A centromeric satellite DNA of the unisexual Bacillus atticus (Insecta: Phasmatodea)

In the parthenogenetic Bacillus atticus atticus, widespread over most of the Mediterranean basin, a highly repeated satellite DNA (BaB300) has been detected and analysed. BgI II, Taq I and Alu I restriction enzymes cut 316 bp long repeating units from the BaB300 family. These are non-coding, AT rich and well conserved in the three isolated populations studied. By in situ hybridization, the satellite has been located in the centromeric heterochromatin of a subset of medium- and small-sized chromosomes, including the Xs. Related sequences have been found in the bisexual B. grandii grandii and in its specific hybrid B. whitei (=B. rossius/grandii grandii), while they are absent from B. rossius redtenbacheri. These data support the genetic affinity relationships within the genus Bacillus inferred from morphological, allozymic and karyological data. They also encourage further comparisons among Bacillus hybrids, in order to trace their parental genomes in the hybrid nuclei, and within the B. atticus complex (i.e. additional samples of B. a. atticus and diploid/triploid cytotypes of B. a. carius) to study repetitive DNA turnover in unisexual organisms.