Enhanced magnetic modulation of surface plasmon polaritons on hyperbolic metasurfaces.

In this Letter we demonstrate a fundamentally new, to the best of our knowledge, concept to enhance the magnetic modulation of the surface plasmon polaritons (SPPs) by using hybrid magneto-plasmonic structures consisting of hyperbolic plasmonic metasurfaces and magnetic dielectric substrates. Our results show that the magnetic modulation of SPPs in the proposed structures can be an order of magnitude stronger than in the hybrid metal-ferromagnet multilayer structures conventionally used in active magneto-plasmonics. We believe that this effect will allow for the further miniaturization of magneto-plasmonic devices.

Hyperbolic plasmonics with anisotropic gain-loss metasurfaces.

In this Letter, a fundamentally new concept of realization of hyperbolic plasmonic metasurfaces by anisotropic gain-loss competition is proposed, and the possibility of highly directional propagation and amplification of surface plasmon polaritons is predicted. A simple realistic configuration of such a metasurface represents the periodic array of lossy metallic slabs embedded in the gain matrix. Our results may pave the way for numerous applications ranging from integrated and highly directional quantum light emitters to nonlinear-optical frequency converters.

Spider toxin inhibits gating pore currents underlying periodic paralysis.

Gating pore currents through the voltage-sensing domains (VSDs) of the skeletal muscle voltage-gated sodium channel NaV1.4 underlie hypokalemic periodic paralysis (HypoPP) type 2. Gating modifier toxins target ion channels by modifying the function of the VSDs. We tested the hypothesis that these toxins could function as blockers of the pathogenic gating pore currents. We report that a crab spider toxin Hm-3 from Heriaeus melloteei can inhibit gating pore currents due to mutations affecting the second arginine residue in the S4 helix of VSD-I that we have found in patients with HypoPP and describe here. NMR studies show that Hm-3 partitions into micelles through a hydrophobic cluster formed by aromatic residues and reveal complex formation with VSD-I through electrostatic and hydrophobic interactions with the S3b helix and the S3-S4 extracellular loop. Our data identify VSD-I as a specific binding site for neurotoxins on sodium channels. Gating modifier toxins may constitute useful hits for the treatment of HypoPP.

De novo sequencing, assembly and functional annotation of Armillaria borealis genome.

BACKGROUND: Massive forest decline has been observed almost everywhere as a result of negative anthropogenic and climatic effects, which can interact with pests, fungi and other phytopathogens and aggravate their effects. Climatic changes can weaken trees and make fungi, such as Armillaria more destructive. Armillaria borealis (Marxm. & Korhonen) is a fungus from the Physalacriaceae family (Basidiomycota) widely distributed in Eurasia, including Siberia and the Far East. Species from this genus cause the root white rot disease that weakens and often kills woody plants. However, little is known about ecological behavior and genetics of A. borealis. According to field research data, A. borealis is less pathogenic than A. ostoyae, and its aggressive behavior is quite rare. Mainly A. borealis behaves as a secondary pathogen killing trees already weakened by other factors. However, changing environment might cause unpredictable effects in fungus behavior. RESULTS: The de novo genome assembly and annotation were performed for the A. borealis species for the first time and presented in this study. The A. borealis genome assembly contained ~ 68 Mbp and was comparable with ~ 60 and ~ 79.5 Mbp for the A. ostoyae and A. mellea genomes, respectively. The N50 for contigs equaled 50,544 bp. Functional annotation analysis revealed 21,969 protein coding genes and provided data for further comparative analysis. Repetitive sequences were also identified. The main focus for further study and comparative analysis will be on the enzymes and regulatory factors associated with pathogenicity. CONCLUSIONS: Pathogenic fungi such as Armillaria are currently one of the main problems in forest conservation. A comprehensive study of these species and their pathogenicity is of great importance and needs good genomic resources. The assembled genome of A. borealis presented in this study is of sufficiently good quality for further detailed comparative study on the composition of enzymes in other Armillaria species. There is also a fundamental problem with the identification and classification of species of the Armillaria genus, where the study of repetitive sequences in the genomes of basidiomycetes and their comparative analysis will help us identify more accurately taxonomy of these species and reveal their evolutionary relationships.

