Optical diffraction studies on stimulated single fibres of frog muscle (Hyla caerulea)

1974 ◽  
Vol 30 (4) ◽  
pp. 373-374 ◽  
Author(s):  
J. Borejdo ◽  
P. Mason ◽  
J. Unsworth
Keyword(s):  
Frog Muscle ◽  
Optical Diffraction ◽  
Single Fibres

Heat production by single fibres of frog muscle

1983 ◽  
Vol 4 (2) ◽  
pp. 207-222 ◽  
Author(s):  
N. A. Curtin ◽  
J. V. Howarth ◽  
R. C. Woledge
Keyword(s):  
Heat Production ◽  
Frog Muscle ◽  
Single Fibres

scholarly journals Titin switches from an extensible spring to a mechanical rectifier upon muscle activation

2021 ◽  
Author(s):  
Caterina Squarci ◽  
Pasquale Bianco ◽  
Massimo Reconditi ◽  
Marco Caremani ◽  
Theyencheri Narayanan ◽  
...  
Keyword(s):  
Thin Filament ◽  
Muscle Activation ◽  
Striated Muscle ◽  
Thick Filament ◽  
Frog Muscle ◽  
Motor Responses ◽  
Filament Activation ◽  
Single Fibres ◽  
Myosin Motors ◽  
Stimulation Of

In contracting striated muscle titin acts as a spring in parallel with the array of myosin motors in each half-sarcomere and could prevent the intrinsic instability of thousands of serially linked half-sarcomeres, if its stiffness, at physiological sarcomere lengths (SL), were ten times larger than reported. Here we define titin mechanical properties during tetanic stimulation of single fibres of frog muscle by suppressing myosin motor responses with Para-Nitro-Blebbistatin, which is able to freeze thick filament in the resting state. We discover that thin filament activation switches I-band titin spring from the large SL-dependent extensibility of the OFF-state to an ON-state in which titin acts as a SL-independent mechanical rectifier, allowing free shortening while opposing stretch with an effective stiffness 4 pN nm-1 per half-thick filament. In this way during contraction titin limits weak half-sarcomere elongation to a few % and, also, provides an efficient link for mechanosensing-based thick filament activation.

Sarcomere dynamics during isotonic velocity transients in single frog muscle fibers

1990 ◽  
Vol 259 (2) ◽  
pp. C266-C278 ◽  
Author(s):  
H. L. Granzier ◽  
A. Mattiazzi ◽  
G. H. Pollack
Keyword(s):  
High Velocity ◽  
Fiber Length ◽  
Muscle Fibers ◽  
Length Change ◽  
Frog Muscle ◽  
Optical Diffraction ◽  
Segment Length ◽  
Low Velocity ◽  
Tension Response ◽  
Sarcomere Dynamics

If the load on a tetanized fiber is abruptly changed to a new steady value, the ensuing fiber length change shows the well-known "isotonic velocity transient," in which the velocity oscillates before settling at some steady value. We studied sarcomere dynamics during these transients using two methods: optical diffraction and a segment-length method. Our principal aim was to determine whether these transients might be a reflection of the fact that sarcomere shortening is often found to be stepwise. We found that pauses in sarcomere shortening occurred during the low-velocity phases of the transient and that steps of sarcomere shortening occurred during the high-velocity phases. Thus the isotonic transient appears to arise from the steps. In addition to the isotonic transient, we studied the well-known isometric transient, in which fiber length is abruptly changed, and ensuing tension response is measured. Again, we found that the transient may be a reflection of the stepwise shortening pattern.

scholarly journals Series Elasticity in Frog Muscle as Revealed by Optical Diffraction

1982 ◽  
Vol 35 (6) ◽  
pp. 617
Author(s):  
Julian A Barden ◽  
Peter Mason
Keyword(s):  
Sarcomere Length ◽  
Striated Muscle ◽  
Small Population ◽  
Frog Muscle ◽  
Optical Diffraction ◽  
Muscle Fibres ◽  
Series Elasticity ◽  
Thick Filaments ◽  
Cross Bridges ◽  
Made In

Using an optical diffraction technique, the series elasticity of frog striated muscle fibres was investigated. One source of series elasticity was located in the cross-bridges during the application of either quick stretches or releases of muscle fibres. Evidence is presented here for a second component attributable to a small population of slowly activated sarcomeres. The size of the second component was progressively reduced until it virtually disappeared at a sarcomere length of 3 pm. A third component appears to reside in the thick filaments. Calculation of the elastic energy in the muscle fibres enabled an identification of the source of the energy to be made in terms of the components of the series elasticity. Evidence is presented of a short-range elastic component present in resting fibres.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microdensitometer—computer correlation analysis of ultrastructural periodicity

