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1.
Aspergillus parasiticus NRRL-2999 was inoculated into meat mixtures with curing salts and into yeast extractsucrose (YES) and sucrose-ammonium salts (SAS) broth with and without curing salts to determine if the presence of curing salts significantly affected growth and aflatoxin production by the mold. The effect of individual curing salts or curing salt mixtures on growth and toxin elaboration by the aspergillus was substrate dependent. When YES broth contained 100 ppm of NaNO2, 2% NaCl, or 1 or 2% NaCl plus 200 ppm of NaNO2 or 200 ppm of NaNO3, growth and/or aflatoxin production was depressed. Biosynthesis of aflatoxin B1 was enhanced by presence of 1 and 4% NaCl in YES broth. The SAS broth containing only NaCl or NaCl combined with nitrite or nitrate yielded less aflatoxin than did control broth or no aflatoxin at all. When compared to the control, an increase in growth and amount of aflatoxin occurred in SAS broth which contained 200 ppm of NaNO3. Sausages containing 100 and 200 ppm NaNO2 and no NaCl supported more mold growth and aflatoxin production than did control sausage with 3 % NaCl and 100 ppm of NaNO2. Addition of 2 and 3 % NaCl and no nitrite to sausage resulted in less aflatoxin than in control sausage. 相似文献
2.
When grown in vitro in a medium containing NH4NO3 as the sole source of nitrogen, seeds ro the orchid, Cattleya (C. labiata ‘Wonder’ X C. labiata ‘Treasure'), germinated readily and proceeded to form small plantlets. Development of the embryos was accompanied by an increase in their total nitrogen and a decline in the percent dry weight. Growth responses of the seedlings in other ammonium salts like (NH4)2SO4, (NH4)2HPO4, NH4Cl, ammonium acetate and ammonium oxalate were similar to that in NH4NO3. However, when grown in a medium containing NaNO3, development of the seedlings was drastically inhibited; KNO3, Ca(NO3)2, KNO2 and NaNO2 also were poor nitrogen sources. Attempts to grow the seedlings in NaNO3 by changing the pH or by addition of kinetin, molybdenum or ascorbic acid as supplements were completely unsuccessful. When seedlings growing in NH4NO3 for varying periods were transferred to NaNO3, it was found that those plants allowed to grow for 60 or more days in NH4NO3 could resume normal growth thereafter in NaNO3. Determination of the nitrate reductase activity in seedlings of different ages grown in NaNO3, after NH4NO3, showed that the ability of the seedlings to assimilate inorganic nitrogen was paralleled by the appearance of the enzyme. 相似文献
3.
Bioaccessibility measurements have the potential to improve the accuracy of risk assessments and reduce the potential costs of remediation when they reveal that the solubility of chemicals in a matrix (e.g., soil) differs markedly from that in the critical toxicity study (i.e., the key study from which a toxicological or toxicity reference value is derived). We aimed to apply this approach to a brownfield site contaminated with chromium, and found that the speciation was CrIII, using a combination of alkaline digestion/diphenylcarbazide complexation and X-ray absorption near edge structure analysis. The bioaccessibility of Cr2O3, the compound on which a reference dose for CrIII is based, was substantially lower (<0.1%) than that of the CrIII in the soils, which was a maximum of 9%, giving relative bioaccessibility values of 13,000% in soil. This shows that the reference dose is based on essentially an insoluble compound, and thus we suggest that other compounds be considered for toxicity testing and derivation of reference dose. Two possibilities are CrCl3·6H2O and KCr(SO4)2·12H2O, which have been used for derivation of ecological toxicity reference values and are soluble at a range of dosing levels in our bioaccessibility tests. 相似文献
4.
