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Abstract While significant advances have been made in understanding renal pathophysiology, less is known about the role of glycosphingolipid (GSL) metabolism in driving organ dysfunction. Here, we used a small molecule inhibitor of glucosylceramide synthase to modulate GSL levels in three mouse models of distinct renal pathologies: Alport syndrome (Col4a3 KO), polycystic kidney disease (Nek8 jck ), and steroid-resistant nephrotic syndrome (Nphs2 cKO). At the tissue level, we identified a core immune-enriched transcriptional signature that was shared across models and enriched in human polycystic kidney disease. Single nuclei analysis identified robust transcriptional changes across multiple kidney cell types, including epithelial and immune lineages. To further explore the role of GSL modulation in macrophage biology, we performed in vitro studies with homeostatic and inflammatory bone marrow-derived macrophages. Cumulatively, this study provides a comprehensive overview of renal dysfunction and the effect of GSL modulation on kidney-derived cells in the setting of renal dysfunction.

(1) Background: Breathing is an essential function that requires both metabolic (or au-tomatic) and voluntary (behavioral) control during wakefulness but during sleep depends on metabolic control via peripheral and central chemoreceptors. Breathing during sleep disordered breathing also depends on the maturity of the neural centers and the strength of the respiratory muscles. We do not know if the response to apnea varies with age. (2) Methods: We measured the obstructive apneas and hypopneas during REM and NREM in polysomnography studies from children referred for snoring. Exclusion criteria: younger than 1 year of age, neuromuscular or syndrome comorbidity, oxygen or positive airway pressure, central apnea, and studies with loss of airflow sensors. (3) Results: Two-hundred-and-sixty-eight sleep studies were included. Mean age was 8.7 years (4.68 SD), range 1-18 years, 160 were male, and 108 were female. The 5th centile of apnea duration during NREM is above 8 s at all ages, with a tendency to increase in the oldest groups up to 10 s. During REM sleep, it shows a gradual increase from 6 s in the youngest children to 10 s in the oldest. (4) Conclusions: Apnea/hypopnea length increases with age in children and adolescents independently from sex or severity of OSA. Using adult criteria in teens seems to be accurate.

We examined the performance of sweetgum (Liquidambar styraciflua L.), cherrybark oak (Quercus pagoda Raf.), and loblolly pine (Pinus taeda L.) in two-species pine-hardwood mixtures (sweetgum : loblolly pine and cherrybark oak : loblolly pine) at various planting densities (1482-1976 trees per hectare (TPH)) over 23 years in northern Louisiana, USA. Species were planted in alternating rows with hardwood establishment occurring 1 year prior to loblolly pine. Mixtures were also compared to loblolly pine monocultures at a common density (1482 TPH) to assess whether mixing improved productivity. Sweetgum exerted more competitive pressure on loblolly pine than cherrybark oak. At final measurement, sweetgum survival statistically exceeded that of loblolly pine across mixture density. Moreover, sweetgum cumulative basal area and volume growth nearly tripled that of loblolly pine in balanced high-density mixtures (1976 TPH, 50 pine : 50 hardwood). In contrast, cherrybark oak basal area and volume growth did not significantly exceed loblolly pine at any density. At a common density (1482 TPH), loblolly pine monoculture cumulative basal area and volume significantly exceeded those of mixtures with sweetgum and cherrybark oak by 19% and 24%, respectively. Collectively, these results indicate that growing loblolly pine in mixture with these two species did not produce complementary interactions and negatively affected stand-level growth. Key words: overyielding, loblolly pine, cherrybark oak, sweetgum, interspecific competition, mixed stands Nous avons examine la performance du copalme d'Amerique (Liquidambar styraciflua L.), du chene a feuilles en pagode (Quercus pagoda Raf.) et du pin a encens (Pinus taeda L.) dans des melanges de pins et de feuillus a deux especes (copalme d'Amerique : pin a encens et chene a feuilles en pagode : pin a encens) a diverses densites de plantation (1482 a 1976 TPH) pendant 23 ans dans le nord de la Louisiane, aux Etats-Unis. Les especes ont ete plantees en rangs alternes, l'etablissement des feuillus ayant lieu un an avant celui des pins a encens. Les melanges ont egalement ete compares aux monocultures de pin a encens a une densite commune (1482 TPH) pour evaluer si le melange ameliorait la productivite. Le copalme d'Amerique a exerce une plus grande pression concurrentielle sur le pin a encens que le chene a feuilles en pagode. Lors de la mesure finale, la survie du copalme d'Amerique a statistiquement depasse celle du pin a encens, quelle que soit la densite du melange. De plus, la croissance cumulative de la zone basale et du volume du copalme d'Amerique a presque triple par rapport a celle du pin a encens dans les melanges equilibres a haute densite (1976 TPH, 50 pins : 50 feuillus). En revanche, la croissance de la surface terriere et du volume du chene a feuilles en pagode n'a pas depasse de maniere significative celle du pin a encens, quelle que soit la densite. A une densite commune (1482 TPH), la zone basale et le volume cumules de la monoculture du pin a encens ont depasse de maniere significative ceux des melanges avec le copalme d'Amerique et le chene a feuilles en pagode de 19% et 24%, respectivement. Collectivement, ces resultats indiquent que la culture du pin a encens en melange avec ces deux especes n'a pas produit d'interactions complementaires et a affecte negativement la croissance au niveau du peuplement. [Traduit par la Redaction] Mots-cles : rendement excessif, pin a encens, chene a feuilles en pagode, copalme d'Amerique, competition interspecifique, peuplements mixtes, Introduction Maintaining productive forests is a global priority. Historically, monocultures have been established to maximize forest productivity (Rubilar et al. 2018). However, concerns over declining biodiversity, enhanced risk of species-specific [...]

