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1.
Summary The instability of Lac+ and Cit+ phenotypes was investigated inLeuconostoc
mesenteroides subsp.cremoris ATCC 19245 and in four strains ofLeuconostoc
mesenteroides subsp.dextranicum. The two phenotypes were linked respectively to a 14 Mdal and a 34 Mdal plasmid in Leuconostoc mesenteroides subsp.cremoris ATCC 19245. InLeuconostoc
mesenteroides subsp.dextranicum the character Lac+ was linked to a 28 Mdal plasmid, while the Cit+ phenotype was stable. 相似文献
2.
J J Diwan 《Biochemical and biophysical research communications》1973,50(2):384-391
The energy-linked flux of K+ into rat liver mitochondria is found to be stimulated by the sulfhydryl reagent, N-ethyl maleimide. The stimulation of K+ influx by N-ethyl maleimide is observed only at alkaline external pH. N-ethyl maleimide also stimulates efflux of K+ from the mitochondria. The stimulation by N-ethyl maleimide of K+ influx, but not K+ efflux, is dependent on the availability of metabolic energy. It is suggested that the effect of N-ethyl maleimide on K+ influx may be secondarily the result of an inhibition of phosphate-hydroxyl exchange. The dependence of energy-linked K+ influx on the external pH may be interpreted as evidence for a role of OH? as a counterion accompanying K+ through the mitochondrial pump mechanism. 相似文献
3.
Summary
Ankistrodesmus braunii and Chlorella vulgaris were cultured heterotrophically under various operating conditions. The maximum rate of biomass production was 900 and 900 mg L-1 d-1 by C. vulgaris and 1000 and 700 mg L-1 d-1 by A. braunii in the light and dark, respectively. This indicates that these algae could produce in excess of 1530 dry weight tonnes ha-1 y-1 which is 10–20 times higher than the maximum production levels in the literature. 相似文献
4.
D. R. Modi A. K. Singh K. S. Rao D. Chakravarty H. N. singh 《Biotechnology letters》1991,13(11):793-798
Summary Machete resistant (Mat
r), basalin resistant (Bas
r), 3(3,4 dichlorophenyl)-1,1-dimethyl urea resistant (DCMU
r), atrazine resistant (Atr
r) and propanil resistant (Prp
r) phenotypes ofGloeocapsa sp. were cotransformed toNostoc
muscorum at high frequency. Spontaneously occurring mutants of the multiple herbicide resistant transformant containing L-methionine-DL-sulfoximine resistant (Msx
r), ethylene diamine resistant (Eda
r), or phosphinothricin resistant (Ppt
r) glutamine synthetase (GS) showed extracellular liberation of ammonia resulting from fixation of N2 under photosynthetic conditions. Results suggest a definite role of GS activity in regulation of extracellular ammonia. 相似文献
5.
G-matrix FT projection NMR spectroscopy was employed for resonance assignment of the 79-residue subunit c of the Escherichia coli F1F0 ATP synthase embedded in micelles formed by lyso palmitoyl phosphatidyl glycerol (LPPG). Five GFT NMR experiments, that is,
(3,2)D HNNCO, L-(4,3)D HNNC
αβ
C
α, L-(4,3)D HNN(CO)C
αβ
C
α, (4,2)D HACA(CO)NHN and (4,3)D HCCH, were acquired along with simultaneous 3D 15N, 13Caliphatic, 13Caromatic-resolved [1H,1H]-NOESY with a total measurement time of ∼43 h. Data analysis resulted in sequence specific assignments for all routinely
measured backbone and 13Cβ shifts, and for 97% of the side chain shifts. Moreover, the use of two G2FT NMR experiments, that is, (5,3)D HN{N,CO}{C
αβ
C
α} and (5,3)D {C
αβ
C
α}{CON}HN, was explored to break the very high chemical shift degeneracy typically encountered for membrane proteins. It is shown
that the 4D and 5D spectral information obtained rapidly from GFT and G2FT NMR experiments enables one to efficiently obtain (nearly) complete resonance assignments of membrane proteins.
Qi Zhang, Hanudatta S. Atreya, Douglas E. Kamen, Mark E. Girvin and Thomas Szyperski—New York Consortium on Membrane Protein
Structure. 相似文献
6.
