Spatiotemporal consistency of neural responses to repeatedly presented video stimuli accounts for population preferences.

Population preferences for video advertisements vary across short video clips. What underlies these differences? Repeatedly watching a video clip may produce a consistent spatiotemporal pattern of neural activity that is dependent on the individual and the stimulus. Moreover, such consistency may be associated with the degree of engagement and memory of individual viewers. Since the population preferences are associated with the engagement and memory of the individual viewers, the consistency observed in a smaller group of viewers can be a predictor of population preferences. To test the hypothesis, we measured the degree of inter-trial consistency in participants' electroencephalographic (EEG) responses to repeatedly presented television commercials. We observed consistency in the neural activity patterns across repetitive views and found that the similarity in the spatiotemporal patterns of neural responses while viewing popular television commercials predicts population preferences obtained from a large audience. Moreover, a regression model that used two datasets, including two separate groups of participants viewing different stimulus sets, showed good predictive performance in a leave-one-out cross-validation. These findings suggest that universal spatiotemporal patterns in EEG responses can account for population-level human behaviours.

Multi-locus genotyping of bottom fermenting yeasts by single nucleotide polymorphisms indicative of brewing characteristics.

Yeast plays a capital role in brewing fermentation and has a direct impact on flavor and aroma. For the evaluation of competent brewing strains during quality control or development of novel strains it is standard practice to perform fermentation tests, which are costly and time-consuming. Here, we have categorized DNA markers which enable to distinguish and to screen brewing strains more efficiently than ever before. Sequence analysis at 289 loci in the genomes of six bottom fermenting Saccharomyces pastorianus strains revealed that 30 loci contained single nucleotide polymorphisms (SNPs). By determining the nucleotide sequences at the SNP-loci in 26 other S. pastorianus strains and 20 strains of the top fermenting yeast Saccharomyces cerevisiae, almost all these strains could be discriminated solely on the basis of the SNPs. By comparing the fermentative phenotypes of these strains we found that some DNA markers showed a strong association with brewing characteristics, such as the production of ethyl acetate and hydrogen sulphide (H2S). Therefore, the DNA markers we identified will facilitate quality control and the efficient development of brewing yeast strains.

Sugar induces death of the bottom fermenting yeast Saccharomyces pastorianus.

We confirmed that sugar-induced cell death (SICD) occurs in the bottom fermenting yeast Saccharomyces pastorianus under anaerobic conditions and that mitochondrial DNA is only partly required for SICD. Fermentation tests using different ratios of glucose and non-glucose nutrients demonstrated that SICD is influenced by the balance between these nutrients.

Expression profiling of the bottom fermenting yeast Saccharomyces pastorianus orthologous genes using oligonucleotide microarrays.

The bottom fermenting yeast Saccharomyces pastorianus is reported to have arisen as a natural hybrid of two yeast strains, S. cerevisiae and S. bayanus. The S. pastorianus genome includes S. cerevisiae-type (Sc-type) genes and orthologous lager-fermenting-yeast specific-type (Lg-type) genes derived from S. cerevisiae and S. bayanus, respectively. To gain insights into the physiological properties of S. pastorianus, we developed an in situ synthesized 60-mer oligonucleotide microarray for gene expression monitoring of these orthologous genes, consisting of approximately 6600 Sc-type genes and 3200 Lg-type genes. A comparison of the transcriptional profile of orthologous genes (e.g. Sc-type and Lg-type genes) in S. cerevisiae or S. bayanus demonstrated the feasibility of performing gene expression studies with this microarray. Genome-wide analysis of S. pastorianus with this microarray could clearly distinguish more than 67% of the expressed orthologous genes. Furthermore, it was shown that the gene expression of particular Lg-type genes differed from that of the orthologous Sc-type genes, suggesting that some Lg-type and Sc-type genes may have different functional roles. We conclude that the oligonucleotide microarray that we constructed is a powerful tool for the monitoring of gene expression of the orthologous genes of S. pastorianus.

Development of bottom-fermenting saccharomyces strains that produce high SO2 levels, using integrated metabolome and transcriptome analysis.

Sulfite plays an important role in beer flavor stability. Although breeding of bottom-fermenting Saccharomyces strains that produce high levels of SO(2) is desirable, it is complicated by the fact that undesirable H(2)S is produced as an intermediate in the same pathway. Here, we report the development of a high-level SO(2)-producing bottom-fermenting yeast strain by integrated metabolome and transcriptome analysis. This analysis revealed that O-acetylhomoserine (OAH) is the rate-limiting factor for the production of SO(2) and H(2)S. Appropriate genetic modifications were then introduced into a prototype strain to increase metabolic fluxes from aspartate to OAH and from sulfate to SO(2), resulting in high SO(2) and low H(2)S production. Spontaneous mutants of an industrial strain that were resistant to both methionine and threonine analogs were then analyzed for similar metabolic fluxes. One promising mutant produced much higher levels of SO(2) than the parent but produced parental levels of H(2)S.

Identification of bottom-fermenting yeast genes expressed during lager beer fermentation.

It has been proposed that bottom-fermenting yeast strains of Saccharomyces pastorianus possess at least two types of genomes. Sequences of genes of one genome [S. cerevisiae (Sc)-type] have been found to be highly homologous (more than 90% identity) to S. cerevisiae S288C sequences, while those of the other [Lager (Lg)-type] are less so. To identify and discriminate Lg-type from Sc-type genes expressed during lager beer fermentation, normalized cDNA libraries were constructed and analysed. From approximately 22 000 ESTs, 3892 Sc-type and 2695 Lg-type ORFs were identified. Expression patterns of Sc- and Lg-type genes did not correlate with particular cell functions in KEGG classification system. Moreover, 405 independent clones were isolated that have no significant homology with sequences in the S288C database, suggesting that they include the bottom-fermenting yeast-specific (BFY) genes. Most of BFY genes have significant homology with the S. bayanus genome.