RESUMO

This review is intended to draw attention to the importance of the culture media composition on the health of the embryos, fetuses, newborns, and adults derived from assisted reproductive technologies (ART). Although current research and industry trends are to use chemically defined media because of their suitability for manufacturing, commercialization, and regulatory purposes, compelling evidence indicates that those media fail to adequately account for the biological demands of early embryogenesis. Here, we list the main undesirable consequences of the ART described in the literature and results we and others have obtained over the past decade exploring an alternative and more natural way to support embryo growth in vitro: inclusion of endogenous reproductive fluids as additives in the ART culture media for pigs, cows, and humans. This review systematically assesses the pros and cons of using reproductive fluid additives, as well as the requirements to implement this approach in the future.

RESUMO

Multi-locus methylation defects (MLMDs) in imprinted loci have been reported in Beckwith-Wiedemann Syndrome (BWS). Large offspring syndrome (LOS), a phenotypic subgroup of abnormal offspring syndrome (AOS), is considered a molecular and phenotypic model for BWS. Both LOS and BWS have presented epigenetic defects in some common imprinted loci. In this study, methylation-specific restriction digestion assay - quantitative PCR was used to analyze the DNA methylation pattern in differentially methylated regions (DMRs) of the H19 (H19-DMR), KCNQ1OT1 (KvDMR1) and PEG1/MEST (PEG1-DMR) genes in bovine clone tissues from calves that did not survive after birth. Individual and tissue-specific changes in DNA methylation levels in the bovine KvDMR1, H19-DMR, and PEG1-DMR were observed. In contrast to what has been reported in the literature on BWS and AOS/LOS, the KvDMR1 showed gain (GOM) and loss (LOM) of DNA methylation. LOM and GOM events were found in the DMRs studied in animals produced by the same nucleus donor cell line. This is the first report of epimutations in the PEG1-DMR and GOM at the KvDMR1 found in bovine clones. The findings showed that epigenetic modification in imprinted loci in cloned cattle occurred in a multi-locus pattern similar to that seen in human imprinting disorders. Other multi-locus analyzes must be done to elucidate the MLMD pattern in AOS in bovine clones.

Assuntos

RESUMO

This review is intended to draw attention to the importance of the culture media composition on the health of the embryos, fetuses, newborns, and adults derived from assisted reproductive technologies (ART). Although current research and industry trends are to use chemically defined media because of their suitability for manufacturing, commercialization, and regulatory purposes, compelling evidence indicates that those media fail to adequately account for the biological demands of early embryogenesis. Here, we list the main undesirable consequences of the ART described in the literature and results we and others have obtained over the past decade exploring an alternative and more natural way to support embryo growth in vitro: inclusion of endogenous reproductive fluids as additives in the ART culture media for pigs, cows, and humans. This review systematically assesses the pros and cons of using reproductive fluid additives, as well as the requirements to implement this approach in the future.(AU)

Assuntos

RESUMO

The in vitro production of bovine embryos by in vitro fertilization or nuclear transfer procedures is a powerful tool in wide use for scientific, conservationist and commercialpurposes. However, developmental abnormalities are unpredictable consequences of such in vitro embryo manipulations, which may interfere with the pattern of fetal and placentalgrowth and life ex utero, in a set of symptoms collectively called Large Offspring Syndrome (LOS). The economical significance of the syndrome is associated with increased rates ofpregnancy losses, placental and fetal aberrations that culminate in abortion, hydrops of the fetal membranes, prolonged gestation, diminished signs of parturition, dystocia, and birth of large calves with lower postnatal survival. Lower pregnancy rates with higher gestational and postnatal losses represent significant economical losses for a lower prolificacy. The understanding of mechanisms of prenatal growth in normal development and in those related to the syndrome will be of significance for prevention or attenuation of abnormalities ofcommon occurrence in cattle, with potential direct scientific and economical implications.

La producción in vitro de embriones por fertilización in vitro o por procedimientos de transferenciade núcleos es una herramienta poderosa utilizada ampliamente para propósitoscientíficos, conservacionistas y comerciales. Sin embargo, las alteraciones del desarrollo son consecuencias impredecibles de tales manipulaciones in vitro, que pueden interferir con el patrón de de crecimiento fetal y placentario y la vida ex utero, que se agrupan en unos síntomas conocidos colectivamente como el síndrome del ternero grande (LOS). La importancia económica del síndrome está asociada con un incremento en las pérdidas gestacionales, aberraciones placentarias y fetales que culminan en aborto, condiciones hidópicas de las membranas fetales, gestaciones prolongadas, disminución en los signos de parto, distocias, y nacimiento de terneros grandes con baja supervivencia postnatal. Las bajastasas de preñez con las altas tasas de pérdidas gestacionales representan pérdidas económicas significativas por baja prolificidad. El entendimiento de los mecanismos de crecimientoprenatal durante el desarrollo normal y en aquellos relacionados con el síndrome sería muy significativo en la prevención, atenuación de las anormalidades de ocurrencia común en el ganado, con implicaciones directas a nivel científico y económico.

Assuntos