Anchor Points (anchor + point)

Distribution by Scientific Domains

Selected Abstracts

Crystal structure of HLA-A*2402 complexed with a telomerase peptide

Abstract HLA-A*2402 is the most commonly expressed HLA allele in oriental populations. It is also widely expressed in the Caucasian population, making it one of, if not the most abundant HLA,I types. In order to study its structure in terms of overall fold and peptide presentation, a soluble form of this HLA,I (,1, ,2, ,3 and ,2m domains) has been expressed, refolded and crystallized in complex with a cancer-related telomerase peptide (VYGFVRACL), and its structure has been solved to 2.8,Å resolution. The overall structure of HLA-A*2402 is virtually identical to other reported peptide-HLA,I structures. However, there are distinct features observable from this structure at the HLA,I peptide binding pockets. The size and depth of pocket,B makes it highly suitable for binding to large aromatic side chains, which explains the high prevalence of tyrosine at peptide position,2. Also, for HLA binding at peptide position,5, there is an additional anchor point, which allows the proximal amino acids to protrude out, providing a prominent feature for TCR interaction. Finally, pocket,F allows the anchor residue at position,9 to be bound unusually deeply within the HLA structure. [source]

Sperm ultrastructure of the spider crab Maja brachydactyla (Decapoda: Brachyura)

Carles G. Simeó
Abstract This study describes the morphology of the sperm cell of Maja brachydactyla, with emphasis on localizing actin and tubulin. The spermatozoon of M. brachydactyla is similar in appearance and organization to other brachyuran spermatozoa. The spermatozoon is a globular cell composed of a central acrosome, which is surrounded by a thin layer of cytoplasm and a cup-shaped nucleus with four radiating lateral arms. The acrosome is a subspheroidal vesicle composed of three concentric zones surrounded by a capsule. The acrosome is apically covered by an operculum. The perforatorium penetrates the center of the acrosome and has granular material partially composed of actin. The cytoplasm contains one centriole in the subacrosomal region. A cytoplasmic ring encircles the acrosome in the subapical region of the cell and contains the structures-organelles complex (SO-complex), which is composed of a membrane system, mitochondria with few cristae, and microtubules. In the nucleus, slightly condensed chromatin extends along the lateral arms, in which no microtubules have been observed. Chromatin fibers aggregate in certain areas and are often associated with the SO-complex. During the acrosomal reaction, the acrosome could provide support for the penetration of the sperm nucleus, the SO-complex could serve as an anchor point for chromatin, and the lateral arms could play an important role triggering the acrosomal reaction, while slightly decondensed chromatin may be necessary for the deformation of the nucleus. J. Morphol., 2010. © 2009 Wiley-Liss, Inc. [source]

Reliability and validity of a structured interview guide for the Hamilton Anxiety Rating Scale (SIGH-A)

M. Katherine Shear M.D.
Abstract The Hamilton Anxiety Rating Scale, a widely used clinical interview assessment tool, lacks instructions for administration and clear anchor points for the assignment of severity ratings. We developed a Structured Interview Guide for the Hamilton Anxiety Scale (SIGH-A) and report on a study comparing this version to the traditional form of this scale. Experienced interviewers from three Anxiety Disorders research sites conducted videotaped interviews using both traditional and structured instruments in 89 participants. A subset of the tapes was co-rated by all raters. Participants completed self-report symptom questionnaires. We observed high inter-rater and test-retest reliability using both formats. The structured format produced similar but consistently higher (+ 4.2) scores. Correlation with a self-report measure of overall anxiety was also high and virtually identical for the two versions. We conclude that in settings where extensive training is not practical, the structured scale is an acceptable alternative to the traditional Hamilton Anxiety instrument. Depression and Anxiety 13:166,178, 2001. © 2001 Wiley-Liss, Inc. [source]

Linkage map organization of expressed sequence tags and sequence tagged sites in the mosquito, Aedes aegypti

D. W. Severson
Abstract A composite genetic linkage map for the yellow fever mosquito Aedes aegypti was constructed based on restriction fragment length polymorphism (RFLP), single nucleotide polymorphism (SNP) and single strand conformation polymorphism (SSCP) markers. The map consists of 146 marker loci distributed across 205 cM, and includes several morphological mutant marker loci. Most of the genetic markers are derived from random cDNAs or Ae. aegypti genes of known function. A number of markers are derived from random genomic DNAs, including several cloned RAPD-PCR fragments, and also several cDNAs from Drosophila melanogaster. Most of the random cDNAs (80.2%) have high BlastX sequence identities to known genes, with the majority of matches to genes from D. melanogaster. Access to sequence data for all markers will facilitate their continued development for use in high-throughput SNP marker analyses and also provides additional physical anchor points for an anticipated genome sequencing effort. [source]

