Clinging to the top: natal dispersal tracks climate gradient in a trailing-edge population of a migratory songbird.

PURPOSE: Trailing-edge populations at the low-latitude, receding edge of a shifting range face high extinction risk from climate change unless they are able to track optimal environmental conditions through dispersal. METHODS: We fit dispersal models to the locations of 3165 individually-marked black-throated blue warblers (Setophaga caerulescens) in the southern Appalachian Mountains in North Carolina, USA from 2002 to 2023. Black-throated blue warbler breeding abundance in this population has remained relatively stable at colder and wetter areas at higher elevations but has declined at warmer and drier areas at lower elevations. RESULTS: Median dispersal distance of young warblers was 917 m (range 23-3200 m), and dispersal tended to be directed away from warm and dry locations. In contrast, adults exhibited strong site fidelity between breeding seasons and rarely dispersed more than 100 m (range 10-1300 m). Consequently, adult dispersal kernels were much more compact and symmetric than natal dispersal kernels, suggesting adult dispersal is unlikely a driving force of declines in this population. CONCLUSION: Our findings suggest that directional natal dispersal may mitigate fitness costs for trailing-edge populations by allowing individuals to track changing climate and avoid warming conditions at warm-edge range boundaries.

Supramolecular Control of the Temperature Responsiveness of Fluorescent Macrocyclic Molecular Rotamers.

To fully harness the potential of molecular machines, it is crucial to develop methods by which to exert control over their speed of motion through the application of external stimuli. A conformationally strained macrocyclic fluorescent rotamer, CarROT, displays a reproducible and linear fluorescence decrease towards temperature over the physiological temperature range. Through the external addition of anions, cations or through deprotonation, the compound can access four discreet rotational speeds via supramolecular interactions (very slow, slow, fast and very fast) which in turn stop, reduce or enhance the thermoluminescent properties due to increasing or decreasing non-radiative decay processes, thereby providing a means to externally control the temperature sensitivity of the system. Through comparison with analogues with a higher degree of conformational freedom, the high thermosensitivity of CarROT over the physiological temperature range was determined to be due to conformational strain, which causes a high energy barrier to rotation over this range. Analogues with a higher degree of conformational freedom display lower sensitivities towards temperature over the same temperature range. This study provides an example of an information rich small molecule, in which programable rotational speed states can be observed with facile read-out.

Synthesis, Structure, and Properties of 2O-BaPtO3, a Phase Derived from Hexagonal Perovskite.

We have made the compound 2O-BaPtO3 by high-pressure, high-temperature synthesis, determined its structure, and tested its catalytic activity. Compounds of the same stoichiometry have been reported and tentatively identified as hexagonal perovskites, and although no structural model was ever established, 2O-BaPtO3 is clearly different and, to the best of our knowledge, unique. It features continuous chains of face-sharing PtO6 octahedra, like the well-known 2H hexagonal perovskite type, but with a staggered offset between the chains that breaks hexagonal symmetry and disrupts the close-packed array of A = Ba and X = O that is a defining characteristic of ABX3 perovskites. We investigated this structure and its stability vs the conventional 2H form using X-ray and neutron diffraction, X-ray absorption spectroscopy, and ab initio calculations. Catalytic testing of 2O-BaPtO3 showed that it is active for hydrogen evolution.

Discovery and heterologous biosynthesis of glycosylated polyketide luteodienoside A reveals unprecedented glucinol-mediated product offloading by a fungal carnitine O-acyltransferase domain.

Luteodienoside A is a novel glycosylated polyketide produced by the Australian fungus Aspergillus luteorubrus MST-FP2246, consisting of an unusual 1-O-ß-d-glucopyranosyl-myo-inositol (glucinol) ester of 3-hydroxy-2,2,4-trimethylocta-4,6-dienoic acid. Mining the genome of A. luteorubrus identified a putative gene cluster for luteodienoside A biosynthesis (ltb), harbouring a highly reducing polyketide synthase (HR-PKS, LtbA) fused at its C-terminus to a carnitine O-acyltransferase (cAT) domain. Heterologous pathway reconstitution in Aspergillus nidulans, substrate feeding assays and gene truncation confirmed the identity of the ltb cluster and demonstrated that the cAT domain is essential for offloading luteodienoside A from the upstream HR-PKS. Unlike previously characterised cAT domains, the LtbA cAT domain uses glucinol as an offloading substrate to release the product from the HR-PKS. Furthermore, the PKS methyltransferase (MT) domain is capable of catalysing gem-dimethylation of the 3-hydroxy-2,2,4-trimethylocta-4,6-dienoic acid intermediate, without requiring reversible product release and recapture by the cAT domain. This study expands the repertoire of polyketide modifications known to be catalysed by cAT domains and highlights the potential of mining fungal genomes for this subclass of fungal PKSs to discover new structurally diverse secondary metabolites.

