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61.
Prolonged root hypoxia effects on enzymes involved in nitrogen assimilation pathway in tomato plants 总被引:1,自引:0,他引:1
In order to investigate the effects of root hypoxia (1–2% oxygen) on the nitrogen (N) metabolism of tomato plants (Solanum lycopersicum L. cv. Micro-Tom), a range of N compounds and N-assimilating enzymes were performed on roots and leaves of plants submitted to root hypoxia at the second leaf stage for three weeks. Obtained results showed that root hypoxia led to a significant decrease in dry weight (DW) production and nitrate content in roots and leaves. Conversely, shoot to root DW ratio and nitrite content were significantly increased. Contrary to that in leaves, glutamine synthetase activity was significantly enhanced in roots. The activities of nitrate and nitrite reductase were enhanced in roots as well as leaves. The higher increase in the NH4+ content and in the protease activities in roots and leaves of hypoxically treated plants coincide with a greater decrease in soluble protein contents. Taken together, these results suggest that root hypoxia leaded to higher protein degradation. The hypoxia-induced increase in the aminating glutamate dehydrogenase activity may be considered as an alternative N assimilation pathway involved in detoxifying the NH4+, accumulated under hypoxic conditions. With respect to hypoxic stress, the distinct sensitivity of the enzymes involved in N assimilation is discussed.Key words: tomato, hypoxia, nitrogen, glutamine synthetase, protease, glutamate dehydrogenase 相似文献
62.
Faouzi Sakouhi Christelle Absalon Guido Flamini Pier Luigi Cioni Habib Kallel Sadok Boukhchina 《Comptes rendus biologies》2010,333(9):642-648
The analysis of the total lipid fraction from the Sayali variety of olive oil was accomplished in the present investigation. Glyceridic, unsaponifiable and flavour fractions of the oil were isolated and identified using several analytical methods. Chromatographic techniques have proven to be suitable for these determinations, especially capillary gas chromatography. Gas chromatography coupled to mass spectrometry was successfully used to identify sterols, triterpenes alcohols, 4-monomethylsterols, aliphatic alcohols and aroma compounds in our samples. Furthermore, solid phase microextraction was used to isolate volatiles from the total lipid fraction. Results from the quantitative characterization of Sayali olive oil showed that oleic acid (77.4%) and triolein (47.4%) were the dominant glyceridic components. However, the main compounds of the unsaponifiable fraction were β-sitosterol (147.5 mg/100 g oil), 24-methylene cycloartenol (146.4 mg/100 g oil) and hexacosanol (49.3 mg/100 g oil). Moreover, results showed that the aldehydic compounds were the major flavours present in Sayali olive oil. 相似文献
63.
Boucher D Laffaire JB Jaziri F David C Biderre-Petit C Duquenne P Peyretaillade E Peyret P 《Microbial ecology》2011,62(4):868-881
Biological degreasing system is a new technology based on the degradation capabilities of microorganisms to remove oil, grease,
or lubricants from metal parts. No data is available about the potential biological health hazards in such system. Thus, a
health risk assessment linked to the bacterial populations present in this new degreasing technology is, therefore, necessary
for workers. We performed both cultural and molecular approaches in several biological degreasing systems for various industrial
contexts to investigate the composition and dynamics of bacterial populations. These biological degreasing systems did not
work with the original bacterial populations. Indeed, they were colonized by a defined and restricted group of bacteria. This
group replaced the indigenous bacterial populations known for degrading complex substrates. Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa, and Pantoea agglomerans were important members of the microflora found in most of the biological degreasing systems. These bacteria might represent
a potential health hazard for workers. 相似文献
64.
The biochemical consequences of root hypoxia have been documented in many sink organs, but not extensively in fruit. Therefore,
in the present study, the response to root hypoxia in tomato fruit (Solanum lycopersicum L.) was investigated at two developmental stages, during the cell division and the cell expansion phases. Our results showed
that in dividing fruit, root hypoxia caused an exhaustion of carbon reserves and proteins. However, ammonium and major amino
acids (glutamine, asparagine and γ–aminobutyric acid (GABA)) significantly accumulated. In expanding fruit, root hypoxia had
no effect on soluble sugar, protein and glutamine contents, whereas starch content was significantly decreased, and asparagine
and GABA contents slightly increased. Metabolite contents were well correlated with activities of the corresponding metabolising
enzymes. Contrary to nitrogen metabolising enzymes (glutamine synthetase, asparagine synthetase and glutamate decraboxylase),
the activities of enzymes involved in sugar metabolism (invertase, sucrose synthase, sucrose phosphate synthase and ADP glucose
pyrophosphorylase) were significantly reduced by root hypoxia, in diving fruit. In expanding fruit, only a slight decrease
in ADP glucose pyrophosphorylase and an increase in asparagine synthetase and glutamate decarboxylase activities were observed.
Taken together, the present data revealed that the effects of root hypoxia are more pronounced in the youngest fruits as it
is probably controlled by the relative sink strength of the fruit and by the global disturbance in plant functioning. 相似文献
65.
