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- Human oocyte meiotic maturation is associated with a specific profile of alternatively spliced transcript isoformsPublication . Cornet‐Bartolomé, David; Barragán, Montserrat; Zambelli, Filippo; Ferrer‐Vaquer, Anna; Tiscornia, Gustavo; Balcells, Susanna; Rodriguez, Amelia; Grinberg, Daniel; Vassena, RitaThe transition from a transcriptionally active state (GV) to a transcriptionally inactive state (mature MII oocytes) is required for the acquisition of oocyte developmental competence. We hypothesize that the expression of specific genes at the in vivo matured (MII) stage could be modulated by posttranscriptional mechanisms, particularly regulation of alternative splicing (AS). In this study, we examined the transcriptional activity of GV oocytes after ovarian stimulation followed by oocyte pick-up and the landscape of alternatively spliced isoforms in human MII oocytes. Individual oocytes were processed and analyzed for transcriptional activity (GV), gene expression (GV and MII), and AS signatures (GV and MII) on HTA 2.0 microarrays. Samples were grouped according to maturation stage, and then subgrouped according to women's age and antral follicular count (AFC); array results were validated by quantitative polymerase chain reaction. Differentially expressed genes between GV and MII oocytes clustered mainly in biological processes related to mitochondrial metabolism. Interestingly, 16 genes that were related to the regulation of transcription and mitochondrial translation showed differences in alternatively spliced isoform profiles despite not being differentially expressed between groups. Altogether, our results contribute to our understanding of the role of AS in oocyte developmental competence acquisition.
- Vaginal microbiota profile at the time of embryo transfer does not affect live birth rate in IVF cycles with donated oocytesPublication . Vergaro, Paula; Tiscornia, Gustavo; Barragan, Montserrat; Garcia, Desiree; Rodriguez, Amelia; Santalo, Josep; Vassena, RitaResearch question: What is the relationship between the vaginal microbiota profile at the time of embryo transfer and live birth rates in women undergoing IVF/intracytoplasmic sperm injection (ICSI) with donated oocytes? Design: One hundred and fifty Caucasian women receiving donated oocytes were prospectively included in the study from March 2017 to January 2018. Samples of vaginal fluid were taken immediately before transfer of a fresh single blastocyst and genomic DNA (gDNA) was extracted. Bacterial load as well as the presence of four lactobacilli (L. crispatus, L. gasseri, L. jensenii and L. iners) and species associated with bacterial vaginosis (Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Prevotella spp. - here collectively termed BVB) were determined by quantitative polymerase chain reaction. Vaginal microbiota profiles for each patient were characterized and correlated with reproductive results. Results: Although bacterial load was variable, a majority of samples were dominated by a single species (80.7%, 121/150). Most samples (76.7%, 115/150) were dominated by Lactobacillus spp., while 23.3% (35/150) were dominated by bacteria associated with bacterial vaginosis. The distribution of microbiota profiles among women who achieved a live birth and women who did not was similar (P = 0.43). Interestingly, we found a significantly higher proportion of samples dominated by L. crispatus- in women achieving live birth compared with those who did not (P = 0.021)
- Trophoblast attachment to the endometrial epithelium elicits compartment-specific transcriptional waves in an in-vitro modelPublication . Vergaro, Paula; Tiscornia, Gustavo; Zambelli, Filippo; Rodríguez, Amelia; Santaló, Josep; Vassena, RitaImplantation is a major bottleneck in human reproduction (Polanski et al., 2014). The average implantation rate for an embryo ranges from 30% to 40% (Coughlan et al., 2014). Recurrent implantation failure (RIF) is estimated to occur in approximately 4% of IVF cycles (Koot et al., 2012), although estimates vary because there are several somewhat different definitions of RIF in the literature. Implantation of the blastocyst in the receptive endometrium is a sequential process involving apposition, attachment and invasion that precedes the establishment of pregnancy (Wang and Dey, 2006). Successful implantation requires embryo competence and endometrial receptivity, both of which are dynamic and highly regulated states (Wang and Dey, 2006). In addition to genetic disorders (which are a major cause of implantation failure and miscarriage), embryo competence, quality and ultimately developmental potential depend on the embryo achieving the correct regulatory, signalling and metabolic states (Fu et al., 2009; Hourvitz et al., 2006; Lundin et al., 2001; Simon and Laufer, 2012; Sjoblom et al., 2006). A key determinant of these embryonic states is their underlying transcriptional dynamics; for instance, waves of embryonic transcriptional activation direct early development and the symmetry breaking needed for cell fate specification (Shi et al., 2015; Vassena et al., 2011).