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S Aaronson

Publications and source records attributed to S Aaronson.

At least 37 records · Page 2Linked to original sources
PubMed1978

Fine structure of the cell surface and Golgi apparatus of Ochromonas.

Ochromonas danica has an unusually flexible cell surface capable of producing projections of varying sizes and shapes: large projections, 340-360 nm long, and small projections, 50-110 nm long. These projections have been demonstrated by transmission and scanning electron microscopy; some of them may break off into the medium and be the source of extracellular membranes and vesicles reported in the cell-free O. danica growth medium. Ruthernium red stained the acid mucopolysaccharide layer just outside the cell surface as well as small blebs at the cell surface. The Golgi complex of O. danica, Ochromonas malhamensis, Ochromonas sociabilis and Ochromonas sp. produced small coated vesicles which may move toward and fuse with the plasma membrane. The role of the several vesicles is unknown but possible functions are discussed.

Animals↗
PubMed1977

The cell content and secretion of water-soluble vitamins by several freshwater algae.

Three green algae, Chlamydomonas reinhardii, Chlorella vulgaris and Scenedesmus obliquus, and one blue-green alga, Anabaena cyclindrica, were grown in chemically defined media. All the algae examined contained folates, beta-carotene and vitamins C and E; several of the B-vitamins and vitamin A were found in varying amounts in some but not in all the algae examined. All the green algae secreted significant amounts of folate and biotin and all but Scenedesmus secreted pantothenate into their growth medium; Anabaena secreted folate and pantothenate.

Chlorophyta↗
PubMed1977

Extracellular phosphatases of Chlamydomonas reinhardi and their regulation.

Chlamydomonas reinhardi, cultured under normal growth conditions, secreted significant amounts of protein and carbohydrates but not lipids or nucleic acids. A fivefold increase in light intensity led to a tenfold increase in secreted protein and carbohydrate. Among the proteins secreted was acid phosphatase with a pH optimum at 4.8 like the enzyme in the cells. Phosphorus depleted algae grown on minimal orthophosphate contained and secreted both acid and alkaline phosphatase. The pH optimum of the intracellular alkaline phosphatase was 9.2. When phosphorus-depleted cells were grown with increasing orthophosphate, intra- and extracellular alkaline phosphatase was almost completely repressed and intra- and extracellular acid phosphatase was partially repressed. Extracellular acid and alkaline phosphatase increased with the age of the culture. Electrophoresis indicated only one acid and one alkaline phosphatase in phosphorus-satisfied and phosphorus-depleted cells. Chlamydomonas cells suspended in an inorganic salt solution secreted only acid phosphatase; the absence of any extr-cellular cytoplasmic marker enzyme indicated that there was little, if any, autolysis to account for the extracellular acid enzyme. Phosphorus-depleted cells were able to grow on organic phosphates as the sole source of orthophosphate. Ribose-5-phosphate was the best for cell multiplication, and its utility was shown to be due to the cell's ability to use the ribose as well as the orthophosphatase for cell multiplication.

Acid Phosphatase↗
PubMed1969

Human diploid cell transformation by DNA extracted from the tumor virus SV40.

The DNA isolated from simian virus 40 (SV40) can transform human fibroblast cells in tissue culture. Clonal lines of DNA-transformed human cells have been obtained that have properties characteristic of cells transformed by whole virus. They all contain SV40 T-antigen, and infectious virus can be recovered by cocultivation. This is the first demonstration of a permanent genetic alteration produced in human cells by purified DNA.

Animals↗