Leinninger GM Opland DM Jo YH Faouzi M Christensen L Cappellucci LA Rhodes CJ Gnegy ME Becker JB Pothos EN Seasholtz AF Thompson RC Myers MG 《Cell metabolism》2011,14(3):313-323
Leptin acts on leptin receptor (LepRb)-expressing neurons throughout the brain, but the roles for many populations of LepRb neurons in modulating energy balance and behavior remain unclear. We found that the majority of LepRb neurons in the lateral hypothalamic area (LHA) contain neurotensin (Nts). To investigate the physiologic role for leptin action via these LepRb(Nts) neurons, we generated mice null for LepRb specifically in Nts neurons (Nts-LepRbKO mice). Nts-LepRbKO mice demonstrate early-onset obesity, modestly increased feeding, and decreased locomotor activity. Furthermore, consistent with the connection of LepRb(Nts) neurons with local orexin (OX) neurons and the ventral tegmental area (VTA), Nts-LepRbKO mice exhibit altered regulation of OX neurons and the mesolimbic DA system. Thus, LHA LepRb(Nts) neurons mediate physiologic leptin action on OX neurons and the mesolimbic DA system, and contribute importantly to the control of energy balance. 相似文献
66.
The effects of root hypoxia on ethylene biosynthesis and perception have been documented in many vegetative organs, but not extensively in fruit. Therefore, in the present study, the effects of root hypoxia on ethylene biosynthesis and perception were investigated in tomato (Solanum lycopersicum L.) fruit at five stages of the maturation phase. Our results showed that root hypoxia do not affect ethylene biosynthesis in fruit, but stimulates its reception from other plant part, as indicated by the increase in the expression of ethylene receptors ETR 1 and 3. 相似文献
67.
Nezha Tahri Joutey Wifak Bahafid Hanane Sayel Hajar Maâtaoui Faouzi Errachidi 《Soil & Sediment Contamination》2015,24(2):129-142
Hexavalent chromium Cr(VI) is regularly introduced into the environment through diverse anthropogenic activities. It is highly toxic, mutagenic and carcinogenic, and because of its solubility in water, chromate contamination can be difficult to contain. Bacteria can reduce chromate to insoluble and less toxic trivalent chromium Cr(III), and thus increasing attention is paid to chromate bioremediation to reduce its ecotoxicological impacts. In this study, the factorial design 23 was employed to optimize critical parameters responsible for higher Cr(VI) removal by a bacterial consortium. The factors considered were pH, temperature, and inoculum size at two markedly different levels. All three dependent variables have significant effect on Cr(VI) reduction. Optimal Cr(VI) removal by the bacterial consortium occurred at pH 9, temperature 37°C, and inoculum size OD = 3. Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of 0.984, thus ensuring a satisfactory adjustment of the second-order regression model with the experimental data. In addition, the effect of bioaugmentation of Cr(VI)-polluted soil microcosms with the bacterial consortium was investigated using the best factor levels. Contaminated soil by 20 and 60 mg/Kg of Cr(VI) showed reductions of 83% and 65% of initial Cr(VI) by the bacterial consortium, suggesting that this bacterial consortium might diminish phytoavailable Cr(VI) in soil and be useful for cleaning up chromium-contaminated sites. 相似文献
68.
69.
Faouzi Baklouti Shu-Ching Huang Tom J. Vulliamy Jean Delaunay Edward J. Benz Jr. 《Genomics》1997,39(3):289
Protein 4.1 is a globular 80-kDa component of the erythrocyte membrane skeleton that enhances spectrin–actin interaction via its internal 10-kDa domain. Previous studies have shown that protein 4.1 mRNA is expressed as multiple alternatively spliced isoforms, resulting from the inclusion or exclusion of small cassette sequences called motifs. By tissue screening for protein 4.1 isoforms, we have observed new features of an already complex pattern of alternative splicing within the spectrin/actin binding domain. In particular, we found a new 51-nt exon that is present almost exclusively in muscle tissue. In addition, we have isolated multiple genomic clones spanning over 200 kb, containing the entire erythroid and nonerythroid coding sequence of the human locus. The exon/intron structure has now been characterized; with the exception of a 17-nt motif, all of the alternatively spliced motifs correspond to individual exons. The 3′-untranslated region (UTR) has also been completely sequenced using various PCR and genomic-sequencing methods. The 3′ UTR, over 3 kb, accounts for one-half of the mature mRNA. 相似文献
70.
Noizet M Harrabi F Vijayalakshmi M Galbraith D Thomas D Thomasset B 《Biotechnology journal》2008,3(3):392-402
The expression of a fusion protein formed between the avian infectious bronchitis virus M protein and the bacterial enzyme beta-glucuronidase (GUS) in plants promotes the formation of new organization of the endoplasmic reticulum in tobacco plants. This unusual organization of the membranes, never present in nontransformed plants, has been explained by the oligomerization of the GUS domains of the IBVM-GUS fusion proteins. These specific organized membranes could have broad implications for biotechnology since their formation could be used as a mechanism for retaining and accumulating resident proteins in specific and discrete membrane compartments. In this study, we have shown that the unusual organization of native membranes due to overexpression of the IBVM-GUS fusion gene in tobacco transgenic plants and calli is present at higher levels in plant cell suspensions than in plant tissues. In these cell suspensions, IBVM-GUS protein was continuously synthesized and accumulated throughout the cell culture. An enrichment of the chimeric IBVM-GUS protein corresponding to a five-fold increase in the microsomal fractions was achieved and the GUS enzyme did not show any modification on enzyme kinetics. However, the GUS activity could be differentially distributed in the fractions eluted at different pH suggesting differences in the surface topography of histidine residues for this recombinant GUS. 相似文献