Heat-induced triploids in Brycon amazonicus: a strategic fish species for aquaculture and conservation

Abstract

Summary Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.

Establishing a model fish for the Neotropical region: The case of the yellowtail tetra Astyanax altiparanae in advanced biotechnology

“…However, some techniques developed for the yellowtail tetra may be promptly used in other species. For instance, triploidization of Brycon amazonicus ( Nascimento et al, 2021 ) and Prochilodus lineatus ( Yasui et al, 2020b ) was successful when using the same procedures of heat shocking for second polar body retention (2 mpf for 2 min, 40°C). In addition, confirmation of the ploidy status using flow cytometry was achieved using the protocol established for yellowtail tetra ( Xavier et al, 2017 ; Yasui et al, 2020a ).…”

“…Based on the results obtained for yellowtail tetra, several advances within other Neotropical species were established. Using the same temperature (40°C) to induce triploids in the yellowtail tetra, triploid progenies were obtained for the streaked prochilod Prochilodus lineatus ( Yasui et al, 2020b ) and Brycon amazonicus ( Nascimento et al, 2021 ). With some minor modifications, triploids and tetraploids were also generated when the temperature was set at 38°C for Pimelodus maculatus ( Bertolini et al, 2020 ) and Rhamdia quelen ( Garcia et al, 2017 ; García et al, 2017 ).…”

“…B. amazonicus ( Da Silva et al, 2017 ), Pimelodus maculatus and Pseudopimelodus mangurus ( Arashiro et al, 2018 ), and P. lineatus ( Coelho et al, 2019 ) were also studied in the field of embryology using the same procedures and temperatures (22°C, 26°C, and 30°C) as used for the yellowtail tetra. The same protocol for cytometric analysis established in the yellowtail tetra ( Xavier et al, 2017 ) was used to identify polyploids in B. amazonicus ( Nascimento et al, 2021 ), P. lineatus ( Yasui et al, 2020b ), P. maculatus ( Bertolini et al, 2020 ), and R. quelen ( Garcia et al, 2017 ).…”

Manual vs. automated erythrocyte assessment for polyploidy detection in neotropical fish: a comparative study

“…Consequently, automatic measurements are an interesting alternative to optimize this process. Therefore, the aim of this study was to evaluate two distinct methodologies -manual and automated -for characterizing erythrocytes among diploid and triploid specimens from four economically significant Neotropical fish species: Astyanax altiparanae (Garutti & Britski, 2000) Triploid fishes were induced in accordance with our previously established protocols (Adamov et al, 2017;Bertolini et al, 2020;Nascimento et al, 2021;Yasui et al, 2020). We used 10 diploids and 10 triploids and of Astyanax altiparanae (8 months of age), 6 diploids and 11 triploids of Prochilodus lineatus (2 years), 12 diploids and 3 triploids of Brycon amazonicus (2 years), and 6 diploids and 3 triploids of Pimelodus maculatus (1 year).…”