Search

Summary Primordial germ cells (PGCs) arise from cells of the post-implantation epiblast in response to cytokine signaling. PGC development can be recapitulated in vitro by differentiating epiblast-like cells (EpiLCs) into PGC-like cells (PGCLCs) through cytokine exposure. Interestingly, the cytokine requirement for PGCLC induction can be bypassed by enforced expression of the transcription factor (TF) NANOG. However, the underlying mechanisms are not fully elucidated. Here, we show that NANOG mediates Otx2 downregulation in the absence of cytokines and that this is essential for PGCLC induction by NANOG. Moreover, the direct NANOG target gene Esrrb, which can substitute for several NANOG functions, does not downregulate Otx2 when overexpressed in EpiLCs and cannot promote PGCLC specification. However, expression of ESRRB in Otx2+/− EpiLCs rescues emergence of PGCLCs. This study illuminates the interplay of TFs occurring at the earliest stages of PGC specification., Highlights • NANOG overexpression induces cytokine-free PGCLC specification by repressing Otx2 • Enforced OTX2 expression prevents NANOG-induced germline entry • ESRRB overexpression cannot repress Otx2 or induce cytokine-free germline entry • Otx2 heterozygosity enables ESRRB to induce cytokine-free PGCLC specification, Vojtek and colleagues show that NANOG represses Otx2 to induce cytokine-free specification of primordial germ cell-like cells (PGCLCs). OTX2 levels are critical for PGCLC induction, as sustained OTX2 expression prevents NANOG-induced differentiation. Although ESRRB can functionally substitute for NANOG in other processes, ESRRB does not repress Otx2 and cannot induce cytokine-free PGCLC specification unless the Otx2 expression is halved.

The self-renewal efficiency of mouse embryonic stem cells (ESCs) is determined by the concentration of the transcription factor NANOG. While NANOG binds thousands of sites in chromatin, the regulatory systems that control DNA binding are poorly characterised. Here, we show that NANOG is phosphorylated by casein kinase I, and identify target residues. Phosphomimetic substitutions at phosphorylation sites within the homeodomain (S130 and S131) have site-specific functional effects. Phosphomimetic substitution of S130 abolishes DNA binding by NANOG and eliminates LIF-independent self-renewal. In contrast, phosphomimetic substitution of S131 enhances LIF-independent self-renewal, without influencing DNA binding. Modelling the DNA-homeodomain complex explains the disparate effects of these phosphomimetic substitutions. These results indicate how phosphorylation may influence NANOG homeodomain interactions that underpin ESC self-renewal.

Graphical abstract, Highlights • TET1 and NANOG interact via multiple independent binding regions. • TET1 and NANOG interactions are mediated by aromatic and hydrophobic residues. • TET1 residues that bind NANOG are highly conserved in mammals. • Co-localisation of TET1 and NANOG on chromatin is enriched at NANOG target genes. • NANOG and TET1 have regulatory roles in maintaining and reprogramming pluripotency., The DNA demethylase TET1 is highly expressed in embryonic stem cells and is important both for lineage commitment, and reprogramming to naïve pluripotency. TET1 interacts with the pluripotency transcription factor NANOG which may contribute to its biological activity in pluripotent cells. However, how TET1 interacts with other proteins is largely unknown. Here, we characterise the physical interaction between TET1 and NANOG using embryonic stem cells and bacterial expression systems. TET1 and NANOG interact through multiple binding sites that act independently. Critically, mutating conserved hydrophobic and aromatic residues within TET1 and NANOG abolishes the interaction. On chromatin, NANOG is predominantly localised at ESC enhancers. While TET1 binds to CpG dinucleotides in promoters using its CXXC domain, TET1 also binds to enhancers, though the mechanism involved is unknown. Comparative ChIP-seq analysis identifies genomic loci bound by both TET1 and NANOG, that correspond predominantly to pluripotency enhancers. Importantly, around half of NANOG transcriptional target genes are associated with TET1-NANOG co-bound sites. These results indicate a mechanism by which TET1 protein may be targeted to specific sites of action at enhancers by direct interaction with a transcription factor.

