Ligang Hu

Phototrophic iron mineralization (PIM) is a keystone biogeochemical process linking anoxic iron redox transformations to carbon sequestration. Although PIM is widely documented, how Fe(II) speciation impacts cell physiology and thus causes divergent mineralization phenotypes remains poorly understood. In this study, we systematically investigated the physiological, mineralogical, and molecular responses of a newly isolated photoferrotroph, Rhodopseudomonas palustris SX2, exposed to uncomplexed Fe(II) [Fe(II) without OM] versus organically complexed Fe(II) [Fe(II)-OM] under anoxic and illuminated conditions. We demonstrate that distinct Fe(II) speciation drives divergent metabolic reprogramming for rapid metabolic adaptation and phototrophic biomineralization phenotypes. Fe(II) without OM triggered cell-surface encrustation and activated stress-mitigation and metal-efflux systems, whereas Fe(II)-OM stimulated the formation of discrete intracellular iron nanoparticles while upregulating photosynthetic light harvesting and autotrophic CO2 fixation. Furthermore, genetic knockout and complementation confirmed that the pioABC operon constitutes the indispensable electron conduit driving Fe(II) oxidation across both speciation regimes, with organic complexation significantly enhancing its transcriptional activation. Our findings reveal how metabolic adaptation driven by Fe(II) speciation dictates the spatial distribution of biogenic iron minerals and regulates the efficiency of coupled carbon sequestration in anoxic ecosystems.

The health threat from airborne nanoplastics (NPs) remains unclear, as despite inhalation being a more direct brain entry route than ingestion, current understanding relies on oral exposure and commercial particle models that obscure realistic risks. Here, by integrating environmentally simulated polyethylene terephthalate (PET)-NPs with an aerosol inhalation model that mirrors real-world human exposure (0.1, 1, and 10 mg/m3), we demonstrate that chronic NP inhalation translocated to the brain and induced demyelination, neuroinflammation, and cognitive deficits. The most pronounced effects were observed at the highest exposure dose (10 mg/m3), which is relevant to the occupational settings. Mechanistically, NP exposure triggered astrocytic CXCL12 release, leading to CXCR4-dependent microglial activation and cytokine network dysregulation. In vitro, blockade of CXCR4 with AMD3100 attenuated NP-induced microglial migration and oligodendrocytic myelin basic protein reduction. Our study thus definitively links realistic airborne NP exposure to the key neuropathological features of demyelinating disorders and pinpoints a modifiable molecular pathway that could inform exposure-based preventive strategies. These findings underscore the need for further assessment of airborne NP risks, particularly in occupational settings.

Aqueous interfaces, such as those formed at the surface of microdroplets, can spontaneously generate reactive species, driving the critical redox reactions. This raises a pivotal question: could such laboratory-observed interfacial phenomena be integrated into our broader understanding of pollutant transformation and transport dynamics? In this perspective, we discuss this issue in the context of climate warming and changes in hydrological processes, focusing on how these environmental changes may alter the occurrence, composition, and reaction conditions of aqueous interfaces. Notably, aqueous interfaces may represent a previously underrecognized factor influencing the fate and transport of global pollutants, such as mercury. Bridging laboratory findings with field observations will be essential for linking microscale interfacial chemistry to macroscale environmental outcomes, ultimately improving predictive models of global pollutant cycling in a warming world.

Bioessential elements are essential for maintaining reproductive function, yet their homeostasis may be perturbed during aging. The dynamic regulation of these elements during aging remains insufficiently characterized. Here, a multielement single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) method was established for the quantification of seven bioessential elements, including iron (Fe), copper (Cu), calcium (Ca), zinc (Zn), magnesium (Mg), phosphorus (P) and manganese (Mn). This method was optimized using an integrated strategy to balance sensitivity, transport efficiency, and signal-to-noise ratio, and subsequently applied to quantify elemental contents in sperm collected from mice at different ages. Distinct age-dependent patterns were observed at the single-sperm level. Fe, Cu, and Ca exhibited early life maxima, whereas Zn, Mg, and P reached peak levels in midlife; Mn remained consistently low across all age groups. Interestingly, elemental heterogeneity followed a conserved inverted U-shaped trajectory, reaching a maximum at week 40. Correlation network analysis revealed a significant association between Fe and Mn at the content level, whereas elevated P content and increased heterogeneity were associated with reduced sperm concentration and impaired morphology. Functionally, Zn content was positively correlated with sperm motility, whereas elevated P content and increased heterogeneity were associated with reduced sperm concentration and impaired morphology. Ca, P, Mn, and Fe were more susceptible to dysregulation linked to compromised sperm function, whereas Mg, Zn, and Cu were associated with beneficial outcomes. These findings provide single-cell insights into age-dependent elemental homeostasis and its functional implications for male reproductive aging.

Nanoplastics (NPs) in aquatic environments raise concerns as carriers that alter the bioavailability of co-occurring pollutants, such as cadmium (Cd), affecting combined toxicity. Precision toxicology now demands single-cell assessments to provide novel insights into pollutant interactions. In this study, we utilized a 3D-printed droplet microfluidic platform integrated with time-resolved analysis (TRA)─inductively coupled plasma mass spectrometry (ICP-MS)─to investigate the uptake behavior of single algal cells exposed to Cd and Eu-containing polystyrene (PS) NPs. 3D printing enables rapid prototyping and design flexibility for optimized microfluidic chips, while the monolithic structure eliminates assembly errors, reduces dead volume, and supports large-scale production. The droplet platform offers high-throughput single-cell encapsulation; coupled with TRA-ICP-MS, it minimizes cross-contamination and enhances sensitivity for multielement single-cell analysis. Single-cell analysis revealed that coexposure increased both the proportion of Eu/Cd-containing cells and the uptaken Eu/Cd content. The adsorption of Cd²⁺ imparted a more positive surface charge to PS NPs. This promoted heterogeneous aggregation between algal cells and PS NPs, thereby enhancing the bioavailability of PS/Cd²⁺ to the algae. Complementing these single-cell measurements, bulk-cell assays were conducted to evaluate the toxicological impacts of coexposure to Cd and PS NPs on microalgae. The results demonstrate that coexposure to PS NPs and Cd²⁺ resulted in synergistic effects, including enhanced growth inhibition, photosynthetic impairment, membrane damage, and increased secretion of extracellular polymers. These findings highlight the increased ecological risks posed to aquatic organisms by the coexposure to PS NPs and Cd²⁺, emphasizing the need for comprehensive assessments of nanoplastic-pollutant interactions in aquatic ecosystems.