Development and Optimization of CRISPR Prime Editing System in Photoautotrophic Cells.

Prime editor (PE), a versatile editor that allows the insertion and deletion of arbitrary sequences, and all 12-point mutations without double-strand breaks (DSB) and a donor template, dramatically enhances research capabilities. PE combines nickase Cas9(H840A) and reverse transcriptase (RT), along with prime editing guide RNA (pegRNA). It has been reported in several plant species, but a weak editing efficiency has led to a decrease in applications. This study reports an optimized-prime editor (O-PE) for endogenous gene editing in Arabidopsis thaliana cells, with an average 1.15% editing efficiency, which is 16.4-fold higher than previously reported. Meanwhile, we observed an increase in indels when testing alternative reverse transcriptase and found out that nCas9(H840A) fused to non-functional reverse transcriptase was responsible for the increase. This work develops an efficient prime editor for plant cells and provides a blueprint for applying PE in other photoautotrophic cells, such as microalgae, that have a high industrial value.

Healthcare utilization and total costs of care among patients with advanced metastatic gastric and esophageal cancer.

Aim: Study first-line (1L) treatment patterns and economic outcomes among patients with advanced metastatic gastric cancer (GC) and esophageal cancer (EC). Materials & methods: Newly diagnosed patients with systemic GC and EC treatments were identified between 1 January 2011 and 31 July 2017; costs were presented as per patient per month (PPPM) basis. Results: Study included 392 GC and 436 EC patients. Most frequently used 1L regimens were: 5-fluorouracil (5-FU) + oxaliplatin (22.5%) and epirubicin + cisplatin + 5-FU (ECF)/ECF modifications (21.9%) in patients with GC; and carboplatin + paclitaxel (29.6%) and 5-FU + oxaliplatin (11.5%) in EC patients. Mean all-cause costs were US$16,242 PPPM for GC, and $18,384 PPPM for EC during 1L treatment. Conclusion: GC and EC were resource intensive and costly. High costs and short treatment durations underscored a gap in care in 1L treatment.

CRISPR base editing and prime editing: DSB and template-free editing systems for bacteria and plants.

CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR associated) has been extensively exploited as a genetic tool for genome editing. The RNA guided Cas nucleases generate DNA double-strand break (DSB), triggering cellular repair systems mainly Non-homologous end-joining (NHEJ, imprecise repair) or Homology-directed repair (HDR, precise repair). However, DSB typically leads to unexpected DNA changes and lethality in some organisms. The establishment of bacteria and plants into major bio-production platforms require efficient and precise editing tools. Hence, in this review, we focus on the non-DSB and template-free genome editing, i.e., base editing (BE) and prime editing (PE) in bacteria and plants. We first highlight the development of base and prime editors and summarize their studies in bacteria and plants. We then discuss current and future applications of BE/PE in synthetic biology, crop improvement, evolutionary engineering, and metabolic engineering. Lastly, we critically consider the challenges and prospects of BE/PE in PAM specificity, editing efficiency, off-targeting, sequence specification, and editing window.

An intracellular membrane protein GEP1 regulates xanthurenic acid induced gametogenesis of malaria parasites.

Gametocytes differentiation to gametes (gametogenesis) within mosquitos is essential for malaria parasite transmission. Both reduction in temperature and mosquito-derived XA or elevated pH are required for triggering cGMP/PKG dependent gametogenesis. However, the parasite molecule for sensing or transducing these environmental signals to initiate gametogenesis remains unknown. Here we perform a CRISPR/Cas9-based functional screening of 59 membrane proteins expressed in the gametocytes of Plasmodium yoelii and identify that GEP1 is required for XA-stimulated gametogenesis. GEP1 disruption abolishes XA-stimulated cGMP synthesis and the subsequent signaling and cellular events, such as Ca2+ mobilization, gamete formation, and gametes egress out of erythrocytes. GEP1 interacts with GCα, a cGMP synthesizing enzyme in gametocytes. Both GEP1 and GCα are expressed in cytoplasmic puncta of both male and female gametocytes. Depletion of GCα impairs XA-stimulated gametogenesis, mimicking the defect of GEP1 disruption. The identification of GEP1 being essential for gametogenesis provides a potential new target for intervention of parasite transmission.

Midline Volume Filler Injection for Facial Rejuvenation and Contouring in Asians.

BACKGROUND: Hyaluronic acid (HA) injection is popular in cosmetic surgery because of its minimal invasion and immediate recovery. However, few injection techniques are specifically designed for Asians, considering their aesthetic and structural differences from those of Caucasians. METHODS: The midline volume injection technique was performed on 37 Asian females and 3 males at sites including the forehead, glabella, nasal dorsum, nasal base and chin. The treatment focused on improving the facial profile projection. 3D image data were collected, and facial aesthetic angles were calculated. Volume changes in facial parts were analyzed before injection and during follow-up. Patient satisfaction was assessed using the visual analog scale (VAS). RESULTS: The average injected filler volume was 6.14 ± 2.82 ml. The treatment optimized the facial contour and produced instant facial rejuvenation. On 3D images, the average midline volume increased by 6.02 ± 2.23 ml. An average volume decrease of 3.92 ± 1.94 ml was observed in the cheeks and was positively related to the increased midline volume. The average nasolabial and nasal facial angles were increased from 100.00 ± 7.37° to 107.93 ± 9.01° and 28.78 ± 3.28° to 31.78 ± 2.97°, while the mentolabial angle was decreased from 146.55 ± 7.83° to 141.13 ± 6.23°. The mean VAS scores were 2.28 ± 1.27 immediately after injection and 2.56 ± 1.20 after 6 months. CONCLUSIONS: The midline volume injection technique of HA fillers is suitable for Asians. It greatly enhances the facial profile, as illustrated by volume changes in 3D images, leading to a more attractive facial appearance. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Isotherm ranking and selection using thirteen literature datasets involving hydrophobic organic compounds.

Numerous isotherm expressions have been developed for describing sorption of hydrophobic organic compounds (HOCs), including "dual-mode" approaches that combine nonlinear behavior with a linear partitioning component. Choosing among these alternative expressions for describing a given dataset is an important task that can significantly influence subsequent transport modeling and/or mechanistic interpretation. In this study, a series of numerical experiments were undertaken to identify "best-in-class" isotherms by refitting 10 alternative models to a suite of 13 previously published literature datasets. The corrected Akaike Information Criterion (AICc) was used for ranking these alternative fits and distinguishing between plausible and implausible isotherms for each dataset. The occurrence of multiple plausible isotherms was inversely correlated with dataset "richness", such that datasets with fewer observations and/or a narrow range of aqueous concentrations resulted in a greater number of plausible isotherms. Overall, only the Polanyi-partition dual-mode isotherm was classified as "plausible" across all 13 of the considered datasets, indicating substantial statistical support consistent with current advances in sorption theory. However, these findings are predicated on the use of the AICc measure as an unbiased ranking metric and the adoption of a subjective, but defensible, threshold for separating plausible and implausible isotherms.