Low IP Research Articles

Response of growing pigs toPeniophora lycii- andEscherichia coli-derived phytases or varying ratios of calcium to total phosphorus

AbstractTwo experiments were conducted to study the effects of phytase derived fromEscherichia coli(ECP) andPeniophora lycii(PLP) on performance, nutrient digestibility, and phosphorus (P) equivalency values of young pigs; and the influence of varying ratios of calcium (Ca) to total phosphorus (Ca:tP) with or without ECP on growth performance of pigs. In each experiment, 48 10-kg pigs were housed in individual pens for 28 days. Experiment 1 was designed to study the efficacy of ECP and PLP in improving growth performance and bone mineralization of young pigs given a low inorganic P (iP) diet. In the experiment, pigs were blocked by weight and sex and randomly allocated to eight dietary treatments. Each treatment had six replicates. The treatments were a positive control with adequate iP (PC); a low iP negative control (NC) diet; NC with supplemental iP in the form of monosodium phosphate added to provide 0·75 or 1·50 g iP per kg diet (as-fed basis); NC with ECP or PLP added at 500 or 1000 FTU per kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 μmol of iP per min, at pH 5·5, from an excess of 15 μmol/l sodium phytate at 37°C). In experiment 2, the objective was to study the effect of varying Ca:tP ratio with or without ECP on growth performance of growing pigs. Pigs (eight replicates) were blocked by weight and sex and randomly assigned to six dietary treatments in a 3×2 factorial arrangement of Ca:tP ratios at 1·2, 1·5, or 1·8; and ECP at 0 or 1000 FTU per kg (as-fed basis). In experiment 1, ECP (P<0·001) and PLP (P<0·05) linearly increased daily gain. There was a positive linear (P<0·05) response to the supplementation of the NC diet with ECP or PLP in the mineralization of the third and fourth metacarpal bones. Phosphorus equivalency values for 500 FTU of ECP or PLP based on mineralization of the third metacarpal bone were 0·77 g or 0·572 g, respectively. There were linear (P<0·001) and quadratic (P<0·05) responses to ECP, and linear (P<0·01) response to PLP in P digestibility. Neither iP supplementation nor either of the two phytases had significant effects on digestibility of dry matter, protein or energy. In experiment 2, reducing Ca:tP ratio linearly improved (P<0·05) daily gain, food intake, and food efficiency in pigs regardless of phytase supplementation. There was an enzyme by Ca:tP interaction on food intake. These studies in young pigs showed that ECP and PLP were efficacious in improving the growth performance and bone mineralization and that reducing the Ca:tP ratio enhanced performance response to phytase supplementation.

Interplanetary hydrogen absolute ionization rates: Retrieving the solar wind mass flux latitude and cycle dependence with SWAN/SOHO maps

We present results of the total hydrogen ionization rate obtained from the inversion of almost 10 years of full‐sky maps of the interplanetary Lyman α background measured by the SWAN instrument on SOHO. Thanks to a new estimate of the absolute calibration of the SWAN instrument and its variation during the 10 years of operation of SOHO, we are able to derive absolute values of the ionization rate as well as its latitudinal dependence. We show how the anisotropy of the ionization rate changes from solar minimum to solar maximum. At solar maximum, the so‐called ionization groove has completely disappeared and the ionizing fluxes are the same at all heliographic latitudes. We find that the hydrogen ionization cavity which surrounds the Sun increases in size with solar activity. This is evidenced by the low IP Lyman α intensities measured during and after the solar maximum. Our model calculation also shows that the increased radiation pressure is not sufficient to explain the larger cavity observed at solar maximum. We find also that ionization rates derived from in situ solar wind measurements do agree with the SWAN results at solar minimum but are significantly smaller at solar maximum. Derived in situ ionization rates do not show the solar cycle dependence we see from the SWAN data. In conclusion, we discuss possible explanations for this discrepancy.

