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61.
Two novel decarboxylase genes play a key role in the stereospecific catabolism of dehydrodiconiferyl alcohol in Sphingobium sp. strain SYK‐6 下载免费PDF全文
Sphingobium sp. strain SYK‐6 is able to use a phenylcoumaran‐type biaryl, dehydrodiconiferyl alcohol (DCA), as a sole source of carbon and energy. In SYK‐6 cells, the alcohol group of the B‐ring side chain of DCA was first oxidized to the carboxyl group, and then the alcohol group of the A‐ring side chain was oxidized to generate 5‐(2‐carboxyvinyl)‐2‐(4‐hydroxy‐3‐methoxyphenyl)‐7‐methoxy‐2,3‐dihydrobenzofuran‐3‐carboxylate (DCA‐CC). We identified phcF, phcG and phcH, which conferred the ability to convert DCA‐CC into 3‐(4‐hydroxy‐3‐(4‐hydroxy‐3‐methoxystyryl)‐5‐methoxyphenyl)acrylate (DCA‐S) in a host strain. These genes exhibited no significant sequence similarity with known enzyme genes, whereas phcF and phcG, which contain a DUF3237 domain of unknown function, showed 32% amino acid sequence identity with each other. The DCA‐CC conversion activities were markedly decreased by disruption of phcF and phcG, indicating that phcF and phcG play dominant roles in the conversion of DCA‐CC. Purified PhcF and PhcG catalysed the decarboxylation of the A‐ring side chain of DCA‐CC, producing DCA‐S, and showed enantiospecificity towards (+)‐ and (–)‐DCA‐CC respectively. PhcF and PhcG formed homotrimers, and their Km for DCA‐CC were determined to be 84 μM and 103 μM, and Vmax were 307 μmol?min?1?mg?1 and 137 μmol?min?1?mg?1 respectively. In conclusion, PhcF and PhcG are enantiospecific decarboxylases involved in phenylcoumaran catabolism. 相似文献
62.
The hairy roots of horse-radish (Armoracia rusticana
Gaert., Mey. et Scherb.) were found to contain spectrophotometrically
active phytochrome. The absorption maxima of the red-absorbing and the far
red-absorbing forms of phytochrome were the same as those of phytochrome I
in etiolated tissues and of purified phytochrome A. Red light dramatically
decreased the concentration of phytochrome in the hairy roots. The
phytochrome was concentrated at the proximal ends of hairy roots and the
concentration of phytochrome at each position in hairy roots was
quantitatively correlated with the frequency of the light-induced formation
of adventitious shoots at the same position. The level of phytochrome
reflected the duration of culture in darkness. The increase in the
concentration of phytochrome with time in darkness was positively
correlated with the frequency of light-induced formation of adventitious
shoots. The involvement of phytochromes A and B in the induction by light
of budding of adventitious shoots from horse-radish hairy roots is
discussed on the basis of the newly revealed correlations and earlier
results. 相似文献
63.
64.
Naoki Watanabe Hiroshi Neda Yoshiki Ohtusuka Hisao Sone Naofumi Yamauchi Masahiro Maeda Hiroshi Kuriyama Yoshiro Niitsu 《Cancer immunology, immunotherapy : CII》1989,28(3):157-163
Summary Several aspects of the activity and effects of tumor necrosis factor (TNF) were investigated to gain further insight into its cytotoxic mechanism. The relation between number of TNF receptors and TNF susceptibility of both tumor cells and normal cells was studied, utilizing a specific binding assay. Among the tumor cells, a fairly close correlation (r=0.855) was observed between receptor number and sensitivity to TNF. No cytotoxic effect by TNF was observed on any of the normal cells tested, even though TNF receptors were shown to be present, and cell proliferation was apparently stimulated by TNF in some cases. TNF internalization and intracellular distribution were studied by pulse-labelling and Percoll density gradient centrifugation. In L-M (murine tumorigenic fibroblasts, highly sensitive to TNF cytotoxicity) cells and HEL (human embryonic lung cells, non-sensitive to TNF cytotoxicity) cells, receptor-bound 125I-labelled recombinant human TNF was rapidly internalized and delivered to lysosomes within 15–30 min, and this was followed by degradation and release into the culture medium. The presence of either a cytoskeletal disrupting agent or a lysosomotropic agent was observed to inhibit the cytotoxic effect of TNF, thus also indicating that TNF internalization, followed by delivery to lysosomes, is essential in the cytolytic mechanism of TNF.As observed by [3H]uridine incorporation, TNF did not affect RNA synthesis in L-R cells (TNF-resistant cell lines derived from L-M cells) and HEL cells, but markedly stimulated (by 3.5 times) RNA synthesis in L-M cells. 相似文献
65.
