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Biomedical subjects

P A MARKS

Publications and source records attributed to P A MARKS.

At least 19 recordsLinked to original sources
PubMed1964

HEMOGLOBINS A AND F: FORMATION IN THALASSEMIA AND OTHER HEMOLYTIC ANEMIAS.

Rates of synthesis of hemoglobin A by erythroid cells from thalassemic subjects are markedly decreased. Formation of hemoglobin F, however, proceeds at similar rates in cells from subjects with thalassemia and other types of hemolytic anemias. A mechanism is suggested regarding the altered patterns of hemoglobin synthesis under conditions of erythropoietic stimulation in subjects with and without thalassemia.

Anemia, Hemolytic↗
PubMed1964

ALTERATIONS IN POLYRIBOSOMES DURING ERYTHROID CELL MATURATION.

This communication presents a morphological study of the changes in ribosome content and organization which occur during the maturation of erythroid cells of the phenylhydrazine-treated rabbit. Electron micrographs of thin sectioned nucleated and non-nucleated erythroid cells have been subjected to a quantitative analysis of the distribution of ribosomes as polyribosomes of various sizes and as single ribosomes. The ribosomes of nucleated erythroid cells of marrow are virtually all arranged in the polyribosome configuration consisting of clusters of 2 to 6 individual ribosomes. These cells are the most active in the erythroid series in protein biosynthesis. During maturation to the non-nucleated reticulocyte stage, found in the circulating blood, there is a decrease in protein synthesizing capacity, a fall in total ribosome content, and, more significantly, a decrease in the number and size of polyribosomes. Maturation to the ribosome-free erythrocyte, either under in vitro or in vivo conditions, entails a further decrease in protein synthesis which correlates with a progressive disaggregation of the biosynthetically active polyribosomes into smaller clusters and inactive single ribosomes. Possible models which may account for the stability of the polyribosome and for the mechanism of polyribosome dissociation are discussed.

Animals↗
PubMed1963

Reticulocyte protein synthesis: response of ribosome fractions to polyuridylic acid.

Reticulocyte ribosomes with sedimentation coefficients greater than 100S ("heavy" ribosomes) appear to be considerably more active in hemoglobin synthesis than are 78S ribosomes. When assayed for the ability to synthesize polyphenylalanine in the presence of polyuridylic acid, the 78S ribosomes and "heavy" ribosomes have similar activities. Polyuridylic acid inhibits incorporation by "heavy" ribosomes of amino acids other than phenylalanine.

Amino Acids↗