Carbohydrate Metabolism in Yeast Accompanying an Inhibition of Cell Division by X-Rays

Abstract

Cell division is readily inhibited in a wide variety of cells by radiation, but the mechanisms by which this inhibition occurs and the metabolic reactions directly affected must yet be found. A preceding report (Spoerl and Looney, 1958) described changes which occurred in phosphorus compounds when division was inhibited in yeast cells by means of X-radiation. Cells continued to grow, and pentosenucleic acid and protein

Phosphorus Metabolism in Yeast Accompanying an Inhibition of Cell Division by X-Rays

“…irradiated cells which is discussed further in another report (Spoerl and Looney, 1958). At the 3.9 kr/hr radiation dose, the cells at 4 and 6 hr were unable to resist osmotic differences when washed in distilled water and lost soluble nitrogen and phosphorus compounds into the wash water.…”

“…Parallel increases in pentosenucleic acid and protein observed in irradiated cells are consistent with current concepts of protein synthesis (Brachet, 1955). The relative increase in these cell components could have been the result simply of a decrease in the proportion of cell carbohydrates (Spoerl and Looney, 1958). Whether the increase is real or apparent, there evidently is no primary inhibitory effect upon the syntheses involved.…”

“…For analysis, cultures were chilled, cells were centrifuged from the medium at 4 C and washed twice with cold distilled water by centrifuging. The cells were then suspended in 100 ml of cold distilled water and the following aliquots removed: 50 ml for phosphorus analysis, 30 ml for carbohydrate analysis (Spoerl and Looney, 1958), two 5-ml samples for dry weight determinations (overnight at 105 C), three 1-ml samples for total carbohydrate, two 1-ml samples for total nitrogen, two 1-ml samples for total phosphorus and 1 ml for cell count. Culture volumes were used which gave generally between 250 and 350 mg of cell dry weight per 100 ml of cell suspension.…”

Glucose Uptake and Dissimilation by X-Irradiated, Starved, and Division-Inhibited Yeast

“…A change in the membrane as a result of irradiation would need to allow leakage of small ions such as K+, while preserving, at least relative to an unirradiated starved young y-east cell, a greater capacity to take up sugar and phosphate (Spoerl et al, 1960). The change evidently would interfere with the capacity of the membrane to participate in cell-wall formation (Spoerl and Looney, 1958b), if this is a normal membrane function (Mitchell, 1959), and possibly in this way interfere with cell division (Spoerl and Looney, 1958b); unused energy apparently would be stored in an increased cellular content of inorganic polyphosphate (Spoerl, Looney, and Kazmierezak, 1959). Increased amounts of uridine diphosphate acetylglucosamine, a possible intermediate in cell-wall formation, in irradiated, division-inhibited yeast cells (Sasala and Spoerl, unpublished data) suggest further that the interference might well be with a contribution the membrane normally makes, although a later intermediate in the structural sequence also could be responsible.…”

“…An average loss occurred of less than 1 % of the total C1402 collected. Glucose was measured with anthrone, by the method used previously (Spoerl and Looney, 1958b).…”