共查询到20条相似文献,搜索用时 156 毫秒
1.
Lamitina ST Morrison R Moeckel GW Strange K 《American journal of physiology. Cell physiology》2004,286(4):C785-C791
2.
Chromosomal transformation in the cyanobacterium Agmenellum quadruplicatum. 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chromosomal transformation of Agmenellum quadruplicatum PR-6 (= Synechococcus sp. strain 7002) was characterized for phenotypic expression, for exposure time to DNA, and for dependence on DNA concentration with regard to Rifr donor DNA. Exponentially growing cells of PR-6 were competent for chromosomal transformation. Competence decreased in cells in the stationary phase of growth or in cells deprived of a nitrogen source. Dark incubation of cells before exposure to donor DNA also decreased competence. Homologous Rifr and Strr DNA and heterologous Escherichia coli W3110 DNA were used in DNA-DNA competition studies, which clearly showed that DNA binding by PR-6 was nonspecific. DNA binding and uptake by PR-6 exhibited single-hit kinetics. Single-stranded DNA failed to transform competent cells of PR-6, and DNA eclipse was not observed, suggesting that double-stranded DNA was the substrate for the binding and uptake reactions during the transformation of PR-6. A significant improvement in transformation frequency was achieved by increasing the nitrate content of the culture medium and by lowering the temperature at which cells were exposed to donor DNA from 39 degrees C (the optimal temperature for growth) to 30 degrees C. 相似文献
3.
Plasmid transformation in Agmenellum quadruplicatum PR-6: construction of biphasic plasmids and characterization of their transformation properties. 总被引:20,自引:13,他引:7
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Biphasic, chimeric plasmids for the transformation of Agmenellum quadruplicatum PR-6 (Synechococcus sp. strain 7002) were constructed by splicing the 3.0-megadalton cryptic plasmid from strain PR-6 into plasmids pBR322 and pBR325 from Escherichia coli. Transformants of either E. coli or strain PR-6 by these plasmids could be detected on the basis of the drug resistance marker(s) carried by the chimeric plasmids. Plasmid DNA isolated from a PR-6 transformant transformed PR-6 much more efficiently than plasmid DNA prepared from E. coli. Plasmids from which the AvaI recognition site was deleted (AvaI is an isoschizomer of the AquI restriction endonuclease of strain PR-6) also transformed strain PR-6 much more efficiently than did plasmids containing the AvaI recognition site. These and other results suggest that AquI strongly effects plasmid transformation when the donor plasmid contains an unmodified AquI recognition site. Multimeric forms of the chimeric plasmids are also much more efficient at transforming strain PR-6 than are the analogous monomeric forms. 相似文献
4.
The strain Penicillium purpurogenum P-26 was subjected to UV irradiation and N-methyl-N′-nitro-N-nitrosoguanidine treatment and mutants were isolated capable of synthesizing cellulase under the conditions of a high concentration
of glucose. Initially mutants resistant to catabolite repression by 2-deoxy-D-glucose were isolated on Walseth’s cellulose/agar plates containing 15–45 mM 2-deoxy-D-glucose. These mutants were again screened for resistance to catabolite repression by glycerol or glucose on Walseth’s cellulose/agar
plates containing 50 g/l glycerol or 50 g/l glucose respectively. Four mutants with different sizes of clearing zone on Walseth’s
cellulose/agar plates containing 50 g/l glucose were selected for flask culture. Among them, the mutant NTUV-45-4 showed better
carboxymethylcellulase activity in flask culture containing 1% Avicel plus 3% glucose than did the parental strain.
Received: 9 October 1995/Received revision: 27 November 1995/Accepted: 8 January 1996 相似文献
5.
Rojas-Rejn Oscar A. Poggi-Varaldo Hctor M. Ramos-Valdivia Ana C. Martnez-Jimnez Alfredo Cristiani-Urbina Eliseo de la Torre Martnez Mayra Ponce-Noyola Teresa 《Journal of industrial microbiology & biotechnology》2011,38(1):257-264
Derepressed mutant PR-22 was obtained by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) mutagenic treatment of Cellulomonas flavigena PN-120. This mutant improved its xylanolytic activity from 26.9 to 40 U mg−1 and cellulolytic activity from 1.9 to 4 U mg−1; this represented rates almost 2 and 1.5 times higher, respectively, compared to its parent strain growing in sugarcane bagasse.
