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Prediction of Daphnia Production along a Trophic Gradient
Park, Sangkyu*,C.R. Goldman 한국생태학회 2008 Journal of Ecology and Environment Vol.31 No.2
To predict Daphnia secondary productivity along a trophic gradient indexed as total phosphorus(TP) concentration, we estimated energy transfer efficiencies from food quality for Daphnia such as eicosa-Daphnia magna growth experiments were conducted with seston from 9 lakes, ponds and river waters. Primary productivities were estimated from food supply rates in the flow-through experiments, producing energy transfer efficiencies from seston to D. magna. We found DHA content was the best predictor of energy transfer efficiencies among the essential fatty acids. An asymptotic saturation model explained 79.6% of the variability in energy transfer effi-ciencies. Based on empirical data in this study and empirical models from literature, we predict that Daphnia productivity would peak in mesotrophic systems by decreasing food quality and increasing food quantity along trophic gradient.
( Sangkyu Park ),( Dongbum Kim ),( Jinsoo Kim ),( Hyung-joo Kwon ),( Younghee Lee ) 생화학분자생물학회 2023 BMB Reports Vol.56 No.12
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to various clinical symptoms including anemia. Lipocalin-2 has various biological functions, including defense against bacterial infections through iron sequestration, and it serves as a biomarker for kidney injury. In a human protein array, we observed increased lipocalin-2 expression due to parental SARS-CoV-2 infection in the Calu-3 human lung cancer cell line. The secretion of lipocalin-2 was also elevated in response to parental SARS-CoV-2 infection, and the SARS-CoV-2 Alpha, Beta, and Delta variants similarly induced this phenomenon. In a Calu-3 implanted mouse xenograft model, parental SARSCoV- 2 and Delta variant induced lipocalin-2 expression and secretion. Additionally, the iron concentration increased in the Calu-3 tumor tissues and decreased in the serum due to infection. In conclusion, SARS-CoV-2 infection induces the production and secretion of lipocalin-2, potentially resulting in a decrease in iron concentration in serum. Because the concentration of iron ions in the blood is associated with anemia, this phenomenon could contribute to developing anemia in COVID-19 patients. [BMB Reports 2023; 56(12): 669-674]
Rice P450 reductases differentially affect P450-mediated metabolism in bacterial expression systems.
Park, Sangkyu,Kim, Young-Soon,Rupasinghe, Sanjeewa G,Schuler, Mary A,Back, Kyoungwhan Springer-Verlag 2013 Bioprocess and biosystems engineering Vol.36 No.3
<P>We describe cloning and characterization of three rice (Oryza sativa) NADPH-cytochrome P450 reductases (OsCPRs; E.C.1.6.2.4) that are potential donors to plant P450s, including tryptamine 5-hydroxylase (T5H) in serotonin synthesis and cinnamate 4-hydroxylase (C4H) in phenylpropanoid synthesis. All three OsCPR transcripts are induced to varying degrees by stresses. Co-expression of full-length OsCPR1, OsCPR2 and OsCPR3 with either T5H or C4H in E. coli indicated that the OsCPR2/T5H and OsCPR2/C4H constructs displayed the highest T5H and C4H catalytic activities. The N-terminal residues of OsCPR2 were required for peak electron transfer activity to P450 even though deletion mutants with short N-terminal deletions were capable of reducing cytochrome c.</P>
Park, Sangkyu,Ku, Youn Kyoung,Seo, Mi Ja,Kim, Do Young,Yeon, Ji Eun,Lee, Kyung Min,Jeong, Soon-Chun,Yoon, Won Kee,Harn, Chee Hark,Kim, Hwan Mook Elsevier 2006 Soil biology & biochemistry Vol.38 No.8
<P><B>Abstract</B></P><P>To assess the impact of a transgenic crop on soil environment, we compared soil bacterial communities from the rhizospheres of cucumber green mottle mosaic virus (CGMMV)-resistant transgenic watermelon (<I>Citrullus vulgaris</I> [Twinser] cv. Gongdae) and non-transgenic parental line watermelon at an experimental farm in Miryang, Korea. Soil microbial community structure was studied using terminal restriction fragment length polymorphism (T-RFLP) using <I>Hae</I>III and <I>Hha</I>I enzymes on products from polymerase chain amplification reactions (PCR) of total DNA from rhizosphere. We used principal component analyses (PCA) to reduce dimensionality of T-RFLP profiles before comparison. On these PCA scores, we conducted discrimination analyses to compare soil microbial communities from the rhizosphere of transgenic and non-transgenic. Discriminant analyses indicate that microbial communities from rhizosphere of transgenic and non-transgenic watermelon did not differ with significance at 95% level. Our study could be used as a model case to assess the environmental risk assessment of transgenic crops on soil microbial organisms.</P>
Tryptophan Boost Caused by Senescence Occurred Independently of Cytoplasmic Glutamine Synthetase
PARK, Sangkyu,LEE, Kyungjin,KANG, Kiyoon,KIM, Young Soon,LEE, Sungbeom,KWEON, Soon-Jong,BACK, Kyoungwhan Japan Society for Bioscience, Biotechnology, and A 2010 Bioscience, Biotechnology, and Biochemistry Vol.74 No.11
<P>We examined to determine whether senescence-induced tryptophan levels are positively associated with levels of glutamine synthetase (GS1), the initial enzyme in tryptophan biosynthesis. We generated transgenic rice plants in which GS1 was suppressed by RNA interference technology. The transgenic line showed a dramatic decrease in GS1 protein and glutamine content, but the levels of tryptophan and mRNA of the key tryptophan biosynthetic genes upon senescence were comparable to those of the wild type.</P>
Plant Metabolomics for Plant Chemical Responses to Belowground Community Change by Climate Change
Park, Sangkyu,Seo, Young-Su,Hegeman, Adrian D. 한국식물학회 2014 Journal of Plant Biology Vol.57 No.3
General circulation models on global climate change predict increase in surface air temperature and changes in precipitation. Increases in air temperature (thus soil temperature) and altered precipitation are known to affect the species composition and function of soil microbial communities. Plant roots interact with diverse soil organisms such as bacteria, protozoa, fungi, nematodes, annelids and insects. Soil organisms show diverse interactions with plants (eg. competition, mutualism and parasitism) that may alter plant metabolism. Besides plant roots, various soil microbes such as bacteria and fungi can produce volatile organic compounds (VOCs), which can serve as infochemicals among soil organisms and plant roots. While the effects of climate change are likely to alter both soil communities and plant metabolism, it is equally probable that these changes will have cascading consequnces for grazers and subsequent food web components aboveground. Advances in plant metabolomics have made it possibile to track changes in plant metabolomes as they respond to biotic and abiotic environmental changes. Recent developments in analytical instrumentation and bioinformatics software have established metabolomics as an important research tool for studying ecological interactions between plants and other organisms. In this review, we will first summarize recent progress in plant metabolomics methodology and subsequently review recent studies of interactions between plants and soil organisms in relation to climate change issues.