Chromosomal delineation of repetitive DNAs in the Orange-lined triggerfish, Balistapus undulatus (Tetraodontiformes: Balistidae).

The karyotypes and other chromosomal characteristics of the Orange-lined triggerfish (Balistapus undulatus) from the Gulf of Thailand (Pacific Ocean) were studied, using conventional cytogenetic analyses and fluorescence in situ hybridization using 18 S, 5 S rDNA, together with (CA)₁₅, (GA)₁₅, and (CAA)₁₀ microsatellites as probes. The results showed 2n = 42 (42t; NF = 42) in both male and female fish, and that the sex chromosomes could not be distinguished from one another. The centromeric regions in all the chromosomes showed distinct patterns in the distribution of C-positive heterochromatin. The NORs were localized as single pairs, which coincide with the 18 S rDNA probe's location. At the sub-centromeric region of the telocentric chromosome, the 5 S rDNA probe's bright signal was discovered. The (CA)₁₅, (GA)₁₅, and (CAA)₁₀ microsatellites are sparsely distributed along all the chromosomes. Of these, the (GA)₁₅ sequence, exhibits preferential accumulation at the telomere of chromosome pair 18. The study also suggests that species B. undulatus and Odonus niger are karyotypically similar, necessitating the need for detailed analyses of chromosomal rearrangements with sophisticated cytogenetic techniques to elucidate their further differentiation. [ABSTRACT FROM AUTHOR]