Structure and Function of a Bacterial Gap Junction Analog.

Multicellular lifestyle requires cell-cell connections. In multicellular cyanobacteria, septal junctions enable molecular exchange between sister cells and are required for cellular differentiation. The structure of septal junctions is poorly understood, and it is unknown whether they are capable of controlling intercellular communication. Here, we resolved the in situ architecture of septal junctions by electron cryotomography of cryo-focused ion beam-milled cyanobacterial filaments. Septal junctions consisted of a tube traversing the septal peptidoglycan. Each tube end comprised a FraD-containing plug, which was covered by a cytoplasmic cap. Fluorescence recovery after photobleaching showed that intercellular communication was blocked upon stress. Gating was accompanied by a reversible conformational change of the septal junction cap. We provide the mechanistic framework for a cell junction that predates eukaryotic gap junctions by a billion years. The conservation of a gated dynamic mechanism across different domains of life emphasizes the importance of controlling molecular exchange in multicellular organisms.

Coupling Titanium and Chromium Catalysis in a Reaction Network for the Reprogramming of [BH4 ]- as Electron Transfer and Hydrogen Atom Transfer Reagent for Radical Chemistry.

We describe a unique catalytic system with an efficient coupling of Ti- and Cr-catalysis in a reaction network that allows the use of [BH4 ]- as stoichiometric hydrogen atom and electron donor in catalytic radical chemistry. The key feature is a relay hydrogen atom transfer from [BH4 ]- to Cr generating the active catalysts under mild conditions. This enables epoxide reductions, regiodivergent epoxide opening and radical cyclizations that are not possible with cooperative catalysis with radicals or by epoxide reductions via Meinwald rearrangement and ensuing carbonyl reduction. No typical SN 2-type reactivity of [BH4 ]- salts is observed.

Effect of probiotics on vaginal Ureaplasma parvum in women suffering from unexplained infertility.

RESEARCH QUESTION: Does oral probiotic supplementation influence the relative abundance of different vaginal microbiota in women experiencing infertility? DESIGN: A prospective, monocentric randomized controlled trial. To study the influence of probiotics on infertility, 80 patients with primary or secondary infertility were included. Patients were assigned to either a probiotic treatment or a control group. Participants in the treatment group (n = 40) took one sachet (2 g) a day of a defined probiotic supplement limiting Lactobacillus strains. Patients in the control group did not receive any additional probiotic supplements. Vaginal samples were taken on day 20 of the menstrual cycle and 4 weeks later, on day 20, of the consecutive cycle. Subsequently, 16s rRNA gene analysis of the vaginal samples was conducted. RESULTS: After the intervention phase, no effects on alpha diversity resulting from treatment could be observed. The between sample diversity of different women (beta diversity) at baseline had no effects of age, treatment group or body mass index. Primary or secondary sterility, however, had a significant effect on community. Three clusters (Lactobacillus crispatus, Lactobacillus iners and Lactobacillus gasseri) were identified as the leading representatives. Furthermore, patients treated with probiotics showed limited growth of Ureaplasma parvum compared with the control group (P = 0.021). CONCLUSIONS: This study points to a possible protective effect of probiotic supplements on the vaginal microbiota. It is tempting to speculate that this effect assists in containing the growth of non-beneficial bacteria and helps to prevent or cure a dysbiotic vaginal flora.

Impact of polar body biopsy on embryo morphokinetics-back to the roots in preimplantation genetic testing?

PURPOSE: Polar body biopsy (PBB) is a common technique in preimplantation genetic testing (PGT) to assess the chromosomal status of the oocyte. Numerous studies have been implemented to investigate the impact of biopsies on embryo development; however, information on embryo morphokinetics is still lacking. Hence, we investigated the impact of PBB on morphokinetic parameters in early embryo development. METHODS: Four hundred four embryos (202 PBB, 202 control) were retrospectively analyzed. Patients were stimulated with a gonadotropin-releasing hormone antagonist ovarian hyperstimulation protocol. After fertilization check, embryos were incubated in a time-lapse incubator. The groups were matched for maternal age at time of oocyte retrieval. RESULTS: Mean group times for reaching specific developmental time points showed no significant difference comparing embryos with PBB conducted and without. Likewise, further subdivision of the PBB group in euploid and aneuploid embryos revealed no differences in the early embryo morphokinetic development compared to the control group. Aneuploidy testing revealed a high prevalence of chromosomal aberrations for chromosomes 21, 4, 16, and 19. CONCLUSIONS: In conclusion, PBB does not impact the morphokinetic parameters of the embryo development. PBB can be safely applied without the risk of impairing the reproductive potential of the embryo and can be highly recommended as safe and practicable PGT approach, especially in countries with prevailing restrictions regarding PGT analysis.

