Absence of biologically related Raman lines in cultures of Bacillus megaterium

Furia, L.; Gandhi, O.P.

doi:10.1016/0375-9601(84)90304-9

Cited by 16 publications

(4 citation statements)

References 10 publications

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“…Several other experiments led by Webb yielded similar results Webb 1980). Furia and Gandhi (1984) attempted to reproduce the experiment of using B. megaterium, but found no Raman lines of biological origin. Cooper and Amer (1983) suggested that the time variations in the spectra observed by were due to clumping of the synchronous cells which produced changes in the total light scattered (Mie scattering from clumped cells) and were not due to specific frequency components.…”

Section: Raman and Brillouin Effectssupporting

confidence: 60%

Quantitative Evaluations of Mechanisms of Radiofrequency Interactions With Biological Molecules and Processes

Sheppard¹,

Swicord²,

Balzano

2008

Health Physics

112

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The complexity of interactions of electromagnetic fields up to 10(12) Hz with the ions, atoms, and molecules of biological systems has given rise to a large number of established and proposed biophysical mechanisms applicable over a wide range of time and distance scales, field amplitudes, frequencies, and waveforms. This review focuses on the physical principles that guide quantitative assessment of mechanisms applicable for exposures at or below the level of endogenous electric fields associated with development, wound healing, and excitation of muscles and the nervous system (generally, 1 to 10(2) V m(-1)), with emphasis on conditions where temperature increases are insignificant (<<1 K). Experiment and theory demonstrate possible demodulation at membrane barriers for frequencies < or =10 MHz, but not at higher frequencies. Although signal levels somewhat below system noise can be detected, signal-to-noise ratios substantially less than 0.1 cannot be overcome by cooperativity, signal averaging, coherent detection, or by nonlinear dynamical systems. Sensory systems and possible effects on biological magnetite suggest paradigms for extreme sensitivity at lower frequencies, but there are no known radiofrequency (RF) analogues. At the molecular level, vibrational modes are so overdamped by water molecules that excitation of molecular modes below the far infrared cannot occur. Two RF mechanisms plausibly may affect biological matter under common exposure conditions. For frequencies below approximately 150 MHz, shifts in the rate of chemical reactions can be mediated by radical pairs and, at all frequencies, dielectric and resistive heating can raise temperature and increase the entropy of the affected biological system.

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Section: Raman and Brillouin Effectssupporting

confidence: 60%

Quantitative Evaluations of Mechanisms of Radiofrequency Interactions With Biological Molecules and Processes

Sheppard¹,

Swicord²,

Balzano

2008

Health Physics

112

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“…[36][37][38][39][40][41][42][43][44][45][46][47] Early attempts to produce nonresonant Raman spectra of bacteria with visible light excitation were unsuccessful due to fluorescence interference. [48][49][50][51][52] More recently excitation in the 200-257 nm range has produced UV resonance Raman spectra for a variety of bacteria and spores. [53][54][55][56][57][58] The routine use of deep UV excitation of aromatic amino acid and nucleic acid species to obtain native fluorescence and resonance Raman signatures in situ has been dependent on the development of a lightweight laser light source emitting photons in the 200-250 nm range.…”

Section: Introductionmentioning

confidence: 99%

Hollow cathode ion lasers for deep ultraviolet Raman spectroscopy and fluorescence imaging

Storrie-Lombardi

Hug

McDonald

et al. 2001

Review of Scientific Instruments

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This article describes the development of hollow cathode ion lasers and their use in constructing an ultraviolet micro-Raman spectrograph with native fluorescence imaging capability. Excitation at 224.3 nm is provided by a helium-silver hollow cathode metal ion laser and at 248.6 nm by a neon-copper hollow cathode metal ion laser. Refractive microscope objectives focus chopped continuous wave laser light on a sample and collect 180°scattered photons. Imaging is accomplished by broadband visible illumination and by deep ultraviolet laser induced excitation of visible wavelength native fluorescence in untagged microorganisms. This makes possible a detection strategy employing rapid imaging with laser excitation to locate regions of native fluorescence activity, followed by deep ultraviolet resonance Raman spectroscopy of the identified fluorescent sites. We have employed this probe for in situ detection of microorganisms on mineral and soil substrates. We present here the deep ultraviolet resonance Raman spectra for the gram negative iron reducing bacterium Shewanella oneidensis obtained while the microorganism remains in situ on the unpolished surface of the mineral calcite and in a Mars soil analog, JSC1. In the current configuration the in situ mineral surface limit of detection for fluorescence is one organism in 2ϫ10 4 m 2 field of view and of order 20-30 microorganisms for Raman spectra. For the Mars soil sample analog fluorescent target selection gives an effective ultraviolet resonance Raman spectral detection limit of 6ϫ10 4 cells/gm or ϳ60 ppb.

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“…Thus it appeared that Davydov's and Frohlich's ideas had found experimental support. However, reports appeared from Cooper and Amer [19], Furia and Gandhi [20], and Kinoshita et al [21] which failed to corroborate Webb's findings. On the other hand reports from For Raman spectra taken with scanning monochromators, both variations in the flow (or motion) of bacteria as they are presented to the laser beam and variations in bacterial fluorescence with time may cause the baseline of the spectrum to vary.…”

Section: Introductionmentioning

confidence: 94%