Mélany Sepúlveda Villarraga
(Tesis de Maestría – Centro Interdisciplinario de Ciencias Marinas, México)
Resumen: Se aislaron e identificaron especies de dinoflagelados asociados a macroalgas de la Bahía de La Paz. Para ello, se tomaron muestras mensuales de Sargassum horridum y Dictyota cervicornis en San Juan de la Costa e Isla Gaviota. Se establecieron cultivos monoalgales de cuatro especies de dinoflagelados, las cepas se mantuvieron en medio GSe diluido al 50%, a 24 ± 1 °C, a una salinidad de 34, en un ciclo luz: oscuridad 12h: 12h y a una intensidad luminosa de 150 μmol/m2s. Mediante características morfológicas se identificaron como Ostreopsis cf. lenticularis, Coolia malayensis, Amphidinium cf. carterae y Prorocentrum cf. rhathymum. Utilizando marcadores moleculares de la subunidad mayor de la región 28S del ADNr, se corroboró la identidad de C. malayensis. Con este marcador la cepa de Ostreopsis mostró una estrecha relación filogenética con O. lenticularis, las secuencias de los marcadores 5.8S y 18S, no coinciden con la identificación molecular de las secuencias del 28S. Sin embargo los caracteres morfológicos concuerdan con la descripción de O. lenticularis. Con el marcador 28S la cepa de Prorocentrum tuvo una estrecha afinidad filogenética con el complejo P. rhathymum/P. mexicanum, no obstante sus carácteres morfológicos corresponden a P. rhathymum. Con la cepa de Amphidinium cf. carterae se logró extraer ADN genómico, sin embargo con los cebadores utilizados para su identificación molecular no se logró la amplificación de secuencias parciales que permitieran confirmar su identidad taxonómica. Ostreopsis cf. lenticularis y Coolia malayensis no presentaron diferencias significativas en la biomasas máximas y las tasas de crecimiento al cultivarlas en medio GSe diluido y f/2. No se detectaron toxinas lipofílicas en Amphidinium cf. carterae, Ostreopsis cf. lenticularis, ni en Prorocentrum cf. rhathymum. Este trabajo contribuye a las primeras secuencias del ADN ribosomal de Ostreopsis cf. lenticularis, C. malayensis y Prorocentrum cf. rhathymum de la Bahía de La Paz.
Abstract: Different species of dinoflagellates produce toxins and can affect diverse marine organisms and public health. In Bahía de La Paz, benthic species have been associated with the production of lipophilic toxins, such as Prorocentrum lima (dinofisistoxins, ocadaic acid), Ostreopsis siamensis (palitoxins), and Gambierdiscus toxicus (ciguatoxins). In this study, dinoflagellates associated with macroalgae from the Bahía de La Paz were isolated and taxonomically identified. Samples of Sargassum horridum and Dictyota cervicornis macroalgae were collected monthly in San Juan de la Costa and Isla Gaviota. The cultures of four species of dinoflagellates were established, the strains were maintained in diluted GSe medium (50%), at 24 ± 1 ° C, salinity of 34, in a light cycle:darkness 12:12, and a irradiance of 150 μmol/m2s. Based on the morphological characteristics the strains were identified as Ostreopsis cf. lenticularis, Coolia malayensis, Amphidinium cf. carterae, and Prorocentrum cf. rhathymum. Using sequences of the long subunit of the 28S region of the ribosomal DNA we could confirm the identification of C. malayensis; and the strain of Ostreopsis presented a high phylogenetic relationship with O. lenticularis, coinciding with the morphological characteristics of the cells. Sequences of the 5.8S and 18S region of Ostreopsis did not coincide with the molecular identification of the 28S region, nevertheless the morphological characteristics coincide with O. lenticularis. The sequences of the region 28S of the strain of Prorocentrum had a close affinity with P. rathymum/mexicanum, however the morphological characteristics correspond to P. rathymum. With the strain identified morphologically as Amphidinium cf. carterae we could extract genomic ADN, but with the primers we used we could not amplify the partial sequences to confirm the taxonomic identity. Ostreopsis cf. lenticularis and C. malayensis did not present significant differences in maximum cell abundance and growth rates when cultivated in diluted GSe and f/2 media. No lipophilic toxins were detected in Amphidinium cf. carterae, Ostreopsis cf. lenticularis and Prorocentrum cf. rhathymum. This study contributes with the first ADN ribosomal sequences of Ostreopsis cf. lenticularis, C. malayensis and Prorocentrum cf. rhathymum from Bahía de La Paz.
https://repositoriodigital.ipn.mx/jspui/bitstream/123456789/26368/1/sepulvedavi1.pdf
