Expression and properties of two types of protein kinase C: alternative splicing from a single gene

Two complementary DNA's, encoding the complete sequences of 671 and 673 amino acids for subspecies of rat brain protein kinase C, were expressed in COS 7 cells. The complementary DNA sequence analysis predicted that the two enzymes are derived from different ways of splicing and differ from each other only in the short ranges of their carboxyl-terminal regions. Both enzymes showed typical characteristics of protein kinase C that responded to Ca2+, phospholipid, and diacylglycerol. The enzymes showed practically identical physical and kinetic properties and were indistinguishable from one of the several subspecies of protein kinase C that occurs in rat brain but not in untransfected COS 7 cells. Partial analysis of the genomic structure confirmed that these two subspecies of protein kinase C resulted indeed from alternative splicing of a single gene.     

Double-labeled metabolic maps of memory

The physical changes representing a memory are believed to be localized to specific neurons, widely distributed in multiple parallel pathways in the brain. 2-Fluorodeoxyglucose, labeled with two discriminable radioactive tracers, was used to construct quantitative metabolic maps in split-brain cats during a visual task. One side of the brain served to estimate the metabolic variability of nonspecific influences. The other side was used to map metabolic changes related to the presence of previously learned visual cues, as well as changes related to nonspecific influences, in the same periods of time. When the two sides were compared, between 5 million and 100 million neurons (depending upon the significance level selected) were identified in which activity increased during presentation of the familiar cues. The wide distribution of these neurons throughout the brain is compatible with prior evidence of a distributed memory system. However, the large number of neurons involved is difficult to reconcile with theories in which individual neurons are dedicated to specific memories.     

Current rectification by Pauli exclusion in a weakly coupled double quantum dot system

We observe spin blockade due to Pauli exclusion in the tunneling characteristics of a coupled quantum dot system when two same-spin electrons occupy the lowest energy state in each dot. Spin blockade only occurs in one bias direction when there is asymmetry in the electron population of the two dots, leading to current rectification. We induce the collapse of the spin blockade by applying a magnetic field to open up a new spin-triplet current-carrying channel.     

Magnetic vortex core observation in circular dots of permalloy

Spin structures of nanoscale magnetic dots are the subject of increasing scientific effort, as the confinement of spins imposed by the geometrical restrictions makes these structures comparable to some internal characteristic length scales of the magnet. For a vortex (a ferromagnetic dot with a curling magnetic structure), a spot of perpendicular magnetization has been theoretically predicted to exist at the center of the vortex. Experimental evidence for this magnetization spot is provided by magnetic force microscopy imaging of circular dots of permalloy (Ni(80)Fe(20)) 0.3 to 1 micrometer in diameter and 50 nanometers thick.     

Electronic origin of the inhomogeneous pairing interaction in the high-Tc superconductor Bi2Sr2CaCu2O8+delta

Identifying the mechanism of superconductivity in the high-temperature cuprate superconductors is one of the major outstanding problems in physics. We report local measurements of the onset of superconducting pairing in the high-transition temperature (Tc) superconductor Bi2Sr2CaCu2O8+delta using a lattice-tracking spectroscopy technique with a scanning tunneling microscope. We can determine the temperature dependence of the pairing energy gaps, the electronic excitations in the absence of pairing, and the effect of the local coupling of electrons to bosonic excitations. Our measurements reveal that the strength of pairing is determined by the unusual electronic excitations of the normal state, suggesting that strong electron-electron interactions rather than low-energy (<0.1 volts) electron-boson interactions are responsible for superconductivity in the cuprates.     

A thermally re-mendable cross-linked polymeric material

We have developed a transparent organic polymeric material that can repeatedly mend or "re-mend" itself under mild conditions. The material is a tough solid at room temperature and below with mechanical properties equaling those of commercial epoxy resins. At temperatures above 120 degrees C, approximately 30% (as determined by solid-state nuclear magnetic resonance spectroscopy) of "intermonomer" linkages disconnect but then reconnect upon cooling, This process is fully reversible and can be used to restore a fractured part of the polymer multiple times, and it does not require additional ingredients such as a catalyst, additional monomer, or special surface treatment of the fractured interface.     

