Endogenous electromagnetic fields in plant leaves: a new hypothesis for vascular pattern formation

Electromagnetic (EM) phenomena have long been implicated in biological development, but few detailed, practical mechanisms have been put forth to connect electromagnetism with morphogenetic processes. This work describes a new hypothesis for plant leaf veination, whereby an endogenous electric field forming as a result of a coherent Frohlich process, and corresponding to an EM resonant mode of the developing leaf structure, is capable of instigating leaf vascularisation. In order to test the feasibility of this hypothesis, a three-dimensional, EM finite-element model (FEM) of a leaf primordium was constructed to determine if suitable resonant modes were physically possible for geometric and physical parameters similar to those of developing leaf tissue. Using the FEM model, resonant EM modes with patterns of relevance to developing leaf vein modalities were detected. On account of the existence of shared geometric signatures in a leaf's vascular pattern and the electric field component of EM resonant modes supported by a developing leaf structure, further theoretical and experimental investigations are warranted. Significantly, this hypothesis is not limited to leaf vascular patterning, but may be applicable to a variety of morphogenetic phenomena in a number of living systems.     

Structural evidence for electromagnetic resonance in plant morphogenesis

How a homogeneous collective of cells consistently and precisely establishes long-range tissue patterns remains a question of active research. This work explores the hypothesis of plant organs as resonators for electromagnetic radiation. Long-range structural patterns in the developing ovaries and male flower buds of cucurbit plants (zucchini, acorn, and butternut squash), in addition to mature cucurbit fruits (acorn, butternut, and zucchini squash; watermelon, and cucumber), were investigated. A finite element analysis (FEA) model was used to determine resonant EM modes for models with similar geometric and electrical parameters to those of developing organs. Main features of the developing ovaries (i.e. shape of placental lines, ovum location, definition of distinct tissue regions), male flower buds (i.e. early pollen tube features), and mature fruits (i.e. septa placement, seed location, endocarp and mesocarp) showed distinct correlations with electric and magnetic field components of electromagnetic resonant modes. On account of shared pattern signatures in developing organs and the EM resonant modes supported by a modelled structure with similar geometric and electrical properties to those of cucurbit organs, experimental investigations are warranted. The concept of a developing organ as an EM dielectric resonator may extend to a variety of morphogenetic phenomena in a number of living systems.     

Modeling electromagnetic fields detectability in a HH-like neuronal system: stochastic resonance and window behavior

Noise has already been shown to play a constructive role in neuronal processing and reliability, according to stochastic resonance (SR). Here another issue is addressed, concerning noise role in the detectability of an exogenous signal, here representing an electromagnetic (EM) field. A Hodgkin–Huxley like neuronal model describing a myelinated nerve fiber is proposed and validated, excited with a suprathreshold stimulation. EM field is introduced as an additive voltage input and its detectability in neuronal response is evaluated in terms of the output signal-to-noise ratio. Noise intensities maximizing spiking activity coherence with the exogenous EM signal are clearly shown, indicating a stochastic resonant behavior, strictly connected to the model frequency sensitivity. In this study SR exhibits a window of occurrence in the values of field frequency and intensity, which is a kind of effect long reported in bioelectromagnetic experimental studies. The spatial distribution of the modeled structure also allows to investigate possible effects on action potentials saltatory propagation, which results to be reliable and robust over the presence of an exogenous EM field and biological noise. The proposed approach can be seen as assessing biophysical bases of medical applications funded on electric and magnetic stimulation where the role of noise as a cooperative factor has recently gained growing attention. This work investigates the role of noise as a cooperative factor for the detection of an exogenous electromagnetic field in a compartimental model of a myelinated nerve fiber. The occurrence of stochastic resonance is discussed in relation to neuronal frequency sensitivity.     

Inverted vascular bundles in the leaf of Cladium (Cyperaceae)

Illustrations of seedling development and the adult plant of Cladium jamaicense Crantz are given. The course of vascular bundles in the leaf is described in detail. The structure of seedling and adult leaves are compared. Development of leaf primordia and initiation of vascular bundles are followed. Changes in the anatomy within one leaf and differences between foliage leaves and scales are related to their development. The adaxial vascular bundles that are inversely orientated are initiated within a procambial complex in close association with the largest abaxial bundles. Normally orientated adaxial bundles have an origin independent of other bundles. A hypothesis is presented which accounts for the differentiation of inverted bundles in morphogenetic terms. No developmental evidence was found to support the phylogenetic derivation of the leaf of Cladium by adaxial folding and fusion of laminar halves with their own adaxial surfaces.     

