Karyological analysis of the halfmoon triggerfish (Sufflamen chrysopterum) by the conventional and molecular cytogenetic techniques

Abstract

This research aims to analyze the karyotype and other chromosomal characteristics of the halfmoon triggerfish (Sufflamen chrysopterum) from the Gulf of Thailand (Pacific Ocean). Chromosomes were prepared directly from kidney tissue of fish, and employed the conventional and the molecular cytogenetic analyses by 18S and 5S rDNA, together with CA15, GA15, and CAA10 microsatellites as probes. The results showed 2n=46 (46t; NF=46) in both male and female fish, and that the sex chromosomes could not be distinguished from both sexes. The C-positive heterochromatin was found in the centromeric regions of most chromosomes, and NORs localized single pairs which coincide with the location of the 18S rDNA probe on the telocentric chromosome No. 6. Moreover, the luminous signal of 5S rDNA probe was detected at the subcentromeric region of the same telocentric pair. The sign of (CA)15, (GA)15, and (CAA)10 microsatellites is sparsely dispersed along all the chromosomes, especially the (CA)15 sequences which indicates preferential accumulation at the telomeric and subcentromeric site of almost chromosome. Our study also provides additional data on the accumulation of repetitive sequences in the S. chrysopterum. Besides, the chromosomal organization of microsatellite DNAs among triggerfish species is also reviewed.

Keywords

• triggerfish
• chromosome
• repetitive sequences
• fish cytogenetics