Binocular Mirror-Symmetric Microsaccadic Sampling of Hyperacute 3D-Vision

Neural mechanisms behind stereopsis, which requires simultaneous disparity inputs from two eyes, have remained mysterious. Here we show how ultrafast mirror-symmetric photomechanical contractions in the frontal forward-facing left and right eye photoreceptors give Drosophila super-resolution 3D-vision. By interlinking multiscale in vivo assays with multiscale simulations, we reveal how these photoreceptor microsaccades - by verging, diverging and narrowing the eyes' overlapping receptive fields - channel depth information, as phasic binocular image motion disparity signals in time. We further show how peripherally, outside stereopsis, microsaccadic sampling tracks a forward flying fly's optic flow field to better resolve the world in motion. These results change our understanding of how insect compound eyes work and suggest a general dynamic stereo-information sampling strategy for animals, robots and sensors.

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Programmable in vitro Co-Encapsidation of Guest Proteins Inside Protein Nanocages

10.26434/chemrxiv.5844393 ◽

2018 ◽

Author(s):

Noor H. Dashti ◽

Rufika S. Abidin ◽

Frank Sainsbury

Keyword(s):

Self Assembly ◽

Mammalian Cells ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Super Resolution ◽

Cell Engineering ◽

Particle Analysis ◽

Protein Cages

Bioinspired self-sorting and self-assembling systems using engineered versions of natural protein cages have been developed for biocatalysis and therapeutic delivery. The packaging and intracellular delivery of guest proteins is of particular interest for both in vitro and in vivo cell engineering. However, there is a lack of platforms in bionanotechnology that combine programmable guest protein encapsidation with efficient intracellular uptake. We report a minimal peptide anchor for in vivo self-sorting of cargo-linked capsomeres of the Murine polyomavirus (MPyV) major coat protein that enables controlled encapsidation of guest proteins by in vitro self-assembly. Using Förster resonance energy transfer (FRET) we demonstrate the flexibility in this system to support co-encapsidation of multiple proteins. Complementing these ensemble measurements with single particle analysis by super-resolution microscopy shows that the stochastic nature of co-encapsidation is an overriding principle. This has implications for the design and deployment of both native and engineered self-sorting encapsulation systems and for the assembly of infectious virions. Taking advantage of the encoded affinity for sialic acids ubiquitously displayed on the surface of mammalian cells, we demonstrate the ability of self-assembled MPyV virus-like particles to mediate efficient delivery of guest proteins to the cytosol of primary human cells. This platform for programmable co-encapsidation and efficient cytosolic delivery of complementary biomolecules therefore has enormous potential in cell engineering.

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Monocular Depth Estimation with Joint Attention Feature Distillation and Wavelet-Based Loss Function

Sensors ◽

10.3390/s21010054 ◽

2020 ◽

Vol 21 (1) ◽

pp. 54

Author(s):

Peng Liu ◽

Zonghua Zhang ◽

Zhaozong Meng ◽

Nan Gao

Keyword(s):

Joint Attention ◽

Loss Function ◽

Depth Estimation ◽

Depth Information ◽

3D Vision ◽

Network Training ◽

Crucial Component ◽

Benchmark Datasets ◽

Ill Posed ◽

Monocular Depth

Depth estimation is a crucial component in many 3D vision applications. Monocular depth estimation is gaining increasing interest due to flexible use and extremely low system requirements, but inherently ill-posed and ambiguous characteristics still cause unsatisfactory estimation results. This paper proposes a new deep convolutional neural network for monocular depth estimation. The network applies joint attention feature distillation and wavelet-based loss function to recover the depth information of a scene. Two improvements were achieved, compared with previous methods. First, we combined feature distillation and joint attention mechanisms to boost feature modulation discrimination. The network extracts hierarchical features using a progressive feature distillation and refinement strategy and aggregates features using a joint attention operation. Second, we adopted a wavelet-based loss function for network training, which improves loss function effectiveness by obtaining more structural details. The experimental results on challenging indoor and outdoor benchmark datasets verified the proposed method’s superiority compared with current state-of-the-art methods.