Siberian larch (Larix sibirica Ledeb.) mitochondrial genome assembled using both short and long nucleotide sequence reads is currently the largest known mitogenome.

BACKGROUND: Plant mitochondrial genomes (mitogenomes) can be structurally complex while their size can vary from ~ 222 Kbp in Brassica napus to 11.3 Mbp in Silene conica. To date, in comparison with the number of plant species, only a few plant mitogenomes have been sequenced and released, particularly for conifers (the Pinaceae family). Conifers cover an ancient group of land plants that includes about 600 species, and which are of great ecological and economical value. Among them, Siberian larch (Larix sibirica Ledeb.) represents one of the keystone species in Siberian boreal forests. Yet, despite its importance for evolutionary and population studies, the mitogenome of Siberian larch has not yet been assembled and studied. RESULTS: Two sources of DNA sequences were used to search for mitochondrial DNA (mtDNA) sequences: mtDNA enriched samples and nucleotide reads generated in the de novo whole genome sequencing project, respectively. The assembly of the Siberian larch mitogenome contained nine contigs, with the shortest and the largest contigs being 24,767 bp and 4,008,762 bp, respectively. The total size of the genome was estimated at 11.7 Mbp. In total, 40 protein-coding, 34 tRNA, and 3 rRNA genes and numerous repetitive elements (REs) were annotated in this mitogenome. In total, 864 C-to-U RNA editing sites were found for 38 out of 40 protein-coding genes. The immense size of this genome, currently the largest reported, can be partly explained by variable numbers of mobile genetic elements, and introns, but unlikely by plasmid-related sequences. We found few plasmid-like insertions representing only 0.11% of the entire Siberian larch mitogenome. CONCLUSIONS: Our study showed that the size of the Siberian larch mitogenome is much larger than in other so far studied Gymnosperms, and in the same range as for the annual flowering plant Silene conica (11.3 Mbp). Similar to other species, the Siberian larch mitogenome contains relatively few genes, and despite its huge size, the repeated and low complexity regions cover only 14.46% of the mitogenome sequence.

Stepwise large genome assembly approach: a case of Siberian larch (Larix sibirica Ledeb).

BACKGROUND: De novo assembling of large genomes, such as in conifers (~ 12-30 Gbp), which also consist of ~ 80% of repetitive DNA, is a very complex and computationally intense endeavor. One of the main problems in assembling such genomes lays in computing limitations of nucleotide sequence assembly programs (DNA assemblers). As a rule, modern assemblers are usually designed to assemble genomes with a length not exceeding the length of the human genome (3.24 Gbp). Most assemblers cannot handle the amount of input sequence data required to provide sufficient coverage needed for a high-quality assembly. RESULTS: An original stepwise method of de novo assembly by parts (sets), which allows to bypass the limitations of modern assemblers associated with a huge amount of data being processed, is presented in this paper. The results of numerical assembling experiments conducted using the model plant Arabidopsis thaliana, Prunus persica (peach) and four most popular assemblers, ABySS, SOAPdenovo, SPAdes, and CLC Assembly Cell, showed the validity and effectiveness of the proposed stepwise assembling method. CONCLUSION: Using the new stepwise de novo assembling method presented in the paper, the genome of Siberian larch, Larix sibirica Ledeb. (12.34 Gbp) was completely assembled de novo by the CLC Assembly Cell assembler. It is the first genome assembly for larch species in addition to only five other conifer genomes sequenced and assembled for Picea abies, Picea glauca, Pinus taeda, Pinus lambertiana, and Pseudotsuga menziesii var. menziesii.

Mobile genetic elements explain size variation in the mitochondrial genomes of four closely-related Armillaria species.

