engleski

Comparative chromosomal studies of three Croatian endemic fish species from Leuciscinae subfamily

Karyotypes of three Croatian endemic fish species, two from Krka River, illyric dace (Squalius illyricus) and zrmanja dace (Squalius zrmanjae) and one from Cetina River, ukliva dace (Telestes ukliva) were cytogenetically analyzed. Determination of chromosome number, morphology, determination of chromosome’ s arms (NF number) and localization of GC - rich heterochromatin DNA by fluorescent staining with chromomycin A3 (CMA) were made for the first time. Position of nucleolar organizer regions (NORs) by silver staining (Ag) and DAPI fluorescent staining was made only for T. ukliva. The chromosome complement in all investigated specimens consisted of diploid chromosomes number 2n = 50 with easily recognizable largest chromosome pair which is typical for Leuciscinae subfamily. Total number of chromosome arms in the complement was NF = 96 for T. ukliva, and NF = 92 for S. illyricus and S. zrmanjae. Staining with Chromomycin A3 (CMA) revealed four CMA-positive signals at a telomeric position on the shorter arm of two submetacentric chromosome pairs for T. ukliva, while AT-rich heterochromatic blocks were not detected after staining with DAPI. After silver staining, four active nucleolar organizer regions (Ag-NORs) that correspond to four CMA-positive signals were recorded. S. illyricus and S. zrmanjae revealed two CMA-positive signals at a telomeric position on the shorter arm of one submetacentric chromosome pairs with a notice of difference in size and intensity in S. illyricus between these signals. Cytogenetic analysis of these species will provide us data base for determination of interspecies relations between morphologically similar species as well as assessment of taxonomic and phylogenetic relationships. Due to disarrangement and great number of endemic and endangered species in Croatian ichthyofauna, significance of this research is even greater

chromosomes; Leuciscinae; endemic fish; CMA

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