Browsing by Author "Del Pino Veintimilla, Eugenia"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Open Access 
Analysis of cell size in the gastrula of ten frog species reveals a correlation of egg with cell sizes, and a conserved pattern of small cells in the marginal zone(2016-07-10) Del Pino Veintimilla, Eugenia; Vargas, Alexandra; Del Pino Veintimilla, EugeniaWe investigated the relationship between egg and cell sizes in the early gastrula of ten species of frogs with eggs of 1,100-3,500 μm diameters. We asked whether differences in cell size of the vegetal region, blastocoel roof, and marginal zone of the early gastrula were associated with egg size. Alternatively, we proposed that cell size differences may associate with gastrulation characteristics. The analyzed species were as follows: Xenopus laevis, Engystomops randi, Engystomops coloradorum, Espadarana callistomma, Epipedobates machalilla, Epipedobates anthonyi, Epipedobates tricolor, Dendrobates auratus, Gastrotheca riobambae, and Eleutherodactylus coqui. A positive correlation between egg and cell size was detected in the three regions of the gastrula. The correlation was strong in the vegetal region and blastocoel roof, and weak in the marginal zone. Large eggs allowed the evolution of frog terrestrial reproductive modes by storing nourishment for the developing embryos. Large cells, laden with yolk, occur in the vegetal region. However, small cell size characterized the marginal zone and blastocoel roof. We proposed that small cells of the marginal zone are required for involution and blastopore formation. The evolution pressure toward small cells in the marginal zone contributed to maintain the blastopore as a universal feature of frog gastrulation in eggs of different sizes and gastrulation modes. Our comparative analysis revealed two fundamental and conserved properties of the frog early gastrula, the correlation of egg with cell sizes, and the general small size of cells in the marginal zone.Item Open Access Desarrollo temprano de Hyalinobatrachium fleischmanni y Espadarana callistomma (Anura: Centrolenidae) desde el clivaje hasta la eclosión del renacuajo.(PUCE - Quito, 2013) Salazar Nicholls, María José; Del Pino Veintimilla, EugeniaEl presente estudio describe y analiza el desarrollo embrionario, desde el clivaje hasta la eclosión de los renacuajos en dos ranas de la familia Centrolenidae, Hyalinobatrachium fleischmanni y Espadarana callistomma. Estas ranas se caracterizan por depositar sus huevos (2,1 mm de diámetro) en masas gelatinosas en hojas sobre corrientes de agua. Las especies presentan diferencias en la pigmentación del huevo. Los huevos de H. fleischmanni son blancos y son depositados en el envés de las hojas donde no están expuestos a la radiación UV, mientras que los huevos de Espadarana callistomma tienen una pigmentación marrón en el hemisferio animal y son depositados en el haz de las hojas donde están expuestos a la radiación UV.Item Open Access Development and gastrulation in Hyloxalus vertebralis and Dendrobates auratus (Anura: Dendrobatidae).(2015-03-22) Del Pino Veintimilla, Eugenia; Del Pino Veintimilla, EugeniaWe document the embryonic development of Hyloxalus vertebralis, a frog species of the Ecuadorian highlands, declared as Critically Endangered by the International Union for the Conservation of Nature (IUCN) due to significant declines in its populations. Our work may be of value for conservation and management of this endangered frog, especially as it is being bred in captivity to ensure against extinction. We were able to analyze and compare the development of H. vertebralis with Dendrobates auratus (Dendrobatidae), and other frogs, because of the successful reproduction in captivity of Ecuadorian frogs at the Balsa de los Sapos, Centre of Amphibian Investigation and Conservation (CICA), of the Pontificia Universidad Católica del Ecuador, in Quito. Embryos were fixed, and the external and internal morphology was described from whole mounts, and serial sections. Cellular morphology was analyzed by staining nuclei. Embryos of H. vertebralis and D. auratus developed from eggs that were 2.6 and 3.5 mm in diameter, respectively. In spite of the large size of their eggs, the morphology of H. vertebralis embryos from cleavage to hatching was similar to the morphology of Epipedobates machalilla (Dendrobatidae) embryos. The comparison of gastrulation morphology was extended to six additional species of Dendrobatidae (E. machalilla, Epipedobates anthonyi, Epipedobates tricolor, H. vertebralis, Ameerega bilinguis, D. auratus), and to Xenopus laevis (Pipidae), and Gastrotheca riobambae (Hemiphractidae). We found that elongation of the notochord occurs after blastopore closure in the six species of dendrobatid frogs, as in G. riobambae; whereas gastrulation and notochord elongation overlap during X. laevis development. We propose that the separation of gastrulation from notochord elongation may relate to slower development patterns, probably associated with the terrestrial reproductive strategies of dendrobatid frogs and marsupial frogs. This analysis contributes to the knowledge of frog embryology and gastrulation, and provides developmental information that may be useful for the conservation and management of H. vertebralis.Item Open Access Developmental diversity of amphibians.