RESF1 supports ESC self-renewal by raising expression of transmembrane LIF receptor and key pluripotency transcription factors and increases in vitro primordial germ cell differentiation efficiency., Retroelement silencing factor 1 (RESF1) interacts with the key regulators of mouse embryonic stem cells (ESCs) OCT4 and NANOG, and its absence results in sterility of mice. However, the function of RESF1 in ESCs and germline specification is poorly understood. In this study, we used Resf1 knockout cell lines to determine the requirements of RESF1 for ESC self-renewal and for in vitro specification of ESCs into primordial germ cell-like cells (PGCLCs). We found that deletion of Resf1 in ESCs cultured in serum and LIF reduces self-renewal potential, whereas episomal expression of RESF1 has a modest positive effect on ESC self-renewal. In addition, RESF1 is not required for the capacity of NANOG and its downstream target ESRRB to drive self-renewal in the absence of LIF. However, Resf1 deletion reduces the efficiency of PGCLC differentiation in vitro. These results identify Resf1 as a novel player in the regulation of pluripotent stem cells and germ cell specification.

Objectives To report human papillomavirus (HPV) testing patterns and rates of oncogenic HPV-positivity for specimens submitted during the first 6 months after the National Cervical Screening Program switched from cytology- to primary HPV-based screening. Design, participants Retrospective cross-sectional review of 195 606 specimens submitted for HPV testing, 1 December 2017 - 31 May 2018. Setting Large community-based general pathology laboratory in metropolitan Sydney. Main outcome measures Prevalence of oncogenic HPV types (all, HPV16/18, non-HPV16/18) by reason for HPV test (primary screening, non-screening); for oncogenic HPV-positive women in the age band recommended for primary HPV screening (25-74 years), prevalence of cytologic abnormality and rates of 12-month follow-up and colposcopy recommendations. Results 195 606 samples were received: 157 700 (80.6%) for primary screening, 37 906 (19.4%) for non-screening tests. Oncogenic HPV was detected in 8.1% of screening tests (95% CI, 7.9-8.2%) and 20.9% of non-screening tests (95% CI, 20.5-21.3%); 35.5% (95% CI, 34.7-36.4%) of women of recommended screening age with positive oncogenic HPV screening test results also had a cytologic abnormality. The proportion of HPV16/18-positive samples with high grade abnormality was 15.3% (95% CI, 14.2-16.6%); for samples positive for other oncogenic HPV types, the proportion was 6.3% (95% CI, 5.8-6.8%). Repeat HPV testing after 12 months was recommended for 5.4% (95% CI, 5.3-5.5%) and direct colposcopy for 2.6% (95% CI, 2.5-2.7%) of screened women aged 25-74 years. Conclusions High grade cytologic abnormalities were more common in women positive for HPV16/18, supporting their higher risk classification. Colposcopy referral rates were higher than during primary cytology-based testing, as predicted by clinical trial and modelling data. The prevalence of HPV was much higher in non-screening than in primary screening samples. Our findings indicate the renewed program is performing as expected during the initial HPV screening round.

SummaryPrimordial germ cells (PGCs) are induced in the embryo by signals, including BMP emanating from extra-embryonic ectoderm, that act on cells in the post-implantation epiblast. PGC development can be recapitulated in vitro through the exposure of epiblast-like cells (EpiLCs) to appropriate cytokines, resulting in differentiation into PGC-like cells (PGCLCs). Interestingly, the requirement for cytokines to induce PGCLCs can be bypassed by enforced expression of the transcription factor (TF) NANOG. However, the underlying mechanisms are not fully elucidated. Here, we show that Otx2 downregulation is essential to enable NANOG to induce PGCLC formation. Moreover, while previous work has shown that the direct NANOG target gene Esrrb can substitute for several functions of NANOG, enforced expression of ESRRB cannot promote PGCLC specification from EpiLCs. This appears to be due to differential downregulation of Otx2 by NANOG and ESRRB, since induction of ESRRB in Otx2+/- EpiLCs activates expression of the core PGC TFs, Blimp1, Prdm14 and Ap2γ and emergence of PGCLCs. This study illuminates the interplay of TFs occurring at the earliest stages of PGC specification from a state of competence.