Iodoetherification as a strategy towards sp3-rich scaffolds for drug discovery.

Functionalised tetrahydropyran and spirooxepane scaffolds were prepared utilising an iodoetherification strategy and elaborated to demonstrate their potential use in library synthesis. The iodoetherification products could be readily transformed to the corresponding azides that could be further functionalised via copper-catalysed azide-alkyne cycloaddition or reduction to the amine. The lead-likeness and three-dimensionality of the scaffolds were examined and compared to commercial libraries.

Differential transmetallation of complexes of the anti-cancer thiosemicarbazone, Dp4e4mT: effects on anti-proliferative efficacy, redox activity, oxy-myoglobin and oxy-hemoglobin oxidation.

The di-2-pyridylthiosemicarbazone (DpT) analogs demonstrate potent and selective anti-proliferative activity against human tumors. The current investigation reports the synthesis and chemical and biological characterization of the Fe(iii), Co(iii), Ni(ii), Cu(ii), Zn(ii), Ga(iii), and Pd(ii) complexes of the promising second generation DpT analog, di-2-pyridylketone-4-ethyl-4-methyl-3-thiosemicarbazone (Dp4e4mT). These studies demonstrate that the Dp4e4mT Co(iii), Ni(ii), and Pd(ii) complexes display distinct biological activity versus those with Cu(ii), Zn(ii), and Ga(iii) regarding anti-proliferative efficacy against cancer cells and a detrimental off-target effect involving oxidation of oxy-myoglobin (oxy-Mb) and oxy-hemoglobin (oxy-Hb). With regards to anti-proliferative activity, the Zn(ii) and Ga(iii) Dp4e4mT complexes demonstrate facile transmetallation with Cu(ii), resulting in efficacy against tumor cells that is strikingly similar to the Dp4e4mT Cu(ii) complex (IC50: 0.003-0.006 µM and 72 h). Relative to the Zn(ii) and Ga(iii) Dp4e4mT complexes, the Dp4e4mT Ni(ii) complex demonstrates kinetically slow transmetallation with Cu(ii) and intermediate anti-proliferative effects (IC50: 0.018-0.076 µM after 72 h). In contrast, the Co(iii) and Pd(ii) complexes demonstrate poor anti-proliferative activity (IC50: 0.262-1.570 µM after 72 h), probably due to a lack of transmetallation with Cu(ii). The poor efficacy of the Dp4e4mT Co(iii), Ni(ii), and Pd(ii) complexes to transmetallate with Fe(iii) markedly suppresses the oxidation of oxy-Mb and oxy-Hb. In contrast, the 2 : 1 Dp4e4mT: Cu(ii), Zn(ii), and Ga(iii) complexes demonstrate facile reactions with Fe(iii), leading to the redox active Dp4e4mT Fe(iii) complex and oxy-Mb and oxy-Hb oxidation. This study demonstrates the key role of differential transmetallation of Dp4e4mT complexes that has therapeutic ramifications for their use as anti-cancer agents.

Azide-Assisted Growth of Copper Nanostructures and Their Application as a Carbon Supported Catalyst in Two-Step Three-Component Azide-Alkyne Cycloadditions.

Copper nanostructures were obtained from the reduction of Cu(I) under mild conditions in ethanol/water using sodium-l-ascorbate and sodium azide while performing an amination reaction. When the halobenzene substrate was reacted in the presence of a bulk carbon black (CB) support, clustered copper sub-micrometer particles (SMPs) and microparticles (MPs) form. The growth conditions of the MPs were optimized, and the supported nanostructures were isolated and characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetry, and inductively-coupled plasma mass spectrometry. The particles are mobile and supported within the CB matrix and proved to be active catalysts in the azide-alkyne cycloaddition (CuAAC). The catalytic competency of the particles was assessed in a two-step three-component azide-alkyne cycloaddition of benzyl bromide, sodium azide, and phenylacetylene as a model reaction. The reaction conditions were optimized, and the optimized conditions were applied for the synthesis of triazole compounds with varying levels of functionalization. The recyclability of the catalysts was investigated, depletion modes were discussed, and the conditions were fine-tuned to reach good recyclability. This demonstrates the broader applicability of the SMPs/MPs as CuAAC-catalyst and its limitations.

