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When rats received glucagon or insulin every 2 h after partial hepatectomy (Hx), hepatic putrescine content was increased above control levels at 6 and 12 h, respectively. When the two hormones were combined, the increased levels were additive. Hepatic ornithine decarboxylase activity was above control levels at 12 h after insulin treatment. Hepatic spermidine N1-acetyltransferase activity was enhanced at 6 h only when glucagon was dosed. Putrescine administration from 0 to 4 h or from 6 to 10 h increased hepatic DNA synthesis to similar levels 22 h after Hx. These results suggest that glucagon and insulin additively stimulate hepatic putrescine production after Hx. This may explain the cooperative stimulation of liver regeneration by both hormones. 相似文献
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The purpose of our investigation was to clarify the effects of agriculture on the process of loss of litter at the periphery of a farmland. This study revealed the generation process of an ecologically unusual phenomenon that is observed around cropland in semi-arid regions. We hypothesized that the vegetation around a farmland cannot supply plant litter to the ground surface because the ecological structure has been changed by agricultural activities. The study was conducted at Xilingol steppe, Xilingol League, Inner Mongolia Autonomous Region, China. Four study lines were established from the edge of an arable field to the surrounding meadow and parallel to the wind direction during the strong wind season. Key measurement for each line was set at the border between the farmland and steppe. Four study sites were set at intervals along each line. Plant litter, soil particle size distribution, plant species composition, plant volume, and species diversity were investigated. Despite using the same mowing method at the meadows of all study sites, the litter at the only periphery of the farmland completely disappeared. Soil particle size distribution in steppe, which was adjacent to the farmland, was similar to that of the farmland. Plant community structure at the periphery of the farmland was different from that of the far side from the farmland. This implies that soil scattered from the farmland affected the species composition of the steppe. Consequently, the change in plant community structure induced litter loss because of mowing. We concluded that plant litter was lost near the farmland because of the combined effects of farming and mowing. The results support our hypothesis that the vegetation around a farmland cannot supply plant litter because the ecological structure has been changed by agricultural activities. 相似文献
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Uichiro Kotera Toru Kodama Yasuji Minoda Koichi Yamada 《Bioscience, biotechnology, and biochemistry》2013,77(8):1315-1325
In the course of study on the mechanism of the tartaric acid formation from 5-ketogluconic acid, a new intermediary substance with mauve color to Abdel-Akhel and Smith’s reagent was isolated from intact cell culture liquid. The chemical structure of this substance was determined as 1,2-dihydroxyethyl hydrogen L(+) tartrate from the results of hydrolysis experiments and from the identifications of the constituents of the molecule, and named “pretaric acid.” Tartaric acid was evidently produced from pretaric acid by intact cell culture. Clearly, then, pretaric acid appears to be an intermediate in the formation of tartaric acid from 5-ketogluconic acid. The authors assumed that in the formation of pretaric acid from 5-ketogluconic acid, a Baeyer-Villiger type oxidation occurred. 相似文献
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M Ogata S Sato H Sano T Hamaoka H Doi K Nakanishi Y Asano T Itoh H Fujiwara 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(8):2675-2682
A recently established thymic stroma-derived cell line (TSCL) supported the growth of the interleukin (IL) 2-dependent, antigen-specific helper T cell (Th) clone, 9-16, without requirement for IL-2 and antigen, and such growth was substituted by a factor produced into cultures by this established TSCL. This substance, thymic stroma-derived T cell-growth factor (TSTGF), was capable of inducing the proliferation of various Th clones including 9-16 Th clone, but not of cytotoxic T cell clones. TSTGF-induced growth promotion was obtained in a dose-dependent fashion and in maintaining antigen specificity of Th clones. The culture supernatant from the TSCL did not contain detectable level of IL-1, IL-2, IL-3, IL-4, or interferon activity. The