So far, the characteristics of a good quality egg have been elusive, similar to the nature of the physiological, cellular, and molecular cues leading to its production both in vivo and in vitro. Current understanding highlights a strong and complex interdependence between the follicular cells and the gamete. Secreted factors induce cellular responses in the follicular cells, and direct exchange of small molecules from the cumulus cells to the oocyte through gap junctions controls meiotic arrest. Studying the interconnection between the cumulus cells and the oocyte, we previously demonstrated that the somatic cells also contribute transcripts to the gamete. Here, we show that these transcripts can be visualized moving down the transzonal projections (TZPs) to the oocyte, and that a time course analysis revealed progressive RNA accumulation in the TZPs, indicating that RNA transfer occurs before the initiation of meiosis resumption under a timetable fitting with the acquisition of developmental competence. A comparison of the identity of the nascent transcripts trafficking in the TZPs, with those in the oocyte increasing in abundance during maturation, and that are present on the oocyte's polyribosomes, revealed transcripts common to all three fractions, suggesting the use of transferred transcripts for translation. Furthermore, the removal of potential RNA trafficking by stripping the cumulus cells caused a significant reduction in maturation rates, indicating the need for the cumulus cell RNA transfer to the oocyte. These results offer a new perspective to the determinants of oocyte quality and female fertility, as well as provide insight that may eventually be used to improve in vitro maturation conditions.

Early embryonic development, spanning fertilization to blastocyst hatching, is a very dynamic developmental window that is characterized, especially in large mammals, by a period of transcriptional incompetence that ends during the maternal to embryonic transition (MET). Prior to the MET, the first cell cycles are supported by stored RNA and proteins pools accumulated during oogenesis. Therefore, RNA and protein content are different between developmental stages. It is also known that the stability of the stored mRNA and the mechanisms for translation recruitment are partly controlled by the length of the poly(A) tail. To date, little is known about RNA and protein content fluctuations during the pre-hatching period. In this report we present measurements of total RNA, mRNA, poly(A) bearing mRNA and protein contents, as well as estimations of the proportions of both mRNA fractions to total RNA contents within these developmental stages. We found that while the ontogenic profiles of the different transcript contents were expected, their amounts were considerably lower than the reported values. Additionally, low 28S rRNA abundance and a tendency for diminishing protein content prior to the MET, suggest a limited potential for ribosomal turnover and translation. We consider the overall fluctuations in RNA and protein contents to be reference points that are essential for downstream interpretation of gene expression data across stages whether it be through candidates or high throughput approaches.

Although the oocyte is the largest cell in the body and an unavoidable phase in life, its physiology is still poorly understood, and other cell types provide little insight into its unique nature. Even basic cellular functions in the oocyte such as energy metabolism are not yet fully understood. It is known that the mitochondria of the female gamete exhibit an immature form characterized by limited energy production from glucose and oxidative phosphorylation. We show that the bovine oocyte uses alternative means to maintain ATP production during maturation, namely, the adenosine salvage pathway. Meiosis resumption is triggered by destruction of cyclic AMP by phosphodiesterases producing adenosine monophosphate that is converted into ATP by adenylate kinases and creatine kinases. Inhibition of these enzymes decreased ATP production, and addition of their substrates restored ATP production in denuded oocytes. Addition of phosphocreatine to the oocyte maturation medium influenced the phenotype of the resulting blastocysts. We propose a model in which adenylate kinases and creatine kinases act as drivers of ATP production from added AMP during oocyte maturation.

Now recognised as part of the cellular transcriptome, the function of long non-coding (lnc) RNA remains unclear. Previously, we found that some lncRNA molecules in bovine embryos are highly responsive to culture conditions. In view of a recent demonstration that lncRNA may play a role in regulating important functions, such as maintenance of pluripotency, modification of epigenetic marks and activation of transcription, we sought evidence of its involvement in embryogenesis. Among the numerous catalogued lncRNA molecules found in oocytes and early embryos of cattle, three candidates chosen for further characterisation were found unexpectedly in the cytoplasmic compartment rather than in the nucleus. Transcriptomic survey of subcellular fractions found these candidates also associated with polyribosomes and one of them spanning transzonal projections between cumulus cells and the oocyte. Knocking down this transcript in matured oocytes increased developmental rates, leading to larger blastocysts. Transcriptome and methylome analyses of these blastocysts showed concordant data for a subset of four genes, including at least one known to be important for blastocyst survival. Functional characterisation of the roles played by lncRNA in supporting early development remains elusive. Our results suggest that some lncRNAs play a role in translation control of target mRNA. This would be important for managing the maternal reserves within which is embedded the embryonic program, especially before embryonic genome activation.

Previous studies have shown that patients with a low socioeconomic position undergoing various surgical procedures are at higher risk for postoperative complications and worse survival outcomes than patients with a high socioeconomic position. Complication and mortality rates are also higher for individuals from lower social classes treated for myocardial infarction, certain cancers, and other serious conditions. Some studies suggest an association between socioeconomic position and postsurgical complications among women undergoing hysterectomy.This register-based cohort study was designed to determine whether there is an association between socioeconomic position and risk of complications following hysterectomy and to investigate the role of lifestyle factors and comorbidity on this association. Participants included nearly all Danish women (n = 22,150) with a benign elective hysterectomy registered in the Danish Hysterectomy Database between 2004 and 2008. The association between 3 selected measures of socioeconomic position (education, employment, and income) and complications was assessed using multiple logistic regression models. The risk of infection, hospitalization, readmission, and reoperation after hysterectomy was also examined in women of different socioeconomic status.Complications following hysterectomy occurred in 17% of the women. The risk of infection, complications, and readmission was higher among women with less high school education and unemployed women than women with more than high school education and employed women. Unemployment (but not low education) was associated with higher odds of hospitalization of more than 4 days. Most of the social differences appeared to be due to lifestyle factors (smoking and body mass index) and comorbidity. However, the association between low education and the overall rate of complications remained unexplained. The higher odds of infection, complications, and hospitalization of more than 4 days among unemployed women could only be partially explained by differences in lifestyle and comorbidity status.These findings show that the risk of complications following hysterectomy is significantly higher in women with a low socioeconomic position than in women with a high socioeconomic position. Differences in complications among women with low socioeconomic status can be partially explained by unhealthy lifestyle and presence of comorbidity. EDITORIAL COMMENT(Most readers of the Survey are aware of the sociodemographic disparities in access to care, screening rates, and outcomes across a wide range of conditions facing women in the United States. Hysterectomy risk factors, rates, routes, postoperative complications, and long-term outcomes have been found to vary substantially across groups of different race/ethnicity, household income, educational attainment, insurance status, and occupation. These explanatory factors are associated with each other, making it hard to determine which factors contribute the most to racial/ethnic differences.The authors of the study...