Arc/Arg3.1 mRNA Global Expression Patterns Elicited by Memory Recall in Cerebral Cortex Differ for Remote Versus Recent Spatial Memories

The neocortex plays a critical role in the gradual formation and storage of remote declarative memories. Because the circuitry mechanisms of systems-level consolidation are not well understood, the precise cortical sites for memory storage and the nature of enduring memory correlates (mnemonic plasticity) are largely unknown. Detailed maps of neuronal activity underlying recent and remote memory recall highlight brain regions that participate in systems consolidation and constitute putative storage sites, and thus may facilitate detection of mnemonic plasticity. To localize cortical regions involved in the recall of a spatial memory task, we trained rats in a water-maze and then mapped mRNA expression patterns of a neuronal activity marker Arc/Arg3.1 (Arc) upon recall of recent (24 h after training) or remote (1 month after training) memories and compared them with swimming and naive controls. Arc gene expression was significantly more robust 24 h after training compared to 1 month after training. Arc expression diminished in the parietal, cingulate and visual areas, but select segments in the prefrontal, retrosplenial, somatosensory and motor cortical showed similar robust increases in the Arc expression. When Arc expression was compared across select segments of sensory, motor and associative regions within recent and remote memory groups, the overall magnitude and cortical laminar patterns of task-specific Arc expression were similar (stereotypical). Arc mRNA fractions expressed in the upper cortical layers (2/3, 4) increased after both recent and remote recall, while layer 6 fractions decreased only after the recent recall. The data suggest that robust recall of remote memory requires an overall smaller increase in neuronal activity within fewer cortical segments. This activity trend highlights the difficulty in detecting the storage sites and plasticity underlying remote memory. Application of the Arc maps may ameliorate this difficulty

BHLHE40 regulates the T-cell effector function required for tumor microenvironment remodeling and immune checkpoint therapy efficacy

Immune checkpoint therapy (ICT) using antibody blockade of programmed cell death protein 1 (PD-1) or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) can provoke T cell-dependent antitumor activity that generates durable clinical responses in some patients. The epigenetic and transcriptional features that T cells require for efficacious ICT remain to be fully elucidated. Herein, we report that anti-PD-1 and anti-CTLA-4 ICT induce upregulation of the transcription factor BHLHE40 in tumor antigen-specific CD8+ and CD4+ T cells and that T cells require BHLHE40 for effective ICT in mice bearing immune-edited tumors. Single-cell RNA sequencing of intratumoral immune cells in BHLHE40-deficient mice revealed differential ICT-induced immune cell remodeling. The BHLHE40-dependent gene expression changes indicated dysregulated metabolism, NF-κB signaling, and IFNγ response within certain subpopulations of CD4+ and CD8+ T cells. Intratumoral CD4+ and CD8+ T cells from BHLHE40-deficient mice exhibited higher expression of the inhibitory receptor gene Tigit and displayed alterations in expression of genes encoding chemokines/chemokine receptors and granzyme family members. Mice lacking BHLHE40 had reduced ICT-driven IFNγ production by CD4+ and CD8+ T cells and defects in ICT-induced remodeling of macrophages from a CX3CR1+CD206+ subpopulation to an iNOS+ subpopulation that is typically observed during effective ICT. Although both anti-PD-1 and anti-CTLA-4 ICT in BHLHE40-deficient mice led to the same outcome-tumor outgrowth-several BHLHE40-dependent alterations were specific to the ICT that was used. Our results reveal a crucial role for BHLHE40 in effective ICT and suggest that BHLHE40 may be a predictive or prognostic biomarker for ICT efficacy and a potential therapeutic target

Contrast saturation resonances in the absorption band of rubidium molecules

We study Doppler-free saturation resonances in the absorption band of rubidium diatomic molecules in the frequency range near the D2 line of lithium atoms (671 nm). We observe contrast saturation resonances and record a variation in the laser light transmission of 4% due to optical saturation. The large optical nonlinearities in the molecular diatomic gas can be used for investigating the four-wave mixing and other nonlinear effects

Atomistic Simulations of Coating of Silver Nanoparticles with Poly(vinylpyrrolidone) Oligomers: Effect of Oligomer Chain Length