Extravillous trophoblasts invade more than uterine arteries: evidence for the invasion of uterine veins.

During the first trimester of pregnancy, extravillous trophoblasts (EVTs) invade into the decidual interstitium to the first third of the myometrium, thereby anchoring the placenta to the uterus. They also follow the endovascular and endoglandular route of invasion; plug, line and remodel spiral arteries, thus being responsible for the establishment of hemotrophic nutrition with the beginning of the second trimester and invade and open uterine glands toward the intervillous space for a histiotrophic nutrition during the first trimester. The aim of this study was to provide proof that uterine veins are invaded by EVTs similar to uterine arteries and glands in first trimester of pregnancy. Therefore, serial sections from in situ first trimester placenta were immuno-single- and immuno-double-stained to distinguish in a first step between arteries and veins and secondly between invaded and non-invaded vessels. Subsequently, invasion of EVTs into uterine vessels was quantified. Our data show that uterine veins are significantly more invaded by EVTs than uterine arteries (29.2 ± 15.7 %) during early pregnancy. Counted vessel cross sections revealed significantly higher EVT invasion into veins (59.5 ± 7.9 %) compared to arteries (29.2 ± 15.7 %). In the lumen of veins, single EVTs were repeatedly found, beside detached glandular epithelial cells or syncytial fragments. This study allows the expansion of our hitherto postulated concept of EVT invasion during first trimester of pregnancy. We suggest that invasion of EVTs into uterine veins is responsible the draining of waste and blood plasma from the intervillous space during the first trimester of pregnancy.

Biobanking of different body fluids within the frame of IVF-a standard operating procedure to improve reproductive biology research.

PURPOSE: The aim of the present study was to develop a standard operating procedure (SOP) for the collection, transport, and storage of human cumulus cells, follicular fluid, blood serum, seminal plasma, embryo culture supernatant, and embryo culture supernatant control obtained within the IVF process under approved protocols and written informed consent from participating patients. The SOP was developed at the Kinderwunsch Institut Schenk, Dobl, Austria, together with Biobank Graz of the Medical University of Graz, Austria. METHODS: The SOP provides comprehensive details of laboratory procedures and sampling of the different fluids within the IVF process. Furthermore, information on sample coding, references of involved laboratory techniques (e.g., oocyte retrieval with a Steiner-TAN needle), ethical approvals, and biobanking procedures are presented. RESULTS: The result of the present study is a standard operating procedure. CONCLUSIONS: The SOP ensures a professional way for collection and scientific use of IVF samples by the Kinderwunsch Institut Schenk, Dobl, Austria, and Biobank Graz of the Medical University of Graz, Austria. It can be used as a template for other institutions to unify specimen collection procedures in the field of reproductive health research.

Anti-Mullerian hormone concentrations in individual follicular fluids within one stimulated IVF cycle resemble blood serum values.

PURPOSE: Anti-Mullerian hormone (AMH) is commonly known as the most potent marker for ovarian reserve due to its decline as female age increases. While serum AMH (sAMH) levels have been intensively investigated, there is less data regarding AMH concentrations in follicular fluid (FF), since FF has usually been designated as waste product during oocyte collection in assisted reproductive technologies. This pilot study investigated follicle AMH concentrations (fAMH) of several follicles per ovary, individually collected with the Steiner-Tan needle, and compared them to sAMH concentrations in women undergoing IVF treatment. We hypothesized that there is no difference of fAMH concentrations in individual follicles and that these concentrations resemble the sAMH value of the patient. METHODS: Patients were stimulated with a gonadotropin-releasing hormone antagonist ovarian hyperstimulation protocol. On the day of oocyte retrieval, serum samples and FF from all individual follicles from one stimulated IVF cycle were collected and individually analyzed for AMH concentrations. RESULTS: Intracyclic mean fAMH values (n follicle = 2-14) were significantly correlated to sAHM values (ρ = 0.85, p < 0.001) and showed a trend to be negatively associated with age (ρ = -0.43, p = 0.06). Mean intrapatient fAMH concentrations differed significantly (p < 0.001). Furthermore, significant correlations of sAMH with individual fAMH values of the first five follicles of each patient were observed. CONCLUSIONS: In conclusion, our results clearly showed that individual fAMH concentrations reflected sAMH values and that fAMH concentrations did not significantly differ within one patient. In future studies, it will be interesting to correlate individual fAMH values to the respective embryo development and overall pregnancy outcome in order to improve IVF treatments and to refrain from embryo overproduction.

