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331.
The dynamics of leaf photosynthesis in fluctuating light affects carbon gain by plants. Mesophyll conductance (gm) limits CO2 assimilation rate (A) under the steady state, but the extent of this limitation under non-steady-state conditions is unknown. In the present study, we aimed to characterize the dynamics of gm and the limitations to A imposed by gas diffusional and biochemical processes under fluctuating light. The induction responses of A, stomatal conductance (gs), gm, and the maximum rate of RuBP carboxylation (Vcmax) or electron transport (J) were investigated in Arabidopsis (Arabidopsis thaliana (L.)) and tobacco (Nicotiana tabacum L.). We first characterized gm induction after a change from darkness to light. Each limitation to A imposed by gm, gs and Vcmax or J was significant during induction, indicating that gas diffusional and biochemical processes limit photosynthesis. Initially, gs imposed the greatest limitation to A, showing the slowest response under high light after long and short periods of darkness, assuming RuBP-carboxylation limitation. However, if RuBP-regeneration limitation was assumed, then J imposed the greatest limitation. gm did not vary much following short interruptions to light. The limitation to A imposed by gm was the smallest of all the limitations for most of the induction phase. This suggests that altering induction kinetics of mesophyll conductance would have little impact on A following a change in light. To enhance the carbon gain by plants under naturally dynamic light environments, attention should therefore be focused on faster stomatal opening or activation of electron transport.Gas diffusional and biochemical processes impose significant limitations to CO2 assimilation during photosynthetic induction. 相似文献
332.
Soraya M Kazuma Marcela F Cavalcante Andréia ER Telles Andrea Queiroz Maranh?o Dulcineia SP Abdalla 《MABS-AUSTIN》2013,5(5):763-775
The in vivo modified forms of low-density lipoprotein (LDL) are important for the formation of foam cells and as mediators of the immuno-inflammatory process involved in the progression of atherosclerosis. Electronegative LDL, LDL(-), is a LDL subfraction with pro-inflammatory properties that is present in human blood. To investigate possible atheroprotective effects, an anti-LDL(-) single-chain variable fragment (scFv) was expressed in the methylotrophic yeast Pichia pastoris and its activity was evaluated in vitro against macrophages and in experimental atherosclerosis in Ldlr-/- mice. The recombinant 2C7 scFv was produced in a yield of 9.5 mg of protein/L. The specificity and affinity of purified 2C7 scFv against LDL(-) was confirmed by ELISA. To assess the activity of 2C7 scFv on foam cell formation, RAW 264.7 macrophages were exposed to LDL(-) in the presence or absence of 2C7 scFv. The 2C7 scFv inhibited the uptake of LDL(-) by macrophages in a dose-dependent manner, and internalization of LDL(-) by these cells was found to be mediated by the CD36 and CD14 receptor. In addition, compared with untreated cells, lipid accumulation in macrophages was decreased, and the expression of Cd36, Tlr-4 and Cox-2 was downregulated in macrophages treated with 2C7 scFv. Importantly, compared with untreated mice, the treatment of Ldlr-/- mice with 2C7 scFv decreased the atherosclerotic lesion area at the aortic sinus. In conclusion, our data show that 2C7 scFv inhibits foam cell formation and atherosclerotic plaque development by modulating the expression of genes relevant to atherogenesis. These results encourage further use of this antibody fragment in the development of new therapeutic strategies that neutralize the pro-atherogenic effects of LDL(-). 相似文献
333.
Toshihiko Kakiuchi Muneaki Matsuo Hiroyoshi Endo Yasuhisa Sakata Motohiro Esaki Takahiro Noda Ichiro Imamura Kazutoshi Hashiguchi Shinichi Ogata Yasuhiko Fujioka Keiichiro Hanada Kayoko Fukuda Masaya Yoshimura Tetsuro Kajiwara Kentaroh Yamamoto Daisuke Yamaguchi Hiroharu Kawakubo Taro Akashi Michihiro Sumino Keiji Matsunaga Eriko Muro Atsuo Kuwahara Kazuto Taniguchi Koji Fukuyama Akira Watanabe Ayako Takamori Masumi Okuda Kohei Yamanouchi Kazuma Fujimoto 《Helicobacter》2021,26(2):e12776
334.
