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Neuronal senescence is a major risk factor for the development of many neurodegenerative disorders. The mechanisms that drive neurons to senescence remain largely elusive; however, dysregulated mitochondrial physiology seems to play a pivotal role in this process. Consequently, strategies aimed to preserve mitochondrial function may hold promise in mitigating neuronal senescence. For example, dietary restriction has shown to reduce senescence, via a mechanism that still remains far from being totally understood, but that could be at least partially mediated by mitochondria. Here, we address the role of mitochondrial inorganic polyphosphate (polyP) in the intersection between neuronal senescence and dietary restriction. PolyP is highly present in mammalian mitochondria; and its regulatory role in mammalian bioenergetics has already been described by us and others. Our data demonstrate that depletion of mitochondrial polyP exacerbates neuronal senescence, independently of whether dietary restriction is present. However, dietary restriction in polyP‐depleted cells activates AMPK, and it restores some components of mitochondrial physiology, even if this is not sufficient to revert increased senescence. The effects of dietary restriction on polyP levels and AMPK activation are conserved in differentiated SH‐SY5Y cells and brain tissue of male mice. Our results identify polyP as an important component in mitochondrial physiology at the intersection of dietary restriction and senescence, and they highlight the importance of the organelle in this intersection. [ABSTRACT FROM AUTHOR]

Synaptic connectivity and molecular composition provide a blueprint for information processing in neural circuits. Detailed structural analysis of neural circuits requires nanometer resolution, which can be obtained with serial-section electron microscopy. However, this technique remains challenging for reconstructing molecularly defined synapses. We used a genetically encoded synaptic marker for electron microscopy (GESEM) based on intra-vesicular generation of electron-dense labeling in axonal boutons. This approach allowed the identification of synapses from Cre recombinase-expressing or GAL4-expressing neurons in the mouse and fly with excellent preservation of ultrastructure. We applied this tool to visualize long-range connectivity of AGRP and POMC neurons in the mouse, two molecularly defined hypothalamic populations that are important for feeding behavior. Combining selective ultrastructural reconstruction of neuropil with functional and viral circuit mapping, we characterized some basic features of circuit organization for axon projections of these cell types. Our findings demonstrate that GESEM labeling enables long-range connectomics with molecularly defined cell types.

In April 2023, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), in partnership with the National Institute of Child Health and Human Development, the National Institute on Aging, and the Office of Behavioral and Social Sciences Research, hosted a 2‐day online workshop to discuss neural plasticity in energy homeostasis and obesity. The goal was to provide a broad view of current knowledge while identifying research questions and challenges regarding neural systems that control food intake and energy balance. This review includes highlights from the meeting and is intended both to introduce unfamiliar audiences with concepts central to energy homeostasis, feeding, and obesity and to highlight up‐and‐coming research in these areas that may be of special interest to those with a background in these fields. The overarching theme of this review addresses plasticity within the central and peripheral nervous systems that regulates and influences eating, emphasizing distinctions between healthy and disease states. This is by no means a comprehensive review because this is a broad and rapidly developing area. However, we have pointed out relevant reviews and primary articles throughout, as well as gaps in current understanding and opportunities for developments in the field. [ABSTRACT FROM AUTHOR]

Hunger involves interoceptive sensory neurons that monitor metabolic signals and consequently regulate food seeking and consumption behaviours. To isolate discrete neural circuit pathways controlling feeding behaviour, we have focused on [...], Hunger is a complex behavioural state that elicits intense food seeking and consumption. These behaviours are rapidly recapitulated by activation of starvation-sensitive AGRP neurons, which present an entry point for reverse-engineering neural circuits for hunger. Here we mapped synaptic interactions of AGRP neurons with multiple cell populations in mice and probed the contribution of these distinct circuits to feeding behaviour using optogenetic and pharmacogenetic techniques. An inhibitory circuit with paraventricular hypothalamus (PVH) neurons substantially accounted for acute AGRP neuron-evoked eating, whereas two other prominent circuits were insufficient. Within the PVH, we found that AGRP neurons target and inhibit oxytocin neurons, a small population that is selectively lost in Prader-Willi syndrome, a condition involving insatiable hunger. By developing strategies for evaluating molecularly defined circuits, we show that AGRP neuron suppression of oxytocin neurons is critical for evoked feeding. These experiments reveal a new neural circuit that regulates hunger state and pathways associated with overeating disorders.

