (SEN1) gene, which is predominantly expressed in developing seeds, increased the seed yield and storage oil content of Arabidopsis. Taken together, the plastidial and mitochondrial MCAMT is essential for Arabidopsis cell division and is a novel genetic resource useful for enhancing storage oil content in oilseed crops.

[This corrects the article on p. 413 in vol. 41.].

Soybean transgenic plants with ectopically expressed AtABF3 were produced by Agrobacterium-mediated transformation and investigated the effects of AtABF3 expression on drought and salt tolerance. Stable Agrobacterium-mediated soybean transformation was carried based on the half-seed method (Paz et al. 2006). The integration of the transgene was confirmed from the genomic DNA of transformed soybean plants using PCR and the copy number of transgene was determined by Southern blotting using leaf samples from T2 seedlings. In addition to genomic integration, the expression of the transgenes was analyzed by RT-PCR and most of the transgenic lines expressed the transgenes introduced. The chosen two transgenic lines (line #2 and #9) for further experiment showed the substantial drought stress tolerance by surviving even at the end of the 20-day of drought treatment. And the positive relationship between the levels of AtABF3 gene expression and drought-tolerance was confirmed by qRT-PCR and drought tolerance test. The stronger drought tolerance of transgenic lines seemed to be resulted from physiological changes. Transgenic lines #2 and #9 showed ion leakage at a significantly lower level (P < 0.01) than nontransgenic (NT) control. In addition, the chlorophyll contents of the leaves of transgenic lines were significantly higher (P < 0.01). The results indicated that their enhanced drought tolerance was due to the prevention of cell membrane damage and maintenance of chlorophyll content. Water loss by transpiration also slowly proceeded in transgenic plants. In microscopic observation, higher stomata closure was confirmed in transgenic lines. Especially, line #9 had 56% of completely closed stomata whereas only 16% were completely open. In subsequent salt tolerance test, the apparently enhanced salt tolerance of transgenic lines was measured in ion leakage rate and chlorophyll contents. Finally, the agronomic characteristics of ectopically expressed AtABF3 transgenic plants (T2) compared to NT plants under regular watering (every 4 days) or low rate of watering condition (every 10 days) was investigated. When watered regularly, the plant height of droughttolerant line (#9) was shorter than NT plants. However, under the drought condition, total seed weight of line #9 was significantly higher than in NT plants (P < 0.01). Moreover, the pods of NT plants showed severe withering, and most of the pods failed to set normal seeds. All the evidences in the study clearly suggested that overexpression of the AtABF3 gene conferred drought and salt tolerance in major crop soybean, especially under the growth condition of low watering.