Naofumi Nakagawa 《Primates; journal of primatology》1989,30(1):27-34
A preliminary study was carried out on the feeding ecology of patas monkeys in the rainy season in Cameroon. Their daily activity
rhythm revealed two active peaks. The proportion of time spent on feeding with respect to waking time was 30%. Patas monkeys
largely depended on the flowers and buds of herbaceous plants and the larvae of insects for their diet as they ranged widely.
Patas monkeys spent more time in feeding and travelled for a longer distance per day than the sympatric primate species, the
tantalus monkey. It is considered that these findings reflected the large amount of food requirement due to the large body
size, as well as the low density and high degree of dispersal of their food. 相似文献
66.
William S. Modi Michael Dean Hector N. Seuanez Naofumi Mukaida Kouji Matsushima Stephen J. O'Brien 《Human genetics》1990,84(2):185-187
Summary Monocyte-derived neutrophil chemotactic factor (MDNCF/IL-8, suggested gene symbol IL8) is a cytokine that chemoattracts and activates neutrophils. Using a panel of human-rodent cell hybrids that preferentially segregate human chromosomes and in situ hybridization, the MDNCF/IL-8 gene was placed on the human gene map at position 4q12-q21. This is the same location where at least three other members (platelet factor 4, melanoma growth stimulatory activity, and interferon- induced factor) of the platelet factor 4 gene superfamily reside. In addition, a restriction fragment length polymorphism was identified using MDNCF as a probe in screening genomic DNA digested with HindIII from unrelated individuals.On leave from Genetics Section, Instituto Nacional do Cancer (RJ)/ Department of Genetics, Universidade Federal do Rio de Janeiro, Brazil 相似文献
67.
Tokutomi Satoru; Inoue Yasunori; Sato Naoki; Yamamoto Kotaro T.; Furuya Masaki 《Plant & cell physiology》1986,27(5):765-773
Absorption spectra of pea 114 and 121 kDa phytochromes weremeasured at pH 6.8, 7.8 and 8.8 using a custom-made transientmultichannel spectrum analyzer. The absorption spectra of 114kDa phytochrome as PR and PFR were least affected by mediumpH. The absorption spectra at photostationary state under redlight, however, were different under the three different pHconditions, and were different from those obtained 55 s afterred-light irradiation, owing to rapid pH-dependent absorbanceincrease in both red and far-red regions in the dark. In contrast,the absorption spectra of 121 kDa phytochrome were significantlyless affected by medium pH. The absorption spectra measuredat the photostationary state showed a lower PFR peak at higherpH. The absorption spectra obtained 55 s after the irradiationwere similar under the three pH conditions since the rapid absorbanceincrease in the far-red region in the dark was small. Possibleaccumulation of 114 kDa phytochrome population(s) with low absorbanceat red-light-induced photostationary state at pH 8.8, and theprotective role of the 7 kDa polypeptide at the amino terminusagainst the pH effect in 121 kDa phytochrome are discussed. (Received February 1, 1986; Accepted April 1, 1986) 相似文献
68.
Acetylcholine (ACh) is secreted from cholinergic neurons in the basal forebrain to regions throughout the cerebral cortex, including the primary visual cortex (V1), and influences neuronal activities across all six layers via a form of diffuse extrasynaptic modulation termed volume transmission. To understand this effect in V1, we performed extracellular multi-point recordings of neuronal responses to drifting sinusoidal grating stimuli from the cortical layers of V1 in anesthetized rats and examined the modulatory effects of topically administered ACh. ACh facilitated or suppressed the visual responses of individual cells with a laminar bias: response suppression prevailed in layers 2/3, whereas response facilitation prevailed in layer 5. ACh effects on the stimulus contrast-response function showed that ACh changes the response gain upward or downward in facilitated or suppressed cells, respectively. Next, ACh effects on the signal-to-noise (S/N) ratio and the grating-phase information were tested. The grating-phase information was calculated as the F1/F0 ratio, which represents the amount of temporal response modulation at the fundamental frequency (F1) of a drifting grating relative to the mean evoked response (F0). In facilitated cells, ACh improved the S/N ratio, while in suppressed cells it enhanced the F1/F0 ratio without any concurrent reduction in the S/N ratio. These effects were predominantly observed in regular-spiking cells, but not in fast-spiking cells. Electrophysiological and histological findings suggest that ACh promotes the signaling of grating-phase information to higher-order areas by a suppressive effect on supragranular layers and enhances feedback signals with a high S/N ratio to subcortical areas by a facilitatory effect on infragranular layers. Thus, ACh distinctly and finely controls visual information processing in a manner that is specific for the modulation and cell type and is also laminar dependent. 相似文献
69.
70.
Yuen-Ling Chan M. Scott Brown Daoming Qin Naofumi Handa Douglas K. Bishop 《The Journal of biological chemistry》2014,289(26):18076-18086