Long pulse high performance plasma scenario development for the National Spherical Torus Experiment

The National Spherical Torus Experiment [Ono et al., Nucl. Fusion, 44, 452 (2004)] is targeting long pulse high performance, noninductive sustained operations at low aspect ratio, and the demonstration of nonsolenoidal startup and current rampup. The modeling of these plasmas provides a framework for experimental planning and identifies the tools to access these regimes. Simulations based on neutral beam injection (NBI)-heated plasmas are made to understand the impact of various modifications and identify the requirements for (1) high elongation and triangularity, (2) density control to optimize the current drive, (3) plasma rotation and/or feedback stabilization to operate above the no-wall β limit, and (4) electron Bernstein waves (EBW) for off-axis heating/current drive (H/CD). Integrated scenarios are constructed to provide the transport evolution and H/CD source modeling, supported by rf and stability analyses. Important factors include the energy confinement, Zeff, early heating/H mode, broadening of the NBI-driven current profile, and maintaining q(0) and qmin>1.0. Simulations show that noninductive sustained plasmas can be reached at IP=800 kA, BT=0.5 T, κ≈2.5, βN⩽5, β⩽15%, fNI=92%, and q(0)>1.0 with NBI H/CD, density control, and similar global energy confinement to experiments. The noninductive sustained high β plasmas can be reached at IP=1.0 MA, BT=0.35 T, κ≈2.5, βN⩽9, β⩽43%, fNI=100%, and q(0)>1.5 with NBI H/CD and 3.0 MW of EBW H/CD, density control, and 25% higher global energy confinement than experiments. A scenario for nonsolenoidal plasma current rampup is developed using high harmonic fast wave H/CD in the early low IP and low Te phase, followed by NBI H/CD to continue the current ramp, reaching a maximum of 480 kA after 3.4 s.

Nonvisual Arrestin Oligomerization and Cellular Localization Are Regulated by Inositol Hexakisphosphate Binding

Interactions between arrestins and phosphoinositides have been reported to regulate multiple membrane-associated signaling and trafficking events including clathrin-mediated endocytosis and light adaptation in Drosophila. Arrestins have been proposed to have nuclear and cytosolic functions as well, although the ligand dependence of these functions has not been investigated. Here we characterize the structural, molecular, and cellular interactions between arrestin-2 and inositol hexakisphosphate (inositol 1,2,3,4,5,6-hexakisphosphate (IP(6))). The crystal structure of the arrestin-2.IP(6) complex was solved to 2.9 A with crystal lattice contacts suggesting two sites on a protein monomer mediating IP(6) binding. Mutagenesis coupled to isothermal titration calorimetry and tritiated IP(6) binding assays confirmed two-site binding with a low affinity IP(6)-binding site in the N-domain and a high affinity site in the C-domain. Native gel electrophoresis, gel filtration, and analytical ultracentrifugation demonstrated the ability of IP(6) to promote arrestin-2 oligomerization via the two crystallographically defined ligand-binding locations. In addition, analysis in mammalian cells revealed that arrestin-2 not only undergoes homo-oligomerization, but it can also hetero-oligomerize with arrestin-3 in a manner that depends on IP(6)-binding sites. Mutation of either IP(6)-binding site in arrestin-2 disrupted oligomerization while interactions with known binding partners including clathrin, AP-2, and ERK2 were maintained. Subcellular localization studies showed that arrestin-2 oligomers are primarily cytoplasmic, whereas arrestin-2 monomers displayed increased nuclear localization. Thus, by promoting cytosolic oligomerization, IP(6) binding is proposed to be a negative regulator of interactions of arrestin with plasma membrane and nuclear signaling proteins.

Stabilizing Role of Calcium Store-Dependent Plasma Membrane Calcium Channels in Action-Potential Firing and Intracellular Calcium Oscillations

In many biological systems, cells display spontaneous calcium oscillations (CaOs) and repetitive action-potential firing. These phenomena have been described separately by models for intracellular inositol trisphosphate (IP 3)-mediated CaOs and for plasma membrane excitability. In this study, we present an integrated model that combines an excitable membrane with an IP 3-mediated intracellular calcium oscillator. The IP 3 receptor is described as an endoplasmic reticulum (ER) calcium channel with open and close probabilities that depend on the cytoplasmic concentration of IP 3 and Ca 2+. We show that simply combining this ER model for intracellular CaOs with a model for membrane excitability of normal rat kidney (NRK) fibroblasts leads to instability of intracellular calcium dynamics. To ensure stable long-term periodic firing of action potentials and CaOs, it is essential to incorporate calcium transporters controlled by feedback of the ER store filling, for example, store-operated calcium channels in the plasma membrane. For low IP 3 concentrations, our integrated NRK cell model is at rest at −70 mV. For higher IP 3 concentrations, the CaOs become activated and trigger repetitive firing of action potentials. At high IP 3 concentrations, the basal intracellular calcium concentration becomes elevated and the cell is depolarized near −20 mV. These predictions are in agreement with the different proliferative states of cultures of NRK fibroblasts. We postulate that the stabilizing role of calcium channels and/or other calcium transporters controlled by feedback from the ER store is essential for any cell in which calcium signaling by intracellular CaOs involves both ER and plasma membrane calcium fluxes.

