Mineralization of [14C]octadecane by Acinetobacter calcoaceticus S19

1998 ◽  
Vol 44 (7) ◽  
pp. 681-686 ◽  
Author(s):  
Urmi Bajpai ◽  
R C Kuhad ◽  
Sunil Khanna
Keyword(s):  
Doubling Time ◽  
Acinetobacter Calcoaceticus ◽  
Octadecanoic Acid ◽  
Anaerobic Conditions ◽  
Whole Cells ◽  
Absolute Requirement

Uptake of octadecane by Acinetobacter calcoaceticus S19 was found to be 70% during growth (doubling time of 4 h), of which 60% was incorporated into the cells and 40% was oxidized to 14CO2. The ratio of [14C]octadecane uptake to its mineralization by whole cells was similar to that found during the growth of A. calcoaceticus S19. After 4 h of incubation of cells with [14C]octadecane, 44% was mineralized to 14CO2, while the rest remained associated with the cells. Octadecane uptake was not observed under anaerobic conditions, indicating an absolute requirement for oxygen. Acinetobacter calcoaceticus S19 converted octadecane to the corresponding octadecanol and octadecanoic acid; the corresponding aldehyde was not detected, however. Octadecanoic acid was partially degraded through β-oxidation to CO2 and partly assimilated as cell biomass.Key words: Acinetobacter calcoaceticus, octadecane uptake, mineralization.

Mineralization of [14C]octacosane by Acinetobacter calcoaceticus S30

1996 ◽  
Vol 42 (12) ◽  
pp. 1225-1231 ◽  
Author(s):  
Banwari Lal ◽  
Sunil Khanna
Keyword(s):  
Doubling Time ◽  
Acinetobacter Calcoaceticus ◽  
Metabolic Inhibitors ◽  
Acid Uptake ◽  
Sulphydryl Group ◽  
Whole Cells ◽  
Cell Biomass ◽  
Intermediate Metabolites ◽  
Transport Inhibitors ◽  
Energy Dependent

Acinetobacter calcoaceticus S30 could grow (doubling time, 7 h) on octacosane (C28) and degraded about 70% of the substrate during growth. Octacosanol, octacosanoic acid, and other lower carboxylic acids were identified during degradation of octacosane. Acinetobacter calcoaceticus S30 could also grow on intermediate metabolites, namely octacosanol and octacosanoic acid, although the doubling time was greater on octacosanoic acid (72 h on octacosanol and 120 h on octacosanoic acid). Whole cells of A. calcoaceticus S30 using [18-14C]octacosane mineralized 65% of the octacosane to 14CO2 and 30% of the radiolabel was retained in the cell biomass in 24 h. Acinetobacter calcoaceticus S30 converts octacosane to octacosanol through an oxidation step, which is then oxidized to octacosanoic acid and then β-oxidized to CO2. Among several metabolic inhibitors, those of the sulphydryl group greatly inhibited the uptake of octacosanol and octacosanoic acid at much lower concentrations. The electron transport inhibitors were potent inhibitors of octacosane, octacosanol, and octacosanoic acid uptake, suggesting that the oxidation of these substrates is an energy-dependent process.Key words: Acinetobacter calcoaceticus, mineralization, octacosane, octacosanol, octacosanoic acid.

Characterization of squalene epoxidase activity from the dermatophyte Trichophyton rubrum and its inhibition by terbinafine and other antimycotic agents.

1996 ◽  
Vol 40 (2) ◽  
pp. 443-447 ◽  
Author(s):  
B Favre ◽  
N S Ryder
Keyword(s):  
Biochemical Characterization ◽  
Trichophyton Rubrum ◽  
Side Chain ◽  
Ergosterol Biosynthesis ◽  
Squalene Epoxidase ◽  
High Potency ◽  
Whole Cells ◽  
Absolute Requirement ◽  
Tertiary Amino