Summary Genetic determinants of the Muc+ character were investigated in two ropy strains,Lactobacillus delbrueckii ssp.bulgaricus 201 andL. casei ssp.casei NCIB 4114, which secrete a large amount of slime in culture media. Plasmid DNA analysis revealed the presence of two plasmids (4.5 and 2.3 Mdal) inL. casei ssp.casei, whileL. delbrueckii ssp.bulgaricus was plasmid free, suggesting a chromosomal location of Muc+ character in this strain. Curing experiments carried out onL. casei ssp.casei NCIB 4114 indicated a correlation between the Muc+ phenotype and the 4.5 Mdal plasmid. 相似文献
7.
Summary ExposingBacillus
subtilis cultures to high concentrations of alkali cations, especially K+, allows efficient transformation by plasmids. The method allows transformation with unfractionated plasmid DNA, monomeric plasmid DNA as well as linear plasmid DNA.B.
subtilis strains, not amenable to natural transformation, were also transformed by the present method. 相似文献
8.
K. Nils-Gunnar Johansson Tyge Greibrokk Bruce L. Currie Jan Hansen Karl Folkers Cyril Y. Bowers 《Biochemical and biophysical research communications》1975,63(1):62-68
Mutants of the nitrogen-fixing blue-green alga Nostocmuscorum have been isolated which do not fix nitrogen or reduce acetylene, and which are resistant to streptomycin (1000 μg ml?1). One such mutant (nif-st-R) was crossed with the wild-type nitrogen-fixing streptomycin-sensitive parent (nif+st-S) and under conditions which counterselected the latter, recombinants (nif+st-R) were obtained at a frequency of up to 4.6 in 105 colonies. The frequency of spontaneous mutations or revertants of each parent growing alone was 1 in 107 or less. The higher yield of new genotypes from mixed cultures is interpreted as evidence of nif gene transfer in Nostocmuscorum. 相似文献
9.
T Takabe M Nishimura T Akazawa 《Biochemical and biophysical research communications》1976,68(2):537-544
Ribulose-1,5-bisphosphate car?ylase (E.C. 4.1.1.39) from 2 blue-green algae, Plectonema boryanum and Anabaena variabilis, was isolated by sucrose density gradient centrifugation. Both enzymes had a sedimentation value of about 18s, similar to that of Chromatium enzyme. The presence of two subunits (A, B) in the algal enzyme was demonstrated by Nadodecyl sulfate polyacrylamide gel electrophoresis. The molecular weight of the two subunits was determined: for Plectonema A, 5.4 × 104 and B, 1.3 × 104 and Anabaena A, 5.2 × 104 and B, 1.3 × 104, respectively. The car?ylase reaction catalysed by the algal enzyme was similar to the higher plant enzyme in exhibiting the Mg2+-effect, the optimal pH shifting from alkaline to neutral by elevating the concentration of Mg2+ in the assay mixture. The rabbit antisera developed against the spinach ribulose-1,5-bisphosphate car?ylase and its catalytic oligomer exhibited significant inhibitory effects on the car?ylation reaction catalysed by the algal enzyme. 相似文献
10.
In the Azolla-Anabaena azollae symbiotic system, Anabaena akinetes get entrapped between the indusium and the apical cap of the megaspore apparatus during megasporocarp development, thus maintaining the continuity of the cyanobacterial association throughout the life cycle of the fern. The entrapped akinetes serve as the source of inoculum for infecting the new sporophyte when it is emerging from the megaspore apparatus. A procedure to generate Anabaena-free Azolla was developed by fertilizing the germinating megasporocarps in which the indusium along with the akinetes were removed by micromanipulation. This method has the advantage of not requiring drastic treatments of Azolla with antibiotics to eliminate the endosymbiotic cyanobacterial cells. Details of this new method and its usefulness in studies aimed at recombination of Azolla with Anabaena azollae are discussed.Abbreviations IRRI
International Rice Research Institute
- I–
IRRI medium devoid of combined nitrogen
- I+
IRRI medium containing combined nitrogen
- SDS
sodium dodecyl sulfate 相似文献
11.
Claude P. Champagne 《Biotechnology letters》1990,12(10):771-776
Summary Cells ofLactococcus
lactis orLactobacillus
helveticus were immobilized in calcium-alginate beads, added to raw milk, and incubated 48 h at 7°C. The addition of 2.7×107 immobilizedLc.lactis or 13×107 immobilizedLb.
helveticus cells per mL reduced the development of the psychrotrophic bacteria of raw milk by approximately 50%. The pH of the raw milk dropped 0.10 to 0.22 units under these conditions. Periodic agitation of the seeded raw milk increased the inhibitory activity of the immobilized lactic acid bacteria (LAB). Free LAB cells in the system were only of 0.5% of total LAB. The use of immobilized LAB to inhibit psychrotrophic bacteria might be extended to raw milks destined to the manufacture of non-fermented dairy products. 相似文献
12.