Low IP area and left periphery in Mandarin Chinese

L’hypothèse de Belletti (2003), selon laquelle l’architecture fonctionnelle à l’intérieur d’IP reflète celle au-dessus d’IP, est examinée pour le mandarin. Tandis que le parallélisme entre CP et la partie basse d’IP se trouve confirmé, la hiérarchie obtenue pour le mandarin, ‘CP (force) > TopP > FocusP ‘même’ > IP > TopP interne > FocusP ‘même’ > vP’, ne correspond que partiellement à celle proposée par Rizzi (1997, 2002) et Belletti (2003), surtout en ce qui concerne l’ordre relatif entre topique et focus. En effet, en mandarin un TopP au-dessous de FocusP est exclu aussi bien dans CP que dans IP et il n’y a pas non plus de ModP dans la périphérie gauche, projection introduite par Rizzi (2002) pour abriter des adverbes déplacés. Ces différences s’expliquent partiellement par l’idée reçue que le topique véhicule toujours de l’ancienne information, idée clairement infirmée par le mandarin.

Comprehensive On-Line Characterization of Complex Gas Mixtures by Quasi-Simultaneous Resonance-Enhanced Multiphoton Ionization, Vacuum-UV Single-Photon Ionization, and Electron Impact Ionization in a Time-of-Flight Mass Spectrometer: Setup and Instrument Characterization

This paper reports on a newly developed mobile mass spectrometer for comprehensive on-line analysis of complex gas mixtures such as ambient air or industrial process gases. Three ionization methods, namely, the resonance-enhanced multiphoton ionization (REMPI), vacuum-ultraviolet single-photon ionization (SPI), and electron impact ionization (EI) are implemented in this instrument and can be operated (quasi-) simultaneously. By means of this setup, a wide range of compounds can be analyzed due to the unique ionization selectivitiy and sensitivity profiles provided by the different ionization techniques. The mass spectrometer is designed for field application even under severe conditions. The REMPI technique is suitable for the selective and soft ionization (without fragmentation) of aromatic compounds at trace level (ppbv/pptv). The also soft but less selective SPI technique with 118-nm vacuum-ultraviolet laser pulses is used as a second laser-based ionization method. Mass spectra obtained by this technique show profiles of most organic compounds (aliphatic and aromatic species) and of some low IP inorganic substances (e.g., ammonia, nitrogen oxide) down to ppbv concentrations. In addition to the laser-based ionization techniques, EI ionization can be used for analysis of the bulk components such as water, oxygen, nitrogen, and carbon dioxide as well as for detection of inorganic minor components such as HCN or HCl from combustion flue gases at ppmv concentration levels. Each method yields specific mass spectrometric information of the sample composition. Special techniques have been developed to combine the three ionization methods in a single mass spectrometer and to allow the quasi-parallel application of all three ionization techniques.

Efficient Optimization Strategy for Marginal Hits Active Against abl Tyrosine Kinases

Primary high-throughput screening of commercially available small molecules collections often results in hit compounds with unfavorable ADME/Tox properties and low IP potential. These issues are addressed empirically at follow-up lead development and optimization stages. In this work, we describe a rational approach to the optimization of hit compounds discovered during screening of a kinase focused library against abl tyrosine kinase. The optimization strategy involved application of modern chemoinformatics techniques, such as automatic bioisosteric transformation of the initial hits, efficient solution-phase combinatorial synthesis, and advanced methods of knowledge-based libraries design.

A wave of IP 3 production accompanies the fertilization Ca 2+ wave in the egg of the frog, Xenopus laevis: theoretical and experimental support

