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411.
Kamata Yasuhiro; Kondoh Katsuhiro; Kuroiwa Tsuneyoshi; Nagata Toshiyuki 《Plant & cell physiology》1989,30(1):151-156
Tobacco mesophyll protoplasts were fused with protoplasts fromcultured cells by electric fusion. When the fusion productswere cultured for 2 d, chloroplast division was observed inthe heterokaryocytes under fluorescence microscopy after stainingwith DAPI, while such chloroplast division was not observedwhen mesophyll protoplasts alone were cultured in the same condition.
3Permanent address: Research Institute of House Food IndustryCo. Ltd., Mikuriya Sakaemachi, Higashi-Osaka-shi, Osaka, 577Japan. (Received June 21, 1988; Accepted November 22, 1988) 相似文献
412.
N. Shiojiri Tomoaki Ohta Katsuhiro Ogawa Rolf Gebhardt 《Histochemistry and cell biology》1997,108(6):489-494
Glutamine synthetase and carbamoylphosphate synthetase I expression was examined immunohistochemically in livers of spf–ash homozygous and hemizygous mice, in which one of the urea cycle enzymes (ornithine carbamoyltransferase) is deficient and
hyperammonemic disorders are obvious. In the mutant adult mouse liver, only hepatocytes lining central veins expressed glutamine
synthetase. In contrast, other hepatocytes expressed carbamoylphosphate synthetase I but not glutamine synthetase. This complementary
expression pattern is similar to that seen in wild-type mouse liver. In the liver of mutant young mice, which showed severe
retarded growth and abnormal hair and skin development, the developmental expression pattern of both enzymes was also similar
to that of the corresponding wild-type liver. However, suppression of carbamoylphosphate synthetase I expression in the pericentral
hepatocytes occurred later in the mutant than in wild-type liver. These results show that high plasma concentrations of ammonium
ions, which are one of the substrates for both the enzymes, do not change their complementary expression. Instead they support
the idea that factor(s) associated with central veins rather than humoral factors direct pericentral hepatocytes to express
glutamine synthetase and to suppress carbamoylphosphate synthetase I expression.
Accepted: 24 April 1997 相似文献
413.
Seasonal changes in the Modulus of Elasticity of living branches of three coniferous species 总被引:1,自引:0,他引:1
Siaw Onwona-Agyeman Noboru Morioka Minoru Kondo Katsuhiro Kitagawa 《Ecological Research》1995,10(2):199-206
The seasonal changes in the Modulus of Elasticity (E) of living branches ofCryptomeria japonica, Chamaecyparis obtusa andLarix leptolepis were investigated over a period of 1 year by means of a quick and non-destructive method previously introduced by the authors.
Two sample trees were used for each species and 12 branches were selected from each tree. Readings of the experiments began
in summer 1992 and were successively conducted in autumn 1992, winter 1993, spring 1993 and finally in summer 1993. Our investigations
revealed that meanE values increased in cold seasons and decreased in warm or hot seasons. Mean values ofE estimated in summer (1993) were relatively close to those estimated in summer 1992 indicating that any changes that occurred
were the direct result of the environmental factors prevailing in the intervening seasons. Extremely high meanE values were measured when the branches were in a frozen state in winter; 69.4%, 29.9% and 24.6% higher than the previous
summer for branches ofCryptomeria japonica, Chamaecyparis obtusa andLarix leptolepis, respectively. This sharp increase over the initialE values measured in summer 1992 was quite likely due to the freezing effect of rime on the branches. 相似文献
414.
415.
Novel Carotenoid-Based Biosensor for Simple Visual Detection of Arsenite: Characterization and Preliminary Evaluation for Environmental Application 总被引:1,自引:0,他引:1
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416.
Chouduri AU Mishina K Shimizu T Yamazaki M Tokumoto T Yamada S 《Archives of biochemistry and biophysics》2008,477(1):113-120
The effect of Zn2+ on three major peptidase activities of the 20S proteasome purified from Xenopus oocytes was kinetically investigated. An extremely low concentration of Zn2+ (μM range) strongly inhibited the trypsin-like activity of the 20S proteasome which was fully recoverable by the addition of EDTA. The concentration of Zn2+ for half-maximum inhibition (K0.5) was 0.60 μM which was at least 10 times lower than that of any other divalent cation tested and essentially the same as for proteasomes purified from various other organisms indicating that the inhibition is highly Zn2+-specific, reversible, and common to the proteasome regardless of its source. Zn2+ at concentrations below 100 μM instantaneously activated the chymotrypsin-like and PGPH activities, and the Zn2+ concentration for half-maximum activation was found to be 42-48 μM. These activities were time-dependently inactivated by submillimolar concentrations of Zn2+. The inactivation rates were dependent on the concentration of Zn2+ and reached a maximum of 1.60-2.40 min−1 for the three peptidase activities under the conditions used. The Zn2+ concentration for half-maximum inactivation was found to be 0.70-1.23 mM. This time-dependent inactivation was not reversed by the addition of EDTA or DTT and might not be accompanied by the dissociation of subunits of the 20S proteasome indicating that all activities are inactivated by an identical phenomenon. These results reveal the three types of effects of Zn2+ on the 20S proteasome. 相似文献
417.
