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Constraints on modified Gauss-Bonnet gravity during big bang nucleosynthesis
Kusakabe, Motohiko,Koh, Seoktae,Kim, K. S.,Cheoun, Myung-Ki American Physical Society 2016 Physical Review D Vol.93 No.4
<P>Modified gravity is considered to be one of the possible explanations of the accelerated expansions of the present and the early universe. We study the effects of modified gravity on big bang nucleosynthesis (BBN). If the effects of modified gravity are significant during the BBN epoch, they should be observed as changes of primordial light element abundances. We assume a f(G) term with the Gauss-Bonnet term G, during the BBN epoch. A power-law relation of df/dG proportional to t(p) where t is the cosmic time was assumed for the function f(G) as an example case. We solve time evolutions of physical variables during BBN in the f(G) gravity model numerically, and we analyzed the calculated results. It is found that a proper solution for the cosmic expansion rate can be lost in some parameter region. In addition, we show that calculated results of primordial light element abundances can be significantly different from observational data. Especially, observational limits on the primordial D abundance leads to the strongest constraint on the f(G) gravity. We then derive constraints on parameters of the f(G) gravity taking into account the existence of the solution of expansion rate and final light element abundances.</P>
Phototransduction and Visual Cycle in the Ascidian Tadpole Larva
Kusakabe, Takehiro,Nakashima, Yuki,Kusakabe, Rie,Horie, Takeo,Kawakami, Isao,Yoshida, Reiko,Inada, Kyoko,Nakagawa, Masashi,Tsuda, Motoyuki Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Ascidians are lower chordates, and their tadpole-like larvae share a basic body plan with vertebrates. To study photoreceptive systems in ascidians, we have isolated and characterized cDNA clones for three opsins, five G protein ${\alpha}$ subunits (G${\alpha}$), catalytic and regulatory subunits of cGMP phosphodiesterase (PDE), and arrestin from the ascidian Ciona intestinalis tadpole larva. Ci-opsin1 and Ci-opsin2 are vertebrate-type opsins, while Ci-opsin3 is a retinal photoisomerase similar to retinochrome and mammalian RGR. Both Ci-opsin1 and arrestin are specifically localized in the photoreceptor cells of the ocellus, whereas Ci -opsin2 is not expressed in the photoreceptors, but is co-localized in another population of neurons in the brain with PDE (Ci-PDE9 and Ci-PDE$\delta$). Ci-opsin3 is present in the entire region of the brain. Though five different cDNAs encoding Ga have been cloned, no transducin-type G protein has been found yet. Interestingly, one of G${\alpha}$i isoform is conspicuously expressed in the entire region of the brain. The Ci-opsin3 gene expression was observed in a broad area of the brain vesicle as well as in the visceral ganglion. Genes encoding ascidian homologs of CRALBP and ${\beta}$-CD, whose function is required for the mammalian visual cycle, are co-expressed with Ci-opsin3 in the brain vesicle and visceral ganglion. Localization of Ci-opsin3, CRALBP, and ${\beta}$-CD in a broad area of the brain suggests that the brain of the ascidian larva has a visual cycle system similar to that of the vertebrate RPE. Based on these data, we discuss the evolution of vertebrate visual systems.
Efficient Production of Recombinant Protein in HSPs (Heat Shock Porteins) Transgenic Silkworm
Sun-Mee Hong,Jae-Man Lee,Takahiro Kusakabe 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.05
Many thousands of recombinant proteins have been successfully produced in baculovirus - infected insect cells and larvae. In this study, to improve its value and the yield of recombinant protein production, we constructed transgenic silkworm using Heat shock genes with regard to protein folding. This time, we adapted GAL4/UAS system to express at necessary time point and to carry genes for foreign protein. First, we generated two transgenic cells and silkworm lines that carried the silkworm heat shock proteins, UAS-HOP and UAS-HSC70 and UAS-HSP70 and UAS-HSP40 construct plus 3xP3-DsRED. Subsequently, to drive the GAL4 gene as activatorvector, we engineered Baculoviruses that contain the GAL4 under the P10 promoter linked to the expression cassette of interest foreign genes under the polyhedron promoter. Also, activator vector linked to the GAL4 was designed expressing 6xHis and 6xHis–GST tag. Infection of silkworm larvae with recombinant virus, His-tagged human C3d gene was more efficiently produced transgenic silkworm than that of wild-type, but not His-GST tagged. We show the possibilityin use of HSPs transgenic silkworm system by GAL4/ UAS BmNPV that can generate the efficient production of foreign protein.