Cumulus-oocyte complexes from sows show differences in lipid metabolism compared to cumulus-oocyte complexes from prepubertal gilts during in vitro maturation.

This study aimed to evaluate the effects of donor age on lipid metabolism during in vitro maturation (IVM) of pigs cumulus-oocyte complexes (COCs). We evaluated transcript levels of genes, the percentage of ooplasm occupied by lipid droplets (LD) and evaluated DNA methylation in COCs from sows and prepubertal gilts. Transcript levels of six genes (ACACA, ACSS2, FASN, FABP3, SLC27A4, PLIN2), which were analyzed in cumulus cells (CCs), increased after 44 h of IVM in the sow group. In the gilt group, only FASN expression increased, while NR3C1 expression decreased after IVM. The measurement of LD in oocytes showed an accumulation of lipids in sow oocytes during IVM, while gilt oocytes showed a decrease in LD. FABP3 and NR3C1 methylation patterns exhibited a demethylation pattern in CCs and oocytes from gilts and sows and showed statistical differences between groups. CCs from sows had a better capacity to change transcription levels of the major genes involved in lipid metabolism during IVM than CCs from gilts. This difference may be involved in accumulation of lipids, acquisition of competence, and maturation of enclosed oocytes. Our results contribute to a better understanding of mechanisms involved in lipid metabolism and acquisition of competence in porcine COCs.

Distribution of 5-methylcytosine and 5-hydroxymethylcytosine in bovine fetal tissue of the placenta / Distribuição de 5-metilcitosina e 5-hidroximetilcitosina em placenta fetal bovina

5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) are modified cytosines found in mammals that are involved in the regulation of gene expression. The aim of this study was to characterize the global patterns of 5-mC and 5-hmC of the fetal placenta of Nellore cattle as well as blood and sperm as controls. 5-mC and 5-hmC levels were determined using MethylFlash Methylated/Hydroxymethylated DNA Quantification Kit, respectively. Placenta tissues showed lower levels of 5-mC and 5-hmC compared to sperm. The male cotyledon showed higher levels of 5-hmC than the female. For the first time, the levels of 5-mC and 5-hmC in Bos taurus indicus were characterized, which may contribute to our understanding of the mechanisms of epigenetic regulation in the placenta. The presence of 5-hmC in somatic tissues suggest that 5-hmC has its own biological function and it is not only a byproduct from the oxidation of 5-mC. These results may be of interest in ARTs, especially in cloning in the diagnosis/prognosis of aberrant placentation and the viability of pregnancies.(AU)

5-metilcitosina (5-mC) e 5-hidroximetilcitosina (5-hmC) são citosinas modificadas encontradas nos mamíferos que estão envolvidas com a regulação da expressão gênica. O objetivo do presente estudo foi caracterizar os padrões globais de 5-mC e 5-hmC em placenta fetal de animais da raça Nelore, assim como em sangue e espermatozoides, usados como controles. Os níveis de 5-mC e 5-hmC foram determinados usando os kits MethylFlash Methylated/Hydroxymethylated DNA Quantification, respectivamente. Tecidos placentários apresentaram menores níveis de 5-mC e 5-hmC quando comparados com espermatozoides. Cotilédones de machos apresentaram maiores níveis de 5-hmC do que os de fêmeas. Os níveis de 5-mC e 5-hmC em animais Bos taurus indicus foram caracterizados pela primeira vez, o que pode contribuir para o nosso conhecimento sobre a regulação dos mecanimos epigenéticos na placenta. A presença de 5-hmC em tecidos somáticos sugerem que essa base pode ter sua própria função biológica, sendo não somente um sub-produto da oxidação da 5-mC. Esses resultados podem ser de interesse nas Tecnologias de Reprodução Assistida, especialmente na clonagem, no diagnóstico/prognóstico de placentação aberrante e viabilidade da progênie.(AU)