Insights into Emydid Turtle Cytogenetics: The European Pond Turtle as a Model Species

Iannucci, Alessio; Svartman, Marta; Bellavita, Massimo; Chelazzi, Guido; Stanyon, Roscoe; Ciofi, Claudio

doi:10.1159/000495833

Cited by 4 publications

(14 citation statements)

References 66 publications

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“…Furthermore, we compared our results for E. trinacris and T. s. scripta with previously published cytogenetic data, specifically with E. orbicularis, T. s. elegans and T. dorbigni [20,21]. Both E. trinacris (this study) and E. orbicularis [21] share identical karyotypes, considering the chromosome morphology. In addition, identical patterns between the two species were also found Furthermore, we compared our results for E. trinacris and T. s. scripta with previously published cytogenetic data, specifically with E. orbicularis, T. s. elegans and T. dorbigni [20,21].…”

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confidence: 66%

“…Both E. trinacris (this study) and E. orbicularis [21] share identical karyotypes, considering the chromosome morphology. In addition, identical patterns between the two species were also found Furthermore, we compared our results for E. trinacris and T. s. scripta with previously published cytogenetic data, specifically with E. orbicularis, T. s. elegans and T. dorbigni [20,21]. Both E. trinacris (this study) and E. orbicularis [21] share identical karyotypes, considering the chromosome morphology.…”

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confidence: 68%

“…For both species, we compared our results with the previously published data on Emys orbicularis [21], Trachemys scripta elegans (Wied 1838) and Trachemys dorbigni (Duméril and Bibron 1835) [19,20,25] in order to expand our knowledge on the karyotype evolution of emydid turtles.…”

Section: Introductionmentioning

confidence: 99%

“…Emydids seem to have similar karyotypes based on chromosome morphology, and their diploid chromosome numbers vary from 2n = 48 to 2n = 52, with 2n = 50 chromosomes (26 macro-and 24 microchromosomes) being the most common [17]. Across five studied emydid species, the expected terminal topology of telomeric repeats was reported in Chrysemys picta [27], E. orbicularis [21], T. s. elegans [25] and T. dorbigni [25], while interstitial telomeric repeats were detected only in the centromeric region of chromosome 9 of Glyptemys insculpta [22].…”

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confidence: 99%

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Molecular Cytogenetic Characterization of the Sicilian Endemic Pond Turtle Emys trinacris and the Yellow-Bellied Slider Trachemys scripta scripta (Testudines, Emydidae)

Scardino

Mazzoleni

Rovatsos

et al. 2020

Genes

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Turtles, a speciose group consisting of more than 300 species, demonstrate karyotypes with diploid chromosome numbers ranging from 2n = 26 to 2n = 68. However, cytogenetic analyses have been conducted only to 1/3rd of the turtle species, often limited to conventional staining methods. In order to expand our knowledge of the karyotype evolution in turtles, we examined the topology of the (TTAGGG)n telomeric repeats and the rDNA loci by fluorescence in situ hybridization (FISH) on the karyotypes of two emydids: the Sicilian pond turtle, Emys trinacris, and the yellow-bellied slider, Trachemys scripta scripta (family Emydidae). Furthermore, AT-rich and GC-rich chromosome regions were detected by DAPI and CMA3 stains, respectively. The cytogenetic analysis revealed that telomeric sequences are restricted to the terminal ends of all chromosomes and the rDNA loci are localized in one pair of microchromosomes in both species. The karyotype of the Sicilian endemic E. trinacris with diploid number 2n = 50, consisting of 13 pairs of macrochromosomes and 12 pairs of microchromosomes, is presented here for first time. Our comparative examination revealed similar cytogenetic features in Emys trinacris and the closely related E. orbicularis, as well as to other previously studied emydid species, demonstrating a low rate of karyotype evolution, as chromosomal rearrangements are rather infrequent in this group of turtles.