Multispectral Plasmon-Induced Transparency Based on Asymmetric Metallic Nanoslices Array Metasurface

We propose a 3D metasurface structure with unsymmetrical metallic slices array. The tunable plasmon-induced transparency (PIT) effects and different electric field mode distributions could be realized by modulating the structure parameters and angle of incidence. The radiative and dark elements of the asymmetric metallic slices unit cell structure are analyzed. The transmission spectra and the electric fields distributions are studied by the finite element method (FEM). We demonstrate that PIT phenomena based on those metasurface array structures may have applications as tunable sensors and filters in nanophotonics and integrated optics.     

Exploring how extracellular electric field modulates neuron activity through dynamical analysis of a two-compartment neuron model

To investigate how extracellular electric field modulates neuron activity, a reduced two-compartment neuron model in the presence of electric field is introduced in this study. Depending on neuronal geometric and internal coupling parameters, the behaviors of the model have been studied extensively. The neuron model can exist in quiescent state or repetitive spiking state in response to electric field stimulus. Negative electric field mainly acts as inhibitory stimulus to the neuron, positive weak electric field could modulate spiking frequency and spike timing when the neuron is already active, and positive electric fields with sufficient intensity could directly trigger neuronal spiking in the absence of other stimulations. By bifurcation analysis, it is observed that there is saddle-node on invariant circle bifurcation, supercritical Hopf bifurcation and subcritical Hopf bifurcation appearing in the obtained two parameter bifurcation diagrams. The bifurcation structures and electric field thresholds for triggering neuron firing are determined by neuronal geometric and coupling parameters. The model predicts that the neurons with a nonsymmetric morphology between soma and dendrite, are more sensitive to electric field stimulus than those with the spherical structure. These findings suggest that neuronal geometric features play a crucial role in electric field effects on the polarization of neuronal compartments. Moreover, by determining the electric field threshold of our biophysical model, we could accurately distinguish between suprathreshold and subthreshold electric fields. Our study highlights the effects of extracellular electric field on neuronal activity from the biophysical modeling point of view. These insights into the dynamical mechanism of electric field may contribute to the investigation and development of electromagnetic therapies, and the model in our study could be further extended to a neuronal network in which the effects of electric fields on network activity may be investigated.     

Electromagnetic Field Propagation in the One-Dimensional Silver Nanoparticle Dimer Chains: Hotspots and Energy Transport

Strong local electromagnetic (EM) fields and efficient EM energy transport in metallic nanostructures are two important issues in their applications in quantum computations/communications. We investigate the propagation characteristics of the hotspots in one-dimensional silver nanoparticle dimer chains, which combine the functions of the gap field enhancement and the waveguide. The near field and the far field induced interplay among the local field enhancement, the radiative interaction, and the dissipation affects significantly the EM field transport efficiency. Moreover, the correlation between local structure and global structure leads to the structure-dependent excitation. With the help of the combined effects of the structure-dependent excitation, the field confinement and the propagation, the efficient EM field excitation, and long-range propagation can be obtained by tuning the structure of our systems. With suitable geometric parameters (dimer orientations, dimer gap sizes) of our system, the electric field intensity at the position 5000 nm away from the starting point (exciting point) is about 50 times of the corresponding field intensity in a silver nanoparticle chain.

     

Error field amplification near the stability boundary of the modes interacting with a conducting wall

The effect is considered of the amplification of an external resonant error field near the stability boundary of the so-called resistive wall modes observed in the DIII-D tokamak. The analysis is performed in a standard cylindrical approximation. The model is based on Maxwell’s equations and Ohm’s law; therefore, the results of the analysis are valid for any large-scale modes interacting with a conducting wall. In contrast to earlier approaches, the model considers the resonant field amplification as a dynamic effect. It is shown that, when the effect is the strongest, the stationary solutions proposed earlier are inapplicable. The problem of plasma response to a probing pulse of the resonant field of a given amplitude and duration is analyzed. The relationships obtained explain the basic features of the observed phenomena in the DIII-D tokamak and allow direct experimental verification.     