BACKGROUND: Species in the genus Armillaria (fungi, basidiomycota) are well-known as saprophytes and pathogens on plants. Many of them cause white-rot root disease in diverse woody plants worldwide. Mitochondrial genomes (mitogenomes) are widely used in evolutionary and population studies, but despite the importance and wide distribution of Armillaria, the complete mitogenomes have not previously been reported for this genus. Meanwhile, the well-supported phylogeny of Armillaria species provides an excellent framework in which to study variation in mitogenomes and how they have evolved over time. RESULTS: Here we completely sequenced, assembled, and annotated the circular mitogenomes of four species: A. borealis, A. gallica, A. sinapina, and A. solidipes (116,443, 98,896, 103,563, and 122,167 bp, respectively). The variation in mitogenome size can be explained by variable numbers of mobile genetic elements, introns, and plasmid-related sequences. Most Armillaria introns contained open reading frames (ORFs) that are related to homing endonucleases of the LAGLIDADG and GIY-YIG families. Insertions of mobile elements were also evident as fragments of plasmid-related sequences in Armillaria mitogenomes. We also found several truncated gene duplications in all four mitogenomes. CONCLUSIONS: Our study showed that fungal mitogenomes have a high degree of variation in size, gene content, and genomic organization even among closely related species of Armillara. We suggest that mobile genetic elements invading introns and intergenic sequences in the Armillaria mitogenomes have played a significant role in shaping their genome structure. The mitogenome changes we describe here are consistent with widely accepted phylogenetic relationships among the four species.

Plasmon mediated inverse Faraday effect in a graphene-dielectric-metal structure.

This Letter shows the features of inverse Faraday effect (IFE) in a graphene-dielectric-metal (GDM) structure. The constants of propagation and attenuation of the surface plasmon-polariton modes are calculated. The effective magnetic field induced by surface plasmon modes in the dielectric due to the IFE is estimated to reach above 1 tesla. The possibility to control the distribution of the magnetic field by chemical potential of graphene is shown. The concept of strain-driven control of the IFE in the structure has been proposed and investigated.

De novo assembling and primary analysis of genome and transcriptome of gray whale Eschrichtius robustus.

BACKGROUND: Gray whale, Eschrichtius robustus (E. robustus), is a single member of the family Eschrichtiidae, which is considered to be the most primitive in the class Cetacea. Gray whale is often described as a "living fossil". It is adapted to extreme marine conditions and has a high life expectancy (77 years). The assembly of a gray whale genome and transcriptome will allow to carry out further studies of whale evolution, longevity, and resistance to extreme environment. RESULTS: In this work, we report the first de novo assembly and primary analysis of the E. robustus genome and transcriptome based on kidney and liver samples. The presented draft genome assembly is complete by 55% in terms of a total genome length, but only by 24% in terms of the BUSCO complete gene groups, although 10,895 genes were identified. Transcriptome annotation and comparison with other whale species revealed robust expression of DNA repair and hypoxia-response genes, which is expected for whales. CONCLUSIONS: This preliminary study of the gray whale genome and transcriptome provides new data to better understand the whale evolution and the mechanisms of their adaptation to the hypoxic conditions.

Giant Faraday Rotation of High-Order Plasmonic Modes in Graphene-Covered Nanowires.

Plasmonic Faraday rotation in nanowires manifests itself in the rotation of the spatial intensity distribution of high-order surface plasmon polariton (SPP) modes around the nanowire axis. Here we predict theoretically the giant Faraday rotation for SPPs propagating on graphene-coated magneto-optically active nanowires. Upon the reversal of the external magnetic field pointing along the nanowire axis some high-order plasmonic modes may be rotated by up to ∼100° on the length scale of about 500 nm at mid-infrared frequencies. Tuning the carrier concentration in graphene by chemical doping or gate voltage allows for controlling SPP-properties and notably the rotation angle of high-order azimuthal modes. Our results open the door to novel plasmonic applications ranging from nanowire-based Faraday isolators to the magnetic control in quantum-optical applications.

Plasmonically induced magnetic field in graphene-coated nanowires.

In this Letter, we investigate a magnetic field induced by guiding plasmonic modes in graphene-coated nanowire via an inverse Faraday effect. Magnetic field distribution for different plasmonic modes has been calculated. It has been shown that a magnetic field has a vortex-like distribution for some plasmonic modes. The possibility of producing magnetic field distribution that rotates along the nanowire axis and periodically depends on azimuthal angle has been demonstrated.

Magnetic field control of plasmon polaritons in graphene-covered gyrotropic planar waveguide.