Squalene epoxidase (SE) is the primary target of the allylamine antimycotic agents terbinafine and naftifine and also of the thiocarbamates. Although all of these drugs are employed primarily in dermatological therapy, SE from dermatophyte fungi has not been previously investigated. We report here the biochemical characterization of SE activity from Trichophyton rubrum and the effects of terbinafine and other inhibitors. Microsomal SE activity from T. rubrum was not dependent on soluble cytoplasmic factors but had an absolute requirement for NADPH or NADH and was stimulated by flavin adenine dinucleotide. Kinetic analyses revealed that under optimal conditions the Km for squalene was 13 microM and its Vmax was 0.71 nmol/h/mg of protein. Terbinafine was the most potent inhibitor tested, with a 50% inhibitory concentration (IC50) of 15.8 nM. This inhibition was noncompetitive with regard to the substrate squalene. A structure-activity relationship study with some analogs of terbinafine indicated that the tertiary amino structure of terbinafine was crucial for its high potency, as well as the tert-alkyl side chain. Naftifine had a lower potency (IC50, 114.6 nM) than terbinafine. Inhibition was also demonstrated by the thiocarbamates tolciclate (IC50, 28.0 nM) and tolnaftate (IC50, 51.5 nM). Interestingly, the morpholine amorolfine also displayed a weak but significant effect (IC50, 30 microM). T. rubrum SE was only slightly more sensitive (approximately twofold) to terbinafine inhibition than was the Candida albicans enzyme. Therefore, this difference cannot fully explain the much higher susceptibility (> or = 100-fold) of dermatophytes than of yeasts to this drug. The sensitivity to terbinafine of ergosterol biosynthesis in whole cells of T. rubrum (IC50, 1.5 nM) is 10-fold higher than that of SE activity, suggesting that the drug accumulates in the fungus.

Inactivation and Reactivation of the Hydrogenases of the Green Algae Scenedesmus obliquus and Chlamydomonas reinhardtii

1993 ◽  
Vol 48 (1-2) ◽  
pp. 41-45 ◽  
Author(s):  
Thomas Urbig ◽  
Rüdiger Schulz ◽  
Horst Senger
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Green Algae ◽  
Scenedesmus Obliquus ◽  
Sodium Dithionite ◽  
Anaerobic Conditions ◽  
Whole Cells ◽  
Complete Inactivation

The hydrogenases of the green algae Scenedesmus obliquus and Chlamydomonas reinhardtii were activated under anaerobic conditions. Exposure of whole cells and cell-free homogenates to air lead to a complete inactivation of the hydrogenases. The inactivation in whole cells of Scenedesmus is faster than the inactivation of the cell-free homogenate. Inactivation of the hydrogenases could be reversed by anaerobic readaptation in whole cells. The inactivation of the hydrogenase in homogenates seems to be irreversible. Neither the removal of oxygen nor the addition of ATP, NAD(P)H, sodium dithionite, dithiothreitol, ferredoxin and thioredoxin to homogenates facilitated the reactivation of the hydrogenase. The occurrence of a hydrogenase regulating factor is discussed.

scholarly journals Magnesium protoporphyrin chelatase activity in Rhodopseudomonas spheroides. Studies with whole cells

1972 ◽  
Vol 127 (1) ◽  
pp. 97-106 ◽  
Author(s):  
A. Gorchein
Keyword(s):  
Protein Synthesis ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pure Oxygen ◽  
Low Oxygen ◽  
Anaerobic Conditions ◽  
Whole Cells ◽  
Partial Pressures ◽  
Deficient Medium ◽  
Rhodopseudomonas Spheroides

1. Whole cells of Rhodopseudomonas spheroides grown under semi-anaerobic conditions in the light incorporated magnesium into exogenous protoporphyrin when incubated with EDTA or the related chelators EGTA, N-(2-hydroxyethyl)-ethylenediamine-NN′N′- triacetate and trans-1,2-diaminocyclohexanetetra-acetate. 2. The reaction was demonstrated under anaerobic conditions in the light or at low oxygen partial pressure in the dark. Partial pressures of oxygen greater than 15% inhibited the reaction. 3. Cells grown under pure oxygen were completely inactive, but on adaptation to growth under low oxygen partial pressure (O2+N2, 5:95) the development of activity paralleled the synthesis of bacteriochlorophyll. 4. The reaction with normal cells did not require protein synthesis, but cells that had lost their activity by being illuminated in Mg2+-deficient medium did not recover it in the absence of protein synthesis. 5. The product of the reaction was magnesium protoporphyrin monomethyl ester. 6. Evidence is presented that insertion of magnesium is obligatorily coupled with methylation and it is concluded that the reaction is dependent on a multienzyme complex.