Kusumoto K Uto H Hayashi K Takahama Y Nakao H Suruki R Stuver SO Ido A Tsubouchi H 《Cytokine》2006,34(1-2):24-31
We investigated the effects of polymorphisms in interleukin (IL)-10 and tumor necrosis factor (TNF)-alpha on the natural course of hepatitis C virus (HCV) infection in a community-based population in Japan. A total of 460 anti-HCV antibody seropositive individuals were classified into two groups, those who were positive or negative for HCV RNA. In HCV RNA-positive individuals with at least four annual alanine aminotransferase (ALT) measurements taken between 1993 and 2003, 74 exhibited persistently normal ALT levels, while 211 had one or more elevated ALT level tests. We examined the relationships between polymorphisms in the genes encoding IL-10 (-1082, -819, -592) or TNF-alpha (-308, -238) and HCV clearance, ALT abnormalities, or serum level of type IV collagen 7S, a marker of hepatic fibrosis. These polymorphisms were equally distributed among the patient subgroups with differential HCV RNA clearances or ALT abnormalities. Serum levels of type IV collagen 7S, however, were significantly higher in individuals with an A at position -238 or -308 in the TNF-alpha gene promoter than in individuals lacking these polymorphisms. We conclude that, while the relationships between inherited variations in IL-10 or TNF-alpha expression are not associated with alterations in HCV clearance or ALT levels, TNF-alpha polymorphisms may be associated with hepatic fibrosis. 相似文献
418.
Adenomatous polyposis coli on microtubule plus ends in cell extensions can promote microtubule net growth with or without EB1
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In interphase cells, the adenomatous polyposis coli (APC) protein accumulates on a small subset of microtubules (MTs) in cell protrusions, suggesting that APC may regulate the dynamics of these MTs. We comicroinjected a nonperturbing fluorescently labeled monoclonal antibody and labeled tubulin to simultaneously visualize dynamics of endogenous APC and MTs in living cells. MTs decorated with APC spent more time growing and had a decreased catastrophe frequency compared with non-APC-decorated MTs. Endogenous APC associated briefly with shortening MTs. To determine the relationship between APC and its binding partner EB1, we monitored EB1-green fluorescent protein and endogenous APC concomitantly in living cells. Only a small fraction of EB1 colocalized with APC at any one time. APC-deficient cells and EB1 small interfering RNA showed that EB1 and APC localized at MT ends independently. Depletion of EB1 did not change the growth-stabilizing effects of APC on MT plus ends. In addition, APC remained bound to MTs stabilized with low nocodazole, whereas EB1 did not. Thus, we demonstrate that the association of endogenous APC with MT ends correlates directly with their increased growth stability, that this can occur independently of its association with EB1, and that APC and EB1 can associate with MT plus ends by distinct mechanisms. 相似文献
419.
420.
Takashi?MasakiEmail author Katsuhiro?Osumi Kazunori?Takahashi Kazuhiko?Hozshizaki 《Plant Ecology》2005,177(2):189-199
Spatial pattern of a biotic population may change over time as its component individuals grow or die out, but whether this is the case for desert annual plants is largely unknown. Here we examined seasonal changes in spatial patterns of two annuals, Eriogonum abertianum and Haplopappus gracilis, in initial (winter) and final (summer) densities. The density was measured as the number of individuals from 384 permanent quadrats (each 0.5 m × 0.5 m) in the Chihuahuan Desert near Portal, Arizona, USA. We used three probability distributions (binomial, Poisson, and negative binomial or NB) that represent three basic spatial patterns (regular, random, and clumped) to fit the observed frequency distributions of densities of the two annuals. Both species showed clear clumped patterns as characterized by the NB and had similar inverse J-shaped frequency distribution curves in two density categories. Also, both species displayed a reduced degree of aggregation from winter to summer after the spring drought (massive die-off), as indicated by the increased k-parameter of the NB and decreased values of another NB parameter p, variance/mean ratio, Lloyd’s Index of Patchiness, and David and Moore’s Index of Clumping. Further, we hypothesized that while the NB (i.e., Poisson-logarithmic) well fits the distribution of individuals per quadrat, its components, the Poisson and logarithmic, may describe the distributions of clumps per quadrat and of individuals per clump, respectively. We thus obtained the means and variances for (1) individuals per quadrat, (2) clumps per quadrat, and (3) individuals per clump. The results showed that the decrease of the density from winter to summer for each plant resulted from the decrease of individuals per clump, rather than from the decrease of clumps per quadrat. The great similarities between the two annuals indicate that our observed temporal changes in spatial patterns may be common among desert annual plants. 相似文献