Mode Evolution and Transmission Suppression in a Perforated Ultrathin Metallic Film with a Triangular Array of Holes

We theoretically study the evolution of the resonant modes and the transmission suppression (TS) effect in a perforated ultrathin metallic film (PUMF) with a periodic triangular array of holes. It is found that the properties of different resonances change as the hole radius increases, and the non-monotonic shift of resonant frequency can be interpreted qualitatively from the electric field distribution other than the Fano model. In addition, we analyze the strong mode interaction phenomenon in PUMF. When the diameter of holes approaches to four fifths of the lattice constant, the coupling between dipolar resonance and decapolar resonance can lead to an anticrossing and a large Rabi splitting, which is not available in PUMFs with square lattice; the resulting hybrid modes can be ascribed to the quasi-inphase and quasi-antiphase interferences between dipolar resonance and decapolar resonance. By comparing the TS effect of different resonances under different hole radii, we conclude that although dipolar resonance, short-range surface plasmons, and hybrid modes can all contribute to TS effect; the prominent TS effect in our structure should be mainly caused by the collective dipolar resonance of the structure. These findings might be of interest for the future studies in PUMF-based structures and devices.     

Do ectomycorrhizas alter leaf-litter decomposition in monodominant tropical forests of Guyana?

This work tested the hypothesis that ectomycorrhizas (EM) of Dicymbe corymbosa alter leaf-litter decomposition and residual litter quality in tropical forests of Guyana. Mass loss of leaf litter in litter bags was determined on three occasions, in two experiments, during a 12-month period. Paired root-exclusion plots were located randomly within a D. corymbosa forest. Both D. corymbosa and mixed-species leaf litters were reciprocally transplanted into their respective forest types. Elemental analysis was performed on the residual D. corymbosa leaf litter after 1 yr. Leaf litter mass loss in the D. corymbosa forest was not influenced by EM, despite high EM colonization. Elemental analysis of D. corymbosa leaf litter residues demonstrated reduced calcium levels in the presence of EM, which were negatively correlated with EM rootlet-colonizing mass. The lack of EM effect on the litter decomposition rate, coupled with high EM colonization, suggests an important but indirect role in mineral nutrient acquisition. Lowered Ca concentration in leaf litter exposed to EM may suggest a high Ca demand by the ectotroph system.     

Mechanisms for removal of developmentally abnormal cells: cell competition and morphogenetic apoptosis

Various cell differentiation signals are tightly linked with apoptotic signals. For example, as a result of somatic mutations, cells within a developing field occasionally receive an altered level of morphogenetic signaling that gives rise to an abnormal cell type. However, these developmentally abnormal cells are frequently removed by activating apoptotic signals. Although such phenomena are crucial for assuring normal development and maintaining a healthy state of various organs, the molecular mechanisms that sense aberrant signals and activate the apoptotic pathway(s) have not fully been investigated. In this review, we discuss recent progress in this area. Cell competition and morphogenetic apoptosis are two kinds of cell death, both of which are mediated by abnormal signaling of Dpp, a member of the TGF-beta superfamily that functions in Drosophila as a morphogen, mitogen and survival factor. Cell competition results in autonomous apoptosis induced by reduced reception of the extracellular survival factor Dpp, while morphogenetic apoptosis is nonautonomous, and is induced by contact of cells receiving different levels of Dpp signaling.     

The Occurrence of Funnel Leaflets and Ring Fasciations in Yellow Lupins

Funnel leaflets in yellow lupins (Lupinus luteus L.) were observedon a mutant, on pea-mosaic infected plants, and on plants treatedwith 2,4-D. In addition typical ring fasciations were producedon plants treated with 2,4-D. The above phenomena have beendiscussed in the light of similar morphogenetic effects, reportedto be induced in other plants by various growth substances.A possible explanation for the ring-shaped structures has beengiven by assuming a change in the influence of the apical meristemon developing leaf primordia and by considering the ‘physiologicalfield’ concept for organ formation respectively.     