SummaryRetroelement silencing factor 1 (RESF1) interacts with the key regulators of mouse embryonic stem cells (ESCs) OCT4 and NANOG, and its absence results in sterility of mice. However, the function of RESF1 in ESCs and germ line specification is poorly understood. In this study, we used Resf1 knockout cell lines to determine the requirements of RESF1 for ESCs self-renewal and for in vitro specification of ESCs into primordial germ cell-like cells (PGCLCs). We found that deletion of Resf1 in ESCs cultured in serum and LIF reduces self-renewal potential whereas episomal expression of RESF1 has a modest positive effect on ESC self-renewal. In addition, RESF1 is not required for the capacity of NANOG and its downstream target ESRRB to drive self-renewal in the absence of LIF. However, Resf1 deletion reduces efficiency of PGCLC differentiation in vitro. These results identify Resf1 as a novel player in the regulation of pluripotent stem cells and germ cell specification.

The ventral tegmental area (VTA) contains dopamine neurons intermixed with GABA-releasing (expressing vesicular GABA transporter, VGaT), glutamate-releasing (expressing vesicular glutamate transporter, VGluT2), and co-releasing (co-expressing VGaT and VGluT2) neurons. By delivering INTRSECT viral vectors into VTA of double vglut2-Cre/vgat-Flp transgenic mice, we targeted specific VTA cell populations for ex vivo recordings. We found that VGluT2+ VGaT− and VGluT2+ VGaT+ neurons on average had relatively hyperpolarized resting membrane voltage, greater rheobase, and lower spontaneous firing frequency compared to VGluT2− VGaT+ neurons, suggesting that VTA glutamate-releasing and glutamate-GABA co-releasing neurons require stronger excitatory drive to fire than GABA-releasing neurons. In addition, we detected expression of Oprm1mRNA (encoding μ opioid receptors, MOR) in VGluT2+ VGaT− and VGluT2− VGaT+ neurons, and their hyperpolarization by the MOR agonist DAMGO. Collectively, we demonstrate the utility of the double transgenic mouse to access VTA glutamate, glutamate-GABA and GABA neurons, and show some electrophysiological heterogeneity among them.Impact StatementSome physiological properties of VTA glutamate-releasing and glutamate-GABA co-releasing neurons are distinct from those of VTA GABA-releasing neurons. μ-opioid receptor activation hyperpolarizes some VTA glutamate-releasing and some GABA-releasing neurons.

In mammals, the pre-gastrula proximal epiblast gives rise to primordial germ cells (PGCs) or somatic precursors in response to BMP4 and WNT signaling. Entry into the germline requires activation of a naïve-like pluripotency gene regulatory network (GRN). Recent work has shown that suppression of OTX2 expression in the epiblast by BMP4 allows cells to develop a PGC fate in a precise temporal window. However, the mechanisms by which OTX2 suppresses PGC fate are unknown. Here, we show that, in mice, OTX2 prevents epiblast cells from activating the pluripotency GRN by direct repression of Oct4 and Nanog. Loss of this control during PGC differentiation in vitro causes widespread activation of the pluripotency GRN and a deregulated response to LIF, BMP4 and WNT signaling. These abnormalities, in specific cell culture conditions, result in massive germline entry at the expense of somatic mesoderm differentiation. Increased generation of PGCs also occurs in mutant embryos. We propose that the OTX2-mediated repressive control of Oct4 and Nanog is the basis of the mechanism that determines epiblast contribution to germline and somatic lineage.

The DNA demethylase TET1 is highly expressed in embryonic stem cells. Knockout experiments indicate that TET1 is important for lineage commitment, and paradoxically, also for reprogramming to naïve pluripotency. TET1 binds to promoters through a CXXC domain which recognises unmethylated CpG dinucleotides. TET1 also binds to enhancers, presumably via interactions with partner proteins. The transcription factor NANOG interacts with TET1 and is predominantly localised at enhancers in ESCs. Therefore, NANOG may contribute to TET1 biological activity in pluripotent cells. However, the regions of TET1 involved in protein-protein interactions are mostly unknown. Here, we characterise the physical interaction between TET1 and NANOG using embryonic stem cells and bacterial expression systems. TET1 and NANOG interact through multiple binding sites that act independently. Critically, mutating conserved hydrophobic and aromatic residues within TET1 and NANOG abolishes the interaction. Comparative ChIP-seq analysis identifies genomic loci bound by both TET1 and NANOG, that correspond predominantly to pluripotency enhancers. Importantly, around half of NANOG transcriptional target genes are associated with TET1-NANOG co-bound sites. These results indicate a mechanism by which TET1 protein is targeted to specific sites of action at enhancers by direct interaction with a transcription factor.HighlightsNANOG and TET1 have regulatory roles in maintaining and reprogramming pluripotencyTET1 and NANOG interact via multiple independent binding regionsTET1 and NANOG interactions are mediated by aromatic and hydrophobic residuesTET1 residues that bind NANOG are highly conserved in mammalsCo-localisation of TET1 and NANOG on chromatin is enriched at NANOG target genes

