Zoological Studies

Vol. 56, 2017

(update: 2017.9.7; 9.25)

Cytogenetics of Two Onychostoma Species in Taiwan by Ag-NOR and 18S rDNA Profiles

Chiao-Chuan Han1,2, Tsair-Bor Yen3, Nian-Cih Chen4, and Mei-Chen Tseng4,*

1National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan. E-mail: hancc@nmmba.gov.tw
2Graduate Institute of Marine Biology, National Dong Hwa University, Hualien 974, Taiwan
3Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung 912, Taiwan. E-mail: tbyen@mail.npust.edu.tw
4Institute of Aquaculture, National Pingtung University of Science and Technology, Pingtung 912, Taiwan. E-mail: mctseng@mail.npust.edu.tw

(Received 5 June 2017; Accepted 5 September 2017; Communicated by Hin-Kiu Mok)

Chiao-Chuan Han, Tsair-Bor Yen, Nian-Cih Chen, and Mei-Chen Tseng (2017) Both Onychostoma barbatulum and O. alticorpus are primary freshwater fish in Taiwan. The former has been developed as an aquaculture species with high economic value, while the latter is a native endemic species in Taiwan. Understanding the cytogenetic information of these two species is necessary for their selected breeding, recovery, and management. In this study, Giemsa staining, silver-binding nucleolar organizer region (Ag-NOR), C-banding, and fluorescence in situ hybridization (FISH) with 18S ribosomal (r)DNA probes were used to analyze the cytogenetic characteristics. Results of Giemsa staining showed that the two Onychostoma species shared the same number of chromosomes, 2n = 50. Respective karyotype formulas of the female and male were 10 m + 22 sm + 10 st + 8 t and 11 m + 22 sm + 10 st + 7 t in O. barbatulum, and 14 m + 18 sm + 8 st + 10 t and 15 m + 18 sm + 8 st + 9 t in O. alticorpus. Karyotypes of both species showed a pair of heteromorphic chromosomes in male fish. Their sex determination should be the XX/XY system. Two pairs of Ag-NORs were found in O. barbatulum, but only one pair occurred in O. alticorpus. C-banding areas were distributed on centromeres or telomeres of some chromosomes. FISH revealed different cytogenetic characters between these two species. The above cytogenetic information will contribute to species identification, population recovery, and advantages for breeding and management in the future.

Key words:Endemic species, Fluorescence in situ hybridization, Karyotype, Sex determination, Species identification.

*Correspondence: Chiao-Chuan Han and Tsair-Bor Yen contributed equally to this work. Tel: +886-8-7703202 ext. 6227. E-mail: mctseng@mail.npust.edu.tw