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Abstract

5S ribosomal DNAs (rDNAs) from two cyprinid species, Acheilognathus tabira subsp. 1 and Cyprinus carpio, were isolated and sequenced. Tandemly arranged rDNAs were 179 bp in A. tabira and 204 bp in C. carpio. The non-transcribed spacer region elucidates the size difference of 5S rDNA between the two species. Fluorescence in-situ hybridization (FISH) localized 5S rDNAs to the short arms of two pairs of chromosomes in A. tabira and two to four pairs in C. carpio. Subsequent analysis demonstrated NORs in one pair of chromosomes in both species. Both the NOR and 5S rDNA are carried by a chromosome pair in A. tabira, but they are located on different chromosomes separately in C. carpio. Karyotype evolution by tetraploidy seems complex in cyprinid species.

Chromosomes of Asian cyprinid fishes: cytogenetic analysis of two representatives of small paleotetraploid tribe Probarbini

“…As an example, the common carp Cyprinus carpio , with a (paleo) tetraploid karyotype 2n = 100, exhibits a re-diploidized pattern for 45S rDNA, with only a single chromosome pair carrying such sites [92, 93]. Also four to eight 5S rDNA loci [94] can be observed there, while in the (paleo-) tetraploid crucian carp Carassius carassius the major rDNA sites occupy two different chromosomal pairs, and the minor rDNA encompasses a variable number of 8–18 loci [29, 30]. Besides, a comparable variability of rDNA distribution was also present in several polyploid forms of C. auratus complex [63, 67, 95].…”

Molecular organization of the 5S rDNA gene type II in elasmobranchs

“…5,59 In bony fishes, a TATA-like box was found between position -20 and -30 upstream from the transcription start site. 13,14,60 This suggests a possible influence on the level of transcription. However, despite the presence of a TATA-like box in Rhizoprionodon (with an AATT motif starting at nucleotide -27) 10 and in Rajiformes (as TACA at nucleotide -25), 9 in both Urotrygon species there is not a TATA-like element within the positions ¡30 and ¡20 (5 0 -TGTGAAGAGGC-3') similar to those reported previously in Rhizoprionodon and Rajiformes.…”

“…The results obtained by mutual information show 5 pairs of positions with scores above the critical value (M ijc %0.212), these positions are (60,18), (112,18), (92,60), (112,60), (60,24) with M ij equal to 0.99, 0.51, 0.24, 0.45, and 0.23, respectively. Moreover, the covariance-like measure shows 3 pairs of positions with values above its critical value (C ijc %0.172), these positions are (18,51), (18,60), and (35,60) with C ij equal to 0.31, 0.49, and 0.44, respectively.…”

“…Moreover, the covariance-like measure shows 3 pairs of positions with values above its critical value (C ijc %0.172), these positions are (18,51), (18,60), and (35,60) with C ij equal to 0.31, 0.49, and 0.44, respectively. Although there is some evidences of the formation of base triples in RNA structures, 82 it is well known that the 5S rRNA structure form only base pairs.…”

“…Although there is some evidences of the formation of base triples in RNA structures, 82 it is well known that the 5S rRNA structure form only base pairs. 83 Given that one nucleotide can join only to another one nucleotide, we opted to choose only the pair position (18,60), since this is the only pair common to the 2 analyses and has the highest score. We used this information to constrain the secondary structure prediction for each haplotype.…”