1978 ◽  
Vol 36 (2) ◽  
pp. 32-33
Author(s):  
D.R. Ensor ◽  
C.G. Jensen ◽  
J.A. Fillery ◽  
R.J.K. Baker
Keyword(s):  
Correlation Analysis ◽  
Background Noise ◽  
Computer Control ◽  
Optical Diffraction ◽  
Screw Thread ◽  
Straight Line ◽  
Computer Storage ◽  
Correlation Process ◽  
Electron Microscope Image ◽  
Fixed Beam

Because periodicity is a major indicator of structural organisation numerous methods have been devised to demonstrate periodicity masked by background “noise” in the electron microscope image (e.g. photographic image reinforcement, Markham et al, 1964; optical diffraction techniques, Horne, 1977; McIntosh,1974). Computer correlation analysis of a densitometer tracing provides another means of minimising "noise". The correlation process uncovers periodic information by cancelling random elements. The technique is easily executed, the results are readily interpreted and the computer removes tedium, lends accuracy and assists in impartiality.A scanning densitometer was adapted to allow computer control of the scan and to give direct computer storage of the data. A photographic transparency of the image to be scanned is mounted on a stage coupled directly to an accurate screw thread driven by a stepping motor. The stage is moved so that the fixed beam of the densitometer (which is directed normal to the transparency) traces a straight line along the structure of interest in the image.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Crystalline order to a resolution of 4.7 A in the sheath of Methanospirilium hungatii: A cross-beta structure

1984 ◽  
Vol 42 ◽  
pp. 214-215
Author(s):  
Murray Stewart ◽  
T.J. Beveridge ◽  
D. Sprott
Keyword(s):  
Cell Wall ◽  
Single Layer ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Tube Axis ◽  
Basic Subunit ◽  
Beta Structure ◽  
Diffraction Patterns ◽  
Protein Treatment ◽  
General Appearance

The archaebacterium Methanospirillum hungatii has a sheath as part of its cell wall which is composed mainly of protein. Treatment with dithiothreitol or NaOH released the intact sheaths and electron micrographs of this material negatively stained with uranyl acetate showed flattened hollow tubes, about 0.5 μm diameter and several microns long, in which the patterns from the top and bottom were superimposed. Single layers, derived from broken tubes, were also seen and were more simply analysed. Figure 1 shows the general appearance of a single layer. There was a faint axial periodicity at 28.5 A, which was stronger at irregular multiples of 28.5 A (3 and 4 times were most common), and fine striations were also seen at about 3° to the tube axis. Low angle electron diffraction patterns (not shown) and optical diffraction patterns (Fig. 2) from these layers showed a complex meridian (as a result of the irregular nature of the repeat along the tube axis) which showed a clear maximum at 28.5 A, consistent with the basic subunit spacing.

Single molecule optical diffraction: A tool for understanding the structure of triple stranded left-hand helical cellulose

1989 ◽  
Vol 47 ◽  
pp. 1024-1025
Author(s):  
George C. Ruben ◽  
William Krakow
Keyword(s):  
Single Molecule ◽  
Helical Structure ◽  
Optical Diffraction ◽  
Maximum Diameter ◽  
Primary Cell Wall ◽  
Cellulose Synthesis ◽  
Left Hand ◽  
Left Handed ◽  
Freeze Dried ◽  
Diffraction Patterns

Tobacco primary cell wall and normal bacterial Acetobacter xylinum cellulose formation produced a 36.8±3Å triple-stranded left-hand helical microfibril in freeze-dried Pt-C replicas and in negatively stained preparations for TEM. As three submicrofibril strands exit the wall of Axylinum , they twist together to form a left-hand helical microfibril. This process is driven by the left-hand helical structure of the submicrofibril and by cellulose synthesis. That is, as the submicrofibril is elongating at the wall, it is also being left-hand twisted and twisted together with two other submicrofibrils. The submicrofibril appears to have the dimensions of a nine (l-4)-ß-D-glucan parallel chain crystalline unit whose long, 23Å, and short, 19Å, diagonals form major and minor left-handed axial surface ridges every 36Å.The computer generated optical diffraction of this model and its corresponding image have been compared. The submicrofibril model was used to construct a microfibril model. This model and corresponding microfibril images have also been optically diffracted and comparedIn this paper we compare two less complex microfibril models. The first model (Fig. 1a) is constructed with cylindrical submicrofibrils. The second model (Fig. 2a) is also constructed with three submicrofibrils but with a single 23 Å diagonal, projecting from a rounded cross section and left-hand helically twisted, with a 36Å repeat, similar to the original model (45°±10° crossover angle). The submicrofibrils cross the microfibril axis at roughly a 45°±10° angle, the same crossover angle observed in microflbril TEM images. These models were constructed so that the maximum diameter of the submicrofibrils was 23Å and the overall microfibril diameters were similar to Pt-C coated image diameters of ∼50Å and not the actual diameter of 36.5Å. The methods for computing optical diffraction patterns have been published before.

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