Tetraploidia em Rhamdia quelen (Quoy e Gaimard, 1824) por choque térmico duplo (quente e frio)

Abstract

The efficiency of double thermal shock to induce tetraploidy in Rhamdia quelen (jundiá) at different post-fertilization periods was assessed. Each test was performed with 20 mL of eggs (10, 15, 20, 25, 30 and 35 mpf -minutes post-fertilization) exposed to hot thermal shock (39±0.2ºC) for 3 min, followed by cold thermal shock (1.0±0.1ºC) for 30 min. A control group was also employed. Fertilization and hatching rates were evaluated 12 and 30 hours post-fertilization (hpf), respectively. After 60 hpf, twenty-five larvae from each experimental unit were fixed to verify the ploidy by flow cytometry. Control fertilization rate was 87.83% and reached 23. 4%, 28.5%, 30.4%, 20.0%, 30.3%, 36.7% respectively for 10, 15, 20, 25, 30, 35 mpf. Tetraploids were detected only at 15 mpf and 20 mpf. This is the first research of tetraploidy in jundiá obtained by hot and cold shocks, making possible the improvement of this technique.Key words: jundiá; tetraploidy; thermal shock; poliploidy.. RESUMOAvaliou-se a eficiência do choque térmico duplo para induzir tetraploidia em jundiá Rhamdia quelen em diferentes tempos pós-fertilização. Vinte mililitros de ovos (10, 15, 20, 25, 30 e 35 mpf -minutos pós-fertilização) foram tratados com choque térmico quente (39±0,2ºC) durante 3 min seguido de choque térmico frio (1,0±0,1ºC) durante 30 min. Um grupo controle foi utilizado. As taxas de fertilização e de eclosão foram medidas 12 hpf (horas pós-fertilização) e 30 hpf, respectivamente. Decorridas 60 hpf, 25 larvas de cada unidade experimental foram fixadas para verificação da ploidia, por citometria de fluxo. A taxas de fertilização foram de 87,83% para o controle e de 23,4%; 28,5%; 30,4%; 20,0%; 30,3% e 36,7%, para os grupos tratados com choque térmico aos 10, 15, 20, 25, 30, 35 mpf, respectivamente. Encontraram-se tetraploides apenas nos grupos de ovos tratados aos 15 mpf e 20 mpf. Este é o primeiro trabalho de indução de tetraploidia em jundiá por choques térmicos quente e frio, o qual possibilitou o aperfeiçoamento dessa técnica.Palavras-chave: jundiá; tetraploide; choque de temperatura; poliploidia.

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

“…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.…”

“…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 ).…”

Opportunities and challenges for fish culture in Brazilian reservoirs: a review

“…Another option to minimize the risks arising from accidental escapes is the cultivation of monosex lines, using the traditional method for the application of sex hormones, the tetraploidy technique (Garcia et al, 2017), or the production of neomales (Weiss et al, 2017). An additional advantage of monosex cultivation is that several species of fish have different growth potentials between males and females, allowing the fish farmer to exclusively cultivate the genus with greater zootechnical advantage or market value.…”

Return temperature after heat shock affects the production of tetraploids in the yellowtail tetra Astyanax altiparanae

“…However, protocols for tetraploid induction are difficult to establish, limited to a few species and generally result in low survival (Yoshikawa et al, 2008;Piferrer et al, 2009). In the Neotropical region, studies on the production of tetraploid fish have been restricted to only two species, the silver catfish Rhamdia quelen (Garcia et al, 2018) and the yellowtail tetra Astyanax altiparanae (do Nascimento et al, 2020b).…”