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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Comparison of bioseparation methods for microgravity experiments

The efficiency of the 1-g version of the continuous-flow electrophoresis (CFE) system flown on Space Shuttle missions is compared with the efficiency of a commercial CFE for separating living cells (human kidney, liver, and pituitary-gland cells and T-lymphocytes). In addition, the CFE system and a reciprocal isoelectric focusing (RIEF) system are compared with respect to protein pyrification efficiency. Correlations were made among electrophoretic mobilities (EPMs), secretory functions of cells, and input sample concentrations. A significant reduction in mean and range EPM was observed when input sample concentrations exceeded a low threshohold. This effect was not observed in microgravity experiments conducted at sample concentrations three times greater than the threshold for the controls. Comparison of CFE and RIEF methods showed that there are apparent advantages for each method depending on the product. For example, RIEF purification of urokinase removed more protein impurities, but focused the enzyme at a pH different than the enzyme's known isoelectric point.

Morrison, Dennis R.↗
NASA NTRS2000

Fluorescence Studies of Protein Crystal Nucleation

We have postulated that, in the case of tetragonal chicken egg white lysozyme, crystal growth occurs by the addition of pre-critical nuclei sized n-mers that form in the bulk solution, and that the n-mer growth units were multiples of the tetrameric 4(sub 3) helical structure. These have the strongest intermolecular bonds in the crystal and are therefore likely to be the first species formed. High resolution AFM studies provide strong supporting evidence for this model, but the data also suggest that the actual species in solution may not be identical in structure to that found in the crystal. We are using fluorescence resonance energy transfer (FRET) to study the initial solution phase self-assembly process, using covalent fluorescent derivatives which crystallize in the characteristic P4(sub 3)2(sub 1)2(sub 1) space group. FRET studies are being carried out between the cascade blue (CB-lys, donor, Ex(sub max) 366 nm, Em 420 nm) and lucifer yellow (LY-lys, acceptor, Ex(sub max) 430 nm, Em 528 nm) asp101 derivatives. The estimated R(sub 0) for this probe pair, the distance where 50% of the donor energy is transferred to the acceptor, is approx. 1.2 nm, compared to 2.2 nm between the side chain carboxyls of adjacent asp101's in the crystalline 4(sub 3) helix. The short donor lifetime of 2.80 ns (chi(sup 2) = 0.644), coupled with the large average distances between the molecules (greater than or equal to 50 nm) in solution, ensure that any energy transfer observed is not due to random diffusive interactions. Lifetime data show that CB-lys has a single lifetime when it is the only species in solution. Similarly, LY-lys also exhibits a single lifetime of 4.63 ns (chi(sup 2) = 0.42) when alone in solution. Addition of LY-lys to CB-lys results in the appearance of a third lifetime component of 0.348ns for the CB-lys. The fractional intensities of the different species present can be used to estimate the distribution of monomer and n-mers in solution. The self-association process is a function of the protein concentration relative to the saturation concentration, and observing it in dilute solution (conc. less than or equal to 10(exp -5)M) requires that the experiments be performed under low solubility conditions, i.e., low temperatures and high salt concentrations. Data from preliminary steady state FRET studies with N-terminal bound pyrene acetic acid (PAA-lys, donor, Ex 340 nm, Em 376 nm) and asp101 LY-lys as an acceptor showed a consistent trend of decreasing donor fluorescence intensity with increasing total protein concentration. The FRET data have been obtained at pH 4.6, 0.1M NaAc buffer, at 5 and 7% NaCl, 4 C. The corresponding C(sub sat) values are 0.471 and 0.362 mg/ml (approx. 3.3 and approx. 2.5 x 10(exp -5)M respectively). The donor fluorescence decrease is more pronounced at7% NaCl, consistent with the expected increased intermolecular interactions at higher salt concentrations as reflected in the lower solubility. Results from these and other ongoing studies will be discussed in conjunction with an emerging model for how tetragonal lysozyme crystals nucleate and the relevance of that model to other proteins.

