Racer pigeons are renowned for their exceptional flying abilities, and Shiqi pigeons are meat pigeons prized for their tender and nutritious meat. This study investigated the physiological and metabolic differences between the two breeds under distinct breeding objectives by examining their feeding habits, carcass performance, meat quality, and intestinal development, thereby providing insights for pigeon breeding programs. Six racer and six Shiqi pigeons, each aged 28 d, were selected. They were fed a basal diet until 35 d of age, after which they were slaughtered for testing. Racer pigeons had substantially lower daily feed and pellet intake than Shiqi pigeons. There was no difference in the proportion of the major grains consumed. Slaughter traits, including live, carcass, semi-eviscerated weights, and weights of the spleen, gizzard, and bursa of Fabricius were substantially lower in racer pigeons. Racer pigeons had substantially higher pectoral muscle redness and yellowness at 45-min post-slaughter but lower pH values at 45 min and 24 h. Racer pigeons had substantially higher plasma GSH-Px activity and glucose concentrations. Racer pigeons had a higher pectoral muscle triglyceride (TG) content, greater duodenal weight and length, higher duodenal villus-to-lumen ratio, and elevated catalase (CAT) activity. However, they had a lower pectoral muscle GLU content and reduced jejunal weight and length. Compact racer pigeons are physiologically adapted for flight and are characterized by a strong antioxidant capacity and a well-developed duodenum. In contrast, the larger Shiqi pigeon, with a more developed jejunum and heavier pectoral muscles, was optimized for digestion and meat yield. These distinct profiles highlight the strong influence of genetic selection; the identified metrics offer valuable insights into targeted breed development.

The immature HIV-1 virion is assembled by the Gag polyprotein using inositol hexakisphosphate (IP6) as an essential assembly co-factor. Gag binds the genomic RNA Psi packaging signal via the nucleocapsid (NC) domain and associates with the plasma membrane via the matrix (MA) domain. Previous studies revealed that Gag exists in both compact (C) and extended (E) conformational states in solution. Only E-Gag formed virus-like particles with the correct size and IP6 shifted the equilibrium of DNA-bound Gag to the E state. The influence of specific RNA elements on this conformational change is unknown. In this work, a dual dye-labeled Gag was prepared for probing the effect of RNA binding on Gag conformation using Förster resonance energy transfer (FRET). In low salt and in the absence of other factors, Gag was primarily in the C state. Psi RNA binding induced a more significant FRET decrease than binding to non-Psi RNAs, consistent with a shift to E-Gag. IP6 alone also promoted the E-Gag state in the absence and presence of RNA. Atomistic molecular dynamics simulations are consistent with and provide detail into the role of NC-Psi RNA binding in the conformational switch of C-Gag to assembly-competent E-Gag. Simulations also showed that this switch is driven by capsid (CA) linker domain orientational flexibility and MA-CA unbinding dynamics. Thus, the highly flexible multi-domain Gag polyprotein leverages both viral and host cell factors to sample and stabilize distinct conformations, thereby orchestrating the viral assembly process.

Importance: APOE-ε4 is an established risk factor for Alzheimer's disease (AD) and confers greater risk in women than in men. Earlier age at menopause also increases AD risk in women. Yet whether menopause timing influences APOE-ε4 -related AD risk remains unclear. Objective: To examine whether age at menopause modifies the association of APOE-ε4 with AD risk. Design, setting and participants: Data were analyzed from postmenopausal women free from known dementia at study entry in two longitudinal datasets: (1) the harmonized data from the Religious Orders Study, Rush Memory and Aging Project, and Minority Aging Research Study (ROS/MAP/MARS), and (2) the Wisconsin Registry for Alzheimer's Prevention (WRAP). Data were collected between 1994-2025. Main outcomes and measures: In both datasets, neuropsychological tests assessed longitudinal memory performance, and MRI quantified cortical thickness and brain volume in AD vulnerable regions. In WRAP, which included in vivo AD biomarkers, AD pathology was assessed using longitudinal plasma p-tau217 and cross-sectional beta-amyloid (Aβ) PET. Menopause history was self-reported, and APOE status was classified as ε4 carrier vs. non-carrier. Linear mixed-effects or linear regression models were used, as appropriate, to test interactions between APOE-ε4 carrier status and age at menopause on memory decline, brain atrophy, p-tau217 accumulation, and Aβ-PET burden, adjusting for relevant covariates. Results: The study included 2,625 women in ROS/MAP/MARS (mean [ SD ] age=77.4 [7.77], mean [SD] age at menopause=47.9 [7.10]) and 512 women in WRAP (mean [SD] age=60.2 [5.57], mean [SD] age at menopause=50.1 [6.29]). In both datasets, earlier age at menopause strengthened associations of APOE-ε4 with memory decline (ROS/MAP/MARS: β=0.068, p =.02; WRAP: β=0.092, p =.03) and MRI measures of brain atrophy (ROS/MAP/MARS: β=0.071, p =.05; WRAP: β=0.256, p =.03). In WRAP, earlier menopause also amplified associations of APOE-ε4 with p-tau217 accumulation (β=-0.029, p =.05) and global Aβ-PET burden (β=-0.146, p =.01). Conclusions and relevance: Earlier menopause strengthened the associations between APOE -ε4 and key AD outcomes. These findings suggest that menopause timing may influence APOE -ε4-related susceptibility to AD, highlighting midlife endocrine processes as potential targets for prevention in women.