For plant salt tolerance, it is important to regulate the uptake and accumulation of Na+ ions. The yeast pmp3 mutant which lacks PMP3 gene accumulates excess Na+ ions in the cell and shows increased Na+ sensitivity. Although the function of PMP3 is not fully understood, it is proposed that PMP3 contributes to the restriction
of Na+ uptake and consequently salt tolerance in yeasts. In this paper, we have investigated whether the lack of RCI2A gene, homologous to PMP3 gene, causes a salt sensitive phenotype in Arabidopsis (Arabidopsis thaliana (L.) Heynh.) plants; and to thereby indicate the physiological role of RCI2A in higher plants. Two T-DNA insertional mutants
of RCI2A were identified. Although the growth of rci2a mutants was comparable with that of wild type under normal conditions, high NaCl treatment caused increased accumulation
of Na+ and more reduction of the growth of roots and shoots of rci2a mutants than that of wild type. Undifferentiated callus cultures regenerated from rci2a mutants also accumulated more Na+ than that from wild type under high NaCl treatment. Furthermore, when wild-type and rci2a plants were treated with NaCl, NaNO3, Na2SO4, KCl, KNO3, K2SO4 or LiCl, the rci2a mutants showed more reduction of shoot growth than wild type. Under treatments of tetramethylammonium chloride, CaCl2, MgCl2, mannitol or sorbitol, the growth reduction was comparable between wild-type and rci2a plants. These results suggested that RCI2A plays a role directly or indirectly for avoiding over-accumulation of excess Na+ and K+ ions in plants, and contributes to salt tolerance. 相似文献
5.
Abstract Puccinellia festucaeformis (Host) Parl.: germination and early growth on different salt substrates. Germination behaviour of Puccinellia festucaeformis seeds and early growth of seedlings at different experimental conditions was analysed. The following growth substrates were utilized: NaCl, KCl, KNO3, MgCl2, MgSO4, Na2SO4, NaNO3, CaCl2 at the decreasing concentrations of 0.50, 0.25, 0.12, 0.06M. Caryopses were allowed to imbibe and grow at alternating temperatures (10°-20°C or 20°-30°C) in the dark for 3 days. Seedling were grown for 15 days, at controlled light and temperature conditions, in the same nutrient substrates as those used for the germination experiments. The germination experiments showed a high tolerance to salts up to 0.25M solution and for the whole range of MgSO4 concentrations. High growth temperatures increased the depressive effects of salt concentrations. Seedling growth was highly reduced when salt concentration was higher than 0.12M. High salt tolerance - maximum shoot and root growth - was showed by seedling allowed to grow on 0.50M MgSO4. Germination and growth condition of Puccinellia festucaeformis is discussed in relation to the ecological features of this species and to its possible importance as bioindicator of MgSO4 rich natural substrates. 相似文献
6.
The effect of nitrogen and carbon sources, vitamins, antibiotics and metabolic inhibitors on growth and differentiation ofPaecilomyces viridis was investigated. Sodium nitrate,l-asparagine,l-proline and peptone were found to be suitable nitrogen sources for mycelial growth (M) in a synthetic medium with glucose.Paecilomyces viridis could also grow slowly in a synthetic medium containing benzylpenicillin or bacitracin as the only nitrogen sources and very
slowly even in a medium with polymyxin as the nitrogen source. Ammonium salts, area,l-arginine,d, l-aspartic acid andl,-serine were found to support intensive sporulation. Partially yeast-like growth (Y) was facilitated by NaNO2, (NH4)2SO4, NH4NO3, urea,d, l-alanine,l-arginine,d, l-aspartic acid,l-cysteine,l-glutamic acid andl-serine. Partially yeastlike growth could be observed in a medium with peptone and at an initial pH of 2. The following compounds
appear as suitable carbon sources for mycelial growth:d-glucose,d-galactose,d-mannose, maltose, sucrose, chitin andd-mannitol. No changes in morphology could be detected on any of the 25 used carbon sources in a synthetic medium with NaNO3. Yeast-like growth was induced by the antibiotics azalomycin F, cyanein (brefeldin A), griseofulvin and monorden (radicicol).
After removal of the antibiotics, mycelial growth was restored. Sporulation was stimulated by chloramphenicol, 2-deoxy-d-glucose, furancarboxylic acid and stipitatic acid. Deformation of phialides was observed after treatment with actinomycin
D, amphotericin B, boromycin, citrinin, cycloheximide, cytochalasin D, fungicidin and scopathricin. Microcyclic conidiation
or growth of phialides directly from conidia were induced by cycloheximide, desertomycin, ethidium bromide and 5-fluorouracil. 相似文献
7.
