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621.
Two relatively rare fatty acids, γ-linolenic acid (GLA) and stearidonic acid (STA), have attracted much interest due to their nutraceutical and pharmaceutical potential. STA, in particular, has been considered a valuable alternative source for omega-3 fatty acids due to its enhanced conversion efficiency in animals to eicosapentaenoic acid when compared with the more widely consumed omega-3 fatty acid, α-linolenic acid (ALA), present in most vegetable oils. Exploiting the wealth of information currently available on in planta oil biosynthesis and coupling this information with the tool of genetic engineering it is now feasible to deliberately perturb fatty acid pools to generate unique oils in commodity crops. In an attempt to maximize the STA content of soybean oil, a borage Δ6 desaturase and an Arabidopsis Δ15 desaturase were pyramided by either sexual crossing of transgenic events, re-transformation of a Δ6 desaturase event with the Δ15 desaturase or co-transformation of both desaturases. Expression of both desaturases in this study was under the control of the seed-specific soybean β-conglycinin promoter. Soybean events that carried only the Δ15 desaturase possessed a significant elevation of ALA content, while events with both desaturases displayed a relative STA abundance greater than 29%, creating a soybean with omega-3 fatty acids representing over 60% of the fatty acid profile. Analyses of the membrane lipids in a subset of the transgenic events suggest that soybean seeds compensate for enhanced production of polyunsaturated fatty acids by increasing the relative content of palmitic acid in phosphatidylcholine and other phospholipids. 相似文献
622.
Cecile Albenne Herve Canut Georges Boudart Yu Zhang Helene San Clemente Rafael Pont-Lezica Elisabeth Jamet 《植物生理学报》2009,(5):977-989
Proteomics allows the large-scale study of protein expression either in whole organisms or in purified organelles. In particular, mass spectrometry (MS) analysis of gel-separated proteins produces data not only for protein identification, but for protein structure, location, and processing as well. An in-depth analysis was performed on MS data from etiolated hypocotyl cell wall proteomics ofArabidopsis thaliana. These analyses show that highly homologous members of multigene families can be differentiated. Two lectins presenting 93% amino acid identity were identified using peptide mass fingerprinting. Although the identification of structural proteins such as extensins or hydroxyproline/proline-rich proteins (H/PRPs) is arduous, different types of MS spectra were exploited to identify and characterize an H/PRP. Maturation events in a couple of cell wall proteins (CWPs) were analyzed using site mapping. N-glycosylation of CWPs as well as the hydroxylation or oxidation of amino acids were also explored, adding information to improve our understanding of CWP structure/function relationships. A bioinformatic tool was developed to locate by means of MS the N-terminus of mature secreted proteins and N-glycosylation. 相似文献
623.
Renato Capasso Nicola S. Iacobellis Antonio Bottalico Giacomino Randazzo 《Phytochemistry》1984,23(12):2781-2784
The structure-toxicity relationships of phomenone were studied on cuttings and seedlings of tomato, and on larvae of brine shrim. Four derivatives prepared by chemical modification of phomenone were tested in comparison with PR-toxin. The toxicity to tomato cuttings (wilting and necroses of leaflets) appeared to be dependent on the integrity of the phomenone molecule, as any structural modification markedly reduced or completely abolished its phytotoxicity. By contrast, the toxicity to tomato seedlings (growth inhibition of shoots and rootlets) and to brine shrimp (larvae mortality) suggested a role for the epoxy rings in eremophilane molecules, which was enhanced by acetylation, as demonstrated by the progressive loss of activity for the sequence PR-toxin, phomenone and 9-methoxy- 6,7-de-epoxyphomenone. 相似文献
624.
A Capasso P Cretì B De Petrocellis P P De Prisco E Parisi 《Biochemical and biophysical research communications》1988,154(2):758-764
The adenylate cyclase of the sea urchin egg is stimulated by dopamine in the presence of GTP. The enzyme activity is strongly enhanced when Gpp (NH)p is substituted for GTP, or after cholera toxin treatment. Gramine, an indolamine derivative, brings about non-competitive inhibition of the dopamine-stimulated adenylate cyclase activity. Pertussis toxin causes an attenuation of the gramine-induced inhibition of adenylate cyclase. These results show that dopamine and indolamine derivatives partecipate in the regulation of the adenylate cyclase activity of the sea urchin egg. 相似文献
625.
