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201.
Nomura R Kamei E Hotta Y Konishi M Miyake A Itoh N 《Biochemical and biophysical research communications》2006,347(1):340-346
Zebrafish pectoral fin bud formation is an excellent model for studying morphogenesis. Fibroblast growth factors (Fgfs) and sonic hedgehog (shh) are essential for pectoral fin bud formation. We found that Fgf16 was expressed in the apical ectodermal ridge (AER) of fin buds. A knockdown of Fgf16 function resulted in no fin bud outgrowth. Fgf16 is required for cell proliferation and differentiation in the mesenchyme and the AER of the fin buds, respectively. Fgf16 functions downstream of Fgf10, a mesenchymal factor, signaling to induce the expression of Fgf4 and Fgf8 in the AER. Fgf16 in the AER and shh in the zone of polarizing activity (ZPA) interact to induce and/or maintain each other's expression. These findings have revealed that Fgf16, a newly identified AER factor, plays a crucial role in pectoral fin bud outgrowth by mediating the interactions of AER-mesenchyme and AER-ZPA. 相似文献
202.
Identification of a novel galactosyl transferase involved in biosynthesis of the mycobacterial cell wall 下载免费PDF全文
Mikusová K Belánová M Korduláková J Honda K McNeil MR Mahapatra S Crick DC Brennan PJ 《Journal of bacteriology》2006,188(18):6592-6598
The possibility of the Rv3782 protein of Mycobacterium tuberculosis being a putative galactosyl transferase (GalTr) implicated in galactan synthesis arose from its similarity to the known GalTr Rv3808c, its classification as a nucleotide sugar-requiring inverting glycosyltransferase (GT-2 family), and its location within the "possible arabinogalactan biosynthetic gene cluster" of M. tuberculosis. In order to study the function of the enzyme, active membrane and cell wall fractions from Mycobacterium smegmatis containing the overexpressed Rv3782 protein were incubated with endogenous decaprenyldiphosphoryl-N-acetylglucosaminyl-rhamnose (C(50)-P-P-GlcNAc-Rha) as the primary substrate for galactan synthesis and UDP-[(14)C]galactopyranose as the immediate precursor of UDP-[(14)C]galactofuranose, the ultimate source of all of the galactofuranose (Galf) units of galactan. Obvious increased and selective synthesis of C(50)-P-P-GlcNAc-Rha-Galf-Galf, the earliest product in the pathway leading to the fully polymerized galactan, was observed, suggesting that Rv3782 encodes a GalTr involved in the first stages of galactan synthesis. Time course experiments pointed to a possible bifunctional enzyme responsible for the initial synthesis of C(50)-P-P-GlcNAc-Rha-Galf, followed by immediate conversion to C(50)-P-P-GlcNAc-Rha-Galf-Galf. Thus, Rv3782 appears to be the initiator of galactan synthesis, while Rv3808c continues with the subsequent polymerization events. 相似文献
203.
Polymerization of guaiacol by lignin-degrading manganese peroxidase from Bjerkandera adusta in aqueous organic solvents 总被引:1,自引:0,他引:1
Lignin-degrading manganese (II) peroxidase (MnP) purified from the culture of a wood-rotting basidiomycete, Bjerkandera adusta, was used in the polymerization of guaiacol. MnP was found to catalyze polymerization of guaiacol in 50% aqueous acetone,
dimethyl formamide, methanol, ethanol, dioxane, acetonitrile, ethylene glycol and methylcellosolve. Maximum yield of polyguaiacol
was achieved in 50% aqueous acetone. The weight average molecular weight (M
w) of the polymer was estimated to be 30 300 by gel permeation chromatography. However, matrix-assisted laser desorption ionization
time of flight mass spectroscopy (MALDI-TOF-MS) analysis gave a more reliable M
w of 1690. IR, 13C-NMR, MALDI-TOF-MS and pyrolysis GC-MS analyses showed the presence of C–C and C–O linkages and quinone structure in polyguaiacol.
