Biomedical subjects

K L Soderberg

Publications and source records attributed to K L Soderberg.

3 recordsLinked to original sources

PubMed1980

Evolution in Pseudomonas fluorescens.

The relationships among 93 strains of Pseudomonas fluorescens were investigated by (1) a numerical taxonomic analysis on the results of 150 phenotypic tests, (2) DNA hybridization studies using 16 reference strains, (3) quantitative microcomplement fixation studies using six reference strains with antibodies directed against the protein azurin. In general, the strains fell into distinct clusters. Assignment to these clusters on the basis of azurin immunological similarity showed 98% agreement with assignment based on DNA homology, suggesting that many genes will follow the same pattern. Of the strains that clustered on the basis of genotype (DNA, azurin) 88% also clustered on the basis of phenotype. The occasional noncongruency observed between the genotypic and phenotypic data may be due to the variable rates of phenotypic evolution. These results provide a perspective on the roles of horizontal and vertical transfer of genes in the evolution of this bacterial group.

Azurin↗

PubMed1977

Mammalian cells with defective mitochondrial functions: a Chinese hamster mutant cell line lacking succinate dehydrogenase activity.

A mutant cell line derived from Chinese hamster fibroblasts is described which is defective in oxidative energy metabolism. Glucose is continuously required in the medium. As a result of a block in the Krebs cycle, these cells are auxotrophs for carbon dioxide and asparagine. Several experiments support our conclusion that the mutant cells lack appreciable levels of succinate dehydorgenase activity. Other components of the electron transport chain appear to be fully functional, although there is the possibility that electron transport and oxidative phosphorylation are uncoupled.

Animals↗

PubMed1975

Immunological comparison of azurins of known amino acid sequence. Dependence of cross-reactivity upon sequence resemblance.

To examine further the dependence of immunological cross-reactivity on sequence resemblance among proteins, we carried out micro-complement fixation studies with rabbit antisera to bacterial azurins of known amino acid sequence. There is a strong correlation (r = 0.9) between number of amino acid substitutions and degree of antigenic difference (immunological distance) among these azurins. The antigenic effects of amino acid substitutions are thus approximately equal and approximately additive. Similar observations and inferences were made before with a series of bird lysozymes. Indeed, the same approximate relationship between immunological distance (y) and percent difference in amino acid sequence (x) holds for both azurins and lysozymes, namely y congruent to 5x. An explanation is given for the dependence of immunological cross-reactivity on sequence resemblance among proteins. This entails reviewing evidence regarding the nature and number of antigenic sites on globular protein antigens as well as evidence for the existence of evolutionary biases against substitutions that are internal or cause large conformational changes. The explanation we give may apply only to those naturally occurring, globular, monomeric, isofunctional proteins whose sequences differ substantially from that of any rabbit protein.

Amino Acid Sequence↗