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In vitro cultured stem cells with distinct developmental capacities can contribute to embryonic or extraembryonic tissues after microinjection into pre-implantation mammalian embryos. However, whether cultured stem cells can independently give rise to entire gastrulating embryo-like structures with embryonic and extraembryonic compartments remains unknown. Here, we adapt a recently established platform for prolonged ex utero growth of natural embryos to generate mouse post-gastrulation synthetic whole embryo models (sEmbryos), with both embryonic and extraembryonic compartments, starting solely from naive ESCs. This was achieved by co-aggregating non-transduced ESCs, with naive ESCs transiently expressing Cdx2 or Gata4 to promote their priming toward trophectoderm and primitive endoderm lineages, respectively. sEmbryos adequately accomplish gastrulation, advance through key developmental milestones, and develop organ progenitors within complex extraembryonic compartments similar to E8.5 stage mouse embryos. Our findings highlight the plastic potential of naive pluripotent cells to self-organize and functionally reconstitute and model the entire mammalian embryo beyond gastrulation.

The fidelity of the early embryonic program is underlined by tight regulation of the chromatin. Yet, how the chromatin is organized to prohibit the reversal of the developmental program remains unclear. Specifically, the totipotency-to-pluripotency transition marks one of the most dramatic events to the chromatin, and yet, the nature of histone alterations underlying this process is incompletely characterized. Here, we show that linker histone H1 is post-translationally modulated by SUMO2/3, which facilitates its fixation onto ultra-condensed heterochromatin in embryonic stem cells (ESCs). Upon SUMOylation depletion, the chromatin becomes de-compacted and H1 is evicted, leading to totipotency reactivation. Furthermore, we show that H1 and SUMO2/3 jointly mediate the repression of totipotent elements. Lastly, we demonstrate that preventing SUMOylation on H1 abrogates its ability to repress the totipotency program in ESCs. Collectively, our findings unravel a critical role for SUMOylation of H1 in facilitating chromatin repression and desolation of the totipotent identity.

The mammalian body plan is established shortly after the embryo implants into the maternal uterus, and our understanding of post-implantation developmental processes remains limited. Although pre- and peri-implantation mouse embryos are routinely cultured in vitro1,2, approaches for the robust culture of post-implantation embryos from egg cylinder stages until advanced organogenesis remain to be established. Here we present highly effective platforms for the ex utero culture of post-implantation mouse embryos, which enable the appropriate development of embryos from before gastrulation (embryonic day (E) 5.5) until the hindlimb formation stage (E11). Late gastrulating embryos (E7.5) are grown in three-dimensional rotating bottles, whereas extended culture from pre-gastrulation stages (E5.5 or E6.5) requires a combination of static and rotating bottle culture platforms. Histological, molecular and single-cell RNA sequencing analyses confirm that the ex utero cultured embryos recapitulate in utero development precisely. This culture system is amenable to the introduction of a variety of embryonic perturbations and micro-manipulations, the results of which can be followed ex utero for up to six days. The establishment of a system for robustly growing normal mouse embryos ex utero from pre-gastrulation to advanced organogenesis represents a valuable tool for investigating embryogenesis, as it eliminates the uterine barrier and allows researchers to mechanistically interrogate post-implantation morphogenesis and artificial embryogenesis in mammals. A new culture system makes it possible to grow mouse embryos and study their development outside the uterus up to the point of late organogenesis.

Summary Isolating human MEK/ERK signaling-independent pluripotent stem cells (PSCs) with naive pluripotency characteristics while maintaining differentiation competence and (epi)genetic integrity remains challenging. Here, we engineer reporter systems that allow the screening for defined conditions that induce molecular and functional features of human naive pluripotency. Synergistic inhibition of WNT/β-CATENIN, protein kinase C (PKC), and SRC signaling consolidates the induction of teratoma-competent naive human PSCs, with the capacity to differentiate into trophoblast stem cells (TSCs) and extraembryonic naive endodermal (nEND) cells in vitro. Divergent signaling and transcriptional requirements for boosting naive pluripotency were found between mouse and human. P53 depletion in naive hPSCs increased their contribution to mouse-human cross-species chimeric embryos upon priming and differentiation. Finally, MEK/ERK inhibition can be substituted with the inhibition of NOTCH/RBPj, which induces alternative naive-like hPSCs with a diminished risk for deleterious global DNA hypomethylation. Our findings set a framework for defining the signaling foundations of human naive pluripotency., Graphical abstract, Highlights • Inhibition of SRC, PKC, and WNT consolidates human naive pluripotency induction • Competitiveness of p53 depleted human PSCs in cross-species chimeric embryos • Opposing net effect for ACTIVIN and WNT on mouse versus human naive pluripotency • 2i and ERKi independent alternative human naive-like PSC conditions, Engineered systems were used to screen for conditions that enable robust induction of human naive PSCs without the obligation for exogenous transgenes or feeder cells. The latter allowed defining the signaling and transcriptional foundations of human naive PSCs with enhanced (epi)genetic stability and competence for differentiation into all lineages.