Does direction of induced electric field or current provide a test of mechanism involved in nerve regeneration?

We suggest an experimental comparison of two directions for applying the time-varying magnetic fields which have been found to speed spontaneous regeneration of injured peripheral nerves and in attempts to repair spinal cord injuries. Time-varying magnetic fields induce currents in a plane perpendicular to the magnetic field direction. The lower conductivity of the spinal cord's sheath (dura matter) or of the myelin sheath of peripheral nerves would seem to confine the induced electric fields and currents to the spinal cord or nerve itself. The proposed comparison could allow choosing between two possible modes of action of the fields: (1) Magnetically-induced electric fields or currents may be encouraging ion flow or otherwise helping enzyme, channel or other interactions at the cell membrane, as is thought to be the case in field stimulation of healing in bone. This mechanism should be independent of field direction. (2) Work in developing organisms and with fields applied to nerve cells in vitro has shown that neurite growth is guided parallel to both endogenous and external electric fields. This mechanism would be effective when induced electric fields are parallel, but not when they are perpendicular to the nerve. Any experimental test should seek to produce as close as possible to the same induced current intensity with both field directions. Possible confounding factors, as well as breakdowns in the assumptions of the simple model presented here, would have to be considered. This proposal was motivated by a recent report in which the authors listed a changed field direction as one of several possible reasons for an unsuccessful experiment.     

Dielectro-deformations of erythrocyte: analysis of the ellipsoidal shear model

Using the theoretical analysis within the framework of the proposed ellipsoidal shear electromechanical model of erythrocyte, the main mechanisms and relationships have been established and studied for the deformations of erythrocytes caused by a spatially homogeneous high-frequency electric field. The main types of the stress-strain curves characteristic of stationary and dynamic deformations caused by the rectangular-pulse and harmonic modulations of the field amplitude have been calculated. The relationship has been established between the parameters of essentially nonlinear stress-strain curves and mechanical, electric, and geometric parameters of erythrocyte. The impossibility of unlimited elongation of erythrocyte by the field, due to the conservation of the cell volume and surface area, has been shown, and the dependence of the maximum possible elongation of the cell on its volume has been calculated. It has been shown that the relaxation time of dynamic deformations of erythrocyte in the presence of an electric field considerably differs from that characteristic of the membrane material and sharply decreases with the increase of the initial elongation of the cell.     

Multi-Band Ultra-Sharp Transmission Response in All-Dielectric Resonant Structures Containing Kerr Nonlinear Media

All-dielectric resonant structure (ADRS) consisting of high-index nonlinear dielectrics has been theoretically and numerically demonstrated with multi-band ultra-sharp transmission response in this work. Bandwidth down to sub-nanometer and spectral Q-factor up to 920 are achieved in this ADRS-based metamaterial-like platform. Strong resonant electric field distributions by the high-index dielectric resonators and efficient coupling between the layered dielectric particles and the cavity mainly contribute to the multiple narrowband light transmission filtering. By using a Kerr nonlinear medium as the resonant dielectric, the positions of the transmission dips in the spectrum can be actively tuned by the incident light intensity. Due to the ultra-narrow spectral feature and the strong electric field distribution by the resonators, an efficient all-optical switching behavior with high spectral difference intensity and contrast ratio is obtained. Further study presents the observed multi-band transmission with high scalability by tuning the structural parameters. These optical features hold the predicted ADRS be potentially applied to constructing dielectric metamaterial-based all-optical switching or active subtractive transmission filtering with low power threshold at sub-diffraction scale.     

OsPNH1 regulates leaf development and maintenance of the shoot apical meristem in rice

The Arabidopsis PINHEAD/ZWILLE (PNH/ZLL) gene is thought to play an important role in the formation of the shoot apical meristem (SAM) and in leaf adaxial cell specification. To investigate the molecular mechanisms of rice development, we have isolated a rice homologue of PNH/ZLL, called OsPNH1. Around the SAM, OsPNH1 was strongly expressed in developing leaf primordia, specifically in the presumptive vascular domains, developing vascular tissues, a few cell-layers of the adaxial region, and future bundle sheath extension cells. In the SAM, only weak expression was observed in the central region, whereas strong expression was detected in the mid-vein region of leaf founder cells in the peripheral SAM domain. We produced transgenic rice plants containing the antisense OsPNH1 strand. The antisense OsPNH1 plants developed malformed leaves with an altered vascular arrangement and abnormal internal structure. These plants also formed an aberrant SAM with reduced KNOX gene expression. We examined the subcellular localization of the OsPNH1-GFP fusion protein and found that it was localized in the cytoplasm. On the basis of these observations, we propose that OsPNH1 functions not only in SAM maintenance as previously thought, but also in leaf formation through vascular development.     

