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R K Selander

Publications and source records attributed to R K Selander.

At least 145 records · Page 8Linked to original sources
PubMed1973

Interaction of quinacrine mustard with mononucleotides and polynucleotides.

1. The interaction between quinacrine mustard and mononucleotides and polynucleotides was investigated by fluorimetry and absorbance spectrophotometry. 2. The fluorescence spectrum of quinacrine mustard is independent of the ionic strength and pH. The dependence of the quinacrine mustard fluorescence intensity on ionic strength, pH and anions is described. 3. The fluorescence intensity of quinacrine mustard was enhanced with the mononucleotide adenylic acid and polynucleotides such as poly(rA), poly(rU) and poly(rA,rU). 4. Quenching of the fluorescence intensity of quinacrine mustard occurred with the mononucleotide guanylic acid and with poly(rG) and poly(rC,rG). 5. The mononucleotide cytidylic acid or poly(rC) showed no effect on the fluorescence intensity of quinacrine mustard. 6. The interaction between the dye and native DNA species was also dependent on the presence of base-specific binding sites in the DNA. The higher the (G+C) content was in the native DNA tested the higher was the quenching effect on the fluorescence intensity of quinacrine mustard. 7. No interaction was found between the dye and methylated DNA. The binding between quinacrine mustard and apurinic DNA was confirmed to be in the phosphate groups of the purines.

Adult↗
PubMed1973

Interaction of quinacrine mustard with calf thymus histone fractions.

1. Interactions of histone fractions with quinacrine mustard were investigated by fluorimetry and spectrophotometry and the results were interpreted with the aid of thinlayer chromatography. 2. Characteristic differences were found between the various histone fractions of calf thymus. The conditions that favoured histone conformational changes and aggregation, also favoured interaction between histones and the dye; low concentrations of SO(4) (2-) brought about more interaction than did Cl(-); urea, guanidinium and iodide ions were inhibitory to binding. 3. Changes in the physical state of all the quinacrine mustard-protein complexes occurred as a function of ionic strength and pH. The most salt-dependent interaction was found in the arginine-rich histone fraction. 4. The interaction of the calf thymus histone fractions with quinacrine mustard was compared with the interaction of bovine plasma albumin and protamine with quinacrine mustard. 5. The relationship between dye-binding and the aggregation of histone fractions was discussed.

Animals↗
PubMed1973

Self-fertilization and genetic population structure in a colonizing land snail.

The pulmonate land snail Rumina decollata in its native Mediterranean range is a complex of monogenic or weakly polygenic strains generated by a breeding system of facultative self-fertilization. One strain colonized North America and now occupies much of the southern United States and northern Mexico. No genetic variation within or among populations in the United States was detected in an electrophoretic analysis of proteins encoded by 25 loci. These findings emphasize the potential for adaptive convergence in the genetic systems of hermaphroditic animals and plants.

Journal Article↗
PubMed1973

Genic variability and strategies of adaptation in animals.

Levels of genic heterozygosity, as measured by surveys of allozymic variation, are much lower in populations of large, mobile animals (most vertebrates) than in those of small, relatively immobile animals (most invertebrates). This difference is not consistent with theories relating variability to population size (species number) or dispersal ability (gene flow), but it is predicted by Levins' theory of adaptive strategies in relation to environmental uncertainty ("grain"). Mobility and degree of homeostatic control apparently are important factors influencing levels of genic heterozygosity in natural populations. The results argue indirectly that at least a major proportion of allozymic variation is maintained by natural selection.

Adaptation, Biological↗
PubMed1970

Horseshoe crab lactate dehydrogenases: evidence for dimeric structure.

D-Lactate dehydrogenase of Limulus polyphemus occurs in six molecular forms, not in five as does the L-lactate dehydrogenase of vertebrates. The electrophoretic pattern of bands in an apparent genetic variant is incompatible with a model of tetrameric molecular structure, and suggests, rather, that the three more anodally migrating isozymes are dimer molecules, the polypeptide subunits of which are encoded by two genetic loci and are not involved in the formation of the lower triad of isozymes.

Animals↗
PubMedDate not supplied

Impact of age and situation-specific experience on maze learning and learning-sensitive open-field parameters in mice.

The effects of age and situation-specific experience on maze learning and learning-sensitive open-field parameters (OFP) in Swiss albino male mice were studied. We tested the mice longitudinally by means of repeated measures and in cross-section by taking independent samples between the ages of 1-16 months. Mice with situation-specific experience improved their performance up to the age of 11 months. For mice lacking prior experience there was a trend toward impaired performance with regard to error scores and running times with increasing age. The ages of 1, 8, and 10 months were most favorable for the occurrence of quantitative maze learning-sensitive OFP changes, and the ages of 1, 3, 4, 8, 9, 10, 12, and 13 months were most favorable for the appearance of qualitative changes. The effect of situation-specific experience was interpreted as indicative of decreased emotionality but increased reactivity to novel stimuli or enhanced territorial behavior at the age of 16 months.

Aging↗