Quantitative genetics of complex traits: solutions for studying the genetic basis of variation in yeast

Recent advances in high-throughput techniques for DNA sequencing and phenotyping have greatly facilitated the identification of genetic variants underlying traits at a genomewide level. In this study, a large amount of yeast genetic resources and phenotypic data were collected for the study of natural genetic variation in yeast under different environment conditions. Quantitative trait locus (QTL) analysis and epistasis analysis have been applied to Saccharomyces cerevisiae on 6 groups of 1st generation bi-parental inter-cross segregants and 12th generation multiparental high resolution segregants. Using yeast as model organism, growth under stress conditions of a variety of conventional genotoxic agents was measured. Different QTLs were mapped to causative genes that are related to DNA repair and protein transport. In addition, by comparing the genes identified under 19 different agents, 14 frequently occurring genes producing effect on the growth of yeast, were further analysed. QTL output was clustered through a changepoint model for improving the selection of candidate genes in large gene sets. Furthermore, Temporal QTL analysis was applied to study the dynamic development of yeast growth under X-ray irradiation that expands the phenotype in the time dimension. By comparing the QTL in different time spans, genes that only exhibit effects for a certain period of time rather than continuously through, or at the end of, the experiment were found. One of the major industrial applications of yeast is brewing. In this project, whole genome sequencing analysis were performed on a highly diverse 12th generation de novo hybrid population. Variant calling was applied for these pool sequencing and identification of genetic variants. Pool QTL analysis was applied to compare the allele frequency difference of extreme pools under the same condition. Multiple QTL intervals responding to the brewing environment were identified. This provides useful genetic insights for brewing yeast breeding and improvement.</div

Beauty Matters: Social Preferences in a Three-Person Ultimatum Game

<div><p>Preference for beauty is human nature, as previous behavior studies have supported the notion of “beauty premium” in which attractive people were more easily to get promoted and receive higher salaries. In the present study, 29 males were recruited to participate in a three-person ultimatum game (UG) including a proposer, a responder and a powerless third player. Each subject, playing as the responder, had to decide whether to accept an offer from the allocator both for himself and a female third person. We aimed to elucidate how the facial attractiveness of the female subject affected the male subjects’ fairness and decision-making in social exchanges. Frontal feedback-related negativity (FRN) in response to four offers in an attractive-face condition revealed no significant differences between offers; however, when the companion was an unattractive female, an “unfair/fair” offer, which assigned a lower share to the responder and a fair share to the third player, elicited the largest FRN. Furthermore, when the third player was offered the smallest amount (“fair/unfair” offer), a larger FRN was generated in an attractive-face condition than unattractive-face condition. In the “unfair/fair” offer condition in which subjects received a smaller allocation than the third person, the beauty of their female counterparts attenuated subjects’ aversion to inequality, resulting in a less negative FRN in the frontal region and an increased acceptance ratio. However, the influence of the third player’s facial attractiveness only affected the early evaluation stage: late P300 was found to be immune to the “beauty premium”. Under the two face conditions, P300 was smallest following an “unfair/fair” offer, whereas the amplitudes in the other three offer conditions exhibited no significant differences. In addition, the differentiated neural features of processing facial attractiveness were also determined and indexed by four event-related potentials (ERP) components: N170, frontal N1, N2 and late positive potentials (LPPs).</p></div

Highly Selective Construction of Medium-Sized Lactams by Palladium-Catalyzed Intramolecular Hydroaminocarbonylation of Aminoalkynes

A novel palladium-catalyzed intramolecular hydroaminocarbonylation of aminoalkynes has been developed. This direct and operationally simple protocol provides a rapid and reliable approach to a diverse array of valuable seven- and eight-membered lactams with high chemoselectivity and regioselectivity. The high selectivity might be attributed to rational tuning the electronic nature of the amine moiety and the palladium catalyst, which enabled this transformation to proceed in the absence of acidic or any other additives under fairly mild reaction conditions. This method paves the way for the synthesis of medium-sized lactams

A single trial of the experimental procedure.

<p>Participants first saw either an attractive face or an unattractive face before the presentation of the offers. They made their choice by pressing the keypad and had unlimited time to make a decision. Screen then showed the final payoffs.</p

The ERP grand-average waveforms of P300 for four offers in the two face conditions at Pz and topographical maps for the four offer conditions.

<p>The time window for P300 was 400-600ms and the bar for the topographical map ranges from +6μv to -6μv.</p

The ERP grand-average waveforms of FRN at Fz in two face conditions.

<p>The time window for FRN was 290-370ms.</p

The reaction time and acceptance ratio of four offers in two face conditions.

<p>(*<i>p</i><0.05; **<i>p</i><0.01).</p

The comparison of the grand-average waveforms of FRN for the “unfair/fair” and “fair/unfair” offers at Fz and topographical maps.

<p>The time window for FRN was 290-370ms. The four maps on the right illustrate the topographical distribution of FRN with the time window “290-370ms” in the corresponding face condition. The bar chart depicts the comparison between the mean amplitude of the FRN for the “fair/unfair” and “unfair/fair” offers in two face conditions. The bar for the topographical map ranges from +3μv to -3μv. (*<i>p</i><0.05; **<i>p</i><0.01).</p

Case Study on Temperature-Accelerated Molecular Dynamics Simulation of Ligand Dissociation: Inducer Dissociation from the Lac Repressor Protein

We studied ligand dissociation from the inducer-binding domain of the Lac repressor protein using temperature-accelerated molecular dynamics (TAMD) simulations. With TAMD, ligand dissociation could be observed within relatively short simulation time. This allowed many dissociation trajectories to be sampled. Under the adiabatic approximation of TAMD, all but one degree of freedom of the system were sampled from usual canonical ensembles at room temperature. Thus, meaningful statistical analyses could be carried out on the trajectories. A systematic approach was proposed to analyze possible correlations between ligand dissociation and fluctuations of various protein conformational coordinates. These analyses employed relative entropies, allowing both linear and nonlinear correlations to be considered. Applying the simulation and analysis methods to the inducer binding domain of the Lac repressor protein, we found that ligand dissociation from this protein correlated mainly with fluctuations of side-chain conformations of a few residues that surround the binding pocket. In addition, the two binding sites of the dimeric protein were dynamically coupled: occupation of one site by an inducer molecule could significantly reduce or slow down conformational dynamics around the other binding pocket

Distribution of tweets posted at different time.

<p>(a) The hourly pattern. (b) The weakly pattern. In both (a) and (b), insets show the absolute fraction of each type of tweets at different time, from which it can be seen that the ambivalent tweets only occupy a small fraction in Weibo.</p