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PubMed1984

Is meaning implicated in illusory conjunctions?

According to feature-integration theory, when attention is diverted from a display, features from different objects in that display may be wrongly recombined, giving rise to "illusory conjunctions" (Treisman & Schmidt, 1982). Two experiments are reported that examine the nature of these illusory conjunctions. In displays that contain color names and adjectives printed in colored ink, subjects made two kinds of interesting and previously unreported errors. Consider, for example, a display that included the word BROWN in red ink and the word HEAVY in green ink. Subjects would sometimes incorrectly report that the word RED or the ink color brown had appeared in the display (e.g., RED in green ink or HEAVY in brown ink). It appears that subjects extract semantic representations from input and are sometimes confused about whether a particular representation has been extracted from a word or a color patch. Contrary to feature-integration theory, these findings suggest that illusory conjunctions may occur with high-level codes as well as with perceptual features.

Color Perception↗

PubMed1999

An alarming lack of public awareness towards oral cancer.

OBJECTIVE: To determine public awareness and knowledge of oral cancer in Great Britain. DESIGN: The respondents were selected according to a systematic probability sample designed to be representative of all adults in Great Britain (GB). The overall design was similar to previous omnibus surveys carried out by National Opinion Poll (NOP). The survey was carried out in ten regions of GB in September 1995 and was commissioned by the Health Education Authority (HEA). SUBJECTS AND METHODS: A random sample of 1,894 members of the public over the age of 16 years were asked in face-to-face interviews their knowledge relating to cancer, with particular reference to oral cancer, its causes and those at high risk and general attitudes to cancer. RESULTS: Oral cancer was one of the least heard of cancers by the public with only 56% of the participants being aware, whereas 96% had heard of skin cancer, 97% lung cancer and 86% cervical cancer. There was a 76% awareness of the link between smoking and oral cancer but only 19% were aware of its association with alcohol misuse. Whereas 94% agreed that early detection can improve the treatment outcome, a disheartening 43% believed that whether a person developed a cancer or not was a matter of chance and therefore was unavoidable. CONCLUSIONS: This survey highlights a general lack of awareness among the public about mouth cancer and a lack of knowledge about its causation especially the excess risk associated with alcohol. RECOMMENDATIONS: There is a clear need to inform and educate the public in matters relating to the known risk factors associated with oral cancer. A media campaign informing the public about oral cancer is clearly required. The need for the reduction in the incidence of oral cancer should be included in 'Our healthier nation' targets. An overall health promotion strategy to reduce cancers should include oral cancer as a priority. In addition the European Code against Cancer which aims to improve prevention, the early detection of oral cancer and the necessity for fast track referral should be made more widely known. Recognition of oral cancer in local strategies for oral health should be encouraged.

Adolescent↗

PubMed1993

Differences between stutterers' and nonstutterers' short-term recall and recognition performance.

Longer rehearsal times presumably reduce the efficiency of rehearsal and, hence, of short-term recall. The present experiment examined the question as to whether the slower subvocalization rate of people who stutter is correlated with inferior short-term serial recall and recognition performance. Rate of overt articulation was taken as a measure of rehearsal time. Lists of four nonlexical CVC syllables were presented for short-term serial recall and for short-term recognition. Nineteen adults who stutter and 30 nonstutterers participated in the experiment. In the serial reproduction task the subjects who stuttered reproduced significantly fewer items correctly than did nonstutterers. Recognition performance was measured by nonparametric measures of sensitivity and bias as defined in signal detection theory. The stuttering subjects had a significantly lower sensitivity resulting primarily from a higher false alarm rate. Rate of overt articulation was significantly related to one measure of short-term recall but not to the sensitivity of recognition. These results were interpreted as suggesting that people who stutter have slower phonological encoding and rehearsal times, that they make less use of nonphonological forms of coding than do nonstutterers, and that within their phonological system, activation more easily spills over to similar items.

Adult↗

PubMed1987

The effect of orientation on visual and tactual braille recognition.