Triosephosphate isomerase tyrosine nitration induced by heme–NaNO2–H2O2 or peroxynitrite: Effects of different natural phenolic compounds
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Wanxia Gao Jie Zhao Hailing Li Zhonghong Gao 《Journal of biochemical and molecular toxicology》2017,31(6)
Peroxynitrite and heme peroxidases (or heme)–H2O2–NaNO2 system are the two common ways to cause protein tyrosine nitration in vitro, but the effects of antioxidants on reducing these two pathways‐induced protein nitration and oxidation are controversial. Both nitrating systems can dose‐dependently induce triosephosphate isomerase (TIM) nitration, however, heme–H2O2–NaNO2 was less destructive to protein secondary structures and led to more nitrated tyrosine residue than 3‐morpholinosydnonimine hydrochloride (SIN‐1, a peroxynitrite donor). Both of desferrioxamine and catechin could inhibit TIM nitration induced by heme–H2O2–NaNO2 and SIN‐1 and protein oxidation induced by SIN‐1, but promoted heme–H2O2–NaNO2‐induced protein oxidation. Moreover, the antagonism of natural phenolic compounds on SIN‐1‐induced tyrosine nitration was consistent with their radical scavenging ability, but no similar consensus was found in heme–H2O2–NaNO2‐induced nitration. Our results indicated that peroxynitrite and heme–H2O2–NaNO2‐induced protein nitration was different, and the later one could be a better model for anti‐nitration compounds screening. 相似文献
8.
Lee Shapiro Paul Aylett Donald Arthur Charles Eason 《New Zealand journal of zoology.》2013,40(2):108-121
ABSTRACTAcute toxicity of sodium nitrite (NaNO2) was assessed in chickens (Gallus gallus domesticus) and domestic mallard ducks (Anas platyrhynchos domestica) by oral gavage and in free-feeding trials with chickens, domestic mallard ducks, pigeons (Columba livia f. domestica), budgerigars (Melopsittacus undulates) and wētā (Family: Rhaphidophoridae). Free-feeding trials involved the presentation of toxic paste and pellet baits containing encapsulated NaNO2 developed for the control of common brushtail possums (Trichosurus vulpecula) and feral pigs (Sus scrofa). The oral gavage LD50 value for NaNO2 in solution was approximately 68.50?mg/kg (95% CI 55.00–80.00?mg/kg) for both chickens and ducks. In feeding trials, six out of 12 chickens consumed toxic paste bait and four of these birds consumed a lethal dose. When chickens consumed toxic paste bait, the LD50 value was approximately 254.6?mg/kg (95% CI 249.1–260.2?mg/kg). Of the other three species of birds presented with toxic baits only one duck consumed a lethal dose of paste bait. There was no evidence of wētā feeding on toxic baits. 相似文献
9.
Summary Osmotic and specific ion effect are the most frequently mentioned mechanisms by which saline substrates reduce plant growth.
However, the relative importance of osmotic and specific ion effect on plant growth seems to vary depending on the drought
and/or salt tolerance of the plant under study. We studied the effects of several single salts of Na+ and Ca2+−NaCl, NaNO3, Na2SO4, NaHCO3, Na2CO3, and Ca(NO3)2—on the germination and root and coleoptile growth of two wheat (Triticum aestivum L.) cultivars, TAM W-101 and Sturdy, the former being more drought tolerant than the latter. The concentrations used were:
0, 0.02, 0.04, 0.08, 0.16, and 0.32 mol L−1. Significant two- and three-way interactions were observed between cultivar, kind of salt, and salt concentration for germination,
growth of coleoptile and root, and root/coleoptile ratio. Salts differed significantly (P<0.001) in their effect on seed germination, coleoptile and root growth of both cultivars.
Germination of TAM W-101 seeds was consistently more tolerant than that of Sturdy to NaCl, CaCl2, Ca(NO3)2, and NaHCO3 salts at concentrations of 0.02, 0.04, 0.08, 0.16 mol L−1. The osmotic potential, at which the germination of wheat seeds was reduced to 50% of that of the control, was different
depending on the kind of salt used in the germination medium. NaCl at low concentrations (0.02 and 0.04 mol L−1) stimulated the germination of both wheat cultivars. At concentrations of 0.02 to 0.16 mol L−1, Ca2+ salts (CaCl2 and Ca(NO3)2) were consistently more inhibitory than the respective Na+ salts (NaCl and NaNO3) for germination of Sturdy. This did not consistently hold true for TAM W-101. Among the Na+ salts, NaCl was the least toxic and NaHCO3 and Na2CO3 were the most toxic for seed germination.
