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1.
Stress tolerance is a multigenic character and there are many stress responsive genes, which are stress specific. Although
many of these have been cloned, their functional significance remains fragmentary. Hence it is important to identify the relevant
stress genes involved in altering the metabolism for adaptation. Overexpression is one of the several approaches and Chlamydomonas is a suitable system to study the functional relevance of stress genes. Stress responses can only be assessed on prior exposure
to sublethal induction stress. In this study the acclimation response of Chlamydomonas was assessed for different abiotic stresses using physiological screens like chlorophyll stability, membrane damage, cell
viability, accumulation of free radicals, survival and recovery growth. We demonstrate that Chlamydomonas responds to diverse stresses and is a potential system to study the relevance of stress genes. The relevance of choline oxidase
A (codA), a key enzyme in glycinebetaine biosynthesis, was examined by developing transformants expressing codA gene from Arthrobacter globiformis. Southern positive transformants showed enhanced accumulation of glycinebetaine. The transformants also showed enhanced growth
under salinity, high light coupled with methylviologen-induced oxidative stress, high temperature and cold stress. However
the transgenics were not tolerant to PEG-mediated simulated osmotic stress, LiCl, menadione and UV stress. Increased cell
survival and decreased chlorophyll degradation in transformants under acclimated conditions further confirmed the relevance
of codA in imparting stress tolerance. Our results indicated that the relevance of stress responsive genes can be efficiently validated
for diverse abiotic stresses using Chlamydomonas system.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
R. Hema and M. Senthil-Kumar contributed equally. 相似文献
2.
依据NCBI数据库OsPM1的序列信息,采用PCR技术扩增获取OsPM1的2 100bp的启动子序列。利用PLACE预测启动子的顺式作用元件分析表明,启动子内含有大量与胁迫相关的顺式作用元件,主要有ABA响应相关元件、脱水响应元件、低温响应元件、热激响应元件和转录因子结合元件。构建OsPM1的启动子和GUS基因融合表达载体,转入拟南芥。组织化学染色分析结果显示,非生物胁迫处理前,幼苗中GUS基因表达水平很低;干旱、低温、高盐等胁迫处理后,GUS基因表达量显著升高。研究表明,OsPM1的启动子能够显著提高在干旱、高盐和低温处理后下游基因的表达水平。 相似文献
3.
Under conditions of the spontaneous or induced autolysis of thick cell suspensions,Arthrobacter globiformis strains produced cells exhibiting features typical of resting microbial forms. The number of viable resting cells was greater
under conditions of induced rather than spontaneous autolysis. The thermoresistance of the resting cells of A.globiformis strains isolated from 2-to 3 million-year-old permafrost was higher than that of the collectionA. globiformis strain. 相似文献
4.
Rhodopseudomonas globiformis strain 7950 grew with a variety of amino acids, urea, or N2 as sole nitrogen sources. Cultures grown on N2 reduced acetylene to ethylene; this activity was absent from cells grown on nonlimiting NH
4
+
. Glutamate dehydrogenase could not be detected in extracts of cells of strain 7950, although low levels of an alanine dehydrogenase were present. Growth ofR. globiformis on NH
4
+
was severely inhibited by the glutamate analogue and glutamine synthetase inhibitor, methionine sulfoximine. High levels of glutamine synthetase (as measured in the -glutamyl transferase assay) were observed in cell extracts of strain 7950 regardless of the nitrogen source, although N2 and amino acid grown cells contained somewhat higher glutamine synthetase contents than cells grown on excess NH
4
+
. Levels of glutamate synthase inR. globiformis were consistent with that reported from other phototrophic bacteria. Both glutamate synthase and alanine dehydrogenase were linked to NADH as coenzyme. We conclude thatR. globiformis is capable of fixing N2, and assimilates NH
4
+
primarily via the glutamine synthetase/glutamate synthase pathway.Abbreviations GS
glutamine synthetase
- GOGAT
Glutamineoxoglutarate aminotransferase
- GDH
Glutamate dehydrogenase
- ADH
Alanine dehydrogenase
- MSO
Methionine sulfoximine 相似文献
5.