(2012) Del Pino Veintimilla, Eugenia; Elinson, Richard P.The current model amphibian, Xenopus laevis, develops rapidly in water to a tadpole which metamorphoses into a frog. Many amphibians deviate from the X. Laevis developmental pattern. Among other adaptations, their embryos develop in foam nests on land or in pouches on their mother´s back or on a leaf guarded by a parent. The diversity of developmental patterns includes multinucleated oogenesis, lack of RNA localization, huge non-pigmented eggs, and asynchronous, irregular early cleavages. Variations in patterns of gastrulation highlight the modularity of this critical developmental period. Many species have eliminated the larva or tadpole and directly develop to the adult. the wealth of developmental diversity among amphibiand coupled with the wealth of mechanistic information from X. laevis permit comparisons that provide deeper insights into developmental processes.Item Open Access Expresión de la proteína vegt en embriones tempranos de las ranas Engystomops randi y Epipedobates machalilla en comparación con Xenopus laevis(PUCE - Quito, 2012) Garcés Vásconez, Andrés Gonzalo; Del Pino Veintimilla, EugeniaSe estudió la expresión de la proteína vegt por inmuno-detección en montaje entero, en embriones de Engystomops randi (Leiuperidae) y Epipedobates machalilla (Dendrobatidae) en los estadios de clivaje tardío, blástula y gástrula en comparación con Xenopus laevis. Los objetivos fueron probar si el anticuerpo policlonal en contra de la proteína vegt de X. laevis (producido por el Dr. M. Taira y colaboradores, Universidad de Tokio, Japón) da reacción cruzada con embriones de otras especies para identificar a nivel molecular la localización del endodermo y endomesodermo presuntivo en embriones de diferentes ranas. La expresión de la isoforma materna de vegt se detectó en el estadio de clivaje tardío y blástula, y hubo diferencias entre E. randi y E. machalilla. En E. randi la isoforma materna de vegt se localizó en una amplia zona marginal y región vegetal del clivaje tardío y blástula, mientras que en E. machalilla se localizó principalmente en la zona marginal en ambos estadios. Se considera que las regiones positivas para vegt corresponden al endodermo y endomesodermo de E. randi y E. machalilla. Se sugiere que la diferencia en el patrón de expresión de vegt esta asociada al tamaño del huevo y velocidad de desarrollo. En la gástrula no se detectó a la isoforma zigótica de la proteína vegt en ninguna de las especies analizadas. Esta isoforma posiblemente tiene diferente estructura tridimensional en relación a la isoforma materna, o el sitio de reconocimiento del antígeno en la proteína podría estar enmascarado, dificultando la detección de la proteína zigótica de vegt. Estos resultados sugieren que la proteína vegt detectada por el anticuerpo corresponde a la isoforma materna de vegt.Item Open Access The gastrocoel roof plate in embryos of different frogs.(2012) Del Pino Veintimilla, Eugenia; Del Pino Veintimilla, EugeniaThe morphology of the gastrocoel roof plate and the presence of cilia in this structure were examined in embryos of four species of frogs. Embryos of Ceratophrys stolzmani (Ceratophryidae) and Engystomops randi (Leiuperidae) develop rapidly, provide comparison for the analysis of gastrocoel roof plate development in the slow-developing embryos of Epipedobates machalilla (Dendrobatidae) and Gastrotheca riobambae (Hemiphractidae). Embryos of the analyzed frogs develop from eggs of different sizes, and display different reproductive and developmental strategies. In particular, dorsal convergence and extension and archenteron elongation begin during gastrulation in embryos of rapidly developing frogs, as in Xenopus laevis. In contrast, cells tahta involute during gastrulation are stored in the large circumblastoporal collar that develops around the closed blastopore in embryos of slow-developing frogs. Dorsal convergence and extension only star after blastopore closuer in slow-dveloping frog embryos. However, in the neurulate, a gastrocoel roof plate develops, despite the accumulation of superficial mesodermal cells in the circumblastoporal collar. Embryos of all four species develop a ciliated gastrocoel roof plate at the beginning of neurulation. Accordingly, fluid-flow across the gastrocoel roof plate is likely the mechanism of left-right asymmetry patterning in these