EXPERIMENTAL CONSIDERATION OF THE GENETIC EFFECT OF LOW DOSES OF IRRADIATION ON VIABILITY IN DROSOPHILA MELANOGASTER

Technical Report · Fri Oct 31 00:00:00 EST 1958

OSTI ID:4309322

Burdick, A B; Mukai, T

There is much evidence to indicate that the homozygous state of most irradiation induced mutations is deleterious with respect to viability. However, in random mating population, the homozygous tate of a deleterious mutation is not acheived very frequently unless the heterozygous state is associated with higherthan-normal viability. In addition, most of the lation will exist in heterozygous condition, not in the homozygous condition. Therefore, in determining the genetic effect of irradiation on random mating populations, it is much more important to determione the heterozygous mutant effects since most of the population consequence will be manifest from this conditon. Using the complete marked inversion (CMI) technique wo genetically identical except for the fourth chromosome gene pol which was homozygous pol in one line and in vivo from W-126-pol with 0, 75, 150, and 300 r of 1 mm aluminum filtered x rays, collected and discarded the mature sperm and proceeded to siolate in homozygous conditionn (by CMI technique , again) about 80 genomes per treatment from immature-when- irradiated sperm. This yielded about 320 homozygous lines differeing from one another only to the extent of irradiation induced untreated and unmarked by pol but identical with the pol-marked experimental lines except for new irradia-. tion induced mutations, was used as standard competive test background in the viability studies which followed. We double-mated, in the same bottle and indiol males to pol-marked experimental females (to produce polprogeny that were identically heterozygous for a single irradiation produced genome) and to 2-126 females (to produce identically homozygous, pol-heterozygous progeny). The per cent of pol offspring in each of these test cultures was observed as a measure of viability of the irradiation treated genomes in heterozygous condition. The results indicated that the mean viability of all treated and control groups was about the same exwas significantly higher than that of the control. We do not yet wish to attach any general significance to this higher mean viability of the 75r group. The most important and significant observation made was that the genetic variances of all of the irradiatied groups were he control versus treated variance comparison for the 75r group being 96 versus 265. Furthermore, the variance increase of experimental groups was homogeneous that is, not marked gamma a few discrsst viability differences, but by many small differences. These mutations are dominant in the sense that they produce a phenotypic effect in heterozygous condition. The large variance increases produced by these low doses of irradiation inthan would be expected from present estimnates of the rage crease viability when in heterozygous condition. These hiterto unsuspected results call for a reevaluation of our estimates of the genetic effect of low doses of irradiation in random mating populations. They mean that many more mutation, capable of expression in heterozy gous conditions are produced than our previous estimates of gene number and mutation rate would indicate. They mean that the genetic material is far more sensitive to fore been thought, and that the curious nature of these benetifical as detrimental. The results further indicate that the rate of increase in frequency of homozygously detrimental irradiation induced mutation may be much greater than previously expected since their likelihood of being either heterozygously beneficial or accompanied by dominant viability increasing mutations is much greater than formerly considered. (auth)

• Research Organization: Argonne National Lab., Lemont, Ill.; Purdue Univ. Lafayette, Ind.
• NSA Number: NSA-12-014495
• OSTI ID: 4309322
• Report Number(s): A/CONF.15/P/895
• Resource Relation: Other Information: Prepared for the Second U.N. International Conference on the Peaceful Uses of Atomic Energy, 1958. Orig. Receipt Date: 31-DEC-58
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BIOLOGY AND MEDICINE
ALUMINUM
ANIMAL CELLS
ATOMS
CHROMOSOMES
CONFERENCE
CYTOLOGY
DROSOPHILA
ELECTRIC MOMENTS
FILTERS
GENETICS
GONADS
INSECTS
MAGNETIC MOMENTS
MEASURED VALUES
MOMENTUM
MUTATIONS
NUCLEI
POPULATIONS
QUADRUPOLE MOMENTS
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
REPRODUCTION
SENSITIVITY
SEX
SPERM
VARIATIONS
X RADIATION