Root and coleoptile (in both wheat cultivars) differed in their response to salts. This differential response of coleoptile
and root to each salt resulted in seedlings with a wide range of root/coleoptile ratios. For example, the root/coleoptile
ratio of cultivar TAM W-101 changed from 2.09 (in the control) to 3.77, 3.19, 2.8, 2.44, 1.31, 0.32, and 0.0 when subjected
to 0.08 mol L−1 of Na2SO4, NaCl, CaCl2, NaNO3, Ca(NO3)2, NaHCO3, and Na2CO3, respectively. Na2CO3 at 0.08 mol L−1 inhibited root growth to such an extent that germinated wheat seeds contained coleoptile but no roots. The data indicate
that, apart from the clear and more toxic effects of NaHCO3 and Na2CO3 and lesser toxic effect of NaCl on germination and seedling growth, any toxicity-ranking of other salts done at a given concentration
and for a given tissue growth may not hold true for other salt concentrations, other tissues and/or other cultivars.
The more drought-tolerant TAM W-101, when compared to the less drought tolerant Sturdy, showed higher tolerance (at most concentrations)
to NaCl, CaCl2, Ca(NO3)2 and NaHCO3 during its seed germination and to Na2SO4 and CaCl2 for its root growth. This supports other reports that some drought-tolerant wheat cultivars are more tolerant to NaCl. In
contrast, the coleoptile growth of drought-sensitive Sturdy was noticeably more tolerant to NaNO3, Ca(NO3)2 and NaHCO3 than that of drought-tolerant TAM W-101. Based on the above and the different root/coleoptile ratios observed in the presence
of various salts, it is concluded that in these wheat cultivars: a) coleoptile and root tissues are differently sensitive
to various salts, and b) at the germination stage, tolerance to certain salts is higher in the more drought-tolerant cultivar. 相似文献
10.
Kaori Ohki Jonathan P. Zehr Paul G. Falkowski Yoshihiko Fujita 《Archives of microbiology》1991,156(5):335-337
The effect of various nitrogen sources on the synthesis and activity of nitrogenase was studied in the marine, non-heterocystous cyanobacterium Trichodesmium sp. NIBB1067 grown under defined culture conditions. Cells grown with N2 as the sole inorganic nitrogen source showed light-dependent nitrogenase activity (acetylene reduction). Nitrogenase activity in cells grown on N2 was not suppressed after 7 h incubation with 2 mM NaNO3 or 0.02 mM NH4Cl. However, after 3 h of exposure to 0.5 mM of urea, nitrogenase was inactivated. Cells grown in medium containing 2 mM NaNO3, 0.5 mM urea or 0.02 mM NH4Cl completely lacked the ability to reduce acetylene. Western immunoblots tested with polyclonal antisera against the Fe-protein and the Mo–Fe protein, revealed the following: (1) both the Fe-protein and the Mo–Fe protein were synthesized in cells grown with N2 as well as in cells grown with NaNO3 or low concentration of NH4Cl; (2) two bands (apparent molecular mass of 38 000 and 40 000) which cross-reacted with the antiserum to the Fe-protein, were found in nitrogen-fixing cells; (3) only one protein band, corresponding to the high molecular mass form of the Fe-protein, was found in cells grown with NaNO3 or low concentration of NH4Cl; (4) neither the Fe-protein nor the Mo–Fe protein was found in cells grown with urea; (5) the apparent molecular mass of the Fe-protein of Trichodesmium sp. NIBB1067 was about 5000 dalton higher than that of the heterocystous cyanobacterium, Anabaena cylindrica IAM-M1. 相似文献
11.
In this study, a neutrophilic, heterotrophic bacterium (strain Paddy-2) that is capable of ferrous iron [Fe(II)] oxidation coupled with nitrate (NO3?) reduction (NRFO) under anoxic conditions was isolated from paddy soil. The molecular identification by 16S rRNA gene sequencing identified the strain as Cupriavidus metallidurans. Strain Paddy-2 reduced 97.7% of NO3?and oxidized 89.7% of Fe(II) over 6?days with initial NaNO3 and FeCl2 concentrations of 9.37?mM and 4.72?mM, respectively. Acetate (5?mM) was also supplied as a carbon source and an alternative electron donor. A poorly crystalline Fe(III) mineral was the main component observed after 15?days of growth in culture, whereas lepidocrocite was detected in the X-ray diffraction spectrum after 3?months of culture. The homologous genes in electron transfer during Fe(II) oxidation (cyc1, cymA, FoxY, FoxZ, and mtoD) were also identified in the genomes of strain Paddy-2 and other reported NRFO bacteria. These genes encoding c-Cyts may play a role in electron transfer during the process of NRFO. These results provide evidence for the potential of NO3? to affect Fe(II) oxidation and biomineralization in bacterium from anoxic paddy soil. 相似文献
12.