Either glucose or cellobiose was added to cultures of C. flavigena PN-120 and mutant PR-22 induced with sugarcane bagasse in batch culture. The inhibitory effect of glucose on xylanase activity
was more noticeable for parent strain PN-120 than for mutant PR-22. When 20 mM glucose was added, the xylanolytic activity
decreased 41% compared to the culture grown without glucose in mutant PR-22, whereas in the PN-120 strain the xylanolytic
activity decreased by 49% at the same conditions compared to its own control. Addition of 10 and 15 mM of glucose did not
adversely affect CMCase activity in PR-22, but glucose at 20 mM inhibited the enzymatic activity by 28%. The CMCase activity
of the PN-120 strain was more sensitive to glucose than PR-22, with a reduction of CMCase activity in the range of 20–32%.
Cellobiose had a more significant effect on xylanase and CMCase activities than glucose did in the mutant PR-22 and parent
strain. Nevertheless, the activities under both conditions were always higher in the mutant PR-22 than in the PN-120 strain.
Enzymatic saccharification experiments showed that it is possible to accumulate up to 10 g l−1 of total soluble sugars from pretreated sugarcane bagasse with the concentrated enzymatic crude extract from mutant PR-22. 相似文献
6.
The biochemical effects of technetium-99 as pertechnetate (TcO(4) (-)) were investigated in a variety of microorganisms (a nonsulfur purple bacterium, five blue-green algae, a protozoan, a diatom, two heterotrophic bacteria, a red alga and two green algae). Sensitivity to pertechnetate as measured by growth ranged from marked inhibition at 1 mug Tc/ml (nonsulfur purple bacterium) to no effect at 600 mug Tc ml (both green algae). No correlation between organism type and growth susceptibility to pertechnetate was apparent. The blue-green alga, Agmenellum quadruplicatum strain PR-6, bound technetium-99 to a level of 3 mug/mg dry weight cells (from medium containing 1.5 mm pertechnetate) in the light, but little or none in the dark; cell death occurred only with uptake. Addition of TcO(4) (-) to the medium caused a rapid but temporary increase in ATP levels of PR-6 (in the light only) and Tetrahymena pyriformis strain WH14. Respiration of organisms WH14 and Bacillus subtilis and photosynthesis of organism PR-6 were immediately slowed by the introduction of pertechnetate. Technetium as pertechnetate has a possible biochemical effect on cells, unrelated to its radioactivity or to a general oxidation effect. 相似文献
7.
A mosquitocidal cyanobacterium has been developed by introducing the mosquito-toxic cryIVD gene from Bacillus thuringiensis subsp. israelensis into the unicellular cyanobacterium Agmenellum quadruplicatum PR-6 (Synechococcus sp. strain PCC 7002). The cryIVD gene was introduced into the cyanobacterium on a derivative of the PR-6 expression vector pAQE19 delta Sal in which the cryIVD gene was translationally fused to the initial coding sequence of the highly expressed PR-6 cpcB gene. Coomassie blue staining and immunoblot analysis of gel-fractionated cell extract polypeptides indicate that the cpcB-cryIVD gene fusion is expressed at high levels in the cyanobacterial cells, with little or no apparent degradation of the cryIVD gene product. Larvicidal assays revealed that freshly hatched Culex pipiens mosquito larvae readily ingested the transformed cyanobacteria and that the cells proved to be toxic to the larvae. 相似文献
8.
Novel change in the carbohydrate portion of Myxococcus xanthus lipopolysaccharide during development. 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have examined the alterations in lipopolysaccharide during aggregation and early development in Myxococcus xanthus. The lipopolysaccharide was isolated and characterized from cells developing on agar during glycerol induction and vegetative growth. A methylated amino sugar was identified as 6-O-methylgalactosamine by gas-liquid chromatography-mass spectrometry. This novel sugar was enriched in cells developing on agar. 相似文献
9.
Surface Attachment Induced Production of Antimicrobial Compounds by Marine Epiphytic Bacteria Using Modified Roller Bottle Cultivation 总被引:1,自引:0,他引:1
A modified roller bottle culture method elicited the production of antimicrobial compounds from 2 epibiotic marine bacterial
strains, EI-34-6 and II-111-5, isolated from the surface of the marine alga Palmaria palmata. These isolates, tentatively
identified as Bacillus species, were grown as a biofilm on the surface of nutrient glycerol ferric agar (NGFA) and marine
Columbia glycerol agar (MCGA) on the inside of a rolling bottle. The biofilm was shown to be stable, and the cells were difficult
to remove from the agar surface. The culture supernatant exhibited a different antibiotic spectrum when the strains were grown
using the agar roller bottle method compared with shake flask cultures or nonagar roller bottle cultures. These results suggest
that biofilm formation is an important factor in the production of antimicrobial compounds by these 2 strains, and roller
bottle cultivation also allowed production of these compounds to be increased. The methodology used here has the potential
to allow increased production of useful secondary metabolites such as antibiotics from marine epibiotic bacteria. 相似文献
10.
