Different genomic evolutionary rates in the various reptile lineages

Olmo, Ettore; Capriglione, Teresa; Odierna, Gaëtano

doi:10.1016/s0378-1119(02)00685-6

Cited by 31 publications

(33 citation statements)

References 44 publications

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“…It is also interesting to point out that we found a small difference in GC level at both the global sequence and at the stem level between polar and tropical/temperate fishes, and that this difference is accompanied by differences in the DNA methylation level (Varriale and Bernardi 2006a). Reptiles seem to be in an intermediate position, in agreement with previous results on their genomes that concerned nucleotide composition, band asymmetry in cesium chloride, compositional heterogeneity (for review, see Bernardi 2005), karyotypic evolutionary rates (Olmo et al 2002;Olmo 2005), and DNA methylation (Varriale and Bernardi 2006b).…”

Section: Discussionsupporting

confidence: 91%

Compositional properties and thermal adaptation of 18S rRNA in vertebrates

Varriale

Torelli²,

Bernardi³

2008

RNA

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In order to investigate the influence of temperature on the GC level of the paired sequences of ribosomal 18S RNAs in vertebrates, we have studied their base composition in cold-and warm-blooded vertebrates using a stem-by-stem comparison. We observed that a number of stems of 18S ribosomal RNAs (rRNAs) are variable among species and that the majority of such stems are GC richer in warm-blooded than in cold-blooded vertebrates. We also constructed the secondary structures of the 18S rRNAs of a polar fish, a marsupial, and a monotreme to compare them with those of temperate/tropical fishes and of eutherians, respectively. In these cases, differences similar to those already mentioned were found. We conclude that there is a correlation between stem stability and body temperature even within the relatively limited temperature range of vertebrates.

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Section: Discussionsupporting

confidence: 91%

Compositional properties and thermal adaptation of 18S rRNA in vertebrates

Varriale

Torelli²,

Bernardi³

2008

RNA

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“…Such differences between turtles, crocodiles and squamates may stem from a greater tendency of turtles to preserve and accumulate repetitive DNAs (Olmo, 1984;Olmo et al, 2002), this is consistent with the report by FitzSimmons et al (1995), who found homologous microsatellite loci in non-related marine and freshwater turtles indicating the conservation of flanking sequences spanning approximately 300 million years of divergent evolution. Vice versa, deletions limiting the accumulation of functionally dispensable DNAs would be more frequent in squamates (Olmo et al, 2002).…”

Section: Discussionsupporting

confidence: 91%

“…In particular chelonians, and to some extent crocodiles, show a large and more variable genome size, with quantitative differences also in single-copy DNA (probably in a non-coding fraction), and in repetitive DNA fractions with heterogeneous composition (middle repetitive DNA), whose variations bear no relationship with phylogenesis. By contrast, lizards and snakes show small and more consistent genome sizes, where single-copy DNA is constant and differences mainly depend on the amount of highly repetitive DNA (satellite DNA) (Olmo et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…They are endowed with a range of genome sizes that are similar to that found in mammals (Olmo et al, 2002); in terms of genome composition, they share some characteristics with amphibians and fish, like the prevalence of AT-rich isochores, and others with birds and mammals, like the methylation level (Jabbari et al, 1997;Hughes et al, 2002).…”

Section: Introductionmentioning

confidence: 98%

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Reptiles: a group of transition in the evolution of genome size and of the nucleotypic effect

Olmo¹

2003

Cytogenet Genome Res

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A comparison between genome size and some phenotypic parameters, such as developmental length and metabolic rate, showed in reptiles a nucleotypic correlation similar to the one observed in birds and mammals. Indeed, like homeotherms, reptiles exhibit a highly significant, inverse correlation of genome size with metabolic rate but unlike amphibians, no relationship with developmental length. Several lines of evidence suggest that these nucleotypic correlations are influenced by body temperature, which also affects the guanine + cytosine nuclear percentage, and that they play an important role in the adaptation of these amniotes. However, the reptilian suborders exhibit differences in the quantitative and compositional characters of the genome that do not completely correspond to differences in the phenotypic parameters commonly involved in the nucleotypic effect. Thus, additional factors could have influenced genome size in this class. These data could be explained with the model of Hartl and Petrov, who observed an inverse correlation between genome size, non-coding portion of the genome and rate of DNA loss and hypothesized a strong role for different spectra of spontaneous insertions and deletions (indels) in the variations of genome size. It is thus reasonable to surmise that variations in the reptilian genome were initially influenced by different indels spectra typical of the diverse lineages, possibly related to different chromosome compartmentalizations. The consequent size increases or decreases would have influenced various morphological and functional cell parameters, and through these some phenotypic characteristics of the whole organism, especially the metabolic rate, very important for environmental adaptation and thus subject to natural selection. Through this “nucleotypic” bond, natural selection would also have controlled genome size variations.

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“…La hipótesis del origen de los microcromosomas "B" presentes en la biodiversidad mexicana, puede tener relación con la presencia de componentes xenobióticos en niveles o concentraciones elevadas (Arias-Rodriguez et al, 2007;2008;Hernández-Guzmán et al, 2011); esta idea es reforzada por los antecedentes históricos de presencia de metales pesados en sistemas acuáticos y terrestres del Golfo de México y principalmente del estado de Tabasco, de donde son procedentes las tres especies de tortugas K. leucostomum, T. scripta y S. triporcatus (Rosas et al, 1983;Villanueva & Botello, 1992;Fiedler et al, 2009;De la Cruz-Pons et al, 2012). También algunos estudios han demostrado la relevancia de los microcromosomas, por ejemplo en la tortuga Pelodiscus sinensis en la que el 50% de los genes funcionales se encuentran alojados en los microcromosomas (Kuraku et al, 2006), los cuales son ricos en secuencias de Guanina-Citosina más que en los macrocromosomas, a pesar de que los microcromosomas sólo representan el 23% del total de ADN (Olmo, Capriglione & Odierna, 2002;Olmo, 2008). La suma total de las longitudes del complemento cromosómico en K. leucostomum en mitosis (239.53±16.5µm) y en meiosis (111.99±17.8µm) está correlacionado con el contenido total de ADN diploide de 2.8 pico gramos (pg) y de 2C=2.6 pg reportados para la tortuga K. subrubrum por Olmo (1976) y De Smet (1981), respectivamente.…”

Section: Discussionunclassified