It was also indicated that polyguaiacol has a methoxy-phenyl group as the terminal moiety. This suggests that polyguaiacol
is a branched polymer in which guaiacol units are cross-linked at the phenolic group. Thermal gravimetric and differential
scanning calorimetric analyses were also carried out. MnP also catalyzed the polymerization of o-cresol, 2,6-dimethoxyphenol and other phenolic compounds and aromatic amines. M
w of these polymers ranged from around 1000 to 1500.
Received: 2 August 1999 / Received revision: 10 December 1999 / Accepted: 4 January 2000 相似文献
204.
The changes in chlorophyll-protein complexes (CPs) in cucumbercotyledons during illumination and subsequent dark incubationwere studied by SDS-polyacrylamide gel electrophoresis. Whenetiolated cucumber seedlings were illuminated, chlorophyll wassynthesized and CPs were formed. In the early phase of greening(6 h of illumination), light-harvesting chlorophyll a/b-proteincomplex (LHCP) was the main GP. As the greening proceeded, P700chlorophyll a-protein complex (CP1) accumulated. When 6-h illuminatedseedlings were transferred to darkness, CP1 accumulated concomitantlywith a decrease in LHCP without new chlorophyll synthesis. Thechanges in the amounts of CPs in the dark became smaller withthe progress of greening and were not observed after 72 h ofillumination. These changes were confirmed by examining thechlorophyll/P700 ratio and the low temperature absorption spectrumof cotyledons. These results suggest that in the early phaseof greening, CPs were unstable and their chlorophyll moleculeseasily exchanged with those of other kinds of CPs. (Received October 14, 1982; Accepted December 1, 1982) 相似文献
205.
206.
Kumon Y Yokoyama R Haque Z Yokochi T Honda D Nakahara T 《Marine biotechnology (New York, N.Y.)》2006,8(2):170-177
We show here that a new labyrinthulid strain, L72, isolated from a fallen leaf in the Seto Inland Sea of Japan, produced only
docohexaenoic acid (DHA) among all the long-chain polyunsaturated fatty acids (LCPUFAs). The main fatty acid composition was
16:0 (28.9%), 18:0 (7.2%), 18:1 (5.7%), 18:2 (10.4%), and DHA (45.9%) without any other LCPUFA. The lipid content of the strain
was 27.4%. The cells had many lipid bodies, which were densely located in all of the cells. On phylogenetic analysis using
the 18S rDNA sequence, the strain was located in the labyrinthulids group, forming a monophyletic group with Labyrinthula sp. (strain s) and Labyrinthuila sp. (strain L59). We further tested the culture optimization of strain L72 to evaluate the ability of the strain to produce
DHA. The optimum salt concentration and the temperature of the strain were 100% of artificial seawater and 20°C. Strain L72
could grow well on soybean oil (SBO) or soybean lecithin (SBL) as the carbon source. When 20 g/l of SBL was added to the medium,
DHA production reached the maximum amount at 0.67 g/l for 14 d. The two important facts, that the strain can use SBL as the
main nutrient and contains only DHA among the LCPUFAs, will be of great advantage for industry. 相似文献
207.
When HeLa cells were incubated at 42 degrees C for 6 h with 1 mM sodium butyrate or when cells treated with 1 mM dibutyryl cyclic AMP for 24 h were incubated at 42 degrees C for 6 h, they were more thermoresistant than heated control cells without such drugs. The production of heat shock proteins was not enhanced by the drug treatment. These results suggest that there is a factor (or factors) other than heat shock proteins that accounts for the thermoresistance of HeLa cells. 相似文献
208.