The fertilization Ca 2+ wave in Xenopus laevis is a single, large wave of elevated free Ca 2+ that is initiated at the point of sperm–egg fusion and traverses the entire width of the egg. This Ca 2+ wave involves an increase in inositol-1,4,5-trisphosphate (IP 3) resulting from the interaction of the sperm and egg, which then results in the activation of the endoplasmic reticulum Ca 2+ release machinery. The extraordinarily large size of this cell (1.2 mm diameter) together with the small surface region of sperm-receptor activation makes special demands on the IP 3-dependent Ca 2+ mobilizing machinery. We propose a detailed model of the fertilization Ca 2+ wave in Xenopus eggs that requires an accompanying wave of IP 3 production. While the Ca 2+ wave is initiated by a localized increase of IP 3 near the site of sperm–egg fusion, the Ca 2+ wave propagates via IP 3 production correlated with the Ca 2+ wave—possibly via Ca 2+-mediated PLC activation. Such a Ca 2+-mediated IP 3 production wave has not been required previously to explain the fertilization Ca 2+ wave in eggs; we argue this is necessary to explain the observed IP 3 dynamics in Xenopus eggs. To test our hypothesis, we have measured the IP 3 levels from 20 nl “sips” of the egg cortex during wave propagation. We were unable to detect the low IP 3 levels in unfertilized eggs, but after fertilization, [IP 3] ranged from 175 to 430 nM at the sperm entry point and from 120 to 700 nM 90° away once the Ca 2+ wave passed that region about 2 min after fertilization. Prior to the Ca 2+ wave reaching that region the IP 3 levels were undetectable. Since significant IP 3 could not diffuse to this region from the sperm entry point within 2 min, this observation is consistent with a regenerative wave of IP 3 production.

Control of the Locked Mode in a Reversed-Field Pinch Plasma Using a Rotating Toroidal Field

The locked mode (LM), which is locked both in phase and to the wall, is successfully controlled using a rotating toroidal field (RTF) in TPE-RX (large reversed-field pinch machine with R/a = 1.72 m/0.45 m and plasma current Ip up to 480 kA) at a low Ip (∼200 kA) and high filling pressure (∼0.8 mTorr). It is demonstrated that the onset of the LM can be delayed or even eliminated by applying the RTF. Only the Fourier component with m=0/n=1 of the magnetic fluctuation exhibits rotation with the RTF, but other modes do not exhibit systematic movement synchronizing with the m=0/n=1 mode rotation. The phase relation between the m=0/n=1 mode and the other modes becomes random, which probably prevents the phases of the other modes from locking and results in the elimination of the LM. It is found, however, after the LM has taken place, it cannot be controlled by the RTF and hence an early start and fast rotation of the RTF are required for control. It is not possible to control the LM at a high Ip (\\gtrsim250 kA), since the LM takes place from the early stage of discharge. Compared with discharges without the LM, plasma performance is degraded by the LM. The performance can be recovered by eliminating the LM with the RTF. However, the RTF itself degrades the plasma performance when applied to LM-free discharges with a RTF value comparable to that necessary for controlling the LM.

Inositol phosphate degradation by the action of phytase enzyme in legume seeds

The kinetics of inositol phosphate degradation during the action of naturally occurring endogenous phytase for up to 90 min in pea and lentil flours has been studied, and compared with the addition of commercial phytase enzyme. In raw lentils IP 6, IP 5, IP 4 and IP 3 were present, whilst in peas only the presence of IP 6 and IP 5 was observed. Endogenous phytases were activated when legume flour was suspended in acidified water at pH 5.5 and 37 °C, and significant differences between lentils and peas were found. IP 6 suffered a sharp reduction in lentils and peas (81–91 and 73–93%, respectively), this reduction being slightly more pronounced after the addition of commercial phytase. The content of IP 5 decreased in lentils (48–69%), and increased in peas, except when commercial phytase acted for the first 30 min, after which a reduction was found (23%). The content of IP 4 generally decreased in lentils, except when endogenous phytase acted for 30 min when an increase was observed. However, in peas, IP 4 appeared in high concentrations up to 60 min by the action of both endogenous and exogenous phytases. The content of IP 3, on the other hand, did not change greatly in lentils. In peas it was not detected after the action of endogenous phytase enzyme and it appeared in a large amount after the action of commercial phytase. In order to obtain legume flour with low IP 6 and IP 5 contents and notable IP 4 and IP 3 contents, the action of naturally endogenous phytase for 30 min in lentils is recommendable, as well as the addition of commercial phytase enzyme for 60 min in peas.

Optical Layer Protection of ATM Traffics using a Novel 4-Fiber WDM Ring with an Ability to carry Extra Traffic

ATM/IP directly over WDM ring with optical layer protection is proposed and demonstrated. Traffics are 1+1 protected ATM OC-48c and a low priority part-time OC-48c IP traffic. When either fiber or cable failure occurs, optical layer protection can restore the ATM traffic via optical layer span/ring protection within 13 ms/23 ms while the part-time traffic is dropped. A faster protection time comparing with SONET standard is experimentally verified by both physical layer and ATM layer test results.

