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381.
Phosphoenolpyruvate carboxykinase activity decreases when Euglena gracilis Z and ZR undergo light-induced chloroplast development in batch resting medium lacking utilizable organic carbon and CO2. This enzyme is present in heterotrophically grown cells (Briand et al. 1981) and assures gluconeogenesis. It was consistently more active in strain ZR. Decreased carboxykinase activities were accompanied by parallel increases in the activities of ribulose bisphosphate carboxylase and phosphoenolpyruvate carboxylase. The rates of O2 evolution in light were much lower than those of CO2 fixed simultaneously. The incorporation of 14CO2 into early C-4 dicarboxylic acids was higher in green cells than in etiolated cells, and it was even higher in green cells assayed in light in the presence of (DCMU). A hypothesis has been proposed, according to which there is a possible cooperation of phosphoenolpyruvate carboxylase in photosynthetic CO2 fixation, especially under conditions of limiting CO2.High temperatures (34° C) depress carboxylation enzyme activities to a greater extent than that of the carboxykinase without a great effect on cellular chlorophyll content. In the presence of 25 m DCMU, however, chlorophyll accumulation is reduced without any detectable changes in enzyme activities in the Z strain. The ZR strain displayed its characteristic resistance to DCMU.Abbreviations PEP
phosphoenolpyruvate
- RuBP
ribulose bisphosphate
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
To whom all correspondence and reprint request should be addressed 相似文献
382.
Chris Ottolenghi Iraj Daizadeh Albert Ju Sophia Kossida Georges Renault Michel Jacquet Arlette Fellous Walter Gilbert Reiner Veitia 《Mammalian genome》2000,11(9):786-788
We have recently cloned the gene C14orf1, which is strongly expressed in normal testis and in several cancer cell lines and
tumors. This gene maps to 14q24.3 and is interrupted by four introns. Two of them are also represented in the open reading
frame of Schizosaccharomyces pombe in the same phase. In Arabidopsis taliana only the first of the two introns was found, in the same phase as the corresponding ones in S. pombe and human. Disruption of the ortholog in Saccharomyces cerevisiae (Yer044c) led to a severe growth defect, and C14orf1 failed to complement mutant yeast when put under the control of the
natural Yer044c promoter. Further studies are needed to understand the causes underlying the high degree of conservation of the C14orf1 genomic
structure.
Received: 7 February 2000 / Accepted: 14 April 2000 相似文献
383.
Faucher N Martres P Laroze A Pineau O Potvain F Grillot D 《Bioorganic & medicinal chemistry letters》2008,18(2):710-715
Starting from the structure of 5, a two-step strategy was applied to identify a new generation of trifluoromethane sulfonamides as potent PPARalpha agonists. Synthesis, in vitro and in vivo evaluation of the most potent compound are reported. 相似文献
384.
Cesar ET de Almeida MV Fontes AP Pereira Maia EC Garnier-Suillerot A Rúbia Costa Couri M de Castro Antunes Felício E 《Journal of inorganic biochemistry》2003,95(4):297-305
This work describes the synthesis and characterization of six new dinuclear platinum complexes having N,N'-di-(2-aminoethyl)-1,3-diamino-2-propanol, aryl substituted N-benzyl-1,4-butanediamines and N-benzyl-1,6-hexanediamines as ligands. They were prepared by the reaction of cis-[PtCl(2)(DMSO)(2)] (DMSO=dimethyl sulfoxide) with the appropriate ligand in water, except for one of them, which was prepared from K(2)PtCl(4). We also report the cytotoxic activity and cellular accumulation of three of these complexes in a human small-cell lung carcinoma cell line and its resistant subline. Resistant cells exhibited a lesser degree of cross-resistance to these compounds when compared to cisplatin. The accumulation of platinum in both cell lines followed the same pattern, i.e. approximately the same intracellular platinum concentration yielded the same cytotoxic effect independent of the nature of the platinum complex used. 相似文献
385.
Com E Evrard B Roepstorff P Aubry F Pineau C 《Molecular & cellular proteomics : MCP》2003,2(4):248-261
Despite the essential role played by spermatogonia in testicular function, little is known about these cells. To improve our understanding of their biology, our group recently identified a set of 53 spermatogonial proteins using two-dimensional (2-D) gel electrophoresis and mass spectrometry. To continue this work, we investigated a subset of the spermatogonial proteome using narrow range immobilized pH gradients to favor the detection of less abundant proteins. A 2-D reference map of spermatogonia in the pH range 4-9 was created, and protein entities fractionated in a pH 5-6 2-D gel were further processed for protein identification. A new set of 156 polypeptides was identified by peptide mass fingerprinting and tandem mass spectrometry. These polypeptides corresponded to 102 different proteins, which reflect the complexity of post-translational modifications. Seventy-nine of these proteins were identified for the first time in spermatogonia. All identified proteins were classified into functional groups. This work represents a first step toward the establishment of a systematic spermatogonia protein database. 相似文献
386.
