Effect of environmental pollution on the chromosomal variability of Chironomus riparius Meigen 1804 (Diptera, Chironomidae) larvae from two Piedmont stations
P. Michailova et al., Effect of environmental pollution on the chromosomal variability of Chironomus riparius Meigen 1804 (Diptera, Chironomidae) larvae from two Piedmont stations, GENETICA, 108(2), 2000, pp. 171-180
Different frequencies of chromosomal alterations in salivary gland polytene
chromosomes AB, CD and EF were described in larvae of Chironomus riparius
(syn. Chironomus thummi) from the trace metal-polluted station of Santena o
n the river Banna, near Turin, and from the unpolluted station of Corio (40
Km from Turin) which was taken as a reference area. In a sample of 56 larv
ae from Santena, no specimen with the standard karyotype in all cells of th
e salivary glands was found. Different types of aberrations were found: 33
paracentric and five pericentric inversions, three deficiencies, four ampli
fied sections and one chromatid break. Fifteen out of the 38 inversions and
two amplified sections appeared to be inherited, while all the other aberr
ations were somatic. Most of the aberrations' breakpoints were located on b
oth sides of the centromere regions, where constitutive heterochromatin is
present. Also functional alterations were observed (mainly telomere and cen
tromere decondensations and nine novel puffs). In a sample of 49 larvae of
a population from the well-preserved area of Corio only six somatic and one
inherited paracentric inversions were found. These results suggest that th
e strong destabilization of the genomes of C. riparius larvae from Santena
could be a reaction to the activity of the toxic substances present in the
polluted sediments of the river Banna.