Han Sun Lei Wang Hongyun Nie Zhenjun Diwu Maiqian Nie Bo Zhang 《Biotechnology progress》2021,37(4):e3155
Yield and cost are two major factors limiting the widespread use of rhamnolipids (RLs). In the present study, waste frying oil (WFO) was used as the sole carbon source to produce environmentally friendly RLs by Pseudomonas aeruginosa NY3. The Plackett–Burman design (PBD) and Box–Behnken design (BBD) methods were used to maximize the production yield of RL. The PBD results showed that the concentrations of NaNO3, Na2HPO4, and trace elements were the key factors affecting the yield of RL. Furthermore, the BBD results showed that at NaNO3, Na2HPO4, and trace elements concentrations were 4.95, 0.66, and 0.64 mL/L, respectively, the average RL yield reached 9.15 ± 0.52 g/L, 1.58-fold higher than that observed before optimization. Fourier transform infrared spectroscopy (FTIR) and liquid chromatography-ion trap-time of flight mass spectrometry (LCMS-IT-TOF) were used to elucidate the diversity of RL congeners. The results showed that, after optimization, the RL congener diversity increased, and the major RL constituent was converted from di-RLs (64.04%) to mono-RLs (60.44%). These results suggested that the concentrations of the components contained in the culture medium of P. aeruginosa NY3 influenced not only the yield of RL, but also its congener distribution. 相似文献
13.
不同氮源及其浓度对标志链带藻合成淀粉和油脂的影响北大核心CSCD 总被引:1,自引:0,他引:1
【目的】以标志链带藻(Desmodesmus insignis)为实验材料,研究不同氮源及其浓度对该藻生长、总脂和淀粉(碳水化合物)含量的影响,为该藻在生物能源方面的应用提供一定的理论依据。【方法】以硝酸钠、碳酸氢铵或尿素为氮源,5个氮浓度(3、6、9、12和18 mmol/L)的BG-11培养基培养标志链带藻,采用干重法测定生物质浓度、重量法测定总脂、苯酚-硫酸法测定、总碳水化合物和淀粉的含量。【结果】标志链带藻在3种氮源下均能很好的生长。最高油脂含量出现在3 mmol/L硝酸钠实验组,达到32.61%(d.w)。当18 mmol/L碳酸氢铵作为氮源时,总碳水化合物与淀粉的含量以及产率都达到最高,分别为56.54%(d.w)和55.33%(d.w)、0.24和0.23 g/(L·d)。以尿素为氮源时,其生物质浓度和各组分含量与其它氮源实验组差别不大,均有利于该藻的生长及各生化组分含量的积累。【结论】以该藻种生产生物能源的成本等综合考虑,以18 mmol/L碳酸氢铵和尿素为氮源培养标志链带藻最优。 相似文献
14.
Summary The purpose of this study was to investigate the phytotoxicity of nitrapyrin 2-chloro-6-(trichloromethyl)pyridine to sunflower
(Helianthus annuus L.) under different N regimes and to see if N forms affect the phytotoxicity of nitrapyrin. Sunflower was grown in pot culture
for 21 days and was fertilized with (NH4)2SO4, NH4NO3 and NaNO3 to provide 0, 100 and 200 ppm N and with nitrapyrin application of 0 and 20 ppm. All N-treated sunflower plants in all N
regimes and regardless of titrapyrin treatment produced more root and shoot dry weights and contained a significantly higher
N than untreated check. Nitrapyrin toxicity appeared as a curling of leaf margin and a tendril type of stem growth, the visible
toxicity symptoms decreased in the order: (NH4)2SO4>NH4NO3>NaNO3. Furthermore nitrapyrin addition suppressed sunflower growth in each N regime, the suppressing effect being greater with
(NH4)2SO4 and NH4NO3 than as with NaNO3. Although, shoot growth from plants receiving nitrapyrin was not significantly affected by any N regime, root growth of nitrapyrin-treated
plants was somewhat restricted by NH4
+−N nutrition relative to NO3
−−N nutrition. 相似文献
15.
