Methods for the measurement of polarization optical properties: I. Birefringence

Taylor, D. Lansing; Zeh, R.

doi:10.1111/j.1365-2818.1976.tb01097.x

Cited by 5 publications

(3 citation statements)

References 23 publications

(14 reference statements)

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“…the polarization dependence of the total light scattering and absorbance, the dichroism, is very small (see below). Thus the use of the quarter-wave plate makes the retardation measurements very insensitive to dichroism, and for the purposes of the present measurements To = T90 and R = sin q (Taylor & Zeh, 1976). If a compensator is present, and introduces a retardation 0 as in the previous section:…”

Section: Continuous Measurement Of Optical Retardationmentioning

confidence: 88%

Birefringence changes associated with isometric contraction and rapid shortening steps in frog skeletal muscle fibres.

Irving

1993

The Journal of Physiology

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SUMMARY1. Muscle birefringence, the difference between the refractive indices of light polarized parallel and perpendicular to the muscle fibre axis, was measured at 3°C in intact single fibres isolated from frog muscle. Resting birefringence was 2-20+002 x 10-3 (mean+s.E.M., n = 44) at sarcomere length 2-4-2-7 Jim and 2-35+0-03 x 10-(n = 19) at 3-5-3-8 ,im.2. Birefringence decreased during isometric twitch or tetanic contractions. The peak change in a twitch at sarcomere length 2-6 ,tm, determined by two independent methods, was 0-150 + 0-017 x 10-3 (mean +S.E.M., n = 6). The corresponding value after 0-4 s of tetanic stimulation was 04167 + 0-012 x 1O-' (n = 6).3. The birefringence change had a shorter latency than tension and reached its half-maximum value earlier than tension. The difference in time to half-maximum in tetani was 1 1 5 + 1 3 ms (mean + S.E.M., n = 6) at 3 'C. After stimulation birefringence recovered to its pre-stimulus baseline more slowly than tension.4. The birefringence decrease after 0 4 s of tetanic stimulation was linearly related to the expected degree of overlap between actin and myosin filaments in the sarcomere length range 2-6-3-6 ,tm. The amplitude of the birefringence decrease at full filament overlap (sarcomere length 2-2 ,tm) was estimated to be 0-235 + 0-015 x 10-3.5. Birefringence changes associated with shortening steps of 0'9 % fibre length at sarcomere length 2-6 ,tm exhibited four phases corresponding to those of the tension transient. There was no consistent birefringence change during the length step itself. During the rapid tension recovery birefringence increased by 0-014 + 0-001 x 10-3 (n = 3), measured from the end of the length step to 2 ms later. Birefringence continued to increase as tension recovery slowed, reaching a peak about 10 ms after the step, then recovered with a rate similar to that of the final tension recovery.6. These birefringence changes are likely to be caused by axial rotation of the head domain of the myosin cross-bridge. During isometric contraction heads bind to actin with their long axes more perpendicular to the fibre axis than in resting muscle, although there is likely to be a wide range of head orientations during contraction. The small birefringence increase during the rapid tension recovery following a MS 1726

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Section: Continuous Measurement Of Optical Retardationmentioning

confidence: 88%

Birefringence changes associated with isometric contraction and rapid shortening steps in frog skeletal muscle fibres.

Irving

1993

The Journal of Physiology

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“…Y.). Birefringence measurements were made with a new birefringence detection system: the Polar Eye (65,62). Strain birefringence was induced in the extracts placed in observation chambers.…”

Section: Measurement Ofmentioning

confidence: 99%

The contractile basis of amoeboid movement: V. The control of gelation, solation, and contraction in extracts from dictyostelium discoideum