Reciprocal discoidin domain receptor signaling strengthens integrin adhesion to connect adjacent tissues.

Separate tissues connect through adjoining basement membranes to carry out molecular barrier, exchange, and organ support functions. Cell adhesion at these connections must be robust and balanced to withstand independent tissue movement. Yet, how cells achieve synchronized adhesion to connect tissues is unknown. Here, we have investigated this question using the Caenorhabditis elegans utse-seam tissue connection that supports the uterus during egg-laying. Through genetics, quantitative fluorescence, and cell-specific molecular disruption, we show that type IV collagen, which fastens the linkage, also activates the collagen receptor discoidin domain receptor-2 (DDR-2) in both the utse and seam. RNAi depletion, genome editing, and photobleaching experiments revealed that DDR-2 signals through LET-60/Ras to coordinately strengthen an integrin adhesion in the utse and seam that stabilizes their connection. These results uncover a synchronizing mechanism for robust adhesion during tissue connection, where collagen both affixes the linkage and signals to both tissues to bolster their adhesion.

Discovery of new imidazotetrazinones with potential to overcome tumor resistance.

We describe the design, organic synthesis, and characterization, including X-ray crystallography, of a series of novel analogues of the clinically used antitumor agent temozolomide, together with their in vitro biological evaluation. The work has resulted in the discovery of a new series of anticancer imidazotetrazines that offer the potential to overcome the resistance mounted by tumors against temozolomide. The rationally designed compounds that incorporate a propargyl alkylating moiety and a thiazole ring as isosteric replacement for a carboxamide, are readily synthesized (gram-scale), exhibit defined solid-state structures, and enhanced growth-inhibitory activity against human tumor cell lines, including MGMT-expressing and MMR-deficient lines, molecular features that confer tumor resistance. The cell proliferation data were confirmed by clonogenic cell survival assays, and DNA flow cytometry analysis was undertaken to determine the effects of new analogues on cell cycle progression. Detailed 1H NMR spectroscopic studies showed that the new agents are stable in solution, and confirmed their mechanism of action. The propargyl and thiazole substituents significantly improve potency and physicochemical, drug metabolism and permeability properties, suggesting that the thiazole 13 should be prioritized for further preclinical evaluation.

Inference and reconstruction of the heimdallarchaeial ancestry of eukaryotes.

In the ongoing debates about eukaryogenesis-the series of evolutionary events leading to the emergence of the eukaryotic cell from prokaryotic ancestors-members of the Asgard archaea play a key part as the closest archaeal relatives of eukaryotes1. However, the nature and phylogenetic identity of the last common ancestor of Asgard archaea and eukaryotes remain unresolved2-4. Here we analyse distinct phylogenetic marker datasets of an expanded genomic sampling of Asgard archaea and evaluate competing evolutionary scenarios using state-of-the-art phylogenomic approaches. We find that eukaryotes are placed, with high confidence, as a well-nested clade within Asgard archaea and as a sister lineage to Hodarchaeales, a newly proposed order within Heimdallarchaeia. Using sophisticated gene tree and species tree reconciliation approaches, we show that analogous to the evolution of eukaryotic genomes, genome evolution in Asgard archaea involved significantly more gene duplication and fewer gene loss events compared with other archaea. Finally, we infer that the last common ancestor of Asgard archaea was probably a thermophilic chemolithotroph and that the lineage from which eukaryotes evolved adapted to mesophilic conditions and acquired the genetic potential to support a heterotrophic lifestyle. Our work provides key insights into the prokaryote-to-eukaryote transition and a platform for better understanding the emergence of cellular complexity in eukaryotic cells.

Autoimmune hepatitis presenting with concomitant chronic pancreatitis.

Autoimmune Hepatitis (AIH) is a progressive form of chronic hepatitis, with periods of remissions and exacerbations. Diagnosis includes abnormally high levels of immunoglobulins and multiple autoantibodies. Clinical presentation is variable, with a spectrum extending from asymptomatic cases to fulminant liver failure. Symptoms include abdominal pain, malaise, fatigue, and small joint arthralgia. We present a case of a 36-year-old male with a past medical history of alcohol dependence and acute pancreatitis who was diagnosed with AIH. There is limited data regarding patients with concomitant AIH and pancreatitis. Our patient presented with AIH with secondary acute on chronic pancreatitis, in the absence of additional autoimmune manifestations. The mechanism of AIH remains poorly understood; however, there is an association between the HLA gene and AIH. Genetic studies have shown HLA-DRB1*0301 and HLA-DRB1*0401 as primary and secondary genotypes susceptible to AIH, as well as genetic variants with CARD10 and SH2B3. Products secondary to metabolism of ETOH such as alcohol dehydrogenase, malondialdehyde, and acetaldehyde, can lead to development of autoantibodies. Additional research is indicated to evaluate the relationship between AIH and acute pancreatitis.

