Machine Learning Modeling of Aedes albopictus Habitat Suitability in the 21st Century.

The Asian tiger mosquito, Aedes albopictus, is an important vector of arboviruses that cause diseases such as dengue, chikungunya, and zika. The vector is highly invasive and adapted to survive in temperate northern territories outside its native tropical and sub-tropical range. Climate and socio-economic change are expected to facilitate its range expansion and exacerbate the global vector-borne disease burden. To project shifts in the global habitat suitability of the vector, we developed an ensemble machine learning model, incorporating a combination of a Random Forest and XGBoost binary classifiers, trained with a global collection of vector surveillance data and an extensive set of climate and environmental constraints. We demonstrate the reliable performance and wide applicability of the ensemble model in comparison to the known global presence of the vector, and project that suitable habitats will expand globally, most significantly in the northern hemisphere, putting at least an additional billion people at risk of vector-borne diseases by the middle of the 21st century. We project several highly populated areas of the world will be suitable for Ae. albopictus populations, such as the northern parts of the USA, Europe, and India by the end of the century, which highlights the need for coordinated preventive surveillance efforts of potential entry points by local authorities and stakeholders.

Entomological surveillance and spatiotemporal risk assessment of sand fly-borne diseases in Cyprus.

Visceral and cutaneous leishmaniases are important public health concerns in Cyprus. Although the diseases, historically prevalent on the island, were nearly eradicated by 1996, an increase in frequency and geographical spread has recently been recorded. Upward trends in leishmaniasis prevalence have largely been attributed to environmental changes that amplify the abundance and activity of its vector, the phlebotomine sand flies. Here, we performed an extensive field study across the island to map the sand fly fauna and compared the presence and distribution of the species found with historical records. We mapped the habitat preferences of Phlebotomus papatasi and P. tobbi, two medically important species, and predicted the seasonal abundance of P. papatasi at unprecedented spatiotemporal resolution using a climate-sensitive population dynamics model driven by high-resolution meteorological forecasting. Our compendium holds a record of 18 species and the locations of a subset, including those of potential public and veterinary health concern. We confirmed that P. papatasi is widespread, especially in densely urbanized areas, and predicted that its abundance uniformly peaks across the island at the end of summer. We identified potential hotspots of P. papatasi activity even after this peak. Our results form a foundation to inform public health planning and contribute to the development of effective, efficient, and environmentally sensitive strategies to control sand fly populations and prevent sand fly-borne diseases.

A dynamically structured matrix population model for insect life histories observed under variable environmental conditions.

Various environmental drivers influence life processes of insect vectors that transmit human disease. Life histories observed under experimental conditions can reveal such complex links; however, designing informative experiments for insects is challenging. Furthermore, inferences obtained under controlled conditions often extrapolate poorly to field conditions. Here, we introduce a pseudo-stage-structured population dynamics model to describe insect development as a renewal process with variable rates. The model permits representing realistic life stage durations under constant and variable environmental conditions. Using the model, we demonstrate how random environmental variations result in fluctuating development rates and affect stage duration. We apply the model to infer environmental dependencies from the life history observations of two common disease vectors, the southern (Culex quinquefasciatus) and northern (Culex pipiens) house mosquito. We identify photoperiod, in addition to temperature, as pivotal in regulating larva stage duration, and find that carefully timed life history observations under semi-field conditions accurately predict insect development throughout the year. The approach we describe augments existing methods of life table design and analysis, and contributes to the development of large-scale climate- and environment-driven population dynamics models for important disease vectors.

The impact of climatic factors on tick-related hospital visits and borreliosis incidence rates in European Russia.

