The effects of the phthalate DiNP on reproduction†.

Di-isononyl phthalate (DiNP) is a high molecular weight, general purpose, plasticizer used primarily in the manufacture of polymers and consumer products. It can be metabolized rapidly and does not bioaccumulate. The primary metabolite of DiNP is monoisononyl-phthalate (MiNP) and the secondary metabolites include three oxidative derivatives of DiNP, which have been identified mainly in urine: mono-oxoisononyl phthalate (MOINP or oxo-MiNP), mono-carboxyisooctyl phthalate (MCIOP, MCOP or cx-MiNP), and mono-hydroxyisononyl phthalate (MHINP or OH-MiNP). The secondary metabolites are very sensitive biomarkers of DiNP exposure while primary metabolites are not. As the usage of DiNP worldwide increases, studies evaluating its potential reproductive toxicity are becoming more prevalent in the literature. In studies on female animals, the researchers found that the exposure to DiNP appears to induce negative effects on ovarian function and fertility in animal models. Whether or not DiNP has direct effects on the uterus is still controversial, and the effects on human reproduction require much more research. Studies on males indicate that DiNP exposure has disruptive effects on male reproduction and fertility. Occupational studies also indicate that the exposure to DiNP might induce negative effects on male reproduction, but larger cohort studies are needed to confirm this. This review presents an overview of the literature regarding the reproductive effects of exposure to DiNP.

Impact of mono(2-ethylhexyl) phthalate (MEHP) on the development of mouse embryo in vitro.

Mono(2-ethylhexyl) phthalate (MEHP) is the most studied metabolite of di(2-ethylhexyl) phthalate (DEHP), a phthalate found in cosmetics, flooring, paints, and plastics products, including toys and medical tubing. Humans are frequently exposed to this compound due to its ubiquitous presence in our environment. DEHP and MEHP are known to be endocrine-disrupting chemicals and exposure levels have been associated to decreased reproductive success. However, few studies have focused on the direct effects of MEHP on embryos. The present study investigated effects of MEHP (0.1, 1, 10, 100 and 1000 µM) on mice preimplantation embryonic development, evaluating percentage of blastocyst formation, hatching from zona pellucida, methylation-related genes, cell lineage commitment, micronucleation, and adherens junction marker at different stages of development during in vitro culture for 6 days. We show MEHP negatively impacts embryo competence by reducing blastocyst formation and hatching at 100 and 1000 µM. In addition, 100 µM MEHP increases the expression of Tet3 gene in blastocysts, which is related to a reduction of DNA methylation, an important mechanism regulating gene expression. Exposed embryos that completed the hatching process in groups 0.1, 1 and 10 µM MEHP had similar number of inner cell mass and trophectoderm cells compared to the control, while micronucleation occurrence and E-cadherin expression was not affected in exposed morulae by MEHP at 10 or 100 µM. Our results showed that high concentrations of MEHP can negatively impact embryo development. New studies unveiling the mechanism of toxicity involved and encompassing further developmental stages are warranted for further understanding.

In vitro gametogenesis from embryonic stem cells in livestock species: recent advances, opportunities, and challenges to overcome.

Pluripotent stem cells (PSC) can be stabilized in vitro from pre-implantation stage embryos (embryonic stem cells, ESC) or by reprogramming adult somatic cells (induced pluripotent stem cells, iPSC). The last decade has seen significant advances in the livestock PSC field, particularly the development of robust methods for long-term culture of PSC from several livestock species. Along with this, considerable progress has been made in understanding the states of cellular pluripotency and what they mean for cell differentiation capacity, and significant efforts are ongoing to dissect the critical signaling pathways required for the maintenance of PSC in different species and distinct states of pluripotency. Among the cell types that can be generated from PSC, the germline holds special importance as they are the genetic link between generations; and devising methods to enable in vitro gametogenesis (IVG) and produce viable gametes could revolutionize animal agriculture, wildlife conservation, and human assisted reproduction alike. Within the last decade, many pivotal studies about IVG were published using rodent models, filling some critical knowledge gaps in the field. Most importantly, the entire female reproductive cycle was reproduced in vitro from mouse ESC. Although complete male gametogenesis in vitro has not yet been reported, significant advances were made showing the capacity of germline stem cell-like cells to generate healthy offspring. In this review, we provide an overview of PSC and advances in the establishment of livestock PSC; we present the breakthroughs made in rodents regarding IVG and the current progress towards livestock IVG, including the importance of a detailed understanding of fetal germline development. Finally, we discuss some key advances that will be critical to enable this technology at scale. Given the potential impact of IVG for animal agriculture, major efforts will likely continue to be employed by research institutions and industry towards the development of methods to achieve efficient generation of gametes in vitro.

In this review, we summarize the current state of livestock embryonic stem cell establishment and the advances in production of sperm and eggs in vitro in rodents and livestock. We also discuss the potential and challenges of developing systems that support in vitro gametogenesis in livestock and the opportunities for this new technology in the reproductive field.

Regulation of RNA localization during oocyte maturation by dynamic RNA-ER association and remodeling of the ER.

Asymmetric localization of mRNAs is crucial for cell polarity and cell fate determination. By performing fractionation RNA-seq, we report here that a large number of maternal RNAs are associated with the ER in Xenopus oocytes but are released into the cytosol after oocyte maturation. We provide evidence that the majority of ER-associated RNA-binding proteins (RBPs) remain associated with the ER after oocyte maturation. However, all ER-associated RBPs analyzed exhibit reduced binding to some of their target RNAs after oocyte maturation. Our results further show that the ER is remodeled massively during oocyte maturation, leading to the formation of a widespread tubular ER network in the animal hemisphere that is required for the asymmetric localization of mRNAs in mature eggs. Thus, our findings demonstrate that dynamic regulation of RNA-ER association and remodeling of the ER are important for the asymmetric localization of RNAs during development.