Nyéssia Fernanda De Sousa Silva MáRcia Regina Simões Adriana Knob Sandra Schmidt De Moraes Caroline Henn Jose Luis Da ConceiçãO Silva 《Biocatalysis and Biotransformation》2016,34(3):119-127
Xylanase produced from the newly isolated Penicillium crustosum FP 11 and its potential in the prebleaching of kraft pulp were evaluated using a statistical approach. A Plackett–Burman design (PBD) was carried out to select the significant variables of the medium, these being NaNO3, KH2PO4, MgSO4, KCl, Fe2(SO4)3, yeast extract, corn stover, and initial pH, in a liquid culture under static conditions for 6 d at 28?°C. Statistical analysis with a central composite design and response surface methodology showed that 0.15% (w/v) KH2PO4, 2% (w/v) corn stover, and an initial pH of 6.0 provided the best conditions for xylanase production. Furthermore, xylanase from P. crustosum FP 11 was effective in the bleaching of Eucalyptus kraft pulp, with a significant kappa efficiency of 35.04%. Therefore, the newly isolated P. crustosum FP 11 from the Atlantic Forest biome in Brazil showed two advantages: xylanase production with agricultural residue (corn stover) as a carbon source and an improvement in the bleaching of kraft pulp. Environmental pollution could thus be minimized because of a reduction in the use of chlorine as a bleaching agent. 相似文献
16.
The paper reports stimulatory effect of nitric oxide (NO) on in vitro caulogenesis in Albizzia
lebbeck, a tree legume. Exogenously supplied NO donor, sodium nitroprusside (SNP) stimulated shoot differentiation from hypocotyl
explants of Albizzia lebbeck, excised from its in vitro seedlings. Potassium ferrocyanide, a structural analog of SNP incapable of releasing NO, did not
promote shoot organogenesis. Likewise, metabolic products of NO, NO2
− and NO3
−, provided as NaNO2 and NaNO3 did not enhance shoot differentiation. The NO scavenger, 2-(4-carboxy-phenyl)-4, 4, 5, 5-tetramethylimideazoline-1-oxyl-3-oxide
(cPTIO), supplemented along with SNP, at equimolar concentration, reversed the stimulatory effect of the latter, thus, confirming
the role of NO in promotion of in vitro caulogenesis. The transfer of explants cultured on the basal medium (BM) to the same
containing SNP and vice versa after different time intervals revealed that for its enhancing effect, SNP was required only
during the initial phase (5 days) of culture. Its presence or administration beyond 5 days neither promoted nor inhibited
the caulogenic response. 相似文献
17.
Farzana Sabir Rajender S. Sangwan Ritesh Kumar Neelam S. Sangwan 《Journal of Plant Growth Regulation》2012,31(4):537-548
In vitro-grown shoots and calli of Withania somnifera, an important medicinal plant, were exposed to various types of salts under in vitro culture conditions. Membrane permeability, lipid peroxidation, and the antioxidant system increased in shoots as well as in unorganized callus tissues under all the three concentrations of KCl, NaCl, KNO3, NaNO3, and CaCl2. The growth responses of shoots and callus cultures under various salt treatments revealed that the tissue could grow better under NaCl and KNO3 compared to other salts and the in vitro shoots appeared healthy at 50?mM concentration of NaCl and KNO3. The activity of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase, guaiacol peroxidase, lipoxygenase, polyphenol oxidase, and glutathione reductase increased under salt treatments, especially at higher concentrations. The greatest activity increase was recorded for peroxidases, whereas CAT was the least responsive. Only two isoforms, Mn-superoxide dismutase (Mn-SOD) and Fe-SOD, could be visualized in callus tissue while Cu/Zn-SOD was absent. Diaphorase 4 was totally missing in callus tissue and was detected only in shoots. Phenolics accumulated at all the concentrations of the salts tested as an induced protective response. The higher concentration of CaCl2 produced maximum increases in antioxidants and enzymatic activities compared to other salts. Thus, for W. somnifera the presence of excess calcium in the growing medium is most deleterious compared to other salts. Results also suggest that the nonenzymatic and enzymatic antioxidant systems of both the tissues played a primary role in combating the imposed salt stress. 相似文献
18.
