First report on classical and molecular cytogenetics of archerfish, Toxotes chatareus (Perciformes: Toxotidae)

• Published in: Nucleus (Calcutta) 2017-12, Vol.60 (3), p.349-359
• Main Authors: Supiwong, Weerayuth, Jiwyam, W., Sreeputhorn, K., Maneechot, N., Bertollo, L. A. C., Cioffi, M. B., Getlekha, N., Tanomtong, A.
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Cell Biology; Chromosome number; Chromosomes; Cytogenetics; Fluorescence in situ hybridization; Gene mapping; Kidneys; Life Sciences; Mapping; Nucleoli; Original Article; Perciformes; Probes; Rivers; Toxotes chatareus; Toxotidae
• ISSN: 0029-568X; 0976-7975
• DOI: 10.1007/s13237-017-0216-5

A detailed account of liner delineation of chromosomes of archerfish, Toxotes chatareus (Perciformes: Toxotidae) employing conventional staining, NOR banding and molecular cytogenetics with fluorescence in situ hybridization (FISH) using 5S, 18S rDNAs and microsatellite d(CA) 15 , d(GA) 15 , d(CAA) 10 , d(CGG) 10 , and retrotransposonable Rex6 probes, is presented for the first time. The specimens were collected from the Chao Phraya River, Thailand. The mitotic chromosome preparations were directly carried out from kidney tissues of eight male and female fish each. The results revealed that the diploid chromosome number of T . chatareus was 2 n  = 48, the fundamental numbers (NF) were 50 in both male and female. The karyotype composed of two metacentric and 46 telocentric chromosomes. No irregularly sized chromosomes related to sex were observed. The nucleolar organizer regions (NORs) were detected by Ag-NOR banding and 18S rDNA probe mapping. Both techniques revealed the presence NORs located on the long arm adjacent to the centromere of the single pair of the largest telomeric chromosome pair. The 5S rDNA sequences were located in two large telocentric pairs. One of them is coincident with 18S rDNA sites and another is found at interstitial subcentromeric region of the second telomeric pair. FISH with d(CA) 15 and d(GA) 15 probes showed that hybridization signals are abundantly distributed in all chromosomes, mostly in telomeric regions while d(CAA) 10 and d(CGG) 10 repeats are distributed in all chromosomes with high accumulation throughout the chromosomes in some pairs. Chromosomal mapping of the Rex 6 sequences, indicate a weak distribution in all chromosomes, with preferential accumulation at the centromere of the chromosome pair 7.