Ketamine produces rapid and sustained antidepressant effects after a single dose. Plasma membrane NMDA receptors are the presumptive primary molecular targets, yet how ketamine distributes, localizes, and engages neurons across cellular and subcellular compartments remains largely unknown. Ketamine, a lipophilic weak base, is thought to accumulate within acidic intracellular compartments, suggesting potential unrecognized sites of action. We developed a toolbox of genetically encoded intensity-based ketamine-sensing fluorescent reporters (iKetSnFRs) that specifically and robustly report R- or S-ketamine with cellular and subcellular resolution in vitro and in vivo , with excellent sensitivity and fluorescence change. iKetSnFR enables rapid detection of ketamine within seconds in the mouse prefrontal and visual cortex after intranasal or intraperitoneal dosing. We subsequently engineered compartment-targeted iKetSnFR variants, and in vivo imaging revealed that ketamine remains intracellularly and subcellularly engaged in neurons well after it is no longer detectable in circulation by LC-MS, at the plasma membrane of cortical neurons by iKetSnFR, or by electroencephalography. Furthermore, iKetSnFRs targeted across nine compartments reveal organelle-specific engagement of ketamine. This persistent intracellular engagement coincides with the prolonged timeframe of behavioral effects. Together, these findings link a single ketamine exposure to persistent intracellular drug dynamics and begin to provide a mechanistic basis for its rapid and enduring cellular and behavioral effects.

The Alzheimer's disease (AD) brain is characterized by dysregulated expression of multiple microRNAs (miRNA), positioning them as promising diagnostic and therapeutic targets. The levels of glia-enriched miR-223 are abnormal in the brains and plasma of AD patients and miR-223 is neuroprotective in models of stroke. However, whether miR-223 can be beneficial in AD is not known. Here, we report that intracerebroventricular (ICV) injection of miR-223 oligonucleotide mimic alleviated cognitive impairment, reduced amyloid beta (Aβ) pathology, and ameliorated the defects in synaptic marker expression in App [NL-G-F] AD model mice. Mechanistically, miR-223 induced microglial clustering around Aβ plaques with a concomitant upregulation of microglial phagocytic receptors AXL, TREM2 and CD11c, while pharmacological microglial depletion abolished the plaque-clearance phenotype. Moreover, in human iPSC-derived microglia miR-223 directly targeted multiple genes in the endo-lysosomal pathway, including AD risk gene SPPL2A , indicating that it acts as a major regulator of microglial phenotype. Lastly, long-term AAV-mediated overexpression of miR-223 recapitulates its beneficial effects on cognition, pathology, and synaptic marker expression. Our study demonstrates a novel approach for the treatment of AD using miR-223 and highlights the potential of RNAi-based therapeutics in neurodegenerative disease.

Glypican-3 (GPC3) is a heparan sulfate proteoglycan that is highly expressed in hepatocellular carcinoma and promotes tumor progression through Wnt3a/β-catenin signaling. However, how the nanoscale organization of GPC3 at the cell surface controls signaling remains unclear. Here, we combined nano-resolution MINFLUX imaging, single-molecule tracking, and functional assays to define the spatial architecture and dynamics of GPC3 on hepatoma cells. We found that GPC3 exists as both single molecules and nanoscale clusters and switches between confined and free diffusions on the plasma membrane. Heparan sulfate (HS) chains create nanoscale corrals that limit GPC3 movement, whereas removal of HS increases diffusive heterogeneity and disrupts confinement. Wnt3a stimulation induces the formation of higher-order GPC3 assemblies and enhances β-catenin signaling, while loss of HS markedly reduces this response. MINFLUX DNA-PAINT further revealed that HS chains orchestrate the spatial distribution of Wnt3a and promote its association with the Wnt receptor, Frizzled-1, an essential step for pathway activation. Collectively, these findings reveal that HS controls the nanoscale organization and dynamics of GPC3 to promote Wnt receptor assembly and efficient β-catenin signaling in hepatoma cells.

A transplanted lung offers a permissive milieu for local adaptive immune cell responses. Here, we characterize a transcriptionally and anatomically distinct adult lung-resident mesenchymal stromal population (MSC) that supports a pro-survival niche for antibody-secreting cells in rejecting lung allografts through a novel IL-6 trans-signaling/CXCL12 axis. By using a mouse orthotopic lung transplant model and Blimp1 [EYFP] recipients, we identify spatial localization of antibody-secreting cells (ASCs) and terminally differentiated plasma cells (PCs) along the bronchovascular bundles (BVBs). A previously described Foxf1 [+] Gli1 [+] Itga8 [-] subset of collagen- expressing MSCs, which forms a 3-dimensional network along the bronchovascular bundles (BVB-MSCs), was found to be the major source of the PC survival factors CXCL12 and IL-6. Cxcl12 [iCre/ERT2] Rosa26 [tdTomato] mice utilized as donors, validated the expansion of this population in a rejecting graft and their intimate association with ASCs. CXCL12 expression was increased in murine allografts and in Foxf1 [+] mesenchymal cells (MCs) isolated from human CLAD patients. IL-6 trans-signaling/STAT3 signaling axis was shown to upregulate CXCL12 secretion in human MCs, and Olamkicept-mediated neutralization of IL-6 trans-signaling in murine RAS attenuates CXCL12 expression, intra-graft ASC population, and fibrogenesis. Our findings represent the first delineation of specialized CXCL12-expressing mesenchymal stromal cells in adult lungs and the contribution of IL-6 trans-signaling driven CXCL12 expression to sustaining intra-graft ASC niches and allograft fibrogenesis.