Tick-borne diseases are among the challenges associated with warming climate. Many studies predict, and already note, expansion of ticks' habitats to the north, bringing previously non-endemic diseases, such as borreliosis and encephalitis, to the new areas. In addition, higher temperatures accelerate phases of ticks' development in areas where ticks have established populations. Earlier works have shown that meteorological parameters, such as temperature and humidity influence ticks' survival and define their areas of habitat. Here, we study the link between climatic parameters and tick-related hospital visits as well as borreliosis incidence rates focusing on European Russia. We have used yearly incidence rates of borreliosis spanning a period of 20 years (1997-2016) and weekly tick-related hospital visits spanning two years (2018-2019). We identify regions in Russia characterized by similar dynamics of incidence rates and dominating tick species. For each cluster, we find a set of climatic parameters that are significantly correlated with the incidence rates, though a linear regression approach using exclusively climatic parameters to incidence prediction was less than 50% effective. On a weekly timescale, we find correlations of different climatic parameters with hospital visits. Finally, we trained two long short-term memory neural network models to project the tick-related hospital visits until the end of the century, under the RCP8.5 climate scenario, and present our findings in the evolution of the tick season length for different regions in Russia. Our results show that the regions with an expected increase in both tick season length and borreliosis incidence rates are located in the southern forested areas of European Russia. Oppositely, our projections suggest no prolongation of the tick season length in the northern areas with already established tick population.

AIMSurv: First pan-European harmonized surveillance of Aedes invasive mosquito species of relevance for human vector-borne diseases.

Human and animal vector-borne diseases, particularly mosquito-borne diseases, are emerging or re-emerging worldwide. Six Aedes invasive mosquito (AIM) species were introduced to Europe since the 1970s: Aedes aegypti, Ae. albopictus, Ae. japonicus, Ae. koreicus, Ae. atropalpus and Ae. triseriatus. Here, we report the results of AIMSurv2020, the first pan-European surveillance effort for AIMs. Implemented by 42 volunteer teams from 24 countries. And presented in the form of a dataset named "AIMSurv Aedes Invasive Mosquito species harmonized surveillance in Europe. AIM-COST Action. Project ID: CA17108". AIMSurv2020 harmonizes field surveillance methodologies for sampling different AIMs life stages, frequency and minimum length of sampling period, and data reporting. Data include minimum requirements for sample types and recommended requirements for those teams with more resources. Data are published as a Darwin Core archive in the Global Biodiversity Information Facility- Spain, comprising a core file with 19,130 records (EventID) and an occurrences file with 19,743 records (OccurrenceID). AIM species recorded in AIMSurv2020 were Ae. albopictus, Ae. japonicus and Ae. koreicus, as well as native mosquito species.

Investigation of the pregnancy-induced muscle bundle dispersal of the inner myometrium of adult mouse uterus and its relationship to the metrial gland/MLAp.

In the adult uterus of mice, rats and humans, the initially closely packed muscle bundles of the inner myometrium (muscular tissue that encircles the endometrium where the conceptus implants) undergo a pregnancy-induced dispersal that is clinically significant and hypothesized to regulate important pregnancy events. However, where, when and how this dispersal occurs, what its functions are, as well as its spatial relationship to the mouse metrial gland/mesometrial lymphoid aggregate of pregnancy (MG/MLAp), are unknown. The MG/MLAp, is a pregnancy-induced uterine structure required for successful rodent pregnancy located mesometrial to (above) the decidua basalis (pregnancy-modified mesometrial endometrium) and defined by its accumulation of maternal lymphocytes known as uterine Natural Killer (uNK) cells. To begin to understand how mouse inner myometrium dispersal (IMD) occurs, we spatiotemporally described it by observing the distribution of its muscle bundles and measuring their volume fraction (VF), as well as the VF of uNKs and stromal cells of inner myometrium. We discovered that (a) IMD (defined as reduction in VF of inner myometrium muscle bundles) is restricted to the mesometrial half of the uterus, is first evident at Embryonic day (E) 5.5 (early postimplantation) but not at E3.5 (preimplantation), further increases between E6.5 and E7.5 and remains unchanged from E7.5 to E10.5, (b) IMD initiation (observed between E3.5 and E5.5) occurs in the absence of uNKs and is associated with VF increases of pre-existing inner myometrium stromal cells and (c) the IMD observed between E6.5 and E7.5 is not associated with VF increases of uNKs or stromal cells. To get functional clues about IMD, we examined whether stromal cells between the dispersed muscle bundles undergo decidualization (important for correct fetomaternal interactions) and provide evidence that they do by E10.5, based on their production of Desmin (decidualization marker). Lastly, we examined whether mouse MG/MLAp only comprises the dispersed inner myometrium or additionally includes the mesometrial triangle (a triangular-like area mesometrial to the inner myometrium at the mesometrium-uterus attachment site), as is the case in rats. Our data supports that the dispersed inner myometrium is the only tissue that makes up the mouse MG/MLAp. In conclusion, we provide novel cellular and spatiotemporal insights about IMD that will contribute to understanding its mechanism and function and allow more informed inter-species comparisons about this process.