Five experiments are reported in which subjects matched tangible or visible braille characters against either visual or tangible arrays. In both modalities recognition was impaired when the characters were tilted, but visual performance was superior to that for touch. Touch may be more sensitive than vision to tilt, since very small deviations from the upright decreased recognition accuracy. Orientation influenced pattern recognition with and without prior information about orientation. Tilting patterns slowed down recognition for tactual-visual matching, but only when orientation was studied with repeated measures. The results are consistent with the hypothesis that it is difficult to code braille patterns tactually as global outline shapes.

Adult↗

PubMed1996

Genetic evidence that the RAG1 protein directly participates in V(D)J recombination through substrate recognition.

RAG1 protein is essential for the activation of V(D)J recombination in developing lymphocytes (V, variable; D, diversity; J, joining). However, it has not been determined whether its role involves substrate recognition and catalysis. A single amino acid substitution mutation in the RAG1 gene has now been identified that renders its activity sensitive to the sequence of the coding region abutting the heptamer site in the recombination signal sequence. These results strongly imply that RAG1 interacts directly with DNA.

Base Sequence↗

PubMed1997

Identification of protein coding regions in the human genome by quadratic discriminant analysis.

A new method for predicting internal coding exons in genomic DNA sequences has been developed. This method is based on a prediction algorithm that uses the quadratic discriminant function for multivariate statistical pattern recognition. Substantial improvements have been made (with only 9 discriminant variables) when compared with existing methods: HEXON [Solovyev, V. V., Salamov, A. A. & Lawrence, C. B. (1994) Nucleic Acids Res. 22, 5156-5163] (based on linear discriminant analysis) and GRAIL2 [Uberbacher, E. C. & Mural, R. J. (1991) Proc. Natl. Acad. Sci. USA 88, 11261-11265] (based on neural networks). A computer program called MZEF is freely available to the genome community and allows users to adjust prior probability and to output alternative overlapping exons.

Base Sequence↗

PubMed1999

Inactivation of brassinosteroid biological activity by a salicylate-inducible steroid sulfotransferase from Brassica napus.

Recent discoveries from brassinosteroid-deficient mutants led to the recognition that plants, like animals, use steroids to regulate their growth and development. We describe the characterization of one member of a Brassica napus sulfotransferase gene family coding for an enzyme that catalyzes the O-sulfonation of brassinosteroids and of mammalian estrogenic steroids. The enzyme is specific for the hydroxyl group at position 22 of brassinosteroids with a preference for 24-epicathasterone, an intermediate in the biosynthesis of 24-epibrassinolide. Enzymatic sulfonation of 24-epibrassinolide abolishes its biological activity in the bean second internode bioassay. This mechanism of hormone inactivation by sulfonation is similar to the modulation of estrogen biological activity observed in mammals. Furthermore, the expression of the B. napus steroid sulfotransferase genes was found to be induced by salicylic acid, a signal molecule in the plant defense response. This pattern of expression suggests that, in addition to an increased synthesis of proteins having antimicrobial properties, plants respond to pathogen infection by modulating steroid-dependent growth and developmental processes.

Amino Acid Sequence↗

PubMed1983

Analysis of pro-opiomelancortin gene structure and function.

Pro-opiomelanocortin (POMC) is the protein precursor to several physiologically distinct peptide hormones. The POMC gene is expressed in several distinct cell types and appears to be under differential regulation depending upon the cell location. The structure of the POMC gene in human, bovine, rat, and mouse is very similar, suggesting that this particular structure has functional significance. The gene is broken by intervening sequences into a 5' noncoding region, a signal sequence-coding region, and a peptide hormone-coding region. Middle-repetitive DNA sequences are present in both introns of the genes as well as the 5'-flanking regions in all species studied; this too suggests that this structural element has functional significance. The peptide hormone-coding sequences are well conserved among species, whereas the nonhormonal "spacer" sequences are poorly conserved. Differential regulation of the POMC gene appears to occur by the differential recognition of effector molecules. Although the studies are not complete, all available evidence suggests that there is only a single POMC gene which is express in mammalian tissues.

Animals↗

PubMed1992

Neglect and visual recognition.

