• Environmental Mutagens and Carcinogens
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• v.15 no.2
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• pp.100-105
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• 1995

The effects of DNA polymerase $\beta$ on the somatic chromosome mutations and mitotic recombinations were investigated using the transgenic Drosophila beating chimetic gene consisting of a promoter region of Drosophila actin 5C gene and rat DNA polymerase $\beta$. For detecting the somatic chromosome mutations and mitotic recombinations, the heterozygous (mwh/+) strains possessing or lacking transgene poi 13 were used. The spontaneous frequency of small mwh spots, due to deletion or nondisjunction etc., in the non-transgenic w strain and the transgenic p[pol $\beta$]-130 strain was 0.351 and 0.606, respectively. The spontaneous frequency (0.063) of large mwh spots, arises mostly from somatic recombination between the centromere and the locus mwh, in the transgenic p[pol $\beta$]-130 strain was about three times higher than that (0.021) of the non-transgenic w strain. The mutant clone frequencies of small and large mwh spots induced by N-methyl-N'-nitro-N-nitrosoguanidine and ethyl methanesulfonate in the transformant p[pol $\beta$]-130 were higher than those in the host strain w. The present results suggest that rat DNA polymerase $\beta$ participate at least in the somatic chromosome mutations and mitotic recombination processes.

• Biomolecules & Therapeutics
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• v.24 no.5
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• pp.517-522
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• 2016

${\beta}$-Arrestins are one of the protein families that interact with G protein-coupled receptors (GPCRs). The roles of ${\beta}$-arrestins are multifaceted, as they mediate different processes including receptor desensitization, endocytosis, and G protein-independent signaling. Thus, determining the GPCR regions involved in the interactions with ${\beta}$-arrestins would be a preliminary step in understanding the molecular mechanisms involved in the selective direction of each function. In the current study, we determined the roles of the N-terminus, intracellular loops, and C-terminal tail of a representative GPCR in the interaction with ${\beta}$-arrestin2. For this, we employed dopamine $D_2$ and $D_3$ receptors ($D_2R$ and $D_3R$, respectively), since they display distinct agonist-induced interactions with ${\beta}$-arrestins. Our results showed that the second and third intracellular loops of $D_2R$ are involved in the agonist-induced translocation of ${\beta}$-arrestins toward plasma membranes. In contrast, the N- and C-termini of $D_2R$ exerted negative effects on the basal interaction with ${\beta}$-arrestins.

• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.89-92
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• 2014

The Wnt/${\beta}$-catenin pathway plays important roles in a variety of biological processes, such as cell proliferation, differentiation, and organ development. Here, we used a cell-based reporter assay to identify bryostatin-1, a natural macrocyclic lactone, as an inhibitor of the Wnt/${\beta}$-catenin pathway. Bryostatin-1 suppressed ${\beta}$-catenin response transcription (CRT), which was activated by a Wnt3a-conditioned medium (Wnt3a-CM), through a decrease in the intracellular ${\beta}$-catenin protein levels, without affecting its mRNA level. In addition, pharmacological inhibition of proteasome abrogated bryostatin-1-mediated down-regulation of the ${\beta}$-catenin protein level. Our findings suggest that bryostatin-1 attenuates the Wnt/${\beta}$-catenin pathway through the promotion of proteasomal degradation of ${\beta}$-catenin.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.4
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• pp.263-274
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• 2000

Carotenoids are widely distributed natural pigments which are in an increasing demand by the market, due to their applicatins in the human food, animal feed, cosmetics, and pharmaceutical industries. Although more than 600 carotenoids have been identified in nature, only a few are industrially important (${\beta}$-carotene, astaxanthin, lutein or lycopene). To date chemical processes manufacture most of the carotenoid production, but the interest for carotenoids of biological origin is growing since theire is an increased public concern over the safety of artificial food colorants. Although much interest and effort has been devoted to the use of biological sources for industrially important carotenoids, only the production of biological ${\beta}$-carotene and astaxanthin has been reported. Among fungi, several Mucorales strains, particularly Blakeslea trispora, have been used to develop fermentation processes for the production of ${\beta}$-carotene on almost competitive cost-price levels. Similarly, the basidiomycetous yeast Xanthophyllomyces dendrorhous (the perfect state of Phaffia rhodozyma), has been proposed as a promising source of astaxanthin. This paper focuses on recent findings on the fungal pathways for carotenoid production, especially the structure and function of the genes involved in the biosynthesis of carotenoids in the Mucorales. An outlook of the possibilities of an increased industrial production of carotenoids, based on metabolic engineering of fungi for carotenoid content and composition, is also discussed.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.45-45
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• 2013

We present a test of the emission statistics of active galactic nuclei (AGN), probing the connection between the red-noise temporal power spectra and multi-modal flux distributions known from observations. We simulate AGN lightcurves under the assumption of uniform stochastic emission processes for different power-law indices of their respective power spectra. For sufficiently shallow slopes (power-law indices beta ${\leq}$ 1.0), the flux distributions (histograms) of the resulting lightcurves are approximately Gaussian. For indices corresponding to steeper slopes (beta ${\geq}$ 1.0), the flux distributions become multi-modal. This finding disagrees systematically with result of recent mm/radio observations. Accordingly, we conclude that the emission from AGN does not necessarily originate from uniform stochastic processes even if their power spectra suggest otherwise. Possible mechanisms include transitions between different activity states and/or the presence of multiple, spatially disconnected, emission regions.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.873-877
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• 2004

