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P ALBERSHEIM

Publications and source records attributed to P ALBERSHEIM.

7 recordsLinked to original sources
PubMed1963

The use of bismuth as an electron stain for nucleic acids.

Evidence is presented to show that bismuth combines in vitro with the phosphate of nucleic acids in a manner similar to its reaction with inorganic phosphate. When tested under similar conditions, protein exhibited no attraction for bismuth. The results of the in vitro experiments, which are of interest within themselves, may be indirectly applicable to in vivo staining. Dividing cells of onion root tips were fixed in OsO(4), stained with bismuth, and examined in the electron microscope. The electron opacity of cell structures known to contain nucleic acids was enhanced by bismuth, while organelles known to lack appreciable quantities of DNA or RNA showed little, if any, change. Bismuth is particularly effective as a stain for the chromatin material during interphase and for the chromosomes during division.

Bismuth↗
PubMed1960

Stained pectin as seen in the electron microscope.

This paper describes electron microscopic studies on the distribution of pectin within young plant cells. Dark-grown onion roots, from 1 to 3 mm. in length, were used. In order to make the pectic substances selectively dense to electrons, they were first reacted with basic hydroxylamine. This treatment produces pectic hydroxamic acids, which in turn were treated with ferric ion to form insoluble complexes. The tissue was imbedded, sectioned, and then observed by electron microscopy. Dense deposits of iron were found in the region of the middle lamella and in a second area near the surface of the primary wall. Transverse walls of varying maturity were noted. The pectin of the more frequent, immature cross-walls, leads directly into the inner reacting layer of the axillary (longitudinal) wall. The pectin of the more mature transverse walls becomes, on the other hand, intimately associated with the middle lamella pectin of the axillary wall. It is shown that the pectin of the middle lamella represents the hot water-soluble portion of the pectic substance, while the internal layer of the axillary wall and the transverse wall pectin represent the so called residual fraction. Hot versene extraction removes essentially all electron-dense material.

Cell Wall↗