Pusey, Marc↗
NASA NTRS2014

Failure Investigation of WB-57 Aircraft Engine Cowling

The NASA Johnson Space Center (JSC) in Houston, Texas is the home of the NASA WB-57 High Altitude Research Program. Three fully operational WB-57 aircraft are based near JSC at Ellington Field. The aircraft have been flying research missions since the early 1960's, and continue to be an asset to the scientific community with professional, reliable, customer-oriented service designed to meet all scientific objectives. The NASA WB-57 Program provides unique, high-altitude airborne platforms to US Government agencies, academic institutions, and commercial customers in order to support scientific research and advanced technology development and testing at locations around the world. Mission examples include atmospheric and earth science, ground mapping, cosmic dust collection, rocket launch support, and test bed operations for future airborne or spaceborne systems. During the return from a 6 hour flight, at 30,000 feet, in the clean configuration, traveling at 175 knots indicated airspeed, in un-accelerated flight with the auto pilot engaged, in calm air, the 2-man crew heard a mechanical bang and felt a slight shudder followed by a few seconds of high frequency vibration. The crew did not notice any other abnormalities leading up to, or for the remaining 1 hour of flight and made an uneventful landing. Upon taxi into the chocks, the recovery ground crew noticed the high frequency long wire antenna had become disconnected from the vertical stabilizer and was trailing over the left inboard wing, and that the left engine upper center removable cowling panel was missing, with noticeable damage to the left engine inboard cowling fixed structure. The missing cowling panel was never recovered. Each engine cowling panel is attached to the engine nacelle using six bushings made of 17-4 PH steel. The cylinder portions of four of the six bushings were found still attached to the aircraft (Fig 1). The other two bushings were lost with the panel. The other four bushings exhibited ratchet marks (multiple fatigue origins) which initiated in the sharp radius of the flange/cylinder fillet and were observed 300 degrees around the flange perimeter (Fig 2-3). Low stress, high cycle fatigue (HCF) was observed on the fracture surfaces of all four bushings (Fig 4). To improve the cowling panel joint design and enable return to flight, new cowling bushings with thicker flanges and a larger machined flange/cylinder fillet radius were installed on all cowling panels. In addition, a spacer was added to the joint to achieve the proper stack tolerance. Finally, a time change requirement for all cowling bushings was instituted.

Martinez, J. E.↗
NASA NTRSDate not supplied

Remodeling BioSentinel’s Microbial Metabolism Measurement System

BioSentinel, the first biological CubeSat beyond low Earth orbit, will investigate how Saccharomyces cerevisiae responds to ionizing radiation using optical measurements of a colorimetric metabolic indicator dye (alamarBlue). To map optical data to more detailed metabolic measurements, a microbial culture system for ground testing was designed consisting of a 400 mL beaker and a rubber stopper with pass-through holes for its five sensor probes (electrical conductivity, pH, oxidation-reduction potential, dissolved oxygen, optical density). The initial design had several drawbacks. It was only partially reusable due to its one-time sealants: Teflon tape and parafilm. A steady increase in oxygen levels within the sensor’s testingdata indicated the design was not sufficiently airtight. Degradation of the rubber stopper’s elasticity due to sterilization and reinsertion of the probes led to poor robustness and eventual replacement. The vessel’s large headspace didn’t reproduce flight conditions and a large culture volume required more reagents. The system has been redesigned to contain a rigid, biocompatible polycarbonate disc lid that allows for threaded inserts. The culture vessel’s height will be reduced from 110 mm to 65 mm to decrease overhead space and material costs. A more reliable seal will be achieved with a gasket and clamps. The optical probe records absorbance at four wavelengths to characterize cell density and alamarBlue dye ratios. A pneumatically operated plunger draws media through the hollow interior of the probe. Currently, deformation of the silicone on the plunger causes asymmetrical movement and a drift from its initial state. Designs are being developed to limit the plunger’s travel for a more accurate measurement cycle. The remodeled system is under construction and will be tested for leaks and accuracy. The measurements collected will be used to provide additional insight into the optical data returned from the BioSentinel mission.

