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Biomedical subjects

S W Thorne

Publications and source records attributed to S W Thorne.

At least 19 recordsLinked to original sources
PubMed1982

A method of estimating radial distribution function of protein particles in membranes from freeze-fracture electron micrographs.

A computational method for estimating the radial distribution function of particles seen in electron micrographs of freeze-fractured membranes is presented. The method overcomes the previous difficulty of measurements of this quantity from freeze-fracture electron micrographs--the systematic error due to the finite size of the sample areas in the freeze-fracture. By multiplying the measurements by weights specific to the shape of the sample area, the method lessens the errors due to the boundaries of the area and allows a synthesis of the average radial distribution function from counts over many small separate areas.

Computers↗
PubMed1977

Identification of chlorophyll b in extracts of prokaryotic algae by fluorescence spectroscopy.

Solvent extracts of three different prokaryotic algae from three species of didemnid ascidians contained pigments identified, on the basis of their fluorescence excitation (E)and fluorescence emission (F)spectral maxima (measured in nm) at 77K, as chlorophyll a (E 449, F 678) and chlorophyll b (E 478, F 658). The release of algae on cutting or freezing Diplosoma virens was accompanied by a strong unidentified acid that converted these pigments to pheophytins. This unexpected finding provided further confirmation of the identity of the chlorophylls on the basis of the fluorescence spectra at 77K of pheophytin a (E 415, F 669) and pheophytin b (E 439, F 655). There was no evidence for the presence of the fluorescent bilin pigments found in other prokaryotic blue-green algae. Chlorophyll a/b ratios ranged from 2.6 to 12.0 in algae from different ascidians. The photosynthetic membranes were not organized into appressed thylakoids or grana in the algae from any of the three species of ascidians. The relationship between these observations and those in higher eukaryotic organisms is discussed.

Chlorophyll↗
PubMed1975

Light-dependent absorption and selective scattering changes at 518 nm in chloroplast thylakoid membranes.

The light-induced absorbance change at 518 nm of isolated chloroplasts consists of a rapid phase, and a slow phase which is complete in about 20 sec. The slow component of the 518 nm absorbance change correlates with the light-induced change in 90 degrees light scattering at 518 nm. Both show a similar time course, similar pH dependence with a maximum at pH 6.0, and similar sensitivity to inhibitors and to treatment of the chloroplasts with a low concentration of glutaraldehyde. Their light minus dark difference spectra are similar with maxima at about 520 nm. It is concluded that they are manifestations of the same phenomenon, and the slow absorbance increase at 518 nm is due to enhanced scattering. It is proposed that the light-induced changes in scattering at 518 nm reflect alterations in selective dispersion, due to proton uptake and conformational changes in the chloroplast thylakoid membrane.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