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The optical response of the lowest-energy isomers of the B20 family is calculated using time-dependent density-functional theory within a real-space, real-time scheme. Significant differences are found among the absorption spectra of the clusters studied. We show that these differences can be easily related to changes in the overall geometry. Optical spectroscopy is thus an efficient tool to characterize the planar-to-tubular structural transition, known to be present in these boron-based systems.

Anal atresia is a relatively common congenital malformation that occurs in about 1 out of 5000 infants, caused by abnormal hindgut development of the embryo, often associated with other developmental anomalies (e.g., Currarino, Townes-Brock, Pallister-Hall syndromes, and VATER association). Genetic analysis in human families is exceedingly difficult due to the multifactorial nature of the trait. In pigs, anal atresia occurs at a higher incidence (0.18%) than in humans. A complete genome scan (165 microsatellite markers) was performed using a backcross pedigree previously obtained by crossing affected animals from a partially inbred line, selected for a high incidence of anal atresia, with an unaffected male of a different breed (Meishan). The data set was analyzed with classical linkage (TWOPOINT) and nonparametric genetic methods (NPL, Non-Parametric Linkage, and TDT, Transmission Disequilibrium Test). Both methods support association of the trait with two loci on Chromosomes 9 and 15. GLI2 (GLI-Kruppel family member GLI2) was identified as a positional candidate gene based on comparative mapping; radiation hybrid mapping confirmed that this locus is located within the QTL region.

Bifunctional derivatives of the alkaloid galanthamine, designed to interact with both the active site of the enzyme acetylcholinesterase (AChE) and its peripheral cation binding site, have been assayed with Torpedo californica AChE (TcAChE), and the three-dimensional structures of their complexes with the enzyme have been solved by X-ray crystallography. Differences were noted between the IC(50) values obtained for TcAChE and those for Electrophorus electricus AChE. These differences are ascribed to sequence differences in one or two residues lining the active-site gorge of the enzyme. The binding of one of the inhibitors disrupts the native conformation of one wall of the gorge, formed by the loop Trp279-Phe290. It is proposed that flexibility of this loop may permit the binding of inhibitors such as galanthamine, which are too bulky to penetrate the narrow neck of the gorge formed by Tyr121 and Phe330 as seen in the crystal structure.

This empirical investigation tested the hypothesis that the benefits of personal choosing are restricted to choices made from among attractive alternatives. Findings from vignette and laboratory studies show that contrary to people's self-predictions prior to actually choosing, choosers only proved more satisfied than nonchoosers when selecting from among more preferred alternatives. When selecting from among less preferred alternatives, nonchoosers proved more satisfied with the decision outcome than choosers. Subsequent analyses revealed that differences in outcome satisfaction between choosers and nonchoosers emerge even before the decision outcome is experienced and that interventions during the decision-making process can serve to attenuate these differences. Theoretical and practical implications are discussed., (((c) 2004 APA, all rights reserved))

Plants of Trifolium spp. exhibiting two different kinds of symptoms--phyllody associated with yellowing/reddening, and dwarf growth habit without floral abnormalities--were observed in several areas of the Czechia. Nested polymerase chain reaction (PCR) with phytoplasma specific primers, and restriction fragment length polymorphism (RFLP) analyses of 16SrDNA revealed that phyllody of T. repens was associated with phytoplasmas belonging to the 16SrI-C subgroup. Similar symptoms in T. hybridum and T. pratense plants revealed the presence of phytoplasmas belonging to two subgroups: 16SrI-C and 16SrIII-B. Dwarf disease of cultivated T. pratense plants was associated with more than one agent: 11 of 20 plants examined by PCR/RFLP analysis revealed the presence of phytoplasmas belonging to four distinct subgroups: 16SrI-B, 16SrI-C, 16SrIII-B and 16SrX-A. Moreover, two kinds of bacilliform virions were observed in ultrathin sections of 15 T. pratense plants. Particles occurred mostly in the parenchymatous cells of vascular bundles and were located in the cytoplasm as aggregates within an extended network of membranous cisternae. Phytoplasmas and rhabdoviruses occurred singly, and both together or in co-presence with filamentous virus-like particles.

