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Mid-life stage adults are at higher risk of developing venous thrombosis (VT)/thromboembolism (VT/E). Aging is characterized by an overproduction of reactive oxygen species (ROS), which could evoke a series of physiological changes involved in thrombosis. Here, we focus on the critical role of ROS within the red blood cell (RBC) in initiating venous thrombosis during aging. Growing evidence has shifted our interest in the role of unjustifiably unvalued RBCs in blood coagulation. RBCs can be a major source of oxidative stress during aging, since RBC redox homeostasis is generally compromised due to the discrepancy between prooxidants and antioxidants. As a result, ROS accumulate within the RBC due to the constant endogenous hemoglobin (Hb) autoxidation and NADPH oxidase activation, and the uptake of extracellular ROS released by other cells in the circulation. The elevated RBC ROS level affects the RBC membrane structure and function, causing loss of membrane integrity, and decreased deformability. These changes impair RBC function in hemostasis and thrombosis, favoring a hypercoagulable state through enhanced RBC aggregation, RBC binding to endothelial cells affecting nitric oxide availability, RBC-induced platelet activation consequently modulating their activity, RBC interaction with and activation of coagulation factors, increased RBC phosphatidylserine exposure and release of microvesicles, accelerated aging and hemolysis. Thus, RBC oxidative stress during aging typifies an ultimate mechanism in system failure, which can affect major processes involved in the development of venous thrombosis in a variety of ways. The reevaluated concept of the critical role of RBC ROS in the activation of thrombotic events during aging will help identify potential targets for novel strategies to prevent/reduce the risk for VT/E or VT/E recurrences in mid-life stage adults.

Sickle cell disease (SCD) is an inherited monogenic disorder and the most common severe hemoglobinopathy in the world. SCD is characterized by a point mutation in the β-globin gene, which results in hemoglobin (Hb) S production, leading to a variety of mechanistic and phenotypic changes within the sickle red blood cell (RBC). In SCD, the sickle RBCs are the root cause of the disease and they are a primary source of oxidative stress since sickle RBC redox state is compromised due to an imbalance between prooxidants and antioxidants. This imbalance in redox state is a result of a continuous production of reactive oxygen species (ROS) within the sickle RBC caused by the constant endogenous Hb autoxidation and NADPH oxidase activation, as well as by a deficiency in the antioxidant defense system. Accumulation of non-neutralized ROS within the sickle RBCs affects RBC membrane structure and function, leading to membrane integrity deficiency, low deformability, phosphatidylserine exposure, and release of micro-vesicles. These oxidative stress-associated RBC phenotypic modifications consequently evoke a myriad of physiological changes involved in multi-system manifestations. Thus, RBC oxidative stress in SCD can ultimately instigate major processes involved in organ damage. The critical role of the sickle RBC ROS production and its regulation in SCD pathophysiology are discussed here.

Background Dopaxanthin is a natural pigment betaxanthins family member with the highest antioxidant and free radical scavenging activities. However, its relatively low content in plants limited the wide range of applications. Cost-efficient microbial production, therefore, showed an attractive alternative. Results Here, an Escherichia coli strain equipped with the de novo biosynthetic pathway for hyperproducing dopaxanthin was constructed by combining metabolic engineering and protein engineering. Firstly, a high-performance rate-limiting levodopa 4,5-dioxygenase (DODA) was mined and characterized based on sequence similarity searching followed by whole-cell catalysis and de novo synthesis strategy. Then, the catalytic efficiency of DODA was increased 34 times with directed evolution. The mutated DODA significantly facilitated the production of dopaxanthin, with an increase of 40.17% in plasmid expression and 64.11% in genome expression, respectively. Finally, through connecting the blocked pathway from 3-dehydroshikimate to levodopa ( l -DOPAOPA) and enhancing the expression level of DODA, a titer of dopaxanthin of 22.87 g/L was achieved from glucose as feedstock, which is 286 times higher than that in the previous report. Conclusion This work not only established a promising platform for the environmentally friendly production of dopaxanthin but also laid a foundation for the commercialization of other betalain.

