Kinetics of populating and depopulating of the components of the photoinduced triplet state of the photosynthetic bacteria Rhodospirillum rubrum, rhodopseudomonas spheroides (wild type), and its mutant R-26 as measured by ESR in zero-field

1976 ◽  
Vol 440 (3) ◽  
pp. 765-771 ◽  
Author(s):  
A.J. Hoff
Keyword(s):  
Triplet State ◽  
Photosynthetic Bacteria ◽  
Rhodospirillum Rubrum ◽  
Zero Field ◽  
Wild Type ◽  
Rhodopseudomonas Spheroides ◽  
Kinetics Of

scholarly journals Vitamin B12 in photosynthetic bacteria and methionine synthesis by Rhodopseudomonas spheroides

1967 ◽  
Vol 102 (3) ◽  
pp. 774-781 ◽  
Author(s):  
S. E. Cauthen ◽  
J. R. Pattison ◽  
J Lascelles
Keyword(s):  
Photosynthetic Bacteria ◽  
Methylenetetrahydrofolate Reductase ◽  
Reductase Activity ◽  
Vitamin B ◽  
Wild Type ◽  
E Coli ◽  
Vitamin B 12 ◽  
Rhodopseudomonas Spheroides ◽  
Methionine Synthesis ◽  
Dependent Pathway

1. Assay of some photosynthetic bacteria for vitamin B(12) showed them to be relatively rich in this factor. Rhodopseudomonas spheroides, grown photosynthetically in Co(2+)-supplemented medium, contained about 100mug./g. dry wt. 2. Extracts of wild-type Rps. spheroides methylated homocysteine by a mechanism similar to the cobalamin-dependent pathway present in Escherichia coli. However, no mechanism similar to the cobalamin-independent N(5)-methyltetrahydrofolate-homocysteine transmethylase of E. coli could be detected in Rps. spheroides. 3. N(5)N(10)-Methylenetetrahydrofolate-reductase activity was found in Rps. spheroides. 4. A methionine-requiring mutant strain of Rps. spheroides (strain 2/33), which does not respond to homocysteine, made the same amount of vitamin B(12) as the parent organism. Extracts did not form methionine from N(5)-methyltetrahydrofolate and homocysteine even in the presence of cofactors shown to be necessary with the parent strain, and it is concluded that the mutant is blocked in the formation of the apoenzyme of a homocysteine-methylating system similar to the vitamin B(12)-dependent one in E. coli.

THE USE OF SPECTROPHOTOMETRY IN AN ECOLOGICAL INVESTIGATION OF THE FACULTATIVELY ANAEROBIC PURPLE PHOTOSYNTHETIC BACTERIA

1967 ◽  
Vol 13 (9) ◽  
pp. 1283-1293 ◽  
Author(s):  
Edward F. Haskins ◽  
Toru Kihara
Keyword(s):  
Photosynthetic Bacteria ◽  
Rhodospirillum Rubrum ◽  
Rhodopseudomonas Palustris ◽  
Rhodopseudomonas Capsulata ◽  
Purple Photosynthetic Bacteria ◽  
Ecological Investigation ◽  
Facultatively Anaerobic ◽  
Isolation Techniques ◽  
Spectral Evidence ◽  
Rhodopseudomonas Spheroides

Diverse habitats were surveyed for the presence of Athiorhodaceae, using isolation techniques that permitted the development of only the facultatively anaerobic species of this family: Rhodopseudomonas capsulata, Rhodopseudomonas gelatinosa, Rhodopseudomonas palustris, Rhodopseudomonas spheroides, and Rhodospirillum rubrum. Of the 150 samples of soil, mud, sand, and water inoculated into enrichment media, 125 initiated cultures of photosynthetic bacteria, as indicated by spectrophotometric examination of the cultures. Subsequently, eight of these cultures were intensively investigated and isolates of the four species of Rhodopseudomonas were identified. Attempts to isolate Rhodospirillum rubrum from the cultures were unsuccessful. Species identifications were based on spectral examinations of aqueous cell-free preparations of the photosynthetic bacterial pigments. The species determinations based on the spectral evidence agreed with those based on the morphological and physiological criteria currently used for the identification of the Athiorhodaceae.

