共查询到20条相似文献,搜索用时 15 毫秒
1.
Géza Kevács Miklós László György Rajkai Beáta Barnabás 《Plant Cell, Tissue and Organ Culture》1995,43(2):123-126
Maize (Zea mays L.) haploid cells were cultivated in a 1500 ml aerated and stirred batch bioreactor using modified BM medium. Cell growth was highly affected by pH and dissolved oxygen, and we observed two fairly distinct growth phases. During the first two days after inoculation at pH 5.8, oxygen consumption was high and the cells lowered the pH to a value around 4.3. After this period the pH stabilized at 4.5 and the dissolved oxygen reached a steady level. Decreasing dissolved oxygen concentration leads to lower growth rate and to higher pH. Both events mean stress conditions for the cell culture and probably result in increased genetic variability, and the loss of regeneration capacity. The stress condition during the adaptation phase can be eliminated by decreasing the pH of the medium to 4.7 before inoculation and by keeping dissolved oxygen above 40%. These conditions provide prolonged exponential growth dynamics and the cell suspensions could be the basis of large scale cultures also.Abbreviations 2,4-d
2,4-dichlorophenoxyacetitc acid
- NAA
naphthalene acetic acid 相似文献
2.
3.
Ohara M Yamaguchi Y Matsuura K Murakami S Arihiro K Okada M 《Cancer immunology, immunotherapy : CII》2009,58(3):441-447
Background The FOXP3 mRNA expression and the other regulatory T cell-related molecules were investigated and compared with clinicopathological
parameters in human primary breast cancer.
Method This study included 136 breast cancer patients operated in our department from 2003 to 2006. Total RNA was extracted from
frozen normal breast and breast cancer tissues, and the expression of FOXP3, IL-10, TGFβ1 and CCL22 mRNA was evaluated using quantitative real-time RT-PCR.
Result
FOXP3, IL-10,
TGFβ1 and CCL22 mRNA expressions were significantly higher in cancer tissue than in normal tissue, not only at pT1, 2, and 3 stages but also
at the DCIS stage. There were positive correlations between FOXP3 and IL-10, FOXP3 and TGFβ1, as well as FOXP3 and CCL22 mRNA expressions, respectively. FOXP3 and IL-10 mRNA expressions were significantly upregulated in PgR-negative or HER2-positive tumors.
Conclusion These results suggest that regulatory T cells are involved in tumor onset and progression in human primary breast cancer,
possibly contributing to poor prognosis of patients with breast cancer. 相似文献
4.
Drought Induces Oxidative Stress and Enhances the Activities of Antioxidant Enzymes in Growing Rice Seedlings 总被引:7,自引:0,他引:7
When rice seedlings grown for 10 and 20 days were subjected to in vitro drought stress of −0.5 and −2.0 MPa for 24 h, an increase in the concentration of superoxide anion (O2.−), increased level of lipid peroxidation and a decrease in the concentration of total soluble protein and thiols was observed
in stressed seedlings compared to controls. The concentration of H2O2 as well as ascorbic acid declined with imposition of drought stress, however glutathione (GSH) concentration declined only
under severe drought stress. The activities of total superoxide dismutases (SODs) as well as ascorbate peroxidase (APX) showed
consistent increases with increasing levels of drought stress, however catalase activity declined. Mild drought stressed plants
had higher guaiacol peroxidase (GPX) and chloroplastic ascorbate peroxidase (c-APX) activity than control grown plants but
the activity declined at the higher level of drought stress. The activities of enzymes involved in regeneration of ascorbate
i.e. monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were higher
in drought stressed plants compared to controls. Results suggest that drought stress induces oxidative stress in rice plants
and that besides SOD, the enzymes of ascorbate-glutathione cycle, which have not been studied in detail earlier under stressful
conditions, appear to function as important component of antioxidative defense system under drought stress. 相似文献
5.