Super-Resolution Fluorescence Microscopy Study of the Production of K1 Capsules by Escherichia coli: Evidence for the Differential Distribution of the Capsule at the Poles and the Equator of the Cell.

The production of Escherichia coli K1 serotype capsule was investigated using direct stochastic optical reconstruction microscopy with live bacteria and graphene oxide-coated coverslips, overcoming many morphological artifacts found in other high-resolution imaging techniques. Super-resolution fluorescence images showed that the K1 capsular polysaccharide is not uniformly distributed on the cell surface, as previously thought. These studies demonstrated that on the cell surfaces the K1 capsule at the poles had bimodal thicknesses of 238 ± 41 and 323 ± 62 nm, whereas at the equator, there was a monomodal thickness of 217 ± 29 nm. This bimodal variation was also observed in high-pressure light-scattering chromatography measurements of purified K1 capsular polysaccharide. Particle tracking demonstrated that the formation of the capsule was dominated by the expansion of lyso-phosphatidylglycerol (lyso-PG) rafts that anchor the capsular polysaccharide in the outer membrane, and the expansion of these rafts across the cell surface was driven by new material transported through the capsular biosynthesis channels. The discovery of thicker capsules at the poles of the cell will have implications in mediating interactions between the bacterium and its immediate environment.

Quenched Stochastic Optical Reconstruction Microscopy (qSTORM) with Graphene Oxide.

Quenched Stochastic Optical Reconstruction Microscopy (qSTORM) was demonstrated with graphene oxide sheets, peptides and bacteria; a method of contrast enhancement with super-resolution fluorescence microscopy. Individual sheets of graphene oxide (GO) were imaged with a resolution of 16 nm using the quenching of fluorescence emission by GO via its large Resonant Energy Transfer (RET) efficiency. The method was then extended to image self-assembled peptide aggregates (resolution 19 nm) and live bacterial cells (resolution 55 nm, the capsular structure of E. coli from urinary tract infections) with extremely low backgrounds and high contrasts (between one and two orders of magnitude contrast factor improvements that depended on the thickness of the graphene oxide layer used). Graphene oxide films combined with STORM imaging thus provide an extremely convenient method to image samples with large backgrounds due to non-specifically bound fluorophores (either due to excess labelling or autofluorescent molecules), which is a common occurrence in studies of both biological cells and soft-condensed matter. The GO quenches the fluorescence across a thin layer at distances of less than 15 nm. Graphene oxide films coated with thin layers (≤15 nm) of polystyrene, polymethylmethacrylate and polylysine are shown to be effective in producing high contrast qSTORM images, providing a convenient modulation of sample/substrate interactions. The GO coatings can also provide an increased image resolution and a factor of 2.3 improvement was observed with the peptide fibres using a feature of interest metric,when there was a large non-specifically bound background.

Functional and phenotypic distinction of the first two trophoblast subdivisions and identification of the border between them during early postimplantation: A prerequisite for understanding early patterning during placentogenesis.

