Cytogenetic Studies in Glossogobius giuris (Hamilton, 1822) Through NOR-Staining and FISH

Abstract

The Glossogobius giuris (Gobiidae), tank goby a species of goby fish, is native mainly to freshwater and estuaries and has importance in the aquarium trade. It is classified as least concern under IUCN Red List. Live individuals of this species were collected from Loktak Lake in Manipur for cytogenetic investigation to reveal the nucleolar organizer region (NOR) through silver nitrate (AgNO3) and chromomycin A3 (CMA3) staining as well as DAPI staining and single-color fluorescence in situ hybridization (FISH) using 18S rDNA sequence as probe. Analysis of more than 50 metaphase chromosome complement (obtained from colchicine–potassium chloride–Carnoy’s fixation–Giemsa staining procedures) showed the presence of 46 diploid chromosome numbers with all telocentric having fundamental arm number as 46 without any heteromorphic pair. One pairs of silver-stained NORs, situated terminally on the telocentric chromosome, were observed. Similarly, one pair of CMA3-positive sites were observed on the chromosome that suggested abundance of GC-rich repetitive DNAs in this region. One pair of 18S rDNA positive sites was observed on the telocentric chromosomes using FISH. These karyological features can be useful markers in cytotaxonomy and conservation of this species.