A series of E,E,E-3,5-bis(arylidene)-1-(4-arylamino-4-oxo-2-butenoyl)-4-piperidones 4 (phenylidene) and 5 (4-nitrophenylidene) were prepared in order to explore the structural features of the N-acyl group which affects the cytotoxic potency. Evaluation toward human Molt 4/C8 and CEM T-lymphocytes revealed that many of the IC(50) figures were submicromolar and lower than melphalan. Marked inhibitory potencies toward murine leukemia L1210 cells were also noted. When evaluated against a panel of human tumor cell lines, three representative compounds in series 4 displayed selective toxicity to leukemia and colon cancer cell lines and were significantly more potent than the reference drug melphalan. Molecular modeling of representative compounds in both series 4 and the analogs, in which the configuration of the olefinic double bond was changed from E to Z (series 3), revealed that the torsion angles of the arylidene aryl rings and locations of the terminal arylaminocarbonyl groups may have contributed to the greater cytotoxic properties displayed in 3. Compounds 4c (3,4-dichlorophenylamino), d (4-methylphenylamino) and 5c (3,4-dichlorophenylamino), d (4-methylphenylamino) inhibited the activity of human N-myristoyltransferase by approximately 50% at concentrations of 50-100 microM. The compounds in series 4 and 5 were well tolerated in a short-term toxicity study in mice. 相似文献
Brassinin is a plant defense metabolite with antimicrobial activity produced de novo by a variety of Brassica species in response to stress, that is, a phytoalexin. The inhibition of brassinin oxidase (BO), a brassinin-detoxifying enzyme produced by the phytopathogenic fungus Leptosphaeria maculans, is a target in our continuing search for novel crop protection agents. To probe the substrate specificity of BO, in particular the mechanism of the detoxification step, several analogues of brassinin, including functional group isosteres ((mono/dithio)carbamate, urea, and thiourea) and homologue methyl tryptaminedithiocarbamate, were investigated using fungal cultures and purified BO. It was concluded that the essential structural features of substrates of BO were: (i) an -NH at the (mono/dithio)carbamate, urea or thiourea group; (ii) a methylene bridge between indole and the functional group; (iii) a methyl or ethyl group attached to the thiol moiety of the (mono/di)thiocarbamate group. A general stepwise pathway for the oxidation of brassinin was proposed that accounts for the structural requirements of detoxification of brassinin analogues in L. maculans. All compounds that were BO substrates appeared to be oxidized in mycelial cultures to aldehydes, except for the two most polar compounds N'-(3-indolylmethyl)-N'-methylurea and methyl N'-(3-indolylmethyl)carbamate. The substrate specificity of BO suggests that selective inhibitors can be designed for the potential control of L. maculans. 相似文献
The plant hormone ethylene is involved in numerous plant processes including in vitro growth and regeneration. Manipulating
ethylene in vitro may be useful for increasing plant regeneration from cultured cells. As part of ongoing efforts to improve
plant regeneration from barley (Hordeum vulgare L.), we investigated ethylene emanation using our improved system and investigated methods of manipulating ethylene to increase
regeneration. In vitro assays of regeneration from six cultivars, involving 10 weeks of callus initiation and proliferation
followed by 8 weeks of plant regeneration, showed a correlation between regeneration and ethylene production: ethylene production
was highest from ‘Golden Promise’, the best regenerator, and lowest from ‘Morex’ and ‘DH-20’, the poorest regenerators. Increasing
ethylene production by addition of 1-aminocyclopropane 1-carboxylic acid (ACC) during weeks 8–10 increased regeneration from
Morex. In contrast, adding ACC to Golden Promise cultures during any of the tissue culture steps reduced regeneration, suggesting
that Golden Promise may produce more ethylene than needed for maximum regeneration rates. Blocking ethylene action with silver
nitrate during weeks 5–10 almost doubled the regeneration from Morex and increased the Golden Promise regeneration 1.5-fold.
Silver nitrate treatment of Golden Promise cultures during weeks 8–14 more than doubled the green plant regeneration. These
results indicate that differential ethylene production is related to regeneration in the improved barley tissue culture system.
Specific manipulations of ethylene were identified that can be used to increase the green plant regeneration from barley cultivars.