The trophoblast plug during early pregnancy: a deeper insight.

During the first trimester of pregnancy, foetal endovascular trophoblasts invade into maternal spiral arteries, accumulate and form plugs in the lumen of the vessels. These plugs only allow blood plasma to seep through. Hence, during the first trimester of pregnancy, a first flow of fluids through the placental intervillous space is established, resulting in a physiological oxygen gradient between mother and foetus. The trophoblast plugs block spiral arteries until the beginning of the second trimester (11-14 weeks). In parallel, uterine glands are invaded and opened by endoglandular trophoblasts towards the intervillous space of the placenta, without showing the formation of plugs (Moser et al. in Hum Reprod 25:1127-1136, 2010, Hum Reprod Oxf Engl 30:2747-2757, 2015). This enables histiotrophic nutrition of the embryo prior to onset of maternal blood flow into the placenta. Failure of these endovascular and endoglandular invasion processes may lead to miscarriage or pregnancy disorders such as intrauterine growth restriction (IUGR). After dissolution of the plugs, the onset of maternal blood flow allows maternal blood cells to enter the intervillous space and oxygen concentrations rise up. In this study, we demonstrate for the first time serial cross sections through a trophoblast plug in a first trimester placental bed specimen. Invaded and plugged arteries as well as invaded uterine glands in week 11 of gestation are visualized with specific immunohistochemical double staining techniques. We show that spiral artery plugs appear throughout the placental invasion zone and illustrate erythrocytes stowed due to trophoblast plugs. In addition, we give evidence of the presence of MMP-1 in plugs of invaded spiral arteries. The results reveal a better understanding and a closer insight into the morphological appearance of trophoblast plugs and the consequences for placental and uterine blood flow.

Placental fractalkine is up-regulated in severe early-onset preeclampsia.

The pathogenesis of preeclampsia (PE) includes the release of placental factors into the maternal circulation, inducing an inflammatory environment in the mother. One of the factors may be the proinflammatory chemokine fractalkine, which is expressed in the syncytiotrophoblast of human placenta, from where it is released into the maternal circulation by constitutive shedding. We examined whether placental fractalkine is up-regulated in severe early-onset PE and whether the proinflammatory cytokines tumor necrosis factor (TNF)-α and IL-6 are able to increase the expression of fractalkine. Gene expression analysis, enzyme-linked immunosorbent assay, and immunohistochemistry consistently showed increased fractalkine expression in placentas from severe early-onset PE, compared to gestational age-matched controls. Expression of a disintegrin and metalloproteinases (ADAMs) 10 and 17, which convert transmembrane fractalkine into the soluble form, was significantly increased in these cases. Incubation of first-trimester placental explants with TNF-α provoked a significant increase in fractalkine expression and release of the soluble form, whereas IL-6 had no effect. TNF-α-mediated up-regulation of placental fractalkine was reversed in the presence of the aspirin-derivative salicylate, which impaired activation of NF-κB p65 in TNF-α-treated explants. On the basis of data from placental explants, we suggest that increased maternal TNF-α may up-regulate the expression and release of placental fractalkine, which, in turn, may contribute to an exaggerated systemic inflammatory response in PE.

Stepwise assembly and release of Tc toxins from Yersinia entomophaga.