Astrobiology↗
NASA NTRS1986

Computer simulation of immobilized pH gradients at acidic and alkaline extremes - A quest for extended pH intervals

Computer simulations of the concentration profiles of simple biprotic ampholytes with Delta pKs 1, 2, and 3, on immobilized pH gradients (IPG) at extreme pH values (pH 3-4 and pH 10-11) show markedly skewed steady-state profiles with increasing kurtosis at higher Delta pK values. Across neutrality, all the peaks are symmetric irrespective of their Delta pK values, but they show very high contribution to the conductivity of the background gel and significant alteration of the local buffering capacity. The problems of skewness, due to the exponential conductivity profiles at low and high pHs, and of gel burning due to a strong electroosmotic flow generated by the net charges in the gel matrix, also at low and high pHs, are solved by incorporating in the IPG gel a strong viscosity gradient. This is generated by a gradient of linear polyacrylamide which is trapped in the gel by the polymerization process.

Mosher, Richard A.↗
NASA NTRS1991

The effect of low-temperature hydrothermal alteration on the remanent magnetization of synthetic titanomagnetites - A case for acquisition of chemical remanent magnetization

Experiments were performed demonstrating that a chemical remanent magnetization (CRM) can be acquired during the aqueous oxidation of synthetic titanomagnetites (TM40:Fe/2.6/Ti/0.4/O4) by the removal of iron, as it does in the oceanic crust basalts. Results showed that the CRM is acquired along the ambient field direction during oxidation, and that there is no coupling of the CRM and the thermoremanent magnetization. The rate of oxidation was found to be pH-dependent, with the amount of CRM acquired varying inversely with the pH of the oxidizing solution. The reaction produced nascent hydrogen gas. Results support the chemical equation for titanomagnetic oxidation proposed by Worm and Banerjee (1984).

Kelso, Paul R.↗
NASA NTRS2002

The BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 1984), as well as new transient sources discovered with BATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling to about 175 objects. The catalog will present the global properties of these sources and their probability of detection (greater than 10 mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the High Energy Astrophysics Science Archive Research Center (HEASARC) for public use.

Harmon, B. A.↗
NASA NTRS1983

IPE 7

A description is given of the collection and treatment of samples of Prochloron cells. The cells of Prochloron were obtained and prepared in the following way. Colonies of the symbiotic host, the giant didemnid ascidian Lissoclinum patella, were collected at low-tide level on reef-flat sand between Kamori Island and Koror, Palau, Western Caroline Islands. The animal colonies were taken, immersed in sea water, to an 8,000-litre holding tank and kept with constantly running sea water at 30 deg. Individual colonies were picked clean of contaminants, rinsed in sea water buffered with 40 nM or 100 mM Tris buffer at pH 8.4, and squeezed by hand to express the algal cells from the cloacal atria. The algae were received in about an equal volume of the same buffered sea water; this neutralized the acids liberated by the bruised ascidians and thereby maintained the Ph high enough to keep the algal cells green. The Prochloron cells were washed twice with buffered sea water and concentrated by centrifugation at about 50 g for 90 seconds. Microscopic examination revealed that contamination by animal host cells or bacteria was negligible (much less than 1%).

Source record↗
NASA NTRS2004

The BATSE Earth Occultation Catalog of Low Energy Gamma-Ray Sources

The Burst and Transient Source Experiment (BATSE),aboard the COmptOn Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 19841, as well as new transient sources discovered with RATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling about 175 objects. The catalog will present the global properties of these sources and their probability of detection (>lO mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the HEASARC for public use.

Harmon, B. A.↗
NASA NTRS1971

Automated Microbial Metabolism Laboratory

The effect of several environmental parameters on previously developed life detection systems is explored. Initial attempts were made to conduct all the experiments in a moist mode (high soil volume to water volume ratio). However, only labeled release and measurement of ATP were found to be feasible under conditions of low moisture. Therefore, these two life detection experiments were used for most of the environmental effects studies. Three soils, Mojave (California desert), Wyaconda (Maryland, sandy loam) and Victoria Valley (Antarctic desert) were generally used throughout. The environmental conditions studied included: incubation temperature 3 C to 80 C, ultraviolet irradiation of soils, variations in soil/liquid ratio, specific atmospheric gases, various antimetabolites, specific substrates, and variation in pH. An experiment designed to monitor nitrogen metabolism was also investigated.