In an attempt to increase tolerance to salinity stress in tobacco plants, the genes encoding the mutant form of glutamyl kinase
(proB), pyrroline-5-carboxylate synthetase, and osmotin were cloned into three different shuttle vectors and were separately introduced
into the tobacco plants. The transgenic lines were compared for their ability to produce shoots and grow in MS medium containing
320 mM NaCl; it was shown that the transgenic lines containing genetically handled osmotin gene are more resistant to salinity. The amount of chlorophyll a was used to show continuing growth of plant lines. The results showed that only the tobacco lines transformed with the modified
osmotin gene exhibited greater tolerance to salinity.
Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 122–127.
The text was submitted by the authors in English. 相似文献
6.
Gloria Viviana Cerrillo-Rojas Mariana Tiscareño-Andrade Ana Erika Ochoa-Alfaro Eugenio Pérez-Molphe Balch Ruth Elena Soria-Guerra José Francisco Morales-Domínguez 《Phyton》2020,89(3):715-726
Halophytes are an excellent choice for the study of genes conferring
salt tolerance to salt-sensitive plants and, they are suitable for reclamation and
remediation of saline soil. We develop an in vitro plant propagation protocol
and studies of genes involved with GB and Pro biosynthesis in Suaeda edulis.
Axillary buds were used as explants and cultured in different treatments on Murashige and Skoog (MS) medium supplemented with different concentrations and
combinations of plant growth regulators. The highest number of multiple shoots
was on MS medium containing 1 mg/L Benzyladenine (BA) and / or 2 g/L activated carbon with 5.5 ± 06 shoots per explant. The identification and expression
analysis of genes involved in glycine betaine (GB) biosynthesis were S-adenosylmethionine synthetase (SAMS), choline monooxygenase (CMO) and betaine aldehyde dehydrogenase (BADH), and for proline (Pro) was pyrroline 5-carboxylate
synthetase (P5CS). These sequences shared 90–95% of identity with others plant
homologous in public databases. The amino acids sequence analysis showed that
all these peptides contain some of the conserved motifs of those kinds of
enzymes. The qRT-PCR analysis revealed a higher expression of SeBADH,
SeCMO, and, SeP5CS genes in the roots and leaves from plants collected in
the field in contrast with from in vitro plants. However, the expression level of
SeSAMS was higher only in the leaves of plants collected in the field when compared to those cultivated in vitro. 相似文献
7.
8.
Transformation of Synechococcus with a gene for choline oxidase enhances tolerance to salt stress 总被引:12,自引:0,他引:12
Patcharaporn Deshnium Dmitry A. Los Hidenori Hayashi Laszlo Mustardy Norio Murata 《Plant molecular biology》1995,29(5):897-907
Choline oxidase, isolated from the soil bacterium Arthrobacter globiformis, converts choline to glycinebetaine (N-trimethylglycine) without a requirement for any cofactors. The gene for this enzyme, designated codA, was cloned and introduced into the cyanobacterium Synechococcus sp. PCC 7942. The codA gene was experssed under the control of a strong constitutive promoter, and the transformed cells accumulated glycinebetaine at intracellular levels of 60–80 mM. Consequently the cells acquired tolerance to salt stress, as evaluated in terms of growth, accumulation of chlorophyll and photosynthetic activity. 相似文献
9.
10.
Glycinebetaine increases chilling tolerance and reduces chilling-induced lipid peroxidation in Zea mays L. 总被引:3,自引:2,他引:1
Chilling tolerance was increased in suspension‐cultured cells and seedlings of maize (Zea mays L. cv ‘Black Mexican Sweet’) grown in media containing glycinebetaine (GB). A triphenyl tetrazolium chloride (TTC) reduction test indicated that after a 7 d chilling period at 4 °C, cells treated with 1 mm GB at 26 °C for 1 d had a survival rate (30%) that was twice as high as that of untreated controls. The addition of 2·5 m M GB to the culture medium resulted in maximum chilling tolerance (40%). The results of a cell regrowth assay were consistent with viability determined by the TTC method. In suspension‐cultured cells supplemented with various concentrations of GB, accumulation of GB in the cells was proportional to the GB concentration in the medium and was saturated at a concentration of 240 μ mol (g DW) ? 1. The degree of increased chilling tolerance was positively correlated with the level of GB accumulated in the cells. The increased chilling tolerance was time‐dependent; i.e. it was first observed 3 h after treatment and reached a plateau after 14 h. Feeding seedlings with 2·5 m M GB through the roots also improved their chilling tolerance, as evidenced by the prevention of chlorosis after chilling for 3 d at 4 °C/2 °C. Lipid peroxidation, as expressed by the production of malondialdehyde, was significantly reduced in GB‐treated cells compared with the untreated controls during chilling. These results suggest that increased chilling tolerance may be due, in part, to the reduction of lipid peroxidation of the cell membranes in the presence of GB. 相似文献
11.