The pluripotency transcription factors (TFs) Nanog, Sox2, and Oct4 are at the centre of the gene regulatory network that controls cell identity in embryonic stem (ES) cells. However, the mechanisms by which these factors control cell fate, and their interactions with one another are not fully understood. Here we combine biophysical and novel biochemical assays to assess how these factors interact with each other quantitatively. A confocal microscopy method to detect binding of a target protein to a fluorescently labelled partner (coimmunoprecipitated bead imaging microscopy [CBIM]) is presented and used to demonstrate homotypic binding of Nanog and heterotypic binding between Nanog and Sox2 and between Nanog and Oct4. Using fluorescence correlation spectroscopy we show that in solution, Nanog but not Oct4 or Sox2 can form homomultimers. However, both Sox2 and Oct4 can form heterotypic multimers with Nanog in a manner that depends on the presence of tryptophan residues within the Nanog tryptophan repeat. Fluorescence Cross Correlation Spectroscopy shows the affinity of Nanog for dimer formation is in the order Sox2 > Nanog > Oct4. Importantly, live cell analysis demonstrates the existence of Nanog homomultimers in vivo. Together these findings extend understanding of the molecular interactions occurring between these central mediators of the pluripotency gene regulatory network at the single-molecule level.

The successful segregation of germ cells from somatic lineages is vital for sexual reproduction and species survival. In the mouse, primordial germ cells (PGCs), precursors of all germ cells, are induced from the post-implantation epiblast1. Induction requires BMP4 signalling to prospective PGCs2 and the intrinsic action of PGC transcription factors3–6. However, the molecular mechanisms that connect BMP4 to induction of the PGC transcription factors that are responsible for segregating PGCs from somatic lineages are unknown. Here we show that the transcription factor OTX2 is a key regulator of these processes. Downregulation of Otx2 precedes the initiation of the PGC programme both in vitro and in vivo. Deletion of Otx2 in vitro markedly increases the efficiency of PGC-like cell differentiation and prolongs the period of PGC competence. In the absence of Otx2 activity, differentiation of PGC-like cells becomes independent of the otherwise essential cytokine signals, with germline entry initiating even in the absence of the PGC transcription factor BLIMP1. Deletion of Otx2 in vivo increases PGC numbers. These data demonstrate that OTX2 functions repressively upstream of PGC transcription factors, acting as a roadblock to limit entry of epiblast cells to the germline to a small window in space and time, thereby ensuring correct numerical segregation of germline cells from the soma. The transcription factor OTX2 ensures that germline induction is initially kept in check and only proceeds after OTX2 downregulation.

The release of the United Nations Sustainable Development Goals and the Paris Climate Change agreement highlighted the importance of global sustainability internationally. Here, we outline a vision and strategies for developing northern Australia that demonstrate how a focus on sustainable prosperity can both expand historical approaches and current government plans and integrate the biophysical realities with the social, political, and cultural characteristics of the region. We highlight examples of the significant horizontal and vertical integration opportunities that this expanded vision and related strategies provide for (a) land (carbon farming, targeted food production systems, and native title arrangements); (b) water (water resources management); (c) energy (renewable energy production, storage, and distribution); (d) workforce (culturally appropriate ecotourism, Indigenous ranger programs, and protected area management); (e) knowledge services (health care and innovative employment opportunities); and (f) governance (greater participatory governance). We found that realisation of even 10% of these emerging opportunities over the next 10 years alone could result in economic growth worth over AUD 15 billion and 15,000+ jobs for northern Australia as well as the further ecological and social benefits derived from a sustainable prosperity strategy.

