Abstract:
This scientific paper shows the influence of lead nitrate on cellular
division in Lycopersicum esculentum Mill. Lead nitrate treatments were
carried out at three concentrations: 5%, 1% and 0.1%, for 2 and 4 hours,
thus, resulting six experimental variants. Treatments were applied on tomato
root meristems, resulting in chromosome mutations, expressed by metaphases
and ana-telophases. After lead nitrate treatments, chromosomes from
metaphases suffered high condensations, becoming pycnotic. In anatelophases, chromosome bridges, chromosome fragments and multipolar
ana-telophases appeared. In interphases, micronuclei appeared. The
frequency of these chromosome aberration types differed according to
concentration and action time of the chemical agent. Next to the abovementioned chromosome aberrations, picnotic nuclei, which are inert from
genetic viewpoint, appeared at supraunitary rates. Picnotic chromosomes
and picnotic nuclei can be considered as a specific feature of lead nitrate
influence on mytogene cells. This assessment is argued by the fact that
chromosome and nuclei picnotisation was found frequently in the meristems
of other genotypes (Allium cepa and Triticum aestivum), at the same
concentrations and action time of lead nitrate. Furthermore, lead nitrate has
a high inhibiting effect on mitotic division from tomato root meristems,
diminishing significantly the value of mitotic index, proportionally correlated
to lead nitrate concentration and action time. Cells reacted differently to the
chemical agent action, at every mitotic stage. We found an extremely low
frequency of cells in anaphase. This experiment has shown that lead nitrate,
known as an very aggressive polluting agent, has a certain mutagen and
inhibiting potential on mytogene cells.