Phospholipase C-β (PLCβ) enzymes are essential effectors of G protein-coupled receptor signaling that hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP2) at the plasma membrane to generate the second messengers inositol trisphosphate and diacylglycerol. PLCβs play essential roles in diverse physiological processes, including cardiac and neuronal function, macrophage activation, and the pathogenesis of diseases such as hypertrophic cardiomyopathy. PLCβ enzymes are unique in that they are aqueous-soluble and must partition onto the membrane surface to access their substrate, making membrane association a critical regulatory step. For example, we recently demonstrated that Gβγ activates PLCβ by membrane recruitment and orientation of the catalytic core on the membrane surface. Although PLCβ membrane recruitment is required for function, the molecular determinants governing this process remain incompletely understood. Using a quantitative membrane partitioning assay, we show that robust membrane association of PLCβ requires anionic phospholipids, whereas polar phospholipids cannot substitute. Membrane partitioning exhibits a steep dependence on anionic lipid abundance, which is mediated by electrostatic interactions between negatively charged lipids and basic residues within the distal C-terminal domain of PLCβ. We further demonstrate that anionic lipids cooperate with Gβγ to regulate PLCβ membrane recruitment, such that the magnitude of Gβγ-dependent recruitment is dictated by membrane anionic lipid content. These findings reconcile previous discrepancies regarding Gβγ-mediated PLCβ membrane recruitment and establish membrane electrostatics as a key regulatory input that integrates lipid composition with G protein signaling to regulate PLCβ activity.

The serotonin hypothesis of depression is still influential. We aimed to synthesise and evaluate evidence on whether depression is associated with lowered serotonin concentration or activity in a systematic umbrella review of the principal relevant areas of research. PubMed, EMBASE and PsycINFO were searched using terms appropriate to each area of research, from their inception until December 2020. Systematic reviews, meta-analyses and large data-set analyses in the following areas were identified: serotonin and serotonin metabolite, 5-HIAA, concentrations in body fluids; serotonin 5-HT1A receptor binding; serotonin transporter (SERT) levels measured by imaging or at post-mortem; tryptophan depletion studies; SERT gene associations and SERT geneenvironment interactions. Studies of depression associated with physical conditions and specific subtypes of depression (e.g. bipolar depression) were excluded. Two independent reviewers extracted the data and assessed the quality of included studies using the AMSTAR-2, an adapted AMSTAR-2, or the STREGA for a large genetic study. The certainty of study results was assessed using a modified version of the GRADE. We did not synthesise results of individual meta-analyses because they included overlapping studies. The review was registered with PROSPERO (CRD42020207203). 17 studies were included: 12 systematic reviews and meta-analyses, 1 collaborative meta-analysis, 1 meta-analysis of large cohort studies, 1 systematic review and narrative synthesis, 1 genetic association study and 1 umbrella review. Quality of reviews was variable with some genetic studies of high quality. Two meta-analyses of overlapping studies examining the serotonin metabolite, 5-HIAA, showed no association with depression (largest n = 1002). One meta-analysis of cohort studies of plasma serotonin showed no relationship with depression, and evidence that lowered serotonin concentration was associated with antidepressant use (n = 1869). Two meta-analyses of overlapping studies examining the 5-HT1A receptor (largest n = 561), and three meta-analyses of overlapping studies examining SERT binding (largest n = 1845) showed weak and inconsistent evidence of reduced binding in some areas, which would be consistent with increased synaptic availability of serotonin in people with depression, if this was the original, causal abnormaly. However, effects of prior antidepressant use were not reliably excluded. One meta-analysis of tryptophan depletion studies found no effect in most healthy volunteers (n = 566), but weak evidence of an effect in those with a family history of depression (n = 75). Another systematic review (n = 342) and a sample of ten subsequent studies (n = 407) found no effect in volunteers. No systematic review of tryptophan depletion studies has been performed since 2007. The two largest and highest quality studies of the SERT gene, one genetic association study (n = 115,257) and one collaborative meta-analysis (n = 43,165), revealed no evidence of an association with depression, or of an interaction between genotype, stress and depression. The main areas of serotonin research provide no consistent evidence of there being an association between serotonin and depression, and no support for the hypothesis that depression is caused by lowered serotonin activity or concentrations. Some evidence was consistent with the possibility that long-term antidepressant use reduces serotonin concentration. Appeared originally in Mol Psychiatry 2023; 28:3243-3256.