Cellular & Molecular Imaging

Bacteria occupy heterogeneous environments, attaching and growing within pores in materials, living hosts, and matrices like soil. Systems that permit high-resolution visualization of dynamic bacterial processes within the physical confines of a realistic and tractable porous media environment are rare. Here we use microfluidics to replicate the grain shape and packing density of natural sands in a 2D platform to study the flow-induced spatial evolution of bacterial biofilms underground. We introduce a wildtype strain (Pantoea sp. YR343, n=3) or an EPS-defective strain (Pantoea sp. YR343 ΔUDP, n=3) to the porous media platform and then simulate a rainfall event using gravity-driven flow of bacterial growth media.

The honeybee gut microbiota plays a key role in shaping host health and susceptibility to disease. Yet, the nutrient environment it experiences within the gut remains poorly characterized. In particular, little is known about the spatial distribution of nutrients across this community, as resolving such fine gradients in vivo has been technically challenging. Here, we engineer the native honeybee symbiont Snodgrassella alvi as a living biosensor to quantify the bioavailability of the dietary sugar arabinose within the gut. By expanding the genetic toolkit for S. alvi through chromosomal integration of high-burden genes and a suite of low-strength promoters, we achieve stable multi-gene expression without compromising host colonization. The resulting biosensor generates a specific, dose-dependent response to arabinose in situ, enabling visualization of sugar gradients across gut-associated bacterial biofilms at micron-scale resolution. Using this system, we show that diet-derived arabinose distribution is highly heterogeneous and can be influenced by the metabolic activity of co-colonizing Gilliamella species. These findings highlight how diet composition and microbial specialization generate fine-scale microenvironments within the gut. More broadly, this work further establishes S. alvi as a genetically tractable platform for in situ probing of microbial metabolism and nutrient distribution.

Mosquito-Alert http://www.mosquitoalert.com/ is a cooperative citizen science observatory coordinated by different public research institutions. Its main objective is to monitor the spread of invasive species of mosquitoes, particularly the tiger mosquito and the yellow fever mosquito, vectors of global diseases like Zika, Dengue and Chikungunya. The Mosquito-Alert app allows citizens to report a possible finding of the targeted species or their breeding places on the public space by sending images. The app collects the GPS position and other related information along with the image. Afterwards, a team of entomology experts validates the images. The validation is sent back to the participant and published in a public map of observations.

The Darwin Tree of Life project has the goal to sequence the genomes of 70,000 species of eukaryotic organisms in Britain and Ireland. This is a collection of photographs of the samples included in the study, provided by the National History Museum (NHM).

This upload contains photographs taken by Eva van der Heijden at the Butterfly Genetics Group at the University of Cambridge, from a collection of Hypolimnas misippus and Danaus chrysippus wings collected across Africa between 2011 and 2019. Individual sample names can be found in the information sheet. Further Information on individual samples (and other samples from the Butterfly Genetics Group Collection) can be found on the public database, Earthcape (https://heliconius.ecdb.io/). Please contact Chris Jiggins (c.jiggins[at]zoo.cam.ac.uk) or Anna Orteu (afarreo[at[gmail.com) for further information.

Phytoplankton is a minor fraction of the global biomass playing a major role in primary production and climate. Despite improved understanding of phytoplankton diversity and genomics, we lack nanoscale subcellular imaging approaches to understand their physiology and cell biology. Here, we present a complete Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) workflow (from sample preparation to image processing) to generate nanometric 3D phytoplankton models. Tomograms of entire cells, representatives of six ecologically-successful phytoplankton unicellular eukaryotes, were used for quantitative morphometric analysis. Besides lineage-specific cellular architectures, we observed common features related to cellular energy management: i) conserved cell-volume fractions occupied by the different organelles; ii) consistent plastid-mitochondria interactions, iii) constant volumetric ratios in these energy-producing organelles. We revealed detailed subcellular features related to chromatin organization and to biomineralization. Overall, this approach opens new perspectives to study phytoplankton acclimation responses to abiotic and biotic factors at a relevant biological scale.

The cyanoHAB forming cyanobacteria Microcystis and Planktothrix frequently produce high intracellular amounts of microcystins (MCs) or anabaenopeptins (APs). In this study, chemically modified MCs and APs have been localized on a subcellular level in Microcystis and Planktothrix applying copper-catalyzed alkyne-azide cycloaddition (CuACC). For this purpose, three different non-natural amino acids carrying alkyne or azide moieties were fed to individual P. agardhii strains No371/1 and CYA126/8 as well as to M. aeruginosa strain Hofbauer showing promiscuous incorporation of various amino acid substrates during non-ribosomal peptide synthesis (NRPS). Moreover, CYA126/8 peptide knock-out mutants and non-toxic strain Synechocystis PCC6803 were processed under identical conditions. Simultaneous labelling of modified peptides with ALEXA405 and ALEXA488 and lipid staining with BODIPY 505/515 were performed to investigate the intracellular location of the modified peptides. Pearson correlation coefficients (PCC) obtained from confocal images were calculated between the different fluorophores and the natural autofluorescence (AF), and between labelled modified peptides and dyed lipids to investigate the spatial overlap between peptides and the photosynthetic complex, and between peptides and lipids. Overall, labelling of modified MCs (M. aeruginosa) and APs (P. agardhii) using both fluorophores revealed in-creased intensity in MC/AP producing strains. For Synechocystis lacking NRPS, no labelling using either ALEXA405 or ALEXA488 was observed. Lipid staining in M. aeruginosa and Synechocystis was intense while in Planktothrix it was more variable. When compared with AF, both modified peptides and lipids showed a heterologous distribution. In comparison, the correlation between stained lipids and labelled peptides was not increased suggesting a reduced spatial overlap.

Multiplexed immunofluorescence images (4 stain, nuclear and cytoplasmic/membrane markers), single-cell segmentation, and tissue annotations for whole slide, developmental human manual digits.

The following data includes raw images, metadata, measurements and processed images as well as classifiers for image segmentations and masks created with the ImageJ/Fiji plugin Labkit to measure the leaf area. This dataset provides all acquired information for my Bachelor's thesis about leaf traits of Bryophyta related moss species.

Asymmetric localization of oskar RNP granules to the oocyte posterior is crucial for abdominal patterning and germline formation in the Drosophila embryo. We show that oskar RNP granules in the oocyte are condensates with solid-like physical properties. Using purified oskar RNA and scaffold proteins Bruno and Hrp48, we confirm in vitro that oskar granules undergo a liquid-to-solid phase transition. Whereas the liquid phase allows RNA incorporation, the solid phase precludes incorporation of additional RNA while allowing RNA-dependent partitioning of client proteins. Genetic modification of scaffold granule proteins, or tethering the intrinsically disordered region of human Fused in Sarcoma (FUS) to oskar mRNA, allowed modulation of granule material properties in vivo. The resulting liquid-like properties impaired oskar localization and translation with severe consequences on embryonic development. Our study reflects how physiological phase transitions shape RNA-protein condensates to regulate localization and expression of a maternal RNA that instructs germline formation.