The dynamics of planktonic cyanobacteria in eutrophicated freshwaters play an important role in formation of annual summer
blooms, yet overwintering mechanisms of these water bloom forming cyanobacteria remain unknown. The responses to darkness
and low temperature of three strains (unicellular Microcystis aeruginosa FACHB-905, colonial M. aeruginosa FACHB-938, and a green alga Scenedesmus
quadricauda FACHB-45) were investigated in the present study. After a 30-day incubation under darkness and low temperature, cell morphology,
cell numbers, chlorophyll a, photosynthetic activity (ETRmax and I
k), and malodialdehyde (MDA) content exhibited significant changes in Scenedesmus. In contrast, Microcystis aeruginosa cells did not change markedly in morphology, chlorophyll a, photosynthetic activity, and MDA content. The stress caused by low temperature and darkness resulted in an increase of the
antioxidative enzyme-catalase (CAT) in all three strains. When the three strains re-grew under routine cultivated condition
subjected to darkness and low temperature, specific growth rate of Scenedesmus was lower than that of Microcystis. Flow cytometry (FCM) examination indicated that two distinct types of metabolic response to darkness and low temperature
existed in the three strains. The results from the present study reveal that the cyanobacterium Microcystis, especially colonial Microcystis, has greater endurance and adaptation ability to the stress of darkness and low temperature than the green alga Scenedesmus.
Handling editor: D. Hamilton 相似文献
6.
Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria 总被引:7,自引:0,他引:7
Trcek J Toyama H Czuba J Misiewicz A Matsushita K 《Applied microbiology and biotechnology》2006,70(3):366-373
In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Ga. europaeus exhibited the highest resistance to acetic acid (10%), whereas Ga. intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal acetic acid production rate of Ga. europaeus slowly increased, but specific growth rates decreased concomitant with increased concentration of acetic acid in medium. The lag phase of A. pasteurianus was twice and four times longer in comparison to the lag phases of Ga. europaeus and Ga. intermedius, respectively. PQQ-dependent ADH activity was twice as high in Ga. europaeus and Ga. intermedius as in A. pasteurinus. The purified enzymes showed almost the same specific activity to each other, but in the presence of acetic acid, the enzyme activity decreased faster in A. pasteurianus and Ga. intermedius than in Ga. europaeus. These results suggest that high ADH activity in the Ga. europaeus cells and high acetic acid stability of the purified enzyme represent two of the unique features that enable this species to grow and stay metabolically active at extremely high concentrations of acetic acid. 相似文献
7.
Krasilnikova E. N. Tsaplina I. A. Zakharchuk L. M. Bogdanova T. I. 《Applied Biochemistry and Microbiology》2001,37(4):358-362
Aerobic thermoacidophilic chemolithotrophic bacteria Sulfobacillus thermosulfidooxidans1269Tand Sulfobacillus thermosulfidooxidanssubsp. asporogenes41 were shown to be resistant to stress factors, including high concentrations of Zn2+(0.8 M) and supraoptimal concentrations of H+(pH 1.2). The growth and biomass gain rates decreased, but bacteria retained their functions. The activity of nearly all enzymes involved in carbon metabolism decreased. Glucose was primarily metabolized via the Entner–Doudoroff pathway. The activity of tricarboxylic acid cycle enzymes decreased compared to that in cells grown under normal conditions. After saturation of the growth medium with 5 vol % CO2, sulfobacteria utilized glucose by the Embden–Meyerhof and pentose phosphate pathways under mixotrophic conditions. 相似文献
8.
Runlin Han C. Edward Ebert Zhihong Zhao Liming Li Heping Zhang Ruihua Tian 《World journal of microbiology & biotechnology》2005,21(6-7):1245-1248
Summary The characteristics of Bifidobacterium bifidum grown in solid state fermentation (SSF) system (water content of media 54.5 and 68.8%) was compared with the submerged fermentation
(SmF) system (water content of medium: 89.8%). Besides lactic acid (lactate) and acetic acid (acetate), the bacterium was
able to secrete propionic acid (propionate) and butyric acid (butyrate) under SSF conditions. However, it only produced lactate
and acetate under SmF conditions. The ratio of lactate to acetate was 1.26–1.62:1 in SSF but it was 1:2 in SmF. A higher content
of C16:0 and C18:1 as well as a lower content of C18:0 cell membrane fatty acids were observed in SSF than in SmF. There was
a lower growth rate, a lower viable count and a longer logarithmic growth phase for B. bifidum cultivated in SSF than in SmF. 相似文献
9.
10.
A novel cold-tolerant fungus, Fibulorhizoctonia psychrophila, was isolated from a refrigerated carrot storage facility and identified as an anamorph of Athelia, often classified in Rhizoctonia s.l. Growth of this fungus was observed between 0 and 20°C with an optimum at 9–12°C, while incubation of mycelium grown at
15–32°C resulted in absence of growth even after the fungus was transferred back to 15°C. Growth was inhibited in the presence
of the antifungals sorbic acid or natamycin, in particular when the fungus was incubated at 18°C. F. psychrophila produces polysaccharide degrading enzymes that, when compared to enzymes from the ascomycete fungus Aspergillus niger, retain a larger proportion of their activity at lower temperatures. This indicates that F. psychrophila could be used as a source for novel industrial enzymes that are active at 4–15°C. 相似文献
11.
