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71.
Kawano T Shimoda M Matsumoto H Ryuda M Tsuzuki S Hayakawa Y 《The Journal of biological chemistry》2010,285(50):38889-38897
Suitable alterations in gene expression are believed to allow animals to survive drastic changes in environmental conditions. Drosophila melanogaster larvae cease eating and exit moist food to search for dry pupation sites after the foraging stage in what is known as the wandering stage. Although the behavioral change from foraging to wandering causes desiccation stress, the mechanism by which Drosophila larvae protect themselves from desiccation remains obscure. Here, we identified a gene, CG14686 (designated as Desiccate (Desi)), whose expression was elevated during the wandering stage. The Desi expression level was reversibly decreased by transferring wandering larvae to wet conditions and increased again by transferring them to dry conditions. Elevation of Desi expression was also observed in foraging larvae when they were placed in dry conditions. Desi encoded a 261-amino acid single-pass transmembrane protein with notable motifs, such as SH2 and PDZ domain-binding motifs and a cAMP-dependent protein kinase phosphorylation motif, in the cytoplasmic region, and its expression was observed mainly in the epidermal cells of the larval integuments. Overexpression of Desi slightly increased the larval resistance to desiccation stress during the second instar. Furthermore, Desi RNAi larvae lost more weight under dry conditions, and subsequently, their mortalities significantly increased compared with control larvae. Under dry conditions, consumption of carbohydrate was much higher in Desi RNAi larvae than control larvae. Based on these results, it is reasonable to conclude that Desi contributes to the resistance of Drosophila larvae to desiccation stress. 相似文献
72.
Shimoda M Li T Pihkala JP Koni PA 《Journal of immunology (Baltimore, Md. : 1950)》2006,176(4):2122-2133
We investigated the role of B cell Ag presentation in homeostasis of the memory B cell compartment in a mouse model where a conditional allele for the beta-chain of MHC class II (MHC-II) is deleted in the vast majority of all B cells by cd19 promoter-mediated expression of Cre recombinase (IA-B mice). Upon T cell-dependent immunization, a small number of MHC-II(+) B cells in IA-B mice dramatically expanded and restored normal albeit delayed levels of germinal center (GC) B cells with an affinity-enhancing somatic mutation to Ag. IA-B mice also established normal levels of MHC-II(+) memory B cells, which, however, subsequently lost MHC-II expression by ongoing deletion of the conditional iab allele without significant loss in their number. Furthermore, in vivo Ag restimulation of MHC-II(-) memory B cells of IA-B mice failed to cause differentiation into plasma cells (PCs), even in the presence of Ag-specific CD4(+) T cells. In addition, both numbers and Ag-specific affinity of long-lived PCs during the late post-GC phase, as well as post-GC serum affinity maturation, were significantly reduced in IA-B mice. These results support a notion that MHC-II-dependent T cell help during post-GC phase is not absolutely required for the maintenance of memory B cell frequency but is important for their differentiation into PCs and for the establishment of the long-lived PC compartment. 相似文献
73.
74.
The methanolic extract from the flowers of Tilia argentea (linden) was found to show a hepatoprotective effect against D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced liver injury in mice. By bioassay-guided separation using in vitro D-GalN-induced damage to hepatocytes, five flavonol glycosides were isolated as the hepatoprotective constituents of the methanolic extract. Tiliroside, the principal flavonol glycoside, strongly inhibited serum GPT and GOT elevations at doses of 25-100 mg/kg (p.o.) in D-GalN/LPS-treated mice. By comparing the inhibitory effects of tiliroside with those of its components alone, the kaempferol 3-O-beta-D-glucopyranoside moiety was found to be essential for the activity, and its effect was suggested to depend on the inhibition of tumor necrosis factor-alpha (TNF-alpha) production, decreased sensitivity of hepatocytes to TNF-alpha, and on the protection of hepatocytes against D-GalN. 相似文献
75.