The relationship between the behaviors of c.c.lipase back-extraction and their percolation phenomena by using AOT reverse micellar systems (RVMS) has been studied by the addition of a small amount of additives to organic phase such as thiols and nonionic-surfactants focusing on micelle-micelle interactions. The values of ${\beta}_t$ defined by the variation of percolation processes and back-extraction behaviors of c.c.lipase have a good linear correlation. The hydrophobicity of additive molecules suppressing the cluster formation of reverse micelles (high values of ${\beta}_t$) improved the back-extraction behavior of c.c.lipase. The back-extraction fraction and its rate of c.c.clipase are increased with decreasing of the value of hydrophilic lipophilic balance (HLB) and increasing of the hydrophobicity per additive molecules added to reverse micellar systems (RVSM) in the same additives concentration.

• Journal of The Korean Astronomical Society
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• v.45 no.6
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• pp.147-156
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• 2012

We present a test of the emission statistics of active galactic nuclei (AGN), probing the connection between the red-noise temporal power spectra and multi-modal flux distributions known from observations. We simulate AGN lightcurves under the assumption of uniform stochastic emission processes for different power-law indices of their respective power spectra. For sufficiently shallow slopes (power-law indices (${\beta}{\leq}1$), the flux distributions (histograms) of the resulting lightcurves are approximately Gaussian. For indices corresponding to steeper slopes (${\beta}{\geq}1$), the flux distributions become multi-modal. This finding disagrees systematically with results of recent mm/radio observations. Accordingly, we conclude that the emission from AGN does not necessarily originate from uniform stochastic processes even if their power spectra suggest otherwise. Possible mechanisms include transitions between different activity states and/or the presence of multiple, spatially disconnected, emission regions.

• Journal of the Korean Mathematical Society
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• v.36 no.6
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• pp.1061-1073
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• 1999

Let X be a real normed linear space. Let T : D(T) ⊂ X \longrightarrow X be a uniformly continuous and ∮-strongly quasi-accretive mapping. Let {${\alpha}$n}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} , {${\beta}$n}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} be two real sequences in [0, 1] satisfying the following conditions: (ⅰ) ${\alpha}$n \longrightarrow0, ${\beta}$n \longrightarrow0, as n \longrightarrow$\infty$ (ⅱ) {{{{ SUM from { { n}=0} to inf }}}} ${\alpha}$=$\infty$. Set Sx=x-Tx for all x $\in$D(T). Assume that {u}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} and {v}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} are two sequences in D(T) satisfying {{{{ SUM from { { n}=0} to inf }}}}∥un∥<$\infty$ and vn\longrightarrow0 as n\longrightarrow$\infty$. Suppose that, for any given x0$\in$X, the Ishikawa type iteration sequence {xn}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} with errors defined by (IS)1 xn+1=(1-${\alpha}$n)xn+${\alpha}$nSyn+un, yn=(1-${\beta}$n)x+${\beta}$nSxn+vn for all n=0, 1, 2 … is well-defined. we prove that {xn}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} converges strongly to the unique zero of T if and only if {Syn}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} is bounded. Several related results deal with iterative approximations of fixed points of ∮-hemicontractions by the ishikawa iteration with errors in a normed linear space. Certain conditions on the iterative parameters {${\alpha}$n}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} , {${\beta}$n}{{{{ { }`_{n=0 } ^{$\infty$ } }}}} and t are also given which guarantee the strong convergence of the iteration processes.

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1236-1238
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• 1997

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.49-54
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• 1990

The gas-phase thermolysis reactions of ${\alpha}$- and ${\beta}$-methylated ethyl formates, Y = $CH-X-CHR_1CH_2R_2$ where X = Y = O or S and $R_1\;=\;R_2$ = H or $CH_3$, are investigated theoretically using the AM1 method. The experimental reactivity order is reproduced correctly by AM1 in all cases. The thermolysis proceeds through a six-membered cyclic transition state conforming to a retro-ene reaction, which can be conveniently interpreted using the frontier orbital theory of three-species interactions. The methyl group substituted at $C_{\alpha}\;or\;C_{\beta}$ is shown to elevate the ${\pi}$-HOMO of the donor fragment (Y = C) and depress the ${\sigma}^{\ast}$-LUMO of the acceptor fragment ($C_{\beta}$-H), increasing the nucleophilicity of Y toward ${\beta}$-hydrogen which in turn increases the reactivity. The two bond breaking processes of the $C_{\alpha}$-X and $C_{\beta}$-H bonds are concerted but not synchronous so that the reaction takes place in two stages as Taylor suggested. The initial cleavage of $C_{\alpha}$-X is of little importance but the subsequent scission of $C_{\beta}$-H occurs in a rate determining stage.