proliferation of 9-16 Th clone was stimulated by recombinant IL-2 and IL-4 as well as TSTGF, but not by IL-1, IL-3, or interferons. However, the proliferation of this Th clone by IL-2 or IL-4 was almost completely inhibited by anti-IL-2 receptor or anti-IL-4 monoclonal antibody, respectively, whereas TSTGF-induced growth of 9-16 Th clones was not affected by either type of antibody, demonstrating that TSTGF is functionally distinct from IL-2 and IL-4. In addition, TSTGF activity was also obtained from the culture supernatant of the primary thymic explant, which was freshly prepared. These results indicate that the primary thymic explant as well as an established TSCL produce factors capable of promoting the growth of helper but not cytotoxic type of T cells in the absence of T cell growth factors thus far defined. 相似文献
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cDNA structure of murine C4b-binding protein, a regulatory component of the serum complement system 总被引:5,自引:0,他引:5
A cDNA library representing total poly(A+) RNA from the livers of male B10.WR mice was screened with a 1097 base pair (bp) probe obtained from a partial human C4b-binding protein (C4BP) cDNA clone. Two cDNA clones were isolated, the largest of which was sequenced and found to be 1889 bp in length exclusive of the poly(A) tail. The predicted mouse C4BP polypeptide chain encoded by 1239 bp is 413 amino acid residues in length and has a calculated molecular weight of 45,281. The 370-nucleotide sequence upstream from the codon for the predicted amino terminus contains two possible in-phase translational start signals which yield leader sequences of 56 and 13 amino acid residues, respectively. The 3'-untranslated region is 277 bp long, and there are two potential overlapping poly(A) recognition signals, AATTAA and ATTAAAA, located 26 and 25 bp, respectively, upstream from the poly(A) tail; these are preceded by five other potential polyadenylation signals. Beginning at the amino terminus and continuing through to residue 358, there are six contiguous regions of internal homology, each about 60 amino acids in length. The carboxy-terminal 55 amino acid sequence shares no homology with the repeating units. Extensive homology was found with human C4BP at the amino acid level (61%) as well as at the nucleotide level for both the coding and 3'-untranslated regions. Significant differences, however, were observed between mouse and human C4BP.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Toru Kimura Tsuneaki Asai Mutsuo Imai Mituru Takanami 《Molecular & general genetics : MGG》1989,219(1-2):69-74
Summary Two-dimensional gel electrophoresis, at high and low temperatures, and gel mobilities of circularly permuted DNA segments showed a large bending locus about 50 bp downstream from the right border of the 245 by oriC box, a minimal essential region of autonomous replication on the Escherichia coli chromosome. Bending was strongly enhanced by Dam methylation. In DNA from a Dam– strain, the mobility anomaly arising from altered conformation was much reduced, but was raised to the original level by methylation in vivo or in vitro. Enhancement of the mobility anomaly was also observed by hybrid formation of the Dam– strand with the Dam+ strand. Near the bending center, GATC, the target of Dam methylase, occurs seven times arranged essentially on the same face of the helix with 10.5 by per turn. We concluded that small bends at each Dam site added up to the large bending detectable by gel electrophoresis. 相似文献
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Fusae Shimizu Mari Ogata Tatsuhiko Yagi Sadao Wakabayashi Hiroshi Matsubara 《Biochimie》1989,71(11-12)
Rubredoxin was purified from Desulfovibrio vulgaris Miyazaki. It was sequenced and some of its properties determined. Rubredoxin is composed of 52 amino acids. It is highly homologous to that from D. vulgaris Hildenborough. Its N-methionyl residue is partially formalated. The millimolar absorption coefficients of the rubredoxin at 489 nm and 280 are 8.1 and 18.5, respectively, and the standard redox potential is +5 mB, which is slightly higher than those of other rubredoxins. Rubredoxin, as well as cytochrome c-553, was reduced with lactate by the action of lactate dehydrogenase of this organism, and the rection was stimulated with 2-methyl-1, 4-naphthoquinone. It is suggested that rubredoxin, in collaboration with membraous quinone, functions as natural electron carrier for cytoplasmic lactate dehydrogenase of this organism, whereas cytochrome c-553 plays the same role for periplasmic lactate dehydrogenase. 相似文献