Salvadori S, Coluccia E, Cannas R, Cau A, Deiana A M
Dipartimento di Biologia animale ed Ecologia, Università di Cagliari, Viale Poetto 1, 09126, Cagliari, Italy.
Genetica. 2009 Apr;135(3):283-8. doi: 10.1007/s10709-008-9276-4. Epub 2008 May 26.
The karyotype of the finless eel Dalophis imberbis was investigated by conventional (C and replication banding, CMA(3) 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 CMA(3) 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.
采用常规技术（C带、复制带、CMA(3)荧光）和分子技术（用45S rDNA探针进行荧光原位杂交，FISH）对无鳍鳗Dalophis imberbis的核型进行了研究。其二倍体染色体数为2n = 46，核型由四对中着丝粒 - 亚中着丝粒染色体和18对近端着丝粒 - 端着丝粒常染色体以及一对在雌性中异型的性染色体组成，由一条大的近端着丝粒Z染色体和一条中等大小的端着丝粒W染色体组成；在雄性中，这一对由两条大的近端着丝粒ZZ染色体组成。通过FISH定位了多个核仁组织区（NORs），并发现它们是CMA(3)阳性的；其中一个NOR位于W染色体上，通过银染发现其具有转录活性。Z染色体含有明显的居间C阳性异染色质，而W染色体几乎完全是异染色质。我们的报告有助于了解鳗鲡目鱼类的细胞分类学，在大约四分之一的物种中报道了分化的性染色体：已报道了雄性和雌性异配性别以及多染色体系统。此外，这是首个报道有多条NORs的鳗鲡目物种。
