Abstract and experiential thinking differentially account for anomalous perception of reality in people with or without schizophrenia

repetitive thinking is often increased in various psychopathological conditions. However, evidence for its possible contribution to psychotic symptoms relies only on correlational analysis and has not been experimentally tested within the psychotic continuum. This research aims to examine whether repetitive thinking about a negative past experience using concrete versus abstract processing might modify the reporting of anomalous sensory experiences. 89 patients with schizophrenia and 89 matched controls were asked to reflect on their most negative Self-Defining Memory during a thirty-minute period. By means of a written script, half of the participants were instructed to remember thoughts, feelings and sensations associated with the event in an abstract mode, while the other half followed an equivalent script but with concrete questions. After induced concrete-experiential thinking, both controls and patients significantly reduced self-reported anomalous reality perception. However, participants in the induced abstract-analytical thinking condition increased anomalous experience, especially sensory experience from an unexplained source. Multigroup path analyses showed that involvement in abstract-analytical thinking during the task significantly mediated the relationship between pre-test and post-test anomalous perception scores, but only in the patient group. These results suggest that abstract thinking contributes to distorted sensory experiences. In contrast, training in a concrete processing mode of past experiences may be a useful tool to reduce subjective anomalous perceptions.

A genomic approach for the identification and classification of genes involved in cell wall formation and its regulation in Saccharomyces cerevisiae

Using a hierarchical approach, 620 non-essential single-gene yeast deletants generated by EUROFAN I were systematically screened for cell-wall-related phenotypes. By analyzing for altered sensitivity to the presence of Calcofluor white or SDS in the growth medium, altered sensitivity to sonication, or abnormal morphology, 145 (23%) mutants showing at least one cell wall-related phenotype were selected. These were screened further to identify genes potentially involved in either the biosynthesis, remodeling or coupling of cell wall macromolecules or genes involved in the overall regulation of cell wall construction and to eliminate those genes with a more general, pleiotropic effect. Ninety percent of the mutants selected from the primary tests showed additional cell wall-related phenotypes. When extrapolated to the entire yeast genome, these data indicate that over 1200 genes may directly or indirectly affect cell wall formation and its regulation. Twenty-one mutants with altered levels of beta1,3-glucan synthase activity and five Calcofluor white-resistant mutants with altered levels of chitin synthase activities were found, indicating that the corresponding genes affect beta1,3-glucan or chitin synthesis. By selecting for increased levels of specific cell wall components in the growth medium, we identified 13 genes that are possibly implicated in different steps of cell wall assembly. Furthermore, 14 mutants showed a constitutive activation of the cell wall integrity pathway, suggesting that they participate in the modulation of the pathway either directly acting as signaling components or by triggering the Slt2-dependent compensatory mechanism. In conclusion, our screening approach represents a comprehensive functional analysis on a genomic scale of gene products involved in various aspects of fungal cell wall formation.

Cloning and characterization of the EXG1 gene from the yeast Yarrowia lipolytica

The YlEXG1 gene of Yarrowia lipolytica, encoding an exo-1, 3-beta-glucanase, was isolated by screening a genomic library with a DNA probe obtained by PCR amplification, using oligonucleotides designed according to conserved regions in the EXG1, EXG2 and SSG1 genes from Saccharomyces cerevisiae. YlEXG1 consists of a 1263 bp open reading frame encoding a protein of 421 amino acids with a calculated molecular weight of 48 209 Da. Northern blot analysis revealed a unique YlEXG1-specific transcript, 1.4 kb long. A putative pre(signal)-peptide of 15 amino acids is proposed at the N-terminal domain of the primary translation product. The deduced amino acid sequence shares a high degree of homology with exo-1, 3-beta-glucanases from other yeast species, including S. cerevisiae, Kluyveromyces lactis, Pichia angusta and Debaryomyces occidentalis. YlExg1p contains the invariant amino acid positions which have been shown to be important in the catalytic function of family 5 glycosyl hydrolases. Chromoblot analysis indicated that YlEXG1 is located on chromosome VI. Disruption of YlEXG1 did not result in a phenotype under laboratory conditions and did not prevent the yeast-hypha transition. The sequence data reported in this paper have been assigned EMBL Accession No. Z46872.

The nucleotide sequence of Saccharomyces cerevisiae chromosome XIV and its evolutionary implications

In 1992 we started assembling an ordered library of cosmid clones from chromosome XIV of the yeast Saccharomyces cerevisiae. At that time, only 49 genes were known to be located on this chromosome and we estimated that 80% to 90% of its genes were yet to be discovered. In 1993, a team of 20 European laboratories began the systematic sequence analysis of chromosome XIV. The completed and intensively checked final sequence of 784,328 base pairs was released in April, 1996. Substantial parts had been published before or had previously been made available on request. The sequence contained 419 known or presumptive protein-coding genes, including two pseudogenes and three retrotransposons, 14 tRNA genes, and three small nuclear RNA genes. For 116 (30%) protein-coding sequences, one or more structural homologues were identified elsewhere in the yeast genome. Half of them belong to duplicated groups of 6-14 loosely linked genes, in most cases with conserved gene order and orientation (relaxed interchromosomal synteny). We have considered the possible evolutionary origins of this unexpected feature of yeast genome organization.