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Gran1: A Granulysin-Derived Peptide with Potent Activity against Intracellular Mycobacterium tuberculosis

International Journal of Molecular Sciences ◽

10.3390/ijms22168392 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8392

Author(s):

Reiner Noschka ◽

Fanny Wondany ◽

Gönül Kizilsavas ◽

Tanja Weil ◽

Gilbert Weidinger ◽

...

Keyword(s):

Antimicrobial Activity ◽

Mycobacterium Tuberculosis ◽

Developmental Toxicity ◽

Super Resolution ◽

In Vivo Models ◽

Large Size ◽

Acid Fragment ◽

Powerful Approach ◽

Target Effects

Granulysin is an antimicrobial peptide (AMP) expressed by human T-lymphocytes and natural killer cells. Despite a remarkably broad antimicrobial spectrum, its implementation into clinical practice has been hampered by its large size and off-target effects. To circumvent these limitations, we synthesized a 29 amino acid fragment within the putative cytolytic site of Granulysin (termed “Gran1”). We evaluated the antimicrobial activity of Gran1 against the major human pathogen Mycobacterium tuberculosis (Mtb) and a panel of clinically relevant non-tuberculous mycobacteria which are notoriously difficult to treat. Gran1 efficiently inhibited the mycobacterial proliferation in the low micro molar range. Super-resolution fluorescence microscopy and scanning electron microscopy indicated that Gran1 interacts with the surface of Mtb, causing lethal distortions of the cell wall. Importantly, Gran1 showed no off-target effects (cytokine release, chemotaxis, cell death) in primary human cells or zebrafish embryos (cytotoxicity, developmental toxicity, neurotoxicity, cardiotoxicity). Gran1 was selectively internalized by macrophages, the major host cell of Mtb, and restricted the proliferation of the pathogen. Our results demonstrate that the hypothesis-driven design of AMPs is a powerful approach for the identification of small bioactive compounds with specific antimicrobial activity. Gran1 is a promising component for the design of AMP-containing nanoparticles with selective activity and favorable pharmacokinetics to be pushed forward into experimental in vivo models of infectious diseases, most notably tuberculosis.

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Inducibility, but not stability, of atrial fibrillation is increased by NOX2 overexpression in mice

Cardiovascular Research ◽

10.1093/cvr/cvab019 ◽

2021 ◽

Author(s):

Alexandra S Mighiu ◽

Alice Recalde ◽

Klemen Ziberna ◽

Ricardo Carnicer ◽

Jakub Tomek ◽

...

Keyword(s):

Atrial Fibrillation ◽

Superoxide Production ◽

Right Atrial ◽

Burst Stimulation ◽

Lv Mass ◽

Surface Ecg ◽

Tissue Homogenates ◽

Genotype Difference ◽

Left And Right

Abstract Aims Gp91-containing NADPH oxidases (NOX2) are a significant source of myocardial superoxide production. An increase in NOX2 activity accompanies atrial fibrillation (AF) induction and electrical remodelling in animal models and predicts incident AF in humans; however, a direct causal role for NOX2 in AF has not been demonstrated. Accordingly, we investigated whether myocardial NOX2 overexpression in mice (NOX2-Tg) is sufficient to generate a favourable substrate for AF and further assessed the effects of atorvastatin, an inhibitor of NOX2, on atrial superoxide production and AF susceptibility. Methods and results NOX2-Tg mice showed a 2- to 2.5-fold higher atrial protein content of NOX2 compared with wild-type (WT) controls, which was associated with a significant (twofold) increase in NADPH-stimulated superoxide production (2-hydroxyethidium by HPLC) in left and right atrial tissue homogenates (P = 0.004 and P = 0.019, respectively). AF susceptibility assessed in vivo by transoesophageal atrial burst stimulation was modestly increased in NOX2-Tg compared with WT (probability of AF induction: 88% vs. 69%, respectively; P = 0.037), in the absence of significant alterations in AF duration, surface ECG parameters, and LV mass or function. Mechanistic studies did not support a role for NOX2 in promoting electrical or structural remodelling, as high-resolution optical mapping of atrial tissues showed no differences in action potential duration and conduction velocity between genotypes. In addition, we did not observe any genotype difference in markers of fibrosis and inflammation, including atrial collagen content and Col1a1, Il-1β, Il-6, and Mcp-1 mRNA. Similarly, NOX2 overexpression did not have consistent effects on RyR2 Ca2+ leak nor did it affect PKA or CaMKII-mediated RyR2 phosphorylation. Finally, treatment with atorvastatin significantly inhibited atrial superoxide production in NOX2-Tg but had no effect on AF induction in either genotype. Conclusion Together, these data indicate that while atrial NOX2 overexpression may contribute to atrial arrhythmogenesis, NOX2-derived superoxide production does not affect the electrical and structural properties of the atrial myocardium.

