1022-7954/04/4012- © 2004
Russian Journal of Genetics, Vol. 40, No. 12, 2004, pp. 1413–1418. Translated from Genetika, Vol. 40, No. 12, 2004, pp. 1702–1708.
Original Russian Text Copyright © 2004 by Minina, Druzhinin.
One of the principal challenges in ecological genet-
ics is testing the effect of the adverse environmental
factors on the structural integrity and functional state of
human genetic apparatus. In this respect, the studies
carried out in the groups of industrial workers, occupa-
tionally subjected to various industrial mutagens are of
key importance. Very often in these cases it is impossi-
ble to distinguish the main factor, and only complex
negative effect of the industrial environment can de dis-
cussed. For instance, industrial production of the coal
coke is associated with the adverse effects of various
chemical (polycyclic aromatic hydrocarbons, benzene,
phenol, etc.) and physical (noise, vibration, and tem-
perature drops) agents on the human organism.
The presence of the genotoxic effects in the workers
involved in the main operations of coke production was
repeatedly described in Russia and other countries [1–3].
The differences in the individual reactions to toxic
exposure were observed. The reasons for this phenom-
enon, however, are not yet understood. It has been sug-
gested that the differences in the genomic dosages of
active ribosomal genes can play a role in this process.
A possible relationship between the dose of active ribo-
somal genes and the adaptive abilities of the organism
is discussed [4, 5].
It has been demonstrated that comparison of human
genomes relative to the number of active (functioning)
ribosomal genes could be performed using visual semi-
quantitative method determining the sizes of the nucle-
olar organizer regions of the chromosomes after selec-
tive silver nitrate staining .
Nucleolar organizer regions (NORs) are chromo-
somal regions, where ribosomal gene clusters are
located. In humans, NORs are mapped to the short arms
of chromosomes 13, 14, 15, 21, and 22. It was estab-
lished that some NORs in addition to active rRNA
genes also contain clusters of “silent” ribosomal genes
(CSRG), whose sizes correlate with the methylated
rDNA copy number [6, 7].
Identiﬁcation of active rRNA gene copies in NORs
is based on the fact that only NORs that were active
(transcribed) during the interphase preceding the mito-
sis are able to reduce silver nitrate [8, 9]. Ag-NOR vari-
ants were shown to be inherited as independent Mende-
lian characters . Based on this ﬁnding, the total size
of ten Ag-NORs was proposed as a characteristic fea-
ture of an individual karyotype . Lyapunova
[11, 12] suggested the existence of stabilizing selection
maintaining a certain level of active ribosomal genes
dose in human organism.
Here, we present the data on the functional status of
NORs in the employees of the Kemerovo coke plant.
This large plant is one of the main environmental pol-
lutants in Kemerovo. According to the plant sanitary
service, the industrial zone air permanently contains
12 types of polycyclic aromatic hydrocarbons. More-
over, in some cases the benzapyrene concentration was
from two to ﬁve times higher than its maximum permis-
sible concentration. In addition, the air from some
industrial zones contained such toxic compounds as
phenol, benzene, and cyanides. In most of the cases, the
concentration of these substances was substantially
higher than maximum permissible concentrations.
Physical working conditions are characterized as
extremely adverse with regard to noise and vibration
parameters. High genotoxic hazard of the industrial
environment was conﬁrmed by the result of our previ-
ous study, which was focused on analysis of the level of
chromosomal aberrations in the workers of the Koks
AO (Joint Stock Company) .
In the present study, genomic dosages of active
rRNA genes in the group of industrial workers sub-
jected to mutagenic factors during the process of coke
Genomic Dosages of Active rRNA Genes
in Coke-Oven Workers
V. I. Minina and V. G. Druzhinin
Department of Genetics, Kemerovo State University, Kemerovo, 650043 Russia;
e-mail: firstname.lastname@example.org, email@example.com
Received January 30, 2003; in ﬁnal form, October 14, 2003
—Genomic dosage (copy number) of active ribosomal genes was evaluated using visual semi-quanti-
tative method determining the sizes of Ag-NORs in acrocentric chromosomes after selective silver nitrate stain-
ing. A relationship between the length of service and the active ribosomal gene copy number was established:
the highest numbers of active rRNA genes were observed in coke-oven workers with a length of service exceed-
ing 20 years. An inverse relationship between the individual doses of active ribosomal genes and toxicogenetic
susceptibility of the workers to the occupational factors was also revealed.