Drosophila gliotactin (Gli) is a 109-kDa transmembrane, cholinesterase-like adhesion molecule (CLAM), expressed in peripheral glia, that is crucial for formation of the blood-nerve barrier. The intracellular portion (Gli-cyt) was cloned and expressed in the cytosolic fraction of Escherichia coli BLR(DE3) at 45 mg/L and purified by Ni-NTA (nitrilotriacetic acid) chromatography. Although migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), under denaturing conditions, was unusually slow, molecular weight determination by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) confirmed that the product was consistent with its theoretical size. Gel filtration chromatography yielded an anomalously large Stokes radius, suggesting a fully unfolded conformation. Circular dichroism (CD) spectroscopy demonstrated that Gli-cyt was >50% unfolded, further suggesting a nonglobular conformation. Finally, 1D-(1)H NMR conclusively demonstrated that Gli-cyt possesses an extended unfolded structure. In addition, Gli-cyt was shown to possess charge and hydrophobic properties characteristic of natively unfolded proteins (i.e., proteins that, when purified, are intrinsically disordered under physiologic conditions in vitro)., (Copyright 2003 Wiley-Liss, Inc.)

Aims: Partial genetic characterization of several chromosomal regions on 35 16SrI-B phytoplasma strains maintained in periwinkle and collected in different geographical areas from plants of diverse species., Methods and Results: Genes coding for ribosomal protein rpL22, elongation factor EF-Tu and random cloned sequences amplified with primers AY19p/m, G35p/m and BB88F1/R1 after RFLP analyses showed a high degree of polymorphism among the strains studied. The ribosomal protein (rp) subgroups B and K, and an undescribed subgroup designated N, were identified. Amplicons obtained with primers AY19p/m and BB88F1/R1, revealed a high and a low degree of polymorphism, respectively., Conclusions: A probable spacer role could be attributed to the AY19p/m sequence and a possible coding function to the BB88F1/R1 sequence. No relationship was found among genetic polymorphisms, identified by statistical analyses, and epidemiological or biological parameters., Significance and Impact of the Study: The analyses of five different genomic sequences of the 35 strains belonging to subgroup 16SrI-B allowed a finer distinction among them, confirming that the polymorphism level of 16S rDNA is too low to be adopted as unique parameter for classification.

The static dielectric properties of (001)(GaAs)(p)/(AlAs)(p) superlattices have been calculated as a function of their period p for 1< or = p < or =12, starting from density-functional theory. The interplay between quantum confinement and local field effects is shown to be crucial. For light polarized in the growth direction it leads to the otherwise surprising justification of the use of a classical effective medium theory, even for the smallest periods. Only the inclusion of both contributions allows in ab initio and in semiempirical calculations to reproduce the experimentally observed birefringence.

Flavescence dorée is a devastating disease of grapevine widespread in several countries in EU such as France, Italy and Spain. Genetic variability among 17 Italian and 3 French FD strains was investigated by RFLP analyses based on a fragment of the ribosomal protein operon and on the non-ribosomal DNA fragment FD9. RFLP analysis of the PCR amplified ribosomal protein fragment, coding for the 3' end of rpl22 and the entire rps3 genes, differentiated 4 rp-subgroups among the FD strains and 4 subgroups among the reference strains belonging to elm yellows group (16SrV). Sequencing and phylogenetic analysis of the same ribosomal protein DNA fragment validated the delineation of 4 distinct FD strain types derived by RFLP analyses. The results supported the differentiation based on analysis of the non-ribosomal DNA fragment FD9. The phylogenetic analysis further revealed relationships and a probable evolutionary trend among the FD strains and the other representatives of elm yellows group. All the FD strains together with the reference strains ALY, RuS and JWB formed a cluster very well distinct from the EY/ULW cluster. Moreover, ALY was shown to be more closely related to three FD strain types: the Lombardia/Piemonte, the French FD70, and the French FD88/Italian FD-D strain clusters.