The timing of ethylene action appears to be critical for maximum regeneration. 相似文献
In response to a joint call from US’s NSF and UK’s EPSRC for applications that aim to utilize the combined computational resources
of the US and UK, three computational science groups from UCL, Tufts and Brown Universities teamed up with a middleware team
from NIU/Argonne to meet the challenge. Although the groups had three distinct codes and aims, the projects had the underlying
common feature that they were comprised of large-scale distributed applications which required high-end networking and advanced
middleware in order to be effectively deployed. For example, cross-site runs were found to be a very effective strategy to
overcome the limitations of a single resource.
The seamless federation of a grid-of-grids remains difficult. Even if interoperability at the middleware and software stack
levels were to exist, it would not guarantee that the federated grids can be utilized for large scale distributed applications.
There are important additional requirements for example, compatible and consistent usage policy, automated advanced reservations
and most important of all co-scheduling. This paper outlines the scientific motivation and describes why distributed resources
are critical for all three projects. It documents the challenges encountered in using a grid-of-grids and some of the solutions
devised in response. 相似文献
Suaeda fruticosa and S. monoica are important halophytes for ecological rehabilitation of saline lands. We report differential physio-chemical, photosynthetic, and chlorophyll fluorescence responses in these halophytes under 100 mM sodium chloride (NaCl), 50% strength (16.25 ppt) of seawater (SW)-imposed salinity, and 10% polyethylene glycol 6000 imposed osmotic stress at 380 (ambient) and 1200 (elevated) µmol mol–1 CO2 concentrations. SW salinity enhanced the growth in both species; however, compared with S. fruticosa, the S. monoica exhibited comparatively better growth and biomass accumulation under saline conditions at elevated CO2. Results demonstrated better photosynthetic performances of S. monoica under stress conditions at both levels of CO2, and this resulted in higher accumulation of carbon, nitrogen, sugar, and starch contents. S. monoica exhibited improved antenna size, electron transfer at PSII donor side, and efficient working of photosynthetic machinery at elevated CO2, which might be due to efficient upstream utilization of reducing power to fix the CO2. The δ13C results supported the operation of C4 CO2 fixation in S. monoica and C3 or intermediate pathway of CO2 fixation in S. fruticosa. Lower accumulation of reactive oxygen species, reduced membrane damage, lowered solute potential, and higher accumulation of proline and polyphenol contents indicated elevated CO2-induced abiotic stress tolerance in Suaeda. Higher activity of antioxidant enzymes in both species at both levels of CO2 help plants to combat the oxidative stress. Upregulation of NADP-dependent malic enzyme and NADP-dependent malate dehydrogenase genes indicated their role in abiotic stress tolerance as well as photosynthetic carbon (C) sequestration. Operation of C4 type CO2 fixation in S. monoica and an intermediate CO2 fixation in S. fruticosa could be the possible reason for the superior photosynthetic efficiency of S. monoica under stress conditions at elevated CO2.
DNA replication, repair, and recombination (DRRR) are the fundamental processes required for faithful transmission of genetic information within and between generations. The DRRR genes protect the cells from potential mutations and damage during the developmental phases and stress conditions. Thus, these genes indirectly regulate diverse important agronomic traits in a crop plant. A genome-wide survey of six DRRR pathway genes, namely, DNA replication, Base Excision Repair, Nucleotide Excision Repair, Homologous Recombination, Mismatch Excision Repair, and Non-Homologous End-Joining, identified 157 DRRR genes in chickpea. Phylogenetic analysis of these genes within the legume clades and model plant Arabidopsis identified 42 conserved DRRR genes exhibiting clade-specific evolutionary patterns. Integrating the gene-based association mapping with differential expression profiling identified the natural alleles of the potential DRRR genes, primarily regulating flowering and maturation time and involved in drought tolerance of chickpea. Identifying and understanding DRRR genes’ roles in regulating yield and stress tolerance traits in a vital grain legume like chickpea is requisite for its future crop improvement endeavors. Manipulation of promising functionally relevant DRRR genes will pave the way for simultaneous improvement in multiple beneficial agronomic traits in chickpea.
Molecular Biology Reports - Plant establishment, growth, development and productivity are adversely affected by abiotic stresses that are dominant characteristics of environmentally... 相似文献