STUDY OF THE BIOLOGICAL EFFECTS OF AMERICIUM 241 ALPHA PARTICLES ON D7 AND RAD 54.3 STRAINS OF YEAST CELLS;
STUDY OF THE BIOLOGICAL EFFECTS OF AMERICIUM 241 ALPHA PARTICLES ON D7 AND RAD 54.3 STRAINS OF YEAST CELLS;
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Date
1998-03
Authors
OKOSI, PAULINUS
NSIKAK
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Abstract
Two strains of yeast cells, the D7 Saccharomyces cerevisiae and Rad
54-3 -(showing temperature repair sensitivity) were irradiated with Americium
241 alpha particles installed in two irradiation geometry. This study investigates
the biological effects of Americium 241 alpha particles emerging from these two
irradiation geometry on the selected strains of yeast cells with reference to the
survival pattern of the two strains after alpha particle irradiation and mutation
phenomenon. Mutation and survival assay for the D7 Saccharomyces
cerevisiae strain and survival assay under repair permissive (23°C) and
restrictive (36°C) for the Rad-54-3 strain were carried out. Mutants from the D7
yeast cell strain screened for mitotic crossing over, leading to gene conversions
and reversions were selected on synthetic complete (SC) medium containing
marker amino salts after three to four days post-irradiation incubation period,
and the mutant frequency was calculated.. Temperature-sensitive yeast cell
strain- Rad 54-3 showing temperature-dependent repair, was assayed for
survival after irradiation with alpha particles from 48 MBq source and screened
for survivors on full nutrient (Agar) medium under incubation in repair
permissive (23°C) and restrictive (36°C) temperatures for four to five days.
Results show over 90% reduction in survival fraction for the D7 yeast cells after
irradiation with alpha particle fluence of 1.513 x 109 particles cm"2. Comparative'
data from the X-ray irradiations yielded a D0 of 180.7Gy for same strain. There
exist a clear distinction in the survival of this strain at the two incubation
temperatures with the following inactivation cross-section:- 36°c = 1-34 urn2;
and <j23*c = 0.74 urn2
Description
A Thesis submitted to
the Post-Graduate School,Ahmadu Bello University, Zaria
in partial fulfilment of the requirements for the award of the
degree of Master of Science (M.Sc.) in Radiation - Biophysics
DEPARTMENT OF PHYSICS
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY(ABU)
ZARIA; - NIGERIA