B.Q., a right-handed woman who had suffered a stroke affecting the right parietal region, showed visuospatial neglect and problems in recognizing seen objects and faces. Investigation of her visual recognition problems revealed a striking inability to identify the left sides of chimaeric objects and faces. Often, B.Q. would deny that the stimulus was chimaeric at all, and she was remarkably poor (though above chance) at discriminating chimaeric from normal faces. Even when left-sided details had been accurately traced or described, they were often either ignored in reporting the identities of the constituent parts of a chimaeric or assimilated in some way to the information from the right side. Neglect of the left side was more pronounced for chimaerics which approximated an individual face or object. It occurred regardless of the chimaeric's position in B.Q.'s field of vision, and was found with brief (200 ms) presentations of stimuli confined to her (perimetrically intact) right visual field. When chimaeric faces were inverted, B.Q. continued to neglect the side of the chimaeric falling to her left, which implies that the neglect did not operate in entirely object-centered coordinates. However, left-sided information could be used if it was critical in determining the identity of an object or a face. We suggest that this could explain B.Q.'s lack of neglect of individual words, for which left-sided (initial) letters are often crucial to successful recognition. An account of her deficit is proposed, involving an interaction between moderately defective pick-up of left-sided information in an object-based coding system and preserved access to stored representations of familiar visual stimuli.

Attention↗

PubMed2002

Expressed sequence tags from roots and nodule primordia of Lotus japonicus infected with Mesorhizobium loti.

Messenger RNA from young Lotus japonicus roots carrying root nodule primordia appearing after inoculation with Mesorhizobium loti bacteria were used to construct a cDNA expression library. Single-pass sequencing employing colony-polymerase chain reaction (PCR) and analysis of PCR products established a total of 2,397 new expressed sequence tags (ESTs). We have putatively identified 1,236 known and 484 hypothetical proteins coded by the corresponding mRNAs. The remaining cDNAs are unknown (316) or redundant overlapping cDNAs (361). We hope that this batch of ESTs will assist in the recognition of plant genes involved during development of nitrogen-fixing root nodules.

DNA, Complementary↗

PubMed1980

Gene complementations to generate Ia antigens (Ia.23) on hybrid molecules.

Ia specificity 23 is a "combinatorial" antigen generated on a hybrid I region molecule, formed by the noncovalent binding of a 26,000- to 28,000-dalton beta polypeptide chain (Ae) coded by a gene in the I-A subregion with a 32,000- to 35,000-dalton alpha chain (E alpha) coded by a gene in the I-E subregion of the mouse H-2 gene complex. For expression of Ia.23, the Ae chain must be derived from the H-2d haplotype (I-Ad), while the E alpha can be provided by I-Ed, I-Ek, I-Ep, I-Er, I-Ev, and I-Ew3, but not I-Eb, I-Ef, I-Eq, I-Es, and I-Eu. With the exception of H-2u haplotype, all Ia.7 (I-E)-positive haplotypes can provide the permissive E alpha chain for generating Ia.23 by trans-complementation. In the H-2d haplotype, Ia.23 is generated by cis-complementation of Ad with Ed. Lymphocytes of F1 animals expressed two I-E subregion coded hybrid Ia specificities; one formed by cis-complementation and another by trans-complementation. It is postulated that such hybrid determinants are involved in the recognition and generation of immune response to antigens such as GL-Phe and cytochrome C where dual Ir gene control has been demonstrated. It is also suggested that there are two types of Ia specificities: (1) allotypic Ia specificities expressed on the alpha or beta chains (these could aid in the binding between the alpha and beta chains such as Ia.7); and (2) hybrid Ia specificities which are unique interaction determinants formed by the specific association of the alpha and beta chains (e.g., Ia.22,23). These interaction gene products may be involved in antigen recognition and presentation.

Animals↗

PubMed1969

Aminoacyl transfer ribonucleic acid synthetases from cell-free extract of Plasmodium berghei.

Aminoacyl transfer ribonucleic acid synthetases for leucine tyrosine, histidine, valine, proline, threonine, and lysine were obtainnned from cell-free extract of Plasmodium berghei. The leucyl-tRNA synthetase cane charge tRNA from liver or Escherichia coli with leucine-c(14), liver tRNA being a better substrate. The amount of aminoacylation increses linerly with respect to the quantity of tRNA added from either source and is dependent on the amount of enzyme added. The rate of aminoacylation is constant for 10 minutes and then decreases. It is enhanced by polyvinylsulfate. One-tenth millimoler pyrimethamine, hydroxystilbamidine, quinacrine, and acriflavine inhibited the formation of C(14)-valyl-tRNA. Species specificity between tRNA and its charging enzyme with respect to the recognition site is discussed.

Acridines↗

PubMed1987

Lysis gene t of T-even bacteriophages: evidence that colicins and bacteriophage genes have common ancestors.

The lysis gene t of the T-even-like bacteriophage K3 has been cloned and sequenced. The gene codes for a protein with a predicted molecular weight of 25,200. Expression of the complete lysis protein was impossible, but peptides complementing T4 amber mutants in t are described. No known lysis protein of other phages is homologous to protein T. Also, the Escherichia coli phospholipase A is different from protein T. CelB, the lysis protein of the colicin E2 operon, shows a similarity to protein T. Sequences of colicins A, E1, and E2 are related to gene 38 sequences, the gene preceding t and coding for the phage adhesin. A common origin for colicin genes and phage genes is discussed, and a protein region in colicins that is responsible for receptor recognition is predicted.

Amino Acid Sequence↗

PubMed1999

Contribution of virus-receptor interaction to distinct viral proliferation of neuropathogenic and nonneuropathogenic murine leukemia viruses in rat glial cells.

The efficiency of receptor-mediated entry of pseudotyped virus carrying the surface protein (SU) of clone A8, a neuropathogenic variant of Friend murine leukemia virus (FrMLV), to rat glial cell line F10 was 1 order of magnitude greater than that of pseudotyped virus carrying SU of nonneuropathogenic FrMLV clone 57. Introduction of the gene coding for ecotropic MLV receptor on F10 cells (F10-ecoR) into SIRC cells, which are naturally resistant to FrMLV infection, also revealed the difference in receptor recognition between the A8 and the 57 viruses. Our results show that the difference in receptor utilization between A8-SU and 57-SU only partially explains the 3-order-of-magnitude difference in proliferation between A8 and 57 viruses in F10 cells.

3T3 Cells↗

PubMed2004

Use of the event-related P300 potential in cochlear implant subjects for the study of strategy-dependent speech processing.

The present overview is a compilation of the results of several event-related potential (ERP) studies on auditory cortical processing, performed in the Evoked Potential Laboratory of the University Medical Centre of Nijmegen. To study speech perception performance in cochlear implant (CI) subjects, ERPs were obtained from subjects with poor and moderate performance. The present report describes the relationships between speech-coding strategies, the presentation of speech by the CI processor, the P300 potential as a measure of speech discrimination, time effects in the long term and speech recognition in relation to ERPs.

Brain Stem↗

PubMed1991

Interaction of a regulatory protein with a DNA target containing two overlapping binding sites.

The LexA repressor from Escherichia coli regulates the transcription of about 20 different genes upon binding to single or multiple operators. In this work we study the interaction of LexA with the control region of the caa gene (coding for the bacterial toxin colicin A) that contains two operators (O1 and O2) which overlap by at least 2 base pairs relevant for sequence specific DNA recognition. This arrangement raises the question of how the LexA molecules which bind to the central overlapping part of the two operators avoid steric clashes and further, of whether the interaction of LexA with the two operators is cooperative or not. To address these questions we have constructed two mutant operators (O1+O2- and O1-O2+) for which the two most strongly conserved base pairs in each of the external operator half-sites have been mutated. Using methylation interference with the complex formation of LexA with the wild-type and these two mutant operators we could show: 1) that the two mutant operators behave symmetrically in that the methylation of one crucial guanine base in both operator half-sites interferes strongly with complex formation, 2) but that in the wild-type operator (containing four functional operator half-sites) only the two external half-operators give rise to interference if this crucial guanine base is methylated, whereas methylation of the two equivalent guanine bases within the two central (overlapping) operator half-sites does not lead to interference with the formation of a complex where both operators are occupied simultaneously. These data suggest that the centrally bound LexA molecules adopt a somewhat different binding mode than those bound to the external half-operators in order to avoid steric clashes and/or to optimize protein-protein contacts which are likely to be at the origin of the binding cooperativity that we could demonstrate by quantitative DNase I footprinting and gel retardation experiments. While the methylation interference experiments revealed a non-equivalence for the binding of externally and centrally bound LexA molecules, both methylation protection and hydroxyl radical footprinting were unable to reveal this difference, suggesting that the difference between the two binding modes should be fairly subtle.

Bacterial Proteins↗

PubMed1986

Ontogeny of MHC-linked, T cell-mediated suppression is regulated by the T cell genotype.

Regulation of T cell effector functions by major histocompatibility complex (MHC) gene products has been extensively researched. Investigations in this area have established several important concepts of immunobiology. First, genes within the I-region of the MHC profoundly affect development of immune responses through their effects on cell-cell interactions. In the course of analyzing antigen-induced T cell activation, investigators identified specific Ir-genes by demonstrating that certain strains of mice were unable to develop immunity to defined antigens. It is now accepted that immune response defects in murine species are potentiated by cell surface molecules encoded within the I-subregion of the MHC, called Ia. Those molecules coded within the I-A subregion have the potential to be expressed by many different cell types. Second, induction of helper T cell effector function requires recognition of antigen in association with I-region encoded, cell surface molecules. For example, only a single structural combination of antigenic determinant and Ia molecule can deliver the inductive signal(s) to potential helper T cells. This fundamental aspect of helper T cell activation, now documented in numerous experimental systems, is referred to as MHC- or I-region restricted, antigen recognition. MHC-restriction is a characteristic of T cells mediating delayed-type hypersensitivity, help, and cytotoxicity. Third, several lines of evidence have established that T cell recognition of self-MHC molecules is a modifiable phenotype; conferred by a receptor having both variable and constant regions and not encoded by genes in the MHC. The development of both thymic grafted homozygous nu/nu mice and irradiation-induced bone marrow chimeras as experimental models resulted in a better understanding of the mechanism of MHC-restricted, antigen recognition. It was observed that expression of MHC gene products by the host is sufficient to select a new immune response phenotype for cellular interactions. The selection process takes place during T cell maturation, in the absence of antigen and under the dominant influence of the thymus, even though there is ample evidence for selective pressure in the extrathymic environment. For example, the self-MHC recognition repertoire of T cells in P----F1 chimeras undergoes an initial expansion which results in an F1 immune response phenotype. This expansion is followed by an apparent contraction back to the immune response phenotype of the parental donor. The contraction is time dependent and reflects accessory cell turnover in the irradiated host.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1984

Three regions of a yeast tRNALeu3 gene promote RNA polymerase III transcription.

A Saccharomyces cerevisiae tRNALeu3 gene has been dissected to identify sequences essential for recognition by the yeast RNA polymerase III transcription apparatus. Three putative promoter regions have been identified, one each in the 3'- and 5'-halves of the tRNA coding sequence, the A- and B-blocks, respectively, and one in the 5'-flanking region. DNA fragments derived from the intact gene and bearing the 5'-flanking region, the 5'-flanking region plus the A-block, the A- and B-blocks without the 5'-flanking region, the 5'-flanking region with the B-block, and the B-block only have been subcloned. Plasmids carrying these fragments were used as templates in a homologous in vitro transcription assay to determine the contributions of the various sequences to the template activity of the gene. No template-dependent transcription was seen when fragments with only the 5'-flanking region or B-block were tested. A very weak template-dependent transcript was observed from clones bearing the A- and B-block regions. Transcription of the fragment bearing the 5'-flanking sequence and A-block was considerably more efficient but reduced relative to the intact gene. The clone including the 5'-flanking region and 3'-half of the gene is transcribed by the yeast extract with an efficiency approaching that of the intact gene. Partial deletions were constructed in which the highly conserved 5'-flanking pentadecanucleotide sequence was replaced by vector DNA. Replacement of the sequence between positions -12 and -2 (relative to the tRNA coding sequence) decreased transcription efficiency 10-fold even though the A- and B-blocks were left intact. We conclude that this 5'-flanking region, in conjunction with either the A- or B-block sequence is sufficient to constitute a promoter for the yeast RNA polymerase III transcription apparatus.

Base Sequence↗