BackgroundYarrowia lipolytica, a non-traditional oil yeast, has been widely used as a platform for lipid production. However, the production of other chemicals such as terpenoids in engineered Y. lipolytica is still low. α-Farnesene, a sesquiterpene, can be used in medicine, bioenergy and other fields, and has very high economic value. Here, we used α-farnesene as an example to explore the potential of Y. lipolytica for terpenoid production.ResultsWe constructed libraries of strains overexpressing mevalonate pathway and α-farnesene synthase genes by non-homologous end-joining (NHEJ) mediated integration into the Y. lipolytica chromosome. First, a mevalonate overproduction strain was selected by overexpressing relevant genes and changing the cofactor specificity. Based on this strain, the downstream α-farnesene synthesis pathway was overexpressed by iterative integration. Culture conditions were also optimized. A strain that produced 25.55 g/L α-farnesene was obtained. This is the highest terpenoid titer reported in Y. lipolytica.ConclusionsYarrowia lipolytica is a potentially valuable species for terpenoid production, and NHEJ-mediated modular integration is effective for expression library construction and screening of high-producer strains.
Standard nasal devices are inadequate to deliver clinically significant olfactory dosages without excess drug losses in other nasal epitheliums. The Sar-Gel based colorimetry method appears to provide a simple and practical approach to visualize and quantify regional deposition.
A self-supported, binder-free and scalable nanoporous carbon scaffold serves as an excellent host for the efficient and uniform atomic layer deposition of Pt nanoparticles, showing exemplary performance as a cathode catalyst layer in a PEM fuel cell.
The bi directional technique with a vibrating mesh nebulizer is recommended for both nasal systematic and olfactory drug deliveries. The Sar-Gel based method in combination with sectional nasal casts appears to be a practical approach to visualize local depositions.
Recently, carboxylate metal‐organic framework (MOF) materials were reported to perform well as anode materials for lithium‐ion batteries (LIBs); however, the presumed lithium storage mechanism of MOFs is controversial. To gain insight into the mechanism of MOFs as anode materials for LIBs, a self‐supported Cu‐TCNQ (TCNQ: 7,7,8,8‐tetracyanoquinodimethane) film was fabricated via an in situ redox routine, and directly used as electrode for LIBs. The first discharge and charge specific capacities of the self‐supported Cu‐TCNQ electrode are 373.4 and 219.4 mAh g−1, respectively. After 500 cycles, the reversible specific capacity of Cu‐TCNQ reaches 280.9 mAh g−1 at a current density of 100 mA g−1. Mutually validated data reveal that the high capacity is ascribed to the multiple‐electron redox conversion of both metal ions and ligands, as well as the reversible insertion and desertion of Li+ ions into the benzene rings of ligands. This work raises the expectation for MOFs as electrode materials of LIBs by utilizing multiple active sites and provides new clues for designing improved electrode materials for LIBs.
Summary
With advanced sequencing technology, dozens of complex polyploid plant genomes have been characterized. However, for many polyploid species, their diploid ancestors are unknown or extinct, making it impossible to unravel the subgenomes and genome evolution directly.
We developed a novel subgenome‐phasing algorithm, SubPhaser, specifically designed for a neoallopolyploid or a homoploid hybrid. SubPhaser first searches for the subgenome‐specific sequence (k‐mer), then assigns homoeologous chromosomes into subgenomes, and further provides tools to annotate and investigate specific sequences.
SubPhaser works well on neoallopolyploids and homoploid hybrids containing subgenome‐specific sequences like wheat, but fails on autopolyploids lacking subgenome‐specific sequences like alfalfa, indicating that SubPhaser can phase neoallopolyploid/homoploid hybrids with high accuracy, sensitivity and performance.
This highly accurate, highly sensitive, ancestral data free chromosome phasing algorithm, SubPhaser, offers significant application value for subgenome phasing in neoallopolyploids and homoploid hybrids, and for the subsequent exploration of genome evolution and related genetic/epigenetic mechanisms.
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