A Study of Constitutive Heterochromatin and NOR Banding in Three Species of Puntius from the State of Haryana, India

The purpose of the present study was to investigate and compare the karyotypes of three species of Puntius viz. Puntius sarana (Hamilton, 1822), Puntius sophore (Hamilton, 1822) and Puntius ticto (Hamilton, 1822) belonging to family Cyprinidae in terms of chromosomal architecture, banding pattern and number of chromosomes from aquatic ecosystems of Haryana, India. Diploid chromosome no. 50 was observed in all 3 species of Puntius. The chromosomes of 3 species of Puntius showed constitutive heterochromatin at telomeric and centromeric regions of chromosomes.The Ag-NOR (Argyrophilic-Nucleolus Organizer Region) bands were observed on homologous chromosome pair nos. 2, 8 and 14 in P. sophore, pair nos. 2, 9 and 14 in P. ticto. The diploid chromosome number in P. sarana was found to be 2n = 50, 2 pairs of metacentric chromosomes, 3 pairs of subtelocentric and 20 pairs of acrocentric chromosomes. Chromosomal studies on the P. sophore revealed the diploid chromosome number to be 2n = 50, showed 16 pairs of metacentric chromosomes, 5 pairs of submetacentric, 2 pairs of subtelocentric and 2 pairs of acrocentric chromosomes. The diploid chromosome number in P. ticto was found to be 2n = 50, with 15 pairs of metacentric chromosomes, 6 pairs of submetacentric, 2 pairs of subtelocentric and 2 pairs of acrocentric chromosomes. No heteromorphic sex chromosomes were cytologically detected. Variations in chromosomes are observed with respect to earlier studies which may be due to variation in habitat conditions as a result of anthropogenic activities.

Automated summary

The study investigated and compared the karyotypes of three species of Puntius in aquatic ecosystems of Haryana, India. It was found that all three species had a diploid chromosome number of 50 and exhibited constitutive heterochromatin in specific regions of the chromosomes. Additionally, variations in chromosome structure were observed among the three species.