Near thermal energy collisions with fullerenes: a generally applicable soft ionization method for low IP molecules?

Sodium clusters were derivatized via reaction with SF 6 or O 2 to generate supersonic molecular beams containing Na x F y /Na x SF y or Na x O 2/Na x O ( x ≤ 10), respectively. These mixed clusters were collided with a C 60 effusive beam at center of mass kinetic energies in the near thermal regime. Under single collision conditions and in the absence of external light sources, strong cation and anion signals were observed—as detected by mass spectroscopy. Signals are due to resonant electron transfer and concomitant ion pair formation in analogy to previous observations for bare sodium cluster beams. Energetic considerations allow the determination of upper bounds to the appearance potentials of various mixed cluster cations. Comparison to photoionization mass spectra, indicates that such collisional ionization can be relatively soft and is associated with large cross sections even for ionically bound rather than “metallic” electron donors—suggesting that the method may be generally applicable for mass spectroscopy of low IP species.

Recent Progress in JT-60U Experiments with W-Shaped Divertor

Recent experimental results of power and particle control in JT-60U with W-shaped pumped divertor are presented. Backflow of carbon impurities towards x point is decreased by the dome as well as by the gas puff from the main plasma. Heat load on divertor plates is reduced by the detached plasma at high density and radiative plasma by neon seeding. Effective helium exhaust is demonstrated for helium-beam-injected plasmas. Results of high-confinement experiments are also shown. Strongly heated ELMy H-mode plasmas are sustained during 9 s without increasing the impurity contamination. High QDTeq ~ 1 is obtained in the low Ip regime of the reversed shear plasmas. Progress in the negative-ion-based neutral beam injection experiments is finally introduced

The expression of proliferating antigen Ki67 and PCNA and products of suppressor gene p53 in primary invasive ductal carcinoma of female breast

The aim of the study was to examine the consecutive series of primary ductal invasive tumoure and fincl out: a) the expression of some biological cellular parameters as proliferating antigens Ki67 and PCNA and products of suppressor gene ~53; b) correlation between the levels of expression of those factors and classical prognostic factors. In 1994 eighty eight woman were operated for primary ductal carcinoma of the breast. The material used in the study: a) tissue samples fixed in 10% buffer formaline and paraffin embedded; b) tissue samples of the same turnours to estimate levels of steroids receptors. We used monoclonal antibodies (Dakopatts). The examination of steroids receptors was done with the usage of immunoenzymatic ELISA method. The kinetics for nuclear antigens: Ki67, PCNA, ~53, defined as index, has been estimated with half-quantitative method with the usage of Hogg’s grating (number of positive cells/1000 cells in 10 microscopic fields). The estimation has been done by two pathologists and the final result has been reported as arithmetical mean. Results: 1. High index IP PCNA, Ki67, I p53 and low levels of steroids receptors correlates with high histological malignancy (Bloom Ill); 2. Low index IP PCNA, Ki67, I ~53 correlates with high levels of steroids receptors; 3. The estimation of high levels of index IP PCNA, IP Ki67 can be helpful for separate tumours of high proliferating activity; 4. High index of I ~53 do not correlate with the diameter of tumour and with involvement of axillary lymph nodes; 5. It seems that the estimation of proliferating antigens together with products of suppressor gene ~53 might have greater prognostic value than the estimation of single of those factors.

Designing low-ionization potential analogs of tetrakis-dimethylamino-ethylene using density functional calculations

A number of analogs of the photosensitive molecule TMAE (tetrakis-dimethylamino-ethylene) have been investigated computationally with the goal of lowering the vertical ionization potential (IP v). This is of importance in UV-photodetectors based on gas photoionization and multiplication. The low IP v of TMAE, 6.11 eV, is shown to be due to resonance stabilization of the cation. N-substitution of phenyl groups and p-substitution of tertiary amines on the latter are found to be efficient ways of lowering IP v. The compound trans-bis-( p-dimethylaminophenyl, methyl)aminoethylene is calculated to have a IP v considerably lower than TMAE (∼ 5.5–5.7 eV) and appears to be a promising synthetic target.