The early stages of mouse placentogenesis (placenta formation) involve poorly understood patterning events within polar trophectoderm-derived trophoblast, the progenitor of all placental trophoblast cell types. By early postimplantation [embryonic day 5.5 (E5.5)], this patterning causes early trophoblast to become subdivided into extraembryonic ectoderm (ExE) and ectoplacental cone (EPC). A prerequisite to understanding this patterning requires knowing the location of ExE-EPC border and being able to distinguish the entire ExE from EPC at E5.5/E6.5, a time when the proamnioitic cavity within ExE is not fully established. However, these issues are unknown, as they have not been directly addressed. Here, we directly addressed these using trophoblast explant culture to functionally test for the location of ExE-EPC border, combined with phenotypic characterization of trophoblast proximal and distal to it. We show for the first time that the proximal-distal level of ExE-EPC border within E5.5/E6.5 trophoblast coincides with where Reichert's membrane (outermost basement membrane of conceptus) inserts into early trophoblast and with the proximal limit of extraembryonic visceral endoderm (primitive endoderm derivative covering part of early trophoblast). Based on these novel findings, we discovered that (a) the entire E5.5/E6.5 ExE can be distinguished from EPC because it is epithelial and specifically expresses Erf and Claudin4 and (b) at E5.5/E6.5, the entire EPC differs from ExE in that it is not epithelial and specifically expresses Snail. This work is expected to contribute to understanding the cellular and molecular basis of early trophoblast patterning during placentogenesis.

The flexibility and dynamics of the tubules in the endoplasmic reticulum.

The endoplasmic reticulum (ER) is a single organelle in eukaryotic cells that extends throughout the cell and is involved in a large number of cellular functions. Using a combination of fixed and live cells (human MRC5 lung cells) in diffraction limited and super-resolved fluorescence microscopy (STORM) experiments, we determined that the average persistence length of the ER tubules was 3.03 ± 0.24 µm. Removing the branched network junctions from the analysis caused a slight increase in the average persistence length to 4.71 ± 0.14 µm, and provides the tubule's persistence length with a moderate length scale dependence. The average radius of the tubules was 44.1 ± 3.2 nm. The bending rigidity of the ER tubule membranes was found to be 10.9 ± 1.2 kT (17.0 ± 1.3 kT without branch points). We investigated the dynamic behaviour of ER tubules in live cells, and found that the ER tubules behaved like semi-flexible fibres under tension. The majority of the ER tubules experienced equilibrium transverse fluctuations under tension, whereas a minority number of them had active super-diffusive motions driven by motor proteins. Cells thus actively modulate the dynamics of the ER in a well-defined manner, which is expected in turn to impact on its many functions.

Self-Assembly of Mesoscopic Peptide Surfactant Fibrils Investigated by STORM Super-Resolution Fluorescence Microscopy.

Super-resolution fluorescence microscopy, specifically stochastic reconstruction microscopy (STORM), and atomic force microscopy (AFM) were used to image the self-assembly processes of the peptide surfactant I3K. The peptide surfactants self-assembled into giant helical fibrils with diameters between 5 and 10 nm with significant helical twisting. The resolution of the STORM images was 30 nm, calculated using the Fourier ring correlation method. STORM compares favorably with AFM for the calculation of contour lengths (∼6 µm) and persistence lengths (10.1 ± 1.2 µm) due to its increased field of view (50 µm), and its ability to image bulk morphologies away from surfaces under ambient solution conditions. Two-color STORM experiments were performed to investigate the dynamic process of self-assembly after mixing of two separately labeled samples, and the results revealed the formation of long nanofibers via end-to-end connections of short ones. No evidence was found for significant monomer exchange between the samples, and the self-assembled structures were very stable and long-lived.

Reduction of coherent artefacts in super-resolution fluorescence localisation microscopy.

