Abstract:
:A new flow configuration allows a flow cytometer of high resolution and stability to be assembled from an inverted fluorescence microscope with incident illumination, a pulse photometer, and a multichannel pulse height analyzer. A nozzle produces a hydrodynamically focused sample stream in a liquid jet that id directed onto a microscope cover glass in front of the microscope objective. The microscope provides a mechanically stable optical system of high numerical aperture (N.A.) (oil immersion, N.A. = 1.3) for focusing the excitation light and collection of the fluorescence light. The instrument has wide optima with regard to the various characteristics of the flow configuration, such as the rate of sample analysis and sheath flow, and the angle of incidence of the liquid jet, thus making it easy to adjust for optimal performance. DNA histograms of rat thymocytes stained with ethidium bromide and mithramycin demonstrate that all angles of incidence can be used. Large-angle incidence (70 degrees) gives the best resolution, i.e., a coefficient of variance (CV) of 0.9% of the peak of the histogram. This is only slightly better than values obtained at other angles, e.g., CV = 1.3% at vertical (0 degrees) incidence. It is concluded that instrumental resolution is equal to or better than CV = 0.9%. Linearity (proportionality between channel number and fluorescence intensity) is within 1%, and instrumental drift over a 1-h period is normally less than 1-2%.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Lindmo T,Steen HBdoi
10.1016/S0006-3495(79)85157-7subject
Has Abstractpub_date
1979-10-01 00:00:00pages
33-44issue
1eissn
0006-3495issn
1542-0086pii
S0006-3495(79)85157-7journal_volume
28pub_type
杂志文章abstract::Microsecond rotational motions of nitroxide spin labels are measured primarily with saturation transfer electron paramagnetic resonance (ST-EPR). In the present study we have used model system experiments to quantitatively evaluate different ST-EPR spectral parameters, both in-phase and out-of-phase, with an emphasis ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(86)83720-1
更新日期:1986-04-01 00:00:00
abstract::We study the lateral headgroup interactions among phosphatidylcholine (PC) molecules and among phosphatidylethanolamine (PE) molecules in monolayers and extend our previous models. In this paper, we present an extensive set of pressure-area isotherms and surface potential experiments on monolayers of phospholipids ran...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(92)81964-1
更新日期:1992-06-01 00:00:00
abstract::Stepwise two-photon excitation of chlorophyll a and b in the higher plant main light-harvesting complex (LHC II) and the minor complex CP29 (as well as in organic solution) with 100-fs pulses in the Q(y) region results in a weak blue fluorescence. The dependence of the spectral shape of the blue fluorescence on excita...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(02)75509-4
更新日期:2002-03-01 00:00:00
abstract::A detailed model for the kinetics and energetics of the exciton trapping, charge separation, charge recombination, and charge stabilization processes in photosystem (PS) II is presented. The rate constants describing these processes in open and closed reaction centers (RC) are calculated on the basis of picosecond dat...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(88)82973-4
更新日期:1988-09-01 00:00:00
abstract::Hydrophobic interactions between a bilayer and its embedded membrane proteins couple protein conformational changes to changes in the packing of the surrounding lipids. The energetic cost of a protein conformational change therefore includes a contribution from the associated bilayer deformation energy (DeltaGdef0), w...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(99)77252-8
更新日期:1999-02-01 00:00:00
abstract::Trains of nerve impulses from the crayfish stretch receptor under steady conditions are found to be extremely regular with a standard deviation of S = 0.7 x 10(-2)tau when tau, the mean interval, is in the 15 to 80 msec range. Such a small fluctuation increases the problems of film recording, accurate measurement of i...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(66)86651-1
更新日期:1966-03-01 00:00:00
abstract::A mesoscale model of DNA is presented (3SPN.1), extending the scheme previously developed by our group. Each nucleotide is mapped onto three interaction sites. Solvent is accounted for implicitly through a medium-effective dielectric constant and electrostatic interactions are treated at the level of Debye-Hückel theo...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2008.09.061
更新日期:2009-03-04 00:00:00