In Xenopus, an early and a late pathway exist for the selective localization of RNAs to the vegetal cortex during oogenesis. Previous work has suggested that distinct cellular mechanisms mediate localization during these pathways. Here, we provide several independent lines of evidence supporting the existence of common machinery for RNA localization during the early and late pathways. Data from RNA microinjection assays show that early and late pathway RNAs compete for common localization factors in vivo, and that the same short RNA sequence motifs are required for localization during both pathways. In addition, quantitative filter binding assays demonstrate that the late localization factor Vg RBP/Vera binds specifically to several early pathway RNA localization elements. Finally, confocal imaging shows that early pathway RNAs associate with a perinuclear microtubule network that connects to the mitochondrial cloud of stage I oocytes suggesting that motor driven transport plays a role during the early pathway as it does during the late pathway. Taken together, our data indicate that common machinery functions during the early and late pathways. Thus, RNA localization to the vegetal cortex may be a regulated process such that differential interactions with basal factors determine when distinct RNAs are localized during oogenesis. Keywords: RNA localization; Xenopus; Oocytes; Vg1 RBP; Vera; Vg1; Xcat-2; KH domain; Microtubules

Author(s): J. Nicholas Betley [1]; Shengjin Xu [1]; Zhen Fang Huang Cao [1]; Rong Gong [1]; Christopher J. Magnus [1]; Yang Yu [1]; Scott M. Sternson (corresponding author) [1] AGRP [...], Homeostasis is a biological principle for regulation of essential physiological parameters within a set range. Behavioural responses due to deviation from homeostasis are critical for survival, but motivational processes engaged by physiological need states are incompletely understood. We examined motivational characteristics of two separate neuron populations that regulate energy and fluid homeostasis by using cell-type-specific activity manipulations in mice. We found that starvation-sensitive AGRP neurons exhibit properties consistent with a negative-valence teaching signal. Mice avoided activation of AGRP neurons, indicating that AGRP neuron activity has negative valence. AGRP neuron inhibition conditioned preference for flavours and places. Correspondingly, deep-brain calcium imaging revealed that AGRP neuron activity rapidly reduced in response to food-related cues. Complementary experiments activating thirst-promoting neurons also conditioned avoidance. Therefore, these need-sensing neurons condition preference for environmental cues associated with nutrient or water ingestion, which is learned through reduction of negative-valence signals during restoration of homeostasis.

The brain regulates food intake by processing sensory cues and peripheral physiological signals, but the neural basis of this integration remains unclear. Hypothalamic, agouti-related protein (AgRP)-expressing neurons are critical regulators of food intake. AgRP neuron activity is high during hunger and is rapidly reduced by the sight and smell of food. Here, we reveal two distinct components of AgRP neuron activity regulation: a rapid but transient sensory-driven signal and a slower, sustained calorie- dependent signal. We discovered that nutrients are necessary and sufficient for sustained reductions in AgRP neuron activity and that activity reductions are proportional to the calories obtained. This change in activity is recapitulated by exogenous administration of gut-derived satiation signals. Furthermore, we showed that the nutritive value of food trains sensory systems-in a single trial-to drive rapid, anticipatory AgRP neuron activity inhibition. Together, these data demonstrate that nutrients are the primary regulators of AgRP neuron activity. [ABSTRACT FROM AUTHOR]