Nutritional stress effects under different nitrogen sources on the genes in microalga Isochrysis zhangjiangensis and the assistance of Alteromonas macleodii in releasing the stress of amino acid deficiency
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The expressions of nine nitrogen assimilation‐associated genes, NRT2, NAR1, NIA2, NIR, GLN2, GLSF, GSN1, GDH, and AAT2, in the microalga Isochrysis zhangjiangensis were investigated to unveil the effects of limitations of various nitrogen sources (NaNO3, NH4Cl, NaNO2, and an amino acid mixture) on the microalgae. The results demonstrated that the NRT2, NAR1, GLN2, GSN1, and AAT2 genes were highly expressed in lipid‐rich microalgae under inorganic nitrogen‐deficient conditions and they decreased after nitrogen resupply. Significant increases in the expressions of NAR1, GLN2, and GLSF were found in nitrate‐depleted microalgae, whereas significant increases in the expressions of NRT2, NAR1, GLN2, and GSN1 were found in nitrite‐depleted microalgae. Significant increases in the expressions of only NRT2 and GSN1 were found in ammonium‐depleted microalgae (P < 0.05). Except for the NRT2, other genes were expressed at lower levels under amino acid‐deficient conditions compared with amino acid‐sufficient controls. The expression of the NIA2 gene decreased in nitrogen‐depleted microalgae regardless of the initial nitrogen source. However, the results of fatty acid analyses showed that the features of fatty acid profiles followed a similar mode, in which the percentage compositions of C16:0 and C18:1Δ9 increased in nitrogen‐depleted cells and that of C16:1Δ9, C18:3Δ9,12,15, C18:4Δ6,9,12,15, and C18:5Δ3,6,9,12,15 decreased, regardless of the type of nitrogen source applied. It was also found that the epiphytic bacterium Alteromonas macleodii played a particularly important role in releasing microalgae from the stress of amino acid deficiency. These findings also provide a foundation for regulating microalgal lipid production through manipulation of the nitrogen assimilation‐associated genes. 相似文献
19.
The effects of varying concentrations of nutrients present in Bold’s basal medium on the extent of colony formation from vegetative
fragments, sporulation and spore germination of the green algaStigeoclonium poscheri were studied. A decrease of colony formation was observed in media deficient in MgSO4, NaNO3, phosphates, and containing a 10-fold increase of H3BO3. Sporulation decreased in the same media. However, sporulation was greater in an increasing order in media containing 2-
to 10-fold increase in MgSO4. There was a decrease in spore germination in media deficient in phosphates, MgSO4, containing 5- or 10-fold MgSO4, or containing 2- to 10-fold of CaCl2, H3BO3 or microelements. Spore germination increased in media containing 2-fold MgSO4, deficient in H3BO3 or microelements or containing none of the three micronutrient solutions. 相似文献
20.
《Free radical research》2013,47(10):1239-1248
AbstractIonizing radiations such as X-ray and γ-ray can directly or indirectly produce clustered or multiple damages in DNA. Previous studies have reported that overexpression of DNA glycosylases in Escherichia coli (E. coli) and human lymphoblast cells caused increased sensitivity to γ-ray and X-ray irradiation. However, the effects and the mechanisms of other radiation, such as low dose rate radiation, heavy-ion beams, or hydrogen peroxide (H2O2), are still poorly understood. In the present study, we constructed a stable HeLaS3 cell line overexpressing human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) protein. We determined the survival of HeLaS3 and HeLaS3/hOGG1 cells exposed to UV, heavy-ion beams, γ-rays, and H2O2. The results showed that HeLaS3 cells overexpressing hOGG1 were more sensitive to γ-rays, OH?, and H2O2, but not to UV or heavy-ion beams, than control HeLaS3. We further determined the levels of 8-oxoG foci and of chromosomal double-strand breaks (DSBs) by detecting γ-H2AX foci formation in DNA. The results demonstrated that both γ-rays and H2O2 induced 8-oxoguanine (8-oxoG) foci formation in HeLaS3 cells. hOGG1-overexpressing cells had increased amounts of γ-H2AX foci and decreased amounts of 8-oxoG foci compared with HeLaS3 control cells. These results suggest that excess hOGG1 removes the oxidatively damaged 8-oxoG in DNA more efficiently and therefore generates more DSBs. Micronucleus formation also supported this conclusion. Low dose-rate γ-ray effects were also investigated. We first found that overexpression of hOGG1 also caused increased sensitivity to low dose rate γ-ray irradiation. The rate of micronucleus formation supported the notion that low dose rate irradiation increased genome instability. 相似文献