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In vivo optical endomicroscopy: two decades of translational research towards next generation diagnosis of eosinophilic esophagitis

Translational Medicine Communications ◽

10.1186/s41231-020-00080-z ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Andreas Wartak ◽

John G. Garber ◽

Qian Yuan ◽

Wayne G. Shreffler ◽

Paul E. Hesterberg ◽

...

Keyword(s):

Eosinophilic Esophagitis ◽

Massachusetts General Hospital ◽

Standard Of Care ◽

Depth Information ◽

Current Standard ◽

Promising Alternative ◽

White Light Endoscopy ◽

Related Risk ◽

Histopathologic Analysis

AbstractHistopathologic analysis of biopsy specimens obtained via white light endoscopy (WLE) is the gold standard for the diagnosis of several mucosal diseases in the upper gastrointestinal (GI) tract. However, this standard of care entails a series of critical shortcomings such as missing depth information, high costs, time inefficiency, low-resolution imaging in vivo, high sampling variability, missing intrinsic tissue-specific contrast, and anesthesia related risk. In the quest for a diagnostic technology to replace the current standard of care, in vivo optical endomicroscopy has emerged as a promising alternative. This paper tells the story of a cluster of optical microscopy-based modalities invented, further developed, or first-validated in the laboratory of Dr. Guillermo J. Tearney (Tearney Lab) at the Wellman Center for Photomedicine of Massachusetts General Hospital over the past two decades, that combined lead to a novel method for diagnosis of eosinophilic esophagitis (EoE). Rather than being a comprehensive literature review, this paper aims to describe the translational journey towards a disease specific diagnostic and research tool for this increasingly recognized yet poorly understood immune-mediated disorder of the esophagus.

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Bias between the Left and Right Inverted Repeats during IS911 Targeted Insertion

Journal of Bacteriology ◽

10.1128/jb.00452-08 ◽

2008 ◽

Vol 190 (18) ◽

pp. 6111-6118 ◽

Cited By ~ 5

Author(s):

P. Rousseau ◽

C. Loot ◽

C. Turlan ◽

S. Nolivos ◽

M. Chandler

Keyword(s):

Insertion Sequence ◽

Regulatory Protein ◽

Open Reading Frames ◽

Inverted Repeats ◽

Functional Differences ◽

Left And Right ◽

Ordered Assembly ◽

Overlapping Open Reading Frames ◽

Reading Frames

ABSTRACT IS911 is a bacterial insertion sequence composed of two consecutive overlapping open reading frames (ORFs [orfA and orfB]) encoding the transposase (OrfAB) as well as a regulatory protein (OrfA). These ORFs are bordered by terminal left and right inverted repeats (IRL and IRR, respectively) with several differences in nucleotide sequence. IS911 transposition is asymmetric: each end is cleaved on one strand to generate a free 3′-OH, which is then used as the nucleophile in attacking the opposite insertion sequence (IS) end to generate a free IS circle. This will be inserted into a new target site. We show here that the ends exhibit functional differences which, in vivo, may favor the use of one compared to the other during transposition. Electromobility shift assays showed that a truncated form of the transposase [OrfAB(1-149)] exhibits higher affinity for IRR than for IRL. While there was no detectable difference in IR activities during the early steps of transposition, IRR was more efficient during the final insertion steps. We show here that the differential activities between the two IRs correlate with the different affinities of OrfAB(1-149) for the IRs during assembly of the nucleoprotein complexes leading to transposition. We conclude that the two inverted repeats are not equivalent during IS911 transposition and that this asymmetry may intervene to determine the ordered assembly of the different protein-DNA complexes involved in the reaction.

