Bioelectric potential changes in the style of Lilium longiflorum Thunb. after self- and cross-pollination of the stigma

Two different types of bioelectric potential changes have been registered in the style of Lilium longiflorum cv. Arai 5 after different treatments of the stigma. Self-pollination induces a bioelectric potential change different from the potential change induced by cross-pollination. Removal of the stigma or apllication of killed compatible pollen induced a bioelectrical response similar to the potential change recorded after cross-pollination. No bioelectric potential change was recorded after application of pollen of Petunia hybrida, pollen of Haemanthus katherinae, killed self-pollen, or no treatment at all.The mean generation time of the bioelectric potential change was 338 min after the treatment. The translocation velocity varied between 1.2 and 5.4 cm h^-1. Both responses are similar to the potential changes registered in Mimosa pudica after different types of stimulation and to the potential changes generated by the phytochrome in Avena coleoptiles. The translocation of the signals is discussed in relation to the models on the translocation in Mimosa. The relation between the bioelectric potential changes and the incompatibility reaction in Lilium longiflorum is discussed.     

Nitric oxide-active compounds modulate the intensity of glutamate-evoked responses in the globus pallidus of the rat

AimThe effects of local applied NO-active compounds on glutamate (GLU)-evoked responses were investigated in globus pallidus (GP) neurons.Main methodsExtracellularly recorded single units from anesthetized rats were treated with GLU before and during the microiontophoretic application of S-nitrosoglutathione (SNOG), a NO donor, and Nω-nitro-l-arginine methyl ester (L-NAME), a NOS inhibitor.Key findingsMost GP cells were excited by SNOG whereas administration of L-NAME induced decrease of GP neurons activity. Nearly all neurons responding to SNOG and/or L-NAME showed significant modulation of their excitatory responses to the administration of iontophoretic GLU. In these cells, the changes induced by NO-active drugs in the magnitude of GLU-evoked responses were used as indicators of NO modulation. In fact, when a NO-active drug was co-iontophoresed with GLU, significant changes in GLU-induced responses were observed: generally, increased magnitudes of GLU-evoked responses were observed during SNOG ejection, whereas the administration of L-NAME decreased responses to GLU.SignificanceThe results suggest that the NO-active drugs modulate the response of GP neurons to glutamatergic transmission. Nitrergic modulation of glutamatergic transmission could play an important role in the control of GP bioelectric activity, considered a fundamental key in the BG function.     

Regulatory T cell adjustment of quorum growth thresholds and the control of local immune responses

The consequences of regulatory T cell (Treg) inhibition of interleukine 2 secretion is examined by mathematical modelling. We demonstrate that cytokine dependent growth exhibits a quorum T cell population threshold that determines if immune responses develop on activation. Secretion inhibition manipulates the growth dynamics and effectively increases the quorum threshold, i.e. to develop immune responses a higher number of T cells need to be activated. Thus Treg induced secretion inhibition can provide a mechanism for tissue specific regulation of the balance between suppression (control) and immune responses, a balance that can be varied at the local tissue level through the regulation of the local active Treg population size. However, nonspecific inhibition is prone to escape of initially controlled autoimmune T cells through cross reactivity to pathogens and bystander proliferation on unrelated immune responses.     

Effect of ion channel blockers and H<Superscript>+</Superscript>-ATPase inhibitors on generation of local electrical response in a cucumber leaf

