ON THE SENSITIVITY OF GERMINATING SPORES OF SCHIZOSACCHAROMYCES POMBE TO X RAYS

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Compt. Rend. Trav. Lab. Carlsberg

OSTI ID:4056810

Ditlevsen, E; Hartelius, V

A heterothallic strain of Schizosaccharomyces pombe was used, which when cultivated as a mixture of the two mnting types on malt-agar, four-spored asci are formed and liberate their spores. Experimerts were carried out in Buerker- Tuerk blood-counting chambers with the spores suspended in wort-gelatin, the chambers receiving a 16,000-r dose of x rays. The viable count (a measure of the resistance to x rays) was defined as the ratio between the number of colonies developed in irradiated and control chambers. Resting spores had a viable count of 5 to 6% and young cells 45 to 50%, showing the cells to be much more resistant to x rays than spores. Attempts were made to follow the developmert of x-ray resistance of spores during germination into young cells. Development of spores in the charabers was observed microscopically, and, at diffe rent germinating stages, chambers with spores were irradiated. During the first 12-hr germinntion period the resistance of spores dropped from an initial viable court value to 5 to 6% to a very low value, 0.2%; thereafter it increased again, and at 16 to 17 hr regained the initial value, The drop in resistance occurred during the initial stage of germination, the swelling phase. The time when initial resistance was regained coincided with the inception of cytoplasmic growth, and during the later stages of germination the resistance increased roughly in proportion with the increase of cytoplasmic matter. The poirt of germination at which the individual spore reached minimum resistance was probably only for a short period of its mitotic cycle, presumably during the prometaphase. Many of the lethally damaged spores were able to undergo part of the germination cycle, showing signs of blocked division mechanism (elongated growth). (BBB)

• Research Organization: Carlsberg Lab., Copenhagen
• NSA Number: NSA-18-017510
• OSTI ID: 4056810
• Journal Information: Compt. Rend. Trav. Lab. Carlsberg, Journal Name: Compt. Rend. Trav. Lab. Carlsberg Vol. Vol: 33
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AGE
BIOLOGY AND MEDICINE
INSTRUMENTS
IRRADIATION
LABORATORY EQUIPMENT
LETHAL DOSE
MEASURED VALUES
MICROSCOPY
MITOSIS
NUMERICALS
PERFORMANCE
RADIATION DOSES
RADIATION INJURIES
RADIOSENSITIVITY
REPRODUCTION
SPORES
STANDARDS
SUSPENSIONS
TESTING
VARIATIONS
X RADIATION
YEASTS