In the present investigation, we studied the possible potentiating effect of salicylic acid (SA) under Cd toxicity in Oryza sativa L. leaves. Cd treatments for 24 h reduced the shoot length, dry biomass and total chlorophyll content followed by high Cd
accumulation in shoots. About 16 h presoaking with SA resulted in partial protection against Cd, as observed by minor changes
in length, biomass and total chlorophyll. SA priming resulted in low Cd accumulation. Enhanced thiobarbituric acid reactive
substances (TBARS), hydrogen peroxide (H2O2) and superoxide anion (O2
−) content were seen when Cd was applied alone, while under SA priming the extent of TBARS, H2O2 and O2
− were significantly low, suggesting SA-regulated protection against oxidative stress. The antioxidant enzymes like Catalase
(CAT), guaiacol peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD) showed varied activities under
Cd alone. CAT activity increased after Cd treatment, followed by a decline in GPX and GR activity. SOD also declined at the
highest concentrations with an initial increase. Under SA-priming conditions, the efficiency of the antioxidant enzymes was
significantly elevated. GPx and SOD activity showed significant increase in activity. The ascorbate activity increased after
Cd treatment, followed by a decline in glutathione under SA-free condition. SA priming showed gradual increase in these non-enzymic
antioxidants. Our results indicate that Cd-induced oxidative stress can be regulated by SA. 相似文献
12.
Antimould activity of sourdough lactic acid bacteria: identification of a mixture of organic acids produced by Lactobacillus sanfrancisco CB1 总被引:1,自引:0,他引:1
A. Corsetti M. Gobbetti J. Rossi P. Damiani 《Applied microbiology and biotechnology》1998,50(2):253-256
Sourdough lactic acid bacteria, cultivated in wheat flour hydrolysate, produced antimould compounds. The antimould activity
varied greatly among the strains and was mainly detected within obligately heterofermentative Lactobacillus spp. Among these, Lb. sanfrancisco CB1 had the largest spectrum. It inhibited moulds related to bread spoilage such as Fusarium, Penicillium, Aspergillus and Monilia. A mixture of acetic, caproic, formic, propionic, butyric and n-valeric acids, acting in a synergistic way, was responsible for the antimould activity. Caproic acid played a key role in
inhibiting mould growth.
Received: 20 January 1998 / Received revision: 17 April 1998 / Accepted: 27 April 1998 相似文献
13.
Yoshihiro Ojima Mizuho Komaki Motomu Nishioka Shintaro Iwatani Nobuharu Tsujimoto Masahito Taya 《Biotechnology letters》2009,31(4):525-530
A stress-responsive gene, yggG, was introduced into an l-phenylalanine producer, Escherichia coli AJ12741. In shake-flask culture, the yggG-containing recombinant strain (named AJ12741/pHYGG) produced 6.4 g l-phenylalanine l−1 at the end of culture and its yield on glucose was 0.16 g l-phenylalanine g glucose−1. These values are much higher than those of the original AJ12741 strain (3.7 g l-phenylalanine l−1 and 0.09 g l-phenylalanine g glucose−1, respectively). On the other hand, AJ12741/pHYGG strain produced only 4.5 g acetic acid l−1 and its yield on glucose was about a half of that of the AJ12741 culture. Analysis of gene expression revealed that in late
growth phase, the expression levels of genes involved in acetic acid production (pta, ackA, and poxB) were relatively low in AJ12741/pHYGG cells. In particular, the level of poxB expression in AJ12741/pHYGG strains was one-seventh of that of the original strain. These results suggest that the formation
of a bottleneck for acetic acid production brings about a metabolic flow favorable to l-phenylalanine synthesis in the recombinant strain over-expressing the yggG gene.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Glutaminase is widely distributed among microorganisms and mammals with important functions. Little is known regarding the
biochemical properties and functions of the deamidating enzyme glutaminase in cyanobacteria. In this study a putative glutaminase
encoded by gene slr2079 in Synechocystis sp. PCC 6803 was investigated. The slr2079 was expressed as histidine-tagged fusion protein in Escherichia coli. The purified protein possessed glutaminase activity, validating the functional assignment of the genomic annotation. The
apparent K
m value of the recombinant protein for glutamine was 26.6 ± 0.9 mmol/L, which was comparable to that for some of other microbial
glutaminases. Analysis of the purified protein revealed a two-fold increase in catalytic activity in the presence of 1 mol/L
Na+. Moreover, the K