Synthesis of dendrimer,carbon nanotube conjugates

A. García
Abstract We describe the coupling between Carbon Nanotubes (CNTs) and a second-generation cyanophenyl-based dendrimer. The goal of our work is the synthesis of highly functionalized CNTs without provoking damage to the conjugated ,-system. One approach is the attachment of dendrimers with a high density of functional groups to the CNTs. These groups serve as anchor points for further reactions. With this aim, we have carried out a primary modification on CNTs by the use of 1,3 dipolar cycloaddition reaction. We have employed Single Wall Carbon Nanotubes (SWNTs) as well as Multi Wall Carbon Nanotubes (MWNTs) obtaining 238 ,mol and 511 ,mol of pyrrolidine groups per gram, respectively. The amount of amino groups introduced in the system was measured by the Kaiser test as well as thermogravimetric analyses. As a second step, dendrimer incorporation was performed by carbodiimide chemistry. Thermogravimetric Analysis, Raman Spectroscopy and Atomic Force Microscopy characterization techniques are reported for the characterization of the final CNT,dendrimer conjugate. The results show that the dendrimer has been attached covalently to the previously generated amine groups. Morphologically, the attached dendrimer with an estimated theoretical molecular length of 6.4 nm, generates a wrapping of 8 nm thick around the CNTs walls. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Kevlar and glass fiber treatment for thermoplastic composites by step polycondensation

H. Salehi-Mobarakeh
Nylon-6,6 was grafted at the surface of glass and plasma-treated Kevlar fibers for use in nylon,Kevlar thermoplastic composites. Hydroxyl and, in the case of Kevlar, amine end-groups occur at the fibre surface, either as defects or due to the plasma treatment. These were used as anchor points for nylon-6,6 step polycondensation. Fibers were subjected to successive dipping in adipoyl chloride/CH2Cl2 and aqueous hexamethylenediamine solutions in order to attach and grow high molecular weight polymer on the fiber surface. Grafted nylon was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, differential scanning calorimetry and thermogravimetry. It was shown that no backbiting occurred during the first stage of the grafting process and that the polymer quantity increased linearly with number of passes, up to ,50 passes for plasma-treated Kevlar and 100 for glass fibers, after which polymer quantity remained constant, within experimental error, which was attributed to the onset of termination reactions. POLYM. COMPOS., 28:278,286, 2007. © 2007 Society of Plastics Engineers [source]

Chicken microsatellite primers are not efficient markers for Japanese quail

M. Inoue-Murayama
Domestic fowl or chicken (Gallus gallus) and Japanese quail (Coturnix japonica) belong to the family Phasianidae. The exchange of marker information between chicken and quail is an important step towards the construction of a high-resolution comparative genetic map in Phasianidae, which includes several poultry species of agricultural importance. We tested chicken microsatellite markers to see if they would be suitable as genetic linkage markers in Japanese quail. Twenty-six per cent (31/120) of chicken primers amplified individual loci in Japanese quail and 65% (20/31) of the amplified loci were found to be polymorphic. Eleven of the polymorphic loci were excluded as uninformative because of the lack of amplification in some individuals or high frequency of nonspecific amplification. The sequence information of the remaining nine loci revealed six of them to contain microsatellites that were nearly identical with those of the orthologous regions in chicken. For these six loci, allele frequencies were estimated in 50 unrelated quails. Although the very few chicken markers that do work well in quail could be used as anchor points for a comparative mapping, most chicken markers are not useful for studies in quail. Therefore, more effort should be committed to developing quail-specific markers rather than attempting to adapt chicken markers for work in quail. [source]

Real-space protein-model completion: an inverse-kinematics approach

Henry Van Den Bedem
Rapid protein-structure determination relies greatly on software that can automatically build a protein model into an experimental electron-density map. In favorable circumstances, various software systems are capable of building over 90% of the final model. However, completeness falls off rapidly with the resolution of the diffraction data. Manual completion of these partial models is usually feasible, but is time-consuming and prone to subjective interpretation. Except for the N- and C-termini of the chain, the end points of each missing fragment are known from the initial model. Hence, fitting fragments reduces to an inverse-kinematics problem. A method has been developed that combines fast inverse-kinematics algorithms with a real-space torsion-angle refinement procedure in a two-stage approach to fit missing main-chain fragments into the electron density between two anchor points. The first stage samples a large number of closing conformations, guided by the electron density. These candidates are ranked according to density fit. In a subsequent refinement stage, optimization steps are projected onto a carefully chosen subspace of conformation space to preserve rigid geometry and closure. Experimental results show that fitted fragments are in excellent agreement with the final refined structure for lengths of up to 12,15 residues in areas of weak or ambiguous electron density, even at medium to low resolution. [source]