SummaryPluripotent cells reorganise themselves into an epithelium before they initiate differentiation, but it is not clear how these two events are mechanistically linked. Here we use quantitative imaging approaches to measure cellular rearrangements that accompany exit from naive pluripotency. We show that competence to epithelialise, like competence to differentiate, is a regulated process. The pro-differentiation transcription factor Tcf15 prospectively identifies cells that are competent to epithelialise. We identify early upregulation of the laminin receptor integrin alpha3 prior to differentiation and show that Tcf15 helps to regulate this change. Finally, we show that Tcf15 identifies and is required for efficient differentiation of a primed subpopulation of pluripotent cells. We conclude that competence to epithelialise is actively regulated and linked to differentiation-competence through the transcription factor Tcf15.

Mouse primordial germ cells (PGCs), originate from the early post-implantation epiblast in response to BMP4 secreted by the extraembryonic ectoderm. However, how BMP4 acts here has remained unclear. Recent work has identified the transcription factor (TF), OTX2 as a key determinant of the segregation of the germline from the soma. OTX2 is expressed ubiquitously in the early post-implantation epiblast, decreasing rapidly in cells that initiate the PGC programme. Otx2 mRNA is also rapidly repressed by BMP4 in vitro, in germline competent cells. Supporting a model in which BMP4 represses Otx2, enforcing sustained OTX2 expression in competent cells blocks germline entry. In contrast, Otx2-null epiblast cells enter the germline with increased efficiency in vitro and in vivo and can do so independently of BMP4. Also, Otx2-null cells can initiate germline entry even without the crucial PGC TF, BLIMP1. In this review, we survey recent advances and propose hypotheses concerning germline entry.

Expression of TET proteins in pluripotent cell types is visualised by epitope tagging of endogenous alleles., Tet1, Tet2, and Tet3 encode DNA demethylases that play critical roles during stem cell differentiation and reprogramming to pluripotency. Although all three genes are transcribed in pluripotent cells, little is known about the expression of the corresponding proteins. Here, we tagged all the endogenous Tet family alleles using CRISPR/Cas9, and characterised TET protein expression in distinct pluripotent cell culture conditions. Whereas TET1 is abundantly expressed in both naïve and primed pluripotent cells, TET2 expression is restricted to the naïve state. Moreover, TET2 is expressed heterogeneously in embryonic stem cells (ESCs) cultured in serum/leukemia inhibitory factor, with expression correlating with naïve pluripotency markers. FACS-sorting of ESCs carrying a Tet2Flag-IRES-EGFP reporter demonstrated that TET2-negative cells have lost the ability to form undifferentiated ESC colonies. We further show that TET2 binds to the transcription factor NANOG. We hypothesize that TET2 and NANOG co-localise on chromatin to regulate enhancers associated with naïve pluripotency genes.

Introduction Australia has recently implemented major changes in cervical cancer prevention policies including introduction of primary human papillomavirus (HPV) screening starting at age 25, and replacement of the quadrivalent HPV vaccine with the nonavalent vaccine in the national school-based program. We assessed the feasibility and utility of conducting HPV testing in residual clinical specimens submitted for routine Chlamydia trachomatis screening, as a means of tracking HPV vaccine program impact among young sexually active women. Methods De-identified residual specimens from women aged 16–24 years submitted for chlamydia testing were collected from three pathology laboratories in Victoria and New South Wales. Limited demographic information, and chlamydia test results were also collected. Patient identifiers were sent directly from the laboratories to the National HPV Vaccination Program Register, to obtain HPV vaccination histories. Samples underwent HPV genotyping using Seegene Anyplex II HPV 28 assay. Results Between April and July 2018, 362 residual samples were collected, the majority (60.2%) of which were cervical swabs. Demographic data and vaccination histories were received for 357 (98.6%) women (mean age 21.8, SD 2.0). Overall, 65.6% of women were fully vaccinated, 9.8% partially, and 24.7% unvaccinated. The majority (86.0%) resided in a major city, 35.9% were classified in the upper quintile of socioeconomic advantage and chlamydia positivity was 7.8%. The prevalence of quadrivalent vaccine-targeted types (HPV6/11/16/18) was 2.8% (1.5–5.1%) overall with no differences by vaccination status (p = 0.729). The prevalence of additional nonavalent vaccine-targeted types (HPV31/33/45/52/58) was 19.3% (15.6–23.8%). One or more oncogenic HPV types were detected in 46.8% (95% CI 41.6–52.0%) of women. Conclusions HPV testing of residual chlamydia specimens provides a simple, feasible method for monitoring circulating genotypes. Applied on a larger scale this method can be utilised to obtain a timely assessment of nonavalent vaccine impact among young women not yet eligible for cervical screening.

