Chironomus riparius Meigen, 1804

Michailova, Paraskeva, 2024, Markers in the polytene chromosomes of freshwater Chironomus Meigen (Diptera, Chironomidae) species, Zootaxa 5453 (4), pp. 511-537 : 524-525

Chironomus riparius Meigen

The chromosome set is 2n = 8. AB and CD chromosomes are metacentric, EF—submetacentric G—telocentric. The centromeric regions of all chromosomes are distinct large bands ( Fig. 12 ). The polytene chromosomes of the species have the same band sequence as that of C.piger . They both species are homosequential. The localization of the “basic” sequences in every chromosome arm of the polytene chromosomes is the same as that of C. piger . The markers of chromosome G are the same as that of C. piger . The species is a model species for studying the influence of various environmental pollutants on the genome structure ( Michailova et al. 2012, 2022; Duran et al. 2012). Since the species is easily grown in laboratory conditions, studies were conducted on the influence of various heavy metal ions in different concentrations on the structural-functional organization of its polytene chromosomes ( Michailova et al. 2006). Deletions of BRb and BRc and formations of “pompon” chromosomes G were found only in larvae from the trace metal polluted stations—a good marker for environmental pollution ( Michailova et al. 2022). In the C. riparius larvae from Pancharevo Lake, living in sediments containing high concentrations of Cu, Pb and Zn, salivary gland cells containing somatic rearrangements appeared at a significantly higher frequency (51.92%) ( Ilkova et al. 2007). One hundred and fifty-four individuals were studied.

Collection sites: Sofia: South Park, Bistriza River, Pancharevo Lake : Plovdiv: Maritza River .

Pseudothummi cytocomplex with chromosome arm combinations: AE, CD, BF G.

Figures

FIGURE 12. Polytene chromosomes of Chironomus riparius. The numbers on the chromosome arms indicate the “basic”sequences.The large arrows show the localization of the centromere region. The small arrow on chromosome G indicates the marker sequences required for species identification. BR—Balbiani Ring, NOR—Nuclear Organizer Region. A, B, C, D, E, F, G—arms of the chromosomes. Scale bar, 10µm.