ZZ-ZW sex chromosome system in the finless eel Dalophis imberbis (Anguilliformes, Ophichtidae)

• Published in: Genetica Vol. 135; no. 3; pp. 283 - 288
• Main Authors: Salvadori, S, Coluccia, E, Cannas, R, Cau, A, Deiana, A. M
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.04.2009; Springer Netherlands; Springer Nature B.V
• Subjects: Animal Genetics and Genomics; Animals; Biomedical and Life Sciences; chromosome banding; Chromosome Mapping; Eels - genetics; Evolutionary Biology; Female; fish; Fish cytogenetics; Human Genetics; In Situ Hybridization, Fluorescence; Karyotype; Karyotyping; Life Sciences; Male; Microbial Genetics and Genomics; Plant Genetics and Genomics; sex chromosomes; Sex Chromosomes - genetics; FISH; Sex chromosomes; Fish cytogenetics; Chromosome banding; Karyotype
• ISSN: 0016-6707; 1573-6857
• DOI: 10.1007/s10709-008-9276-4

The karyotype of the finless eel Dalophis imberbis was investigated by conventional (C and replication banding, CMA₃ fluorescence) and molecular (FISH with 45S rDNA probe) techniques. The diploid chromosome number was 2n = 46 and the karyotype consisted of four pairs of meta-submetacentric and 18 pairs of subtelo-acrocentric autosomes and a pair of sex chromosomes heteromorphic in females, composed by a large subtelocentric Z, and a medium sized acrocentric W chromosome; in males this pair was composed by two large subtelocentric ZZ chromosomes. Multiple NORs have been localized by FISH and have been found to be CMA₃ positive; one of the NORs was located on the W chromosome and it was found transcriptionally active by silver staining. The Z chromosome contained distinct intercalar C-positive heterochromatin and W was almost completely heterochromatic. Our report contributes to the knowledge to the cytotaxonomy of Anguilliformes where differentiated sex chromosomes are reported in about a quarter of the species: both male and female heterogamety as well as a multiple chromosome system have been reported. Moreover, this is the first anguilliform species in which multiple NORs have been reported.