abstract::The single photon response in vertebrate phototransduction is highly reproducible despite a number of random components of the activation cascade, including the random activation site, the random walk of an activated receptor, and its quenching in a random number of steps. Here we use a previously generated and tested...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.107.114058
更新日期:2008-05-01 00:00:00
abstract::Cysteine residues introduced by site-directed mutagenesis have been used to probe the conformation and dynamics of two receptors in the E. coli chemotaxis pathway. (a) Thermal motions of the polypeptide backbone were investigated in the periplasmic D-galactose and D-glucose receptor, a globular protein of known struct...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(92)81806-4
更新日期:1992-04-01 00:00:00
abstract::Sickle hemoglobin forms long, multistranded polymers that account for the pathophysiology of the disease. The molecules in these polymers make significant contacts along the polymer axis (i.e., axial contacts) as well as making diagonally directed contacts (i.e., lateral contacts). The axial contacts do not engage the...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.09.032
更新日期:2013-11-05 00:00:00
abstract::DNA represents a promising therapeutic and prophylactic macromolecule in treating genetic diseases, infectious diseases and cancers. The therapeutic potential of DNA is directly related to how DNA transports within the targeted tissue. In this study, fluorescence photobleaching recovery was used to examine the diffusi...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.077404
更新日期:2006-07-15 00:00:00
abstract::Synchronous neurotransmitter release is mediated by the opening of voltage-gated Ca(2+) channels and the build-up of submembrane Ca(2+) microdomains. Previous models of Ca(2+) microdomains have neglected possible electrostatic interactions between Ca(2+) ions and negative surface charges on the inner leaflet of the pl...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.107.124909
更新日期:2008-09-01 00:00:00
abstract::Changes in voltage-dependent gating represent a common pathogenetic mechanism for genetically inherited channelopathies, such as benign familial neonatal seizures or peripheral nerve hyperexcitability caused by mutations in neuronal K(v)7.2 channels. Mutation-induced changes in channel voltage dependence are most ofte...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2012.02.004
更新日期:2012-03-21 00:00:00
abstract::ATP-sensitive K(+)-channels link metabolism and excitability in neurons, myocytes, and pancreatic islets. Mutations in the pore-forming subunit (Kir6.2; KCNJ11) cause neonatal diabetes, developmental delay, and epilepsy by decreasing sensitivity to ATP inhibition and suppressing electrical activity. Mutations of resid...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.108.138685
更新日期:2008-11-15 00:00:00
abstract::In its most restrictive interpretation, the notion of chromatin remodeling refers to the action of chromatin-remodeling enzymes on nucleosomes with the aim of displacing and removing them from the chromatin fiber (the effective polymer formed by a DNA molecule and proteins). This local modification of the fiber struct...
journal_title:Biophysical journal
pub_type: 杂志文章,评审
doi:10.1016/j.bpj.2017.12.008
更新日期:2018-05-22 00:00:00
abstract::Nef is an HIV-1 accessory protein that directly contributes to AIDS progression. Nef is myristoylated on the N-terminus, associates with membranes, and may undergo a transition from a solution conformation to a membrane-associated conformation. It has been hypothesized that conformational rearrangement enables membran...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.07.016
更新日期:2010-09-22 00:00:00
abstract::Catch force in molluscan smooth muscle requires little, if any, energy input and is controlled by the phosphorylation state of the thick filament-associated mini-titin, twitchin. The kinetic parameters of myosin cross-bridge turnover in permeabilized catch muscle, and how they are potentially modified by the catch mec...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.107.105577
更新日期:2007-07-15 00:00:00
abstract::The composition and electrolyte concentration of the aqueous bathing environment have important consequences for many biological processes and can profoundly affect the behavior of biomolecules. Nevertheless, because of computational limitations, many molecular simulations of biophysical systems can be performed only ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2018.02.042
更新日期:2018-05-22 00:00:00
abstract::Hypothetical hydroxide and proton migration along the linear water chain in Aquaporin GlpF from Escherichia coli are studied by ab initio Car-Parrinello molecular dynamics simulations. It is found that the protein stabilizes a bipolar single file of water. The single file features a contiguous set of water-water hydro...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.058206
