Highly efficient CRISPR-SaKKH tools for plant multiplex cytosine base editing

Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9 ortholog from Staphylococcus aureus(SaCas9), is important in genome editing because it can edit sites with HHHAAT protospacer adjacent motif(PAM) that the canonical Streptococcus pyogenes Cas9(SpCas9) or its variants(e.g. xCas9, Cas9-NG) cannot. However, several technical parameters of SaKKH involved base editors have not been well defined and this uncertainty limits their application. We developed an effective multiplex cytosine base editor(SaKKHn-pBE) and showed that it recognized NNARRT, NNCRRT, NNGRGT, and NNTRGT PAMs. Based on 27 targets tested, we defined technical parameters of SaKKHn-pBE including the editing window, the preferred sequence context, and the mutation type. The editing efficiency was further improved by modification of the SaKKH sgRNA. These advances can be applied in future research and molecular breeding in rice and other plants.

High performance of low voltage controlled ring oscillator with reverse body bias technology

In complementary metal oxide semiconductor （CMOS） nanoscalc technology, power dissipation is becoming important metric. In this work low leakage voltage controlled ring oscillator circuit system was proposed for critical communication systems with high oscillation frequency. An ideal approach has been presented with substrate biasing technique for reduction of power consumption. The simulation have been completed using cadence virtuoso 45 nm standard CMOS technology at room temperature 27~C with supply voltage Vc^d = 0.7 V. The simulation results suggest that voltage controlled ring oscillator has characterized with efficient low power voltage controlled oscillator （VCO） in term of minimum leakage power （1.23 nW） and maximum oscilla- tion frequency （4.76 GHz） with joint positive channel metal oxide semiconductor and negative channel metal oxide semiconductor （PMOS and NMOS） reverse sub- strate bias technique. PMOS, NMOS and joint reverse body bias techniques have been compared in the presented work.