Repositorio Nacional

Los dinoflagelados se usan como indicadores en investigaciones ecológicas y son uno de los principales causantes de toxicidad en florecimientos algales nocivos (FANs). Estas microalgas producen quistes resistentes y fosilizables, los cuales son muy útiles como indicadores bioestratigráficos y paleoecológicos. Los dinoflagelados del Cretácico han sido ampliamente estudiados en estratos de latitudes medias y altas, pero los conjuntos tropicales casi no han sido estudiados. Para ayudar a remediar esta falta de conocimiento, se estudiaron cuantitativamente y cualitativamente el contenido de dinoflagelados de 50 muestras de núcleos de los pozos ANH-CR-MONTECARLO-1X y ANH-CON-06-ST-S, localizados en Colombia. La edad de la sedimentación en ambos pozos se interpreta como Albiano, aunque hay un poco de incertidumbre en la edad de inicio. Los taxones heterotróficos tienen menor riqueza de especies, pero presentan mayor abundancia, mientras que los autótrofos tienen mayor riqueza de especies pero menor abundancia. En el pozo ANH-CR-MONTECARLO-1X se identificaron 20 géneros y 24 especies, con altos valores de concentración total de 1,441.00 qst / gr sed, en la muestra IIES-PALY-6015 por la presencia de Subtilisphaera y 1,036.88 en la muestra IIES-PALY-6021 dominada por Muderongia. Dichas muestras son correlacionables con dos transgresiones marinas, del Albiano tardío (104.4 Ma) y el Albiano temprano (111 Ma) respectivamente. Además, indican que los ensamblajes de quistes en este pozo, están dominados por formas Peridinoideas y Ceratioideas. En el pozo ANH-CON-06-ST-S se encontraron 16 géneros y 15 especies, con un valor máximo de 3,539.62 qst / gr sed en la muestra IIES-PALY-5995 por el alto contenido de Subtilisphaera, y correlacionable con la transgresión marina del Albiano tardío (104.4 Ma). Los ensamblajes de quistes en este pozo, están dominados por las formas Peridinoideas. La litología y el contenido de palinomorfos de los pozos indican un ambiente nerítico interno (NI) a transicional (T), con mayor aporte de terrígenos en el pozo ANH-CON-06-ST-S. Se propone un clima cálido para el Cretácico Inferior por la alta diversidad de taxones autótrofos característicos de aguas cálidas y estratificadas.

Dinoflagellates produce resistant and fossilizable cysts, which are useful as biostratigraphic and paleoecological indicators. These microalgae are used as indicators in ecological studies and are one of the main causes of toxicity in harmful algal blooms (HABs). Cretaceous dinoflagellates have been extensively studied in mid- and high-latitude strata, but tropical assemblages have hardly been studied. To help remedy this lack of knowledge, the dinoflagellate content of 50 core samples from the ANH-CR-MONTECARLO-1X and ANH-CON-06-ST-S wells, located in Colombia, were quantitatively and qualitatively studied. The age of sedimentation in both wells is interpreted as Albian, although there is some uncertainty in the beginning of the depositional age. Heterotrophic taxa have lower species richness but higher abundance, while autotrophs have higher species richness but lower abundance. In the ANH-CR-MONTECARLO-1X well, 20 genera and 24 species were identified, with high total concentration values of 1,441.00 cst / gr sed, in the IIES-PALY-6015 sample, due to the presence of Subtilisphaera and 1,036.88 in the IIES sample -PALY-6021, dominated by Muderongia. These samples are correlable with two marine transgressions, from the late Albian (104.4 Ma) and early Albian (111 Ma) respectively. Furthermore, they indicate that the cyst assemblages in this well are dominated by hetrotrophic forms. In the ANH-CON-06-ST-S well, 16 genera and 15 species were found, with a maximum value of 3,539.62 qst / gr sed in the IIES-PALY-5995 sample due to the high content of Subtilisphaera, and correlated with the transgression marina from the late Albian (104.4 Ma). The cyst assemblages in this well are also dominated by the heterotrophic forms. The lithology and palynomorph content of the wells indicate an internal neritic (NI) to transitional (T) environment, with a higher terrigenous influx in the ANH-CON-06-ST-S well. A warm climate is proposed for the Lower Cretaceous due to the high diversity of autotrophic taxa characteristic of warm and stratified waters.