Framework of Collagen Type I – Vasoactive Vessels Structuring Invariant Geometric Attractor in Cancer Tissues: Insight into Biological Magnetic Field

In a previous research, we have described and documented self-assembly of geometric triangular chiral hexagon crystal-like complex organizations (GTCHC) in human pathological tissues. This article documents and gathers insights into the magnetic field in cancer tissues and also how it generates an invariant functional geometric attractor constituted for collider partners in their entangled environment. The need to identify this hierarquic attractor was born out of the concern to understand how the vascular net of these complexes are organized, and to determine if the spiral vascular subpatterns observed adjacent to GTCHC complexes and their assembly are interrelational. The study focuses on cancer tissues and all the macroscopic and microscopic material in which GTCHC complexes are identified, which have been overlooked so far, and are rigorously revised. This revision follows the same parameters that were established in the initial phase of the investigation, but with a new item: the visualization and documentation of external dorsal serous vascular bed areas in spatial correlation with the localization of GTCHC complexes inside the tumors. Following the standard of the electro-optical collision model, we were able to reproduce and replicate collider patterns, that is, pairs of left and right hand spin-spiraled subpatterns, associated with the orientation of the spinning process that can be an expansion or contraction disposition of light particles. Agreement between this model and tumor data is surprisingly close; electromagnetic spiral patterns generated were identical at the spiral vascular arrangement in connection with GTCHC complexes in malignant tumors. These findings suggest that the framework of collagen type 1 – vasoactive vessels that structure geometric attractors in cancer tissues with invariant morphology sets generate collider partners in their magnetic domain with opposite biological behavior. If these principles are incorporated into nanomaterial, biomedical devices, and engineered tissues, new therapeutic strategies could be developed for cancer treatment.     

Measurement of small mechanical vibrations of brain tissue exposed to extremely-low-frequency electric fields

Electromagnetic fields can interact with biological tissue both electrically and mechanically. This study investigated the mechanical interaction between brain tissue and an extremely-low-frequency (ELF) electric field by measuring the resultant vibrational amplitude. The exposure cell is a section of X-band waveguide that was modified by the addition of a center conductor to form a small TEM cell within the waveguide structure. The ELF signal is applied to the center conductor of the TEM cell. The applied ELF electric field generates an electrostrictive force on the surface of the brain tissue. This force causes the tissue to vibrate at a frequency equal to twice the frequency of the applied sinusoidal signal. An X-band signal is fed through the waveguide, scattered by the vibrating sample, and detected by a phase-sensitive receiver. Using a time-averaging spectrum analyzer, a vibration sensitivity of approximately 0.2 nmp-p can be achieved. The amplitude of the brain tissue vibrational response is constant for vibrational frequencies below 50 Hz; between 50 and 200 Hz resonant phenomena were observed; and above 200 Hz the amplitude fall-off is rapid.     

Flowering in bougainvillea: a function of assimilate supply and nutrient diversion

Reproductive development, whether expressed as first node to flower or numbers of inflorescences developing, is promoted in direct relationship to leaf area and in inverse relationship to the numbers of axillary branches developing. Per cent soluble solids in the reproductive shoots vary with reproductive development. Cytokinin treatments promote inflorescence development and per cent soluble solids, further supporting a nutritional hypothesis in the control of flowering in Bougainvillea “San Diego Red.” Gibberellin treatments inhibit reproductive development completely without significant lowering of per cent soluble solids, which is counter to expectations for a nutritional hypothesis. A closer examination of the reproductive axes, the tissues in which morphogenetic change occurs, must be made for the gibberellin-treated tissues.