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At least 343 records · Page 19Linked to original sources
PubMed2005

Looking into flowering time in almond (Prunus dulcis (Mill) D. A. Webb): the candidate gene approach.

Blooming time is one of the most important agronomic traits in almond. Biochemical and molecular events underlying flowering regulation must be understood before methods to stimulate late flowering can be developed. Attempts to elucidate the genetic control of this process have led to the identification of a major gene (Lb) and quantitative trait loci (QTLs) linked to observed phenotypic differences, but although this gene and these QTLs have been placed on the Prunus reference genetic map, their sequences and specific functions remain unknown. The aim of our investigation was to associate these loci with known genes using a candidate gene approach. Two almond cDNAs and eight Prunus expressed sequence tags were selected as candidate genes (CGs) since their sequences were highly identical to those of flowering regulatory genes characterized in other species. The CGs were amplified from both parental lines of the mapping population using specific primers. Sequence comparison revealed DNA polymorphisms between the parental lines, mainly of the single nucleotide type. Polymorphisms were used to develop co-dominant cleaved amplified polymorphic sequence markers or length polymorphisms based on insertion/deletion events for mapping the candidate genes on the Prunus reference map. Ten candidate genes were assigned to six linkage groups in the Prunus genome. The positions of two of these were compatible with the regions where two QTLs for blooming time were detected. One additional candidate was localized close to the position of the Evergrowing gene, which determines a non-deciduous behaviour in peach.

Chromosome Mapping↗
PubMedDate not supplied

Emulation of somatosensory evoked potential (SEP) components with the 3-shell head model and the problem of 'ghost potential fields' when using an average reference in brain mapping.

In brain topographic mapping, the putative location and orientation in the head space of neural generators are currently inferred from the features of negative and positive scalp potential fields. This procedure requires the use of a fairly neutral reference. The frequently advocated average reference creates problems because its effect is not merely to change a (steady) zero reference level, but to dynamically zero-center all scalp potentials at each latency. Ghost potential fields are thus created at the latencies for which the integral of scalp recorded potentials differs from zero. These distortions of brain mapping have been analyzed with a true 3-shell head model in conjunction with the emulation of SEP components. In the head model, surface potential fields generated by dipoles or dipole sheets of various depths and orientations were computed either over the north hemisphere, so as to emulate scalp recorded SEP components, or over the entire equivalent head sphere. The spurious effects of the average reference are shown to occur because it is computed from a limited number of (scalp) electrodes which fail to survey the bottom half of the head.

Adult↗
PubMed1994

Integrated human genome-wide maps constructed using the CEPH reference panel.

High resolution linkage maps have proven to be invaluable tools in genetic investigations. We have assembled a collection of genetic maps constructed from primary data collected from investigators performing genotyping using the Centre Etude Polymorphism Humain (CEPH) reference pedigree panel. These maps were constructed using a rigorous, semi-automated map construction algorithm that evaluates the integrity of the maps during construction. Two classes of maps were produced: a high confidence "skeletal" set composed of 544 PCR based markers, and a more highly annotated "framework" set containing maps of 1,123 markers. Genetic map locations within the framework maps are provided for an additional 1,758 loci without statistically unique interval assignments.

Algorithms↗
PubMed1998

Use of a Phase Reference for Field Mapping with Amplitude Images at Low Field

We present a method to obtain MRI amplitude images that can picture the magnetic field due to arbitrary shaped magnetized objects. The method employees the gradient recalled echo sequence and two sets of data obtained in separate experiments, one of which provides a phase reference image making it possible to eliminate the effect of the B0 field inhomogeneities. The final magnitude images have a good signal-to-noise even at low fields, and provide qualitative as well as quantitative information about the magnetic field produced by the ferromagnetic object. As an example the method is applied to study the field produced by a small metal piece in a 500-G scanner, and the experimental results are compared with numerical simulations. Copyright 1998 Academic Press.

Journal Article↗
PubMed2000

[Determinants of sketch-map orientation: an examination into the adoption of egocentric and conventional systems of reference to sketch-map drawing].

This study examined the determinants of adults' sketch-map orientation in terms of adoption of Egocentric and Conventional Systems of Reference (ESR and CSR) proposed by Sholl and Egeth (1980). If an ESR adoption in sketch-map drawing depends on a tuning activity of 'orienting schemata' (Sholl, 1987), subjects are expected to comprehend their own body direction accurately at the current position. To test this hypothesis, subjects were asked to judge the direction to the library entrance relative to their body direction at the current position. Subjects were asked to judge the direction to the north, to confirm that those who adopted CSR in sketch-map drawing regard the top of the sketch-map as north. In addition, whether the frequency of ESR adoption increases by telling subjects to draw the current position first, or not was examined. Results indicated a significant increase in ESR adoption. Subjects who adopted ESR performed well in judging the direction to the library entrance. On the other hand, subjects who adopted CSR poorly performed in judging the direction to the north.

Adult↗
PubMed1999

Multipoint linkage disequilibrium mapping with particular reference to the African-American population.

A new approach to scanning the genome is presented to detect linkage disequilibrium caused specifically by population admixture. In contrast to current linkage genome scanning methods to find causal genes for complex diseases, this new method should be powerful to find genes for multilocus traits, particularly those genes that lead to the highest population attributable risk. Such a scan using the African-American population is generally feasible for mapping common diseases. A conservative threshold is also provided for such association mapping.

Alleles↗
PubMed1999

Application of AFLP markers to genome mapping in poultry.

The amplified fragment length polymorphism (AFLP) technique has been used to enhance marker density in the East Lansing reference chicken genome map, using a backcross family derived from a Red Jungle Fowl by White Leghorn mating with White Leghorn as the recurrent parent. To date, 204 AFLP markers have been added, expanding overall map coverage by about 25%. To the limits of our resolution, AFLP markers are distributed relatively evenly across the EL reference map. AFLP are about 60% as frequent in a cross within White Leghorns (line 7(2) x 6(3)) in comparison to the more divergent reference map population. Based on apparent identity of size, about 40% of the 7(2) x 6(3) cross AFLP fragments were also polymorphic in the reference map cross. Primer pairs in which one primer contains 3' extensions of three selective nucleotides and the other has two selective nucleotides successfully generated AFLP from chicken DNA, but such pairs appeared to amplify only a subset of those fragments to which they have an exact sequence match. Three different restriction enzymes with 4 bp recognition sites (TaqI, HinP1I and MspI) were found to work well with EcoRI as the rarer of the two AFLP restriction enzymes used, with HinP1I being the most effective of the three. AFLP markers are likely to provide an economical method with which to enhance framework linkage maps of chicken and probably other avian genomes.

Animals↗
PubMed2005

Gravitational influences on reference frames for mapping somatic stimuli in brain-damaged patients.

Previous studies have shown that the manipulation of body position in space can modulate the manifestations of visual neglect. Here, we investigated in right brain-damaged patients (RBD) the possible influence of gravitational inputs on the capability to detect tactile stimuli delivered to hands positioned in ipsilesional or contralesional space. RBD patients (with or without impairments in detecting contralesional stimuli under single and double stimulation conditions) and healthy control subjects were tested in a tactile detection task in which gravitational (upright vs. supine) and hand position (anatomical vs. crossed) variables were orthogonally varied. The postural manipulation of the entire body turned out to influence the degree of tactile detection. In particular, RBD patients with tactile deficits detected a significantly higher number of left-sided stimuli in the supine posture than in the upright posture. Moreover, crossing of hands improved the ability of RBD patients with tactile deficits in detecting stimuli delivered to their left contralesional hand. The beneficial effect of lying supine was independent of the spatial position of the hands, thus suggesting that the improvement of performance dependent upon entire-body posture and that dependent upon crossing hands may rely upon separate mechanisms.

Aged↗
PubMedDate not supplied

Inadequacy of the average reference for the topographic mapping of focal enhancements of brain potentials.

The main reason for doing topographic mapping of EEG or evoked potentials is to assess regional changes in brain potentials. The use of an average reference is shown to have perverse effects in this relation, namely because it imposes on the recorded data a zero-centering effect which can reduce, eliminate or even reverse the focal changes of bit-mapped brain potentials. Concurrent studies on a true 3-shell head model suggest that such distortions of human EEG data occur because the average reference is computed from a set of (scalp) recording electrodes which do not survey the bottom half of the head volume so that the integral of scalp-recorded potentials frequently differs from zero. The results also raise the question whether the actual incidence of radial or near-radial (versus tangential) generators has been underestimated in the published data using average reference mapping.

Adult↗
PubMed1998

Proteins of rat serum: I. Establishing a reference two-dimensional electrophoresis map by immunodetection and microbore high performance liquid chromatography-electrospray mass spectrometry.

In the present investigation, we have identified 56 major spots, or spot rows, corresponding to 22 proteins, in the 2-DE pattern of adult male rats. This was done mainly by applying two complementary techniques, namely immunoblotting and high performance liquid chromatography-mass spectrometry (HPLC-MS) peptide mapping. Glycoproteins were characterized by affinity blotting with six lectins. We have also detailed how rat serum differs from human serum in two main respects: (i) relative abundance of individual proteins, which amounts in some cases to a complete absence in either sample, and (ii) varying molecular parameters for homologous proteins. It was thus possible to establish a first-generation reference map of rat serum proteins, which can be accessed through http://weber.u.washington.edu/ruedilab/aebersold++ +.html. We hope the present database will be a useful reference for the evaluation of changes in serum protein distribution in the course of pharmacological and toxicological studies. The recognition of species-specific proteins appears of special relevance in this respect.

Animals↗
PubMed2001

Human primary auditory cortex: cytoarchitectonic subdivisions and mapping into a spatial reference system.

The transverse temporal gyrus of Heschl contains the human auditory cortex. Several schematic maps of the cytoarchitectonic correlate of this functional entity are available, but they present partly conflicting data (number and position of borders of the primary auditory areas) and they do not enable reliable comparisons with functional imaging data in a common spatial reference system. In order to provide a 3-D data set of the precise position and extent of the human primary auditory cortex, its putative subdivisions, and its topographical intersubject variability, we performed a quantitative cytoarchitectonic analysis of 10 brains using a recently established technique for observer-independent definition of areal borders. Three areas, Te1.1, Te1.0, and Te1.2, with a well-developed layer IV, which represent the primary auditory cortex (Brodmann area 41), can be identified along the mediolateral axis of the Heschl gyrus. The cell density was significantly higher in Te1.1 compared to Te1.2 in the left but not in the right hemisphere. The cytoarchitectonically defined areal borders of the primary auditory cortex do not consistently match macroanatomic landmarks like gyral and sulcal borders. The three primary auditory areas of each postmortem brain were mapped to a spatial reference system which is based on a brain registered by in vivo magnetic resonance imaging. The integration of a sample of postmortem brains in a spatial reference system allows one to estimate the spatial variability of each cytoarchitectonically defined region with respect to this reference system. In future, the transfer of in vivo structural and functional data into the same spatial reference system will enable accurate comparisons of cytoarchitectonic maps of the primary auditory cortex with activation centers as established with functional imaging procedures.

Adult↗
PubMed1989

Biochemical effects of Navelbine on tubulin and associated proteins.

Navelbine (NVB) or 5' nor-anhydro-vinblastine was shown to present a broader antitumor activity and to induce fewer side effects than vinblastine (VBL) or vincristine (VCR). The possible mechanisms of these differences were analyzed with in vitro methods. At substoichiometric concentrations, the three drugs inhibit microtubule assembly. NVB, in comparison with VCR and VBL, is shown to have a lower inhibitory effect. At stoichiometric concentrations, the three drugs are able to induce tubulin aggregation into spirals and paracrystals. This process involves a microtubule-associated protein (MAPs) family referred to as Tau and is inhibited by another MAPs family referred to as MAP2. However, dramatic quantitative and qualitative differences are observed between NVB and VLB or VCR in TAU-induced aggregation of tubulin. The rate and extent of NVB-induced tubulin aggregation is much lower. With NVB, only certain TAU isoforms are able to induce paracrystals, while all TAU isoforms may contribute to VCR-induced or VBL-induced paracrystals. The TAU isoforms that are not able to induce crystallization with NVB, at least in a certain range of concentrations, are probably involved in mitotic microtubules--the hypothetical antitumoral target of vinca alkaloids (VAS). The present work shows for the first time that an anticancer drug is able to discriminate between the various types of microtubules. A next step will be to investigate whether this property is limited to a modulating effect of the various TAU isoforms on the affinity of VAS for tubulin. These biochemical investigations will be extended to tubulins extracted from tumor cell lines in order to further discriminate NVB from the other VAS.

Animals↗
PubMed2004

Testing the ISO nursing reference terminology model for mapping.

PURPOSE: The ISO IS 18104 is intended for helping the nursing profession to integrate their terminologies into computer systems and into larger health care reference terminologies. One purpose of the standard is to map between different terminologies. METHOD: This mapping was tested, using three terminologies that are relevant for nursing in the Netherlands. Concepts and terms where selected, and their equivalence was determined by experts, and next these were dissected. RESULTS: The dissection revealed that several concepts can easily be interchanged among the three example terminologies, while others cannot, or only for specific purposes. CONCLUSIONS: The ISO IS 18104 fulfills this purpose very well and can be considered the gold standard for mapping of nursing terminologies.

Netherlands↗
PubMed1997

Amplitude changes of tibial nerve cortical somatosensory evoked potentials when the ipsilateral or contralateral ear is used as reference.

We performed topographical mapping of somatosensory evoked potentials (SEPs) to the posterior tibial nerve using earlobe references both ipsilateral and contralateral to the stimulation side. The voltage of the frontal contralateral N37 and P50 components was enhanced, while the voltage of the parietal ipsilateral P37 and N50 components was reduced when the contralateral earlobe was substituted by the ipsilateral earlobe reference. Maps of the same data documented concomitant changes in negative and positive potential fields, showing an expansion of the pre-Rolandic N37 toward the centrotemporal contralateral regions, and a tendency of the parietal ipsilateral P37, N50 components to be more focally distributed at the vertex. SEPs recorded at each earlobe (Cv6 reference) provided an explanation of these results: The contralateral earlobe detected a negative potential corresponding to the N37 potential recorded over the scalp, followed by a P50 potential that attenuated the contralateral responses and enhanced the ipsilateral ones. The ipsilateral earlobe had no significant effects on scalp SEPs, since it detected only a large N33 negativity. Current source density (CSD) maps were, of course, not influenced by the ear used as reference. Our results suggest that the ipsilateral ear reference is better than the contralateral one for recording "genuine" cortical SEPs. Therefore, it can be recommended in the clinical domain for mapping studies of lower-limb cortical SEPs.

Adult↗
PubMedDate not supplied

Intracerebral dipole sources of EEG FFT power maps.

The described method opens a way to compute intracerebral source localizations of ongoing EEG activity. A sine-cosine diagram of the Fourier-transformed data is constructed for each frequency point, forming a "FFT constellation" of entries. Into the FFT constellation of each diagram, a straight line is fitted which produces the least squared deviation sum between the original entry positions and their orthogonal projections onto that line. The map landscape described by the voltages between the projected positions ("FFT approximation") is the least error compromise landscape of all possible landscapes during the paradigmatic cycle of the given FFT frequency. The map thus constructed can be used in the usual dipole source localization procedures. There is one for each FFT frequency point. The squared forward solution of the fitted dipole source and the squared FFT approximation map are "power maps" which are very similar to the original power map. For an average-reference power map with two peaks, the source tends to lie between the peaks; a power map with one peak might show closely neighboring maximal and minimal potential values in the FFT approximation, indicative of a tangential source close to the surface.

Brain↗
PubMed2005

A composite linkage map from two crosses for the species complex Picea mariana x Picea rubens and analysis of synteny with other Pinaceae.

Four individual linkage maps were constructed from two crosses for the species complex Picea mariana (Mill.) B.S.P. x Picea rubens Sarg in order to integrate their information into a composite map and to compare with other Pinaceae. For all individual linkage maps, 12 major linkage groups were recovered with 306 markers per map on average. Before building the composite linkage map, the common male parent between the two crosses made it possible to construct a reference linkage map to validate the relative position of homologous markers. The final composite map had a length of 2,319 cM (Haldane) and contained a total of 1,124 positioned markers, including 1,014 AFLPs, 3 RAPDs, 53 SSRs, and 54 ESTPs, assembled into 12 major linkage groups. Marker density of the composite map was statistically homogenous and was much higher (one marker every 2.1 cM) than that of the individual linkage maps (one marker every 5.7 to 7.1 cM). Synteny was well conserved between individual, reference, and composite linkage maps and 94% of homologous markers were colinear between the reference and composite maps. The combined information from the two crosses increased by about 24% the number of anchor markers compared to the information from any single cross. With a total number of 107 anchor markers (SSRs and ESTPs), the composite linkage map is a useful starting point for large-scale genome comparisons at the intergeneric level in the Pinaceae. Comparisons of this map with those in Pinus and Pseudotsuga allowed the identification of one breakdown in synteny where one linkage group homologous to both Picea and Pinus corresponded to two linkage groups in Pseudotsuga. Implications for the evolution of the Pinaceae genome are discussed.

Chromosome Mapping↗
PubMed2002

Using the new dietary reference intakes to assess diets: a map to the maze.

New Dietary Reference Intakes (DRIs) are being set by the Institute of Medicine, and represent a new way of defining nutrient intake recommendations. For the first time, the recommendations for the United States and Canada allow the calculation of the probability of adequacy for an individual, and the prevalence of inadequacy for a population. In addition, possible excessive consumption of many nutrients can be evaluated. The goal of this review is to provide a practical guide to the proper uses of the new DRIs when assessing intakes.

Child↗