Dinoflagelados, Cretácico Inferior, Bioestratigrafía, Paleoambientes, Paleoecología Dinoflagellates, Lower Cretaceous, Biostratigraphy, Paleoenvironment, Paleoecology CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOLOGÍA GEOLOGÍA REGIONAL GEOLOGÍA REGIONAL

Phylogenetic relationships of Pseudo-nitzschia subpacifica (Bacillariophyceae) from the Mexican Pacific, and its production of domoic acid in culture

Sonia Quijano (2020, [Artículo])

Pseudo-nitzschia is a cosmopolitan genus, some species of which can produce domoic acid (DA), a neurotoxin responsible for the Amnesic Shellfish Poisoning (ASP). In this study, we identified P. subpacifica for the first time in Todos Santos Bay and Manzanillo Bay, in the Mexican Pacific using SEM and molecular methods. Isolates from Todos Santos Bay were cultivated under conditions of phosphate sufficiency and deficiency at 16°C and 22°C to evaluate the production of DA. This toxin was detected in the particulate (DAp) and dissolved (DAd) fractions of the cultures during the exponential and stationary phases of growth of the cultures. The highest DA concentration was detected during the exponential phase grown in cells maintained in P-deficient medium at 16°C (1.14 ± 0.08 ng mL-1 DAd and 4.71 ± 1.11 × 10−5 ng cell-1 of DAp). In P-sufficient cultures DA was higher in cells maintained at 16°C (0.25 ± 0.05 ng mL-1 DAd and 9.41 ± 1.23 × 10−7 ng cell-1 of DAp) than in cells cultured at 22°C. Therefore, we confirm that P. subpacifica can produce DA, especially under P-limited conditions that could be associated with extraordinary oceanographic events such as the 2013–2016 "Blob" in the northeastern Pacific Ocean. This event altered local oceanographic conditions and possibly generated the presence of potential harmful species in areas with economic importance on the Mexican Pacific coast. © 2020 Quijano-Scheggia 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.

domoic acid, domoic acid, kainic acid, Article, cell growth, controlled study, diatom, Mexico, morphology, nonhuman, Pacific Ocean, phylogeny, plant cell, plant growth, Pseudo nitzschia, toxin analysis, cell culture technique, classification, diatom, CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Protein retention assessment of four levels of poultry by-product substitution of fishmeal in rainbow trout (Oncorhynchus mykiss) diets using stable isotopes of nitrogen (δ15N) as natural tracers

DANIEL BADILLO ZAPATA (2014, [Artículo])

This is second part from an experiment where the nitrogen retention of poultry by-product meal (PBM) compared to fishmeal (FM) was evaluated using traditional indices. Here a quantitative method using stable isotope ratios of nitrogen (δ15N values) as natural tracers of nitrogen incorporation into fish biomass is assessed. Juvenile rainbow trout (Oncorhynchus mykiss) were fed for 80 days on isotopically distinct diets in which 0, 33, 66 and 100% of FM as main protein source was replaced by PBM. The diets were isonitrogenous, isolipidic and similar in gross energy content. Fish in all treatments reached isotopic equilibrium by the end of the experiment. Two-source isotope mixing models that incorporated the isotopic composition of FM and PBM as well as that of formulated feeds, empirically derived trophic discrimination factors and the isotopic composition of fish that had reached isotopic equilibrium to the diets were used to obtain a quantitative estimate of the retention of each source of nitrogen. Fish fed the diets with 33 and 66% replacement of FM by PBM retained poultry by-product meal roughly in proportion to its level of inclusion in the diets, whereas no differences were detected in the protein efficiency ratio. Coupled with the similar biomass gain of fishes fed the different diets, our results support the inclusion of PBM as replacement for fishmeal in aquaculture feeds. A re-feeding experiment in which all fish were fed a diet of 100% FM for 28 days indicated isotopic turnover occurred very fast, providing further support for the potential of isotopic ratios as tracers of the retention of specific protein sources into fish tissues. Stable isotope analysis is a useful tool for studies that seek to obtain quantitative estimates of the retention of different protein sources. © 2014 Badillo et al.

nitrogen 15, nitrogen, protein intake, animal behavior, animal experiment, animal food, animal tissue, aquaculture, Article, biomass, controlled study, energy metabolism, food composition, juvenile animal, nonhuman, poultry by product meal, protein a CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA