First report on Nucleolar Organizer Regions (NORs) polymorphism and constitutive heterochromatin of Moonlight Gourami, Trichopodus microlepis (Perciformes, Osphronemidae)


  • Patcharaporn Chaiyasan Biology program, Faculty of Science, Khon Kaen University, Muang, Khon Kaen
  • Sumalee Phimphan Biology program, Faculty of Science and Technology, Phetchabun Rajabhat University, Phetchabun
  • Teamjun Sarasan Biology program, Faculty of Science, Khon Kaen University, Muang, Khon Kaen
  • Sippakorn Juntaree Faculty of Interdisciplinary Studies, Khon Kaen University, Nong Khai Campus, Muang, Nong Khai
  • Alongklod Tanomtong Biology program, Faculty of Science, Khon Kaen University, Muang, Khon Kaen
  • Sitthisak Pinmongkhonkul Department of Biology, School of Science, University of Phayao, Muang, Phayao
  • Weerayuth Supiwong Faculty of Applied Science and Engineering, Khon Kaen University, Nong Khai Campus, Muang District, Nong Khai Province 43000



Moonlight gourami, Trichopodus microlepis, karyotype, Nucleolar Organizer Region, constitutive heterochromatin, chromosome


Nucleolar organizer regions (NORs) polymorphism, constitutive heterochromatin and chromosomal analysis of Moonlight gourami, Trichopodus microlepis in Thailand were firstly reported. Specimens were collected from the Chao Phraya and Mekong Basins, Thailand. The mitotic chromosomes were directly prepared from kidney tissues of ten males and ten females. Conventional staining, Ag-NOR banding and C- banding techniques were applied to stain the chromosomes. The results shown that the diploid chromosome number of T. microlepis was 2n=46 and the fundamental number (NF) was 46 in both males and females. The karyotype consisted of 46 telocentric chromosomes classifying as 14 large and 32 medium chromosomes. No heteromorphic sex chromosome was observed in T. microlepis. The results also showed that the interstitial nucleolar organizer regions (NORs) were clearly observed at the long arm of the chromosome pair 7. This is the first report on NORs polymorphism in T. microlepis that a heteromorphic NOR type in one female had a single NOR-bearing chromosome of the chromosome pair 7, whereas 10 males and nine females had two NOR-bearing chromosomes of the chromosome pair 7 with a homomorphic NOR type. Constitutive heterochromatin was located at all centromeres of all chromosome pairs. The karyotype formula of T. microlepis is 2n (46) = Lt14 + Mt32.


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How to Cite

Chaiyasan, P., Phimphan, S., Sarasan, T., Juntaree, S., Tanomtong, A., Pinmongkhonkul, S., & Supiwong, W. (2021). First report on Nucleolar Organizer Regions (NORs) polymorphism and constitutive heterochromatin of Moonlight Gourami, Trichopodus microlepis (Perciformes, Osphronemidae). Caryologia, 74(2), 111-119.




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