Rat isolated intestine incubated in Krebs solution converted exogenous [14C]-arachidonic acid into products that chromatographed with prostaglandins, leukotriene B4 and 5-hydroxy-eicosatetraenoic acid. Accumulation of these products was increased by the laxative ricinoleic acid (0.34 mM) or the calcium ionophore A23187 (7.6 microM). In the presence of the calcium antagonists TMB-8 (0.43 microM) or verapamil (0.2 microM) the mean effects of ricinoleic acid or the calcium ionophore were smaller. Stimulation of arachidonic acid metabolism by ricinoleic acid therefore seems likely to involve a calcium-dependent mechanism. 相似文献
626.
Global stability results for a generalized Lotka-Volterra system with distributed delays 总被引:3,自引:0,他引:3
The paper contains an extension of the general ODE system proposed in previous papers by the same authors, to include distributed time delays in the interaction terms. The new system describes a large class of Lotka-Volterra like population models and epidemic models with continuous time delays. Sufficient conditions for the boundedness of solutions and for the global asymptotic stability of nontrivial equilibrium solutions are given. A detailed analysis of the epidemic system is given with respect to the conditions for global stability. For a relevant subclass of these systems an existence criterion for steady states is also given.Work supported by the Special Program Control of Infectious Diseases, C.N.R. and by the M.P.I., Italy 相似文献
627.
628.
629.
F. Capasso N. Mascolo G. Autore M.R. Duraccio 《Prostaglandins & other lipid mediators》1983,26(4):557-562
The effect of aloin and 1,8 dioxyanthraquinone on the release of prostaglandin-like material (PG) from rat isolated colon has been investigated. Orally administered aloin and 1,8 dioxyanthraquinone stimulates PG production by subsequently isolated segments of colon. Indomethacin was able to prevent this increased production of PG. These results suggest that the laxative properties of aloin and 1,8 dioxyanthraquinone may depend, at least in part, on increased prostaglandin synthesis by the intestinal tissue. 相似文献
630.
Anna Marina Liberati Verena De Angelis Marco Fizzotti Monica Schippa Michela Cecchini Daniela Adiuto Francesco Di Clemente Lucia Palmisano Elisabetta Micozzi Massimo Zuccaccia Saverio Cinieri 《Cancer immunology, immunotherapy : CII》1994,38(5):323-331
The association of low doses of interleukin-2 (IL-2; 5 IU/ml) and interferon (IFN; 10 IU/ml) induced an additive or synergic stimulatory effect on natural killer (NK) activity (32%) in peripheral blood samples from hairy-cell leukemia patients, both those with active disease and those in remission. The synergic NK stimulatory effect was more commonly found in samples from patients with active disease, while the additive effect was more frequent in the patients in remission. The IL-2/IFN combination provoked a nonadditive nonsynergic NK-stimulatory effect in a further 19.8% samples. The targets of the IL-2/IFN combination were typical NK cells, as shown by the fact that there was increased cytotoxicity (synergic, additive or nonadditive nonsynergic) against the K562, but not the Daudi cell line in peripheral blood mononuclear cell samples treated with the combination of the two cytokines. When CD16+/CD56+ or CD57+/CD16+/CD56+ cells were removed, the NK-stimulatory effect was lost. The fact that the NK-cell-enhancing activity of the IL-2/IFN combination was reduced when Percoll fractions 2 and 3 were used, but still persisted in 66% of tests, may have been due to cytotoxicity being higher in the untreated fractions 2 and 3 than in the untreated unfractionated samples. One of the factors responsible for the NK-stimulatory effect appears to be the capacity of the IL-2/IFN combination to trigger an increase in IFN synthesis. If similar experiments give like results in samples from patients suffering from other B-cell lymphoproliferative, or HIV-associated disorders, all of which are characterized by a deficiency in NK activity, it should be possible to use low-dose IL-2/IFN to treat these disorders and, perhaps, residual neoplastic disease without exposing the patient to undue toxicity. Further, by testing other combinations one should be able to identify the lowest IL-2 and IFN doses that would effectively boost the additive or synergic effect in a greater number of cases. 相似文献