Abstract:
:The nuclei of epididymal sperm, isolated from C57BL/6J and CBA/J inbred mice by their resistance to trypsin digestion, retain the shape differences of the intact sperm head. Various physical characteristics of these nuclei were measured and compared. The measurement of the projected dimensions of nuclei showed that the CBA nuclei are 13.5% longer than C57BL/6 nuclei (8.64 +/- 0.02 mum compared with 7.61 +/- 0.02 mum), 0.8% narrower (3.51 +/- 0.01 vs. 3.54 +/-0.01 mum) with 6.8% more area (22.34 +/- 0.10 vs. 20.91 +/- 0.09 mum2). However, the volumes of the nuclei as based on reconstructing calibrated electronmicrographs of serial sections of the nuclei indicated that CBA are about 7% smaller than C57BL/6 nuclei (3.72 +/- 0.08 vs. 4.01 +/- 0.03 mum3). The buoyant density of the CBA nuclei is 1.435 +/- 0.002 g/cm3 compared with 1.433 +/- 0.002 g/cm3 for the C57BL/6 nuclei as determined on linear CsCl and Renografin-76 density gradients and confirmed by a technique utilizing physiological tonicities. Therefore, the average mass of the CBA nuclei is less than that of the C57BL/6 nuclei (5.34 +/- 0.12 vs. 5.75 +/- 0.05 pg). The sedimentation velocities at unit gravity of nuclei from 11 inbred strains differ over a range of more than 6% with CBA nuclei sedimenting about 2.0% more slowly than C57BL/6 nuclei. We show that for these nuclei the sedimentation velocity can be related to their buoyant density, volume and a sedimentation shape factor. Within the errors of our measurements of these various characteristics, it was found that C57BL/6 and CBA nuclei have similar sedimentation shape factors. Therefore, the difference in sedimentation velocity between these nuclei appears to be primarily a result of differences in volume. The possible applications of these techniques to the physical separation of sperm are evaluated in the discussion.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Wyrobek AJ,Meistrich ML,Furrer R,Bruce WRdoi
10.1016/S0006-3495(76)85730-Xsubject
Has Abstractpub_date
1976-07-01 00:00:00pages
811-25issue
7eissn
0006-3495issn
1542-0086pii
S0006-3495(76)85730-Xjournal_volume
16pub_type
杂志文章abstract::The rotation of the lever arm of myosin cross-bridges is believed to be responsible for muscle contraction. To resolve details of this rotation, it is necessary to observe a single cross-bridge. It is still impossible to do so in muscle fiber, but it is possible to investigate a small population of cross-bridges by si...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.045450
更新日期:2004-12-01 00:00:00
abstract::We have characterized the fluorescence properties of 6-dodecanoyl-2-dimethylamine-naphthalene (LAURDAN) in pure interfaces formed by sphingomyelin and 10 chemically related glycosphingolipids (GSLs).1 The GSLs contain neutral and anionic carbohydrate residues in their oligosaccharide chain. These systems were studied ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(98)77517-4
更新日期:1998-07-01 00:00:00
abstract::Current viral docking models have relied upon the assumption that bond formation and breakage are independent of viral and docking surface geometry, as well as the forces exerted on the bonds. This assumption, known as the equivalent site hypothesis (ESH), is examined in detail using a newly developed simulation techn...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.103.027813
更新日期:2004-06-01 00:00:00
abstract::The effects of Mg++ on the spatial organization of nuclei from rat hepatocytes are analyzed in the range 0-60 mM, in the presence of suitable concentrations of KCl to reproduce physiological conditions. It is shown that the scatter-signal distribution measured by means of a flow microfluorimeter is greatly affected by...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(85)83938-2
更新日期:1985-04-01 00:00:00
abstract::Muscle contraction occurs as the result of actin-myosin interaction, which is mediated by the intermolecular forces exerted at the actin-myosin interface. To obtain information about the nature of these intermolecular forces, we tested the sensitivity of various contractile parameters of skinned skeletal muscle fibers...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(00)76850-0
更新日期:2000-06-01 00:00:00
abstract::Mechanosensitive ion channels (MSCs) which could provide for fast osmoregulatory responses in bacteria, remain unidentified as molecular entities. MSCs from Escherichia coli (strain AW740) were examined using the patch-clamp technique, either (a) in giant spheroplasts, (b) after reconstitution by fusing native membran...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(93)81044-0
更新日期:1993-07-01 00:00:00
abstract::We describe a new method for selective laser killing of bacteria targeted with light-absorbing gold nanoparticles conjugated with specific antibodies. The multifunctional photothermal (PT) microscope/spectrometer provides a real-time assessment of this new therapeutic intervention. In this integrated system, strong la...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.061895
