Abstract

CARDONA, Liliana; OLIVERA, Martha; BOTERO, Mónica  and  TARAZONA, Ariel. EFFECT OF THERMALSHOCK ON TRIPLOIDIZATION EFFICIENCY AND SURVIVAL OF LARVAE OF Rhamdia quelen. rev.udcaactual.divulg.cient. [online]. 2012, vol.15, n.2, pp.409-417. ISSN 0123-4226.

Triploidy enables improvements in fish farming since it avoids sexual maturity, controls overpopulation and increases the developmental stability. Because of its sterility, the fish harvest may be delayed, attaining fishes with greater weight and age. The aim of this study was to evaluate the effect of thermal shock on the efficiency of triploidization and the survival of Rhamdia quelen larvae. Two females and three males sexually mature were used, induced with carp pituitary extract. The eggs were inseminated and seven minutes postfertilization, submitted to thermal shock with three temperatures: 34, 36 and 38°C during two and five minutes, respectively; then incubated until hatching. Temperature, oxygen, hatching rates and survival were recorded. Larval ploidy was evaluated by staining organizing nucleolus regions (NOR) with silver nitrate. The hatching rate was similar in the control and the treatments, being of two minutes, while hatching percentage o was lower (p <0.05) in the five minutes treatments. The survival rate was higher than 91% in all treatments, without statistical difference between them. The percentages of triploidy by heat shock treatments, not including the control, ranged between 78.8 and 96.6%, without significant difference between them (p> 0.05). It was concluded that meiotic thermal shock with the three temperatures and duration within 2 to 5 minutes can induce triploid in Rhamdia quelen.

Keywords : Embryo development; meiosis; nucleolus organizer region; triploid.

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