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A Lightweight Dense Connected Approach with Attention on Single Image Super-Resolution

Electronics ◽

10.3390/electronics10111234 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1234

Author(s):

Lei Zha ◽

Yu Yang ◽

Zicheng Lai ◽

Ziwei Zhang ◽

Juan Wen

Keyword(s):

Receptive Fields ◽

Super Resolution ◽

Feature Representation ◽

Single Image ◽

Deep Model ◽

Benchmark Datasets ◽

Rich Information ◽

Image Super Resolution ◽

Model Training ◽

Single Image Super Resolution

In recent years, neural networks for single image super-resolution (SISR) have applied more profound and deeper network structures to extract extra image details, which brings difficulties in model training. To deal with deep model training problems, researchers utilize dense skip connections to promote the model’s feature representation ability by reusing deep features of different receptive fields. Benefiting from the dense connection block, SRDensenet has achieved excellent performance in SISR. Despite the fact that the dense connected structure can provide rich information, it will also introduce redundant and useless information. To tackle this problem, in this paper, we propose a Lightweight Dense Connected Approach with Attention for Single Image Super-Resolution (LDCASR), which employs the attention mechanism to extract useful information in channel dimension. Particularly, we propose the recursive dense group (RDG), consisting of Dense Attention Blocks (DABs), which can obtain more significant representations by extracting deep features with the aid of both dense connections and the attention module, making our whole network attach importance to learning more advanced feature information. Additionally, we introduce the group convolution in DABs, which can reduce the number of parameters to 0.6 M. Extensive experiments on benchmark datasets demonstrate the superiority of our proposed method over five chosen SISR methods.

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Abstract 13383: The Vascular Endothelial Barrier: A Novel Therapeutic Target for Preventing Atrial Fibrillation

Circulation ◽

10.1161/circ.142.suppl_3.13383 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Louisa Mezache ◽

Heather Struckman ◽

Anna Phillips ◽

Stephen Baine ◽

Amara Greer-short ◽

...

Keyword(s):

Atrial Fibrillation ◽

Ex Vivo ◽

Vascular Dysfunction ◽

Super Resolution ◽

Vascular Endothelial ◽

Vascular Leak ◽

Barrier Breakdown ◽

Endothelial Growth Factor ◽

Intercalated Disk

Atrial fibrillation (AF), the most common arrhythmia, is associated with inflammation and vascular dysfunction. AF patients have elevated levels of vascular endothelial growth factor (VEGF; 90-580 pg/ml), which promotes vascular leak and edema. We have previously identified edema-induced disruption of sodium channel (Na V 1.5) -rich intercalated disk (ID) nanodomains as a novel arrhythmia mechanism. We hypothesized that (i) elevated VEGF levels promote AF by disrupting ID nanodomains, and slowing atrial conduction, and (ii) protection of the vascular barrier can prevent these arrhythmias. Clinically-relevant VEGF levels (500 pg/ml, 60 minutes) increased FITC-dextran extravasation (99.3% vs. 24.3% in vehicle controls) in WT mouse hearts, consistent with increased vascular leak. Electron microscopy revealed ID nanodomain swelling, near both gap junctions (perinexi; 64±9nm vs 17±1nm) and mechanical junctions (63±4nm vs 27±2nm) in VEGF-treated hearts relative to controls. Super-resolution STORM microscopy revealed Na V 1.5 enrichment at perinexi (9±2 fold) and N-cadherin-rich sites (7±1 fold) relative to non-junctional ID sites in control hearts. VEGF reduced Na V 1.5 enrichment at both sites (6±1 and 4±1 fold, respectively), consistent with Na V 1.5 translocation from ID nanodomains. Atrial conduction, assessed by optical mapping, was slowed by VEGF (10±0.4 cm/s vs 21.3±1.3 cm/s at baseline). VEGF increased atrial arrhythmia burden both ex vivo (80% vs 0% in vehicle controls) and in vivo (70% vs 20% in vehicle controls). Next, we tested two strategies shown to prevent vascular barrier breakdown. Blocking connexin43 hemichannels (αCT11 peptide) decreased both incidence (40%) and duration (1.45±3.42s) of VEGF-induced arrhythmias. Likewise, blocking pannexin1 channels (Panx1-IL2 peptide) shortened VEGF-induced arrhythmias (2.48±0.83s). Mefloquine and spironolactone, which are small molecules that respectively inhibit Cx43 hemichannels and pannexin channels, were also found to effectively prevent VEGF-induced atrial arrhythmias. These results highlight VEGF-induced vascular leak as a novel mechanism for AF, and suggest vascular barrier protection as an anti-arrhythmic strategy.