Climate-mediated population dynamics of a migratory songbird differ between the trailing edge and range core.

Understanding the demographic drivers of range contractions is important for predicting species' responses to climate change; however, few studies have examined the effects of climate change on survival and recruitment across species' ranges. We show that climate change can drive trailing edge range contractions through the effects on apparent survival, and potentially recruitment, in a migratory songbird. We assessed the demographic drivers of trailing edge range contractions using a long-term demography dataset for the black-throated blue warbler (Setophaga caerulescens) collected across elevational climate gradients at the trailing edge and core of the breeding range. We used a Bayesian hierarchical model to estimate the effect of climate change on apparent survival and recruitment and to forecast population viability at study plots through 2040. The trailing edge population at the low-elevation plot became locally extinct by 2017. The local population at the mid-elevation plot at the trailing edge gradually declined and is predicted to become extirpated by 2040. Population declines were associated with warming temperatures at the mid-elevation plot, although results were more equivocal at the low-elevation plot where we had fewer years of data. Population density was stable or increasing at the range core, although warming temperatures are predicted to cause population declines by 2040 at the low-elevation plot. This result suggests that even populations within the geographic core of the range are vulnerable to climate change. The demographic drivers of local population declines varied between study plots, but warming temperatures were frequently associated with declining rates of population growth and apparent survival. Declining apparent survival in our study system is likely to be associated with increased adult emigration away from poor-quality habitats. Our results suggest that demographic responses to warming temperatures are complex and dependent on local conditions and geographic range position, but spatial variation in population declines is consistent with the climate-mediated range shift hypothesis. Local populations of black-throated blue warblers near the warm-edge range boundary at low latitudes and low elevations are likely to be the most vulnerable to climate change, potentially leading to local extirpation and range contractions.

Epidermal Growth Factor Receptor Inhibitor-Induced Symmetrical Drug-Related Intertriginous and Flexural Exanthema: Should You Discontinue the Offending Agent?

Epidermal growth factor receptor (EGFR) inhibitors cause numerous cutaneous adverse events (AEs), including papulopustular eruptions, paronychia, acral fissures, xerosis, alopecia, and trichomegaly. Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) is a cutaneous reaction that has been uncommonly reported in association with EGFR inhibitors, though the optimal management strategy for this condition is unknown. We present 2 cases of SDRIFE secondary to EGFR inhibitor therapy in which the EGFR inhibitor was successfully continued while topical therapy was administered for effective control of symptoms. We also review the literature on EGFR inhibitor-related SDRIFE to assess the range of approaches to treating this condition. Our analysis suggests that the dermatologist is critical in diagnosing and treating this cutaneous AE, which may be supported with skin-directed therapy and may not require discontinuation of cancer treatment.

Reciprocal discoidin domain receptor signaling strengthens integrin adhesion to connect adjacent tissues.

Separate tissues connect through adjoining basement membranes to carry out molecular barrier, exchange, and organ support functions. Cell adhesion at these connections must be robust and balanced to withstand independent tissue movement. Yet, how cells achieve synchronized adhesion to connect tissues is unknown. Here, we have investigated this question using the C. elegans utse-seam tissue connection that supports the uterus during egg-laying. Through genetics, quantitative fluorescence, and cell specific molecular disruption, we show that type IV collagen, which fastens the linkage, also activates the collagen receptor discoidin domain receptor 2 (DDR-2) in both the utse and seam. RNAi depletion, genome editing, and photobleaching experiments revealed that DDR-2 signals through LET-60/Ras to coordinately strengthen an integrin adhesion in the utse and seam that stabilizes their connection. These results uncover a synchronizing mechanism for robust adhesion during tissue connection, where collagen both affixes the linkage and signals to both tissues to bolster their adhesion.

A potent fluorescent transmembrane HCl transporter perturbs cellular pH and promotes cancer cell death.