F0 Cysteine, bCys21, in the Escherichia coli ATP Synthase Is Involved in Regulation of Potassium Uptake and Molecular Hydrogen Production in Anaerobic Conditions

2002 ◽  
Vol 22 (3-4) ◽  
pp. 421-430 ◽  
Author(s):  
Nelli Mnatsakanyan ◽  
Karine Bagramyan ◽  
Anait Vassilian ◽  
Robert K. Nakamoto ◽  
Armen Trchounian
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Production ◽  
Atp Synthase ◽  
Molecular Hydrogen ◽  
Atp Hydrolysis ◽  
Membrane Vesicles ◽  
Anaerobic Conditions ◽  
Whole Cells ◽  
B Subunit ◽  
Hydrolysis Of

The single cysteine in the b subunit of the membranous F0 sector and the 19 cysteines in extramembranous F1 sector of the Escherichia coli ATP synthase were replaced by alanine. When cells were grown under anaerobic conditions on glucose, the kcat for ATP hydrolysis of membrane vesicles containing the bCys21Ala mutant enzyme, but not enzymes with other cysteine replacements, was lower, while ATP-driven H+ pumping was unchanged. However, the ATP-dependent increase in the number of accessible thiol groups in membrane vesicles was negated. Furthermore, K+ uptake and molecular hydrogen production by whole cells and protoplasts was greatly decreased. These results indicate a role for the F0 subunit bCys21 in the functionality of F0F1 and coupling to other membranous activities under fermentative conditions.

The separation and identification of the lipids of Rhodopseudomonas spheroides

1968 ◽  
Vol 170 (1020) ◽  
pp. 279-297 ◽  
Keyword(s):  
Phosphatidic Acid ◽  
Dry Weight ◽  
Detailed Examination ◽  
Subcellular Fractions ◽  
Anaerobic Conditions ◽  
Whole Cells ◽  
Rhodopseudomonas Spheroides ◽  
Micro Organisms

Detailed examination of the lipids of Rhodopseudomonas spheroides was undertaken since it was thought this might provide information on the biogenesis of the chromatophores. The phospholipids of purified chromatophores consist of phosphatidylethanolamine (35%), phosphatidylglycerol (34%) and phosphatidylcholine (23%); minor quantities of phosphatidic acid and of cardiolipin were also found. In addition, a sulpholipid was detected and also a new lipid containing ornithine. The relative proportions of the different phospholipids in chromatophores, in other subcellular fractions from pigmented micro-organisms and in fragments from cells grown under oxygen were similar. However, the ‘aerobic fragments’ contained much less ornithine lipid than the chromatophores. Comparison of the relative amounts of the different phospholipids in whole cells grown under oxygen, under air, or under semi-anaerobic conditions in the light showed no marked differences, the composition being similar to that found in chromatophores. It is concluded that there is no particular lipid specifically associated with chromatophores. Poly- β -hydroxybutyrate accounted for as much as 35% of the dry weight of cells grown under oxygen in the dark on malate-glutamate medium. It is necessary to remove this material before chromatography as it otherwise interferes with the separation.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Discovery of intracellular 2,8 dihydroxyadenine crystals in bovine lymphatic and hepatic cells