Ozaki S Imai H Iwakiri T Sato T Shimoda K Nakayama T Hamada H 《Biotechnology letters》2012,34(3):475-481
A glucosyltransferase (GT) of Phytolacca americana (PaGT3) was expressed in Escherichia coli and purified for the synthesis of two O-β-glucoside products of trans-resveratrol. The reaction was moderately regioselective with a ratio of 4′-O-β-glucoside: 3-O-β-glucoside at 10:3. We used not only the purified enzyme but also the E. coli cells containing the PaGT3 gene for the synthesis of glycoconjugates. E. coli cell cultures also have other advantages, such as a shorter incubation time compared with cultured plant cells, no need for
the addition of exogenous glucosyl donor compounds such as UDP-glucose, and almost complete conversion of the aglycone to
the glucoside products. Furthermore, a homology model of PaGT3 and mutagenesis studies suggested that His-20 would be a catalytically
important residue. 相似文献
76.
H Imai M Kitagawa K Ishihara N Masuoka K Shimoda N Nakajima H Hamada 《Bioscience, biotechnology, and biochemistry》2012,76(8):1552-1554
Plant-cultured cells of Catharanthus roseus converted trans-resveratrol into its 3-O-β-D-glucopyranoside, 4'-O-β-D-glucopyranoside, 3-O-(6-O-β-D-xylopyranosyl)-β-D-glucopyranoside, and 3-O-(6-O-α-L-arabinopyranosyl)-β-D-glucopyranoside. The 3-O-(6-O-β-D-xylopyranosyl)-β-D-glucopyranoside and 3-O-(6-O-α-L-arabinopyranosyl)-β-D-glucopyranoside compounds of trans-resveratrol are both new. Incubation of plant-cultured cells of Ipomoea batatas and Strophanthus gratus with trans-resveratrol gave trans-resveratrol 3-O-β-D-glucopyranoside and trans-resveratrol 4'-O-β-D-glucopyranoside. 相似文献
77.
Plants under herbivore attack emit mixtures of volatiles (herbivore-induced plant volatiles, HIPVs) that can attract predators of the herbivores. Although the composition of HIPVs should be critical for the attraction, most studies of transgenic plant-emitted volatiles have simply addressed the effect of trans-volatiles without embedding in other endogenous plant volatiles. We investigated the abilities of transgenic wishbone flower plants (Torenia hybrida and Torenia fournieri) infested with spider mites, emitting a trans-volatile ((E)-β-ocimene) in the presence or absence of endogenous volatiles (natural HIPVs and/or floral volatiles), to attract predatory mites (Phytoseiulus persimilis). In both olfactory- and glasshouse-based assays, P. persimilis females were attracted to natural HIPVs from infested wildtype (wt) plants of T. hybrida but not to those of T. fournieri. The trans-volatile enhanced the ability to attract P. persimilis only when added to an active HIPV blend from the infested transgenic T. hybrida plants, in comparison with the attraction by infested wt plants. Intriguingly, floral volatiles abolished the enhanced attractive ability of T. hybrida transformants, although floral volatiles themselves did not elicit any attraction or avoidance behavior. Predator responses to trans-volatiles were found to depend on various background volatiles (e.g. natural HIPVs and floral volatiles) endogenously emitted by the transgenic plants. 相似文献
78.
GM1 epitope tetrasaccharide was synthesized by a condensation of sialyl-alpha(2-3)-gal acceptor and gal-beta(1-3)-GalN donor in a highly efficient manner. After introduction of mercaptohexanol to the tetrasaccharide, it was coupled to maleimide-activated KLH carrier protein to give the desired GM1 epitope-KLH conjugate. 相似文献
79.
Imamura A Yoshikawa T Komori T Ando M Ando H Wakao M Suda Y Ishida H Kiso M 《Glycoconjugate journal》2008,25(3):269-278
A series of ganglioside GM1-, GM2-, and GM3-type probes, in which the ceramide portion is replaced with a glucose residue,
were systematically synthesized based on a convergent synthetic method. 相似文献
80.
Kei Shimoda Shin-ya Yamane Hidetada Hirakawa Shinji Ohta Toshifumi Hirata 《Journal of Molecular Catalysis .B, Enzymatic》2002,16(5-6):275-281
The cultured cells of Catharanthus roseus were able to convert 2-, 3-, and 4-hydroxybenzyl alcohols into their corresponding hydroxybenzyl-β-
-glucopyranosides or β-
-glucopyranosylbenzyl alcohols, and then convert 2- and 3-hydroxybenzyl-β-
-glucopyranosides into primeverosides and vicianosides. Further, the C. roseus cells were capable of hydroxylation of 2-hydroxybenzoic acid to afford 2,5-dihydroxybenzoic acid and then glucosylation of the newly introduced phenolic hydroxyl group. 相似文献