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排序方式: 共有450条查询结果,搜索用时 15 毫秒
321.
Esposito S Guerriero G Vona V Di Martino Rigano V Carfagna S Rigano C 《Journal of experimental botany》2005,56(409):55-64
In barley (Hordeum vulgare L. var. Nure), glutamate synthesis and the production of reducing power by the oxidative pentose phosphate pathway (OPPP) are strictly correlated biochemical processes. NADH-GOGAT was the major root isoform, whose activity increased on a medium supplied with NH4+ or NO3-; by contrast, no noticeable variations could be observed in the leaves of plants supplied with nitrogen. In the leaves, the major isoform is Fd-GOGAT, whose activity increased under nitrogen feeding. G6PDH activity increased in the roots supplied with nitrogen; no variations were observed in the leaves. Moreover, an increase of the P2 isoform in the roots was measured, giving 13.6% G6PDH activity localized in the plastids under ammonium, and 25.2% under nitrate feeding conditions. Western blots confirmed that P2-G6PDH protein was induced in the roots by nitrogen. P1-G6PDH protein was absent in the roots and increased in the leaves by nitrogen supply to the plants. The changes measured in cytosolic G6PDH seem correlated to more general cell growth processes, and do not appear to be directly involved in glutamate synthesis. The effects of light on Fd-GOGAT is discussed, together with the possibility for P2-G6PDH to sustain nitrogen assimilation upon illumination. 相似文献
322.
Esposito C Cozzolino A Porta R Mariniello L Buommino E Morelli F Metafora V Metafora S 《European journal of cell biology》2002,81(4):185-196
SV-IV (seminal vesicle protein no. 4) is a potent immunomodulatory and anti-inflammatory secretory protein (Mr 9758) produced in large amounts by the rat seminal vesicle epithelium. Here we show that this protein possesses the ability to upregulate in J774 macrophages the expression of the gene coding for the inducible nitric oxide synthase (iNOS). The increase in NO production consequent on the marked enhancement of iNOS activity was not associated with apoptotic damage of the SV-IV-treated cells. In the same experimental model, however, LPS induced upregulation of iNOS coupled with an increase in NO production and marked apoptotic death. Differences in the ability of SV-IV and LPS to control the life/ death signal balance in target cells via trans-membrane activation of apoptotic (mediated by TNF-alpha and NO/iNOS system) and anti-apoptotic (mediated by bcl-2, c-myc, etc.) pathways are suggested to be the basis of the apoptotic fate of the experimentally treated cells. In addition, considering the important role played by NO in the process of mammalian reproduction, SV-IV may be involved in the fine tuning of NO concentration in the female genital tract mucosa via an SV-IV-mediated control of iNOS gene expression in local macrophages. 相似文献
323.
Mutations in human nuclear genes encoding for subunits of mitochondrial respiratory complex I: the NDUFS4 gene 总被引:2,自引:0,他引:2
Among the mitochondrial disorders, complex I deficiencies are encountered frequently. Although some complex I deficiencies have been associated with mitochondrial DNA mutations, in the majority of the complex I-deficient patients mutations of nuclear genes are expected. This review attempts to summarize genetic defects affecting nuclear encoded subunits of complex I reported to date focusing on those found in the NDUFS4 gene. NDUFS4 product is 18 kDa protein which appears to have a dual role in complex I, at least: cAMP-dependent phosphorylation activates the complex; non-sense mutation of NDUFS4 prevents normal assembly of a functional complex in the inner mitochondrial membrane. 相似文献
324.
Vittoria Di Martino Rigano Vincenza Vona Catello Di Martino Carmelo Rigano 《Physiologia plantarum》1986,68(1):34-38
Cyanidium caldarium (Tilden) Geitler, a non-vacuolate unicellular alga, resuspended in medium flushed with air enriched with 5% CO2 , assimilated NH4 + at high rates both in the light and in the dark. The assimilation of NO3 − , by contrast, was inhibited by 63% in the dark. In cell suspensions flushed with CO2 -free air, NH4 + assimilation decreased with time both in the light and in the dark and ceased almost completely after 90 min. The addition of CO2 completely restored the capacity of the alga to assimilate NH4 + . NO3 − assimilation, by contrast, was 33% higher in the absence of CO2 and was linear with time. It is suggested that NO3 − and NH4 + metabolism in C. caldarium are differently controlled in response to the light and carbon conditions of the cell. 相似文献
325.
Maria Rosaria Torrisi Antonio Pavan Lavinia Vittoria Lotti Claudia Zompetta Alberto Faggioni Luigi Frati 《Experimental cell research》1988,175(2):326-333
The localization of epidermal growth factor (EGF) receptors over the plasma membranes of human epidermoid carcinoma A431 cells was analyzed at the electron microscopic level using surface replica techniques and conventional thin sections, in combination with immunocytochemistry. Immunolabeling was performed using two distinct monoclonal antibodies directed against the extracellular portion of the receptor, followed by protein A-colloidal gold conjugates. Unexpectedly, with the first monoclonal antibody used, the distribution of the receptors in both unfixed and glutaraldehyde-fixed cells was clearly regionalized, showing a preferential localization of the immunolabeling at the cell periphery as well as over the areas rich in microvilli and in coated and uncoated pits. A similar pattern of distribution was observed also with the other monoclonal antibody, but only when the cells were fixed with glutaraldehyde before immunolabeling. Treatment with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate modifies this distribution, inducing a more disperse pattern. Our observations suggest that a minor group of EGF receptors, which may represent the high-affinity receptors, presents a regional distribution, similar to that described for typical recycling receptors. 相似文献
326.