An open and decondensed chromatin organization is a defining property of pluripotency. Several epigenetic regulators have been implicated in maintaining an open chromatin organization, but how these processes are connected to the pluripotency network is unknown. Here, we identified a new role for the transcription factor NANOG as a key regulator connecting the pluripotency network with constitutive heterochromatin organization in mouse embryonic stem cells. Deletion of Nanog leads to chromatin compaction and the remodeling of heterochromatin domains. Forced expression of NANOG in epiblast stem cells is sufficient to decompact chromatin. NANOG associates with satellite repeats within heterochromatin domains, contributing to an architecture characterized by highly dispersed chromatin fibers, low levels of H3K9me3, and high major satellite transcription, and the strong transactivation domain of NANOG is required for this organization. The heterochromatin-associated protein SALL1 is a direct cofactor for NANOG, and loss of Sall1 recapitulates the Nanog-null phenotype, but the loss of Sall1 can be circumvented through direct recruitment of the NANOG transactivation domain to major satellites. These results establish a direct connection between the pluripotency network and chromatin organization and emphasize that maintaining an open heterochromatin architecture is a highly regulated process in embryonic stem cells.

SummaryIt has previously been reported that mouse epiblast stem cell (EpiSC) lines comprise heterogeneous cell populations that are functionally equivalent to cells of either early- or late-stage postimplantation development. So far, the establishment of the embryonic stem cell (ESC) pluripotency gene regulatory network through the widely known chemical inhibition of MEK and GSK3beta has been impractical in late-stage EpiSCs. Here, we show that chemical inhibition of casein kinase 1alpha (CK1alpha) induces the conversion of recalcitrant late-stage EpiSCs into ESC pluripotency. CK1alpha inhibition directly results in the simultaneous activation of the WNT signaling pathway, together with inhibition of the TGFbeta/SMAD2 signaling pathway, mediating the rewiring of the gene regulatory network in favor of an ESC-like state. Our findings uncover a molecular mechanism that links CK1alpha to ESC pluripotency through the direct modulation of WNT and TGFbeta signaling.

Scenario planning and the use of alternative futures have been used successfully to assist organisations, communities and countries to move towards desired outcomes ( Dator, 2009 ). In this study we used a unique combination of scenario planning and a national public opinion survey to explore preferred futures for Australia in 2050. The approach used four future scenarios for Australia in 2050 as the basis for an online national public opinion survey entitled Australia: Our Future, Your Voice. Scenario development was based on a review of a broad range of scenarios for Australia and globally. We then developed four synthesis scenarios based on two axes of individual versus community orientation, and national focus on GDP growth versus a focus on well-being more broadly defined. The scenarios were labelled: (1) Free Enterprise (FE); (2) Strong Individualism (SI); (3) Coordinated Action (CA); and (4) Community Well-being (CW). We created a website that described each of these scenarios and invited people to complete a survey after they had reviewed the scenarios. The survey engaged 2575 adults in two groups: (1) a targeted statistically representative national sample (n = 2083) and (2) a self-selected sample (n = 492). Results from both groups and across all demographic categories revealed that a majority of participants preferred the Community Well-being (CW) scenario. 73% (Representative) and 61% (Self Select) ranked this scenario as 1st or 2nd. We also asked which scenario Australia was headed toward. 32% of the Representative sample and 50% of the Self-Selected sample participants ranked the Free Enterprise (FE) scenario as the most likely future. CW was ranked least likely to be ‘where Australia is heading?’ The dissonance between the future Australians want and where they thought the country is headed has clear policy implications, which we discuss. This extension of scenario planning to include public opinion surveys is novel and this approach can be used to improve thinking, discussion, planning and policy about the future of Australia, as well as potentially other countries and regions.

