Complications in modern hysteroscopic myomectomy

Uterine fibroids (UFs) are common benign tumors of the female genital tract, diagnosed in almost one-quarter of women of reproductive age. UFs may cause numerous clinical symptoms, including prolonged or heavy menstrual bleeding, pelvic pressure symptoms, pain, infertility and others. Submucous fibroids arise from the muscular part of the uterus and pen­etrate into the uterine cavity. They are mostly managed with the use of hysteroscopic myomectomy (HM), which provides direct visualization from the transcervical approach. The sheer number of HM standards and techniques is reason enough to review the available literature about HM-related complications. HM is a safe and effective treatment in patients with the normal size of the uterus and with no more than a few UFs. The procedure should not be initiated without adequate preparation and diagnosis, using the best methods available

miR-125b-5p impacts extracellular vesicle biogenesis, trafficking, and EV subpopulation release in the porcine trophoblast by regulating ESCRT-dependent pathway

Abstract Intercellular communication is a critical process that ensures cooperation between distinct cell types at the embryo–maternal interface. Extracellular vesicles (EVs) are considered to be potent mediators of this communication by transferring biological information in their cargo (e.g., miRNAs) to the recipient cells. miRNAs are small non-coding RNAs that affect the function and fate of neighboring and distant cells by regulating gene expression. Focusing on the maternal side of the dialog, we recently revealed the impact of embryonic signals, including miRNAs, on EV-mediated cell-to-cell communication. In this study, we show the regulatory mechanism of the miR-125b-5p ESCRT-mediated EV biogenesis pathway and the further secretion of EVs by trophoblasts at the time when the crucial steps of implantation are taking place. To test the ability of miR-125b-5p to influence the expression of genes involved in the generation and release of EV subpopulations in porcine conceptuses, we used an ex vivo approach. Next, in silico and in vitro analyses were performed to confirm miRNA–mRNA interactions. Finally, EV trafficking and release were assessed using several imaging and particle analysis tools. Our results indicated that conceptus development and implantation are accompanied by changes in the abundance of EV biogenesis and trafficking machinery. ESCRT-dependent EV biogenesis and the further secretion of EVs were modulated by miR-125b-5p, specifically impacting the ESCRT-II complex (via VPS36) and EV trafficking in primary porcine trophoblast cells. The identified miRNA–ESCRT interplay led to the generation and secretion of specific subpopulations of EVs. miRNA present at the embryo–maternal interface governs EV-mediated communication between the mother and the developing conceptus, leading to the generation, trafficking, and release of characteristic subpopulations of EVs

High-resolution cryo-EM structures of plant cytochrome b6fb_{6}f at work

Plants use solar energy to power cellular metabolism. The oxidation of plastoquinol and reduction of plastocyanin by cytochrome $b_{6}f$ (Cyt $b_{6}f$) is known as one of the key steps of photosynthesis, but the catalytic mechanism in the plastoquinone oxidation site ($Q_{p}$) remains elusive. Here, we describe two high-resolution cryo-EM structures of the spinach Cyt $b_{6}f$ homodimer with endogenous plastoquinones and in complex with plastocyanin. Three plastoquinones are visible and line up one after another head to tail near $Q_{p}$ in both monomers, indicating the existence of a channel in each monomer. Therefore, quinones appear to flow through Cyt $b_{6}f$ in one direction, transiently exposing the redox-active ring of quinone during catalysis. Our work proposes an unprecedented one-way traffic model that explains efficient quinol oxidation during photosynthesis and respiration. Structures of cytochrome $b_{6}f$ with and without plastocyanin imply a one-way traffic of quinones for efficient photosynthesis

Structural basis of transposon end recognition explains central features of Tn7 transposition systems

Tn7 is a bacterial transposon with relatives containing element-encoded CRISPR-Cas systems mediating RNA-guided transposon insertion. Here, we present the 2.7 Å cryoelectron microscopy structure of prototypic Tn7 transposase TnsB interacting with the transposon end DNA. When TnsB interacts across repeating binding sites, it adopts a beads-on-a-string architecture, where the DNA-binding and catalytic domains are arranged in a tiled and intertwined fashion. The DNA-binding domains form few base-specific contacts leading to a binding preference that requires multiple weakly conserved sites at the appropriate spacing to achieve DNA sequence specificity. TnsB binding imparts differences in the global structure of the protein-bound DNA ends dictated by the spacing or overlap of binding sites explaining functional differences in the left and right ends of the element. We propose a model of the strand-transfer complex in which the terminal TnsB molecule is rearranged so that its catalytic domain is in a position conducive to transposition

Cryo-EM structures of the human Elongator complex at work

tRNA modifications affect ribosomal elongation speed and co-translational folding dynamics. The Elongator complex is responsible for introducing 5-carboxymethyl at wobble uridine bases (cm5U34) in eukaryotic tRNAs. However, the structure and function of human Elongator remain poorly understood. In this study, we present a series of cryo-EM structures of human ELP123 in complex with tRNA and cofactors at four different stages of the reaction. The structures at resolutions of up to 2.9 Å together with complementary functional analyses reveal the molecular mechanism of the modification reaction. Our results show that tRNA binding exposes a universally conserved uridine at position 33 (U33), which triggers acetyl-CoA hydrolysis. We identify a series of conserved residues that are crucial for the radical-based acetylation of U34 and profile the molecular effects of patient-derived mutations. Together, we provide the high-resolution view of human Elongator and reveal its detailed mechanism of action

Cryo-EM structure of the fully assembled elongator complex

Transfer RNA (tRNA) molecules are essential to decode messenger RNA codons during protein synthesis. All known tRNAs are heavily modified at multiple positions through post-transcriptional addition of chemical groups. Modifications in the tRNA anticodons are directly influencing ribosome decoding and dynamics during translation elongation and are crucial for maintaining proteome integrity. In eukaryotes, wobble uridines are modified by Elongator, a large and highly conserved macromolecular complex. Elongator consists of two subcomplexes, namely Elp123 containing the enzymatically active Elp3 subunit and the associated Elp456 hetero-hexamer. The structure of the fully assembled complex and the function of the Elp456 subcomplex have remained elusive. Here, we show the cryo-electron microscopy structure of yeast Elongator at an overall resolution of 4.3 Å. We validate the obtained structure by complementary mutational analyses in vitro and in vivo. In addition, we determined various structures of the murine Elongator complex, including the fully assembled mouse Elongator complex at 5.9 Å resolution. Our results confirm the structural conservation of Elongator and its intermediates among eukaryotes. Furthermore, we complement our analyses with the biochemical characterization of the assembled human Elongator. Our results provide the molecular basis for the assembly of Elongator and its tRNA modification activity in eukaryotes

SOLARIS National Synchrotron Radiation Centre in Krakow, Poland

The SOLARIS synchrotron located in Krakow, Poland, is a third-generation light source operating at medium electron energy. The first synchrotron light was observed in 2015, and the consequent development of infrastructure lead to the first users’ experiments at soft X-ray energies in 2018. Presently, SOLARIS expands its operation towards hard X-rays with continuous developments of the beamlines and concurrent infrastructure. In the following, we will summarize the SOLARIS synchrotron design, and describe the beamlines and research infrastructure together with the main performance parameters, upgrade, and development plans