A Study on Damage of Chromosomes Activity in Seedlings of Crepis Capillaris - Progress in Organic and Physical Chemistry: Structures and Mechanisms - page 266

were germinating in a thermostat at 25°C, but in July 1968 because of hot weather the
temperature in the thermostat could reach 27°C. In parallel control experiments, the
seeds were treated with aqua distillate.
After 24, 27, and 31 hr, after soaking of seeds we choose “arisings”. The term
“arising” refers to those seedlings that emerge after the beginning of soaking of dry
seeds and have a size of less than 1 mm. These seedlings were selected in a Petri dish
for further germination and subsequent ¿ xation. In Russian the term “arising” is called
“proklev”.
For the analysis of chromosomes in metaphase plates, root tips (0.5-1cm) were —–
with a razor and placed in the —– : 96% ethanol three parts and one part of
glacial acetic acid. Solution poured out through 3-4 hr. Seedlings were washed 45 min
in 70% alcohol. These seedlings were kept in 70% alcohol. We were preparing tempo-
rary pressure preparations: ¿ xed root tips were stained acetous carmine and crushing
in a solution of chloral hydrate between the slide and cover slip. We analyzed chromo-
some aberrations in metaphase plates of seedlings in the ¿ rst division after treatment
of seeds (2 n -karyotype). In each seedling were counted up all metaphases. Intact seeds
of harvest of 1966, 1967, and 1969 years served as control. The seedlings were ¿ xed
at different time intervals from 3 to 24hr.
We analyzed rearrangements of chromosomal type (damage of chromosomes be-
fore beginning of synthesis of DNA) and chromatid type (damage of chromatids with
beginning of synthesis of DNA). Mitotic activity in the seedlings was determined on
two criteria:
(1) On the criterion of the number of metaphase plates, depending on the num-
ber of nuclei in seedlings in the control and experiment (after seed treatment
phosphemid). We used the seedlings after 2, 4, 6, 8, 10, and 20 hr after the
“arising”. In each seedling, we counted between 500 and 1,000 nuclei, in an
each seedling counted from 500 to 1,000 nuclei.
(2) On the criterion of the number of seedlings with metaphase to all watched
seedlings at all stages of fixation.
In all the experiments was estimated standard deviation from the mean.
21.3 DISCUSSION AND RESULTS
The natural level of mitotic activity, control was estimated by the criterion of the num-
ber of metaphases in seedlings of the 18,000 counted nuclei metaphase plates were
2.83 ± 0.12%.
Table 1 shows data within 3 years of the evaluation of natural mitotic activity on
the criterion of the number of metaphases in all investigated roots, in different years
(1966, 1967, and 1969) ranged 90-99%.