Different conditions have been devised to isolate MEK/ERK signalling independent human naïve pluripotent stem cells (PSCs) that are distinct from conventional primed PSCs and better correspond to pre-implantation developmental stages. While the naïve conditions described thus far endow human PSCs with different extents of naivety features, isolating human pluripotent cells that retain characteristics of ground state pluripotency while maintaining differentiation potential and genetic integrity, remains a major challenge. Here we engineer reporter systems that allow functional screening for conditions that can endow both the molecular and functional features expected from human naive pluripotency. We establish that simultaneous inhibition of SRC-NFκB, WNT/ßCATENIN and PKC signalling pathways is essential for enabling expansion of teratoma competent fully naïve human PSCs in defined or xeno-free conditions. Divergent signalling and transcriptional requirements for maintaining naïve pluripotency were found between mouse and human. Finally, we establish alternative naïve conditions in which MEK/ERK inhibition is substituted with inhibition for NOTCH/RBPj signalling, which allow obtaining alternative human naïve PSCs with diminished risk for loss of imprinting and deleterious global DNA hypomethylation. Our findings set a framework for the signalling foundations of human naïve pluripotency and may advance its utilization in future translational applications.Highlights of key findingsCombined inhibition of SRC, WNT and PKC signaling consolidates human naïve pluripotencyStable expansion of DNA/RNA methylation-independent and TGF/ACTIVIN-independent human naïve PSCsOpposing roles for ACTIVIN and WNT/ßCATENIN signaling on mouse vs. human naive pluripotency2i and MEK/ERKi independent alternative human naïve PSC conditions via inhibiting NOTCH/RBPj signaling

BMAP-27 and melittin are two antimicrobial peptides (AMPs) that display potent antimicrobial activities against a wide range of microbes including multidrug resistant (MDR) strains of bacteria. Unfortunately, their significant toxicity against eukaryotic cells has hampered their development into clinically useful antibiotics. In this study, we have rationally designed a novel hybrid AMP aiming to retain the potent antimicrobial activities of BMAP-27 and melittin while enhancing their therapeutic index. The strategy employed in our design was based on combining the activities of individual α-helical fragments of each AMP to generate a novel hybrid AMP with improved characteristics compared to the parent peptides. Named as BMAP27-Melittin, the novel peptide displayed broad spectrum antimicrobial activity against standard representative Gram-positive and Gram-negative bacterial strains in the range of 1–7.5 µM. Moreover, the peptide managed to kill standard resistant strains of MDR bacteria with significant potency and with MIC values as low as 1 µM. BMAP27-Melittin also proved to exhibit potent antibiofilm activities while the hemolytic and antiproliferative studies against eukaryotic cells revealed that the peptide is exhibiting minimal toxicity at antimicrobial concentrations. Additionally, the molecular dynamics simulations of the peptide folding displayed that the hybrid peptide has folded into a well-defined α-helical structure; supporting the experimental findings. Overall, this work highlights the potential of rational design in generating improved AMPs with enhanced specificity that could be developed into successful therapeutics for the treatment of bacterial infections.

Many pathogenic free living and biofilm forming bacterial organisms can cause serious infections to humans that could consequently have devastating effects on human health. A significant number of these microbial organisms are resistant to almost all known conventional antibiotics and the ability of some these strains to form sessile communities of biofilms increases the resistance ability of bacteria to antibiotic treatment. Global research is currently focused on finding novel therapies to counteract the threat of bacterial and biofilm infections rather than using conventional antibiotics. Mauriporin, a novel cationic a-helical peptide identified from the venom derived cDNA library of the scorpion Androctonus mauritanicus was reported to display selec- tive cytotoxic and anti-proliferative activity against pros- tate cancer cell lines. In the present study, we investigated the antimicrobial and antibiofilm activities of Mauriporin. Our results show that Mauriporin displays potent antimi- crobial activities against a range of Gram-positive and Gram-negative planktonic bacteria with MIC values in the range 5 l Mt o 10lM. Mauriporin was also able to pre- vent Pseudomonas aeruginosa biofilm formation while showing weak hemolytic activity towards human eryth- rocytes. Studies on the mechanism of action of Mau- riporin revealed that the peptide is probably inducing bacterial cell death through membrane permeabilization determined by the release of b-galactosidase enzyme from peptide treated Escherichia coli cells. Moreover, DNA binding studies found that Mauriporin can cause potent binding to intracellular DNA. All these results indicate that Mauriporin has a considerable potential for thera- peutic application as a novel drug candidate for eradi- cating bacterial infections.