During oogenesis in Xenopus laevis, several RNAs that localize to the vegetal cortex via one of three temporally defined pathways have been identified . Although individual mRNAs utilize only one pathway, there is functional overlap and apparent continuity between them, suggesting that common cis-acting sequences may exist. Because previous work with the Vg1 mRNA revealed that short nontandem repeats are important for localization , we developed a new computer program, called REPFIND, to expedite the identification of repeated motifs in other localized RNAs. Here we show that clusters of short CAC-containing motifs characterize the localization elements (LEs) of virtually all mRNAs localized to the vegetal cortex of Xenopus oocytes. A search for this signal in GenBank [9] resulted in the identification of new localized mRNAs, demonstrating the applicability of REPFIND to predict localized RNAs. CAC-rich LEs are also found in ascidians and other vertebrates, indicating that these cis regulatory elements are conserved in chordates. Interestingly, biochemical evidence shows that distinct CAC-containing motifs have different functions in the localization process. Thus, clusters of CAC-containing motifs are a ubiquitous signal for RNA localization and can signal localization in a variety of pathways through slight variations in sequence composition. [Copyright &y& Elsevier]

Long-term sustained pain in the absence of acute physical injury is a prominent feature of chronic pain conditions. While neurons responding to noxious stimuli have been identified, understanding the signals that persist without ongoing painful stimuli remains a challenge. Using an ethological approach based on the prioritization of adaptive survival behaviors, we determined that neuropeptide Y (NPY) signaling from multiple sources converges on parabrachial neurons expressing the NPY Y1 receptor to reduce sustained pain responses. Neural activity recordings and computational modeling demonstrate that activity in Y1R parabrachial neurons is elevated following injury, predicts functional coping behavior, and is inhibited by competing survival needs. Taken together, our findings suggest that parabrachial Y1 receptor-expressing neurons are a critical hub for endogenous analgesic pathways that suppress sustained pain states.

Deep sequencing of B cell receptor (BCR) heavy chains from a cohort of 31 COVID-19 patients from the UK reveals a stereotypical naive immune response to SARS-CoV-2 which is consistent across patients. Clonal expansion of the B cell population is also observed and may be the result of memory bystander effects. There was a strong convergent sequence signature across patients, and we identified 1,254 clonotypes convergent between at least four of the COVID-19 patients, but not present in healthy controls or individuals following seasonal influenza vaccination. A subset of the convergent clonotypes were homologous to known SARS and SARS-CoV-2 spike protein neutralizing antibodies. Convergence was also demonstrated across wide geographies by comparison of data sets between patients from UK, USA, and China, further validating the disease association and consistency of the stereotypical immune response even at the sequence level. These convergent clonotypes provide a resource to identify potential therapeutic and prophylactic antibodies and demonstrate the potential of BCR profiling as a tool to help understand patient responses., Competing Interests: JO, AL, OC, SS, JG, JD, RM, and DF are employees of Alchemab Therapeutics Limited. RB-R is a founder of and consultant to Alchemab Therapeutics Limited. GK is a consultant to Alchemab Therapeutics Limited. CC is a member of the AstraZeneca External Science Panel and has research grants from Roche, Genentech, AstraZeneca, and Servier that are administered by the University of Cambridge. JB was employed by Illumina, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Galson, Schaetzle, Bashford-Rogers, Raybould, Kovaltsuk, Kilpatrick, Minter, Finch, Dias, James, Thomas, Lee, Betley, Cavlan, Leech, Deane, Seoane, Caldas, Pennington, Pfeffer and Osbourn.)