327.
Carmelo Rigano Vittoria Di Martino Rigano Vincenza Vona Amodio Fuggi 《Archives of microbiology》1981,129(2):110-114
Nitrogen-limited continuous cultures of Cyanidium caldarium contained induced levels of glutamine synthetase and nitrate reductase when either nitrate or ammonia was the sole nitrogen source. Nitrate reductase occurred in a catalytically active form. In the presence of excess ammonia, glutamine synthetase and nitrate reductase were repressed, the latter enzyme completely. In the presence of excess nitrate, intermediate levels of glutamine synthetase activity occurred. Nitrate reductase was derepressed but occurred up to 60% in a catalytically inactive form.Cell suspensions of C. caldarium from nitrate- or ammonialimited cultures assimilated either ammonia or nitrate immediately when provided with these nutrients. In these types of cells, as well as in cells grown with excess nitrate, the rate of ammonia assimilation was 2.5-fold higher than the rate of nitrate assimilation. It is proposed that the reduced rate at which nitrate was assimilated as compared to ammonia might be due to regulatory mechanisms which operate at the level of nitrate reductase activity. 相似文献
328.
Vittoria Nuti Ronchi Lucia Giorgetti Mariagrazia Tonelli Guido Martini 《Plant Cell, Tissue and Organ Culture》1992,30(2):115-119
Carrot cell lines W1 and W2 express permanently in culture a meiotic-like phenotpe, with apparent pairing and chiasmata formation comparable to meiosis during carrot microsporogenesis. The variant lines also show several variants of division in relation to the presence or absence of cytokinesis, nuclear fusion or spindle disturbance.The meiotic-like divisions can also be found in the abnormal structures, which are regenerated from these spontaneous variant lines. A possible role of the chromosome reducing mechanisms on carrot embryogenesis capacity and somaclonal variability is postulated. 相似文献
329.
Vincenza Vona Vittoria Di Martino Rigano Sergio Esposito Catello Di Martino Carmelo Rigano 《Physiologia plantarum》1992,85(4):652-658
Growth, intrácellular free amino acid pools and photosynthetic and respiratory activities in nutrient sufficient cells and in N- K- and P-limited cells of Cyanidium caldarium (Tilden) Geitler, and responses to nutrient resupply were investigated. Addition of ammonium to N-limited cells and of phosphate to P-limited cells resulted in a stimulation of dark respiration and in a decrease in photosynthetic oxygen evolution. Addition of K to K-limited cells had no effect on rates of photosynthesis and respiration. Nutrient limited cells and sufficient cells exhibited different free amino acid profiles. Upon resupply of ammonium to N-limited cells levels of glutamine, citrulline, arginine, alanine, and serine increased. Also the levels of δ-aminolevulinic acid (δ-ALA) and putrescine increased notably. On adding phosphate to P-limited cells the level of glutamate decreased significantly whereas the level of alanine increased and the concentrations of other amino acids remained unaffected. On adding potassium to K-limited cells there was an increase in glutamate and citrulline concentrations, and a decrease in putrescine concentration, whereas concentrations of arginine and alanine remained at the very high levels observed already before addition. Resuspension of N- and K-limited cells in a complete growth only after 25-30h. In P-limited cells resumption of growth in complete medium occurred progressively and reached the maximum rate 30h later. P-, K- and N- limited cells resuspended into sufficient media showed different rates of ammonium and phosphate assimilation. The pattern of recovery from nutrient limitation is discussed according to the cellular role fulfilled by the nutrient which was growth rate-limiting. 相似文献
330.
Diana L. Zuluaga Vittoria Liuzzi Pasquale Luca Curci Gabriella Sonnante 《Functional & integrative genomics》2018,18(6):645-657
Nitrogen is an essential macronutrient for plant growth and reproduction. In durum wheat, an appropriate nitrogen soil availability is essential for an optimal seed development. miRNAs contribute to the environmental change adaptation of plants through the regulation of important genes involved in stress processes. In this work, nitrogen stress response was evaluated in durum wheat seedlings of Ciccio and Svevo cultivars. Eight small RNA libraries from leaves and roots of chronically stressed plants were sequenced to detect conserved and novel miRNAs. A total of 294 miRNAs were identified, 7 of which were described here for the first time. The expression level of selected miRNAs and target genes was analyzed by qPCR in seedlings subjected to chronic (Ciccio and Svevo, leaves and roots) or short-term (Svevo roots) stress conditions. Some miRNAs showed an immediate stress response, and their level of expression was either maintained or returned to a basal level during a long-term stress. Other miRNAs showed a gradual up- or downregulation during the short-term stress. The newly identified miRNA ttu-novel-106 showed an immediate strongly downregulation after nitrogen stress, which was negatively correlated with the expression of MYB-A, its putative target gene. PHO2 gene was significantly upregulated after 24–48-h stress, corresponding to a downregulation of miR399b. Ttu-miR399b putative binding sites in the 5′ UTR region of the Svevo PHO2 gene were identified in the A and B genomes. Both MYB-A and PHO2 genes were validated for their cleavage site using 5′ RACE assay. 相似文献