Tc toxins are virulence factors of bacterial pathogens. Although their structure and intoxication mechanism are well understood, it remains elusive where this large macromolecular complex is assembled and how it is released. Here we show by an integrative multiscale imaging approach that Yersinia entomophaga Tc (YenTc) toxin components are expressed only in a subpopulation of cells that are 'primed' with several other potential virulence factors, including filaments of the protease M66/StcE. A phage-like lysis cassette is required for YenTc release; however, before resulting in complete cell lysis, the lysis cassette generates intermediate 'ghost' cells, which may serve as assembly compartments and become packed with assembled YenTc holotoxins. We hypothesize that this stepwise mechanism evolved to minimize the number of cells that need to be killed. The occurrence of similar lysis cassettes in diverse organisms indicates a conserved mechanism for Tc toxin release that may apply to other extracellular macromolecular machines.

Detection of antibodies to SARS-CoV-2 after vaccination in seminal plasma and their association to sperm parameters.

There is a public concern that COVID-19 vaccination and SARS-CoV-2 antibodies (Abs) negatively affect male fertility. However, the evidence for the presence of SARS-CoV-2 Abs in seminal plasma (SP) is lacking. We examined whether Abs were detectable in SP after COVID-19 vaccination in 86 men using a direct Ab measurement and by quantification of their neutralizing activity. The results show the presence of SARS-CoV-2 Abs in SP, with a strong correlation to the serum Abs, increasing with the number of vaccinations. Furthermore, the Ab titers are correlating with the neutralization activity. The SARS-CoV-2 vaccination parameters showed no association with the markers of sperm quality. In conclusion, this study indicates substantial levels of Abs in SP after COVID-19 vaccination that correlate with serum Ab titers but do not associate with sperm quality.

Antibodies to SARS-CoV-2 in follicular fluids and their association with assisted reproduction.

Introduction: Every second woman suffering from infertility asks for medical help. There is public concern that vaccination-induced antibodies (Ab) are negatively associated with fertility. A recent study has demonstrated an association between SARS-CoV-2 vaccination and a lower pregnancy rate in the subsequent 60 days. Consequently, Ab could affect fertility success in assisted reproduction. Methods: To address this question, we compared fertilization outcomes of vaccinated (n=35) and nonvaccinated (n=34) women. Paired serum samples and multiple follicular fluids (FF) (up to 10 from the same donor) were collected during the course of assisted reproduction and characterized for oocyte quality, the presence of Ab and trace element concentrations. Results: The results showed a positive correlation of vaccination-induced neutralizing activity of SARS-CoV-2-Ab in serum and FF. On average, Ab concentrations in serum were higher than in the corresponding FF. However, wide variations in SARS-CoV-2 Ab titers were observed between different FF, correlating to trace element levels, even when retrieved from the same donor. Discussion: Overall, FF contents are highly variable, but no negative association was observed between Ab in serum or FF and fertilization success and oocyte development, supporting the safety of SARS-CoV-2 vaccination during assisted reproduction.

Confirmation of human ovulation in assisted reproduction using an adhesive axillary thermometer (femSense®).

Objective: Timing for sexual intercourse is important in achieving pregnancy in natural menstrual cycles. Different methods of detecting the fertile window have been invented, among them luteinization hormone (LH) to predict ovulation and biphasic body basal temperature (BBT) to confirm ovulation retrospectively. The gold standard to detect ovulation in gynecology practice remains transvaginal ultrasonography in combination with serum progesterone. In this study we evaluated a wearable temperature sensing patch (femSense®) using continuous body temperature measurement to confirm ovulation and determine the end of the fertile window. Methods: 96 participants received the femSense® system consisting of an adhesive axillary thermometer patch and a smartphone application, where patients were asked to document information about their previous 3 cycles. Based on the participants data, the app predicted the cycle length and the estimated day of ovulation. From these predictions, the most probable fertile window and the day for applying the patch were derived. Participants applied and activated the femSense® patch on the calculated date, from which the patch continuously recorded their body temperature throughout a period of up to 7 days to confirm ovulation. Patients documented their daily urinary LH test positivity, and a transvaginal ultrasound was performed on day cycle day 7, 10, 12 and 14/15 to investigate the growth of one dominant follicle. If a follicle reached 15 mm in diameter, an ultrasound examination was carried out every day consecutively until ovulation. On the day ovulation was detected, serum progesterone was measured to confirm the results of the ultrasound. The performance of femSense® was evaluated by comparing the day of ovulation confirmation with the results of ovulation prediction (LH test) and detection (transvaginal ultrasound). Results: The femSense® system confirmed ovulation occurrence in 60 cases (81.1%) compared to 48 predicted cases (64.9%) with the LH test (p = 0.041). Subgroup analysis revealed a positive trend for the femSense® system of specific ovulation confirmation within the fertile window of 24 h after ovulation in 42 of 74 cases (56.8%). Cycle length, therapy method or infertility reason of the patient did not influence accuracy of the femSense® system. Conclusions: The femSense® system poses a promising alternative to the traditional BBT method and is a valuable surrogate marker to transvaginal ultrasound for confirmation of ovulation.

