Bird eggshells are complex biomineralized materials composed of a mineral phase and an organic matrix that regulates crystal growth. In this study, we characterized the eggshell of Dromaius novaehollandiae using structural, chemical, proteomic, and in silico approaches to explore the role of intramineral proteins in biomineralization. Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM–EDS), Fourier-Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD) analyses showed that calcite is the predominant mineral phase; however, structural and chemical differences were identified compared to Gallus gallus, particularly in the organization of the internal fibrillar network and in components associated with the organic matrix. Proteomic analysis identified biomineralization-related proteins, including DCA-1 and DCA-2. Subsequently, microtitration and crystal growth assays showed that the protein fractions exhibit functional activity in Ca²⁺ and CO₃²⁻/HCO₃⁻ systems, suggesting differential affinities for Ca²⁺ and CO₃²⁻ species. Additionally, structural modeling using AlphaFold3 yielded the first three-dimensional models of DCA-1 and DCA-2 interacting with Ca²⁺ and CO₃²⁻. The models revealed distinct interaction patterns: DCA-1 exhibited a more distributed stabilization network for carbonate, whereas DCA-2 showed more concentrated regions associated with calcium and a more localized interaction with CO₃²⁻. Taken together, the results suggest that DCA-1 and DCA-2 participate complementarily in regulating the mineralizing microenvironment during shell formation made of calcite. This study provides new structural and functional evidence on intramineral proteins in paleognaths and contributes to understanding ancestral mechanisms of biomineralization.
Scorpions are an ancient chelicerate group with a fossil record extending back to the Silurian and a peak in reported fossil forms during the Carboniferous. Most Carboniferous scorpions are from Coal Measures sites, a small number of which exceptionally preserve evidence of respiratory structures. To expand the record of such material, we present a new fossil scorpion specimen from the Pennsylvanian (Bashkirian) Pottsville Formation from the Union Chapel Mine, Alabama, USA. We demonstrate that UV imagery is a useful tool for examining fossil scorpions, as it can clearly illustrate exoskeletal sections, and other important morphological structures. This specimen shows probable intrasternal spiracles, illustrating this is one of the oldest members of the derived scorpion infraorder Orthosterni, and potentially preserves evidence of book lungs. Due to the lack of taxonomically important features, such as coxosternal morphologies, we cannot identify the specimen beyond Orthosterni. We used Energy Dispersive X-Ray Spectroscopy (EDS) to explore fossil preservation, determining the specimen is preserved almost entirely as carbon, indicating it had undergone kerogenisation. This body fossil complements walking trace fossils from the same site attributed to scorpions, represents the first fossil scorpion from the southeastern USA, and provides more evidence for extensive diagenetic alteration of cuticle in fossil scorpions from Coal Measures.
Hydrothermal vents are widely considered plausible settings for the origin of life, owing to their steep redox gradients and the availability of chemical energy. Their capacity to support organic synthesis, molecular retention, and breakdown varies with local conditions. Here, I propose a conceptual framework for assessing whether connected environments could support complementary prebiotic chemical functions. Hydrothermal systems may contribute to the breakdown and reuse of supplied organic compounds alongside their constructive roles, while ice–water interfaces may support concentration, selected synthetic reactions, and product retention when suitable reactants are available. Producer-like, consumer-like, and decomposer-like functions are used as nonexclusive analogies for chemical production, use of supplied organic compounds, and breakdown yielding potentially reusable products; they do not denote demonstrated abiotic metabolisms. The central hypothesis is that life’s beginnings may have depended partly on transitions between environments, rather than on processes within any single environment alone. This proposal can be assessed by comparing coupled and isolated reaction systems for product survival, reuse, and sustained reaction activity. The article presents no new experimental validation, and neither the proposed environmental connections nor their contribution to the emergence of heritable metabolism or the last universal common ancestor is established.
The Present study aims to examine the physiological adaptability of Panicum turgidum growing in three different habitats: sand dunes, sandy plains, and saline areas. To assess how well plants adapted to rising salinity, physicochemical features of the soil, photosynthetic pigments, biochemical traits, and ionic contents were examined in root and stem tissues of P. turgidum. Five subsites were selected from each habitat, and the quadrat method was applied for vegetative sampling. Outcomes revealed that electrical conductivity (41.3 ± 0.3 dS m⁻1) and concentrations of Na⁺ (4967.9 ± 0.2 mg L⁻1) and Cl⁻ (2431.7 ± 0.3 mg L⁻1) increased from dunes to saline environments, indicating a distinct salinity gradient in the soil. However, under saline circumstances, chlorophyll a and b dramatically decreased, suggesting stress effects on photosynthesis. Osmolytes and stress-related metabolites, such as proline (294.8 ± 1.13 µg g− 1 FW), free amino acids (1593.7 ± 2.83 µg g− 1 FW), soluble proteins (1706.5 ± 1.07 µg g− 1 FW), and total soluble sugars (28.71 ± 0.44 mg g− 1 DW), gradually increased in saline environments. Antioxidants, including flavonoids (3.846 ± 0.04 mg g− 1 DW) and phenolics (11.35 ± 0.01 µg g− 1 FW), also showed greater accumulation in saline conditions, indicating improved protection against oxidative stress. The ion accumulation showed higher Na⁺ and Cl⁻ buildup in root and stem tissues, together with controlled levels of K⁺ and Ca²⁺. These findings indicate that P. turgidum has coordinated physiological responses that may help its survival in saline desert environments, including osmotic adjustment, antioxidant resistance, and ion control. These results suggest that P. turgidum may useful in future studies associated with saline land restoration and desert surroundings.
Feather mites are permanent ectosymbionts that occupy discrete feather microhabitats; however, little is known about how associations between dorsal and ventral taxa vary along continuous wing gradients. We examined feather-level spatial abundance associations between dorsal and ventral feather mites along the proximodistal axis of the wing in the Siberian Rubythroat (Calliope calliope) via nonlinear mixed-effects models. Dorsal feather mites (Trouessartia calliope) were largely absent from distal outer remiges (flight feathers) and increased toward proximal body-side remiges, whereas ventral feather mites (Proctophyllodes sp.) exhibited a positional gradient along the wing. When averaged across positions, the dorsal and ventral abundances showed only weak overall associations. However, position-specific analyses revealed that the dorsal–ventral slope was positive in distal outer remiges, declined toward mid-wing positions, and approached weakly negative values in the innermost secondaries. Because dorsal abundance was minimal distally, positive slopes in that region should not be interpreted as evidence of stable coexistence and may reflect responses to environmental constraints associated with distal wing positions. This position-dependent association was detected in breeding adult birds but not in juvenile birds, suggesting age-related differences in within-host spatial organization that may reflect the shorter time since mite transmission to juveniles and subsequent community assembly. Feather mite abundances were bilaterally symmetrical and showed no consistent effects of sex, date, or year, suggesting that host-level morphological stability provides a consistent spatial template for parasite organization. Together, these findings demonstrate that within-host feather mite assemblages exhibit spatially heterogeneous abundance associations along the wing, highlighting the importance of fine-scale spatial variation for understanding the organization and potential ecological relationships of cooccurring parasite taxa.