1987 ◽  
Vol 45 ◽  
pp. 906-907
Author(s):  
W. E. Rigsby ◽  
D. M. Hinton ◽  
V. J. Hurst ◽  
P. C. McCaskey
Keyword(s):  
Polarized Light ◽  
Paraffin Sections ◽  
Tissue Samples ◽  
Whole Cells ◽  
Tissue Sections ◽  
Hepatic Cells ◽  
Slaughter House ◽  
Mammalian Tissues ◽  
Carbon Coated ◽  
Cellular Components

Crystalline intracellular inclusions are rarely seen in mammalian tissues and are often difficult to positively identify. Lymph node and liver tissue samples were obtained from two cows which had been rejected at the slaughter house due to the abnormal appearance of these organs in the animals. The samples were fixed in formaldehyde and some of the fixed material was embedded in paraffin. Examination of the paraffin sections with polarized light microscopy revealed the presence of numerous crystals in both hepatic and lymph tissue sections. Tissue sections were then deparaffinized in xylene, mounted, carbon coated, and examined in a Phillips 505T SEM equipped with a Tracor Northern X-ray Energy Dispersive Spectroscopy (EDS) system. Crystals were obscured by cellular components and membranes so that EDS spectra were only obtainable from whole cells. Tissue samples which had been fixed but not paraffin-embedded were dehydrated, embedded in Spurrs plastic, and sectioned.

High-resolution nucleic acid sequence mapping via in situ hybridization at the Electron Microscope level

1995 ◽  
Vol 53 ◽  
pp. 752-753
Author(s):  
B.A. Hamkalo ◽  
S. Narayanswami ◽  
A.P. Kausch
Keyword(s):  
Nucleic Acid ◽  
Interphase Nucleus ◽  
Genome Mapping ◽  
Precise Location ◽  
Electron Microscope Level ◽  
Rna Sequences ◽  
Fundamental Interest ◽  
Whole Cells ◽  
Dna And Rna

The availability of nonradioactive methods to label nucleic acids an the resultant rapid and greater sensitivity of detection has catapulted the technique of in situ hybridization to become the method of choice to locate of specific DNA and RNA sequences on chromosomes and in whole cells in cytological preparations in many areas of biology. It is being applied to problems of fundamental interest to basic cell and molecular biologists such as the organization of the interphase nucleus in the context of putative functional domains; it is making major contributions to genome mapping efforts; and it is being applied to the analysis of clinical specimens. Although fluorescence detection of nucleic acid hybrids is routinely used, certain questions require greater resolution. For example, very closely linked sequences may not be separable using fluorescence; the precise location of sequences with respect to chromosome structures may be below the resolution of light microscopy(LM); and the relative positions of sequences on very small chromosomes may not be feasible.

Modified gach technique vs critical point drying: Shrinkage analysis for SEM

1987 ◽  
Vol 45 ◽  
pp. 954-955
Author(s):  
B. Thompson ◽  
N. Sculov ◽  
R.E. Crang
Keyword(s):  
Critical Point ◽  
Calf Serum ◽  
Drying Shrinkage ◽  
Specimen Preparation ◽  
Cell Shrinkage ◽  
Whole Cells ◽  
Critical Point Drying ◽  
Prepared Material ◽  
Inverted Microscope ◽  
Phosphate Buffered Saline

The use of co-polymerized glutaraldehyde-carbohydrazide (GACH) was proposed for specimen preparation in scanning electron microscopy (SEM) as a means of avoiding dehydration in organic solvents, and to provide dimensionally stable biological specimens through a process of air-drying. It has been assumed that shrinkage of specimens prepared by the GACH technique should be less than that of conventionally-prepared material by critical point drying (CPD). In a previous study, Bell has reported significant shrinkage of whole cells for SEM. This report compares cell shrinkage in GACH and CPD preparations.Fibroblasts from newborn rats were grown on collagen-coated glass cover-slips (with alpha numeric grids etched onto the surface of the coverslips) in Eagle's minimum essential medium + 10% fetal calf serum for 7 d. (3). Using an inverted microscope with phase-contrast optics, micrographs were taken of the cultures in their live state and 1 h. after fixation with 2.5% glutaraldehyde in Dulbecco's phosphate buffered saline (Figs. 1 and 3).

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