Background: The complementarity determining region 3 (CDR3) of the immunoglobulin (Ig) heavy chain variable region (VH) is the most reliable molecular fingerprint for most if not all human B cells. The nucleotide sequence encoding for any B-cell tumor-specific VH CDR3 is currently identified by PCR sequencing based on procedures involving the usage of either radioactive materials, patient/family-specific primers, or bacterial cloning., Patients and Methods: In six consecutive patients with follicular lymphoma we assessed the feasibility of a method that allows for identification of the tumor-specific VH CDR3 using consensus primers while avoiding both radioactive materials and bacterial cloning procedures., Results: The tumor-specific VH CDR3 was successfully identified in all six patients in nearly half the time typically required by any other method currently utilized. The feasibility of the proposed method was not significantly affected either by the tumor-specific Ig isotype, or by the tumor infiltration in the original biopsy specimen. In the three patients for whom tumor specimen-derived hybridomas were available, the tumor-specific VH CDR3 was also found in at least 8 of 10 of them., Conclusions: The proposed method allows the ability to quickly identify the B-cell tumor-specific VH CDR3 using consensus primers while avoiding radioactive materials and bacterial cloning procedures.

We present a model for the molecular traffic of ligands, substrates, and products through the active site of cholinesterases (ChEs). First, we describe a common treatment of the diffusion to a buried active site of cationic and neutral species. We then explain the specificity of ChEs for cationic ligands and substrates by introducing two additional components to this common treatment. The first module is a surface trap for cationic species at the entrance to the active-site gorge that operates through local, short-range electrostatic interactions and is independent of ionic strength. The second module is an ionic-strength-dependent steering mechanism generated by long-range electrostatic interactions arising from the overall distribution of charges in ChEs. Our calculations show that diffusion of charged ligands relative to neutral isosteric analogs is enhanced approximately 10-fold by the surface trap, while electrostatic steering contributes only a 1.5- to 2-fold rate enhancement at physiological salt concentration. We model clearance of cationic products from the active-site gorge as analogous to the escape of a particle from a one-dimensional well in the presence of a linear electrostatic potential. We evaluate the potential inside the gorge and provide evidence that while contributing to the steering of cationic species toward the active site, it does not appreciably retard their clearance. This optimal fine-tuning of global and local electrostatic interactions endows ChEs with maximum catalytic efficiency and specificity for a positively charged substrate, while at the same time not hindering clearance of the positively charged products.

Recently it was demonstrated that the metabolism of both glycoproteins and sphingo(glyco)lipids is dependent upon the state of enterocytic differentiation of HT-29 cells. Furthermore, it was shown that undifferentiated HT-29 cells display an important autophagic sequestration, controlled by a heterotrimeric Gi3 protein. In order to correlate the metabolism of sphingo(glyco)lipids with the extent of autophagic sequestration, we have incubated undifferentiated and differentiated HT-29 cells with tritium-labelled GM1 ganglioside and sphingosine in the absence and presence of pertussis toxin (an inhibitor of autophagic sequestration) or asparagine (an inhibitor of autophagic vacuole maturation). In addition, undifferentiated HT-29 cells transfected with a cDNA encoding the G alpha i3 protein (cells expressing an amplified autophagic pathway) were labelled with both GM1 and sphingosine. The results show that the catabolism of sphingo(glyco)lipids is dramatically enhanced in parallel with the increase of the autophagic pathway while at the same time their biosynthesis is reduced. The inhibition of autophagy in both undifferentiated cells and alpha i3-overexpressing cells restores sphingo(glyco)lipid metabolism, as normally expressed in differentiated cells, as well as in other mammalian cell types. We conclude that autophagy plays an important role in governing the metabolic fate of sphingo(glyco)lipids in HT-29 cells. Since autophagy regulates the N-linked glycoprotein metabolism in this cell line, our results corroborate the idea that glycolipid and glycoprotein metabolisms are controlled by similar mechanisms.

The structure of the DRB1*03 gene has been interpreted as the product of a gene conversion event involving a DRB3 gene as donor and resulting in the introduction of two short segments of the DRB3 sequence into the DRB1 locus. The serological counterpart of this double insertion is the TR81 specificity. Consequently, the TR81-specifying sequences can reside on either DRB1 or DRB3, or on both loci. Within each of the two sequence stretches a single nucleotide may be responsible for the generation of the TR81 alloantigen. Oligonucleotide probes corresponding to these stretches and to their allelic variants were constructed. They were used, under stringent hybridization conditions, to detect TR81-specifying sequences in the DNA of HLA-homozygous cell lines carrying different haplotypes of the DRw52 family. Prior to hybridization the DNA was amplified with either DRB1-specific or DRB3-specific primers. Using this approach it was possible to perform a "DNA typing" of the TR81-specifying sites separately on both the DRB1 locus and the DRB3 locus.