Gene Mapping of 18S and 5S rDNA Genes in the Karyotype of the Three-Spot Gourami Trichogaster trichopterus (Perciformes, Osphronemidae)

Abstract

Ornamental fish culture is important as an economic activity and for biodiversity conservation as well. The species of the genus Trichogaster (Perciformes, Osphronemidae), popularly known as three-spot gourami, are among the several commercial species raised around the world. In the present work, eight specimens of Thrichogaster trichopterus from aquarium trade facilities were analyzed. The karyotype was composed of 23 pairs of subtelo/acrocentric chromosomes. Fluorescent in situ hybridization allowed identifying the 18S ribosomal gene at telomeric region on long arms of the largest acrocentric pair. On the other hand, the 5S rRNA gene is located at a proximal region on a pair of medium-sized chromosomes. Such information is extremely useful in face of the risks of introduction and the development of ornamental fish trade, once many fish species can be identified only by genetic studies.

Classical and molecular cytogenetics of Belontia hasselti (Perciformes: Osphronemidae): Insights into the ZZ/ZW sex chromosome system

“…For comparison with other species in the same family, only one species, T. trichopterus has so far been studied. The present results differ, as the 5S rRNA gene is located at a proximal region on a pair of medium-sized chromosomes, whereas the 18S ribosomal gene is located at the telomeric region on long arms of the largest acrocentric pair (Pazza et al 2009). Moreover, the 18S rDNA signals were located on chromosome pair 13, which is consistent with NORs regions.…”