Electric potential difference was measured with extracellular electrodes between the leaf surface of 2-week-old cucumber (Cucumis sativus L.) plants and soil solution. When the leaf region with a diameter of 5 mm was gradually cooled during a 105-s period to 8–9°C, the temperature drop induced a local (confined to the cooled area) nonpropagating pulse-wise electric activity. The cessation of cooling was followed by gradual (within 12–15 min) restoration of the initial potential difference. Two peaks of electric potential with amplitudes of 100–120 mV usually appeared upon cooling. The first depolarizing stage of the pulse activity was sensitive to inhibition of voltage-gated and mechanosensitive calcium channels of plasmalemma by lanthanum and gadolinium chlorides and to verapamil treatment. Furthermore, the inhibition of this stage by ruthenium red implies the release of calcium ions from intracellular stores. The initial slow depolarization was followed by a fast depolarizing shift, which was sensitive to La³⁺ and the anion channel inhibitor 4-acetamido-4′-isothiocyano-stilbene-2,2′-dilsulfonic acid. At the next stage repolarization developed, which was sensitive to potassium channel blockers, tetraethylammonium and quinine sulfate. The influence of ion channels blockers indicates that generation of local bioelectric response is based on fluxes of the same ion species that are involved in the action potential. The depolarization stage was due to the transient Ca²⁺ influx into the cytosol from the apoplast and intracellular stores, together with the anion efflux from the cell; the repolarization stage involved potassium ions. Both stages of electric pulse generation were retarded by the H⁺-ATPase inhibitors, sodium orthovanadate and dicyclohexylcarbodiimide, which implies the involvement of the proton pump in the origin of electric pulses examined.     

The effect of neurotropic agents on evoked potentials of the association and projection regions of the cat neocortex]

Intensive non-specific inactivation of the cortex by means of its local cooling, in the cat anasthetized with nembutal, blocks in a similar way the early component of associative responses (ECAR) in the parietal area and the primary responses (PR) in the projection areas. In the case of local application of neurotropic drugs possessing specific and differentiated action on postsynaptic activity, the same ECAR changes require a somewhat higher concentration of the reagents as compared with the concentration that produces a similar PR transformation. The higher threshold of chemical sensitivity in ECAR than in the PR depends on the characteristics of the morpho-functional organization of the cortical formations. Dissimilar reactivity of the direct cortical response and of ECAR of the parietal area to the action of chemical drugs is related to the peculiarities of intracortical origin of these potentials which are due to the dissimilar nature of their generation in response to a direct and to a peripheral stimulation.     

Carbohydrates in Individual Cells of Epidermis, Mesophyll, and Bundle Sheath in Barley Leaves with Changed Export or Photosynthetic Rate

Carbohydrate metabolism of barley (Hordeum vulgare) leaves induced to accumulate sucrose (Suc) and fructans was investigated at the single-cell level using single-cell sampling and analysis. Cooling of the root and shoot apical meristem of barley plants led to the accumulation of Suc and fructan in leaf tissue. Suc and fructan accumulated in both mesophyll and parenchymatous bundle-sheath (PBS) cells because of the reduced export of sugars from leaves under cooling and to increased photosynthesis under high photon fluence rates. The general trends of Suc and fructan accumulation were similar for mesophyll and PBS cells. The fructan-to-Suc ratio was higher for PBS cells than for mesophyll cells, suggesting that the threshold Suc concentration needed for the initiation of fructan synthesis was lower for PBS cells. Epidermal cells contained very low concentrations of sugar throughout the cooling experiment. The difference in Suc concentration between control and treated plants was much less if compared at the single-cell level rather than the whole-tissue level, suggesting that the vascular tissue contains a significant proportion of total leaf Suc. We discuss the importance of analyzing complex tissues at the resolution of individual cells to assign molecular mechanisms to phenomena observed at the whole-plant level.     

Localized cooling of stems induces latewood formation and cambial dormancy during seasons of active cambium in conifers

Background and Aims In temperate regions, trees undergo annual cycles of cambial growth, with periods of cambial activity and dormancy. Environmental factors might regulate the cambial growth, as well as the development of cambial derivatives. We investigated the effects of low temperature by localized cooling on cambial activity and latewood formation in two conifers, Chamaecyparis obtusa and Cryptomeria japonica.Methods A plastic rubber tube that contained cooled water was wrapped around a 30-cm-wide portion of the main stem of Chamaecyparis obtusa and Cryptomeria japonica trees during seasons of active cambium. Small blocks were collected from both cooled and non-cooled control portions of the stems for sequential observations of cambial activity and for anatomical measurements of cell morphology by light microscopy and image analysis.Key Results The effect of localized cooling was first observed on differentiating tracheids. Tracheids narrow in diameter and with significantly decreased cambial activity were evident 5 weeks after the start of cooling in these stems. Eight weeks after the start of cooling, tracheids with clearly diminished diameters and thickened cell walls were observed in these stems. Thus, localized low temperature induced narrow diameters and obvious thickening of secondary cell walls of tracheids, which were identified as latewood tracheids. Two months after the cessation of cooling, a false annual ring was observed and cambium became active again and produced new tracheids. In Cryptomeria japonica, cambial activity ceased earlier in locally cooled portions of stems than in non-cooled stems, indicating that the cambium had entered dormancy sooner in the cooled stems.Conclusions Artificial cooling of stems induced latewood formation and cessation of cambial activity, indicating that cambium and its derivatives can respond directly to changes in temperature. A decrease in the temperature of the stem is a critical factor in the control of cambial activity and xylem differentiation in trees.     