Coupled Reactions of Condensation and Charge Transfer. 1. Formation of Olefin Dimer Ions in Reactions with Ionized Aromatics. Gas-Phase Studies

The toluene radical ion C6H5CH3•+, generated by resonance two-photon ionization, does not react with a single isobutene molecule (i-C4H8) which has a significantly higher ionization potential (ΔIP = 0.42 eV). However, a reaction is observed involving two i-C4H8 molecules, to form the dimer ion C8H16•+. A coupled reaction of dimer formation and charge transfer to the dimer is exothermic if the product is an ionized hexene with a low IP. Correspondingly, the observed nominal second-order rate coefficients, (5−25) × 10-12 cm3 s-1, are enhanced by a factor of >105 over the expected value for direct endothermic charge transfer. Pressure and concentration effects suggest a sequential mechanism that proceeds through a C6H5CH3•+(i-C4H8) reactive π complex. The complex can isomerize to a nonreactive CH3C6H4-t-C4H9•+ adduct, or react with a second i-C4H8 molecule to form a C6H5CH3•+(i-C4H8)2 complex, in which the olefin molecules are activated by the aromatic ion. Similar reactions are observed in the benzene/propene system with a somewhat larger ΔIP of 0.48 eV, suggesting that the charge density on the olefin in the complex is still sufficient to activate it for nucleophilic attack. However, aromatic/olefin systems with ΔIP > 0.87 eV show no olefin dimer formation. At low [i-C4H8] and [Ar] number densities, the rate of formation of C8H16•+ is proportional to [i-C4H8]2[Ar]. The corresponding fourth-order rate coefficient shows a strong negative temperature coefficient with k = 11 × 10-42 cm9 s-1 at 300 K and 2 × 10-42 cm9 s-1 at 346 K, suggesting that the mechanism can be efficient in low-temperature industrial and interstellar environments. The direct formation of the dimer bypasses the monomer olefin cation and its consequent side-reactions, and directs the products selectively into radical ion polymerization. The products and energy relationships that apply in the gas phase are observed also in clusters.

Molecular design of hole transport materials for obtaining high durability in organic electroluminescent diodes

The molecular design of hole transport materials (HTMs) for producing high durability in organic layered electroluminescent (EL) diodes was elucidated. The durability tests were examined using fourteen hole transport materials in the cell structure of an anode/hole transport layer (HTL)/emitter layer (EML)/cathode. The ionization potential (Ip) of HTLs was found to be the dominant factor for obtaining high durability in organic EL devices. The formation of the small energy barrier at the interface of a HTL/anode was required for high durability. Moreover, no straightforward relations between melting point, glass transition temperature of the HTMs, and durability of the EL devices were observed. The EL device using the HTM having a low Ip (5.08 eV) showed an especially remarkable stability. In this case, the half-life period of the initial luminance was beyond 500 h.

Applications of work function microscopy in the onset mode

Work function spectroscopy (WFS) in a microprobe mode (scanning work function microscopy SWFM), or in conjunction with sputter depth profiling constitutes a useful supplementary method to other surface analytical techniques. The so-called onset technique of WFS utilizes the influence of the electronic work function Φ of the sample on the onset of the energy distribution of the “true” secondary electrons. This technique can readily be incorporated into existing surface analytical instruments like Scanning Auger microprobes. WFS and Auger electron spectroscopy (AES) have been applied in-situ during sputter depth profiling of sulphur layers segregated on top of Cu(111), and of implantation profiles of Cs+ bombarded Si(111) with Ar+ ions of 1 keV. Because the onset technique for WFS takes advantage of the high intensity of the “true” secondary electrons, it is possible to use very low primary electron currents Ip. Employing a commercial instrument (PHI SAM 660) with a minimum spot size of 20 nm a lateral resolution of about 25 nm is achieved in the SWFM mode.

The nuclear inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate receptors

IP 3R is located to the inner nuclear membrane. Nuclear IP 3R is recognized as a 220 kD immunoreactive protein by antisera raised against purified rat brain IP 3R. Antisera against C-terminal 95–108 peptide fragment derived from rat brain IP 3R does not reveal immunoreactivity in the nucleus. Nuclear IP 3R is sensitive to heparin and is phosphorylated by nuclear PKC, enhancing the efficiency of IP 3 in nuclear calcium release. There are two IP 4 binding sites located to the nuclear envelope. The nuclear IP 4R is sensitive to pH and pH 6.5 is found optimum for the ligand binding. The high affinity IP 4R is associated with the outer nuclear membrane and mediates nuclear calcium uptake by IP 4. Low affinity IP 4R is identified with the inner nuclear membrane and is not involved in IP 4 mediated calcium entry into the nucleus. The nature of IP 4R associated with the outer nuclear membrane as compared with the one identified with the inner nuclear membrane remains to be elucidated.