A. L. Mulyukin E. V. Demkina N. A. Kryazhevskikh N. E. Suzina L. I. Vorob’eva V. I. Duda V. F. Galchenko G. I. El-Registan 《Microbiology》2009,78(4):407-418
The colony-forming ability of long (3–9 months) incubated cystlike resting cells (CRC) of the nonspore-forming gram-positive bacteria Micrococcus luteus and Arthrobacter globiformis was studied in this work. The preservation of the CRC proliferative potential as assayed by plating on standard LB agar was shown to depend on the conditions of the formation of the dormant cells. In aged post-stationary cultures of micrococci and arthrobacters grown under carbon and phosphorus limitation the number of colony-forming units (CFU/ml) of CRC decreased in the course of 3–9 month incubation to the level of 106–107 CFU/ml. However, M. luteus CRC obtained under carbon and nitrogen limitation and A. globiformis CRC obtained under nitrogen limitation and starvation completely lost their ability to form colonies on standard solid medium after 4–6 months of incubation and turned into a ‘non-culturable’ (non-platable) state. In this case, the ratio of live cells in the population of M. luteus and A. globiformis ‘non-culturable’ CRCs (determined by the Live/Dead staining test) was 10–44% of the total cell number. To study the possible preservation of proliferative potential in non-platable CRCs, various methods of their reactivation were applied. Although preincubation of CRC suspensions in a buffer solution of 0.1 M K2HPO4 (pH 7.4) or in the presence of lysozyme (1 or 10 μg/ml) resulted in increased numbers of live cells (determined by the Live/Dead test) or in disruption of the cell conglomerates, it did not increase considerably the CFU titer on LB medium. Variations in the medium composition, such as addition of sodium pyruvate as an antioxidant or dilution of the medium, promoted the formation of macrocolonies by a small portion of nonplateable CRC of M. luteus (50?80 CFU/ml), whereas the number of the cells capable of microcolony formation (mCFU) was 1.8–6.8 × 105 mCFU/ml, exceeding the CFU titers by four orders of magnitude. The application of semisolid agar and the most probable number (MPN) method was the most efficient for determination of the mCFU titer, and an almost complete reversion of ‘non-culturable’ micrococcal CRCs to microcolony formation was observed (up to 2.3 × 107 mCFU/ml). The usefulness of diluted complete media for the restoration of the colony-forming ability of the dormant forms was confirmed in experiments with ‘nonculturable’ CRCs of A. globiformis. The development of special procedures and methods for determining actively proliferating cells not detected by ordinary methods is of great importance for advanced monitoring studies. 相似文献
12.
Plant growth promoting rhizobacteria such as Azospirillum brasilense are agronomically important as they are frequently used for crop inoculation. But adverse factors such as increasing soil
salinity limit their survival, multiplication and phytostimulatory effect. In order to understand the role of the genes involved
in the adaptation of A. brasilense Sp7 to salt stress, a mutant library (6,800 mutants) was constructed after random integration of a mini-Transposon Tn5 derivative
containing a promoterless gusA and oriV. The library was screened for salt stress inducible Gus activity on minimal malate agar medium containing NaCl and 5-bromo-4-chloro-3-indolyl-β-d-glucuronide. Salt stress responsiveness of the promoters was estimated by quantifying GusA activity in the presence and absence
of NaCl stress using p-nitrophenyl-β-d-glucuronide as a substrate. In 11 mutants showing high levels of gusA expression in the presence of salt-stress, the partial nucleotide sequence of the DNA region flanking the site of Tn5 insertion
was determined and analysed using the NCBI-BLAST programs. Similarity searches revealed that 10 out of the 11 genes sequenced
showed notable similarity with genes involved in functions related to modulation in the composition of exopolysaccharides,
capsular polysaccharides, lipopolysaccharides, peptidoglycan and lipid bilayer of the cell envelope. Induction of cell envelope
related genes in response to salt stress and salt sensitive phenotype of several mutants in A. brasilense indicate a prominent role of cell envelope in salt-stress adaptation. 相似文献
13.