更新日期:2005-09-01 00:00:00
abstract::We have used chemical synthesis, electron paramagnetic resonance (EPR), and circular dichroism to detect and analyze the structural dynamics of a ryanodine receptor (RyR) peptide bound to calmodulin (CaM). The skeletal muscle calcium release channel RyR1 is activated by Ca2+-free CaM and inhibited by Ca2+-bound CaM. T...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2016.10.025
更新日期:2016-12-06 00:00:00
abstract::The coupling between the depolymerization of microtubules (MTs) and the motion of the Dam1 ring complex is now thought to play an important role in the generation of forces during mitosis. Our current understanding of this motion is based on a number of detailed computational models. Although these models realize poss...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.01.004
更新日期:2010-04-21 00:00:00
abstract::Kv1 potassium channels are widely distributed in mammalian tissues and are involved in a variety of functions from controlling the firing rate of neurons to maturation of T-lymphocytes. Here we show that the newly described KCNE4 beta-subunit has a drastic inhibitory effect on currents generated by Kv1.1 and Kv1.3 pot...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)74585-8
更新日期:2003-09-01 00:00:00
abstract::This paper describes a molecular dynamics and molecular mechanics study of the solvation and selectivity of the narrow pore and vestibule region of a model-built structure for the voltage-gated sodium channel. The particular structure used was one proposed by Guy and Durell. However, many of the features we saw would ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(96)79438-9
更新日期:1996-11-01 00:00:00
abstract::Model compound studies in the literature show how Hofmeister ion interactions affect protein stability. Although model compound results are typically obtained as salting-out constants, they can be used to find out how the interactions affect protein stability. The null point in the Hofmeister series, which divides pro...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(96)79404-3
更新日期:1996-10-01 00:00:00
abstract::To understand better the effect of electrostatics on the rigidity of the DNA double helix, we define DNA*, the null isomer of DNA, as the hypothetical structure that would result from DNA if its phosphate groups were not ionized. For the purposes of theoretical analysis, we model DNA* as identical to ordinary DNA but ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.089029
更新日期:2006-11-15 00:00:00
abstract::In this new method for studying the shape recovery of deformed red blood cells, three optical traps ("optical tweezers") induce a parachute-shaped red cell deformation, which is comparable to the deformation in small capillaries. The shape recovery is recorded, and a relaxation time is obtained for each individual red...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(95)80084-6
更新日期:1995-11-01 00:00:00
abstract::Spectroscopic responses of the potentiometric probe 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) were investigated in living cells by means of a time- and space-correlated single photon counting technique. Spatially resolved fluorescence decays from single mitochondria or only a very few organelles o...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.108.135079
更新日期:2008-10-01 00:00:00
abstract::Density-gradient centrifugation of disintegrated cells from a variety of plants gave two kinds of chlorophyll particles from all except the blue-green algae. As in previous procedures using detergents, the lighter Fraction 1 particles usually had greater absorption at longer wavelengths; they always had a lower ratio ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(69)86469-6
更新日期:1969-12-01 00:00:00
abstract::Slow stretch ramps (velocity: 0.17 fiber lengths s-1) were imposed during fused tetanic contractions of intact muscle fibers of the frog (1.4-3.0 degrees C; sarcomere length: 2.12-2.21 microns). Instantaneous force-extension relations were derived both under isometric conditions and during slow stretch by applying fas...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(89)82689-X
更新日期:1989-08-01 00:00:00
abstract::The optical scattering coefficient of a dilute, well-solubilized eumelanin solution has been accurately measured as a function of incident wavelength, and found to contribute <6% of the total optical attenuation between 210 and 325 nm. At longer wavelengths (325-800 nm), the scattering was less than the minimum sensit...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.075713
更新日期:2006-06-01 00:00:00