SepN is a septal junction component required for gated cell-cell communication in the filamentous cyanobacterium Nostoc.

Multicellular organisms require controlled intercellular communication for their survival. Strains of the filamentous cyanobacterium Nostoc regulate cell-cell communication between sister cells via a conformational change in septal junctions. These multi-protein cell junctions consist of a septum spanning tube with a membrane-embedded plug at both ends, and a cap covering the plug on the cytoplasmic side. The identities of septal junction components are unknown, with exception of the protein FraD. Here, we identify and characterize a FraD-interacting protein, SepN, as the second component of septal junctions in Nostoc. We use cryo-electron tomography of cryo-focused ion beam-thinned cyanobacterial filaments to show that septal junctions in a sepN mutant lack a plug module and display an aberrant cap. The sepN mutant exhibits highly reduced cell-cell communication rates, as shown by fluorescence recovery after photobleaching experiments. Furthermore, the mutant is unable to gate molecule exchange through septal junctions and displays reduced filament survival after stress. Our data demonstrate the importance of controlling molecular diffusion between cells to ensure the survival of a multicellular organism.

Structure of a thylakoid-anchored contractile injection system in multicellular cyanobacteria.

Contractile injection systems (CISs) mediate cell-cell interactions by phage tail-like structures, using two distinct modes of action: extracellular CISs are released into the medium, while type 6 secretion systems (T6SSs) are attached to the cytoplasmic membrane and function upon cell-cell contact. Here, we characterized a CIS in the multicellular cyanobacterium Anabaena, with features distinct from extracellular CISs and T6SSs. Cryo-electron tomography of focused ion beam-milled cells revealed that CISs were anchored in thylakoid membrane stacks, facing the cell periphery. Single particle cryo-electron microscopy showed that this unique in situ localization was mediated by extensions of tail fibre and baseplate components. On stress, cyanobacteria induced the formation of ghost cells, presenting thylakoid-anchored CISs to the environment. Functional assays suggest that these CISs may mediate ghost cell formation and/or interactions of ghost cells with other organisms. Collectively, these data provide a framework for understanding the evolutionary re-engineering of CISs and potential roles of these CISs in cyanobacterial programmed cell death.

Pronounced Trace Element Variation in Follicular Fluids of Subfertile Women Undergoing Assisted Reproduction.

Female subfertility is a growing concern, especially in view of an increasing prevalence of polycystic ovary syndrome (PCOS). Assisted reproductive technologies (ART) offer a perspective for pregnancy, but the outcome rate is still suboptimal. The trace elements (TE), copper (Cu), selenium (Se), and zinc (Zn) are essential for fertility and development. We hypothesized that TE concentrations are related to oocyte quality and growth and affect pregnancy outcomes in women undergoing ART. Concentrations of TE were measured by total reflection X-ray fluorescence. Extracellular glutathione peroxidase 3 (GPX3) and selenoprotein P (SELENOP) were determined as additional Se biomarkers. Corresponding serum and follicular fluid (FF) samples were available from women with (n = 20) and without (n = 20) PCOS diagnosis undergoing hormone treatment within the ART procedure, respectively, and FF samples were classified into five groups based on morphological assessment. Serum showed higher TE concentrations than FF, and TE levels correlated positively between both matrices. Individual FF from the same women showed surprisingly high variability in TE concentration, and follicles without oocytes displayed the lowest TE concentrations. Both Se biomarkers GPX3 and SELENOP were present in FF and correlated positively to Se concentrations. Some notable relationships were observed between morphokinetic parameters, TE concentrations, and GPX3 activity. A slightly depressed serum Zn concentration was observed in PCOS. Our results indicate a direct relationship between TE in serum and FF, positive correlations between the three Se biomarkers in FF, and high variability between the FF from the same woman with the lowest TE concentrations in the follicles with the poorest quality. The differences observed in relation to PCOS diagnoses appear relatively minor. Collectively, the data support the notion that TE assessment of follicles may contribute to optimal oocyte selection and subsequently influence ART success.