m value was decreased to 12.2 ± 1.9 mmol/L in the presence of Na+. These data demonstrate that the recombinant protein Slr2079 is a glutaminase which is regulated by Na+ through increasing its affinity for substrate glutamine. The slr2079 gene was successfully disrupted in Synechocystis by targeted mutagenesis and the Δslr2079 mutant strain was analyzed. No differences in cell growth and oxygen evolution rate were observed between Δslr2079 and the wild type under standard growth conditions, demonstrating slr2079 is not essential in Synechocystis. Under high salt stress condition, however, Δslr2079 cells grew 1.25-fold faster than wild-type cells. Moreover, the photosynthetic oxygen evolution rate of Δslr2079 cells was higher than that of the wild-type. To further characterize this phenotype, a number of salt stress-related genes
were analyzed by semi-quantitative RT-PCR. Expression of gdhB and prc was enhanced and expression of desD and guaA was repressed in Δslr2079 compared to the wild type. In addition, expression of two key enzymes of ammonium assimilation in cyanobacteria, glutamine
synthetase (GS) and glutamate synthase (GOGAT) was examined by semi-quantitative RT-PCR. Expression of GOGAT was enhanced
in Δslr2079 compared to the wild type while GS expression was unchanged. The results indicate that slr2079 functions in the salt stress response by regulating the expression of salt stress related genes and might not play a major
role in glutamine breakdown in Synechocystis.
Supported by the National Natural Sciences Foundation of China (Grant No. 30500108) and Hundred Talents Program of Chinese
Academy of Sciences. 相似文献
15.
Fatemeh Rafii Miseon Park Gonçalo Gamboa da Costa Luisa Camacho 《Archives of microbiology》2009,191(12):895-902
The production of short-chain fatty acids, reductive enzymes, and hydrolytic enzymes by four gatifloxacin-selected, fluoroquinolone-resistant,
mutant strains of C. perfringens, with stable mutations either in DNA gyrase or in both DNA gyrase and topoisomerase IV, was compared with that produced by
the wild-type parent strains to investigate the effect of mutations associated with the selection of gatifloxacin resistance
on bacterial metabolic activities. The mutants differed from their respective wild-type parent strains in the enzymatic activities
of azoreductase, nitroreductase, and β-glucosidase and in the ratio of butyric acid to acetic acid production. Microarray
analysis of one wild type and the corresponding mutant revealed different levels of mRNA expression for the enzymes involved
in short-chain fatty acid (SCFA) synthesis and for β-glucosidase and oxidoreductases. In addition to mutations in the target
genes, selection of resistance to gatifloxacin resulted in strain-specific physiological changes in the resistant mutants
of C. perfringens that affected their metabolic activities. 相似文献
16.
Inui M Suda M Kimura S Yasuda K Suzuki H Toda H Yamamoto S Okino S Suzuki N Yukawa H 《Applied microbiology and biotechnology》2008,77(6):1305-1316
A recombinant butanol pathway composed of Clostridium acetobutylicum ATCC 824 genes, thiL, hbd, crt, bcd-etfB-etfA, and adhe1 (or adhe) coding for acetyl-CoA acetyltransferase (THL), β-hydroxybutyryl-CoA dehydrogenase (HBD), 3-hydroxybutyryl-CoA dehydratase
(CRT), butyryl-CoA dehydrogenase (BCD), butyraldehyde dehydrogenase (BYDH), and butanol dehydrogenase (BDH), under the tac promoter control was constructed and was introduced into Escherichia coli. The functional expression of these six enzymes was proved by demonstrating the corresponding enzyme activities using spectrophotometric,
high performance liquid chromatography and gas chromatography analyses. The BCD activity, which was not detected in E. coli previously, was shown in the present study by performing the procedure from cell extract preparation to activity measurement
under anaerobic condition. Moreover, the etfA and etfB co-expression was found to be essential for the BCD activity. In the case of BYDH activity, the adhe gene product was shown to have higher specificity towards butyryl-CoA compared to the adhe1 product. Butanol production from glucose was achieved by the highly concentrated cells of the butanologenic E. coli strains, BUT1 with adhe1 and BUT2 with adhe, under anaerobic condition, and the BUT1 and BUT2 strains were shown to produce 4 and 16-mM butanol with 6- and 1-mM butyrate
as a byproduct, respectively. This study reports the novel butanol production by an aerobically pregrown microorganism possessing
the genes of a strict anaerobe, Clostridium acetobutylicum. 相似文献
17.