In this Letter, we report about magnetic field switching of plasmon polaritons propagating into a planar gyrotropic waveguide covered by two graphene layers at a deeply subwavelength scale. It is shown that applying an external magnetic field may lead to energy redistribution between two waveguide surfaces. The effect value resonantly depends on the relation between waveguide size and exciting light wavelength. A change in chemical potential of graphene layers may be used for tuning the phase shift between plasmon polaritons at near-resonant wavelengths. Evident effect may be observed at low magnetic fields (less than one tesla) for wavelengths about microns on a scale of tens of nanometers. Such an effect may be used for plasmonics, photonics. and optoelectronics devices, as well as sensing applications.

Influence of graphene coating on speckle-pattern rotation of light in gyrotropic optical fiber.

In the present work, change in speckle-pattern of linearly polarized light passed through graphene-covered optical fiber placed in external magnetic field is investigated. The possibility of magnetic speckle-pattern rotation suppression and inverse speckle-pattern rotation effect is shown. This effect can be controlled by a chemical potential of graphene layer, which can be changed easily by a gate voltage, for example. For quartz optical fiber at wavelength 0.633 µm, core diameter 9 µm, and fiber length 5 cm, an inverse rotation value of 17° is reached at chemical potential of graphene layer about 1 eV and magnetic field strength 30 kOe. Results of the work may be useful for different magneto-optics, opto-electronics, and photonics applications.

Annotation of Siberian Larch (Larix sibirica Ledeb.) Nuclear Genome-One of the Most Cold-Resistant Tree Species in the Only Deciduous GENUS in Pinaceae.

The recent release of the nuclear, chloroplast and mitochondrial genome assemblies of Siberian larch (Larix sibirica Ledeb.), one of the most cold-resistant tree species in the only deciduous genus of Pinaceae, with seasonal senescence and a rot-resistant valuable timber widely used in construction, greatly contributed to the development of genomic resources for the larch genus. Here, we present an extensive repeatome analysis and the first annotation of the draft nuclear Siberian larch genome assembly. About 66% of the larch genome consists of highly repetitive elements (REs), with the likely wave of retrotransposons insertions into the larch genome estimated to occur 4-5 MYA. In total, 39,370 gene models were predicted, with 87% of them having homology to the Arabidopsis-annotated proteins and 78% having at least one GO term assignment. The current state of the genome annotations allows for the exploration of the gymnosperm and angiosperm species for relative gene abundance in different functional categories. Comparative analysis of functional gene categories across different angiosperm and gymnosperm species finds that the Siberian larch genome has an overabundance of genes associated with programmed cell death (PCD), autophagy, stress hormone biosynthesis and regulatory pathways; genes that may play important roles in seasonal senescence and stress response to extreme cold in larch. Despite being incomplete, the draft assemblies and annotations of the conifer genomes are at a point of development where they now represent a valuable source for further genomic, genetic and population studies.

Application of machine learning and laser optical-acoustic spectroscopy to study the profile of exhaled air volatile markers of acute myocardial infarction.

Conventional acute myocardial infarction (AMI) diagnosis is quite accurate and has proved its effectiveness. However, despite this, discovering more operative methods of this disease detection is underway. From this point of view, the application of exhaled air analysis for a similar diagnosis is valuable. The aim of the paper is to research effective machine learning algorithms for the predictive model for AMI diagnosis constructing, using exhaled air spectral data. The target group included 30 patients with primary myocardial infarction. The control group included 42 healthy volunteers. The 'LaserBreeze' laser gas analyzer (Special Technologies Ltd, Russia), based on the dual-channel resonant photoacoustic detector cell and optical parametric oscillator as the laser source, had been used. The pattern recognition approach was applied in the same manner for the set of extracted concentrations of AMI volatile markers and the set of absorption coefficients in a most informative spectral range 2.900 ± 0.125µm. The created predictive model based on the set of absorption coefficients provided 0.86 of the mean values of both the sensitivity and specificity when linear support vector machine (SVM) combined with principal component analysis was used. The created predictive model based on using six volatile AMI markers (C5H12, N2O, NO2, C2H4, CO, CO2) provided 0.82 and 0.93 of the mean values of the sensitivity and specificity, respectively, when linear SVM was used.

Comparative Genomics Analysis of Repetitive Elements in Ten Gymnosperm Species: "Dark Repeatome" and Its Abundance in Conifer and Gnetum Species.