Super-resolution localisation microscopy techniques depend on uniform illumination across the field of view, otherwise the resolution is degraded, resulting in imaging artefacts such as fringes. Lasers are currently the light source of choice for switching fluorophores in PALM/STORM methods due to their high power and narrow bandwidth. However, the high coherence of these sources often creates interference phenomena in the microscopes, with associated fringes/speckle artefacts in the images. We quantitatively demonstrate the use of a polymer membrane speckle scrambler to reduce the effect of the coherence phenomena. The effects of speckle in the illumination plane, at the camera and after software localisation of the fluorophores, were characterised. Speckle phenomena degrade the resolution of the microscope at large length scales in reconstructed images, effects that were suppressed by the speckle scrambler, but the small length scale resolution is unchanged at ∼30 nm.

The mouse Foxi3 transcription factor is necessary for the development of posterior placodes.

The inner ear develops from the otic placode, one of the cranial placodes that arise from a region of ectoderm adjacent to the anterior neural plate called the pre-placodal domain. We have identified a Forkhead family transcription factor, Foxi3, that is expressed in the pre-placodal domain and down-regulated when the otic placode is induced. We now show that Foxi3 mutant mice do not form otic placodes as evidenced by expression changes in early molecular markers and the lack of thickened placodal ectoderm, an otic cup or otocyst. Some preplacodal genes downstream of Foxi3-Gata3, Six1 and Eya1-are not expressed in the ectoderm of Foxi3 mutant mice, and the ectoderm exhibits signs of increased apoptosis. We also show that Fgf signals from the hindbrain and cranial mesoderm, which are necessary for otic placode induction, are received by pre-placodal ectoderm in Foxi3 mutants, but do not initiate otic induction. Finally, we show that the epibranchial placodes that develop in close proximity to the otic placode and the mandibular division of the trigeminal ganglion are missing in Foxi3 mutants. Our data suggest that Foxi3 is necessary to prime pre-placodal ectoderm for the correct interpretation of inductive signals for the otic and epibranchial placodes.

A serum-free and defined medium for the culture of mammalian postimplantation embryos.

Whole embryo culture (WEC) of postimplantation rodent embryos is widely used for the study of mammalian embryogenesis and developmental toxicity testing. Its major advantage is that it allows direct access to embryos for experimental manipulations and the monitoring of their consequences that would otherwise not be possible or technically difficult to perform in utero. However, a major drawback of mammalian WEC is that the culture media currently in use display batch variations and are undefined, as they contain serum or serum replacements of unknown composition. Moreover, these media possess cell-signalling activities important for embryogenesis. Therefore, reproducibility of mammalian postimplantation WEC results may be affected by batch variation and their interpretation is complicated because the experimenter is unsure whether the embryo response to experimental perturbations is solely due to their action, or modified as a result of influences from undefined substances/signaling activities present in culture media. To alleviate these problems we investigated whether N2B27, a serum-free and defined medium, can support the in vitro development of postimplantation mammalian embryos. We show that N2B27 allows pre-gastrulation mouse embryos isolated at embryonic day 5.5 to develop to advanced gastrulation, reaching the mid- and late primitive streak stages. This is the first demonstration that postimplantation mammalian embryos can develop in vitro in a defined medium in the absence of serum and provides a novel WEC system for studying developmental mechanisms and testing for developmental toxicity during the early postimplantation period.

Reorganisation of the salivary mucin network by dietary components: insights from green tea polyphenols.

