Abstract:
The lead acetate is a powerful mutagen agent that determins the
appearance of cells with chromosomal aberrations in plants and also in
animals. It has been studiend the influence of this substance on the
germinated seeds belonging to two species: Larix decidua and Picea abies
from the family Pinaceae. The research pursued the evaluation of the mitotic
index, the frequency of the cells with chromosomal aberrations
comparatively with the cells without genetical mutations,that followed to the
treatment with the mutagenic agent in three different concentrations: 0.1, 0.2
and 0.3%. The time of exposure of the seeds to the influence of the lead
acetate was 12 hours, 24 and 48 hours for each of the three concentrations.
The evolution of the mitotic index for the species Picea abies is
homogeneous, the concentrations of 0,1 and 0,2% of lead acetate determined
the increase of the mitotic index and the 0,3% concentration decreased this
value. In the case of Larix decidua species,it couldn't be established a pattern
of evolution of the mitotic index refering to the concentration of the mutagen
agent. Regardless of the concentration of the lead acetate, the exposure time
of the seeds to the action of the mutagen agent and the species that has been
used,it has been observed that the prophase is the dominant phase of the
mitotic division, followed in the most of the cases by metaphase. The
frequency of the cells with chromosomal aberrations is different at the two
monitorised species. The larch tree proved to be more tolerant to the action
of the mutagen agent than the spruce fir. The frequency of the aberrations
cells at larch tree is between 0,21-3,55% comparatively with the spruce fir
where the range of frequencyis between 0,30-4,89%. The most encountered
tipes of chromosomal aberrations are the bridges, the retardatory
chromosomes, the expelled chromosomes, the fragments, the multipolar A-T
and the micronuclei.