A series of fluorescent coumarin bis-ureas 1-4 have been synthesised, and their anion transport properties studied. The compounds function as highly potent HCl co-transport agents in lipid bilayer membranes. Single crystal X-ray diffraction of compound 1 showed antiparallel stacking of the coumarin rings, stabilised by hydrogen bonds. Binding studies, using 1H-NMR titration, showed moderate chloride binding in DMSO-d6/0.5% with 1 : 1 binding mode (for transporter 1) and 1 : 2 binding mode (host: guest, for transporters 2-4). We examined the cytotoxicity of compounds 1-4 against three cancer cell lines, lung adenocarcinoma (A549), colon adenocarcinoma (SW620) and breast adenocarcinoma (MCF-7). The most lipophilic transporter, 4 showed a cytotoxic effect against all three cancer cell lines. Cellular fluorescence studies showed compound 4 crossed the plasma membrane and localised in the cytoplasm after a short time. Interestingly, compound 4, lacking any lysosome targeting groups, was co-localised with LysoTracker Red at 4 and 8 h in the lysosome. Cellular anion transport of compound 4 was assessed by measuring intracellular pH and showed a decrease in cellular pH, which may be due to the capacity of transporter 4 to co-transport HCl across biological membranes, as evidenced by the liposomal studies.

Metronidazole induced cerebellar toxicity after prolonged treatment of large multiloculated pyogenic liver abscess; A case report and literature review.

Metronidazole is a common antibiotic agent for hepatic abscesses, which require both gram-negative and anaerobic coverage. Rarely, this antibiotic has been found to induce encephalopathy. Here, we describe a 65-year-old male who was treated with metronidazole for his hepatic abscess, who presented with syncope and questionable seizure and was found to have magnetic resonance imaging (MRI) brain findings consistent with metronidazole toxicity. Our patient demonstrated striking brain MRI findings which can be used to further understand the process behind this medication-induced toxicity. Hypotheses of this mechanism include swelling of axons secondary to increased water or vasospasm leading to reversible ischemia that is localized in the brain. In terms of MRI findings, brain lesions tend to populate bilaterally with focus at the dorsal pons, midbrain, cerebellar dentate nuclei (as with our patient), dorsal medulla, or splenium of corpus callosum. Additional research is warranted regarding this rare manifestation and timely removal of the offending agent is crucial for reversal of symptoms.

Hemicentin-mediated type IV collagen assembly strengthens juxtaposed basement membrane linkage.

Basement membrane (BM) matrices surround and separate most tissues. However, through poorly understood mechanisms, BMs of adjacent tissue can also stably link to support organ structure and function. Using endogenous knock-in fluorescent proteins, conditional RNAi, optogenetics, and quantitative live imaging, we identified extracellular matrix proteins mediating a BM linkage (B-LINK) between the uterine utse and epidermal seam cell BMs in Caenorhabditis elegans that supports the uterus during egg-laying. We found that hemicentin is secreted by the utse and promotes fibulin-1 assembly to jointly initiate the B-LINK. During egg-laying, however, both proteins' levels decline and are not required for B-LINK maintenance. Instead, we discovered that hemicentin recruits ADAMTS9/20, which facilitates the assembly of high levels of type IV collagen that sustains the B-LINK during the mechanically active egg-laying period. This work reveals mechanisms underlying BM-BM linkage maturation and identifies a crucial function for hemicentin and fibulin-1 in initiating attachment and type IV collagen in strengthening this specialized form of tissue linkage.

Two-step spin crossover by guest-disorder induced local symmetry breaking within a 3D Hofmann-like framework.

A 3D Hofmann-like metal-organic framework has been prepared which contains a 2,1,3-benzothiadiazole-based pillaring ligand. Encapsulation of a polycyclic aromatic hydrocarbon, chrysene, within the pore structure leads to a new pathway to multi-step spin crossover behaviour in which the observed two-step spin transition arises due to the presence of multiple site environments associated with local guest positional effects within the host lattice.

Slow magnetic relaxation in Fe(II) m-terphenyl complexes.

Two-coordinate transition metal complexes are exciting candidates for single-molecule magnets (SMMs) because their highly axial coordination environments lead to sizeable magnetic anisotropy. We report a series of five structurally related two-coordinate Fe(II) m-terphenyl complexes (4-R-2,6-Xyl2C6H2)2Fe [R = tBu (1), SiMe3 (2), H (3), Cl (4), CF3 (5)] where, by changing the functionalisation of the para-substituent (R), we alter their magnetic function. All five complexes are field-induced single-molecule magnets, with relaxation rates that are well-described by a combination of direct and Raman mechanisms. By using more electron donating R groups we were able to slow the rate of magnetic relaxation. Our ab initio calculations predict a large crystal field splitting (>850 cm-1) and sizeable zero-field splitting parameters (ca. -60 cm-1, |E| < 0.2 cm-1) for 1-5. These favourable magnetic properties suggest that m-terphenyl ligands have untapped potential as chemically versatile ligands able to impose highly axial crystal fields.