Source record↗
NASA NTRS1985

Transient proton inflows during illumination of anaerobic Halobacterium halobium cells

The roles of bacteriorhodopsin (bR), halorhodopsin (hR), and the H(+)-ATPase in the proton uptake in intact cells are examined. The Halobacterium halobium strains and solutions utilized in the experiment, and the techniques for measuring extracellular pH changes and intracellular K(+) concentrations are described. It is observed that in Halobacterium halobium strain R1, containing bR and hR, the light-driven proton uptake is divided into three transient inflows superimposed on the larger proton outflow. Under anaerobic conditions early proton uptake consists of an inflow which can be blocked with Dio-9 and a second inflow that can be eliminated by low concentrations (less than 125 nm) of triphenyltin chloride (TPT). The effects of Dio-9 and TPT on the passive proton-hydroxyl permeability of the cell membrane are investigated. A third transient light-driven proton flow observed at later times of illumination is studied. The data reveal that the first proton inflow correlates with proton dependent ATP synthesis; the second inflow is a passive uptake through an unidentified channel in response to electrogenic chloride pumping by bR and/or hR; and the third inflow correlates with the Na(+)/H(+) antiporter function.

Helgerson, S. L.↗
NASA NTRS2004

Multisensor Instrument for Real-Time Biological Monitoring

The figure schematically depicts an instrumentation system, called a fiber optic-based integration system (FOBIS), that is undergoing development to enable real-time monitoring of fluid cell cultures, bioprocess flows, and the like. The FOBIS design combines a micro flow cytometer (MFC), a microphotometer (MP), and a fluorescence-spectrum- or binding-force-measuring micro-sensor (MS) in a single instrument that is capable of measuring multiple biological parameters simultaneously or sequentially. The fiber-optic-based integration system is so named because the MFC, the MP, and the MS are integrated into a single optical system that is coupled to light sources and photometric equipment via optical fibers. The optical coupling components also include a wavelength-division multiplexer and diffractive optical elements. The FOBIS includes a laserdiode- and fiber-optic-based optical trapping subsystem (optical tweezers ) with microphotometric and micro-sensing capabilities for noninvasive confinement and optical measurement of relevant parameters of a single cell or other particle. Some of the measurement techniques implemented together by the FOBIS have long been used separately to obtain basic understanding of the optical properties of individual cells and other organisms, the optical properties of populations of organisms, and the interrelationships among these properties, physiology of the organisms, and physical processes that govern the media that surround the organisms. For example, flow cytometry yields information on numerical concentrations, cross-sectional areas, and types of cells or other particles. Micro-sensing can be used to measure pH and concentrations of oxygen, carbon dioxide, glucose, metabolites, calcium, and antigens in a cell-culture fluid, thereby providing feedback that can be helpful in improving control over a bioprocess. Microphotometry (including measurements of scattering and fluorescence) can yield further information about optically trapped individual particles. In addition to the multifunctionality not previously available in a single biological monitoring system, the FOBIS offers advantages of low mass, sensitivity, accuracy, portability, low cost, compactness (the overall dimensions of the fully developed FOBIS sensor head are expected to be less than 1 by 1 by 2 cm), and immunity to electromagnetic interference at suboptical frequencies. FOBIS could be useful in a variety of laboratory and field settings in such diverse endeavors as medical, veterinary, and general biological research; medical and veterinary diagnosis monitoring of industrial bioprocesses; and analysis of biological contaminants in air, water, and food.