Cloning and expression of the cryIVD gene of Bacillus thuringiensis subsp. israelensis in the cyanobacterium Agmenellum quadruplicatum PR-6 and its resulting larvicidal activity. 总被引:10,自引:4,他引:6
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A mosquitocidal cyanobacterium has been developed by introducing the mosquito-toxic cryIVD gene from Bacillus thuringiensis subsp. israelensis into the unicellular cyanobacterium Agmenellum quadruplicatum PR-6 (Synechococcus sp. strain PCC 7002). The cryIVD gene was introduced into the cyanobacterium on a derivative of the PR-6 expression vector pAQE19 delta Sal in which the cryIVD gene was translationally fused to the initial coding sequence of the highly expressed PR-6 cpcB gene. Coomassie blue staining and immunoblot analysis of gel-fractionated cell extract polypeptides indicate that the cpcB-cryIVD gene fusion is expressed at high levels in the cyanobacterial cells, with little or no apparent degradation of the cryIVD gene product. Larvicidal assays revealed that freshly hatched Culex pipiens mosquito larvae readily ingested the transformed cyanobacteria and that the cells proved to be toxic to the larvae. 相似文献
11.
Agmenellum quadruplicatum strain PR-6 and Oscillatoria sp. strain JCM grown photoautotrophically in the presence of aniline metabolized the aromatic amine to formanilide, acetanilide and p-aminophenol. The metabolites were isolated by either thin-layer, gas-liquid or high pressure liquid chromatography and identified by comparison of their chromatographic, ultraviolet absorbance and mass spectral properties with those of authentic compounds. The toxicity of aniline derivatives towards Agmenellum quadruplicatum strain PR-6 indicated that the cyanobacterium was extremely sensitive to o-, m- and p-aminophenols, and phenylhydroxylamine.Abbreviations TLC
thin layer chromatography
- HPLC
high pressure liquid chromatography
- GC/MS
gas chromatography/mass spectrometry
- m/e
mass to charge ratio 相似文献
12.
Glycerol kinase activity and glycerol utilization by rat granular pneumocytes were determined in order to investigate the rate-limiting step for glycerol incorporation into lung lipids. Granular pneumocytes were isolated in primary culture following trypsinization of rat lungs. Glycerol kinase activity was 8.2 nmol/h per 10(6) cells. Incorporation of [1,3-14C]glycerol into total cell lipids was 0.29 nmol/h per 10(6) cells. In the presence of saturating glycerol concentration, production of 3H2O from [2-3H]glycerol was 13 times greater than incorporation of [14C]glycerol into lipids. Glycerol phosphate dehydrogenase activity in isolated cells was approximately 10 times glycerol kinase activity. In the presence of 5.6 mM glucose, glycerol incorporation into lipids was decreased 79% and detritiation of glycerol was decreased 34%. This effect of glucose was due to a 25% increase in cell glycerol 3-phosphate content, resulting in dilution of the precursor pool and possible inhibition of glycerol phosphorylation. These results indicate that the relatively limited incorporation of glycerol into surfactant phospholipids by lung epithelial cells reflects the relatively high rate of glycerol 3-phosphate oxidation. 相似文献
13.
S. Edward Stevens Jr Randy C. Murphy William J. Lamoreaux Lewis B. Coons 《Journal of applied phycology》1994,6(2):187-197
Larvae of the mosquitoAedes aegypti ingested, and developed into adults, on a diet of 1O of 14 different species of cyanobacteria includingAgmenellum quadruplicatum PR-6 (=Synechococcus PCC7002). Mosquito larvae ingested and grew on cells of PR-6 adapted to growth in the absence of NaCl. ThecryIVD gene ofBacillus thuringiensis var.israelensis was cloned into a PR-6 expression vector to form pAQRM56, which was transformed into PR-6. Expression of the CryIVD protein in PR-6 was demonstrated by immunocytochemistry and larvicidal activity. Immunogold labelling indicated production of an electron-dense material among the thylakoid membranes of PR-6. Cells of PR-6 carrying pAQRM56 were toxic to the larvae ofA. aeqypti whereas control cells were not. Growth of PR-6 cells carrying pAQRM56 was slower than the growth of control cells and these cells were also larger. 相似文献
14.