The sequence of a 20.3 kb DNA fragment from the left arm of Saccharomyces cerevisiae chromosome IV contains the KIN28, MSS2, PHO2, POL3 and DUN1 genes, and six new open reading frames

We report the sequence of a 20 300 bp DNA fragment from the left arm of Saccharomyces cerevisiae chromosome IV. This segment contains 13 complete open reading frames (ORFs) and part of another ORF, altogether covering 84.2% of the entire sequence, five of which correspond to the previously characterized KIN28, MSS2, PHO2, POL3/CDC2 and DUN1 genes. One putative protein, D2358p, shares considerable homology with an O-sialoglycoprotein endopeptidase from Pasteurella haemolytica serotype A1. The putative product of D2325 contains the characteristic consensus motif of triacylglycerol lipases. D2320p and D2352p have a putative 'leucine-zipper' structure and a RNA-binding region Rnp-1 signature, respectively.

The sequence of a 21.3 kb DNA fragment from the left arm of yeast chromosome XIV reveals LEU4, MET4, POL1, RAS2, and six new open reading frames

The nucleotide sequence of a fragment of 21 308 bp from the left arm of Saccharomyces cerevisiae chromosome XIV has been determined. Analysis of the sequence revealed 13 open reading frames (ORFs) longer than 300 bp, four of which correspond to the previously identified genes LEU4, MET4, POL1 and RAS2. One putative protein, N2160, shares considerable homology (32% identity) with a hypothetical protein encoded by a gene located on chromosome XV as well as with human OCRL protein (36% identity), involved in Lowe's syndrome. N2185 contains ten predicted transmembrane segments and is similar to another putative protein (YKL146) from yeast.

Selective elongation of the oligosaccharide attached to the second potential glycosylation site of yeast exoglucanase: effects on the activity and properties of the enzyme

Three exoglucanases (Exgs), ExgIa, ExgIb and Exg325, are secreted by Saccharomyces cerevisiae cells. They share a common protein portion with two potential glycosylation sites (sequons) but differ in the amount of N-linked carbohydrate [Basco, R.D., Muñoz, M.D., Hernández, L.M., Váquez de Aldana, C. and Larriba, G. (1993) Yeast 9, 221-234]. ExgIb contains two short oligosaccharides attached to asparagines (Asn) 165 and 325 of the primary translation product [Hernández, L.M., Olivero, I., Alvarado, E. and Larriba, G. (1992) Biochemistry 31, 9823-9831]. Exg325 carries a single, short oligosaccharide bound to Asn325 whereas ExgIa has at least one large oligosaccharide, since it has not been produced by mutant mnn9. To address the question of the origin of ExgIa, both sequons were individually mutated by substituting Gln for Asn. An ExgIa-like isoenzyme was still secreted by mutant Exg165 but not by mutant Exg325. Additional studies on sequential deglycosylation of ExgIa with endo-beta-N-acetylglucosaminidase H (endo H), the susceptibility of both oligosaccharides to the endoglycosidase, and analysis of the presence of GlcNAc at both asparagine residues after total deglycosylation with endo H, indicated that ExgIa contained two oligosaccharides, a short one bound to Asn165 and a large one bound to Asn325, and, accordingly, originated from ExgIb. The elongation of the second oligosaccharide did not result in a higher stability towards thermal inactivation or unfolding, or in an increased resistance to proteases as compared with ExgIb; however, the affinity of the enzyme towards laminarin decreased by 50%. This site-specific elongation occurred in the oligosaccharide that was less susceptible to endo H, indicating that these properties are determined by different conformational constraints.

The complete sequence of a 15,820 bp segment of Saccharomyces cerevisiae chromosome XI contains the UBI2 and MPL1 genes and three new open reading frames

As part of the EEC yeast genome program, a fragment of 15,820 bp from the right arm of Saccharomyces cerevisiae chromosome XI has been sequenced. This fragment corresponds roughly to the centromere-distal half of cosmid pUKG046 and to a small fragment of cosmid pUKG096, which are located approximately 150 kb from the centromere. It contains four open reading frames (ORFs) which encode potential proteins of more than 100 amino acid residues, as well as the UBI2 gene which carries an intron and does not show up as an ORF in the sequence analysis programs. One of the putative proteins, YKR412, is very rich in serine and has significant homology at the carboxyl end to Nopp140 phosphoprotein. YKR413 has several predicted transmembrane domains. YKR15, which has been recently cloned as the MPL1 gene, encodes a polypeptide that shows homologies to myosin heavy chain and to the cytoskeleton protein Uso1.