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Iodine-contrast micro-computed tomography (microCT) 3D imaging provides a non-destructive and high-throughput platform for studying mouse embryo and neonate development. Here we provide protocols on preparing mouse embryos and neonates between embryonic day 8.5 (E8.5) to postnatal day 4 (P4) for iodine-contrast microCT imaging. With the implementation of the STABILITY method to create a polymer-tissue hybrid structure, we have demonstrated that not only is soft tissue shrinkage minimized but also the minimum required time for soft tissue staining with iodine is decreased, especially for E18.5 to P4 samples. In addition, we also provide a protocol on using commercially available X-CLARITY TM hydrogel solution to create the similar polymer-tissue hybrid structure on delicate early post-implantation stage (E8.5 to E14.5) embryos. With its simple sample staining and mounting processes, this protocol is easy to adopt and implement for most of the commercially available, stand-alone microCT systems in order to study mouse development between early post-implantation to early postnatal stages. © 2019 by John Wiley & Sons, Inc., (© 2019 John Wiley & Sons, Inc.)

Transposable elements (TEs) are obligate genetic parasites that propagate in host genomes by replicating in germline nuclei, thereby ensuring transmission to offspring. This selfish replication not only produces deleterious mutations-in extreme cases, TE mobilization induces genotoxic stress that prohibits the production of viable gametes. Host genomes could reduce these fitness effects in two ways: resistance and tolerance. Resistance to TE propagation is enacted by germline-specific small-RNA-mediated silencing pathways, such as the Piwi-interacting RNA (piRNA) pathway, and is studied extensively. However, it remains entirely unknown whether host genomes may also evolve tolerance by desensitizing gametogenesis to the harmful effects of TEs. In part, the absence of research on tolerance reflects a lack of opportunity, as small-RNA-mediated silencing evolves rapidly after a new TE invades, thereby masking existing variation in tolerance. We have exploited the recent historical invasion of the Drosophila melanogaster genome by P-element DNA transposons in order to study tolerance of TE activity. In the absence of piRNA-mediated silencing, the genotoxic stress imposed by P-elements disrupts oogenesis and, in extreme cases, leads to atrophied ovaries that completely lack germline cells. By performing quantitative trait locus (QTL) mapping on a panel of recombinant inbred lines (RILs) that lack piRNA-mediated silencing of P-elements, we uncovered multiple QTL that are associated with differences in tolerance of oogenesis to P-element transposition. We localized the most significant QTL to a small 230-kb euchromatic region, with the logarithm of the odds (LOD) peak occurring in the bruno locus, which codes for a critical and well-studied developmental regulator of oogenesis. Genetic, cytological, and expression analyses suggest that bruno dosage modulates germline stem cell (GSC) loss in the presence of P-element activity. Our observations reveal segregating variation in TE tolerance for the first time, and implicate gametogenic regulators as a source of tolerant variants in natural populations., Competing Interests: The authors have declared that no competing interests exist.

Background: Although simulation is now used in other areas of obstetrics and gynaecology, its utility in the training of an uncomplicated vaginal delivery is surprisingly under-explored. Here we describe our experience integrating simulation into the third-year Obstetrics and Gynaecology (OB/GYN) clerkship., Methods: In 2013/14, at the start of each 4-week OB/GYN clerkship, each third-year student participated in a 90-minute vaginal delivery simulation session using the Noelle(®) simulator. Upon completion of the clerkship, they were surveyed using a five-point Likert scale questionnaire (1, inferior; 5, superior) to assess self-perceived training adequacy, clinical preparedness and number of deliveries performed during the clerkship. Students who completed the clerkship in 2012/13, before the introduction of the simulation, were also surveyed to serve as a comparison group. Survey scores and number of deliveries performed were compared between the two cohorts of students., Results: The 2013/14 cohort (n = 98) who received simulation training gave their training in vaginal deliveries an average rating of 4.1, versus 2.7 for the 2012/13 cohort that did not receive the simulation (n = 80; p < 0.001). Self-perceived preparedness to perform a vaginal delivery was 4.0 in the 2013/14 cohort, versus 3.0 in the 2012/13 cohort (p < 0.001). There was no difference in the number of deliveries performed between the cohorts., Discussion: Students that received simulation rated their training adequacy and readiness to perform a vaginal delivery higher than students that did not receive training. Simulation did not increase participation in real-life deliveries. The utility of simulation in the training of an uncomplicated vaginal delivery is under-explored., (© 2015 John Wiley & Sons Ltd.)

Purpose: Single umbilical artery (SUA) has been associated with an increased risk of congenital heart disease (CHD). Women carrying fetuses with an SUA are often referred for fetal echocardiography, but data to support the need for this testing remain controversial., Methods: A retrospective review of the records for all women carrying fetuses with an SUA who had undergone fetal echocardiography between 2009 and 2012 at our center was performed. Data on the maternal and fetal risk factors for CHD were collected, and the fetuses were categorized into three groups: low risk (LR; an SUA with no additional risk factors for CHD), moderate risk (MR; an SUA with one additional risk factor for CHD), and high risk (HR; an SUA with two or more additional risk factors for CHD)., Results: In total, 101 such patients were identified: 69 LR, 26 MR, and 6 HR. No fetuses in the LR group, three in the MR group, and two in the HR group had CHD (p = 0.0005)., Conclusions: An SUA in an LR fetus did not increase the risk of CHD in our cohort, whereas an SUA in the presence of additional risk factors was associated with significantly increased risk for CHD. Our results suggest that referral for a fetal echocardiogram is indicated for women carrying fetuses with an SUA when additional risk factors for CHD are present. In an LR fetus with an SUA, however, echocardiography may not provide additional benefit unless CHD is suggested on screening obstetric sonography., (© 2015 Wiley Periodicals, Inc.)