The salivary mucins that include MUC5B (gel-forming) and MUC7 (non-gel-forming) are major contributors to the protective mucus barrier in the oral cavity, and it is possible that dietary components may influence barrier properties. We show how one dietary compound, the green tea polyphenol epigallocatechin gallate (EGCG), can substantially alter the properties of both the polymeric MUC5B network and monomeric MUC7. Using rate-zonal centrifugation, MUC5B in human whole saliva and MUC5B purified from saliva sedimented faster in the presence of EGCG. The faster sedimentation by EGCG was shown to be greater with increasing MUC5B concentration. Particle tracking microrheology was employed to determine the viscosity of purified MUC5B solutions and showed that for MUC5B solutions of 200-1600 µg/mL, EGCG caused a significant increase in mucin viscosity, which was greater at higher MUC5B concentrations. Visualisation of the changes to the MUC5B network by EGCG was performed using atomic force microscopy, which demonstrated increased aggregation of MUC5B in a heterogeneous manner by EGCG. Using trypsin-resistant, high-molecular weight oligosaccharide-rich regions of MUC5B and recombinant N-terminal and C-terminal MUC5B proteins, we showed that EGCG causes aggregation at the protein domains of MUC5B, but not at the oligosaccharide-rich regions of the mucin. We also demonstrated that EGCG caused the majority of MUC7 in human whole saliva to aggregate. Furthermore, purified MUC7 also underwent a large increase in sedimentation rate in the presence of EGCG. In contrast, the green tea polyphenol epicatechin caused no change in the sedimentation rate of either MUC5B or MUC7 in human whole saliva. These findings have demonstrated how the properties of the mucin barrier can be influenced by dietary components. In the case of EGCG, these interactions may alter the function of MUC5B as a lubricant, contributing to the astringency (dry puckering sensation) of green tea.

Tea derived galloylated polyphenols cross-link purified gastrointestinal mucins.

Polyphenols derived from tea are thought to be important for human health. We show using a combination of particle tracking microrheology and small-angle neutron scattering that polyphenols acts as cross-linkers for purified gastrointestinal mucin, derived from the stomach and the duodenum. Both naturally derived purified polyphenols, and green and black tea extracts are shown to act as cross-linkers. The main active cross-linking component is found to be the galloylated forms of catechins. The viscosity, elasticity and relaxation time of the mucin solutions experience an order of magnitude change in value upon addition of the polyphenol cross-linkers. Similarly small-angle neutron scattering experiments demonstrate a sol-gel transition with the addition of polyphenols, with a large increase in the scattering at low angles, which is attributed to the formation of large scale (>10 nm) heterogeneities during gelation. Cross-linking of mucins by polyphenols is thus expected to have an impact on the physicochemical environment of both the stomach and duodenum; polyphenols are expected to modulate the barrier properties of mucus, nutrient absorption through mucus and the viscoelastic microenvironments of intestinal bacteria.

A combined small-angle X-ray and neutron scattering study of the structure of purified soluble gastrointestinal mucins.

The structures of purified soluble porcine gastric (Muc5ac) and duodenal (Muc2) mucin solutions at neutral and acidic pH were examined using small-angle X-ray scattering and small-angle neutron scattering experiments. We provide evidence for the morphology of the network above the semidilute overlap concentration and above the entanglement concentration. Furthermore, we investigated the gelation of both types of mucin solutions in response to a reduction in pH, where we observed the formation of large-scale heterogeneities within the polymer solutions, typical of microphase-separated gels. The concentration dependence of the inhomogeneity length scale (Ξ) and the amplitude of the excess scattering intensity [I(ex) (0)] are consistent with previously studied gelled synthetic polymeric systems. The persistence lengths of the chains were found to be similar for both Muc5ac and Muc2 from Kratky plots of the neutron data (8 ± 2 nm).

Particle tracking microrheology of purified gastrointestinal mucins.