Bioelectrical parameters of the whole human body obtained through bioelectrical impedance analysis

Knowledge of electrical properties of body tissues across the frequency spectrum is useful for tissue characterization. The bioelectric impedance analysis method, operating from 1 to 250 kHz (multi-frequency), was used in 23 normal male human subjects between the ages of 21 and 52 years, for estimation of their bioelectrical parameters. Amplitude of the output current was set to 800 microA(RMS). The experimental data showed that bioelectric parameters were highly dependent on frequency and the presence of a threshold frequency around 4 kHz. In order to explain the unusual features observed in our experimental data, the human body was simulated through the Cole-Fricke-Cole model (RC circuit) and the Extended Cole-Fricke-Cole model (RLC circuit). The simulated data showed that the Extended Cole-Fricke-Cole model had a higher accuracy than the traditional Cole-Fricke-Cole model. These results suggest that the unusual features could be due to the possible existence of inductive effects in biological cells and body tissues and that the inductive parameter and the threshold frequency could be used for characterizing the healthy tissues as well as the traditional bioelectric parameters.     

Vascular implications of Dasineura sp. galls' establishment on Peumus boldus stems

• Some chewing larvae are capable of inducing galls in the host vascular cylinder, e.g. Dasineura sp. (Cecidomyiidae) on Peumus boldus stems. Due to the medicinal and economic importance of P. boldus, the anatomical and functional implications of establishment of Dasineura sp. on P. boldus stems were investigated. We asked if establishment of Dasineura sp. in P. boldus stems induces abnormalities at the cellular and organizational level of the vascular system that increase during gall development in favour of the hydric status of the gall.
• Anatomical alterations induced in the stems during gall development were determined. Cytohistometric analyses in mature galls were compared to non-galled stems, and water potential and leaf area of non-galled stems were compared with galled stems.
• Dasineura sp. establishes in the vascular cambium, leading to delignification and rupture of xylem cells, inhibiting formation of phloem and perivascular sclerenchyma. Gall diameter increases together with larval feeding activity, producing a large larval chamber and numerous layers of nutritive tissue, vascular parenchyma, and sclerenchyma. These anatomical alterations do not affect the leaf area of galled stems but favour increased water flow towards these stems.
• The anatomical alterations induced by Dasineura sp. in P. boldus stems guarantee water and nutrient supply to the gall and larva. After the inducer exits stems, some host branches no longer have vascular connections with the plant body.

     

Induction of plant responses by a sequestering insect: Relationship of glucosinolate concentration and myrosinase activity

Induction of plant allelochemicals is of particular ecological importance for interactions with herbivores that can make use of induced metabolites by incorporating them for their own defence. Induction patterns in white mustard, Sinapis alba, were investigated following herbivory of the turnip sawfly, Athalia rosae, which sequesters plant glucosinolates. Larvae of different age were allowed to feed for 24 h on young leaves of premature, non-flowering plants. Changes in primary and secondary metabolites were recorded in the damaged leaves (local) and in the adjacent leaves and stems (systemic) for several days. Organ- and time-specific patterns were evident. Local responses included increases in glucosinolate concentrations, soluble and insoluble myrosinase activity and glucose levels, while systemic responses in leaves were restricted to increases in myrosinase activities and glucose. All effects were strongest immediately after feeding and declined mostly within a day. Stems had overall lower constitutive levels of glucosinolates and myrosinase activities than leaves. Feeding by one large larva had a greater impact on the plant's physiology than feeding by three small ones, even though both treatments resulted in quantitatively similar leaf destruction. Local increase in glucosinolate concentration could be beneficial for larvae, while conspecifics feeding on induced adjacent leaves might be negatively affected due to higher myrosinase activity levels. The results are discussed in the context of the ‘optimal defence theory’ and the ‘lethal plant defence paradox’.     