Ying He Chunmei He Lihua Li Zhili Liu Aifang Yang Juren Zhang 《Molecular biology reports》2011,38(1):657-666
The glycine-methylation biosynthetic pathway of glycinebetaine (GB) has been investigated, but only a few studies on GB accumulation
in transgenic higher plants have utilized this pathway. In this study, two methyltransferase genes named ApGSMT2 and ApDMT2, encoding proteins catalyzing GB biosynthesis from glycine, were cloned from a relative strain of Aphanothece halophytica. The potential roles of ApGSMT2 and ApDMT2 in GB synthesis were first examined in transgenic Escherichia coli, which had increased levels of GB and improved salt tolerance. Then ApGSMT2 and ApDMT2 were transferred into tobacco. Compared with transgenic tobacco expressing betA, transgenic tobacco co-expressing ApGSMT2 and ApDMT2 accumulated more GB and exhibited enhanced drought resistance with better germination performance, higher relative water
content, less cell membrane damage and better photosynthetic capacity under drought stress. We concluded that the ApGSMT2 and ApDMT2 genes cloned in this study will be very useful for engineering GB-accumulating transgenic plants with enhanced drought resistance. 相似文献
14.
Investigations showed that Rhodococcus erythropolis E-15 and Arthrobacter globiformis 2F cells respond to osmotic shock by increasing the synthesis of free amino acids, primarily glutamic acid (80% of the intracellular free amino acid pool). The osmoprotective role of glutamic acid follows from its beneficial effect on the growth of bacteria in high-salinity media. It was found that the addition of this amino acid to the growth medium at a concentration of 2 mM shortened the lag phase and increased the growth rate and biomass yield of either of the two bacteria. The addition of another osmoprotectant, trehalose, to the high-salinity growth medium of R. erythropolis E-15 at the same concentration (2 mM), restored the growth parameters of this bacterium to the control values. 相似文献
15.
A 1.2kb DNA fragment was cloned from Synechococcus sp. PCC7942, which is able phenotypicalty to complement a phoRcreC Escherichia coli mutant for the expression of alkaline phosphatase. A 2.5kb DNA fragment encompassing the putative gene was then cloned and its complete nucleotide sequence determined. Nucleotide sequencing revealed that the intact gene encodes a protein of 46389 Da, and that the deduced amino acid sequence shows a high degree of homology to those of the bacterial sensory kinase family. In the determined nucleotide sequence, another gene was adjacently located, which encodes a protein of 29012Da. This protein shows a high degree of homology to those of the response regulator family. Thus, we succeeded in the cloning of a pair of genes encoding the sensory kinase and response regulator, respectively, in a cyanobacterium. Mutant strains that lack these genes were constructed, and demonstrated to be defective in their ability to produce alkaline phosphatase and some inducible proteins in response to phosphate-limitation in the medium. These results imply that the gene products identified in this study are probably involved, either directly or indirectly, in the signal-transduction mechanism underlying regulation of the phosphate regulon in Synechococcus sp. PCC7942. Hence, the genes encoding the sensory kinase and response regulator were designated as sphS and sphR, respectively (S ynechococcusph osphate regulon). The SphS protein was demonstrated in vitro to undergo phosphorylation in the presence of ATP. 相似文献
16.
Degradation of Substituted Phenylurea Herbicides by Arthrobacter globiformis Strain D47 and Characterization of a Plasmid-Associated Hydrolase Gene, puhA
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Gillian A. Turnbull Margaret Ousley Allan Walker Eve Shaw J. Alun W. Morgan 《Applied microbiology》2001,67(5):2270-2275
Arthrobacter globiformis D47 was shown to degrade a range of substituted phenylurea herbicides in soil. This strain contained two plasmids of approximately 47 kb (pHRIM620) and 34 kb (pHRIM621). Plasmid-curing experiments produced plasmid-free strains as well as strains containing either the 47- or the 34-kb plasmid. The strains were tested for their ability to degrade diuron, which demonstrated that the degradative genes were located on the 47-kb plasmid. Studies on the growth of these strains indicated that the ability to degrade diuron did not offer a selective advantage to A. globiformis D47 on minimal medium designed to contain the herbicide as a sole carbon source. The location of the genes on a plasmid and a lack of selection would explain why the degradative phenotype, as with many other pesticide-degrading bacteria, can be lost on subculture. A 22-kb EcoRI fragment of plasmid pHRIM620 was expressed in Escherichia coli and enabled cells to degrade diuron. Transposon mutagenesis of this fragment identified one open reading frame that was essential for enzyme activity. A smaller subclone of this gene (2.5 kb) expressed in E. coli coded for the protein that degraded diuron. This gene and its predicted protein sequence showed only a low level of protein identity (25% over ca. 440 amino acids) to other database sequences and was named after the enzyme it encoded, phenylurea hydrolase (puhA gene). 相似文献
17.
