Expansión poblacional reciente en la historia evolutiva de la anchoveta de California Engraulis mordax

Recent population expansion in the evolutionary history of the Californian anchovy Engraulis mordax

NOE DIAZ VILORIA LAURA SANCHEZ VELASCO RICARDO PEREZ ENRIQUEZ (2012, [Artículo])

"La anchoveta de California Engraulis mordax, es una especie templada que pudo haber pasado por un proceso de disyunción poblacional, debido al proceso postglacial de calentamiento del agua alrededor de la punta de la península de Baja California, hace unos 10,000 años. Se realizó un análisis genético para probar la hipótesis nula de homogeneidad genética entre el Golfo de California, México y el sur de California, EUA y si este era el caso, estimar el tiempo de surgimiento de haplotipos en términos de coalescencia. Se analizaron en total 80 secuencias de la región control hipervariable (ADNmt) de E. mordax, capturadas en la región central del Golfo de California (n = 40) y el sur de California (n = 40). A pesar del gran número de haplotipos únicos, no se observó diferenciación genética significativa entre localidades (FST = –0.0025, p = 0.686). Una distribución unimodal en la frecuencia del número de diferencias entre haplotipos indica un modelo de expansión rápida en el tamaño poblacional, que basado en una tasa mutacional de 3.6% por millón de años para la región control, indicó un tiempo de diferenciación nucleotídica relativamente reciente de aproximadamente 61,000 años. Este periodo de tiempo corresponde al Pleistoceno tardío, después de la formación de la península de Baja California, sugiriendo expansiones poblacionales en cada una de las localidades, seguidas del último episodio de glaciación, el cual quizás contribuyó a la migración de esta especie de afinidad templada entre las dos localidades y a su homogenización genética. Sin embargo este único evento reciente de flujo genético en la historia evolutiva de la especie, no explica por sí solo los patrones de distribución encontrados en las frecuencias de diferencias nucleotídicas."

"The Californian anchovy Engraulis mordax, a temperate species, may have undergone a process of population disjunction from experiencing post-glacial water heating processes around the tip of the Baja California Peninsula, Mexico about 10,000 b.p. A genetic analysis was performed to test the null hypothesis of genetic homogeneity between the Gulf of California and Southern California, U. S. A., and if this is the case, to estimate the time of haplotype emergence in terms of coalescence. A total of 80 sequences of the mtDNA hypervariable control region of E. mordax captured in the central Gulf of California (n = 40) and Southern California (n = 40) were analyzed. In spite of the large number of private haplotypes, no significant genetic differentiation among sites (FST = –0.0025, p = 0.686) was observed. An unimodal distribution of mismatch frequency between haplotypes indicated a model of rapid expansion in population size that, based on a mutation rate of 3.6% per million years in the control region, indicates a relatively recent nucleotide differentiation

time of approximately 61,000 years. This time period corresponds to the late Pleistocene, suggesting population expansions at each locality, followed by the last episode of glaciation, which may have contributed to migration of this temperate-affinity species between two locations and the genetic homogenization. However this unique recent event of gene flow in the evolutionary history of species does not explain by itself the mismatch distribution patterns found."

ADN mitocondrial, expansión poblacional reciente, flujo genético, región control, reloj molecular. Control region, gene flow, mitochondrial DNA, molecular clock, recent population expansion. BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA ANIMAL (ZOOLOGÍA) ZOOLOGÍA MARINA ZOOLOGÍA MARINA

Estructura, dinámica y evaporación de cúmulos atómicos.

Carlos Enrique Román Velázquez (1991, [Tesis de maestría])

Se realizaron dos estudios sobre cúmulos atómicos utilizando el método de simulación de Dinámica Molecular. En el primero se desarrolló un procedimiento para el estudio y caracterización del proceso de evaporación de cúmulos atómicos. Se calcularon la tasa de evaporación y la energía cinética liberada promedio de cúmulos de varios tamaños a distintas energias. Los resultados se compararon con las predicciones de los modelos teóricos de Engelking y RRK, encontrándose una mejor descripción por parte de este último, aunque no suficientemente adecuada. En la segunda parte se realizó un estudio sistemático de la dinámica de cúmulos de átomos que interacionan mediante un potencial que involucra términos de dos y tres cuerpos diseñado para representar la interacción entre átomos de berilio. En el transcurso de este estudio se analizaron las propiedades estructurales y dinámicas de los cúmulos. Se observó un comportamiento más complejo que el manifestado por el potencial de interacción de dos cuerpos de Lennard-Jones, con frecuente aparición de fenómenos de prefusión. También se encontró una evidencia de la limitación que tiene este potencial para reproducir la dinámica de los materiales de berilio.

