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S HESTRIN

Publications and source records attributed to S HESTRIN.

At least 19 recordsLinked to original sources
PubMed1963

The use of shadow-casting technique for measurement of the width of elongated particles.

A method is described for the estimation of the true width of fibrillar or rod-like structures from electron micrographs of metal-shadowed preparations. The method is based on variations in the image width as a function of the angle (beta) between the long axis of the fibril and the direction of the shadow in the plane of the preparation. The image width when beta = 0 degrees practically represents the real width of the elongated particle but is often indistinguishable from the background. The fibril image width is conveniently measured at beta values between 15 degrees and 90 degrees . The true width is obtained by plotting the image width versus sin beta and extrapolating to beta = 0 degrees . Latex spheres are sprayed with the fibrils or rods to indicate the direction of shadow. Tobacco mosaic virus (TMV) was used as a model structure because of its known constant diameter of 150 A (5). The width (in the case of TMV equal to the diameter) found by the present method was 150 A +/- 8 A.

Electrons↗
PubMed1963

Synthesis of cellulose by Acetobacter xylinum. VI. Growth on citric acid-cycle intermediates.

Gromet-Elhanan, Zippora (The Hebrew University, Jerusalem, Israel) and Shlomo Hestrin. Synthesis of cellulose by Acetobacter xylinum. VI. Growth on citric acid-cycle intermediates. J. Bacteriol. 85:284-292. 1963.-Acetobacter xylinum could be made to grow on ethanol, acetate, succinate, or l-malate. The growth was accompanied by formation of opaque leathery pellicles on the surface of the growth medium. These pellicles were identified as cellulose on the basis of their chemical properties, solubility behavior, and infrared absorption spectra. Washed-cell suspensions prepared from cultures grown on ethanol or the organic acids, in contrast to washed sugar-grown cells, were able to transform citric-cycle intermediates into cellulose. The variations in the substrate spectrum of cellulose synthesis between sugar-grown cells and organic acids-grown cells were found to be correlated with differences in the oxidative capacity of the cells. The significance of the findings that A. xylinum could be made to grow on ethanol on complex as well as synthetic media is discussed from the viewpoint of the whole pattern of Acetobacter classification.

Acetates↗
PubMed1962

Synthesis of cellulose by Acetobacter xylinum. V. Ultrastructure of polymer.

Appearance of cellulose microfibrils in the medium of a suspension of cells of Acetobacter xylinum in buffered glucose solution was preceded by a stage during which the cellulose in the medium was amorphous within the available resolution. The size of the vertical axis of the microfibrils of the bacterial cellulose was found on the basis of measurement of shadow length to be only about 16 A. In good agreement with findings of earlier workers, the size of the lateral axis ("width") of the image of the metal-shadowed cellulose microfibrils was found to be 11 mmicro. After correcting for a large part probably contributed by deposited metal in the observed width of the microfibrils, the real width is estimated roughly to be in the neighborhood of 3 mmicro. To account for the occurrence of diverse morphological elements in the fields and for the fact that the cellulose fibrils are free entities rather than physical appendages of the cell, it is suggested that individual cellulose molecules are released at the cell surface and diffuse into the medium, wherein they finally enter into crystal-line patterns.

Acetobacter↗