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Interpretable deep learning reveals spatiotemporal MRI features of brain aging that align with neurodegenerationNARA Subscribed
Cortical thinning and atrophy are hallmarks of brain aging that have been characterized using magnetic resonance imaging (MRI). Brain aging involves many neuroanatomic features whose effects on brain structure remain unexplored. To address this challenge, we trained interpretable deep neural networks (DNNs) to estimate brain age (BA) from T 1 -weighted ( T 1 w) MRI. By identifying MRI features unapparent to humans, DNNs can fi...
This paper provides a platform for the following studies within this Special Issue. ‘Ecophysiology of fishes in the two great tributaries of the Amazon in the Anthropocene’. It documents the water quality conditions and accompanying zooplankton community structure and biomass relative to fish health in the Rio Negro and Rio Solimões during the extreme drought of 2023. Our goals were to document conditions, compare them with hi...
Contrasting thermal and hypoxic responses of species from blackwater and whitewater riversNARA Subscribed
In the Amazon basin, climate change is increasing water temperatures and CO₂ concentrations, which intensify environmental stressors for fish by increasing natural thermal regimes, reducing dissolved oxygen and pH levels. Extreme droughts, such as those recorded in 2023 and the new record set in 2024, have exacerbated these conditions and have led to widespread fish mortality. Amazonian rivers, which are characterized by contr...
The Amazonian loricariid fish Pterygoplichthys gibbiceps, from the Rio Negro, and Pterygoplichthys pardalis, from the Rio Solimões, are facultative air‐breathers that can use the stomach as an air‐breathing organ. Measurement of oxygen uptake under progressive aquatic hypoxia revealed a relatively high hypoxia resistance of both species. In both species, air‐breathing was initiated at aquatic PO 2 values below 3 kPa. In hypoxi...
Nitrogen excretion and oxygen consumption under severe hypoxia in s iluriform fishes from the A mazonNARA Subscribed
Siluriform fishes collected from the Rio Negro and Rio Solimões proved to be highly resistant to aquatic hypoxia. In all four species analysed in this study, aquatic oxygen consumption significantly decreased from normoxic levels at water PO 2 values near 1 kPa. Air‐breathing activity was observed only in Sturisoma sp. (Rio Negro). In this species, under severe hypoxia, oxygen uptake from the air dominated, but total oxygen up...
The tambaqui ( Colossoma macropomum , G. Cuvier 1818) thrives both in the ion‐poor waters of the Amazon and in commercial aquaculture. In both, environmental conditions can be harsh due to low ion levels, occasional high salt challenges (in aquaculture), low pH, extreme PO 2 levels (hypoxia and hyperoxia), high PCO 2 levels (hypercapnia), high ammonia levels (in aquaculture), and high and low temperatures. Ion transport across...
Increases in anthropogenic activities in the Amazon have led to pollution from trace metals, including copper. Dissolved organic carbon (DOC) is known to protect against metal toxicity and ionoregulatory disturbances in Amazonian fish, particularly at low pH. However, little is known about the effects of DOC and trace metals, such as copper, on the branchial water transport pathways. Water moves across the gills of fish throug...
Branchial localization of acid (A‐type) and base (B‐type) excreting ionocytes in Amazonian stenohaline freshwater Potamotrygon rayNARA Subscribed
The branchial epithelium of Potamotrygon —a member of the only strictly freshwater elasmobranch family Potamotrygonidae—was observed via immunohistochemistry, and two distinct forms of ionocytes were identified. The acid (A‐type) and base (B‐type) secreting cells with respective basolateral–apical localizations of Na + /K + ‐ATPase–Na + /H + exchanger 3 in A‐type and V‐type H + ‐ATPase–pendrin Cl − /HCO 3 − exchanger in B‐type...
Joint effects of elevated copper and temperature in juvenile Tambaqui exposed in black and white waters of the AmazonNARA Subscribed
This study aimed to investigate how exposure to elevated water temperature and metal concentration jointly affect the physiology of Amazonian fish. Aboard a research vessel in the Amazon, we evaluated the effects of water temperature (river T°C at 31.5°C and a + 4°C increase to 35.5°C) and of 3‐h copper (Cu) exposure (up to 600 μg/L) in juvenile Tambaqui ( Colossoma macropomum ) exposed in freshly collected Rio Negro (‘black w...
Optical characterization of dissolved organic carbon (DOC) freshly collected from the circumneutral “white water” of the Rio Solimoes revealed that it had lower aromaticity, lower molecular weight, and a greater autochthonous content than DOC from the acidic “black water” of the Rio Negro. The tambaqui ( Colossoma macropomum ), a characid member of the Serrasalmidae, is a model neotropical fish that migrates annually between t...
Alzheimer’s disease (AD) disproportionately affects women and carriers of the apolipoprotein E ε4 allele (APOE4), yet little is known about how sex and APOE interact to influence white matter (WM) integrity during disease progression. We integrated diffusion MRI and matched blood transcriptomic data to investigate these interactions and their underlying biological mechanisms. WM microstructure was quantified using diffusion te...
Leaf herbivory is a ubiquitous ecological interaction that varies significantly in intensity across species, habitats, and biogeographic regions. Although quantification of leaf damage is crucial for understanding many ecological processes, the accuracy and precision of various damage estimation methods used by researchers, including visual estimation, digital image analysis, and artificial intelligence, have not been evaluate...
Effect of climate change on potato yield and starch contentNARA Subscribed
Predicting the progression of MCI and Alzheimer’s disease on structural brain integrity and other features with machine learningNARA Subscribed
Machine learning (ML) on structural MRI data shows high potential for classifying Alzheimer’s disease (AD) progression, but the specific contribution of brain regions, demographics, and proteinopathy remains unclear. Using Alzheimer’s Disease Neuroimaging Initiative (ADNI) data, we applied an extreme gradient-boosting algorithm and SHAP (SHapley Additive exPlanations) values to classify cognitively normal (CN) older adults, th...