The Neuronal Kv4 Channel Complex 总被引:1,自引:0,他引:1
Covarrubias M Bhattacharji A De Santiago-Castillo JA Dougherty K Kaulin YA Na-Phuket TR Wang G 《Neurochemical research》2008,33(8):1558-1567
Kv4 channel complexes mediate the neuronal somatodendritic A-type K+ current (ISA), which plays pivotal roles in dendritic signal integration. These complexes are composed of pore-forming voltage-gated α-subunits
(Shal/Kv4) and at least two classes of auxiliary β-subunits: KChIPs (K
+-Channel-Interacting-Proteins) and DPLPs (Dipeptidyl-Peptidase-Like-Proteins). Here, we review our investigations of Kv4 gating mechanisms and functional remodeling by specific auxiliary β-subunits.
Namely, we have concluded that: (1) the Kv4 channel complex employs novel alternative mechanisms of closed-state inactivation;
(2) the intracellular Zn2+ site in the T1 domain undergoes a conformational change tightly coupled to voltage-dependent gating and is targeted by nitrosative
modulation; and (3) discrete and specific interactions mediate the effects of KChIPs and DPLPs on activation, inactivation
and permeation of Kv4 channels. These studies are shedding new light on the molecular bases of ISA function and regulation.
Special issue article in honor of Dr. Ricardo Tapia. 相似文献
13.
Azurmendi HF Mitra S Ayala I Li L Finkielstein CV Capelluto DG 《Molecules and cells》2010,30(6):581-585
The Toll-interacting protein (Tollip) is a negative regulator of the Toll-like receptor (TLR)-mediated inflammation response.
Tollip is a modular protein that contains an Nterminal Tom1-binding domain (TBD), a central conserved domain 2 (C2), and a C-terminal coupling of ubiquitin to endoplasmic reticulum degradation (CUE) domain. Here, we report the sequence-specific backbone 1H, 15N, and 13C assignments of the human Tollip CUE domain. The CUE domain was found to be a stable dimer as determined by size-exclusion
chromatography and molecular crosslinking studies. Analysis of the backbone chemical shift data indicated that the CUE domain
exhibits three helical elements corresponding to 52% of the protein backbone. Circular dichroism spectrum analysis confirmed
the helical nature of this domain. Comparison of the location of these helical regions with those reported for yeast CUE domains
suggest differences in length for all helical elements. We expect the structural analysis presented here will be the foundation
for future studies on the biological significance of the Tollip CUE domain, its molecular interactions, and the mechanisms
that modulate its function during the inflammatory response. 相似文献
14.
Summary Two thermophilic strains of Lactobacillus were transformed by electroporation; L.fermentum with a maximum of frequency of 1×105/ug of plasmid vector pPSC20DNA and 1.4×103/ug pSA3DNA. L.helveticus showed a very low frequency of transformation, from 9 to 26 transformants/ug DNA in all the experiments carried out with both the vectors. While L.fermentum transformants were very stable, in L.helveticus the acquired plasmid was lost after 30–50 generations. 相似文献
15.
A method was developed for the transformation of the ethanol-producing thermophilic bacteriumClostridium
thermohydrosulfuricum DSM 568 without protoplast formation. Competence for DNA uptake was induced by treatment ofCl.
thermohydrosulfuricum cells with 50 mM Tris-HCl pH 8. 3. In the presence of polyethylene glycol (PEG 6000) the Tris-treated cells were transformed with the antibiotic resistance plasmids pUB110 (KmR) and pGS13 (KmR CmR) at frequencies of 4×10–6 per viable cell. This transformation method will be useful for the development of genetic exchange systems in thermophilic clostridia of biotechnological interest. 相似文献
16.
Spheroplasts of Agrobacterium tumefaciens strains and E. coli were fused with protoplasts of Nicotiana tabacum. Fusion products were cultured in the presence of antibiotics to eliminate remaining bacterial spheroplasts. On hormone free medium, tobacco protoplasts treated with wild type Agrobacterium-strains formed colonies with an average frequency of 10–4. Opine synthesis was detected in the tissues. Some calli derived from protoplasts treated with A. tumefaciens C58C1pRi15834 formed typical hairy roots. Kanamycin resistant calli were obtained after fusion with A. tumefaciens containing pLGVTi23 neo (frequency=10–3). Fusion of E. coli spheroplasts containing a virulent pTiB6S3::RP4 co-integrate with tobacco protoplasts yielded two hormone independent growing calli producing octopine out of 105 microcalli.Abbreviations PEG
Polyethylene glycol
- PVA
Polyvinyl alcohol 相似文献
17.