Investigation of Non-invasive Continuous Body Temperature Measurements in a Clinical Setting Using an Adhesive Axillary Thermometer (SteadyTemp®).

Since the human body reacts to a variety of different diseases with elevated body temperature, measurement of body temperature remains relevant in clinical practice. The absolute temperature value for fever definition is still arbitrary and depends on the measuring site, as well as underlying disease and individual factors. Hence, a simple threshold for fever definition is outdated and a definition which relies on the relative changes in the individual seems reasonable as it takes these individual factors into account. In this prospective multicentric study we validate an adhesive axillary thermometer (SteadyTemp®) which allows continuous non-invasive temperature measurements. It consists of a patch to measure temperature and a smartphone application to process and visualize gathered data. This article provides information of the new diagnostic possibilities when using this wearable device and where it could be beneficial. Furthermore, it discusses how to interpret the generated data and when it is not practical to use, based on its characteristics and physiological phenomena.

Structural Determinants and Their Role in Cyanobacterial Morphogenesis.

Cells have to erect and sustain an organized and dynamically adaptable structure for an efficient mode of operation that allows drastic morphological changes during cell growth and cell division. These manifold tasks are complied by the so-called cytoskeleton and its associated proteins. In bacteria, FtsZ and MreB, the bacterial homologs to tubulin and actin, respectively, as well as coiled-coil-rich proteins of intermediate filament (IF)-like function to fulfil these tasks. Despite generally being characterized as Gram-negative, cyanobacteria have a remarkably thick peptidoglycan layer and possess Gram-positive-specific cell division proteins such as SepF and DivIVA-like proteins, besides Gram-negative and cyanobacterial-specific cell division proteins like MinE, SepI, ZipN (Ftn2) and ZipS (Ftn6). The diversity of cellular morphologies and cell growth strategies in cyanobacteria could therefore be the result of additional unidentified structural determinants such as cytoskeletal proteins. In this article, we review the current advances in the understanding of the cyanobacterial cell shape, cell division and cell growth.

Fully automated, sequential focused ion beam milling for cryo-electron tomography.

Cryo-electron tomography (cryoET) has become a powerful technique at the interface of structural biology and cell biology, due to its unique ability for imaging cells in their native state and determining structures of macromolecular complexes in their cellular context. A limitation of cryoET is its restriction to relatively thin samples. Sample thinning by cryo-focused ion beam (cryoFIB) milling has significantly expanded the range of samples that can be analyzed by cryoET. Unfortunately, cryoFIB milling is low-throughput, time-consuming and manual. Here, we report a method for fully automated sequential cryoFIB preparation of high-quality lamellae, including rough milling and polishing. We reproducibly applied this method to eukaryotic and bacterial model organisms, and show that the resulting lamellae are suitable for cryoET imaging and subtomogram averaging. Since our method reduces the time required for lamella preparation and minimizes the need for user input, we envision the technique will render previously inaccessible projects feasible.

Architecture and function of human uromodulin filaments in urinary tract infections.

Uromodulin is the most abundant protein in human urine, and it forms filaments that antagonize the adhesion of uropathogens; however, the filament structure and mechanism of protection remain poorly understood. We used cryo-electron tomography to show that the uromodulin filament consists of a zigzag-shaped backbone with laterally protruding arms. N-glycosylation mapping and biophysical assays revealed that uromodulin acts as a multivalent ligand for the bacterial type 1 pilus adhesin, presenting specific epitopes on the regularly spaced arms. Imaging of uromodulin-uropathogen interactions in vitro and in patient urine showed that uromodulin filaments associate with uropathogens and mediate bacterial aggregation, which likely prevents adhesion and allows clearance by micturition. These results provide a framework for understanding uromodulin in urinary tract infections and in its more enigmatic roles in physiology and disease.