PubMed Health⌕ Search

Biomedical subjects

R A Popp

Publications and source records attributed to R A Popp.

At least 73 records · Page 4Linked to original sources
PubMed1976

Radiation-induced mutations at mouse hemoglobin loci.

In experiments designed to detect new mutations affecting hemoglobin, we irradiated the male or female parent in reciprocal crosses of two mouse strains that differ in alleles at the hemoglobin (Hba, Hbb) loci as well as at five other specific loci. Offspring were analyzed for hemoglobin properties (electrophoretic pattern, solubility, crystal pattern), serum albumin differences, erythrocyte lysis, reticulocyte count, and external appearance. Five hemoglobin variants were found among the mutants. In three, the genetic contribution from the irradiated father was not expressed with regard to the alpha-chain; one carried a tandem deuplication (the first known case in the mouse) involving Hbb; and one probably resulted from double nondisjunction of chromosome 7. The finding that major chromosome aberrations can mimic hemoglobin mutations indicates the need, in similar experiments, to follow F1 screening with thorough cytogenetic analysis. The variants in which there is nonexpression of the alpha chain may be the result of small deficiencies or of faults in transcription or translation. Mutation rates based on these three variants are not out of line with earlier specific-locus results, although confidence limits are still wide.

Anemia↗
PubMed1975

tRNA's associated with the 70S RNA of avian myeloblastosis virus.

The distribtuion of various amino acid tRNA's in the 4S RNA components of avian myeloblastosis virus (AMV) and in 4S RNA prepared from chicken cmbryo cells, chicken myeloblasts, and chicken livers was determined. This was done by aminoacylating the 4S RNA samples with a mixture of 17 radioactive amino acids and subsequently identifying the tRNA-accepted amino acids on an amino acid analyzer after deacylation. In embryo cells, myeloblasts, and liver, tRNA's accepting all 1m amino acids were demonstrated. "Free" AMV 4S RNA was characterized by very low quantities of glutamate, valine, and tyrosine tRNA's. RNAs accepting all 17 amino acids, with the exception of tyrosine, were shown to be present in the "70S-associated" 4S RNA which dissociates at 60 C. The bulk of the 70S-associated 4S RNA was dissociated at 60 C at low ionic strength with a concomitant conversion of 70S RNA to 35S RNA. The residual associated 4S RNA was dissociated by further heating of the 35S RNA to 80 C; tryptophan tRNA accounted for greater than 90% of the total amino acid accepting activity in this fraction. The results support other studies in suggesting that tryptophan tRNA may serve as a primer for DNA synthesis in AMV, as has been shown in Rous sarcoma virus.

Amino Acids↗
PubMedDate not supplied

Critical sample sizes for determining the statistical significance of mutation frequencies.

Based on the assumption that the numbers of mutations observed in an untreated and treated sample of individuals are binomial random variables, a method is presented to compute the probability of observing a specific number of mutations as a function of the sample sizes and the number of mutations in the untreated control sample. Knowledge of the true mutation frequencies is not required. The formalism is then used to compute critical sample sizes for testing hypotheses concerning mutation frequencies in the two populations.

Mutagenicity Tests↗
PubMedDate not supplied

Mouse globin gene nomenclature.

A new system of nomenclature for haplotypes, genes, alleles, and mutant alleles in the mouse alpha- and beta-globin gene complexes was formulated at a meeting of workers in the field and is presented here.

Alleles↗