Zhang, Sean (Zhanxiang)↗
NASA NTRS1982

Layered transition metal thiophosphates /MPX3/ as photoelectrodes in photoelectrochemical cells

Layered crystals of the transition metal thiophosphates were synthesized and characterized for use as photoelectrodes in photoelectrochemical cells. Crystals incorporating tin and manganese show n-type response while those with iron and nickel show p-type response. These materials have a measured indirect bandgap of about 2.1 eV. They show ability to photoelectrolyze water in acid solutions with onset potentials which change in a Nernstian way as the PH of the solution changes. The onset potential is near zero volts versus a saturated calomel electrode at pH 2. At n-type crystals, oxygen could be evolved upon irradiation at underpotentials of 850 mV and at p-type crystals, hydrogen could be evolved at underpotentials of 400 mV, indicating a net gain in energy conversion. All crystals were unstable in basic solution. Liquid junction photovoltaic cells in iodide-triiodide acid solution using these layered materials were also constructed and found to have low efficiences.

Byvik, C. E.↗
NASA NTRS2004

Analysis of Stainless Steel Sandwich Panels with a Metal Foam Core for Lightweight Fan Blade Design

The quest for cheap, low density and high performance materials in the design of aircraft and rotorcraft engine fan and propeller blades poses immense challenges to the materials and structural design engineers. The present study investigates the use of a sandwich foam fan blade mae up of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. The resulting structures possesses a high stiffness while being lighter than a similar solid construction. The material properties of 17-4 PH metal foam are reviewed briefly to describe the characteristics of sandwich structure for a fan blade application. A vibration analysis for natural frequencies and a detailed stress analysis on the 17-4 PH sandwich foam blade design for different combinations of kin thickness and core volume are presented with a comparison to a solid titanium blade.

Min, James B.↗
NASA NTRS1998

Shewanella amazonensis sp. nov., a novel metal-reducing facultative anaerobe from Amazonian shelf muds

A new bacterial species belonging to the genus Shewanella is described on the basis of phenotypic characterization and sequence analysis of its 16S rRNA-encoding and gyrase B (gyrB) genes. This organism, isolated from shallow-water marine sediments derived from the Amazon River delta, is a Gram-negative, motile, polarly flagellated, facultatively anaerobic, rod-shaped eubacterium and has a G&C content of 51.7 mol%. Strain SB2BT is exceptionally active in the anaerobic reduction of iron, manganese and sulfur compounds. SB2BT grows optimally at 35 degrees C, with 1-3% NaCl and over a pH range of 7-8. Analysis of the 16S rDNA sequence revealed a clear affiliation between strain SB2BT and members of the gamma subclass of the class Proteobacteria. High similarity values were found with certain members of the genus Shewanella, especially with Shewanella putrefaciens, and this was supported by cellular fatty acid profiles and phenotypic characterization. DNA-DNA hybridization between strain SB2BT and its phylogenetically closest relatives revealed low similarity values (24.6-42.7%) which indicated species status for strain SB2BT. That SB2BT represents a distinct bacterial species within the genus Shewanella is also supported by gyrB sequence analysis. Considering the source of the isolate, the name Shewanella amazonensis sp. nov. is proposed and strain SB2BT (= ATCC 700329T) is designated as the type strain.

NASA Discipline Exobiology↗
NASA NTRS2000

High relative humidity increases yield, harvest index, flowering, and gynophore growth of hydroponically grown peanut plants

Growth chamber experiments were conducted to study the physiological and growth response of peanut (Arachis hypogaea L.) to 50% and 85% relative humidity (RH). The objective was to determine the effects of RH on pod and seed yield, harvest index, and flowering of peanut grown by the nutrient film technique (NFT). 'Georgia Red' peanut plants (14 days old) were planted into growth channels (0.15 x 0.15 x 1.2 m). Plants were spaced 25 cm apart with 15 cm between channels. A modified half-Hoagland solution with an additional 2 mM Ca was used. Solution pH was maintained between 6.4 and 6.7, and electrical conductivity (EC) ranged between 1100 and 1200 microS cm-1. Temperature regimes of 28/22 degrees C were maintained during the light/dark periods (12 hours each) with photosynthetic photon flux (PPF) at canopy level of 500 micromoles-m-2s-1. Foliage and pod fresh and dry weights, total seed yield, harvest index (HI), and seed maturity were greater at high than at low RH. Plants grown at 85% RH had greater total and individual leaflet area and stomatal conductance, flowered 3 days earlier and had a greater number of flowers reaching anthesis. Gynophores grew more rapidly at 85% than at 50% RH.