We isolated the 5′ flanking region of a gene for phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) from Pinus taeda, PtaPAL. To investigate the tissue-specific expression of the PtaPAL promoter, histochemical assay of GUS activity was performed using the transgenic tobacco expressing the PtaPAL promoter-GUS. The region of −897 to −420 in PtaPAL promoter showed high activities in the secondary xylem and response to bending stress. To characterize the cis-regulatory functions of the promoters for enzymes in phenylpropanoid biosynthesis, we examined the activity of chimeric promoters
of PtaPAL and a 4-coumarate CoA ligase, Pta4CLα. The chimeric promoter showed similar activity as the Pta4CLα promoter. Electrophoretic mobility shift assays implicated −897 to –674 of PtaPAL promoter containing cis-elements of the expression in xylem of Pinus taeda. The results suggested that AC elements of PtaPAL have multiple functions in the expression under the various developmental stages and stress conditions in the transgenic
tobacco.
The nucleotide sequence data reported will appear in the EMBL, GenBank, and DDBJ Nucleotide Sequence Databases under the accession
number AB449103 (PtaPAL promoter sequence). 相似文献
18.
Lin Jie Zhang Zhao Li Wu Kuan Fu Wang Qun Liu Hua Mei Zhuang Gang Wu 《Ecology and evolution》2015,5(2):515-530
Fitness costs associated with resistance to insecticides have been well documented, usually at normal temperature conditions, in many insect species. In this study, using chlorpyrifos‐resistant homozygote (RR) and chlorpyrifos‐susceptible homozygote (SS) of resistance ace1 allele of Plutella xylostella (DBM), we confirmed firstly that high temperature experience in pupal stage influenced phenotype of wing venation in insecticide‐resistant and insecticide‐susceptible Plutella xylostella, and SS DBM showed significantly higher thermal tolerance and lower damages of wing veins under heat stress than RR DBM. As compared to SS DBM, RR DBM displayed significantly lower AChE sensitivity to chlorpyrifos, higher basal GSTs activity and P450 production at 25°C, but higher inhibitions on the enzyme activities and P450 production as well as reduced resistance to chlorpyrifos under heat stress. Furthermore, RR DBM displayed significantly higher basal expressions of hsp69s, hsp72s, hsp20, hsp90, Apaf‐1, and caspase‐7 at 25°C, but lower induced expressions of hsps and higher induced expressions of Apaf‐1, caspase‐9, and caspase‐7 under heat stress. These results suggest that fitness costs of chlorpyrifos resistance in DBM may partly attribute to excess consumption of energy caused by over production of detoxification enzymes and hsps when the proteins are less demanded at conducive environments but reduced expressions when they are highly demanded by the insects to combat environmental stresses, or to excess expressions of apoptotic genes under heat stress, which results in higher apoptosis. The evolutionary and ecological implications of these findings at global warming are discussed. 相似文献
19.
Embryogenic callus in Catharanthus roseus was initiated from hypocotyl on Murashige and Skoog’s (MS) medium supplemented with 1.0–2.0 mg dm−3 of 2,4-dichlorophenoxyacetic acid (2,4-D) or chlorophenoxyacetic acid (CPA). Calli from other sources were non-embryogenic.
Numerous somatic embryos were induced from primary callus on MS medium suplemented with naphthalene acetic acid (NAA) within
two weeks of culture. Embryo proliferation was much faster on medium supplemented with 6-benzylaminopurine (BAP). After transfer
to medium with gibberellic acid (GA3, 1.0 mg dm− 3) mature green embryos were developed and germinated well into plantlets on MS liquid medium supplemented with 0.5 mg dm−3 BAP. Later, embryos with cotyledonary leaves were subjected to different auxins treatments for the development of roots.
Before transfer ex vitro, plantlets were cultivated on half strength MS medium containing 3 % sucrose and 0.5 mg dm−3 BAP for additional 2 weeks. Additionally, the effect of liquid medium has been evaluated at different morphogenetic stages. 相似文献