The rheological characteristics of gastric and duodenal mucin solutions, the building blocks of the mucus layer that covers the epithelia of the two organs, were investigated using particle tracking microrheology. We used biochemically well characterized purified porcine mucins (MUC5AC and MUC2) as models for human mucins, to probe their viscoelasticity as a function of mucin concentration and pH. Furthermore, we used both reducing (dithiothreitol, DTT) and chaotropic agents (guanidinium chloride and urea) to probe the mesoscopic forces that mediate the integrity of the polymer network. At neutral pH both gastric and duodenal mucins formed self-assembled semi-dilute networks above a certain critical mucin concentration (c*) with the viscosity (η) scaling as η∼c(0.53±0.08) for MUC5AC and η∼c(0.53±0.06) for MUC2, where c is the mucin concentration. Above an even higher mucin concentration threshold (ce , the entanglement concentration) reptation occurs and there is a dramatic increase in the viscosity scaling, η∼c(3.92±0.38) for MUC5AC and η∼c(5.1±0.8) for MUC2. The dynamics of the self-assembled comb polymers is examined in terms of a scaling model for flexible polyelectrolyte combs. Both duodenum and gastric mucin are found to be pH switchable gels, gelation occurring at low pHs. There is a hundred-fold increase in the elastic shear modulus once the pH is decreased. The addition of DTT, guanidinium chloride and urea disassembles both the semi-dilute and gel structures causing a large increase in the compliance (decrease in their shear moduli). Addition of the polyphenol EGCG has a reverse effect on mucin viscoelasticity, that is, it triggers a sol-gel transition in semi-dilute mucin solutions at neutral pH.

Ets2-dependent trophoblast signalling is required for gastrulation progression after primitive streak initiation.

Although extraembryonic ectoderm trophoblast signals the embryo for primitive streak initiation, a prerequisite for gastrulation, it is unknown whether it also signals for the progression of gastrulation after primitive streak initiation. Here, using Ets2-/- mice, we show that trophoblast signalling is also required in vivo for primitive streak elongation, completion of intraembryonic mesoderm epithelial-mesenchymal transition and the development of anterior primitive streak derivatives such as the node. We show that Ets2-dependent trophoblast signalling is required for the maintenance of high levels of Nodal and Wnt3 expression in the epiblast and for the induction of Snail expression in the primitive streak, between embryonic day 6.3 and 6.7. Within extraembryonic ectoderm trophoblast, Ets2 maintains the expression of the transcription factors Elf5, Cdx2 and Eomes, and that of the signalling molecule Bmp4. We propose a model that provides a genetic explanation as to how Ets2 in trophoblast mediates the progression of gastrulation within the epiblast.

Novel spatiotemporal glycome changes in the murine placenta during placentation based on BS-I lectin binding patterns.

Although spatiotemporal changes of the glycome (full set of glycans, otherwise known as saccharides or carbohydrates) during placenta formation (placentation) are functionally and clinically important, they are poorly defined. Here, we elucidated novel aspects of the glycome during mouse placentation, from embryonic day 6.5 (E6.5) to E12.5, by investigating the largely unexplored binding distribution of lectin I from Bandeiraea simplicifolia (BS-I lectin), a glycan-binding protein that recognizes the DGalNAc and DGal glycans found at the terminal ends of specific oligosaccharides attached to lipids or proteins. We show that BS-I lectin binding marks all trophoblast cells during early placentation (E7.5 and E8.5 stages), continues in labyrinthine and junctional zone trophoblast but is lost from parietal trophoblast giant cells by E10.5/E11.5 (definitive placenta stage) and is lost from all trophoblast types, but marks the fetal capillary endothelium of the labyrinth, by E12.5. In the decidua basalis (the maternal part of the placenta), BS-I lectin positivity mainly marks the decidual stroma cells of the venous sinusoid area (E7.5 and E8.5 stages) and the entire decidua basalis by E10.5, as well as the osteopontin-positive subset of uterine natural killer (uNK) cells from E7.5 onwards. This work provides the first comprehensive description of the hitherto ill-defined spatiotemporal binding distribution of BS-I lectin in the fetal and maternal placenta between E6.5 and E12.5, thereby contributing to glycome elucidation during placentation. It also establishes BS-I lectin positivity as a novel pan-trophoblast marker during early placentation and as a new marker for mature uNK cells from E7.5 onwards.