Simultaneous Measurement of the Bioelectric Potential of the Cell Wall and the Vacuoles during the Oscillatory Response to the Nitella Cell

Simultaneous measurements of bioelectric potentials of the vacuole and cell wall in cells of Nitella mucronata were made by inserting glass microelectrodes into the vacuole and cell wall respeclively. During the oscillation of the bioelectric potential of the vacuole. induced by sudden changes of the external bathing solution or by the impalement of the cell with a microelectrode. the cell wall potential also exhibited fluctuations of variable intensities in phase and concomitant with spikes of the vacuolar potential oscillation. However, the polarity of the pulses of the cell wall potential was reverse to that of the spikes of the vacuolar potential. These results suggest that the same event is registered at both sides of the plasmalemma membrane across which these phenomena are occurring. The results also support the voltage clamp and tracer flux measurements on these cells which indicate that during the generation of single action potentials, induced by current, the plasma lemma transiently increases its permeability to Cl^? and K⁺ ions expelling them from the cell. The variable intensity of the transient hyperpolarizations of the cell wall potential is explained by the distance of the microelectrode in the cell wall from the plasmalemma.     

A Pectinase-deficient Ralstonia solanacearum Strain Induces Reduced and Delayed Structural Defences in Tomato Xylem

It has been suggested that oligogalacturonides (OGAs) released by bacterial pectinases can induce plant defence responses. To test this hypothesis, resistant tomato cultivar LS-89 and susceptible cultivar Ponderosa were inoculated with either wild-type Ralstonia solanacearum strain K60 or a pectinase-deficient triple mutant K60-509, which lacks endo-polygalacturonase PehA, exo-poly-alpha- d -galacturonosidase PehB, and pectin methylesterase Pme. K60 induced structural defence responses, including electron-dense materials (EDMs) in vessels and apposition layers (ALs) in parenchyma cells adjacent to xylem vessels colonized by bacteria in LS-89 stems. In contrast, LS-89 infected with K60-509 did not have any EDMs in vessels at 4 days after inoculation (DAI), and had them only rarely at 7 DAI. In LS-89 infected with K60-509, ALs were rarely observed in parenchyma cells adjacent to vessels at 4 DAI, and while they were present at 7 DAI, they were thinner than ALs induced by K60. The bacterial density in LS-89 stems infected with K60-509 was lower than in stems infected with K60 at 4 DAI, but the strains reached similar population sizes by 7 DAI, showing the pectinase-deficient mutant colonized resistant stems more slowly than did the wild-type strain. Vessels infected with K60-509 contained fewer EDMs at 7 DAI than were observed at either 4 or 7 DAI in vessels colonized by K60, although bacterial density in the xylem tissues containing K60-509 at 7 DAI was about the same as in the xylem tissues containing K60 at 4 DAI. Neither the wild-type strain nor the pectinase-deficient mutant induced these histopathological changes on susceptible cultivar Ponderosa. These results indicate that R. solanacearum pectinases play some role in eliciting histopathological changes in LS-89, likely by releasing OGAs that trigger plant structural defences.     