Santiago Llovera Ramon Bonet Maria D. Simon-Pujol Francisco Congregado 《Applied microbiology》1993,59(10):3516-3518
Resting cells of Agrobacterium radiobacter EPS-916 grown on glucose, fructose, maltose, lactose, mannitol, or glycerol reduced 0.5 mM chromate. However, resting cells of strain EPS-916 grown on glutamate or succinate did not reduce chromate. The ability of washed cells to reduce chromate was correlated with their redox potential. 相似文献
15.
Ribonucleotide (cytidine 5'-diphosphate) reductase activity can be detected in situ in cells of the blue-green alga Agmenellum quadruplicatum, strain PR-6, after the cells are made permeable by treatment with ether. The Agmenellum reductase resembles the enzyme from Escherichia coli. 相似文献
16.
Calcium-labile mitotic spindles isolated from sea urchin eggs (Lytechinus variegatus) 总被引:27,自引:22,他引:5
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
《The Journal of cell biology》1980,86(2):355-365
We isolated calcium-labile mitotic spindles from eggs of the sea urchin Lytechinus variegatus, using a low ionic strength, EGTA lysis buffer that contined 5.0 mM EGTA, 0.5 mM MgCl2, 10-50 mM PIPES, pH 6.8, with 1% Nonidet P-40 (detergent) and 20-25% glycerol. Isolated spindles were stored in EGTA buffer with 50% glycerol for 5-6 wk without deterioration. The isolated spindles were composed primarily of microtubules with the chromosomes attached. No membranes were seen. Isolated spindles, perfused with EGTA buffer to remove the detergent and glycerol, had essentially the same birefringent retardation (BR) as spindles in vivo at the same mitotic stage. Even in the absence of glycerol and exogenous tubulin, the isolated spindles were relatively stable in the EGTA buffer: BR decayed slowly to about half the initial value within 30-45 min. However, both the rate and extent of BR decay increased with concentrations of Ca2+ above 0.2-0.5 muM as assayed using Ca-EGTA buffers (0.2 mM EGTA, 0.5 mM MgCl2, 50 mM PIPES, pH 6.8, plus various amounts of CaCl2). Microtubules depolymerized almost completely in < 6 min at Ca2+ concentrations of 2 muM and within several seconds at 10 muM Ca2+. Of several divalent cations tested, only Sr2+ caused comparable changes in BR. The absence of membranes in the isolated spindles appeared to be associated with a lack of calcium- sequestering ability. Our results suggest that calcium ions play an important role in the depolymerization of spindle microtubules and that membrane components may function within the mitotic apparatus of living cells to sequester and release calcium ions during mitosis. 相似文献
17.
Kumar V Sankaranarayanan M Jae KE Durgapal M Ashok S Ko Y Sarkar R Park S 《Applied microbiology and biotechnology》2012,96(2):373-383
The co-production of 3-hydroxypropionic acid (3HP) and 1,3-propanediol (PDO) from glycerol was studied using the resting cells of a recombinant Klebsiella pneumoniae J2B strain that overexpresses an aldehyde dehydrogenase (KGSADH). Active biomass was produced in a mineral salt medium containing yeast extract and glycerol under a range of aeration conditions, and shifted to potassium phosphate buffer containing glycerol for bioconversion. The microaerobic or anaerobic conditions were favorable for both the production of active biomass and subsequent bioconversion. At the flask level, the recombinant strain (2.0?g?CDW/L) grown under microaerobic conditions produced 43.2?mM 3HP and 59.0?mM PDO from glycerol (117?mM) in 30?min with a cumulative yield of 0.87?(mol/mol). The fed-batch bioconversion, which was performed in a 1.5-L bioreactor with 1.0?g?CDW/L at a constant pH?7.0 under anaerobic conditions, resulted in 125.6?mM 3HP and 209.5?mM PDO in 12?h with a cumulative overall productivity, yield, and maximum specific production rate of 27.9?mmol/L/h, 0.71 (mol/mol), and 128.5?mmol/g CDW/h, respectively. Lactate, succinate and 2,3-butanediol were the major by-products, whereas the production of acetate and ethanol was marginal. This is the first report of the simultaneous production of 3HP and PDO from glycerol using a resting cell system. 相似文献
18.
