Relacion ARN/ADN como indice de condicion fisiologica del hibrido de la cachama Colossoma macropomum y el morocoto piaractus brachypomus durante el desarrollo embrionario / RNA/DNA ratio as an index of physiological condition of Colossoma macropomum and Piaractus branchypomus (Pisces: Characiformes) during embryonic development

RESUMO

We evaluated RNA/DNA ratio as an index of physiological condition during larval development of a hybrid between the fishes Colossoma macropomum (cachama) and Piaractus brachypomus (morocoto). The samples were obtained by induced reproductive technology and the eggs were maintained in acrylic conical incubator with a continuous waterflow. Embryonic development, from egg fertilization to cell division and hatch out, took 12 hours 20 minutes at 29.5 degrees C, dissolved oxygen contents of 6.0 ppm and pH 7.5. Nucleic acids quantification was determined by fluorometry with ethidium bromide and Hoechst 33258 dyes. We observed significant changes of RNA/DNA ratios during all stages of the embryonic larval development. Therefore, RNA/DNA relation is an useful technique to evaluate physiological condition in short period and could be utilized as nutritional condition and/or instantaneous growth for routine check to verify the health status in early life of cultivated species