Abstract Tau accumulation and progressive loss of neurons are associated with Alzheimer’s disease (AD). Aggregation of tau has been associated with endoplasmic reticulum (ER) stress and the activation of the unfolded protein response (UPR). While ER stress and the UPR have been linked to AD, the contribution of these pathways to tau-mediated neuronal death is still unknown. We tested the hypothesis that reducing C/EBP Homologous Protein (CHOP), a UPR induced transcription factor associated with cell death, would mitigate tau-mediated neurotoxicity through the ER stress pathway. To evaluate this, 8.5-month-old male rTg4510 tau transgenic mice were injected with a CHOP-targeting or scramble shRNA AAV9 that also expressed EGFP. Following behavioral assessment, brain tissue was collected at 12 months, when ER stress and neuronal loss is ongoing. No behavioral differences in locomotion, anxiety-like behavior, or learning and memory were found in shCHOP mice. Unexpectedly, mice expressing shCHOP had higher levels of CHOP, which did not affect neuronal count, UPR effector (ATF4), or tau tangles. Overall, this suggests that CHOP is a not a main contributor to neuronal death in rTg4510 mice. Taken together with previous studies, we conclude that ER stress, including CHOP upregulation, does not worsen outcomes in the tauopathic brain.

Microorganisms thrive nearly everywhere including extreme environments where few other forms of life can exist. Geochemistry of extreme sites plays a major role in shaping these microbial communities and microbes thriving in such harsh conditions are untapped sources of novel biomolecules. To understand the structure and composition of such microbial communities, culture-independent bacterial diversity was characterised for two extreme sites in Pakistan, Khewra salt range and Murtazaabad hot spring. Barcoded amplicon sequencing technique was used to study the microbial communities. Physicochemical analysis of these sites was also conducted to study the dynamics of microbial communities under stressed conditions. Metagenomic sequencing of salt range soil samples yielded of 40,433 16S rRNA sequences, while hot spring sediments produced 76,449 16S rRNA sequence reads. Proteobacteria were predominant in saline soil while Firmicutes were most abundant in hot spring sediment. The taxonomic analysis of saline samples revealed 914 operational taxonomic units (OTUs) while that of hot spring sequences were clustered into 726 distinct OTUs. OTUs from genus Alkalibacillus were most abundant in hot spring sediments, whereas Haloarcula were more prevalent in saline soil. Some unidentified sequences were also present at each taxonomic level. Multivariate analysis indicated that electrical conductivity and pH are the major environmental factors involved in modelling microbial communities. This study revealed a poly-extremophilic microbial community in the Murtazaabad hot spring and characterised the unexplored halophilic microbial diversity of saline soil of Pakistan.

