Sara Islas

Centro de Estudios Gnealógicos, para la investigación de la cultura en México y América Latina, A. C., Tecnociencias, Alumna

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Address: Tijuana, Baja California, Mexico

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Orlando CORREA LUNA

Amparo Latorre

Universitat de València

Achim Kempf

Ruben Valas

Charles Lineweaver

The Australian National University

Bastien Boussau

Centre National de la Recherche Scientifique / French National Centre for Scientific Research

David Mead

Pedro Jordano

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)

L Aravind

National Institutes of Health

David Penny

Massey University

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Papers by Sara Islas

The Very Early Stages of Biological Evolution and the Nature of the Last Common Ancestor of the Three Major Cell Domains

Annual Review of Ecology Evolution and Systematics, 2007

Quantitative estimates of the gene complement of the last common ancestor of all extant organisms... more Quantitative estimates of the gene complement of the last common ancestor of all extant organisms, that is, the cenancestor, may be hindered by ancient horizontal gene transfer events and polyphyletic gene losses, as well as by biases in genome databases and methodological artifacts. Nevertheless, most reports agree that the last common ancestor resembled extant prokaryotes. A significant number of the highly conserved genes are sequences involved in the synthesis, degradation, and binding of RNA, including transcription and translation. Although the gene complement of the cenancestor includes sequences that may have originated in different epochs, the extraordinary conservation of RNA-related sequences supports the hypothesis that the last common ancestor was an evolutionary outcome of the so-called RNA/protein world. The available evidence suggests that the cenancestor was not a hyperthermophile, but it is currently not possible to assess its ecological niche or its mode of energy acquisition and carbon sources. 361 Annu. Rev. Ecol. Evol. Syst. 2007.38:361-379. Downloaded from arjournals.annualreviews.org by HARVARD UNIVERSITY on 08/30/09. For personal use only. LCA: last common ancestor RNA world: an evolutionary stage prior to proteins and DNA genomes during which life was based on catalytic and replicative RNAs 362 Becerra et al.

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Question 7: Comparative Genomics and Early Cell Evolution: A Cautionary Methodological Note

Origins of Life and Evolution of Biospheres, 2007

Inventories of the gene content of the last common ancestor (LCA), i.e., the cenancestor, include... more Inventories of the gene content of the last common ancestor (LCA), i.e., the cenancestor, include sequences that may have undergone horizontal transfer events, as well as sequences that have originated in different pre-cenancestral epochs. However, the universal distribution of highly conserved genes involved in RNA metabolism provide insights into early stages of cell evolution during which RNA played a much more conspicuous biological role, and is consistent with the hypothesis that extant living systems were preceded by an RNA/protein world. Insights into the traits of primitive entities from which the LCA evolved may be derived from the analysis of paralogous gene families, including those formed by sequences that resulted from internal elongation events. Three major types of paralogous gene families can be recognized. The importance of this grouping for understanding the traits of early cells is discussed.

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Hyperthermophily and the origin and earliest evolution of life

International Microbiology, 2003

The possibility of a high-temperature origin of life has gained support based on indirect evidenc... more The possibility of a high-temperature origin of life has gained support based on indirect evidence of a hot, early Earth and on the basal position of hyperthermophilic organisms in rRNA-based phylogenies. However, although the availability of more than 80 completely sequenced cellular genomes has led to the identification of hyperthermophilic-specific traits, such as a trend towards smaller genomes, reduced protein-encoding gene sizes, and glutamic-acid-rich simple sequences, none of these characteristics are in themselves an indication of primitiveness. There is no geological evidence for the physical setting in which life arose, but current models suggest that the Earth's surface cooled down rapidly. Moreover, at 100 °C the half-lives of several organic compounds, including ribose, nucleobases, and amino acids, which are generally thought to have been essential for the emergence of the first living systems, are too short to allow for their accumulation in the prebiotic environment. Accordingly, if hyperthermophily is not truly primordial, then heat-loving lifestyles may be relics of a secondary adaptation that evolved after the origin of life, and before or soon after separation of the major lineages.

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Polyphyletic gene losses can bias backtrack characterizations of the cenancestor

Journal of Molecular Evolution, 1997

... JL, Nguyen D, Utterback TR, Kelley JM, Peterson JD, Sadow PW, Hanna MC, Cotton MD, Roberts KM... more

Rubricas Edicion Especial profesores

La Rúbricas pretende mostrar las ideas y alcances académicos/as de la comunidad universitaria, a ... more La Rúbricas pretende mostrar las ideas y alcances académicos/as de la comunidad universitaria, a fin de obtener una necesaria retroalimentación. La perspectiva es plural, como plurales son las comunidades universitarias, pero con la idea de generar, propiciar, circular pensamiento propio, desde nuestros propios intereses y apuestas.

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The Very Early Stages of Biological Evolution and the Nature of the Last Common Ancestor of the Three Major Cell Domains

Annual Review of Ecology Evolution and Systematics, 2007

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Question 7: Comparative Genomics and Early Cell Evolution: A Cautionary Methodological Note

Origins of Life and Evolution of Biospheres, 2007

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Hyperthermophily and the origin and earliest evolution of life

International Microbiology, 2003

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Polyphyletic gene losses can bias backtrack characterizations of the cenancestor

Journal of Molecular Evolution, 1997