Ammar Almaaytah,1 Ya’u Ajingi,2 Ahmad Abualhaijaa,2 Shadi Tarazi,2 Nizar Alshar’i,3 Qosay Al-Balas3 1Department of Pharmaceutical Technology, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan; 2Department of Applied Biological Sciences, Faculty of Science and Arts, Jordan University of Science and Technology, Irbid, Jordan; 3Department of Medicinal Chemistry, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan Abstract: The rise of multidrug-resistant bacteria is causing a serious threat to the world’s human population. Recent reports have identified bacterial strains displaying pan drug resistance against antibiotics and generating fears among medical health specialists that humanity is on the dawn of entering a post-antibiotics era. Global research is currently focused on expanding the lifetime of current antibiotics and the development of new antimicrobial agents to tackle the problem of antimicrobial resistance. In the present study, we designed a novel consensus peptide named “Pepcon” through peptide consensus sequence determination among members of a highly homologous group of scorpion antimicrobial peptides. Members of this group were found to possess moderate antimicrobial activity with significant toxicity against mammalian cells. The aim of our design method was to generate a novel peptide with an enhanced antimicrobial potency and selectivity against microbial rather than mammalian cells. The results of our study revealed that the consensus peptide displayed potent antibacterial activities against a broad range of Gram-positive and Gram-negative bacteria. Our membrane permeation studies displayed that the peptide efficiently induced membrane damage and consequently led to cell death through the process of cell lysis. The microbial DNA binding assay of the peptide was found to be very weak suggesting that the peptide is not targeting the microbial DNA. Pepcon induced minimal cytotoxicity at the antimicrobial concentrations as the hemolytic activity was found to be zero at the minimal inhibitory concentrations (MICs). The results of our study demonstrate that the consensus peptide design strategy is efficient in generating peptides. Keywords: peptide, scorpion, venom, peptide design, antimicrobial peptides, consensus sequence

Prostate cancer is the second most common cancer in men and the second leading cause of cancer-related deaths among men in the western world. Finding a cure for prostate cancer is urgently needed. Scorpion venoms are rich sources of biologically active peptides, among which the non-disulfide bridged peptides constitute an important group displaying multifunctional activities. The non-disulfide bridged scorpion venom peptides are rarely identified and poorly characterized so far. In this work, we report the molecular cloning and functional characterization of a novel non-disulfide bridged peptide from the venomous gland cDNA library of the Moroccan scorpion Androctonus mauritanicus. Named Mauriporin, the peptide was found to be composed of 48 residues and circular dichroism analysis revealed the peptide to display a well defined α-helical structure in membrane mimicking environments. A synthetic replicate of Mauriporin was found to exert potent selective cytotoxic and antiproliferative activity against prostate cancer cell lines (IC50 4.4–7.8 μM) when compared with non-tumorigenic cells. In this concentration range, Mauriporin produced also negligible degrees of hemolytic activities against mammalian erythrocytes. Apoptotic studies displayed that Mauriporin is not causing cell death through an apoptotic-mediated pathway but possibly through a necrotic mode of cell death. In conclusion Mauriporin may offer a novel therapeutic strategy in the treatment of prostate cancer considering its significant cytotoxic potency against prostate cancer cells and low toxicity to non-tumorigenic cells.

The high level of reported multidrug resistant pathogens with the failure of most conventional antibiotic to kill many of them arise the global concern in the last decade to find alternatives urgently. Many researches are conducted on scorpion venom area and different antimicrobial peptides had been reported in literature also  many had been functionally characterized in the last decade. Here quick overview of all scorpion AMPs with antibacterial activity , their Structural determinants, classification types and their mode of action, in addition to their resistance mechanism and finally their therapeutics potential

The recent derivation of human trophoblast stem cells (TSCs) from placental cytotrophoblasts and blastocysts opened opportunities for studying the development and function of the human placenta. Recent reports have suggested that human naïve, but not primed, pluripotent stem cells (PSCs) retain an exclusive potential to generate TSCs. Here we report that, in the absence of WNT stimulation, transforming growth factor β (TGF-β) pathway inhibition leads to direct and robust conversion of primed human PSCs into TSCs. The resulting primed PSC-derived TSC lines exhibit self-renewal, can differentiate into the main trophoblast lineages, and present RNA and epigenetic profiles that are indistinguishable from recently established TSC lines derived from human placenta, blastocysts, or isogenic human naïve PSCs expanded under human enhanced naïve stem cell medium (HENSM) conditions. Activation of nuclear Yes-associated protein (YAP) signaling is sufficient for this conversion and necessary for human TSC maintenance. Our findings underscore a residual plasticity in primed human PSCs that allows their in vitro conversion into extra-embryonic trophoblast lineages.