Background:The Cas9 RNA-guided endonuclease has been adapted for genome manipulation and regulation. Results: We have characterized target recognition and cleavage by Streptococcus thermophilus LMG18311 Cas9. Conclusion:The two nuclease domains of Cas9 select their cleavage sites by different mechanisms. Significance: These findings contribute to the molecular basis of Cas9-mediated DNA cleavage.

Problem definition: We consider a platform that charges commission rates and subscription fees to sellers and buyers for facilitating transactions but does not directly control the transaction prices, which are endogenously determined. Buyers and sellers are divided into types, and we represent the compatibility between different types using a bipartite network. Traders are heterogeneous in terms of their valuations, and different types have possibly different value distributions. Buyers may have additional value for trading with some seller types. The platform chooses commissions/subscriptions to maximize its revenues. Academic/practical relevance: Two salient features of most online platforms are that they do not dictate the transaction prices, and they use commissions/subscriptions for extracting revenues. We shed light on how these commissions/subscriptions should be set in networked markets. Methodology: Using tools from convex optimization and combinatorial optimization, we obtain tractable methods for computing the optimal commissions/subscriptions and provide insights into the platform’s revenues, buyer/seller surplus, and welfare. Results: We provide a tractable convex optimization formulation to obtain the revenue-maximizing commissions/subscriptions, and establish that, typically, different types should be charged different commissions/subscriptions depending on their network positions. We establish that the latter result holds even when the traders on each side have identical value distributions, and in this setting we provide lower and upper bounds on the platform’s revenues in terms of the supply-demand imbalance across the network. Motivated by simpler schemes used in practice, we show that the revenue loss can be unbounded when all traders on the same side are charged the same commissions/subscriptions, and bound the revenue loss in terms of the supply-demand imbalance across the network. Charging only buyers or only sellers leads to at least half of the optimal revenues, when different types on the same side can be charged differently. Managerial implications: Our results highlight the suboptimality of commonly used payment schemes and showcase the importance of accounting for the compatibility between different user types.

Twelve rice cultivars with differential resistance to rice blast disease (Magnaporthe oryzae (Hebert) Barr), including Tetep (R), IR36 (MR) and Lijiangxituanhegu (HS), and nine locally planted rice cultivars in Jiangxi helped establish an identification method for rice resistance to neck blast. We describe a new technique of dropping a spore suspension on the panicle segment in vitro (DSSPS). This technique involved rice panicles that were initially 0.5–2 cm in length and then cut into a 7‐ to 8‐cm segment (i.e. an upper node of 1 cm and a lower node of 6–7 cm). The segment was placed into a Petri dish with a stack of sterile water saturated filter paper. The suspension (4 μl 1 × 105spores/ml) was placed at each of three locations on the segment (with an approximate interval of 3 cm). Disease severity was then assessed according to a 0–9 scale after incubating for 9 days with a 12 h/12 h (light/day cycle) at 28°C. Choosing a suitable developmental stage of the rice panicle and blast strains was a key to evaluate resistance accurately. DSSPS is a simple and accurate method of identifying rice resistance to neck blast as compared to injecting the spore suspension into the rice panicle in vivo and resistance identification in natural nurseries. It is stressed that at least 20 single‐spore strains are needed to accurately assess rice resistance to neck blast. We tested 1005 rice cultivars for neck blast resistance in Jiangxi province during 2010–2015, which showed an accuracy of 85.77% by DSSPS as compared with natural nursery data.