Fundamental features of 3D genome organization are established de novo in the early embryo, including clustering of pericentromeric regions, the folding of chromosome arms and the segregation of chromosomes into active (A-) and inactive (B-) compartments. However, the molecular mechanisms that drive de novo organization remain unknown1,2. Here, by combining chromosome conformation capture (Hi-C), chromatin immunoprecipitation with high-throughput sequencing (ChIP–seq), 3D DNA fluorescence in situ hybridization (3D DNA FISH) and polymer simulations, we show that heterochromatin protein 1a (HP1a) is essential for de novo 3D genome organization during Drosophila early development. The binding of HP1a at pericentromeric heterochromatin is required to establish clustering of pericentromeric regions. Moreover, HP1a binding within chromosome arms is responsible for overall chromosome folding and has an important role in the formation of B-compartment regions. However, depletion of HP1a does not affect the A-compartment, which suggests that a different molecular mechanism segregates active chromosome regions. Our work identifies HP1a as an epigenetic regulator that is involved in establishing the global structure of the genome in the early embryo.

BackgroundThere has been increasing research on posttraumatic stress disorder (PTSD) following childbirth in the last two decades. The literature on predictors of who develops posttraumatic stress symptoms (PSS) suggests that both vulnerability and birth factors have an influence, but many studies measure predictors and outcomes simultaneously.ObjectiveIn this context, we aimed to examine indirect and direct effects of predictors of PSS, which were measured longitudinally.MethodWe assessed women within the first days (n=353), 6 weeks, and 12 months (n=183) after having given birth to a healthy infant. The first assessment included questions on demographics, pregnancy, and birth experience. The second and third assessments contained screenings for postpartum depression, PTSD, and general mental health problems, as well as assessing social support and physical well-being. We analysed our data using structural equation modelling techniques (n=277).ResultsOur final model showed good fit and was consistent with a diathesis-stress model of PSS. Women who had used antidepressant medication in the 10 years before childbirth had higher PSS at 6 weeks, independent of birth experiences. Subjective birth experience was the early predictor with the highest total effect on later PSS. Interestingly, a probable migration background also had a small but significant effect on PSS via more episiotomies. The null results for social support may have been caused by a ceiling effect.ConclusionsGiven that we measured predictors at different time points, our results lend important support to the etiological model, namely, that there is a vulnerability pathway and a stress pathway leading to PSS. PSS and other psychological measures stayed very stable between 6 weeks and 1 year postpartum, indicating that it is possible to identify women developing problems early.Highlights of the articleOur results are consistent with a diathesis-stress model: vulnerability (antidepressant use in the previous 10 years) influenced posttraumatic stress symptoms at 6 weeks and 1 year, independently of stress (birth-related variables).The strongest predictor of posttraumatic stress symptoms 1 year postpartum was posttraumatic stress symptoms 6 weeks postpartum. This means that women who develop problems could be identified during routinely offered postpartum care.Women with a probable migration background experienced more PSS 1 year after the birth, which was an indirect effect through more episiotomies and more PSS after 6 weeks.

When preparing the evaluation of a newly designed multimedia tool for supporting preoperative education before radical prostatectomy, we realized that the standard procedure has rarely been investigated. Therefore, we performed semi-structured interviews with 30 consecutive patients the day before and 15 days after radical prostatectomy. Patients' opinion about their preoperative education is decidedly positive and demonstrates intense patient-physician interaction. All patients wanted to be informed about the procedure and possible risks. None reported to be dissatisfied. All but one of the patients (29/30) was able to ask every single question (6.5 mean). Except for signs of forgetting and a slightly altered retrospective assessment of anxiety, we have found no relevant changes over time. Preoperative education is very important to our patients. Therefore, good communication skills should be developed during medical education. A systematic patient-centered approach could further improve the quality of care.

Zygotic genome activation (ZGA) is a crucial step of embryonic development. So far, little is known about the role of chromatin factors during this process. Here, we used an in vivo RNA interference reverse genetic screen to identify chromatin factors necessary for embryonic development in Drosophila melanogaster . Our screen reveals that histone acetyltransferases (HATs) and histone deacetylases are crucial ZGA regulators. We demonstrate that Nejire (CBP/EP300 ortholog) is essential for the acetylation of histone H3 lysine-18 and lysine-27, whereas Gcn5 (GCN5/PCAF ortholog) for lysine-9 of H3 at ZGA, with these marks being enriched at all actively transcribed genes. Nonetheless, these HATs activate distinct sets of genes. Unexpectedly, individual catalytic dead mutants of either Nejire or Gcn5 can activate zygotic transcription (ZGA) and transactivate a reporter gene in vitro. Together, our data identify Nejire and Gcn5 as key regulators of ZGA.

This protocol provides specific details on how to perform Chromatin immunoprecipitation (ChIP) from Drosophila embryos. ChIP allows the matching of proteins or histone modifications to specific genomic regions. Formaldehyde-cross-linked chromatin is isolated and antibodies against the target of interest are used to determine whether the target is associated with a specific DNA sequence. This can be performed in spatial and temporal manner and it can provide information about the genome-wide localization of a given protein or histone modification if coupled with deep sequencing technology (ChIP-Seq).