Sophie?Dandelot Régine?Verlaque Alain?Dutartre Arlette?CazaubonEmail author 《Hydrobiologia》2005,539(1):131-136
We analyzed meta-community structure of bdelloid rotifers colonizing mosses along an 80 meter section of Rio Valnava in NW
Italy. Bdelloid rotifers are small animals living associated with a substratum; colonization in bdelloids can be produced
by active animals moving along the riverbed, or by passive dormant propagules, moved by wind. To detect which kind of colonization
might be stronger at different spatial scales, we designed a spatially nested sampling experiment at three hierarchical levels:
(1) single sample, (2) 10 communities inside each pool, (3) complete section of 10 pools. Assessing species richness and species
similarity of communities, and coherence and nestedness of bdelloid meta-communities, we found that different forces may drive
species composition at different spatial scales: at the largest scale, colonization of propagules may over-ride direct dispersal
between pools, while at the scale of the single pool, differential movements of species give a nested structure to the meta-communities.
The number of species increased as the level of analysis increased, even though this study was carried out along only a small
stream section. 相似文献
387.
Hyper- (450 mOsm/l) and hypoosmotic exposure (150 mOsm/l) of Caco-2 cells, a human intestinal epithelial cell line, induced a twofold- and a fivefold increase in the production of IL-8, a constitutively expressed cytokine, respectively. This was observed both in the presence or in the absence of added proinflammatory cytokines and the stimulatory effect of osmotic stress was additive to that induced by the cytokines. Thus, IL-8 production appeared minimal around isoosmolarity, i.e. 300 mOsm/l. Concerning the signalling pathway involved, specific inhibition of p38- or p42/44 MAP kinases decreased the IL-8 production by about 30% independently of the osmotic condition used. Inhibition of c-jun-NH2-terminal kinase (JNK) by using both dicoumarol and SP600125 totally inhibited the stimulatory effect of hypoosmolarity. Moreover, hypoosmolarity induced an about threefold increase in JNK activity demonstrating that JNK was specifically involved in the effect of hypoosmolarity on IL-8 production. This is not the case for hyperosmolarity. Such an effect of osmotic stress was not restricted to IL-8, but was also observed on the production of IL-6, a non-constitutively expressed cytokine. Again, IL-6 production appeared minimal in isoosmotic condition. Taken together, these results demonstrate that osmotic stress is a proinflammatory signal in Caco-2 cells and suggest that an osmosensor might specifically exist in intestinal epithelial cells. 相似文献
388.
Short-term binding of fibroblasts to fibronectin: optical tweezers experiments and probabilistic analysis 总被引:5,自引:0,他引:5
The biophysical properties of the interaction between fibronectin and its membrane receptor were inferred from adhesion tests
on living cells. Individual fibroblasts were maintained on fibronectin-coated glass for short time periods (1–16 s) using
optical tweezers. After contact, the trap was removed quickly, leading to either adhesion or detachment of the fibroblast.
Through a stochastic analysis of bond kinetics, we derived equations of adhesion probability versus time, which fit the experimental
data well and were used to compute association and dissociation rates (k
+=0.3–1.4 s−1 and k
off=0.05–0.25 s−1, respectively). The bond distribution is binomial, with an average bond number ≤10 at these time scales. Increasing the fibronectin
density (100–3000 molecules/μm2) raised k
+ in a diffusion-dependent manner, leaving k
off relatively unchanged. Increasing the temperature (23–37 °C) raised both k
+ and k
off, allowing calculation of the activation energy of the chemical reaction (around 20 k
B
T). Increasing the compressive force on the cell during contact (up to 60 pN) raised k
+ in a logarithmic manner, probably through an increase in the contact area, whereas k
off was unaffected. Finally, by varying the pulling force to detach the cell, we could distinguish between two adhesive regimes,
one corresponding to one bond, the other to at least two bonds. This transition occurred at a force around 20 pN, interpreted
as the strength of a single bond.
Received: 2 November 1999 / Revised version: 6 March 2000 / Accepted: 19 April 2000 相似文献
389.
390.
Jeremy F. McRae Sara R. Jaeger Christina M. Bava Michelle K. Beresford Denise Hunter Yilin Jia Sok Leang Chheang David Jin Mei Peng Joanna C. Gamble Kelly R. Atkinson Lauren G. Axten Amy G. Paisley Liam Williams Leah Tooman Benedicte Pineau Simon A. Rouse Richard D. Newcomb 《Current biology : CB》2013,23(16):1596-1600