E. Van den Eynde L. Vriens M. Wynants H. Verachtert 《Applied microbiology and biotechnology》1984,19(1):44-52
Summary Pure culture transient experiments with Arthrobacter globiformis and Sphaerotilus natans revealed that the floc-forming species A. globiformis can adapt better to intermittent feeding (I-feeding) than the filamentous species S. natans. The floc-forming bacterium showed a larger overcapacity for substrate uptake, a larger accumulation of reserves (polysaccharides and poly--hydroxybutyric acid) and a more efficient mobilization of these polymers. As a consequence A. globiformis became dominant in an I-fed dual culture of S. natans and A. globiformis. The transient behaviour of filamentous continuously fed (C-fed) sludge was similar to the response of S. natans. Consequently, I-feeding of activated sludge could prevent the excessive growth of filamentous bacteria. I-fed sludge, showed a higher overcapacity, the accumulation of more reserves and a shorter lag phase in protein synthesis than C-fed activated sludge, during the transient response, after a pulse dose of substrate. However, to be effective in the control of bulking, the frequency of I-feeding should allow for a sufficiently long endogenous phase. In addition the available fraction of the COD is important in the optimization of I-feeding as a control strategy for filamentous bulking. 相似文献
18.
19.
A liquid culture medium (GB) forNeisseria gonorrhoeae is described. Except hemin, the GB medium does not contain blood products. Liver digest, proteose peptone and Yeastolate
were used as the main carbon/nitrogen sources. The medium permitted growth, with a satisfactory cell yield, of all but one
of the 68 gonococcal strains tested. Cysteine-hydrochloride was used to achieve an adequate redox-potential of the medium.
The optimal pH of the ready-to-use medium was found to be 7.4. Comparative culture studies showed that the GB medium has advantages
compared to earlier recommended broth media for the growth of gonococci in the percentage of consecutive gonococcal strains
isolated from clinical specimens that grew in the medium. The addition of 1.4% purified agar permitted the use of the medium
as a transparent solid medium for the culture of gonococci. The possibility to make the GB medium selective for gonococci
by addition of trimethoprim, polymyxin B and E, and natamycin was also evaluated. In this respect, vancomycin-colistin-nystatin
and mycostatin were also tested. The GB medium is inexpensive and easy to prepare. 相似文献
20.
Johannes F. Imhoff Johann Then Fuad Hashwa Hans G. Trüper 《Archives of microbiology》1981,130(3):234-237
Rhodopseudomonas globiformis is able to grow on sulfate as sole source of sulfur, but only at concentrations below 1 mM. Good growth was observed with thiosulfate, cysteine or methionine as sulfur sources. Tetrathionate supported slow growth. Sulfide and sulfite were growth inhibitory. Growth inhibition by higher sulfate concentrations was overcome by the addition of O-acetylserine, which is known as derepressor of sulfate-assimilating enzymes, and by reduced glutathione. All enzymes of the sulfate assimilation pathway. ATP-sulfurylase, adenylylphosphate-sulfotransferase, thiosulfonate reductase and O-acetylserine sulfhydrylase are present in R. globiformis. Sulfate was taken up by the cells and the sulfur incorporated into the amino acids cysteine, methionine and homocysteine. It is concluded, that the failure of R. globiformis to grow on higher concentrations of sulfate is caused by disregulation of the sulfate assimilation pathway. Some preliminary evidence for this view is given in comparing the activities of some of the involved enzymes after growth on different sulfur sources and by examining the effect of O-acetylserine on these activities.Abbreviations DTE
dl-dithioerythritol
- APS
adenosine 5-phosphosulfate, adenylyl sulfate
- PAPS
3-phosphoadenosine 5-phosphosulfate, 3-phosphoadenylylsulfate 相似文献