scholarly journals Kinetics of Neutralizing Antibodies of COVID-19 Patients Tested Using Clinical D614G, B.1.1.7 and B 1.351 Isolates in Microneutralization Assays

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 996
Author(s):  
Jenni Virtanen ◽  
Ruut Uusitalo ◽  
Essi M. Korhonen ◽  
Kirsi Aaltonen ◽  
Teemu Smura ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Acute Infection ◽  
Clinical Isolates ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Kinetics Of

Increasing evidence suggests that some newly emerged SARS-CoV-2 variants of concern (VoCs) resist neutralization by antibodies elicited by the early-pandemic wild-type virus. We applied neutralization tests to paired recoveree sera (n = 38) using clinical isolates representing the first wave (D614G), VoC1, and VoC2 lineages (B.1.1.7 and B 1.351). Neutralizing antibodies inhibited contemporary and VoC1 lineages, whereas inhibition of VoC2 was reduced 8-fold, with 50% of sera failing to show neutralization. These results provide evidence for the increased potential of VoC2 to reinfect previously SARS-CoV-infected individuals. The kinetics of NAbs in different patients showed similar decline against all variants, with generally low initial anti-B.1.351 responses becoming undetectable, but with anti-B.1.1.7 NAbs remaining detectable (>20) for months after acute infection.

scholarly journals A network of Rab GTPases controls phagosome maturation and is modulated by Salmonella enterica serovar Typhimurium

2007 ◽  
Vol 176 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Adam C. Smith ◽  
Won Do Heo ◽  
Virginie Braun ◽  
Xiuju Jiang ◽  
Chloe Macrae ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Dominant Negative ◽  
Rab Gtpases ◽  
Wild Type ◽  
Intracellular Growth ◽  
Non Invasive ◽  
Serovar Typhimurium ◽  
Guanosine Triphosphatase ◽  
Kinetics Of

Members of the Rab guanosine triphosphatase (GTPase) family are key regulators of membrane traffic. Here we examined the association of 48 Rabs with model phagosomes containing a non-invasive mutant of Salmonella enterica serovar Typhimurium (S. Typhimurium). This mutant traffics to lysosomes and allowed us to determine which Rabs localize to a maturing phagosome. In total, 18 Rabs associated with maturing phagosomes, each with its own kinetics of association. Dominant-negative mutants of Rab23 and 35 inhibited phagosome–lysosome fusion. A large number of Rab GTPases localized to wild-type Salmonella-containing vacuoles (SCVs), which do not fuse with lysosomes. However, some Rabs (8B, 13, 23, 32, and 35) were excluded from wild-type SCVs whereas others (5A, 5B, 5C, 7A, 11A, and 11B) were enriched on this compartment. Our studies demonstrate that a complex network of Rab GTPases controls endocytic progression to lysosomes and that this is modulated by S. Typhimurium to allow its intracellular growth.

scholarly journals Bactericidal Activity, Absence of Serum Effect, and Time-Kill Kinetics of Ceftazidime-Avibactam against β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

2014 ◽  
Vol 58 (9) ◽  
pp. 5297-5305 ◽  
Author(s):  
Tiffany R. Keepers ◽  
Marcela Gomez ◽  
Chris Celeri ◽  
Wright W. Nichols ◽  
Kevin M. Krause
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Human Serum ◽  
Bactericidal Activity ◽  
Minimum Bactericidal Concentration ◽  
Wild Type ◽  
Content Type ◽  
Positive Isolate ◽  
New Treatment ◽  
Time Kill ◽  
Kinetics Of

ABSTRACTAvibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18Pseudomonas aeruginosaisolates and 15Enterobacteriaceaeisolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2P. aeruginosaisolates (1blaVIM-positive isolate and 1blaOXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log10decrease in the number of CFU/ml was observed at 6 h for allEnterobacteriaceae, and a 2-log10reduction in the number of CFU/ml was observed at 6 h for 3 of the 6P. aeruginosaisolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused byEnterobacteriaceaeandP. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.

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