Extra nucleolar activity associated with presence of a supernumerary chromosome segment in the grasshopper oedipoda fuscocincta

Abstract

The standard males of Oedipoda fuscocincta show a single active nucleolus organiser region (NOR) located in the secondary constriction of the M9 chromosomes. Nine males from three different populations proved to be heterozygous for a heterochromatic supernumerary segment which is distally located on the S10 chromosome. This also showed NOR activity. All available data seem to support the hypothesis that this extra segment on the S10 chromosome has arisen by translocation of part of the M9 chromosome, specifically that located between the centromere and the secondary constriction. © 1986 The Genetical Society of Great Britain.