Erasing gametes to write blastocysts: metabolism as the new player in epigenetic reprogramming

Understanding preimplantation embryonic development is crucial for the improvement of assisted reproductive technologies and animal production. To achieve this goal, it is important to consider that gametes and embryos are highly susceptible to environmental changes. Beyond the metabolic adaptation, the dynamic status imposed during follicular growth and early embryogenesis may create marks that will guide the molecular regulation during prenatal development, and consequently impact the offspring phenotype. In this context, metaboloepigenetics has gained attention, as it investigates the crosstalk between metabolism and molecular control, i.e., how substrates generated by metabolic pathways may also act as players of epigenetic modifications. In this review, we present the main metabolic and epigenetic events of pre-implantation development, and how these systems connect to open possibilities for targeted manipulation of reproductive technologies and animal production systems.(AU)

Erasing gametes to write blastocysts: metabolism as the new player in epigenetic reprogramming

Understanding preimplantation embryonic development is crucial for the improvement of assisted reproductive technologies and animal production. To achieve this goal, it is important to consider that gametes and embryos are highly susceptible to environmental changes. Beyond the metabolic adaptation, the dynamic status imposed during follicular growth and early embryogenesis may create marks that will guide the molecular regulation during prenatal development, and consequently impact the offspring phenotype. In this context, metaboloepigenetics has gained attention, as it investigates the crosstalk between metabolism and molecular control, i.e., how substrates generated by metabolic pathways may also act as players of epigenetic modifications. In this review, we present the main metabolic and epigenetic events of pre-implantation development, and how these systems connect to open possibilities for targeted manipulation of reproductive technologies and animal production systems.

Effective individual culture system for in vitro production of bovine embryos / Sistema eficaz de cultivo individual de embriões bovinos produzidos in vitro

A new and effective protocol to culture bovine embryos without coculture and with individualized culture media has been established, which would allow the study of a single embryo's metabolism. For this purpose, bovine embryos were produced in vitro by standard protocols in three different types of media: KSOM, SOFaa, and KSOM followed by SOFaa at day 2. Presumptive zygotes were divided into six groups: control, cultured in groups (C-KSOM, C-SOFaa, and C-KS), and individual well system (W-KSOM, W-SOFaa, and W-KS). Cleavage and blastocyst rates were assessed on days 2 and 7 respectively. Relative quantification of transcripts related to important metabolic processes (GLUT1, GLUT3, GSK3, SOD1, HSPD1, G6PD) were assessed in C-KS and W-KS blastocysts. Results show that cleavage was significantly higher only in W-KSOM when compared to C-KSOM, while blastocyst rates differ only between C-SOF and W-SOF. All the other comparisons did not present statistical difference. Moreover, gene expression analysis revealed that blastocysts cultured in groups and in the individual well system present similar transcription patterns. Thus, the obtained conclusion was that the individual well system performed could be used as an effective alternative protocol for individual culture of bovine embryos, since the rates are similar to routine group culture.(AU)

Estabeleceu-se um protocolo novo e eficaz de cultivo individual de embriões bovinos sem o uso de cocultivo e sem compartilhamento de meio visando à análise do metabolismo individual do embrião. Para isso, embriões foram produzidos in vitro por protocolos convencionais em três diferentes tipos de meio: KSOM, SOFaa e KSOM seguido por SOFaa no dia 2. Os zigotos presumíveis foram divididos em seis grupos: controles (cultivo em grupo ­ C-KSOM, C-SOFaa e C-KS) e sistema de poços individuais (W-KSOM, W-SOFaa e W-KS). As taxas de clivagem foram avaliadas nos dias 2 e 7, respectivamente. Além disso, a quantificação relativa de transcritos relacionados a importantes processos metabólicos (GLUT1, GLUT3, GSK3, SOD1, HSPD1 e G6PD) foi avaliada nos blastocistos dos grupos C-KS e W-KS. Os resultados mostram que as taxas de clivagem foram maiores apenas no grupo W-KSOM quando comparado ao grupo C-KSOM, enquanto a taxa de blastocistos diferiu apenas entre os grupos C e W-SOF. Além disso, a análise da expressão gênica mostrou que blastocistos cultivados em grupo ou em sistema de poços individuais são semelhantes quanto à expressão gênica. Assim, a conclusão obtida foi que o sistema individual proposto pode ser utilizado como um protocolo alternativo eficiente para o cultivo individual de embriões de bovino, uma vez que suas características permanecem semelhantes àquelas do sistema convencional de produção de embriões.(AU)

Effective individual culture system for in vitro production of bovine embryos / Sistema eficaz de cultivo individual de embriões bovinos produzidos in vitro

A new and effective protocol to culture bovine embryos without coculture and with individualized culture media has been established, which would allow the study of a single embryo's metabolism. For this purpose, bovine embryos were produced in vitro by standard protocols in three different types of media: KSOM, SOFaa, and KSOM followed by SOFaa at day 2. Presumptive zygotes were divided into six groups: control, cultured in groups (C-KSOM, C-SOFaa, and C-KS), and individual well system (W-KSOM, W-SOFaa, and W-KS). Cleavage and blastocyst rates were assessed on days 2 and 7 respectively. Relative quantification of transcripts related to important metabolic processes (GLUT1, GLUT3, GSK3, SOD1, HSPD1, G6PD) were assessed in C-KS and W-KS blastocysts. Results show that cleavage was significantly higher only in W-KSOM when compared to C-KSOM, while blastocyst rates differ only between C-SOF and W-SOF. All the other comparisons did not present statistical difference. Moreover, gene expression analysis revealed that blastocysts cultured in groups and in the individual well system present similar transcription patterns. Thus, the obtained conclusion was that the individual well system performed could be used as an effective alternative protocol for individual culture of bovine embryos, since the rates are similar to routine group culture.(AU)

Estabeleceu-se um protocolo novo e eficaz de cultivo individual de embriões bovinos sem o uso de cocultivo e sem compartilhamento de meio visando à análise do metabolismo individual do embrião. Para isso, embriões foram produzidos in vitro por protocolos convencionais em três diferentes tipos de meio: KSOM, SOFaa e KSOM seguido por SOFaa no dia 2. Os zigotos presumíveis foram divididos em seis grupos: controles (cultivo em grupo ­ C-KSOM, C-SOFaa e C-KS) e sistema de poços individuais (W-KSOM, W-SOFaa e W-KS). As taxas de clivagem foram avaliadas nos dias 2 e 7, respectivamente. Além disso, a quantificação relativa de transcritos relacionados a importantes processos metabólicos (GLUT1, GLUT3, GSK3, SOD1, HSPD1 e G6PD) foi avaliada nos blastocistos dos grupos C-KS e W-KS. Os resultados mostram que as taxas de clivagem foram maiores apenas no grupo W-KSOM quando comparado ao grupo C-KSOM, enquanto a taxa de blastocistos diferiu apenas entre os grupos C e W-SOF. Além disso, a análise da expressão gênica mostrou que blastocistos cultivados em grupo ou em sistema de poços individuais são semelhantes quanto à expressão gênica. Assim, a conclusão obtida foi que o sistema individual proposto pode ser utilizado como um protocolo alternativo eficiente para o cultivo individual de embriões de bovino, uma vez que suas características permanecem semelhantes àquelas do sistema convencional de produção de embriões.(AU)