Petrova N.A. 2024. [Brief review of Сhironomidae and Simuliidae (Diptera) B chromosomes] // Euroasian Entomological Journal. Vol.23. No.4: 209–214 [in Russian, with English summary].
Zoological Institute, Russian Academy of Sciences, Universitetskaya Nab. 1, Saint Pеtersburg 199034 Russia. E-mail: chironom@zin.ru
doi 10.15298/euroasentj.23.04.04
ABSTRACT. Additional chromosomes (supernumerary or Bchromosomes) are often found in plant and animal karyotypes. They do not conjugate with the A-chromosomes or impact on genotype, but are present in the nucleus independently. Their unstable presence in population is the main characteristic of B-chromosomes; these may contain ribosomal genes which result in the development of a functional nucleolus. It is considered that supernumerary chromosomes may present a universal mechanism of adaptation in evolution. However, in most cases the presence or absence of B-chromosomes does not influence the vitality of individuals and has no phenotypic effect. In dipterans they may be presented as disc shape or structureless globules. The frequency of B-chromosomes may be increased under the impact of pollution on water reservoirs.
KEY WORDS: supernumerary chromosomes, Diptera.