The karyology of the Antarctic whelk, Neobuccinum eatoni (Mollusca, Neogastropoda).

Karyotype, location of the nucleolar organizer regions (NORs) and heterochromatin presence and composition were studied in the Antarctic whelk Neobuccinum eatoni. The karyotype exhibits 2n = 68 chromosomes with 10 pairs of metacentrics, 14 pairs of meta‐submetacentrics, six pairs of submeta‐subtelocentrics, and one pair of subtelo‐telocentrics. Silver and CMA3/methyl green staining and rDNA FISH evidenced telomeric NORs on the long arm of a pair of medium‐sized submetacentrics. Staining with AT‐specific fluorochromes evidenced telomeric bands on nearly all chromosomes and interstitial Q bands on two pairs of presumably subtelocentric chromosomes. The karyological evolution of N. eatoni seems to be characterized by a generalized neogastropod karyotype associated with a genome size increase following the accumulation of heterochromatin containing AT‐rich repetitive DNA; according to some authors the latter could be related to the modulation of morphological and functional parameters of ecological significance. [ABSTRACT FROM AUTHOR]