BARTHOLOMEW NAGY - PDF Document

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  1. 1-41111. cial failure of the lateral-transmission theory to explain how, contraction, much greater active ten- sion was present during rest through a pas- sive element that remains length. The only way through sarcolemma can explain iso- metric contraction force is transmitted laterally primarily at the tendon-sarcolemma course, this essentially end mission. An anatomical structure to transmit tension from the ends of myofibrils to tendon-cap may not exist. Intermolec- ular forces between these elements or the cohesive strength of water in the interspace are sufficient. These have previously been outlined [H. Lam- port, A. Mauro, and L. Stark, Proc. Intern. Physiol. Cong. 10th (1965)]. tracts resulted crease meteorite weighed approximately much as those used in the previous study (3); all extract was contained in a 1-cm cell. Standard sucrose solutions diluted to give +2.0 mdeg rotation at 546 m,u wavelength +2.0 to +2.1 mdeg readings. The mea- surements on the Orgueil meteorite do not disprove, of course, the possibility that this slight levorotation was caused by terrestrial contaminations. BARTHOLOMEW NAGY Department of Chemistry, University of California, San Diego, La Jolla 92038 a proportional rotations. The this experiment one-fourth in optical for de- Optical Activity in the Orgueil Meteorite in isometric of the used is delivered to the tendon than as In a recent report (1) Hayatsu has independently confirmed our previous finding (2) of fatty acids in the Orgueil carbonaceous meteorite but advanced the view that the observed (3) in Orgueil organic matter was caused by instru- mental artifacts. It was suggested that the Rudolph polarimeters employed in the investigation showed a levo bias at low transmissions. In my opinion optical activity could be avoided if the following points were considered: 1) Hayatsu used a significantly dif- ferent chemical process to extract the meteorite samples for the optical rota- tion measurements: that is, he used ben- zene, methanol, and chloroform sep- arately for extracting samples. The extraction time also dif- fered from the (2, 3). Since the Orgueil contains a variety of compounds different processes can extract different components. Hayatsu copper chromatography, which also al- ters the composition of the by retaining polar molecules from the eluates (5). 2) In the original Orgueil extracts from three stones were found to be levorotatory by three in- dependent operators on three Rudolph polarimeters in three laboratories. Our procedure blanks and synthetic-dye so- lutions containing sulfur showed no op- tical rotation, whereas Hayatsu's The optical density of the synthetic- dye solutions (3) was nearly identical with that of the Orgueil extract. The terrestrial controls measured were dex- trorotatory. Recent a Bendix Polarmatic tropolarimeter gave the following re- sults: Synthetic-dye ing sulfur were optically inactive and did not show spurious the 60- to 100-percent range. An Orgueil meteorite extract did show rotation of -1.7, -2.1, -2.6, -3.3, and -4.1 millidegrees at wavelengths of 588, 546, 476, 445, and 417 my, respectively, in the 70- to 100- percent transmission range. The error in the various experiments was mdeg. Dilution of the meteorite the same lateral transmission slight levorotation saponifiable in effect gave contractile if is Of cap. is trans- debate about this References ideas 1. R. Hayatsu, Science 149, 443 (1965). 2. B. Nagy and M. Biophys. 101, 240 (1963). 3. B. Nagy, M. T. J. Murphy, V. E. Modzeleski, G. Rouser, G. Claus, Colombo, F. Gazzarrini, (1964). 4. M. H. Briggs and G. Mamikunian, Space Sci. Rev. 1, 647 (1963). 5. M. Blumer, Anal. Chem. 29, 1039 (1957). Arch. Biochem. Bitz, C. meteorite the Hennessy, 202, J. Nature U. 228 D. HAROLD LAMPORT original procedure meteorite Department of Pathology, Yale University School of Medicine, New Haven, Connecticut (4), 2 December 1965 13 October 1965 colloidal used Our argument does not rest on any calculation. It rests on the experimen- tal fact that there was a region of sar- colemma tube in the connection be- tween the strain gauge and the part of the muscle fiber still able to con. tract. Since the tube transmitted large active isometric tensions (100 percent of normal in one have been lateral transmission of that tension from sarcoplasm lemma in the uninjured part of the fiber. In these experiments colemma-tube region was only a small percentage of the fiber length, but always included the junction betweeft fiber and tendon at one end. We ob- served that even when the injured fiber was held quite of the fiber shortened a stimulated and stretched this small re- gion of the sarcolemma we have not yet measured this tube stretch and active tension simultane- ously. extracts Sarcolemma: Tension Transmission Street and Ramsey [Science 149, 1379 (1965)] argue that tension developed in the myofibrils of a striated muscle fiber, instead of being transmitted their ends to the tendon-cap, may be transmitted laterally to the sarcolemma and thence to the tendon. Their argu- ment rests on evidence that the sar- colemma and its attachments to myo- plasm are strong enough to bear the stresses of active tension. This, how- ever, something is possible is not to demon- strate that it is actual. A crucial argument against lateral tension transmission is that it fails to explain the development of active iso- metric tension. The sarcolemma passive elastic tube attached along its length to the contractile sarcoplasm. In isometric contraction, length of the passive sarcolemma does not change (it does not scallop at each sarcomere), the tension in no greater than it was during resting length. Even assigning all of the resting elasticity of the muscle fiber to the sarcolemma does not change the cru- (3) the study at case), there must to sarco-- did. the sar- is not persuasive. To show that it experiments recording spec- with solutions contain- taut, the active part little when rotations transmission in is a but tube, saponifiable since the SIBYL STREET ROBERT RAMSE;. it can be Medical College of Virginia, Richmond 23219 + 0.3 ex- 8 December 1965 1846 SCIENCE, VOL. 150