更新日期:2006-01-15 00:00:00
abstract::The polar interface of membranes containing phosphatidylglycerol or cholesterol was studied by (2)H nuclear magnetic resonance (NMR) as a function of membrane hydration. The membranes were macroscopically aligned and hydrated with deuterium oxide. Water uptake and membrane annealing was achieved under NMR control, usi...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(00)76788-9
更新日期:2000-05-01 00:00:00
abstract::Previous studies on aurein 2.2 and 2.3 in DMPC/DMPG and POPC/POPG membranes have shown that bilayer thickness and phosphatidylglycerol content have a significant impact on the interaction of these peptides with membrane bilayers. Further examination with the DiSC(3)5 assay has indicated that aurein 2.2 induces greater...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.08.077
更新日期:2010-11-03 00:00:00
abstract::We describe a model that relates the maximum shortening velocity of a muscle fiber, Vm, to the kinetics of the dissociation of a myosin head from actin. At Vm, the positive work exerted by cross-bridges attached in the powerstroke must be balanced by cross-bridges that have been carried by movement of the filaments in...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(94)80854-9
更新日期:1994-03-01 00:00:00
abstract::Singlet-triplet mixing in the initial radical-pair state, P[unk]I[unk], of photosynthetic bacterial reaction centers is due to the hyperfine mechanism at low magnetic fields and both the hyperfine and Deltag mechanisms at high magnetic fields (>1 kG). Since the hyperfine field felt by the electron spins in P[unk]I[unk...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(87)83421-5
更新日期:1987-06-01 00:00:00
abstract::Molecular dynamics simulations have been performed of the sequence-symmetric cyclic decapeptide antibiotic gramicidin S (GS), in interaction with a hydrated dimyristoylphosphatidylcholine (DMPC) bilayer, and the results compared with a "control" simulation of the system in the absence of GS. Following experimental evi...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(00)76424-1
更新日期:2000-10-01 00:00:00
abstract::Freeze-fracture electron micrographs from degranulating cells show that the lumen of the secretory granule is connected to the extracellular compartment via large (20 to 150 nm diameter) aqueous pores. These exocytotic fusion pores appear to be made up of a highly curved bilayer that spans the plasma and granule membr...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(92)81679-X
更新日期:1992-10-01 00:00:00
abstract::The supertwisted, double-stranded, replicative intermediate of øX174 DNA (RFI) has been used to determine whether one of the two strands of the double helix is uniquely sensitive to induction of single-strand breaks by ionizing radiation. This could result from a particularly sensitive base sequence or a transfer of e...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(73)85970-3
更新日期:1973-01-01 00:00:00
abstract::The crowded environment of cells poses a challenge for rapid protein-protein association. Yet, it has been established that the rates of association are similar in crowded and in dilute solutions. Here we probe the pathway leading to fast association between TEM1 β-lactamase and its inhibitor protein BLIP in crowded s...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2012.08.009
更新日期:2012-09-05 00:00:00
abstract::Conditions for which a ligand reversibly bound to a cell surface dissociates and then rebinds to the surface have been theoretically examined. The coupled differential equations that describe reaction at the interface between sites on a plane and three-dimensional solution have been described previously (Thompson, N. ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(98)77836-1
更新日期:1998-03-01 00:00:00
abstract::In recent experimental reports, robust circadian oscillation of the phosphorylation level of KaiC has been reconstituted by incubating three cyanobacterial proteins, KaiA, KaiB, and KaiC, with ATP in vitro. This reconstitution indicates that protein-protein interactions and the associated ATP hydrolysis suffice to gen...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.02.036
更新日期:2010-06-02 00:00:00
abstract::Fiber orientation and ventricular geometry are incorporated in a mathematical model for ejection fraction of the human left ventricle. The inadequacy of circularly oriented or "constrictor" fibers to explain high ejection fractions of cylindrical, spherical, or ellipsoidal reference ventricles is demonstrated. A class...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(69)86429-5
更新日期:1969-07-01 00:00:00