Electrophysiological control of ciliary motor responses in the ctenophorePleurobrachia

Prey capture by a tentacle of the ctenophore Pleurobrachia elicits a reversal of beat direction and increase in beat frequency of comb plates in rows adjacent to the catching tentacle (Tamm and Moss 1985). These ciliary motor responses were elicited in intact animals by repetitive electrical stimulation of a tentacle or the midsubtentacular body surface with a suction electrode. An isolated split-comb row preparation allowed stable intracellular recording from comb plate cells during electrically stimulated motor responses of the comb plates, which were imaged by high-speed video microscopy. During normal beating in the absence of electrical stimulation, comb plate cells showed no changes in the resting membrane potential, which was typically about -60 mV. Trains of electrical impulses (5/s, 5 ms duration, at 5-15 V) delivered by an extracellular suction electrode elicited summing facilitating synaptic potentials which gave rise to graded regenerative responses. High K+ artificial seawater caused progressive depolarization of the polster cells which led to volleys of action potentials. Current injection (depolarizing or release from hyperpolarizing current) also elicited regenerative responses; the rate of rise and the peak amplitude were graded with intensity of stimulus current beyond a threshold value of about -40 mV. Increasing levels of subthreshold depolarization were correlated with increasing rates of beating in the normal direction. Action potentials were accompanied by laydown (upward curvature of nonbeating plates), reversed beating at high frequency, and intermediate beat patterns. TEA increased the summed depolarization elicited by pulse train stimulation, as well as the size and duration of the action potentials. TEA-enhanced single action potentials evoked a sudden arrest, laydown and brief bout of reversed beating. Dual electrode impalements showed that cells in the same comb plate ridge experienced similar but not identical electrical activity, even though all of their cilia beat synchronously. The large number of cells making up a comb plate, their highly asymmetric shape, and their complex innervation and electrical characteristics present interesting features of bioelectric control not found in other cilia.     

Role of beta adrenoceptors in metabolic and cardiovascular responses of cold exposed humans

Effect of a nonspecific beta adrenergic blocker — propranolol (40 mg per os) on thermoregulatory responses of cold water immersed (12.5°C) humans was studied. Propranolol attenuates resting and cold induced thermogenesis, rectal temperature, heart rate and systolic blood pressure, but increases production of adrenaline and cortisol. Propranolol has no effect on the threshold body temperature for induction of cold thermogenesis and on central thermosensitivity. The following conclusions are drawn from consideration of the data presented: During the early phase of cooling (20 min after the start of cooling) the thermogenesis mediated by beta adrenergic receptors may cover about 80% of the total metabolic increase induced by cold. After about 30 min of cooling the relative proportion of beta adrenergic thermogenesis starts to decline, reaching 20% of the total cold thermogenesis at the end of cooling.

It can be suggested from consideration of the data that, in man, the beta adrenergic receptors in the heart, blood vessels, adipocytes and muscles participate in mediating effect of cold on cardiovascular and thermoregulatory responses. Furthermore, these data imply that human adrenergic thermogenesis is produced outside of the brown adipose tissue. Thus, physiological mechanisms mediating adrenergic thermogenesis in humans appear to be different from those in small mammals.     

Visualization of the membrane engineering concept: evidence for the specific orientation of electroinserted antibodies and selective binding of target analytes

Membrane engineering is a generic methodology for increasing the selectivity of a cell biosensor against a target molecule, by electroinserting target‐specific receptor‐like molecules on the cell surface. Previous studies have elucidated the biochemical aspects of the interaction between various analytes (including viruses) and their homologous membrane‐engineered cells. In the present study, purified anti‐biotin antibodies from a rabbit antiserum along with in‐house prepared biotinylated bovine serum albumin (BSA) were used as a model antibody‐antigen pair of molecules for facilitating membrane engineering experiments. It was proven, with the aid of fluorescence microscopy, that (i) membrane‐engineered cells incorporated the specific antibodies in the correct orientation and that (ii) the inserted antibodies are selectively interacting with the homologous target molecules. This is the first time the actual working concept of membrane engineering has been visualized, thus providing a final proof of the concept behind this innovative process. In addition, the fluorescence microscopy measurements were highly correlated with bioelectric measurements done with the aid of a bioelectric recognition assay. Copyright © 2013 John Wiley & Sons, Ltd.     

Skin potential and EMG changes induced by cutaneous electrical stimulation. II. Subjects with reflex sympathetic dystrophies.

