Crescimento e aspectos reprodutivos do pimelodus maculatus triploides
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Data
2018-02-26
Autores
Bertolini, Rafaela Manchin
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Universidade Estadual Paulista (Unesp)
Resumo
A triploidização é uma ferramenta interessante para produzir peixes estéreis. No Mandi amarelo, Pimelodus maculatus isso pode ser aplicada como uma ferramenta de reconstituição de espécies ameaçadas através de transplante de células germinativastronco. No capítulo I, objetivou-se estabelecer um protocolo eficiente para a triploidização da espécie P. maculatus empregando choques de térmicos. As temperaturas testadas foram de 37°C, 38°C e 39°C, 2 minutos pós-fertilização durante 2 minutos. Os embriões intactos serviram como grupo controle diplóide. A ploidia foi confirmada por citometria de fluxo, diâmetro nuclear dos eritrócitos e citogenética. Taxas de fertilização e sobrevivência foram verificadas nos principais estágios de desenvolvimento embrionário (clivagem, blástula, gástrula, segmentação e eclosão), assim como a porcentagem de larvas normais e anormais, e eficiência da triploidização. O choque térmico reduziu significativamente a sobrevivência no estágio de gástrula (P = 0,0178), somito (P = 0,0469) e incrementou o porcentual de larvas anormais (P = 0,0261). A menor sobrevivência foi observada para o tratamento a 39°C. Todos os tratamentos apresentaram altas porcentagens de indivíduos triploides, sendo o maior valor observado para o choque a 38°C (96,7%). Com base nos resultados acima, foi obtido um eficiente protocolo de triploidização em P. maculatus utilizado choque quente (38°C, 2 mpf e duração de 2 minutos). No capitulo II, foram avaliados aspectos relacionados ao desempenho reprodutivo e crescimento de indivíduos diploides (2n) e triploides (3n) da espécie P. maculatus. O objetivo foi avaliar crescimento entre as duas diferentes ploidias através do peso, comprimento, rendimento de carcaça, índice gonodassomatico e a possível esterilidade em peixes triploides por meio de análise histológica. Fêmeas 2n apresentaram valores de IGS significativamente maiores (P= 0,0157). A análise histológica mostrou fêmeas 2n em fase de maturação. Por outro lado, gônadas de fêmeas 3n apresentaram somente oogônias, células apoptóticas e poucos oócitos primários isolados. Machos 2n apresentaram gametogênese normal, ao passo que em machos 3n não foram observados esprmatozoides formados. Portanto, não foram observados gametas em fêmeas e machos 3n de P. maculatus, sendo considerados estéreis. Essas características são aplicáveis tanto nas ciências básicas, como modelo experimental, bem como nas ciências aplicadas, para a produção em larga escala.
Triploidization is an interesting tool to produce sterile fish. In the spotted catfish Pimelodus maculatus, this may be used as a tool for reconstitution of endangered species based on stem germ cell transplantation. In Chapter I, the study aimed to establish an efficient protocol for triploidization in the spotted catfish P. maculatus using temperature shock. The temperatures tested were 37°C, 38°C e 39°C, 2 min postfertilization during 2 minutes. Intact embryos served as diploid control. Ploidy status was confirmed by flow cytometry, nuclear diameter of erythrocytes and karyotyping. Fertilization and hatching rates were verified at the main embryo stages (cleavage, blastula, gastrula, somite stage and hatching), the percentage of normal and abnormal larvae and also the efficacy of triploidization. Heat shock decrease the survival at blastula stage (P= 0,0178), somite (P = 0,0469) and increased the percentage of abnormal larvae (P = 0,0261). The lowest survival was observed at 39 °C. All treatments presented high percentages of triploid individuals, and the highest values were observed for heat shock at 38°C (96,7%). Based on results above, it was obtained an efficient protocol for triploidization in P. maculatus using heat shock (38°C, 2 min postfertilization during 2 minutes). In Chapter II, aspects related to the growth and reproductive performance of diploid (2n) and triploid (3n) of P. maculatus were evaluated. The objective was to evaluate growth according with the ploidy status, through length, weight, carcass yield, gonadassometic index and possible sterility in triploid fish by means of histological analysis. Diploid females presented significantly higher IGS values (P = 0.0157). Histological analysis showed 2n females in maturation stage. On the other hand, gonads of 3n-females presented only oogonia, apoptotic cells and few isolated primary oocytes. Diploid males presented normal gametogenesis, although in 3n-males spermatozoa were not observed. However, gametes were not observed in females and males 3n of P. maculatus, considered then as sterile sterile.
Triploidization is an interesting tool to produce sterile fish. In the spotted catfish Pimelodus maculatus, this may be used as a tool for reconstitution of endangered species based on stem germ cell transplantation. In Chapter I, the study aimed to establish an efficient protocol for triploidization in the spotted catfish P. maculatus using temperature shock. The temperatures tested were 37°C, 38°C e 39°C, 2 min postfertilization during 2 minutes. Intact embryos served as diploid control. Ploidy status was confirmed by flow cytometry, nuclear diameter of erythrocytes and karyotyping. Fertilization and hatching rates were verified at the main embryo stages (cleavage, blastula, gastrula, somite stage and hatching), the percentage of normal and abnormal larvae and also the efficacy of triploidization. Heat shock decrease the survival at blastula stage (P= 0,0178), somite (P = 0,0469) and increased the percentage of abnormal larvae (P = 0,0261). The lowest survival was observed at 39 °C. All treatments presented high percentages of triploid individuals, and the highest values were observed for heat shock at 38°C (96,7%). Based on results above, it was obtained an efficient protocol for triploidization in P. maculatus using heat shock (38°C, 2 min postfertilization during 2 minutes). In Chapter II, aspects related to the growth and reproductive performance of diploid (2n) and triploid (3n) of P. maculatus were evaluated. The objective was to evaluate growth according with the ploidy status, through length, weight, carcass yield, gonadassometic index and possible sterility in triploid fish by means of histological analysis. Diploid females presented significantly higher IGS values (P = 0.0157). Histological analysis showed 2n females in maturation stage. On the other hand, gonads of 3n-females presented only oogonia, apoptotic cells and few isolated primary oocytes. Diploid males presented normal gametogenesis, although in 3n-males spermatozoa were not observed. However, gametes were not observed in females and males 3n of P. maculatus, considered then as sterile sterile.
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Palavras-chave
Mandi amarelo, Triploidização, Manipulação cromossômica, Esterilização, Spotted catfish, Triploidization, Chromosome manipulation, Sterilization