摘要
The family Sciaenidae is remarkable for its species richness and economic importance. However, the cytogenetic data available in this fish group are still limited, especially those obtained using fl uorescence in situ hybridization(FISH). In the present study, the chromosome characteristics of a sciaenid species, Argyrosomus amoyensis, were examined with several cytogenetic methods, including dual-FISH with 18 S and 5 S rDNA probes, and a self-genomic in situ hybridization procedure(Self-GISH). The karyotype of A. amoyensis comprised 2 n=48 acrocentric chromosomes. A single pair of nucleolar organizer regions(NORs) was located at the proximal position of chromosome 1, which was positive for silver nitrate impregnation(AgNO_3) staining and denaturation-propidium iodide(DPI) staining but negative for Giemsa staining and 4',6-diamidino-2-phenylindole(DAPI) staining, and was confi rmed by FISH with 18 S rDNA probes. The 5 S rDNA sites were located at the centromeric region of chromosome 3. Telomeric FISH signals were detected at all chromosome ends with dif ferent intensities, but internal telomeric sequences(ITSs) were not found. Self-GISH resulted in strong signals distributed at the centromeric regions of all chromosomes. C-banding revealed not only centromeric heterochromatin, but also heterochromatin that located on NORs, in interstitial and distal telomeric regions of specifi c chromosomes. These results suggest that the karyotype of Amoy croaker was relatively conserved and primitive. By comparison with the reported cytogenetic data of other sciaenids, it can be deduced that although the karyotypic macrostructure and chromosomal localization of 18 S rDNA are conserved, the distribution of 5 S rDNA varies dynamically among sciaenid species. Thus, the 5 S rDNA sites may have different evolutionary dynamics in relation to other chromosomal regions, and have the potential to be ef fective cytotaxonomic markers in Sciaenidae.
The family Sciaenidae is remarkable for its species richness and economic importance. However, the cytogenetic data available in this fish group are still limited, especially those obtained using fl uorescence in situ hybridization（FISH）. In the present study, the chromosome characteristics of a sciaenid species, Argyrosomus amoyensis, were examined with several cytogenetic methods, including dual-FISH with 18 S and 5 S rDNA probes, and a self-genomic in situ hybridization procedure（Self-GISH）. The karyotype of A. amoyensis comprised 2 n=48 acrocentric chromosomes. A single pair of nucleolar organizer regions（NORs） was located at the proximal position of chromosome 1, which was positive for silver nitrate impregnation（AgNO_3） staining and denaturation-propidium iodide（DPI） staining but negative for Giemsa staining and 4＇,6-diamidino-2-phenylindole（DAPI） staining, and was confi rmed by FISH with 18 S rDNA probes. The 5 S rDNA sites were located at the centromeric region of chromosome 3. Telomeric FISH signals were detected at all chromosome ends with dif ferent intensities, but internal telomeric sequences（ITSs） were not found. Self-GISH resulted in strong signals distributed at the centromeric regions of all chromosomes. C-banding revealed not only centromeric heterochromatin, but also heterochromatin that located on NORs, in interstitial and distal telomeric regions of specifi c chromosomes. These results suggest that the karyotype of Amoy croaker was relatively conserved and primitive. By comparison with the reported cytogenetic data of other sciaenids, it can be deduced that although the karyotypic macrostructure and chromosomal localization of 18 S rDNA are conserved, the distribution of 5 S rDNA varies dynamically among sciaenid species. Thus, the 5 S rDNA sites may have different evolutionary dynamics in relation to other chromosomal regions, and have the potential to be ef fective cytotaxonomic markers in Sciaenidae.
基金
Supported by the National Natural Science Foundation of China(No.31272653)
the Natural Science Foundation of Fujian Province(No.2017J01449)
the Foundation for Innovation Research Team of Jimei University(No.2010A02)