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Central modulation of the NO/cGMP pathway affects the MPOA-induced intracavernous pressure response

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2001.281.1.r269 ◽

2001 ◽

Vol 281 (1) ◽

pp. R269-R278 ◽

Cited By ~ 29

Author(s):

Yoshikazu Sato ◽

Weixin Zhao ◽

George J. Christ

Keyword(s):

Preoptic Area ◽

Intrathecal Administration ◽

Neural Mechanisms ◽

Cavernous Nerve ◽

Hypothalamic Nuclei ◽

Organ Level ◽

Intrathecal Drug Administration ◽

Critical Aspects

Alterations in the nitric oxide (NO)/cGMP levels in hypothalamic nuclei, including the medial preoptic area (MPOA), regulate critical aspects of sexual behavior and penile reflexes. However, the effects of altered central nervous system (CNS) NO/cGMP levels at the end organ level, that is, on the magnitude/quality of the erection so achieved [intracavernous pressure (ICP) response], has yet to be evaluated. The goal of this report was to evaluate the effects of intrathecal administration of modulators of NO and cGMP levels on ICP responses to stimulation of the MPOA and cavernous nerve in rats in vivo. In all cases, intrathecal administration of compounds that increase and decrease cGMP and NO levels, respectively, was associated with corresponding increases and decreases in the MPOA-stimulated ICP response. Specifically, sodium nitroprusside (SNP), 8-bromo-cGMP, and sildenafil increased the MPOA-stimulated ICP response, whereas N ω-nitro-l-arginine methyl ester reduced it. None of the intrathecal treatments had detectable effects on blood pressure or the cavernous nerve-stimulated ICP response, although intravenous sildenafil increased the latter. These data clearly indicate that intrathecal drug administration affects central and not peripheral neural mechanisms and, moreover, documents that CNS NO/cGMP levels can affect erectile capacity per se (i.e., ICP) in the rat model.

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Cuttlefish use stereopsis to strike at prey

Science Advances ◽

10.1126/sciadv.aay6036 ◽

2020 ◽

Vol 6 (2) ◽

pp. eaay6036 ◽

Cited By ~ 9

Author(s):

R. C. Feord ◽

M. E. Sumner ◽

S. Pusdekar ◽

L. Kalra ◽

P. T. Gonzalez-Bellido ◽

...

Keyword(s):

Information Processing ◽

Visual Information ◽

Convergent Evolution ◽

Visual Fields ◽

Three Dimensional ◽

Visual Information Processing ◽

Depth Information ◽

Cephalopod Species ◽

Left And Right

The camera-type eyes of vertebrates and cephalopods exhibit remarkable convergence, but it is currently unknown whether the mechanisms for visual information processing in these brains, which exhibit wildly disparate architecture, are also shared. To investigate stereopsis in a cephalopod species, we affixed “anaglyph” glasses to cuttlefish and used a three-dimensional perception paradigm. We show that (i) cuttlefish have also evolved stereopsis (i.e., the ability to extract depth information from the disparity between left and right visual fields); (ii) when stereopsis information is intact, the time and distance covered before striking at a target are shorter; (iii) stereopsis in cuttlefish works differently to vertebrates, as cuttlefish can extract stereopsis cues from anticorrelated stimuli. These findings demonstrate that although there is convergent evolution in depth computation, cuttlefish stereopsis is likely afforded by a different algorithm than in humans, and not just a different implementation.

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