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F W Robertson

Publications and source records attributed to F W Robertson.

29 records · Page 2Linked to original sources
PubMed1969

Transcription of bacteriophage T4 deoxyribonucleic acid in vitro.

1. RNA was synthesized in vitro from a template of bacteriophage T4 DNA, in the presence of Mn(2+). A comparison was made of the RNA synthesized by purified RNA polymerase from two sources, Micrococcus lysodeikticus and Escherichia coli; these are referred to as Micrococcus cRNA and E. coli cRNA respectively (where cRNA indicates RNA synthesized in vitro by using purified RNA polymerase and a DNA primer). 2. Both types of RNA were self-complementary as judged by resistance to digestion with ribonuclease after self-annealing, Micrococcus cRNA being more self-complementary (40%) than was E. coli cRNA (30%). The cRNA was found to be much less self-complementary if Mg(2+) was present during RNA synthesis instead of Mn(2+). 3. Micrococcus cRNA hybridized with a larger part of bacteriophage T4 DNA than did E. coli cRNA. The E. coli cRNA competed with only part (70%) of the Micrococcus cRNA in hybridization-competition experiments. It is concluded that more sequences of bacteriophage T4 DNA are transcribed by Micrococcus polymerase than by E. coli polymerase. 4. The RNA sequences synthesized by Micrococcus RNA polymerase but not by E. coli RNA polymerase are shown by hybridization competition to compete with specifically late bacteriophage T4 messenger RNA sequences. The relevance of this finding to the control of transcription is discussed. 5. In an Appendix, new methods are described for the analysis of hybridization-saturation and -competition experiments. Particular attention is paid to the effects produced if different RNA sequences are present at different relative concentrations. 6. By using cRNA isolated from an enzymically synthesized DNA-RNA hybrid, it is estimated that, of the DNA that is complementary to cRNA, only about half can become hybridized with cRNA under the experimental conditions used.

Coliphages↗
PubMedDate not supplied

Effects of apoprotein E polymorphism on serum lipoprotein concentration.

Serum concentrations for the cholesterol and triglyceride content of very low density lipoprotein (VLDL) and the cholesterol content of intermediate density lipoprotein (IDL), low density lipoprotein (LDL), and the high density lipoprotein fractions (HDL2), HDL3) were measured in 337 men and women with the apo E phenotype who were born in the Grampian Region of North East Scotland. The subjects' ages ranged from 45 to 60 years (mean, 53 years). Cigarette smoking and alcohol consumption were recorded and were shown to have minor, but suggestive, effects on serum lipoprotein concentrations. The LDL concentration of E-3/2 subjects was compared with the commonest category, E-3/3, and was found to be about 20% lower in men and about 12% lower in women, in whom the VLDL and IDL concentrations were substantially elevated. In E-4/3 women, the serum LDL concentration was about 10% higher than in E-3/3 women, and the other differences were minor. The effect of allelic substitutions differed between the sexes. The relations between C-peptide ratios and serum lipoprotein concentration differed by gender and phenotype. A comparison with earlier estimates of LDL heritability suggests that in this population, a substantial fraction of the genetic variance of LDL is due to segregation at the apo E locus. The implications of this significant finding are discussed.

Age Factors↗