Background Pyruvate is a widely used value-added chemical which also serves as a hub of various metabolic pathways. The fastest-growing bacterium Vibrio natriegens is a promising chassis for synthetic biology applications with high substrate uptake rates. The aim of this study was to investigate if the high substrate uptake rates of V. natriegens enable pyruvate production at high productivities. Results Two prophage gene clusters and several essential genes for the biosynthesis of byproducts were first deleted. In order to promote pyruvate accumulation, the key gene aceE encoding pyruvate dehydrogenase complex E1 component was down-regulated to reduce the carbon flux into the tricarboxylic acid cycle. Afterwards, the expression of ppc gene encoding phosphoenolpyruvate carboxylase was fine-tuned to balance the cell growth and pyruvate synthesis. The resulting strain PYR32 was able to produce 54.22 g/L pyruvate from glucose within 16 h, with a yield of 1.17 mol/mol and an average productivity of 3.39 g/L/h. In addition, this strain was also able to efficiently convert sucrose or gluconate into pyruvate at high titers. Conclusion A novel strain of V. natriegens was engineered which was capable to provide higher productivity in pyruvate synthesis. This study lays the foundation for the biosynthesis of pyruvate and its derivatives in fast-growing V. natriegens .

A homologous recombination (HR)-proficient Yarrowia lipolytica chassis was constructed without compromising multiple cellular robustness features, such as thermotolerance, cell viability, antioxidation, osmotolerance, and biosynthetic capacity.Modulating the multi invasion-induced rearrangement process, a DNA double-strand break repair pathway, is critical for multifragment single-site integration in Y. lipolytica.Introduction of original bacteriophage recombination proteins enabled Y. lipolytica multifragment multisite editing.The HR-proficient chassis exhibited high HR efficiency with short homologous arms and the ability to integrate ultra-long DNA fragments.The HR-proficient chassis demonstrated features of a trifunctional CRISPR system, including transcriptional activation, transcriptional repression, and gene editing. Homologous recombination (HR) greatly facilitates precise genome editing. However, most organisms prefer error-prone non-homologous end joining (NHEJ) for DNA double-strand break (DSB) repair. Here, the NHEJ-proficient Yarrowia lipolytica was transformed into a HR-proficient strain by systematic engineering of recombination machinery, regulating the multiinvasion-induced rearrangement (MIR) process, and expressing cognate single-stranded DNA-annealing protein (SSAP)–single-stranded DNA-binding protein (SSB) pairs. These strategies improved HR efficiency by 38.9, 1.6, and 1.2-fold compared with the NHEJ-deficient strain for multifragment multisite integration, and multi- and single-fragment single-site integration, respectively. Moreover, HR efficiency remained high at 58% even with 50-base pair (bp) homology arms (HAs) and reached 11% for simultaneously integrating two mega-DNA fragments (18.0 kb and 13.5 kb) at two genome sites. This strain also enabled simultaneous editing, repression, and activation of multiple genes, while cellular robustness parameters showed marked increases over the NHEJ-deficient strain. Our work provides a HR-proficient Y. lipolytica chassis allowing efficient and precise genome editing of this increasingly important microbe. [Display omitted] A robust homologous recombination (HR)-proficient Yarrowia lipolytica strain was constructed in this study. This chassis strain exhibited high HR efficiency in genome editing with varying numbers of fragments and genomic loci via different lengths of homology arms (HAs), and the capacity for simultaneous editing, repression, and activation without compromising cellular robustness. Furthermore, the substrate consumption and product biosynthesis of this chassis strain were superior to those of the nonhomologous end joining (NHEJ)-disrupted strain. This Y. lipolytica strain is a suitable chassis for fundamental and applied research, indicating a Technology Readiness Level (TRL) of 5/6. Given the conservation of DNA repair, the strategies adapted in this study can be applied to other NHEJ-proficient organisms, presenting a TRL of 2 for the corresponding strategies. Sharing of this chassis strain and corresponding strategies to the community for broader scenarios, such as gene deletion library construction, rapidly deployable cell factories, and genome-editing tool development, would enable full-scale implementation of this technology. Yarrowia lipolytica, an industrial yeast historically challenging for precision genome editing, was engineered to favor homologous recombination (HR) repair while retaining its native fitness. This capacity facilitates Y. lipolytica-based basic research and modern biotechnology. The strategies developed in this study provide a reference for the genetic engineering of other nonhomologous end joining(NHEJ)-preferring organisms.

Abstract l-Lysine is widely used as a nutrition supplement in feed, food, and beverage industries as well as a chemical intermediate. At present, great efforts are made to further decrease the cost of lysine to make it more competitive in the markets. Furthermore, lysine also shows potential as a feedstock to produce other high-value chemicals for active pharmaceutical ingredients, drugs, or materials. In this review, the current biomanufacturing of lysine is first presented. Second, the production of novel derivatives from lysine is discussed. Some chemicals like l-pipecolic acid, cadaverine, and 5-aminovalerate already have been obtained at a lab scale. Others like 6-aminocaproic acid, valerolactam, and caprolactam could be produced through a biological and chemical coupling pathway or be synthesized by a hypothetical pathway. This review demonstrates an active and expansive lysine industry, and these green biomanufacturing strategies could also be applied to enhance the competitiveness of other amino acid industry.

