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The presence of a quaternary centre--a carbon with four other carbons bonded to it--in any given molecule can have a substantial chemical and biological impact. In many cases, it can enable otherwise challenging chemistry. For example, quaternary centres induce large rate enhancements in cyclization reactions--known as the Thorpe-Ingold effect--which has application in drug delivery for molecules with modest bioavailability.sup.1. Similarly, the addition of quaternary centres to a drug candidate can enhance both its activity and its metabolic stability.sup.2. When present in chiral ligands.sup.3, catalysts.sup.4 and auxiliaries.sup.5, quaternary centres can guide reactions toward both improved and unique regio-, stereo- and/or enantioselectivity. However, owing to their distinct steric congestion and conformational restriction, the formation of quaternary centres can be achieved reliably by only a few chemical transformations.sup.6,7. For particularly challenging cases--for example, the vicinal all-carbon.sup.8, oxa- and aza-quaternary centres.sup.9 in molecules such as azadirachtin.sup.10,11, scopadulcic acid A.sup.12,13 and acutumine.sup.14--the development of target-specific approaches as well as multiple functional-group and redox manipulations is often necessary. It is therefore desirable to establish alternative ways in which quaternary centres can positively affect and guide synthetic planning. Here we show that if a synthesis is designed such that each quaternary centre is deliberately leveraged to simplify the construction of the next--either through rate acceleration or blocking effects--then highly efficient, scalable and modular syntheses can result. This approach is illustrated using the conidiogenone family of terpenes as a representative case; however, this framework provides a distinct planning logic that is applicable to other targets of similar synthetic complexity that contain multiple quaternary centres. An approach in which quaternary centres are leveraged to improve synthetic planning can lead to shorter and optimized syntheses, demonstrated here on a series of polycyclic terpenes., Author(s): Pengfei Hu [sup.1] , Hyung Min Chi [sup.1] , Kenneth C. DeBacker [sup.1] , Xu Gong [sup.1] , Jonathan H. Keim [sup.1] , Ian Tingyung Hsu [sup.1] , Scott [...]

In poor nitrogen conditions, fission yeast cells mate, undergo meiosis and form spores that are resistant to deleterious environments. Natural isolates of Schizosaccharomyces pombe are homothallic. This allows them to naturally switch between the two h− and h+ mating types with a high frequency, thereby ensuring the presence of both mating partners in a population of cells. However, alteration of the mating type locus can abolish mating type switching or reduce it to a very low frequency. Such heterothallic strains have been isolated and are common in research laboratories due to the simplicity of their use for Mendelian genetics. In addition to the standard laboratory strains, a large collection of natural S. pombe isolates is now available, representing a powerful resource for investigating the genetic diversity and biology of fission yeast. However, most of these strains are homothallic, and only tedious or mutagenic strategies have been described to obtain heterothallic cells from a homothallic parent. Here, we describe a simple approach to generate heterothallic strains. It takes advantage of an alteration of the mating type locus that was previously identified in a mating type switching‐deficient strain and the CRISPR‐Cas9 editing tool, allowing for a one‐step engineering of heterothallic cells with high efficiency. Take‐away: Conventional methods for obtaining heterothallic fission yeast strains are inefficient.We implemented a streamlined genetic editing approach to engineer heterothallism.All fission yeast isolates reported in Jeffares et al. can be engineered.This method enhances the exploration of genetic diversity in wild fission yeast. [ABSTRACT FROM AUTHOR]

In this study, science faculty and educators collaboratively developed a plan to evaluate an interdisciplinary science curriculum and its administration policy. The science faculty were engaged in determining criteria for evaluation and interpreting data. The collaborative evaluation stressed graduate attributes in the affective domain and provided a dynamic for curriculum revision. Four cohorts of students voluntarily completed scales that measured their attitudes toward interdisciplinary study, course-taking patterns, and career choice. The results suggested that students' involvement and learning loadings were crucial to the effectiveness of the reform. Moreover, the traditional policy at Asian universities that requires entrants to declare a major should be changed, as most university entrants are not certain enough about their interests and abilities to make an appropriate decision about their major at such an early stage. (Contains 6 tables.)