There is growing evidence for the value of bacterial whole-genome sequencing in hospital outbreak investigations. Our aim was to develop methods that support efficient and accurate low-throughput clinical sequencing of methicillin-resistant Staphylococcus aureus (MRSA) isolates. Using a test panel of 25 MRSA isolates previously associated with outbreak investigations, we devised modifications to library preparation that reduced the processing time by 1 hour. We determined the maximum number of isolates that could be sequenced per run using an Illumina MiniSeq platform and a 13-hour (overnight) run time, which equated to 21 MRSA isolates and 3 controls (no template, positive, and negative). Repeatability and reproducibility assays based on this sequencing methodology demonstrated 100% accuracy in assigning species and sequence type (ST) and in detecting mecA Established genetic relatedness between isolates was recapitulated. Quality control (QC) metrics were evaluated over nine sequencing runs. Of the test panel MRSA genomes, 168/173 (97%) passed QC metrics based on the correct species assigned, detection of mecA and ST, and depth/coverage metrics. An evaluation of contamination in these 9 runs showed that positive and negative controls and test MRSA sequence files contained <0.14% and <0.48% of fragments that matched another species, respectively. Deliberate contamination experiments confirmed that this was insufficient to impact data interpretation. These methods support reliable and reproducible clinical MRSA sequencing with a turnaround time (from DNA extraction to availability of data files) of 24 hours., (Copyright © 2019 Raven et al.)

Background: Recent evidence suggests that hospital transmission of methicillin-resistant Staphylococcus aureus (MRSA) is uncommon in UK centers that have implemented sustained infection control programs. We investigated whether a healthcare-network analysis could shed light on transmission paths currently sustaining MRSA levels in UK hospitals., Methods: A cross-sectional observational study was performed in 2 National Health Service hospital groups and a general district hospital in Southeast London. All MRSA patients identified at inpatient, outpatient, and community settings between 1 November 2011 and 29 February 2012 were included. We identified genetically defined MRSA transmission clusters in individual hospitals and across the healthcare network, and examined genetic differentiation of sequence type (ST) 22 MRSA isolates within and between hospitals and inpatient or outpatient and community settings, as informed by average and median pairwise single-nucleotide polymorphisms (SNPs) and SNP-based proportions of nearly identical isolates., Results: Two hundred forty-eight of 610 (40.7%) MRSA patients were linked in 90 transmission clusters, of which 27 spanned multiple hospitals. Analysis of a large 32 patient ST22-MRSA cluster showed that 26 of 32 patients (81.3%) had multiple contacts with one another during ward stays at any hospital. No residential, outpatient, or significant community healthcare contacts were identified. Genetic differentiation between ST22 MRSA inpatient isolates from different hospitals was less than between inpatient isolates from the same hospitals (P ≤ .01)., Conclusions: There is evidence of frequent ward-based transmission of MRSA brought about by frequent patient admissions to multiple hospitals. Limiting in-ward transmission requires sharing of MRSA status data between hospitals., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Oral iron administration in African children can increase the risk for infections. However, it remains unclear to what extent supplementary iron affects the intestinal microbiome. We here explored the impact of iron preparations on microbial growth and metabolism in the well-controlled TNO's in vitro model of the large intestine (TIM-2). The model was inoculated with a human microbiota, without supplementary iron, or with 50 or 250 μmol/L ferrous sulfate, 50 or 250 μmol/L ferric citrate, or 50 μmol/L hemin. High resolution responses of the microbiota were examined by 16S rDNA pyrosequencing, microarray analysis, and metagenomic sequencing. The metabolome was assessed by fatty acid quantification, gas chromatography-mass spectrometry (GC-MS), and (1)H-NMR spectroscopy. Cultured intestinal epithelial Caco-2 cells were used to assess fecal water toxicity. Microbiome analysis showed, among others, that supplementary iron induced decreased levels of Bifidobacteriaceae and Lactobacillaceae, while it caused higher levels of Roseburia and Prevotella. Metagenomic analyses showed an enrichment of microbial motility-chemotaxis systems, while the metabolome markedly changed from a saccharolytic to a proteolytic profile in response to iron. Branched chain fatty acids and ammonia levels increased significantly, in particular with ferrous sulfate. Importantly, the metabolite-containing effluent from iron-rich conditions showed increased cytotoxicity to Caco-2 cells. Our explorations indicate that in the absence of host influences, iron induces a more hostile environment characterized by a reduction of microbes that are generally beneficial, and increased levels of bacterial metabolites that can impair the barrier function of a cultured intestinal epithelial monolayer.