Effect of cropping systems and crop successions on fumonisin levels in corn from Northern Paraná State,Brazil

In this study the effect of different cropping systems and crop successions was evaluated on natural Fusarium sp. contamination and fumonisin levels in corn. The cropping systems consisted of a conventional and no-tillage area cultivated with corn in the summer following either oats or fallow in the winter (2006 and 2007 growing seasons). In addition, the effect of applying nitrogen fertilizer (0, 22.5, 45.0, 90.0 and 90.0 kg ha⁻¹ nitrogen supplemented with potassium oxide) on fumonisin contamination was evaluated in the 2006 growing season. Fusarium sp. was detected in 90% samples in 2006 and in 100% samples in 2007. In both growing seasons, no-till corn following oats showed the highest mean fumonisin levels and differed significantly (P < 0.05) from all the others (2006) and from conventional till corn following either oats or fallow in the winter (2007). Fumonisin levels ranged from 0.13 to 19.52 μg g⁻¹ (mean 6.97 μg g⁻¹) and from 3.70 to 7.75 μg g⁻¹ (mean 6.29 μg g⁻¹) in no-till corn following oats from the 2006 and 2007 growing seasons, respectively. Plots treated with 0 kg ha⁻¹ and 22.5 kg ha⁻¹ nitrogen showed the highest mean fumonisin levels and differed significantly from those with 45.0 and 90 kg ha⁻¹ nitrogen. Fumonisin levels correlated negatively (P < 0.05) with the nitrogen fertilization rates. Although no-till is advantageous from a soil conservation standpoint, it may enhance the potential for fumonisin contamination in corn.     

Acylated and non-acylated flavonol monoglycosides from the Indian minor spice Nagkesar (Mammea longifolia)

A methanol extract of nagkesar (buds of Mammea longifolia), which showed strong radical scavenging activity, yielded 13 compounds by separations using column chromatography and HPLC. Structure elucidation of these compounds was achieved by (1)H and (13)C NMR, including DQF-COSY, TOCSY, DEPT, HMQC, HSQC, and HMBC. They include two new compounds, quercetin 3-O-(2' ',4' 'di-E-p-coumaroyl)-alpha-L-rhamno-pyranoside and quercetin 3-O-(3' ',4' '-di-E-p-coumaroyl)-alpha-L-rhamnopyranoside, along with known compounds kaempferol, quercetin, the isopropylidenedioxy derivative of shikimic acid, kaempferol 3-O-(2' ',4' '-di-E-p-coumaroyl)-alpha-L-rhamnopyranoside, kaempferol 3-O-(3' ',4' '-di-E-p-coumaroyl)-alpha-L-rhamnopyranoside, kaempferol 3-O-alpha-L-rhamnopyranoside, quercetin 3-O-alpha-L-rhamnopyranoside, shikimic acid, kaempferol 3-O-beta-D-glucopyranoside, quercetin 3-O-beta-D-glucopyranoside, and beta-sitosterol 3-O-beta-D-glucopyranoside.     

Effects of water-soluble hemicellulose from soybean hull on serum antibody levels and activation of macrophages in rats

Effects of soybean hull water-soluble hemicellulose (WSHC) on serum immunoglobulin (Ig) concentration and production of NO and IL-1beta from peritoneal macrophages were examined and compared with those of Agaricus blazei in the rat system. WSHC consisted of arabinose, galactose, xylose, glucose, and rhamnose, and the molecular weight was approximately 500000. Rats were ip administrated each sample at a dose of 0.67, 13.4, or 26.9 mg/kg/day for 14 days. The administration of WSHC resulted in significantly higher productions of IgM (p < 0.01 on day 6, p < 0.05 on day 14) and IgG (p < 0.05 on day 6) than those in other groups. When peritoneal macrophages were stimulated with various concentrations of sample (0.67, 13.4, or 26.9 mg/mL), WSHC significantly increased both NO and IL-1beta productions only at the concentration of 13.4 (mg/mL) compared with those of a saline group. These findings demonstrate that WSHC enhances humoral immunity and activation of macrophages, thereby leading to the augmentation of immune responses in rats.