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confidence: 66%

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confidence: 68%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Molecular Cytogenetic Characterization of the Sicilian Endemic Pond Turtle Emys trinacris and the Yellow-Bellied Slider Trachemys scripta scripta (Testudines, Emydidae)

Scardino

Mazzoleni

Rovatsos

et al. 2020

Genes

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“…Notably, in some cases, the telomeric motif TTAGGG is part of a larger satellite DNA sequence, and its presence and amplification in the genome is not directly connected to chromosomal rearrangements [ 68 , 69 ]. In turtles, the distribution of telomeric motifs have been studied up to our knowledge in 27 out of the 353 extant species [ 70 , 71 ], but ITRs have been previously reported in only six species [ 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ], reviewed further in this study, but more systematic survey is needed before drawing solid conclusions on the frequency of ITRs in turtles.…”

Section: Introductionmentioning

confidence: 99%

Interstitial Telomeric Repeats Are Rare in Turtles

Clemente

Mazzoleni

Pensabene

et al. 2020

Genes

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Telomeres are nucleoprotein complexes protecting chromosome ends in most eukaryotic organisms. In addition to chromosome ends, telomeric-like motifs can be accumulated in centromeric, pericentromeric and intermediate (i.e., between centromeres and telomeres) positions as so-called interstitial telomeric repeats (ITRs). We mapped the distribution of (TTAGGG)n repeats in the karyotypes of 30 species from nine families of turtles using fluorescence in situ hybridization. All examined species showed the expected terminal topology of telomeric motifs at the edges of chromosomes. We detected ITRs in only five species from three families. Combining our and literature data, we inferred seven independent origins of ITRs among turtles. ITRs occurred in turtles in centromeric positions, often in several chromosomal pairs, in a given species. Their distribution does not correspond directly to interchromosomal rearrangements. Our findings support that centromeres and non-recombining parts of sex chromosomes are very dynamic genomic regions, even in turtles, a group generally thought to be slowly evolving. However, in contrast to squamate reptiles (lizards and snakes), where ITRs were found in more than half of the examined species, and birds, the presence of ITRs is generally rare in turtles, which agrees with the expected low rates of chromosomal rearrangements and rather slow karyotype evolution in this group.

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Comparative Cytogenetics of Four Sea Turtle Species (Cheloniidae): G-Banding Pattern and in situ Localization of Repetitive DNA Units

Machado

Glugoski

Domit

et al. 2020

Cytogenet Genome Res

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Sea turtles are considered flagship species for marine biodiversity conservation and are considered to be at varying risk of extinction globally. Cases of hybridism have been reported in sea turtles, but chromosomal analyses are limited to classical karyotype descriptions and a few molecular cytogenetic studies. In order to compare karyotypes and understand evolutive mechanisms related to chromosome differentiation in this group, Chelonia mydas, Caretta caretta, Eretmochelys imbricata, and Lepidochelys olivacea were cytogenetically characterized in the present study. When the obtained cytogenetic data were compared with the putative ancestral Cryptodira karyotype, the studied species showed the same diploid number (2n) of 56 chromosomes, with some variations in chromosomal morphology (karyotypic formula) and minor changes in longitudinal band locations. In situ localization using a 18S ribosomal DNA probe indicated a homeologous microchromosome pair bearing a 45S ribosomal DNA locus and size heteromorphism in all 4 species. Interstitial telomeric sites were identified in a microchromosome pair in C. mydas and C. caretta. The data showed that interspecific variations occurred in chromosomal sets among the Cheloniidae species, in addition to other Cryptodira karyotypes. These variations generated lineage-specific karyotypic diversification in sea turtles, which will have considerable implications for hybrid recognition and for the study, the biology, ecology, and evolutionary history of regional and global populations. Furthermore, we demonstrated that some chromosome rearrangements occurred in sea turtle species, which is in conflict with the hypothesis of conserved karyotypes in this group.

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Insights into Emydid Turtle Cytogenetics: The European Pond Turtle as a Model Species

Cited by 4 publications

References 66 publications

Molecular Cytogenetic Characterization of the Sicilian Endemic Pond Turtle Emys trinacris and the Yellow-Bellied Slider Trachemys scripta scripta (Testudines, Emydidae)

Molecular Cytogenetic Characterization of the Sicilian Endemic Pond Turtle Emys trinacris and the Yellow-Bellied Slider Trachemys scripta scripta (Testudines, Emydidae)

Interstitial Telomeric Repeats Are Rare in Turtles

Comparative Cytogenetics of Four Sea Turtle Species (Cheloniidae): G-Banding Pattern and in situ Localization of Repetitive DNA Units

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