This article explores the manner in which spatial knowledge affected colonial encounters. Utilizing Bourdieu's concept of habitus, I argue that space, like language, art, and gender, is a cultural construct and that for each individual nation there existed a spatial habitus. This spatial understanding was one lens through which contact was viewed. Using the concept of contrasting spatial habitus, the article seeks to explain the actions, by both European and Cherokee individuals, during the visit to Cherokee space by Sir Alexander Cuming in 1730 and the subsequent return visit of Cuming and seven Cherokee to London. It unpacks the events during Cuming's Atlantic travels showing that both incidents were interpreted differently by each nation through their own spatial habitus. Thereby showing that travelers whether they be British moving to America or Cherokee moving to England carried with them their spatial understandings as clearly as they carried their baggage.

During the 1930s, Shanghai was a major center of Soviet espionage. By 1935 Chinese and Japanese agents of the USSR's military intelligence service, the Razvedyvatel'noe Upravlenie or RU, had successfully penetrated key Guomindang, Japanese, and U.S. targets, providing critical intelligence for Moscow and the Chinese Communist Party (CCP). These accomplishments collapsed after the detention of RU leader Yakov Bronin (commonly known as Joseph Walden) and several of his Chinese associates in May 1935, the culmination of a series of tradecraft errors and misjudgments. As attempts to establish Bronin's nationality foundered, a classic confrontation developed between Chinese authorities seeking Bronin's immediate rendition and those of the International Settlement and French Concession, both determined to uphold the principle of extra-territoriality. Once Bronin's fraudulent claim to French nationality was exposed he was duly extradited and received a 15–year jail sentence for espionage, leaving RU netw...

Deletion ofSox2from embryonic stem cells (ESCs) causes trophectodermal differentiation. While this can be prevented by enforced expression of the related SOXB1 proteins, SOX1 or SOX3, the roles of SOXB1 proteins in epiblast stem cell (EpiSC) pluripotency are unknown. Here we show thatSox2can be deleted from EpiSCs with impunity. This is due to a shift in the balance of SoxB1 expression in EpiSCs, which have decreased Sox2 and increased Sox3 compared to ESCs. Consistent with functional redundancy,Sox3can also be deleted from EpiSCs without eliminating self-renewal. However, deletion of bothSox2andSox3prevents self-renewal. The overall SOXB1 levels in ESCs affect differentiation choices: neural differentiation ofSox2heterozygous ESCs is compromised, while increased SOXB1 levels divert the ESC to EpiSC transition towards neural differentiation. Therefore, optimal SOXB1 levels are critical for each pluripotent state and for cell fate decisions during exit from naïve pluripotency.

Sin3a is the central scaffold protein of the prototypical Hdac1/2 chromatin repressor complex, crucially required during early embryonic development for the growth of pluripotent cells of the inner cell mass. Here, we compare the composition of the Sin3a‐Hdac complex between pluripotent embryonic stem (ES) and differentiated cells by establishing a method that couples two independent endogenous immunoprecipitations with quantitative mass spectrometry. We define the precise composition of the Sin3a complex in multiple cell types and identify the Fam60a subunit as a key defining feature of a variant Sin3a complex present in ES cells, which also contains Ogt and Tet1. Fam60a binds on H3K4me3‐positive promoters in ES cells, together with Ogt, Tet1 and Sin3a, and is essential to maintain the complex on chromatin. Finally, we show that depletion of Fam60a phenocopies the loss of Sin3a, leading to reduced proliferation, an extended G1‐phase and the deregulation of lineage genes. Taken together, Fam60a is an essential core subunit of a variant Sin3a complex in ES cells that is required to promote rapid proliferation and prevent unscheduled differentiation.