Silver nanoparticles (AgNPs) possess unique physicochemical properties, which are different from those of matter of the same chemical composition on a larger scale. These features open up the opportunity for their use in many promising chemical and biomedical applications. In this study we have developed an atomistic model for molecular dynamics (MD) simulations of AgNP coated by poly­(<i>N</i>-vinyl-2-pyrrolidone) (PVP) oligomers. We focus on identifying the relative length of PVP oligomers, enabling effective protecting of a crystalline silver core of 4.5 nm diameter from water contacts. Three different PVP-coated AgNP systems have been compared: (i) a nanoparticle coated by a mixture of short-chain PVP oligomers of the varying size and (ii,iii) the silver core wrapped by a single, long-chain PVP polymer with the number of monomers equal to 816 and 1440, respectively. We have validated the MD models of the PVP–AgNPs using a series of MD simulations reproducing adsorption, wrapping, and coating of PVP around a silver core either as short PVP oligomers or as a single-chain, long polymer of a varying length. Our simulations predict that the saturated coating of PVP around the silver core of the given diameter can occur when the polymer chain length approaches 2600–2800 units

Origin and Evolution of Retinoid Isomerization Machinery in Vertebrate Visual Cycle: Hint from Jawless Vertebrates

<div><p>In order to maintain visual sensitivity at all light levels, the vertebrate eye possesses a mechanism to regenerate the visual pigment chromophore <em>11-cis</em> retinal in the dark enzymatically, unlike in all other taxa, which rely on photoisomerization. This mechanism is termed the visual cycle and is localized to the retinal pigment epithelium (RPE), a support layer of the neural retina. Speculation has long revolved around whether more primitive chordates, such as tunicates and cephalochordates, anticipated this feature. The two key enzymes of the visual cycle are RPE65, the visual cycle <em>all-trans</em> retinyl ester isomerohydrolase, and lecithin:retinol acyltransferase (LRAT), which generates RPE65’s substrate. We hypothesized that the origin of the vertebrate visual cycle is directly connected to an ancestral carotenoid oxygenase acquiring a new retinyl ester isomerohydrolase function. Our phylogenetic analyses of the RPE65/BCMO and N1pC/P60 (LRAT) superfamilies show that neither RPE65 nor LRAT orthologs occur in tunicates (<em>Ciona</em>) or cephalochordates (<em>Branchiostoma</em>), but occur in <em>Petromyzon marinus</em> (Sea Lamprey), a jawless vertebrate. The closest homologs to RPE65 in <em>Ciona</em> and <em>Branchiostoma</em> lacked predicted functionally diverged residues found in all authentic RPE65s, but lamprey RPE65 contained all of them. We cloned RPE65 and LRATb cDNAs from lamprey RPE and demonstrated appropriate enzymatic activities. We show that <em>Ciona</em> ß-carotene monooxygenase a (BCMOa) (previously annotated as an RPE65) has carotenoid oxygenase cleavage activity but not RPE65 activity. We verified the presence of RPE65 in lamprey RPE by immunofluorescence microscopy, immunoblot and mass spectrometry. On the basis of these data we conclude that the crucial transition from the typical carotenoid double bond cleavage functionality (BCMO) to the isomerohydrolase functionality (RPE65), coupled with the origin of LRAT, occurred subsequent to divergence of the more primitive chordates (tunicates, etc.) in the last common ancestor of the jawless and jawed vertebrates.</p> </div

MALDI-TOF Lamprey RPE65 peptide mass fingerprinting.

<p>Theoretical monoisotopic masses for Lamprey RPE65 trypsin-generated peptides were determined by MS-Digest.</p

Maximum likelihood phylogenetic tree of the RPE65/BCMO superfamily (the WAG substitution model, the complete deletion option, the uniform rate of substitutions option as implemented in the MEGA5 program).

<p>The numbers for the interior branches refer to the bootstrap values with 1,000 pseudoreplicates. Ciona_s stands for <i>Ciona savignyi</i>.</p

Production of 11-<i>cis</i> retinol by Lamprey RPE65 in HEK293F cells.

<p>A: Normal-phase HPLC of retinol isomers from saponified retinyl esters isolated from HEK293F cells expressing Lamprey RPE65 and bovine LRAT (<i>blue trace</i>). B: Normal-phase HPLC of retinol isomers from saponified retinyl esters isolated from HEK293F cells expressing Lamprey RPE65 with Lamprey LRAT (<i>red trace</i>) or only Lamprey LRAT (<i>green trace</i>).</p