Abstract Abnormal accumulation of hyperphosphorylated tau induces pathogenesis in neurodegenerative diseases, like Alzheimer’s disease. Molecular chaperones with peptidyl-prolyl cis/trans isomerase (PPIase) activity are known to regulate these processes. Previously, in vitro studies have shown that the 52 kDa FK506-binding protein (FKBP52) interacts with tau inducing its oligomerization and fibril formation to promote toxicity. Thus, we hypothesized that increased expression of FKBP52 in the brains of tau transgenic mice would alter tau phosphorylation and neurofibrillary tangle formation ultimately leading to memory impairments. To test this, tau transgenic (rTg4510) and wild-type mice received bilateral hippocampal injections of virus overexpressing FKBP52 or GFP control. We examined hippocampal-dependent memory, synaptic plasticity, tau phosphorylation status, and neuronal health. This work revealed that rTg4510 mice overexpressing FKBP52 had impaired spatial learning, accompanied by long-term potentiation deficits and hippocampal neuronal loss, which was associated with a modest increase in total caspase 12. Together with previous studies, our findings suggest that FKBP52 may sensitize neurons to tau-mediated dysfunction via activation of a caspase-dependent pathway, contributing to memory and learning impairments.

Abstract The microtubule associated protein tau is an intrinsically disordered phosphoprotein that accumulates under pathological conditions leading to formation of neurofibrillary tangles, a hallmark of Alzheimer’s disease (AD). The mechanisms that initiate the accumulation of phospho-tau aggregates and filamentous deposits are largely unknown. In the past, our work and others’ have shown that molecular chaperones play a crucial role in maintaining protein homeostasis and that imbalance in their levels or activity can drive tau pathogenesis. We have found two co-chaperones of the 90 kDa heat shock protein (Hsp90), FK506-binding protein 52 (FKBP52) and the activator of Hsp90 ATPase homolog 1 (Aha1), promote tau aggregation in vitro and in the brains of tau transgenic mice. Based on this, we hypothesized that increased levels of these chaperones could promote tau misfolding and accumulation in the brains of aged wild-type mice. We tested this hypothesis by overexpressing Aha1, FKBP52, or mCherry (control) proteins in the hippocampus of 9-month-old wild-type mice. After 7 months of expression, mice were evaluated for cognitive and pathological changes. Our results show that FKBP52 overexpression impaired spatial reversal learning, while Aha1 overexpression impaired associative learning in aged wild-type mice. FKBP52 and Aha1 overexpression promoted phosphorylation of distinct AD-relevant tau species. Furthermore, FKBP52 activated gliosis and promoted neuronal loss leading to a reduction in hippocampal volume. Glial activation and phospho-tau accumulation were also detected in areas adjacent to the hippocampus, including the entorhinal cortex, suggesting that after initiation these pathologies can propagate through other brain regions. Overall, our findings suggest a role for chaperone imbalance in the initiation of tau accumulation in the aging brain.

The microtubule-associated protein tau pathologically accumulates and aggregates in Alzheimer’s disease (AD) and other tauopathies, leading to cognitive dysfunction and neuronal loss. Molecular chaperones, like small heat-shock proteins (sHsps), can help deter the accumulation of misfolded proteins, such as tau. Here, we tested the hypothesis that the overexpression of wild-type Hsp22 (wtHsp22) and its phosphomimetic (S24,57D) Hsp22 mutant (mtHsp22) could slow tau accumulation and preserve memory in a murine model of tauopathy, rTg4510. Our results show that Hsp22 protected against deficits in synaptic plasticity and cognition in the tauopathic brain. However, we did not detect a significant change in tau phosphorylation or levels in these mice. This led us to hypothesize that the functional benefit was realized through the restoration of dysfunctional pathways in hippocampi of tau transgenic mice since no significant benefit was measured in non-transgenic mice expressing wtHsp22 or mtHsp22. To identify these pathways, we performed mass spectrometry of tissue lysates from the injection site. Overall, our data reveal that Hsp22 overexpression in neurons promotes synaptic plasticity by regulating canonical pathways and upstream regulators that have been characterized as potential AD markers and synaptogenesis regulators, like EIF4E and NFKBIA.

An amendment to this paper has been published and can be accessed via the original article.