Keiichi Honda Hisashi Ômura Nanao Hayashi Fumiko Abe Tatsuo Yamauchi 《Physiological Entomology》2001,26(1):6-10
Oviposition response of Ideopsis similis (L.) (Lepidoptera: Danaidae) was examined for 12 phenanthroindolizidine alkaloids present in its host plant, Tylophora tanakae (Maxim.) (Asclepiadaceae). At least five alkaloids, i.e. (+)‐isotylocrebrine (3,4,6,7‐tetramethoxyphenanthroindolizidine; l ), (+)‐3‐demethyliso‐ tylocrebrine ( 3 ), (+)‐isotylocrebrine N‐oxide ( 5 ), (+)‐6‐demethyltylocrebrine ( 8 ) and (–)‐7‐demethyltylophorine ( 10 ), were found to individually stimulate oviposition by females. Of these, compounds 1, 3 and 10 were regarded as key components most responsible for host recognition or preference. However, female egg‐laying was much higher in response to a mixture of the five alkaloids. In two‐choice bioassays, more eggs were deposited on samples comprising the five alkaloids than on samples consisting of a single alkaloid. This suggests strongly that host selection by the butterfly is mediated by the synergistic action of several phenanthroindolizidine alkaloids present in the host plant. 相似文献
209.
The triacyl anthocyanins, Leschenaultia blue anthocyanins 1 and 2 (LBAs 1 and 2) were isolated from the blue flowers of Leschenaultia R. Br. cv. Violet Lena (Goodeniaceae), in which LBA 1 was present as a dominant pigment. The structure of LBA 1 was elucidated to be delphinidin 3-O-[6-O-(malonyl)-beta-D-glucopyranoside]-7-O-[6-O-(4-O-(6-O-(4-O-(beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranosyl)-trans-caffeoyl)-beta-D-glucopyranoside] by application of chemical and spectroscopic methods. Since LAB 2 was isolated in small amount, its structure was tentatively assigned as either delphinidin 3-(malonylglucoside)-7-[(glucosyl-p-coumaroyl)-(glucosylcaffeoyl)-glucoside] or delphinidin 3-(malonyl-glucoside)-7-[(glucosyl-caffeoyl)(glucosyl-p-coumaroyl)-glucoside]. This is the first report of the occurrence of 7-polyacylated anthocyanins in the family of Goodeniaceae, although others have been found in the families of the Ranunculaceae, Campanulaceae, and Compositae. Moreover, delphinidin 3-glycoside-7-di-(glucosylcaffeoyl)-glucoside has been reported only in the flowers of Platycodon grandiflorum (Campanulaceae). From a chemotaxonomical viewpoint, the Goodeniaceae may be closely related to the Campanulaceae. 相似文献
210.
Summary. Division and partitioning of microbodies (peroxisomes) of the green alga Klebsormidium flaccidum, whose cells contain a single microbody, were investigated by electron microscopy. In interphase, the rod-shaped microbody
is present between the nucleus and the single chloroplast, oriented perpendicular to the pole-to-pole direction of the future
spindle. A centriole pair associates with one distal end of the microbody. In prophase, the microbody changes not only in
shape, from a rodlike to a branched form, but also in orientation, from perpendicular to parallel to the future pole-to-pole
direction. Duplicated centriole pairs are localized in close proximity to both distal ends of the microbody. In metaphase,
the elongated microbody flanks the open spindle, with both distal ends close to the centriole pair at either spindle pole.
The microbody further elongates in telophase and divides after septum formation (cytokinesis) has started. The association
between the centrioles and both distal ends of the microbody is maintained throughout mitosis, resulting in the distal ends
of the elongated microbody being fixed at the cellular poles. This configuration of the microbody may be favorable for faithful
transmission of the organelle during cell division. After cytokinesis is completed, the microbody reverts to the perpendicular
orientation by changing its shape. Microtubules radiating from the centrosomes flank the side of the microbody throughout
mitosis. The close association of centrosomes and microtubules with the microbody is discussed in respect to the partitioning
of the microbody in this alga.
Correspondence: H. Hashimoto, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba,
Meguro-ku, Tokyo 153-8902, Japan.
Present address: M. Honda, Department of Computational Biology, Graduate School of Frontier Sciences, University of Tokyo,
Kashiwa, Chiba, Japan. 相似文献