In order to alleviate the pressure on environmental resources faced by meat and dairy production and to satisfy the increasing demands of consumers for food safety and health, alternative proteins have drawn considerable attention in the food industry. However, despite the successive reports of alternative protein food, the processing and application foundation of alternative proteins for meat and dairy is still weak. This paper summarizes the nutritional composition and physicochemical characteristics of meat and dairy alternative proteins from four sources: plant proteins, fungal proteins, algal proteins and insect proteins. The difference between these alternative proteins to animal proteins, the effects of their structural features and environmental conditions on their properties, as well as the corresponding mechanism are compared and discussed. Though fungal proteins, algal proteins and insect proteins have shown some advantages over traditional plant proteins, such as the comparable protein content of insect proteins to meat, the better digestibility of fungal proteins and the better foaming properties of algal proteins, there is still a big gap between alternative proteins and meat and dairy proteins. In addition to needing to provide amino acid composition and digestibility similar to animal proteins, alternative proteins also face challenges such as maintaining good solubility and emulsion properties. Their nutritional and physicochemical properties still need thorough investigation, and for commercial application, it is important to develop and optimize industrial technology in alternative protein separation and modification.

Myocardial infarction (MI) imposes a huge medical and economic burden on society, and cardiac repair after MI involves a complex series of processes. Understanding the key mechanisms (such as apoptosis, autophagy, inflammation, and fibrosis) will facilitate further drug development and patient treatment. Presently, a substantial body of evidence suggests that the regulation of epigenetic processes contributes to cardiac repair following MI, with DNA methylation being among the notable epigenetic factors involved. This article will review the research on the mechanism of DNA methylation regulation after MI to provide some insights for future research and development of related drugs.

Yarrowia lipolytica has been widely used in the food biotech-related industry, where it plays the host’s role in producing erythritol. Nevertheless, a temperature of about 28°C–30°C has been estimated as the yeast’s optimal growth temperature, leading to the consumption of a considerable quantity of cooling water, especially in summer, which is obligatory for fermentation. Herein is described a method for improving the thermotolerance and erythritol production efficiency at high temperatures of Y. lipolytica . Through screening and testing different heat resistant devices, eight refactored engineered strains showed better growth at higher temperature and the antioxidant properties of the eight engineered strains were also improved. In addition, the erythritol titer, yield and productivity of the strain FOS11-Ctt1 represented the best among the eight strains, reaching at 39.25 g/L, 0.348 g/g glucose, and 0.55 g/L/h respectively, which were increased by 156%, 86% and 161% compared with the control strain, respectively. This study provides insight into an effective heat-resistant device that could enhance the thermotolerance and erythritol production of Y. lipolytica , which might be considered a valued scientific reference for other resistant strains’ construction.

Background Saccharomyces cerevisiae is widely used in traditional brewing and modern fermentation industries to produce biofuels, chemicals and other bioproducts, but challenged by various harsh industrial conditions, such as hyperosmotic, thermal and ethanol stresses. Thus, its stress tolerance enhancement has been attracting broad interests. Recently, CRISPR/Cas-based genome editing technology offers unprecedented tools to explore genetic modifications and performance improvement of S. cerevisiae. Results Here, we presented that the Target-AID (activation-induced cytidine deaminase) base editor of enabling C-to-T substitutions could be harnessed to generate in situ nucleotide changes on the S. cerevisiae genome, thereby introducing protein point mutations in cells. The general transcription factor gene SPT15 was targeted, and total 36 mutants with diversified stress tolerances were obtained. Among them, the 18 tolerant mutants against hyperosmotic, thermal and ethanol stresses showed more than 1.5-fold increases of fermentation capacities. These mutations were mainly enriched at the N-terminal region and the convex surface of the saddle-shaped structure of Spt15. Comparative transcriptome analysis of three most stress-tolerant (A140G, P169A and R238K) and two most stress-sensitive (S118L and L214V) mutants revealed common and distinctive impacted global transcription reprogramming and transcriptional regulatory hubs in response to stresses, and these five amino acid changes had different effects on the interactions of Spt15 with DNA and other proteins in the RNA Polymerase II transcription machinery according to protein structure alignment analysis. Conclusions Taken together, our results demonstrated that the Target-AID base editor provided a powerful tool for targeted in situ mutagenesis in S. cerevisiae and more potential targets of Spt15 residues for enhancing yeast stress tolerance.