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Newly recognized phosphine resistance mechanisms in the rice weevil, Sitophilus oryzae
Sung-Eun Lee,Kyeongnam Kim,Jeong Oh Yang,Yonglin Ren,Byung-Ho Lee 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.10
Phosphine (PH3) resistance in the stored-products insect pests has been reported throughout the world in various insect species, including Rhyzopertha dominica, Tribolium castaneum, and Cryptolestes ferrugineus, leading farmers and fumigators to identify new fumigation tools to control PH3-resistant insect pests in storage facilities. Understanding PH3-resistance mechanisms in insects might contribute to providing clues for the development of new chemicals, including fumigants, to control various PH3-resistant insects. A proteomic study has shown 15 decreased proteins in the PH3-resistant R. dominica (CRD343 strain) in comparison to the PH3-susceptible R. dominica, and among those 15 proteins, dihydrolipoamide dehydrogenase (DLD), a protein involved in the Krebs cycle, was identified (Park et al., 2008). The DLD polymorphisms responsible for genetic resistance have disulfide active sites for PH3 binding and are highly sensitive to arsenic exposure after mutagenesis in insects (R. dominica and T. castaneum) and Caenorhabditis elegans (Schlipalius et al., 2012). Here, two PH3- resistant S. oryzae strains were used to understand the development of PH3 resistance in these insects. Acute toxicity test by PH3 on the two PH3-resistant strains was undertaken followed by ethyl formate inhibition study on cytochrome c oxidase activity. The Lineweaver-Burk plots after inhibition studies showed there were significantly difference in inhibition mode between the resistant strains and the control. The RT-qPCR analysis and the next-generation sequencing of the mitochondrial DNA revealed significant changes in metabolism and energy production. Taken together, the PH3 resistance in S. oryzae was definitely acquired by the overall transformation of biochemical reactions to overcome PH3 toxicity.
A Spectrophotometric Assay for Cytochrome P450 Monooxygenase Activity
( Sung Eun Lee,Won Sik Choi,Byeoung Soo Park,Byung Ho Lee ) 한국응용생명화학회 1998 Applied Biological Chemistry (Appl Biol Chem) Vol.41 No.4
An assay for cytochrome P450 monooxygenase activity by determination of the products of organophosphate oxidation via inhibition of acetylcholinesterase was described. Extracts from strains of Orzaephilus surinamensis selected for resistance to chlorpyrifos-methyl (QVOS 102), fenitrothion (VOS F) and malathion (VOS 3), and a standard susceptible strain VOS 48, were incubated with an organophosphate in the presence of a NADPH-generating system and acetylcholinesterase. The degree of inhibition of the acetylchoinesterase activity was converted to manooxygenase activity using standard curves for the inhibition of acetylcholiesterase by chlorpyrifos-methyl-oxon, fenitrooxon and malaoxan. Activity was detectable in VOS 48 and was present at different increased levels with the different organophosphates in the three resistant strains, suggesting that different forms of P450 might be involved in organophosphate oxidation in these insects. The assays were carried out using crude insect homogenates and much smaller samples of insect material than the standard aldrin to dieldrin assay. It should be possible to use the method for determination of monooxygenase activity in single insert.
Sungeun Lee,Myeongsu Han,Daesik Hong IEEE 2009 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.8 No.6
<P>In the paper, we deal with a single-selection opportunistic relaying with the decode-and-forward (DF) protocol over Rayleigh fading channels. The exact end-to-end average signal-to-noise ratios (SNR) and ergodic capacities of both proactive and reactive opportunistic relaying are derived as a closed-form for arbitrary link SNR. In addition, the effective ergodic capacity satisfying the minimum required data rate without outage is also identified for both relaying schemes. The analysis results are used to demonstrate which relaying scheme outperforms the other for given system parameters.</P>
Role of INSL3 during folliculogenesis in mice ovary
Sung Eun Lee,Yong-Pil Cheon,Chemyoung Ko 한국발생생물학회 2010 한국발생생물학회 학술발표대회 Vol.29 No.-
Insulin like3 (INSL3, Relaxin like factor) is a critical regulator in testis translocation through Leucin rich G-protein coupled receptor 8 (Rxfp2,LGR8) during embryogenesis. In female, INSL3 and their receptor expressed in growing follicle and revealed their function in oogenesis. However, its role is not much evaluated. 6 weeks old C57BL/6 female mice used for measure the expression of INSL3 mRNA and their receptor expression by follicular stage. Follicle cell specific RNA were got from the theca cell and granulose cells which were isolated using LCM. To know the role of INSL 3 in theca cell, Rxpf2 were overexpressed during primary culture of theca cells, which were isolated from tertiary follicles after 12 hr PMSG injection and transduced the Rxfp2 using lenti virus. After 10 days of culture, the proliferation of theca cells was analyzed using EdU. Using Alzet osmotic pumps INSL3 was administered for 3 days into the ovary during superovulation induction. The INSL3 mRNA levels were significantly high in the theca cells of preovulator follicles after hCG injection. But granulose cells showed decreasing expression by growth of follicle. INSL3 stimulated the proliferation of theca cells in vitro which overexpressed the Rxpf2. By the administration of INSL3 into ovary caused the dramatical decrease the number of ovulated oocyte. Based on these results, we know that INSL3 stimulates the theca cell proliferation in as follicle stage specific manners, and estrogen is a modulator of this INSL3 mRNA expression. It suggests that the disturbance of the expression regulation of INSL3 and its receptor cause the unregulated theca cell proliferation and failing the rupture of grown follicle.
Profiles of SULT1E1 expression in tiEsr1KO mice during folliculogenesis
Sung Eun Lee,Yong-Pil Cheon 한국발생생물학회 2011 한국발생생물학회 학술발표대회 Vol.30 No.-
Sulfotransferase 1E1 (SULT1E1, EST) is responsible for the sulfation and inactivation of betaestradiol at physiological concentrations. SULT1E1 null mice have reduced fertility by the disfunction of placenta and ovulation. Based our previous data it was revealed that the ovulation ability of 6-month old tiEsr1KO female mice is similar with the SULT1E1 female mice. In this study the possible relations in ovulation between estrogen and SULT1E1 was examined using real-time PCR and RIA methods in tiEsr1KO model mice. During the induction of superovualtion SULT1E1 gene expression peaked just before ovulation (6 hr posthCG injection) in control mice. As expected the expression patterns were similar between control and 4-weelk old tiEsr1KO female mice. Serum levels of E2 were increased in both tiEsr1KO mice and wild type mice but its level was higher 3 times in tiEsrKO mice than the wild type. Its levels became same between them after hCG administration. On the other hand, 6-month old mice shows the the dramatical increasing the SULT 1E1 expression during folliculogenesis, their expression was increased more than 100 times after hCG 6hr compared with PMSG 12hr control. In contrast with the 4-week old tiEsr1KO female mice, the expression levels of SULT1E1 gene expression were higher levels more than 20 times at 12 hr post PMSG injection. On the other hand, the expression levels of the other SULT family genes, SULT1A1 and SULT2A1 were very low compared with the SULT1E1 and did not show fluctuation during that period. Based on these results, it is suggested that the functional roles of estrogen during folliculogenesis may be regulated by SULT1E1through the metabolism of 17-beta estradiol and that the expression of SULT1E1 gene may be under the control of the levels of estrogen.