abstract::Using a combination of microelectrode measurements and high-power microscopy we have demonstrated that different Donnan potentials can be recorded from the A- and I-bands of glycerinated and chemically skinned muscles in rigor, so that the A-band fixed charge concentration exceeds the I-band fixed charge concentration...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(85)83760-7
更新日期:1985-07-01 00:00:00
abstract::Purple membranes were adsorbed on freestanding lipid bilayers, termed nano-black lipid membranes (nano-BLMs), suspending the pores of porous alumina substrates with average pore diameters of 280 nm. Nano-BLMs were obtained by first coating the upper surface of the highly ordered porous alumina substrates with a thin g...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.059550
更新日期:2005-08-01 00:00:00
abstract::Fluorescence lifetime imaging microscopy is used to demonstrate that different loads applied to a muscle fiber change the microenvironment of the nucleotide binding pocket of myosin. Permeabilized skeletal muscle fibers in rigor were labeled with a fluorescent ATP analog, 3'-DEAC-propylenediamine (pda)-ATP (3'-O-{N-[3...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.07.052
更新日期:2010-10-06 00:00:00
abstract::Electrically excitable channels were expressed in Chinese hamster ovary cells using a vaccinia virus vector system. In cells expressing rat brain IIA Na+ channels only, brief pulses (< 1 ms) of depolarizing current resulted in action potentials with a prolonged (0.5-3 s) depolarizing plateau; this plateau was caused b...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(93)81153-6
更新日期:1993-09-01 00:00:00
abstract::The photoelectron quantum yields of 21 common amino acids and 15 polyamino acids were measured in the 180-240 nm wavelength region. On the average, the quantum yields of these two groups exhibit quite similar wavelength dependence. For lambda > 220 nm all amino acid and polyamino acid quantum yields are =10(-7) elec...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(74)85927-8
更新日期:1974-06-01 00:00:00
abstract::The structure and alignment of the amphipathic alpha-helical antimicrobial peptide PGLa in a lipid membrane is determined with high accuracy by solid-state 2H-NMR. Orientational constraints are derived from a series of eight alanine-3,3,3-d3-labeled peptides, in which either a native alanine is nonperturbingly labeled...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.073858
更新日期:2006-03-01 00:00:00
abstract::We report here a method for the determination of the pKa of histidine in complex or heterogeneous systems amenable to neither solid-state nor solution NMR spectroscopy. Careful synthesis of a fluorenylmethyloxycarbonyl- and trityl-protected, C2-deuterated histidine produces a vibrational-probe-equipped amino acid that...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2020.09.011
更新日期:2020-11-03 00:00:00
abstract::Tagging of individual proteins with genetically encoded fluorescent proteins (FPs) has been used extensively to study localization and interactions in live cells. Recent developments in single-molecule localization microscopy have enabled the dynamic visualization of individual tagged proteins inside living cells. How...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2016.05.047
更新日期:2016-07-12 00:00:00
abstract::The closed-state crystal structure of prokaryotic inward rectifier, KirBac1.1, has implicated four inner helical phenylalanines near the cytoplasmic side as a possible locus of the channel gate. In the present study, we investigate whether this structural feature corresponds to the physiological pH gate of the renal i...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.051474
更新日期:2005-04-01 00:00:00
abstract::Lipid mixing between vesicles functionalized with SNAREs and the cytosolic C2AB domain of synaptotagmin-1 recapitulates the basic Ca(2+) dependence of neuronal exocytosis. However, in the conventional ensemble lipid mixing assays it is not possible to discriminate whether Ca(2+) accelerates the docking or the fusion o...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.12.3730
更新日期:2011-02-16 00:00:00
abstract::Monolayers prepared from myelin conserve all the compositional complexity of the natural membrane when spread at the air-water interface. They show a complex pressure-dependent surface pattern that, on compression, changes from the coexistence of two liquid phases to a viscous fractal phase embedded in a liquid phase....
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.107.112441
更新日期:2007-12-15 00:00:00
abstract::We have developed a method of performing near-field fluorescence correlation spectroscopy via an array of planarized circular apertures of 50 nm diameter. This technique provides 1 μs and 60 nm resolution on proximal samples, including live cells, without incorporating a scanning probe or pulsed lasers or requiring pe...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.02.034
更新日期:2011-04-06 00:00:00