In a group of patients suffering from reflex sympathetic dystrophies, the skin potential and EMG responses induced by electrical stimuli applied to the skin were recorded in the four limbs in order to study somato-sympathetic and somato-motor reflexes. In most patients, the amplitude, delay and shape of the cutaneous responses as well as the pattern of the EMG responses were different from those observed in normal subjects. In particular, it was possible to correlate the pattern of the cutaneous and muscular responses with the severity of the disease. The cutaneous sensory thresholds to electrical stimuli (tactile, tingling and pain threshold) showed different values in the dystrophic and in the contralateral limb. In all patients, a block of the sympathetic chain ipsilateral to the dystrophic limb was performed with local anesthetics. 1 h after the block, the cutaneous responses disappeared not only in the blocked limb but also in the contralateral limb. 48 h after the block, muscular and cutaneous responses as well as sensory thresholds showed a pattern similar to that observed in normal subjects. These findings show that the sympathetic block provides a resetting of the sensory thresholds and reflexes.     

Correlates of choroid rete development with the metabolic potential of various tropical reef fish and the effect of strenuous exercise on visual performance

It is hypothesised that the transport of oxygen to the retinal cells of fish with Root effect haemoglobins (Hb) is impaired by strenuous exercise due to a proton load that drastically reduces arterial haemoglobin-oxygen affinity. Routinely active reef fishes have enhanced oxygen transport and anaerobic (i.e. blood lactate loading) potentials relative to inactive species. Surprisingly, the development of the choroid rete mirabile (employed as an oxygen concentrating apparatus in the eye) is directly correlated with post-exercise lactate loads rather than with the magnitude of the Root effect and suggests that an increased development is adaptive for fish with high anaerobic potentials. The hypothesis that visual performance is reduced by strenuous exercise was tested in Lutjanus carponotatus using the optomotor response. Moderate blood lactate loads (2 mmol l⁻¹ blood lactate) and red cell swelling responses were induced by exercise, but the optomotor response threshold (180 min of arc) was maintained. A moderate metabolic disturbance does not therefore appear to be a liability for the visual performance of a tropical fish in possession of Root effect haemoglobins.     

Akt and phosphoinositide regulation and wortmannin-dependent induction of phospho-Akt in 3T3-L1 adipocytes on cold exposure followed by rewarming

We exposed 3T3-L1 adipocytes to cooling followed by rewarming and examined phospho-molecule induction, including that of phospho-Akt, and the mechanism underlying the induction in these exposed cells; the viability did not deteriorate. Cooling at 4 °C increased the phospho-Thr-308 Akt level. On subsequent rewarming at 37 °C, phospho-Ser-473 Akt expression was induced in a wortmannin (PI3K inhibitor)-dependent and anisomycin (ribotoxic agent)-independent manner without decrease in the phospho-Thr-308 Akt level, and Akt-mediated phosphorylation and PI 3,4,5-trisphosphate accumulation were induced. Our results suggest that cooling followed by rewarming induces phospho-molecules through different responses of regulatory molecules, including the target molecule, to changes in temperature.     

Cooling is a potent vasodilator of deep vessels in the rat.

The objectives of this study were to determine the effect of cooling on smooth muscle tone of the pulmonary artery and aorta and to clarify the basic mechanism of these responses. We recorded isometric tension in smooth muscle strips of rat pulmonary artery and aorta in organ baths during stepwise cooling. Cooling responses were tested before and after the addition of various standard agents that interfere with known neurogenic (autonomic blockers, tetrodotoxin) and myogenic mechanisms (calcium channel blockers) of relaxation. We also examined the hypothesis of the presence of a cooling-released substance. Stepwise cooling (37degrees C to 4 degrees C) of aortic smooth muscle induced reproducible graded relaxations that were inversely proportional to temperature. Cooling-induced relaxation was not dependent on a neural mechanism nor the release of neurotransmitters or a cooling-released substance such as NO or CO. Cooling of pulmonary arterial and aortic smooth muscle preparations induced a graded myogenic relaxation inversely proportional to the cooling temperature. The mechanism is not dependent on local nervous or known mediators but related to a direct physico-chemical effect of cooling.