Summary Enhancers are genetic elements that regulate spatiotemporal gene expression. Enhancer function requires transcription factor (TF) binding and correlates with histone modifications. However, the extent to which TF binding and histone modifications functionally define active enhancers remains unclear. Here, we combine chromatin immunoprecipitation with a massively parallel reporter assay (ChIP-STARR-seq) to identify functional enhancers in human embryonic stem cells (ESCs) genome-wide in a quantitative unbiased manner. Although active enhancers associate with TFs, only a minority of regions marked by NANOG, OCT4, H3K27ac, and H3K4me1 function as enhancers, with activity markedly changing under naive versus primed culture conditions. We identify an enhancer set associated with functions extending to non-ESC-specific processes. Moreover, although transposable elements associate with putative enhancers, only some exhibit activity. Similarly, within super-enhancers, large tracts are non-functional, with activity restricted to small sub-domains. This catalog of validated enhancers provides a valuable resource for further functional dissection of the regulatory genome., Graphical Abstract, Highlights • Massively parallel reporter assay assessed over 350,000 genome regions • ChIP-STARR-seq catalogs functional enhancers in primed and naive hESCs • Identification of transcription factors and transposable elements linked to enhancers • ChIP-STARR-seq dissects super-enhancers into small functional units, Barakat et al. use a combination of chromatin immunoprecipitation and a massively parallel reporter assay to identify functional enhancers in primed and naive human embryonic stem cells. This genome-wide catalog of validated enhancers provides a valuable resource for the further dissection of the regulatory genome.

Oct4 and Sox2 regulate the expression of target genes such as Nanog, Fgf4, and Utf1, by binding to their respective regulatory motifs. Their functional cooperation is reflected in their ability to heterodimerize on adjacent cis regulatory motifs, the composite Sox/Oct motif. Given that Oct4 and Sox2 regulate many developmental genes, a quantitative analysis of their synergistic action on different Sox/Oct motifs would yield valuable insights into the mechanisms of early embryonic development. In the present study, we measured binding affinities of Oct4 and Sox2 to different Sox/Oct motifs using fluorescence correlation spectroscopy. We found that the synergistic binding interaction is driven mainly by the level of Sox2 in the case of the Fgf4 Sox/Oct motif. Taking into account Sox2 expression levels fluctuate more than Oct4, our finding provides an explanation on how Sox2 controls the segregation of the epiblast and primitive endoderm populations within the inner cell mass of the developing rodent blastocyst.

This article explores the origins and early development of China’s Signals Intelligence (SIGINT) service, using data released officially since the mid-1980s. Born from revolutionary crisis in the late 1920s, the Red Army’s SIGINT service was founded in 1931, an offshoot of the Chinese Communist Party (CCP)’s development of wireless communications. Though the USSR provided some training assistance, the formative early development of the service relied more on indigenous resources: the training of teenage novices in underground facilities in Shanghai and the Central Soviet and the use of equipment that was self-made, illicitly procured or seized on the battlefield. In the years that followed, Red Army SIGINT – much respected by CCP/Red Army leaders – survived defections and cryptographic obstacles to play a major role in the defence of the Central Soviet against Guomindang encirclement. As military defeat became inevitable, SIGINT also helped to facilitate the successful Red Army retreat that became the his...

Tet1, Tet2, and Tet3 encode DNA demethylases that play critical roles during stem cell differentiation and reprogramming to pluripotency. Although all three genes are transcribed in pluripotent cells, little is known about the expression of the corresponding proteins. Here, we tagged all the endogenous Tet family alleles using CRISPR/Cas9, and characterised TET protein expression in distinct pluripotent cell culture conditions. Whereas TET1 is abundantly expressed in both naïve and primed pluripotent cells, TET2 expression is restricted to the naïve state. Moreover, TET2 is expressed heterogeneously in embryonic stem cells (ESCs) cultured in serum/leukemia inhibitory factor, with expression correlating with naïve pluripotency markers. FACS-sorting of ESCs carrying a Tet2Flag-IRES-EGFP reporter demonstrated that TET2-negative cells have lost the ability to form undifferentiated ESC colonies. We further show that TET2 binds to the transcription factor NANOG. We hypothesize that TET2 and NANOG co-localise on chromatin to regulate enhancers associated with naïve pluripotency genes.

Pluripotency is a property that early embryonic cells possess over a considerable developmental time span. Accordingly, pluripotent cell lines can be established from the pre-implantation or post-implantation mouse embryo as embryonic stem (ES) or epiblast stem (EpiSC) cell lines, respectively. Maintenance of the pluripotent phenotype depends on the function of specific transcription factors (TFs) operating within a pluripotency gene regulatory network (PGRN). As cells move from an ES cell to an EpiSC state, the PGRN changes with expression of some TFs reduced (e.g. Nanog) or eliminated (e.g. Esrrb). Re-expressing such TFs can move cells back to an earlier developmental identity and is being applied to attempt establishment of human cell lines with the properties of mouse ES cells.