Condeelis¹,

Taylor²

1977

The Journal of Cell Biology

195

153

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Motile extracts have been prepared from Dictyostelium discoideum by homogenization and differential centrifugation at 4~ in a stabilization solution (60). These extracts gelled on warming to 25~ and contracted in response to micromolar Ca ++ or a pH in excess of 7.0. Optimal gelation occurred in a solution containing 2.5 mM ethylene glycol-bis(/3-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA), 2.5 mM piperazine-N-N'-bis[2-ethane sulfonic acid] (PIPES), 1 mM MgCI2, 1 mM ATP, and 20 mM KCI at pH 7.0 (relaxation solution), while micromolar levels of Ca ++ inhibited gelation. Conditions that solated the gel elicited contraction of extracts containing myosin. This was true regardless of whether chemical (micromolar Ca ++, pH >7.0, cytochalasin B, elevated concentrations of KC1, MgCl2, and sucrose) or physical (pressure, mechanical stress, and cold) means were used to induce solation. Myosin was definitely required for contraction. During Ca ++-or pH-elicited contraction: (a) actin, myosin, and a 95,000-dalton polypeptide were concentrated in the contracted extract; (b) the gelation activity was recovered in the material squeezed out the contracting extract; (c) electron microscopy demonstrated that the number of free, recognizable F-actin filaments increased; (d) the actomyosin MgATPase activity was stimulated by 4-to 10-fold.In the absence of myosin the Dictyostelium extract did not contract, while gelation proceeded normally. During solation of the gel in the absence of myosin: (a) electron microscopy demonstrated that the number of free, recognizable F-actin filaments increased; (b) solation-dependent contraction of the extract and the Ca++-stimulated MgATPase activity were reconstituted by adding purified Dictyostelium myosin. Actin purified from the Dictyostelium extract did not gel (at 2 mg/ ml), while low concentrations of actin (0.7-2 mg/ml) that contained several contaminating components underwent rapid Ca++-regulated gelation.These results indicated: (a) gelation in Dictyostelium extracts involves a specific Ca++-sensitive interaction between actin and several other components; (b) myosin is an absolute requirement for contraction of the extract; (c) actin-myosin interactions capable of producing force for movement are prevented in the gel,

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“…Another electronic method for retardation measurement is the symmetrical angle method, for example, phase modualtion microspectrophotometry [Allen et al, 1963;Allen et al, 19661. This method can also achieve a sensitivity of 0.01 nm with a time constant of 1 second and is considerably less sensitive to stray light [see Zeh, 1976, andHiramoto et al, 1981a, for additional electronic methods]. Electronic methods in general have the advantage that speed and accuracy can be traded off against one another by adjusting the instrumental time constant.…”

Section: Detection Of Microtubules As It Relates To the Sensitivity Omentioning

confidence: 99%

Flow birefringence of microtubules and its relation to birefringence measurements in cells

Hard

Allen

1985

Cell Motility

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Understanding the molecular basis of mitotic movements in living cells will require correlative experiments on intact cells, cell models, purified tubulin, and perhaps other biopolymers. Birefringence is one assay that is useful in all of these experimental situations. Heretofore, studies of birefringence changes during mitosis have lacked a quantitative basis for interpretation in terms of microtubule number and packing density. One of the aims of this work was to establish that relationship. Purified calf brain tubulin was polymerized to equilibrium and oriented in the hydrodynamic field of a microcapillary flow birefringence apparatus. The relationship between birefringence and microtubule packing density was determined by a combination of optical, electron microscopic, and biochemical methods. The data correlate surprisingly well with those obtained by others from in vitro measurements on isolated mitotic spindles. Using the flow birefringence data, the sensitivity of polarizing microscopes for detecting microtubules was examined and found to depend on microtubule packing density, object thickness, and instrumental factors that limit both the detection and measurement of weakly birefringent objects. Because of the dependence of measurement sensitivity on object thickness, a method of measuring the thickness of microtubule bundles using the dispersion of birefringence was developed. This method is capable of measuring thickness to within two or three Airy diffraction units and does not require any assumptions regarding object symmetry.

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Methods for the measurement of polarization optical properties: I. Birefringence

Cited by 5 publications

References 23 publications

Birefringence changes associated with isometric contraction and rapid shortening steps in frog skeletal muscle fibres.

Birefringence changes associated with isometric contraction and rapid shortening steps in frog skeletal muscle fibres.

The contractile basis of amoeboid movement: V. The control of gelation, solation, and contraction in extracts from dictyostelium discoideum

Flow birefringence of microtubules and its relation to birefringence measurements in cells

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