Daichi Watanabe Ikuo Takahashi Naiyanate Jaroensanti-Tanaka Sho Miyazaki Kai Jiang Masaru Nakayasu Masato Wada Tadao Asami Masaharu Mizutani Kazuma Okada Masatoshi Nakajima 《The Plant journal : for cell and molecular biology》2021,105(4):1026-1034
Ectopic expression of the apple 2-oxoglutarate-dependent dioxygenase (DOX, 2ODD) gene, designated MdDOX-Co, is thought to cause the columnar shape of apple trees. However, the mechanism underlying the formation of such a unique tree shape remains unclear. To solve this problem, we demonstrated that Arabidopsis thaliana overexpressing MdDOX-Co contained reduced levels of biologically active gibberellin (GA) compared with wild type. In summary: (i) with biochemical approaches, the gene product MdDOX-Co was shown to metabolize active GA A4 (GA4) to GA58 (12-OH-GA4) in vitro. MdDOX-Co also metabolized its precursors GA12 and GA9 to GA111 (12-OH-GA12) and GA70 (12-OH-GA9), respectively; (ii) Of the three 12-OH-GAs, GA58 was still active physiologically, but not GA70 or GA111; (iii) Arabidopsis MdDOX-Co OE transformants converted exogenously applied deuterium-labeled (d2)-GA12 to d2-GA111 but not to d2-GA58, whereas transformants converted applied d2-GA9 to d2-GA58; (iv) GA111 is converted poorly to GA70 by GA 20-oxidases in vitro when GA12 is efficiently metabolized to GA9; (v) no GA58 was detected endogenously in MdDOX-Co OE transformants. Overall, we conclude that 12-hydroxylation of GA12 by MdDOX-Co prevents the biosynthesis of biologically active GAs in planta, resulting in columnar phenotypes. 相似文献
335.
Tamako Nishimura Takuya Oyama Hooi Ting Hu Toshifumi Fujioka Kyoko Hanawa-Suetsugu Kazutaka Ikeda Sohei Yamada Hiroki Kawana Daisuke Saigusa Hiroki Ikeda Rie Kurata Kayoko Oono-Yakura Manabu Kitamata Kazuki Kida Tomoya Hikita Kiyohito Mizutani Kazuma Yasuhara Yuko Mimori-Kiyosue Shiro Suetsugu 《Developmental cell》2021,56(6):842-859.e8
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336.
Masami Oguni Haruo Shinohara Tomiko Asano Kanefusa Kato Tomoichi Setogawa 《Histochemistry and cell biology》1996,106(2):235-240
The distribution and the levels of Gi1 (plus Gi3), Gi2, and G0 in rat retina were studied immunohistochemically and immunochemically during development. At embryonic day (E) 15, Gi1α/Gi3α was observed in the inner layer of the neural retina, the future nerve fiber layer (NFL), while Gi2α was observed both in the inner and outer layers of the neural retina. No immunoreactivity for G0α was observed. At E18, Gi1α/Gi3α and Gi2α appeared in the inner plexiform layer (IPL), while G0α was faintly immunoreactive only in the NFL. At birth, Gi2α/Gi3α and G0α appeared in the ganglion cell layer. Gi2α was intensely immunoreactive in the NFL and IPL. At postnatal day (P) 10, the inner portions of the retina, from the NFL
to the outer plexiform layer, were immunoreactive to Gi1α/Gi3α, Gi2α, and G0α. Gi1α/Gi3α and G0α were distributed characteristically in a laminated pattern in the IPL, but Gi2α was present homogeneously in the IPL. At P12, Gi2α appeared in the outer nuclear layer. As the postnatal days advanced, the laminated pattern of immunoreactivity to G0α in the IPL became diffuse, but immunoreactivity to Gi1α/Gi3α remained. The results of enzyme immunoassays showed that the concentration of G0α increased rapidly from P10 to P15 and reached almost the adult level at P20–P30, while Gi2α decreased until P15 and was almost constant thereafter. These results showed that the distribution of Gi1α/Gi3α, Gi2α, and G0α differs during development, suggesting that each G protein in the developing retina has a unique function. 相似文献