Karyotypic Variation in Laboratory Lines of Amblyomma cajennense: Aneuploidy and Evidence of an Autosomal Translocation

Abstract

Karyotypic data from 67 individuals of Amblyomma cajennense (F.) representing three inbred lines (M3, M6, and M7) and a laboratory colony indicate the presence of considerable chromosomal variation in two of the lines. The majority of the specimens possessed a diploid number of 21 (20 autosomes and a single X chromosome); however, one of the inbred lines (M6) had diploid numbers ranging from 21 to 24. Chromosome banding data indicate that the additional chromosomes are not supernumerary chromosomes and probably represent duplicated autosomes. Additionally, two of the inbred lines (M6 and M7) had individuals heterozygous for a translocation between the largest autosome and the small autosome bearing the nucleolus organizer region. The potential origin of the observed variation is discussed in light of previous accounts of karyotypic variation in ticks.