Control of glucose metabolism in isolated acini of the lactating mammary gland of the rat. The ability of glycerol to mimic some of the effects of insulin. 总被引:10,自引:9,他引:1
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Inhibition of glucose uptake by acetoacetate and relief of this inhibition by insulin found previously in slices of rat mammary gland [Williamson, McKeown & Ilic (1975) Biochem. J. 150. 145-152] was confirmed in acini, which represent a more homogeneous population of cells. Glycerol (1mM) behaved like insulin (50 minuits/ml) in its ability to relieve the inhibition of glucose (5 mM) utilization caused by acetoacetate (2 mM) in acini. Both glycerol and insulin reversed the increase in [citrate] and the decrease in [glycerol 3-phosphate] and the [lactate]/[pyruvate] ratio in the presence of acetoacetate. Lipogenesis from 3H2O, [3-14C] acetoacetate, [1-14C]- and [6-14C]-glucose was stimulated, whereas 14CO2 formation from [3-14C]acetoacetate was decreased. Neither insulin nor glycerol relieved the acetoacetate inhibition of glucose uptake when lipogenesis was inhibited by 5-(tetradecyloxy)-2-furoic acid. From measurements of [3-14C]acetoacetate incorporation into lipid in the various situations it is suggested that a cytosolic pathway for acetoacetate utilization may exist in rat mammary gland. In the absence of acetoacetate, glycerol inhibited glucose utilization by 60% and increased both [glycerol 3-phosphate] and the [lactate/[pyruvate] ratio. Possible ways in which glycerol may mimic the effects of insulin are discussed. 相似文献
19.
Multiple resistance and biochemical mechanisms of pyridaben resistance in Tetranychus urticae (Acari: Tetranychidae) 总被引:3,自引:0,他引:3
A field colony of Tetranychus urticae (Koch) (Acari: Tetranychidae) resistant to pyridaben was selected with pyridaben successively for 20 generations to produce the PR-20 strain. Resistance and multiple resistance levels of the PR-20 strain to 15 acaricides were determined using a spray bioassay. The PR-20 strain was extremely resistant to pyridaben (resistance ratio [RR] = 240]. The strain exhibited extremely strong resistance to fenpyroximate (RR=373) and acrinathrin (RR=329) and strong resistance to benzoximate (RR=84). An RR = 10-40 was observed with abamectin, fenazaquin, fenbutatin oxide, fenpropathrin, and tebufenpyrad. The PR-20 strain showed low levels of resistance (RR <10) to azocyclotin, bromopropylate, chlorfenapyr, dicofol, milbemectin, and propargite. Synergist experiments with different metabolic inhibitors revealed that piperonyl butoxide (PBO), a mixed function oxidase (MFO) inhibitor, had the greatest effect on pyridaben resistance. PBO significantly caused pyridaben resistance in the PR-20 strain to drop to the full susceptibility level of the susceptible (S) strain. However, there was no significant difference in MFO activities measured using a model substrate between the S and PR-20 strains. These results suggest that use of certain acaricides with little multiple resistance or PBO will be useful for the management of pyridaben resistance in the field. 相似文献
20.
Etemadifar Z Emtiazi G 《Zeitschrift für Naturforschung. C, Journal of biosciences》2008,63(7-8):599-604
Gasoline-contaminated soil from Isfahan, Iran was selected to isolate a bacterium capable of desulfurizing dibenzothiophene (DBT). The isolated strain was named R1 and identified as Rhodococcus erythropolis through biochemical tests as well as sequencing of 16S rRNA gene. This strain could efficiently produce 2-hydroxybiphenyl (HBP) from DBT via the 4S metabolic pathway. The highest HBP amount was produced at 2 mM DBT with addition of glucose (10 g l(-1)), ethanol (3 g l(-1)), glycerol (2 g l(-1)) or succinate (10 g l(-1)) as carbon sources at pH 7. Highest respiration and growth rates were observed by microplate titration on 0.1 mM HBP, and addition of 0.2 mM HBP to glucose (1 g l(-1)) and DBT (0.3 mM) could inhibite the respiration of the isolate. The isolated strain could grow up to 0.4 mM of HBP when it is used with mineral sulfur as sole sulfur source. To the best of our knowledge this is the first report on a microtiter assay for the production and utilization of HBP by Rhodococcus. 相似文献