frogs, as in X. laevis and other vertebrates. A ciliated gastrocoel roof plate, with a likely origin as superficial mesoderm, is conserved in frogs belonging to four different families and with different modes of gastrulation.Item Open Access Morfología de los embriones desde la blástula hasta la eclosión del renacuajo de dos especies de Atelopus (Anura: Bufonidae)(PUCE - Quito, 2013) Jiménez Merino, Juan; Del Pino Veintimilla, EugeniaLas especies del género Atelopus se encuentran amenazadas, por lo que es importante realizar estudios sobre su biología. Se describen y se analizan los patrones morfológicos del desarrollo embrionario, desde el estadio de blátula hasta la eclosión de los renacuajos, de dos especies de ranas ecuatorianas: Atelopus sp. y Atelopus elegans (Anura: Bufonidae). Estas ranas poseen un modo reproductivo acuático, y realizan sus posturas en agua corriente. La morfología de los embriones fue analizada mediante montajes enteros y secciones de vibrátomo. Adicionalmente, se realizaron tinciones de fluorescencia para núcleos celulares.Item Open Access Morfología, estructura interna y somitogénesis de los embriones de Hyloxalus vertebralis y Dendrobates auratus (Anura: Dendrobatidae) desde la néurula hasta la eclosión del renacuajo(PUCE - Quito, 2012) Hervas Sotomayor, Francisca; Del Pino Veintimilla, EugeniaEn el presente estudio se describe la estructura de los embriones desde la néurula hasta la eclosión del renacuajo, de dos especies de ranas de la familia Dendrobatidae: Hyloxalus vertebralis y Dendrobates auratus. Estas especies difieren en su tamaño de huevo. Además, se analiza la morfología de los somitas y la expresión de proteínas musculares de las miofibrillas, mediante la inmunodetección con el anticuerpo muscular 12/101.Item Open Access La placa del techo del gastrocele de Epipedobates tricolor (Anura: Dendrobatidae).(2012) Del Pino Veintimilla, Eugenia; Del Pino Veintimilla, EugeniaEn la mayoría de los vertebrados usados como modelo del desarrollo, la determinación de la asimetría izquierda-derecha de la localización de órganos tales como el corazón se determina en la neurula y obedece a un flujo de fluido hacia el lado izquierdo. El flujo de fluido está guiado por el movimiento sincronizado de cilios en el techo del gastrocele, que corresponde a la cara interna del techo de la neurula de los anuros. Se estudió la morfología de la neurula y la placa del techo del gastrocele del anuro ecuatoriano, Epipedobates tricolor (Dendrobatidae). La placa del techo del gastrocele de la neurula de E. tricolor reviste dorsalmente a la cavidad del gastrocele y consiste de un epitelio monociliado, como en Xenopus laevis y otras ranas. La longitud de los cilios de E. tricolor fue de 8 µm en promedio. La placa del techo del gastrocele de E. tricolor comparte las características morfológicas observadas en la rana dendrobátida, Epipedobates machalilla y otras ranas con diversos modos reproductivos. La comparación sugiere que E. tricolor mantiene el mecanismo de flujo de fluido guiado por cilios para la determinación de la asimetría izquierda-derecha, como en otros anuros.Item Open Access Variation in the schedules of somite and neural development in frogs.(2012) Del Pino Veintimilla, Eugenia; Sáenz Ponce, NataliaThe timing of notochrod, somite, and neural development was analyzed in the embryos of six differnt frog species, which have been divided into two groups, according to their developmental speed. Rapid developing species investigated were Xenopus laevis (Pipidae), Engystomops coloradorum, and Engystomops randi (Leiuperidae). the slow developers were Epipedobates machalilla and Epipedobates tricolor (Dendrobatidae) and Gastrotheca riobambae (Hemiphractidae). Blastopore closure, notochord formation, somite development, neural tube closure, and the formation of cranial neural crest cell-streams were detected by light and scanning electron microscopy and by immuno-hisochemical detection of somite and neural crest marker proteins. The data were analyzed using event pairing to determine common developmental aspects and their relationship to life-history traits. In embryos of rapidly developing frogs, elongation of the notochord occured earlier relative to the time point of blastopore closure in comparison with slowly developing species. The development of cranial neural crest cell-streams relative to somite formation is accelerated in rapidly developing frogs, and it is delayed in slowly developing frogs. The timing of neural tube closure seemed to be temporally uncoupled with somite formation. We propose that these changes are achieved through differential timing of developmental modules that begin with the elongation of the notochord during gastrulation in the rapidly developing species. The differences might be related to the necessity of developing a free-living tadpole quickly in rapid devleopers.