Karyotype analysis and Ag-NOR localization in the Asian swamp eel (Monopterus albus) from Ban Pong District, Ratchaburi Province, Thailand

Kamika Sribenja; Nuntaporn Getlekha

Authors

Kamika Sribenja Department of Biology, Faculty of Science and Technology, Muban Chombueng Rajabhat University, Ratchaburi Province, 70150, Thailand
Nuntaporn Getlekha Department of Biology, Faculty of Science and Technology, Muban Chombueng Rajabhat University, Ratchaburi Province, 70150, Thailand

Keywords:

Monopterus albus, chromosome, karyotype, idiogram

Abstract

This study aimed to analyze the karyotype and standard idiogram of the Asian swamp eel (Monopterus albus) collected from Ban Pong District, Ratchaburi Province, Thailand. A total of nine specimens, comprising four males and five females, were examined. Chromosomes were prepared directly from kidney tissue using the direct method and stained with conventional staining and the Nucleolar Organizer Regions (NORs) banding techniques. The karyotype and standard idiogram were constructed based on computer-assisted image analysis. The results revealed that M. albus possessed a diploid chromosome number of 24 (2n = 24) and a fundamental number (NF) of 26, comprising one pair of acrocentric chromosomes and 11 pairs of uni-armed chromosomes. The karyotype consisted of 2 large acrocentric, 2 large telocentric, and 20 medium telocentric chromosomes, respectively. No chromosomal differences were observed between males and females. Ag-NOR banding analysis demonstrated a single signal located at the telomeric region of the long arm of a telocentric chromosome no. 7 (7a). This study provides supportive cytogenetic evidence contributing to the taxonomic classification of M. albus. Furthermore, the findings serve as baseline information for the conservation of swamp eel genetic resources and future studies on chromosomal evolution. The karyotype formula of M. albus is 2n (24) = L^a₂+L^t₂+M^t₂₀

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