Repetitive elements (RE) and transposons (TE) can comprise up to 80% of some plant genomes and may be essential for regulating their evolution and adaptation. The "repeatome" information is often unavailable in assembled genomes because genomic areas of repeats are challenging to assemble and are often missing from final assembly. However, raw genomic sequencing data contain rich information about RE/TEs. Here, raw genomic NGS reads of 10 gymnosperm species were studied for the content and abundance patterns of their "repeatome". We utilized a combination of alignment on databases of repetitive elements and de novo assembly of highly repetitive sequences from genomic sequencing reads to characterize and calculate the abundance of known and putative repetitive elements in the genomes of 10 conifer plants: Pinus taeda, Pinus sylvestris, Pinus sibirica, Picea glauca, Picea abies, Abies sibirica, Larix sibirica, Juniperus communis, Taxus baccata, and Gnetum gnemon. We found that genome abundances of known and newly discovered putative repeats are specific to phylogenetically close groups of species and match biological taxa. The grouping of species based on abundances of known repeats closely matches the grouping based on abundances of newly discovered putative repeats (kChains) and matches the known taxonomic relations.

Analogue closed-loop optogenetic modulation of hippocampal pyramidal cells dissociates gamma frequency and amplitude.

Gamma-band oscillations are implicated in modulation of attention, integration of sensory information and flexible communication among anatomically connected brain areas. How networks become entrained is incompletely understood. Specifically, it is unclear how the spectral and temporal characteristics of network oscillations can be altered on rapid timescales needed for efficient communication. We use closed-loop optogenetic modulation of principal cell excitability in mouse hippocampal slices to interrogate the dynamical properties of hippocampal oscillations. Gamma frequency and amplitude can be modulated bi-directionally, and dissociated, by phase-advancing or delaying optogenetic feedback to pyramidal cells. Closed-loop modulation alters the synchrony rather than average frequency of action potentials, in principle avoiding disruption of population rate-coding of information. Modulation of phasic excitatory currents in principal neurons is sufficient to manipulate oscillations, suggesting that feed-forward excitation of pyramidal cells has an important role in determining oscillatory dynamics and the ability of networks to couple with one another.

Exhaled air analysis using wideband wave number tuning range infrared laser photoacoustic spectroscopy.

The infrared laser photoacoustic spectroscopy (LPAS) and the pattern-recognition-based approach for noninvasive express diagnostics of pulmonary diseases on the basis of absorption spectra analysis of the patient's exhaled air are presented. The study involved lung cancer patients ( N = 9 ), patients with chronic obstructive pulmonary disease ( N = 12 ), and a control group of healthy, nonsmoking volunteers ( N = 11 ). The analysis of the measured absorption spectra was based at first on reduction of the dimension of the feature space using principal component analysis; thereafter, the dichotomous classification was carried out using the support vector machine. The gas chromatography­mass spectrometry method (GC­MS) was used as the reference. The estimated mean value of the sensitivity of exhaled air sample analysis by the LPAS in dichotomous classification was not less than 90% and specificity was not less than 69%; the analogous results of analysis by GC­MS were 68% and 60%, respectively. Also, the approach to differential diagnostics based on the set of SVM classifiers usage is presented.

Transverse-electric plasmonic modes of cylindrical graphene-based waveguide at near-infrared and visible frequencies.

Transverse-electric (TE) surface plasmons (SPs) are very unusual for plasmonics phenomenon. Graphene proposes a unique possibility to observe these plasmons. Due to transverse motion of carriers, TE SPs speed is usually close to bulk light one. In this work we discuss conditions of TE SPs propagation in cylindrical graphene-based waveguides. We found that the negativity of graphene conductivity's imaginary part is not a sufficient condition. The structure supports TE SPs when the core radius of waveguide is larger than the critical value Rcr. Critical radius depends on the light frequency and the difference of permittivities inside and outside the waveguide. Minimum value of Rcr is comparable with the wavelength of volume wave and corresponds to interband carriers transition in graphene. We predict that use of multilayer graphene will lead to decrease of critical radius. TE SPs speed may differ more significantly from bulk light one in case of epsilon-near-zero core and shell of the waveguide. Results may open the door for practical applications of TE SPs in optics, including telecommunications.