Dinámica molecular - Simulación por computadora, Microgrupos - Simulación por computadora, Química, física y teórica - Simulación por computadora, Mecánica cuántica CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA OTRAS ESPECIALIDADES FÍSICAS OTRAS ESPECIALIDADES FÍSICAS

Integrative taxonomy and molecular phylogeny of genus Aplysina (Demospongiae: Verongida) from Mexican Pacific

José Antonio Cruz-Barraza (2012, [Artículo])

Integrative taxonomy provides a major approximation to species delimitation based on integration of different perspectives (e.g. morphology, biochemistry and DNA sequences). The aim of this study was to assess the relationships and boundaries among Eastern Pacific Aplysina species using morphological, biochemical and molecular data. For this, a collection of sponges of the genus Aplysina from the Mexican Pacific was studied on the basis of their morphological, chemical (chitin composition), and molecular markers (mitochondrial COI and nuclear ribosomal rDNA: ITS1-5.8-ITS2). Three morphological species were identified, two of which are new to science. A. clathrata sp. nov. is a yellow to yellow-reddish or -brownish sponge, characterized by external clathrate-like morphology; A. revillagigedi sp. nov. is a lemon yellow to green, cushion-shaped sometimes lobate sponge, characterized by conspicuous oscules, which are slightly elevated and usually linearly distributed on rims; and A. gerardogreeni a known species distributed along the Mexican Pacific coast. Chitin was identified as the main structural component within skeletons of the three species using FTIR, confirming that it is shared among Verongida sponges. Morphological differences were confirmed by DNA sequences from nuclear ITS1-5.8-ITS2. Mitochondrial COI sequences showed extremely low but diagnostic variability for Aplysina revillagigedi sp. nov., thus our results corroborate that COI has limited power for DNA-barcoding of sponges and should be complemented with other markers (e.g. rDNA). Phylogenetic analyses of Aplysina sequences from the Eastern Pacific and Caribbean, resolved two allopatric and reciprocally monophyletic groups for each region. Eastern Pacific species were grouped in general accordance with the taxonomic hypothesis based on morphological characters. An identification key of Eastern Pacific Aplysina species is presented. Our results constitute one of the first approximations to integrative taxonomy, phylogeny and evolutionary biogeography of Eastern Pacific marine sponges; an approach that will significantly contribute to our better understanding of their diversity and evolutionary history. © 2012 Cruz et al.

chitin, genomic DNA, mitochondrial DNA, molecular marker, ribosome DNA, allopatry, Aplysina clatharata, Aplysina gerardogreeni, Aplysina revillagigedi, article, DNA barcoding, DNA sequence, genetic polymorphism, genetic variability, infrared spectros CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Freshwater exchanges and surface salinity in the Colombian basin, Caribbean Sea

Emilio Beier (2017, [Artículo])

Despite the heavy regional rainfall and considerable discharge of many rivers into the Colombian Basin, there have been few detailed studies about the dilution of Caribbean Surface Water and the variability of salinity in the southwestern Caribbean. An analysis of the precipitation, evaporation and runoff in relation to the climate variability demonstrates that although the salt balance in the Colombian Basin overall is in equilibrium, the area south of 12N is an important dilution sub-basin. In the southwest of the basin, in the region of the Panama-Colombia Gyre, Caribbean Sea Water is diluted by precipitation and runoff year round, while in the northeast, off La Guajira, its salinity increases from December to May by upwelling. At the interannual scale, continental runoff is related to El Niño Southern Oscillation, and precipitation and evaporation south of 12°N are related to the Caribbean Low Level Jet. During El Niño years the maximum salinification occurs in the dry season (December-February) while in La Niña years the maximum dilution (or freshening), reaching La Guajira Coastal Zone, occurs in the wet season (September-November). © 2017 Beier et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

sea water, fresh water, Article, Caribbean, dilution, dry season, El Nino, environmental parameters, evaporation, freshwater exchange, geographic distribution, molecular weight, oscillation, precipitation, river basin, salinity, seasonal variation, s CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Genetic analysis of Vibrio parahaemolyticus O3:K6 strains that have been isolated in Mexico since 1998

CARLOS ABRAHAM GUERRERO RUIZ (2017, [Artículo])

Vibrio parahaemolyticus is an important human pathogen that has been isolated worldwide from clinical cases, most of which have been associated with seafood consumption. Environmental and clinical toxigenic strains of V. parahaemolyticus that were isolated in Mexico from 1998 to 2012, including those from the only outbreak that has been reported in this country, were characterized genetically to assess the presence of the O3:K6 pandemic clone, and their genetic relationship to strains that are related to the pandemic clonal complex (CC3). Pathogenic tdh+ and tdh+/trh+ strains were analyzed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Also, the entire genome of a Mexican O3:K6 strain was sequenced. Most of the strains were tdh/ORF8-positive and corresponded to the O3:K6 serotype. By PFGE and MLST, there was very close genetic relationship between ORF8/O3:K6 strains, and very high genetic diversities from non-pandemic strains. The genetic relationship is very close among O3:K6 strains that were isolated in Mexico and sequences that were available for strains in the CC3, based on the PubMLST database. The whole-genome sequence of CICESE-170 strain had high similarity with that of the reference RIMD 2210633 strain, and harbored 7 pathogenicity islands, including the 4 that denote O3:K6 pandemic strains. These results indicate that pandemic strains that have been isolated in Mexico show very close genetic relationship among them and with those isolated worldwide. © 2017 Guerrero et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Article, bacterial strain, biofouling, controlled study, Crassostrea, food intake, gene sequence, genetic analysis, genetic variability, Japan, Mexican, Mexico, molecular phylogeny, nonhuman, pandemic, pathogenicity island, sea food, serotyping, toxi BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA GENÉTICA GENÉTICA