(1) Background: Breathing is an essential function that requires both metabolic (or au-tomatic) and voluntary (behavioral) control during wakefulness but during sleep depends on metabolic control via peripheral and central chemoreceptors. Breathing during sleep disordered breathing also depends on the maturity of the neural centers and the strength of the respiratory muscles. We do not know if the response to apnea varies with age. (2) Methods: We measured the obstructive apneas and hypopneas during REM and NREM in polysomnography studies from children referred for snoring. Exclusion criteria: younger than 1 year of age, neuromuscular or syndrome comorbidity, oxygen or positive airway pressure, central apnea, and studies with loss of airflow sensors. (3) Results: Two-hundred-and-sixty-eight sleep studies were included. Mean age was 8.7 years (4.68 SD), range 1–18 years, 160 were male, and 108 were female. The 5th centile of apnea duration during NREM is above 8 s at all ages, with a tendency to increase in the oldest groups up to 10 s. During REM sleep, it shows a gradual increase from 6 s in the youngest children to 10 s in the oldest. (4) Conclusions: Apnea/hypopnea length increases with age in children and adolescents independently from sex or severity of OSA. Using adult criteria in teens seems to be accurate.

Targeting virulence rather than bacterial growth is less likely to select for antibiotic resistance, but many possible targets function in both processes. Here, the authors reconstruct a genome-scale metabolic network ofP. aeruginosastrain PA14 and update that of strain PAO1, which, together with mutant screens, enable them to identify genes uniquely critical for virulence factor production.

The identification of genes essential for bacterial growth and survival represents a promising strategy for the discovery of antimicrobial targets. Essential genes can be identified on a genome-scale using transposon mutagenesis approaches; however, variability between screens and challenges with interpretation of essentiality data hinder the identification of both condition-independent and condition-dependent essential genes. To illustrate the scope of these challenges, we perform a large-scale comparison of multiple published Pseudomonas aeruginosa gene essentiality datasets, revealing substantial differences between the screens. We then contextualize essentiality using genome-scale metabolic network reconstructions and demonstrate the utility of this approach in providing functional explanations for essentiality and reconciling differences between screens. Genome-scale metabolic network reconstructions also enable a high-throughput, quantitative analysis to assess the impact of media conditions on the identification of condition-independent essential genes. Our computational model-driven analysis provides mechanistic insight into essentiality and contributes novel insights for design of future gene essentiality screens and the identification of core metabolic processes.

Misfolding, aggregation and accumulation of proteins are toxic elements in the progression of a broad range of neurodegenerative diseases. Molecular chaperones enable a cellular defense by reducing or compartmentalizing these insults. Small heat shock proteins (sHsps) engage proteins early in the process of misfolding and can facilitate their proper folding or refolding, sequestration, or clearance. Here, we evaluate the effects of the sHsp Hsp22, as well as a pseudophosphorylated mutant and an N-terminal domain deletion (NTDΔ) variant on tau aggregation in vitro and tau accumulation and aggregation in cultured cells. Hsp22 wild-type (WT) protein had a significant inhibitory effect on heparin-induced aggregation in vitro and the pseudophosphorylated mutant Hsp22 demonstrated a similar effect. When co-expressed in a cell culture model with tau, these Hsp22 constructs significantly reduced soluble tau protein levels when transfected at a high ratio relative to tau. However, the Hsp22 NTDΔ protein drastically reduced the soluble protein expression levels of both tau WT and tau P301L/S320F even at lower transfection ratios, which resulted in a correlative reduction of the triton-insoluble tau P301L/S320F aggregates.

Loblolly pine plantations in the western portion of the species’ range are sometimes planted with genotypes from the eastern portion of its range to improve plantation productivity. Advances in loblolly pine breeding have led to the development of clonally propagated genotypes with higher potential growth rates and better form than more commonly planted half-sib genotypes. At a site in the western portion of the loblolly pine range, four genotypes from the eastern portion of the loblolly pine range were established. Two genotypes (HS756 and HS8103) were half-sib, and two genotypes (V9 and V93) were varieties. The V93 genotype was propagated from the HS756 genotype. The objective of this study was to determine the effects of genotype on seasonal trends in gas exchange parameters at the leaf and crown levels, growth, and biomass allocation patterns. During the two-year study, one year had precipitation and temperature trends similar to the long-term average and one year had extreme drought, with record heat. The HS756, V9, and V93 genotypes had the highest height growth throughout the study. The V93 genotype was sensitive to the drought; its leaf- and crown-level Asat and gs, declined during the drought more markedly than those of the other genotypes. Although its Asat and gs were affected by drought, height growth productivity of V93 may have been sustained during the drought by its biomass partitioning pattern of allocating higher proportions of its root biomass to small and fine roots and its aboveground biomass to foliage. These results suggest that a variety such as V93 could be more susceptible to changes in C fixation and water uptake with recurrent drought.