Kazuo Kamaike Yoshihiro Hasegawa Yoshiharu Ishido 《Nucleosides, nucleotides & nucleic acids》2013,32(1):37-43
Abstract 3′,5′-Di-O-benzoyl-2′-O-(tetrahydropyran-2-yl)uridine and 3′,5′ -di-O-benzoyl-N 2-isobutyryl-2′-O-(tetrahydropyran-2-yl)guanosine are converted into-N 3-anisoyl-2′-O-(tetrahydropyran-2-yl)uridine (less and more polar diastereoisomers in 37% and 42% yields, respectively) and O 6-diphenyl carbamoylN 2-isobutyryl-2′-O-(tetrahydropyran-2-yl)- guanosine (less and more polar diastereoisomers in 15% and 59% yields, respectively), respectively, by N 3-anisoylation and O 6-diphenylcarbamoylation, followed by 3′,5′-di-O-debenzoylation. 相似文献
18.
Direct somatic embryogenesis on immature zygotic embryos in vitro has been confirmed for Trifolium pratense and extended to T. resupinatum and T. subterraneum. For all species direct embryo cloning can be achieved on an appropriate basal medium supplemented with 1gl–1 yeast extract and 0.05 mgl–1 BAP. Basal medium/sucrose formulation, level of yeast extract and level of BAP affected the nature of in vitro responses. In particular, for T. pratense and T. subterraneum lowering of the yeast extract level suppressed embryoid initiation, and raising of the BAP level stimulated formation of nodular morphogenic callus. For T. resupinatum alteration of the basal medium/sucrose formulation changed the tissue site of embryoid initiation from hypocotyl to cotyledons or both. Control of embryoid initiation is briefly discussed.Abbreviation BAP
6-benzylaminopurine 相似文献
19.
Garima Jaipuria Anushikha Thakur Hanudatta S. Atreya 《Journal of biomolecular NMR》2010,48(3):137-145
Three-dimensional (3D) structure determination of proteins is benefitted by long-range distance constraints comprising the
methyl groups, which constitute the hydrophobic core of proteins. However, in methyl groups (of Ala, Ile, Leu, Met, Thr and
Val) there is a significant overlap of 13C and 1H chemical shifts. Such overlap can be resolved using the recently proposed (3,2)D HCCH-COSY, a G-matrix Fourier transform (GFT) NMR based experiment, which facilitates editing of methyl groups into distinct
spectral regions by combining their 13C chemical shifts with that of the neighboring, directly attached, 13C nucleus. Using this principle, we present three GFT experiments: (a) (4,3)D NOESY-HCCH, (b) (4,3)D 1H-TOCSY-HCCH and (c) (4,3)D 13C-TOCSY-HCCH. These experiments provide unique 4D spectral information rapidly with high sensitivity and resolution for side-chain resonance
assignments and NOE analysis of methyl groups. This is exemplified by (4,3)D NOESY-HCCH data acquired for 17.9 kDa non-deuterated cytosolic human J-protein co-chaperone, which provided crucial long-range distance
constraints for its 3D structure determination. 相似文献
20.
Olli H. Tuovinen Jaakko Puhakka Paula Hiltunen Katherine M. Dolan 《Biotechnology letters》1985,7(6):389-394
Summary Ferrous-ion oxidation byThiobacillus
ferrooxidans was inhibited by 10–6 M Ag+ while a slight inhibition of growth was apparent with 10–7 M Ag+. The threshold toxic concentration was the seme for four different test strains. While prolonged lag phases resulted from culture exposure to Ag+, Fe2+ oxidation rates after the onset of growth showed little variation under these conditions. Yeast extract (0.02%) partially alleviated the toxicity of silver-ion by reducing the lag periods. Pyrite oxidation byT.
ferrooxidans and mixed cultures of acidophiles was tested at 8.3×10–7 to 8.3×10–5 M Ag+. Strong inhibition was apparent at 8.3×10–5 M Ag+ and little to no inhibition was observed at 8.3×10–7 M Ag+. 相似文献