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Abstract: During the Paleogene, bees diversified extensively after expanding from tropical regions into northern forests surrounding the future Baltic Sea, evolving alongside diverse angiosperms. Most fossil bee diversity is preserved in amber, which captures morphology but rarely behavior or ecology. Using synchrotron X-ray imaging, we describe a new leaf-cutter bee species, †Protolithurgus acarophorus sp. nov., from two specimens in Baltic amber. This is only the second known record of the extinct tribe †Protolithurgiini, which displays both ancestral and derived megachilid traits. The holotype preserves exceptional anatomical detail and reveals ecological insights, including compacted floral rewards in the hind-leg scopa, a pollen-carrying strategy rare in living Megachilidae. We also document the first fossil bee-mite association, suggesting unspecialized kleptoparasitic interactions, and reconstruct thoracic musculature dimensions. Together, these findings provide rare evidence of the foraging ecology, parasite relationships, and biomechanics of the earliest leaf-cutter bees.

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Abstract: Background/Objectives: Trabecular bone exhibits brittle behaviour governed by microscale deformation and damage, yet quantifying crack progression is difficult because classical fracture-mechanics approaches do not apply to architecturally discontinuous porous tissue. This pilot study evaluates whether synchrotron X-ray computed tomography (XCT) combined with digital volume correlation (DVC) can provide a practical, geometry-normalised approach for quantifying crack-opening behaviour in human trabecular bone. Methods: Semicylindrical specimens from femoral heads of hip-fracture donors (n = 5) and non-fracture controls (n = 5) underwent stepwise three-point bending during XCT imaging. Full-field displacement maps were used to measure crack mouth opening displacement (CMOD), crack length (a), and their ratio CMOD/a, used here as a geometry-normalised comparative descriptor of brittle response rather than an intrinsic material property. Automated phase-congruency crack detection (PCCD) was compared with manual measurement. Results: XCT–DVC resolved three-dimensional displacement discontinuities during crack initiation and propagation in all specimens. Hip-fracture donors exhibited significantly lower critical crack-opening ratios (CMOD/a)* than Controls (median 0.31 vs. 0.47; p = 0.008) and reached instability at lower applied loads. Total crack extension (Δa*) was similar between groups. Automated crack tracking using phase-congruency-based segmentation showed excellent agreement with manual measurements (r2 = 0.98), supporting reliable extraction of crack geometry from DVC displacement fields. Conclusions: In this small pilot sample, XCT–DVC provided a feasible, geometry-normalised approach for comparing crack-opening behaviour where classical fracture-mechanics parameters cannot be applied. The close agreement between automated and manual crack measurements supports the reproducibility of the displacement-based measurement pipeline. The lower critical CMOD/a in hip-fracture specimens may indicate a more brittle comparative response. However, given the small sample, differing sex distribution, and lower bone volume fraction in the hip-fracture group, these findings are preliminary and require confirmation in larger cohorts. Establishing whether the observed difference reflects intrinsic tissue brittleness, architectural factors, or both is an important objective for future work in microstructure-matched cohorts.

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Abstract: Maximum latewood density of conifers is the most widely used annual-resolution summer temperature proxy. Regions with few conifers, however, remain underrepresented in global paleoclimate records. Here, we use x-ray micro–computed tomography (micro-CT) to show that latewood density measurements of European beech (Fagus sylvatica L.) in a temperate lowland forest exhibit a strong summer (May to September) temperature signal (r = 0.73; 1833 to 2022 CE). Complementary wood anatomical analyses using deep learning segmentation reveal that both vessel and fiber anatomy are key drivers of latewood density variability and its temperature sensitivity. By integrating these anatomical responses, x-ray micro-CT–based latewood density measurements generate a robust and temporally stable summer temperature signal. Our results highlight the untapped potential of broad-leaved tree species for density-based climate reconstructions in temperate regions and open previously unidentified avenues for high-resolution paleoclimatology beyond the use of conifers.

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Abstract: Central to Alzheimer’s disease pathology are prefibrillar oligomer assemblies of amyloid-β (Aβ) peptide. A widely discussed hypothesis proposes that amyloid-β oligomers insert into neuronal lipid membranes, disrupting their integrity and causing a loss of cellular homeostasis in Alzheimer’s disease. This membrane disruption is believed to be a major source of Aβ-induced neurotoxicity. Cryo electron tomography (cryo-ET) has facilitated 3D nanoscale imaging of Aβ-membrane interactions under near-native conditions. Analyses of small extracellular vesicles (sEVs) reveals that Aβ oligomers including annular and curvilinear extended oligomers (CLEOs) exhibit extensive binding to cell-derived lipid membranes, including insertion into and carpeting of the lipid bilayer. Notably, these oligomeric assemblies were also internalized and concentrated within the cell-derived exosomes and other small sEVs. Enrichment of Aβ oligomers within the vesicles typically ranged between 5 to 20 times the external Aβ levels depending on the vesicle size and curvature. In contrast, monomeric and fibrillar forms of Aβ displayed minimal membrane interaction. Once internalized CLEOs appear to be trapped in an oligomeric form and do not readily go on to form fibrils. Studies with vesicles of brain lipid extract indicate the Aβ internalization does not require the presence of a membrane protein. Our in vitro studies underscore the membrane-disruptive capacity of oligomeric Aβ species and suggest a role of sEVs in concentrating toxic Aβ oligomers and transporting oligomers across the brain interstitium.

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Abstract: Vision is one of the most important senses used by animals and contributes to fundamental behaviors, including foraging, navigation, and mate detection and selection.1 Although much is known about how eye position and orientation correlate to ecology in the context of binocularity,2 animals with multipartite visual systems (more than two eyes) remain comparatively neglected. Spiders are highly successful predators that occupy a range of ecological niches and usually possess eight eyes. Here, we use three-dimensional geometric morphometrics and evolutionary modeling to test whether eye positions, orientations, and interocular angles correlate with hunting strategies in 52 species across the spider phylogeny. We demonstrate that eye configurations diversified from an ancestral medial cluster, as seen in modern trapdoor spiders, to a halo-like configuration in orb-weavers, and to the frontal clustering of eyes in several members of derived spider lineages. We show that visual hunters have the highest disparity and evolutionary rates in the configuration of their eyes but display a distinct morphological signature with multiple eye pairs concentrated at the front of the carapace. Moreover, we quantify the extent to which eye configuration is modular and show that the position and orientation of the eye pairs evolve semi-independently of each other. Our findings demonstrate that modularity in the spider visual system facilitates not only the specialization of individual eyes but also the whole architecture of the visual system, in line with different hunting strategies, body plans, and ecological niches.