NASA Discipline Life Support Systems↗
NASA NTRS1983

Upper Limits to the Annihilation Radiation Luminosity of Centaurus a

A high resolution observation of the active nucleus galaxy Centaurus A (NGC 5128) was made by the GSFC low energy gamma-ray spectrometer (LEGS) during a balloon flight on 1981 November 19. The measured spectrum between 70 and 500 keV is well represented by a power law of the form 1.05 x 10 (-4) (E/100 keV) (-1.59) ph/sq cm /s with no breaks or line features observed. The 98% confidence (2 sigma) flux upper limit for a narrow ( 3 keV) 511-keV positron annihilation line is 9.9 x 10 (-4) ph/ sq cm /s. Using this upper limit, the ratio of the narrow-line annihilation radiation luminosity to the integral or = 511 keV luminosity is estimated to be 0.09 (2 sigma upper limit). This is compared with the measured value for our galactic center in the Fall of 1979 of 0.10 to 0.13, indicating a difference in he emission regions in the nuclei of the two galaxies.

Gehrels, N.↗
NASA NTRS2001

Distribution and Spectroscopy of Green Fluorescent Protein and Acyl-CoA: Cholesterol Acytransferase in Sf21 Insect Cells

Acyl-CoA: cholesterol acyltransferase (ACAT) is thought to significantly participate in the pathway of cholesterol esterification that underlies the pathology of artherosclerosis. This enzyme is a membrane protein known to be preferentially bound within the endoplasmic reticulum of mammalian cells, from which location it esterifies cholesterol derived from low density lipoprotein. Cultures of insect cells were separately infected with baculovirus containing the gene for green fluroescent protein (GFP) and with baculovirus containing tandem genes for GFP and ACAT. These infected cultures expressed GFP and the fusion protein GCAT, respectively, with maximum expression occurring on the fourth day after infection. Extraction of GFP- and of GCAT-expressing cells with urea and detergent resulted in recovery of fluorescent protein in aqueous solution. Fluorescence spectra at neutral pH were identical for both GFP and GCAT extracts in aqueous solution, indicating unperturbed tertiary structure for the GFP moiety within GCAT. In a cholesterol esterification assay, GCAT demonstrated ACAT activity, but with less efficiency compared to native ACAT. It was hypothesized that the membrane protein ACAT would lead to differences in localization of GCAT compared to GFP within the respective expressing insect cells. The GFP marker directly and also within the fusion protein GCAT was accordingly used as the intracellular probe that was fluorescently analyzed by the new biophotonics technique of hyperspectral imaging. In that technique, fluorescence imaging was obtained from two dimensional arrays of cells, and regions of interest from within those images were then retrospectively analyzed for the emission spectra that comprises the image. Results of hyperspectral imaging of insect cells on day 4 postinfection showed that GCAT was preferentially localized to the cytoplasm of these cells compared to GFP. Furthermore, the emission spectra obtained for the localized GCAT displayed a peak blue shift from 518nm obtained in neutral aqueous solution to 505nm obtained in localized regions within the cells. This blue shift indicates change in the fluorescence coupling of the GFP moiety of GCAT. It is hypothesized that change in tertiary environment of GCAT, coincident with intracellular deposition of GCAT, follows from intracellular trafficking of GCAT leading to membrane interactions with the ACAT moiety, and/or self-assembly of GCAT, that alters the chromophore environment of the GFP moiety of GCAT. These findings introduce a new technique of biophotonic imaging to studies of intracellular protein trafficking and interactions. This technique of hyperspectral imaging could contribute to advancing the emergent field of proteomics. Because of the noninvasive nature of this technique, kinetic processes associated with intracellular protein trafficking, and interactions of proteins within cellular domains, can be considered for investigation within a single cell as well as a cell population.

Richmond, R. C.↗